Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 5621 insertions, 0 deletions

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
new file mode 100644
index 000000000..d594cd501
--- /dev/null
+++ b/net/ceph/osd_client.c
@@ -0,0 +1,5621 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#ifdef CONFIG_BLOCK
+#include <linux/bio.h>
+#endif
+
+#include <linux/ceph/ceph_features.h>
+#include <linux/ceph/libceph.h>
+#include <linux/ceph/osd_client.h>
+#include <linux/ceph/messenger.h>
+#include <linux/ceph/decode.h>
+#include <linux/ceph/auth.h>
+#include <linux/ceph/pagelist.h>
+#include <linux/ceph/striper.h>
+
+#define OSD_OPREPLY_FRONT_LEN	512
+
+static struct kmem_cache	*ceph_osd_request_cache;
+
+static const struct ceph_connection_operations osd_con_ops;
+
+/*
+ * Implement client access to distributed object storage cluster.
+ *
+ * All data objects are stored within a cluster/cloud of OSDs, or
+ * "object storage devices."  (Note that Ceph OSDs have _nothing_ to
+ * do with the T10 OSD extensions to SCSI.)  Ceph OSDs are simply
+ * remote daemons serving up and coordinating consistent and safe
+ * access to storage.
+ *
+ * Cluster membership and the mapping of data objects onto storage devices
+ * are described by the osd map.
+ *
+ * We keep track of pending OSD requests (read, write), resubmit
+ * requests to different OSDs when the cluster topology/data layout
+ * change, or retry the affected requests when the communications
+ * channel with an OSD is reset.
+ */
+
+static void link_request(struct ceph_osd *osd, struct ceph_osd_request *req);
+static void unlink_request(struct ceph_osd *osd, struct ceph_osd_request *req);
+static void link_linger(struct ceph_osd *osd,
+			struct ceph_osd_linger_request *lreq);
+static void unlink_linger(struct ceph_osd *osd,
+			  struct ceph_osd_linger_request *lreq);
+static void clear_backoffs(struct ceph_osd *osd);
+
+#if 1
+static inline bool rwsem_is_wrlocked(struct rw_semaphore *sem)
+{
+	bool wrlocked = true;
+
+	if (unlikely(down_read_trylock(sem))) {
+		wrlocked = false;
+		up_read(sem);
+	}
+
+	return wrlocked;
+}
+static inline void verify_osdc_locked(struct ceph_osd_client *osdc)
+{
+	WARN_ON(!rwsem_is_locked(&osdc->lock));
+}
+static inline void verify_osdc_wrlocked(struct ceph_osd_client *osdc)
+{
+	WARN_ON(!rwsem_is_wrlocked(&osdc->lock));
+}
+static inline void verify_osd_locked(struct ceph_osd *osd)
+{
+	struct ceph_osd_client *osdc = osd->o_osdc;
+
+	WARN_ON(!(mutex_is_locked(&osd->lock) &&
+		  rwsem_is_locked(&osdc->lock)) &&
+		!rwsem_is_wrlocked(&osdc->lock));
+}
+static inline void verify_lreq_locked(struct ceph_osd_linger_request *lreq)
+{
+	WARN_ON(!mutex_is_locked(&lreq->lock));
+}
+#else
+static inline void verify_osdc_locked(struct ceph_osd_client *osdc) { }
+static inline void verify_osdc_wrlocked(struct ceph_osd_client *osdc) { }
+static inline void verify_osd_locked(struct ceph_osd *osd) { }
+static inline void verify_lreq_locked(struct ceph_osd_linger_request *lreq) { }
+#endif
+
+/*
+ * calculate the mapping of a file extent onto an object, and fill out the
+ * request accordingly.  shorten extent as necessary if it crosses an
+ * object boundary.
+ *
+ * fill osd op in request message.
+ */
+static int calc_layout(struct ceph_file_layout *layout, u64 off, u64 *plen,
+			u64 *objnum, u64 *objoff, u64 *objlen)
+{
+	u64 orig_len = *plen;
+	u32 xlen;
+
+	/* object extent? */
+	ceph_calc_file_object_mapping(layout, off, orig_len, objnum,
+					  objoff, &xlen);
+	*objlen = xlen;
+	if (*objlen < orig_len) {
+		*plen = *objlen;
+		dout(" skipping last %llu, final file extent %llu~%llu\n",
+		     orig_len - *plen, off, *plen);
+	}
+
+	dout("calc_layout objnum=%llx %llu~%llu\n", *objnum, *objoff, *objlen);
+	return 0;
+}
+
+static void ceph_osd_data_init(struct ceph_osd_data *osd_data)
+{
+	memset(osd_data, 0, sizeof (*osd_data));
+	osd_data->type = CEPH_OSD_DATA_TYPE_NONE;
+}
+
+/*
+ * Consumes @pages if @own_pages is true.
+ */
+static void ceph_osd_data_pages_init(struct ceph_osd_data *osd_data,
+			struct page **pages, u64 length, u32 alignment,
+			bool pages_from_pool, bool own_pages)
+{
+	osd_data->type = CEPH_OSD_DATA_TYPE_PAGES;
+	osd_data->pages = pages;
+	osd_data->length = length;
+	osd_data->alignment = alignment;
+	osd_data->pages_from_pool = pages_from_pool;
+	osd_data->own_pages = own_pages;
+}
+
+/*
+ * Consumes a ref on @pagelist.
+ */
+static void ceph_osd_data_pagelist_init(struct ceph_osd_data *osd_data,
+			struct ceph_pagelist *pagelist)
+{
+	osd_data->type = CEPH_OSD_DATA_TYPE_PAGELIST;
+	osd_data->pagelist = pagelist;
+}
+
+#ifdef CONFIG_BLOCK
+static void ceph_osd_data_bio_init(struct ceph_osd_data *osd_data,
+				   struct ceph_bio_iter *bio_pos,
+				   u32 bio_length)
+{
+	osd_data->type = CEPH_OSD_DATA_TYPE_BIO;
+	osd_data->bio_pos = *bio_pos;
+	osd_data->bio_length = bio_length;
+}
+#endif /* CONFIG_BLOCK */
+
+static void ceph_osd_data_bvecs_init(struct ceph_osd_data *osd_data,
+				     struct ceph_bvec_iter *bvec_pos,
+				     u32 num_bvecs)
+{
+	osd_data->type = CEPH_OSD_DATA_TYPE_BVECS;
+	osd_data->bvec_pos = *bvec_pos;
+	osd_data->num_bvecs = num_bvecs;
+}
+
+static struct ceph_osd_data *
+osd_req_op_raw_data_in(struct ceph_osd_request *osd_req, unsigned int which)
+{
+	BUG_ON(which >= osd_req->r_num_ops);
+
+	return &osd_req->r_ops[which].raw_data_in;
+}
+
+struct ceph_osd_data *
+osd_req_op_extent_osd_data(struct ceph_osd_request *osd_req,
+			unsigned int which)
+{
+	return osd_req_op_data(osd_req, which, extent, osd_data);
+}
+EXPORT_SYMBOL(osd_req_op_extent_osd_data);
+
+void osd_req_op_raw_data_in_pages(struct ceph_osd_request *osd_req,
+			unsigned int which, struct page **pages,
+			u64 length, u32 alignment,
+			bool pages_from_pool, bool own_pages)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_raw_data_in(osd_req, which);
+	ceph_osd_data_pages_init(osd_data, pages, length, alignment,
+				pages_from_pool, own_pages);
+}
+EXPORT_SYMBOL(osd_req_op_raw_data_in_pages);
+
+void osd_req_op_extent_osd_data_pages(struct ceph_osd_request *osd_req,
+			unsigned int which, struct page **pages,
+			u64 length, u32 alignment,
+			bool pages_from_pool, bool own_pages)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
+	ceph_osd_data_pages_init(osd_data, pages, length, alignment,
+				pages_from_pool, own_pages);
+}
+EXPORT_SYMBOL(osd_req_op_extent_osd_data_pages);
+
+void osd_req_op_extent_osd_data_pagelist(struct ceph_osd_request *osd_req,
+			unsigned int which, struct ceph_pagelist *pagelist)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
+	ceph_osd_data_pagelist_init(osd_data, pagelist);
+}
+EXPORT_SYMBOL(osd_req_op_extent_osd_data_pagelist);
+
+#ifdef CONFIG_BLOCK
+void osd_req_op_extent_osd_data_bio(struct ceph_osd_request *osd_req,
+				    unsigned int which,
+				    struct ceph_bio_iter *bio_pos,
+				    u32 bio_length)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
+	ceph_osd_data_bio_init(osd_data, bio_pos, bio_length);
+}
+EXPORT_SYMBOL(osd_req_op_extent_osd_data_bio);
+#endif /* CONFIG_BLOCK */
+
+void osd_req_op_extent_osd_data_bvecs(struct ceph_osd_request *osd_req,
+				      unsigned int which,
+				      struct bio_vec *bvecs, u32 num_bvecs,
+				      u32 bytes)
+{
+	struct ceph_osd_data *osd_data;
+	struct ceph_bvec_iter it = {
+		.bvecs = bvecs,
+		.iter = { .bi_size = bytes },
+	};
+
+	osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
+	ceph_osd_data_bvecs_init(osd_data, &it, num_bvecs);
+}
+EXPORT_SYMBOL(osd_req_op_extent_osd_data_bvecs);
+
+void osd_req_op_extent_osd_data_bvec_pos(struct ceph_osd_request *osd_req,
+					 unsigned int which,
+					 struct ceph_bvec_iter *bvec_pos)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
+	ceph_osd_data_bvecs_init(osd_data, bvec_pos, 0);
+}
+EXPORT_SYMBOL(osd_req_op_extent_osd_data_bvec_pos);
+
+static void osd_req_op_cls_request_info_pagelist(
+			struct ceph_osd_request *osd_req,
+			unsigned int which, struct ceph_pagelist *pagelist)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_data(osd_req, which, cls, request_info);
+	ceph_osd_data_pagelist_init(osd_data, pagelist);
+}
+
+void osd_req_op_cls_request_data_pagelist(
+			struct ceph_osd_request *osd_req,
+			unsigned int which, struct ceph_pagelist *pagelist)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_data(osd_req, which, cls, request_data);
+	ceph_osd_data_pagelist_init(osd_data, pagelist);
+	osd_req->r_ops[which].cls.indata_len += pagelist->length;
+	osd_req->r_ops[which].indata_len += pagelist->length;
+}
+EXPORT_SYMBOL(osd_req_op_cls_request_data_pagelist);
+
+void osd_req_op_cls_request_data_pages(struct ceph_osd_request *osd_req,
+			unsigned int which, struct page **pages, u64 length,
+			u32 alignment, bool pages_from_pool, bool own_pages)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_data(osd_req, which, cls, request_data);
+	ceph_osd_data_pages_init(osd_data, pages, length, alignment,
+				pages_from_pool, own_pages);
+	osd_req->r_ops[which].cls.indata_len += length;
+	osd_req->r_ops[which].indata_len += length;
+}
+EXPORT_SYMBOL(osd_req_op_cls_request_data_pages);
+
+void osd_req_op_cls_request_data_bvecs(struct ceph_osd_request *osd_req,
+				       unsigned int which,
+				       struct bio_vec *bvecs, u32 num_bvecs,
+				       u32 bytes)
+{
+	struct ceph_osd_data *osd_data;
+	struct ceph_bvec_iter it = {
+		.bvecs = bvecs,
+		.iter = { .bi_size = bytes },
+	};
+
+	osd_data = osd_req_op_data(osd_req, which, cls, request_data);
+	ceph_osd_data_bvecs_init(osd_data, &it, num_bvecs);
+	osd_req->r_ops[which].cls.indata_len += bytes;
+	osd_req->r_ops[which].indata_len += bytes;
+}
+EXPORT_SYMBOL(osd_req_op_cls_request_data_bvecs);
+
+void osd_req_op_cls_response_data_pages(struct ceph_osd_request *osd_req,
+			unsigned int which, struct page **pages, u64 length,
+			u32 alignment, bool pages_from_pool, bool own_pages)
+{
+	struct ceph_osd_data *osd_data;
+
+	osd_data = osd_req_op_data(osd_req, which, cls, response_data);
+	ceph_osd_data_pages_init(osd_data, pages, length, alignment,
+				pages_from_pool, own_pages);
+}
+EXPORT_SYMBOL(osd_req_op_cls_response_data_pages);
+
+static u64 ceph_osd_data_length(struct ceph_osd_data *osd_data)
+{
+	switch (osd_data->type) {
+	case CEPH_OSD_DATA_TYPE_NONE:
+		return 0;
+	case CEPH_OSD_DATA_TYPE_PAGES:
+		return osd_data->length;
+	case CEPH_OSD_DATA_TYPE_PAGELIST:
+		return (u64)osd_data->pagelist->length;
+#ifdef CONFIG_BLOCK
+	case CEPH_OSD_DATA_TYPE_BIO:
+		return (u64)osd_data->bio_length;
+#endif /* CONFIG_BLOCK */
+	case CEPH_OSD_DATA_TYPE_BVECS:
+		return osd_data->bvec_pos.iter.bi_size;
+	default:
+		WARN(true, "unrecognized data type %d\n", (int)osd_data->type);
+		return 0;
+	}
+}
+
+static void ceph_osd_data_release(struct ceph_osd_data *osd_data)
+{
+	if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGES && osd_data->own_pages) {
+		int num_pages;
+
+		num_pages = calc_pages_for((u64)osd_data->alignment,
+						(u64)osd_data->length);
+		ceph_release_page_vector(osd_data->pages, num_pages);
+	} else if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGELIST) {
+		ceph_pagelist_release(osd_data->pagelist);
+	}
+	ceph_osd_data_init(osd_data);
+}
+
+static void osd_req_op_data_release(struct ceph_osd_request *osd_req,
+			unsigned int which)
+{
+	struct ceph_osd_req_op *op;
+
+	BUG_ON(which >= osd_req->r_num_ops);
+	op = &osd_req->r_ops[which];
+
+	switch (op->op) {
+	case CEPH_OSD_OP_READ:
+	case CEPH_OSD_OP_WRITE:
+	case CEPH_OSD_OP_WRITEFULL:
+		ceph_osd_data_release(&op->extent.osd_data);
+		break;
+	case CEPH_OSD_OP_CALL:
+		ceph_osd_data_release(&op->cls.request_info);
+		ceph_osd_data_release(&op->cls.request_data);
+		ceph_osd_data_release(&op->cls.response_data);
+		break;
+	case CEPH_OSD_OP_SETXATTR:
+	case CEPH_OSD_OP_CMPXATTR:
+		ceph_osd_data_release(&op->xattr.osd_data);
+		break;
+	case CEPH_OSD_OP_STAT:
+		ceph_osd_data_release(&op->raw_data_in);
+		break;
+	case CEPH_OSD_OP_NOTIFY_ACK:
+		ceph_osd_data_release(&op->notify_ack.request_data);
+		break;
+	case CEPH_OSD_OP_NOTIFY:
+		ceph_osd_data_release(&op->notify.request_data);
+		ceph_osd_data_release(&op->notify.response_data);
+		break;
+	case CEPH_OSD_OP_LIST_WATCHERS:
+		ceph_osd_data_release(&op->list_watchers.response_data);
+		break;
+	case CEPH_OSD_OP_COPY_FROM2:
+		ceph_osd_data_release(&op->copy_from.osd_data);
+		break;
+	default:
+		break;
+	}
+}
+
+/*
+ * Assumes @t is zero-initialized.
+ */
+static void target_init(struct ceph_osd_request_target *t)
+{
+	ceph_oid_init(&t->base_oid);
+	ceph_oloc_init(&t->base_oloc);
+	ceph_oid_init(&t->target_oid);
+	ceph_oloc_init(&t->target_oloc);
+
+	ceph_osds_init(&t->acting);
+	ceph_osds_init(&t->up);
+	t->size = -1;
+	t->min_size = -1;
+
+	t->osd = CEPH_HOMELESS_OSD;
+}
+
+static void target_copy(struct ceph_osd_request_target *dest,
+			const struct ceph_osd_request_target *src)
+{
+	ceph_oid_copy(&dest->base_oid, &src->base_oid);
+	ceph_oloc_copy(&dest->base_oloc, &src->base_oloc);
+	ceph_oid_copy(&dest->target_oid, &src->target_oid);
+	ceph_oloc_copy(&dest->target_oloc, &src->target_oloc);
+
+	dest->pgid = src->pgid; /* struct */
+	dest->spgid = src->spgid; /* struct */
+	dest->pg_num = src->pg_num;
+	dest->pg_num_mask = src->pg_num_mask;
+	ceph_osds_copy(&dest->acting, &src->acting);
+	ceph_osds_copy(&dest->up, &src->up);
+	dest->size = src->size;
+	dest->min_size = src->min_size;
+	dest->sort_bitwise = src->sort_bitwise;
+	dest->recovery_deletes = src->recovery_deletes;
+
+	dest->flags = src->flags;
+	dest->used_replica = src->used_replica;
+	dest->paused = src->paused;
+
+	dest->epoch = src->epoch;
+	dest->last_force_resend = src->last_force_resend;
+
+	dest->osd = src->osd;
+}
+
+static void target_destroy(struct ceph_osd_request_target *t)
+{
+	ceph_oid_destroy(&t->base_oid);
+	ceph_oloc_destroy(&t->base_oloc);
+	ceph_oid_destroy(&t->target_oid);
+	ceph_oloc_destroy(&t->target_oloc);
+}
+
+/*
+ * requests
+ */
+static void request_release_checks(struct ceph_osd_request *req)
+{
+	WARN_ON(!RB_EMPTY_NODE(&req->r_node));
+	WARN_ON(!RB_EMPTY_NODE(&req->r_mc_node));
+	WARN_ON(!list_empty(&req->r_private_item));
+	WARN_ON(req->r_osd);
+}
+
+static void ceph_osdc_release_request(struct kref *kref)
+{
+	struct ceph_osd_request *req = container_of(kref,
+					    struct ceph_osd_request, r_kref);
+	unsigned int which;
+
+	dout("%s %p (r_request %p r_reply %p)\n", __func__, req,
+	     req->r_request, req->r_reply);
+	request_release_checks(req);
+
+	if (req->r_request)
+		ceph_msg_put(req->r_request);
+	if (req->r_reply)
+		ceph_msg_put(req->r_reply);
+
+	for (which = 0; which < req->r_num_ops; which++)
+		osd_req_op_data_release(req, which);
+
+	target_destroy(&req->r_t);
+	ceph_put_snap_context(req->r_snapc);
+
+	if (req->r_mempool)
+		mempool_free(req, req->r_osdc->req_mempool);
+	else if (req->r_num_ops <= CEPH_OSD_SLAB_OPS)
+		kmem_cache_free(ceph_osd_request_cache, req);
+	else
+		kfree(req);
+}
+
+void ceph_osdc_get_request(struct ceph_osd_request *req)
+{
+	dout("%s %p (was %d)\n", __func__, req,
+	     kref_read(&req->r_kref));
+	kref_get(&req->r_kref);
+}
+EXPORT_SYMBOL(ceph_osdc_get_request);
+
+void ceph_osdc_put_request(struct ceph_osd_request *req)
+{
+	if (req) {
+		dout("%s %p (was %d)\n", __func__, req,
+		     kref_read(&req->r_kref));
+		kref_put(&req->r_kref, ceph_osdc_release_request);
+	}
+}
+EXPORT_SYMBOL(ceph_osdc_put_request);
+
+static void request_init(struct ceph_osd_request *req)
+{
+	/* req only, each op is zeroed in osd_req_op_init() */
+	memset(req, 0, sizeof(*req));
+
+	kref_init(&req->r_kref);
+	init_completion(&req->r_completion);
+	RB_CLEAR_NODE(&req->r_node);
+	RB_CLEAR_NODE(&req->r_mc_node);
+	INIT_LIST_HEAD(&req->r_private_item);
+
+	target_init(&req->r_t);
+}
+
+struct ceph_osd_request *ceph_osdc_alloc_request(struct ceph_osd_client *osdc,
+					       struct ceph_snap_context *snapc,
+					       unsigned int num_ops,
+					       bool use_mempool,
+					       gfp_t gfp_flags)
+{
+	struct ceph_osd_request *req;
+
+	if (use_mempool) {
+		BUG_ON(num_ops > CEPH_OSD_SLAB_OPS);
+		req = mempool_alloc(osdc->req_mempool, gfp_flags);
+	} else if (num_ops <= CEPH_OSD_SLAB_OPS) {
+		req = kmem_cache_alloc(ceph_osd_request_cache, gfp_flags);
+	} else {
+		BUG_ON(num_ops > CEPH_OSD_MAX_OPS);
+		req = kmalloc(struct_size(req, r_ops, num_ops), gfp_flags);
+	}
+	if (unlikely(!req))
+		return NULL;
+
+	request_init(req);
+	req->r_osdc = osdc;
+	req->r_mempool = use_mempool;
+	req->r_num_ops = num_ops;
+	req->r_snapid = CEPH_NOSNAP;
+	req->r_snapc = ceph_get_snap_context(snapc);
+
+	dout("%s req %p\n", __func__, req);
+	return req;
+}
+EXPORT_SYMBOL(ceph_osdc_alloc_request);
+
+static int ceph_oloc_encoding_size(const struct ceph_object_locator *oloc)
+{
+	return 8 + 4 + 4 + 4 + (oloc->pool_ns ? oloc->pool_ns->len : 0);
+}
+
+static int __ceph_osdc_alloc_messages(struct ceph_osd_request *req, gfp_t gfp,
+				      int num_request_data_items,
+				      int num_reply_data_items)
+{
+	struct ceph_osd_client *osdc = req->r_osdc;
+	struct ceph_msg *msg;
+	int msg_size;
+
+	WARN_ON(req->r_request || req->r_reply);
+	WARN_ON(ceph_oid_empty(&req->r_base_oid));
+	WARN_ON(ceph_oloc_empty(&req->r_base_oloc));
+
+	/* create request message */
+	msg_size = CEPH_ENCODING_START_BLK_LEN +
+			CEPH_PGID_ENCODING_LEN + 1; /* spgid */
+	msg_size += 4 + 4 + 4; /* hash, osdmap_epoch, flags */
+	msg_size += CEPH_ENCODING_START_BLK_LEN +
+			sizeof(struct ceph_osd_reqid); /* reqid */
+	msg_size += sizeof(struct ceph_blkin_trace_info); /* trace */
+	msg_size += 4 + sizeof(struct ceph_timespec); /* client_inc, mtime */
+	msg_size += CEPH_ENCODING_START_BLK_LEN +
+			ceph_oloc_encoding_size(&req->r_base_oloc); /* oloc */
+	msg_size += 4 + req->r_base_oid.name_len; /* oid */
+	msg_size += 2 + req->r_num_ops * sizeof(struct ceph_osd_op);
+	msg_size += 8; /* snapid */
+	msg_size += 8; /* snap_seq */
+	msg_size += 4 + 8 * (req->r_snapc ? req->r_snapc->num_snaps : 0);
+	msg_size += 4 + 8; /* retry_attempt, features */
+
+	if (req->r_mempool)
+		msg = ceph_msgpool_get(&osdc->msgpool_op, msg_size,
+				       num_request_data_items);
+	else
+		msg = ceph_msg_new2(CEPH_MSG_OSD_OP, msg_size,
+				    num_request_data_items, gfp, true);
+	if (!msg)
+		return -ENOMEM;
+
+	memset(msg->front.iov_base, 0, msg->front.iov_len);
+	req->r_request = msg;
+
+	/* create reply message */
+	msg_size = OSD_OPREPLY_FRONT_LEN;
+	msg_size += req->r_base_oid.name_len;
+	msg_size += req->r_num_ops * sizeof(struct ceph_osd_op);
+
+	if (req->r_mempool)
+		msg = ceph_msgpool_get(&osdc->msgpool_op_reply, msg_size,
+				       num_reply_data_items);
+	else
+		msg = ceph_msg_new2(CEPH_MSG_OSD_OPREPLY, msg_size,
+				    num_reply_data_items, gfp, true);
+	if (!msg)
+		return -ENOMEM;
+
+	req->r_reply = msg;
+
+	return 0;
+}
+
+static bool osd_req_opcode_valid(u16 opcode)
+{
+	switch (opcode) {
+#define GENERATE_CASE(op, opcode, str)	case CEPH_OSD_OP_##op: return true;
+__CEPH_FORALL_OSD_OPS(GENERATE_CASE)
+#undef GENERATE_CASE
+	default:
+		return false;
+	}
+}
+
+static void get_num_data_items(struct ceph_osd_request *req,
+			       int *num_request_data_items,
+			       int *num_reply_data_items)
+{
+	struct ceph_osd_req_op *op;
+
+	*num_request_data_items = 0;
+	*num_reply_data_items = 0;
+
+	for (op = req->r_ops; op != &req->r_ops[req->r_num_ops]; op++) {
+		switch (op->op) {
+		/* request */
+		case CEPH_OSD_OP_WRITE:
+		case CEPH_OSD_OP_WRITEFULL:
+		case CEPH_OSD_OP_SETXATTR:
+		case CEPH_OSD_OP_CMPXATTR:
+		case CEPH_OSD_OP_NOTIFY_ACK:
+		case CEPH_OSD_OP_COPY_FROM2:
+			*num_request_data_items += 1;
+			break;
+
+		/* reply */
+		case CEPH_OSD_OP_STAT:
+		case CEPH_OSD_OP_READ:
+		case CEPH_OSD_OP_LIST_WATCHERS:
+			*num_reply_data_items += 1;
+			break;
+
+		/* both */
+		case CEPH_OSD_OP_NOTIFY:
+			*num_request_data_items += 1;
+			*num_reply_data_items += 1;
+			break;
+		case CEPH_OSD_OP_CALL:
+			*num_request_data_items += 2;
+			*num_reply_data_items += 1;
+			break;
+
+		default:
+			WARN_ON(!osd_req_opcode_valid(op->op));
+			break;
+		}
+	}
+}
+
+/*
+ * oid, oloc and OSD op opcode(s) must be filled in before this function
+ * is called.
+ */
+int ceph_osdc_alloc_messages(struct ceph_osd_request *req, gfp_t gfp)
+{
+	int num_request_data_items, num_reply_data_items;
+
+	get_num_data_items(req, &num_request_data_items, &num_reply_data_items);
+	return __ceph_osdc_alloc_messages(req, gfp, num_request_data_items,
+					  num_reply_data_items);
+}
+EXPORT_SYMBOL(ceph_osdc_alloc_messages);
+
+/*
+ * This is an osd op init function for opcodes that have no data or
+ * other information associated with them.  It also serves as a
+ * common init routine for all the other init functions, below.
+ */
+struct ceph_osd_req_op *
+osd_req_op_init(struct ceph_osd_request *osd_req, unsigned int which,
+		 u16 opcode, u32 flags)
+{
+	struct ceph_osd_req_op *op;
+
+	BUG_ON(which >= osd_req->r_num_ops);
+	BUG_ON(!osd_req_opcode_valid(opcode));
+
+	op = &osd_req->r_ops[which];
+	memset(op, 0, sizeof (*op));
+	op->op = opcode;
+	op->flags = flags;
+
+	return op;
+}
+EXPORT_SYMBOL(osd_req_op_init);
+
+void osd_req_op_extent_init(struct ceph_osd_request *osd_req,
+				unsigned int which, u16 opcode,
+				u64 offset, u64 length,
+				u64 truncate_size, u32 truncate_seq)
+{
+	struct ceph_osd_req_op *op = osd_req_op_init(osd_req, which,
+						     opcode, 0);
+	size_t payload_len = 0;
+
+	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
+	       opcode != CEPH_OSD_OP_WRITEFULL && opcode != CEPH_OSD_OP_ZERO &&
+	       opcode != CEPH_OSD_OP_TRUNCATE);
+
+	op->extent.offset = offset;
+	op->extent.length = length;
+	op->extent.truncate_size = truncate_size;
+	op->extent.truncate_seq = truncate_seq;
+	if (opcode == CEPH_OSD_OP_WRITE || opcode == CEPH_OSD_OP_WRITEFULL)
+		payload_len += length;
+
+	op->indata_len = payload_len;
+}
+EXPORT_SYMBOL(osd_req_op_extent_init);
+
+void osd_req_op_extent_update(struct ceph_osd_request *osd_req,
+				unsigned int which, u64 length)
+{
+	struct ceph_osd_req_op *op;
+	u64 previous;
+
+	BUG_ON(which >= osd_req->r_num_ops);
+	op = &osd_req->r_ops[which];
+	previous = op->extent.length;
+
+	if (length == previous)
+		return;		/* Nothing to do */
+	BUG_ON(length > previous);
+
+	op->extent.length = length;
+	if (op->op == CEPH_OSD_OP_WRITE || op->op == CEPH_OSD_OP_WRITEFULL)
+		op->indata_len -= previous - length;
+}
+EXPORT_SYMBOL(osd_req_op_extent_update);
+
+void osd_req_op_extent_dup_last(struct ceph_osd_request *osd_req,
+				unsigned int which, u64 offset_inc)
+{
+	struct ceph_osd_req_op *op, *prev_op;
+
+	BUG_ON(which + 1 >= osd_req->r_num_ops);
+
+	prev_op = &osd_req->r_ops[which];
+	op = osd_req_op_init(osd_req, which + 1, prev_op->op, prev_op->flags);
+	/* dup previous one */
+	op->indata_len = prev_op->indata_len;
+	op->outdata_len = prev_op->outdata_len;
+	op->extent = prev_op->extent;
+	/* adjust offset */
+	op->extent.offset += offset_inc;
+	op->extent.length -= offset_inc;
+
+	if (op->op == CEPH_OSD_OP_WRITE || op->op == CEPH_OSD_OP_WRITEFULL)
+		op->indata_len -= offset_inc;
+}
+EXPORT_SYMBOL(osd_req_op_extent_dup_last);
+
+int osd_req_op_cls_init(struct ceph_osd_request *osd_req, unsigned int which,
+			const char *class, const char *method)
+{
+	struct ceph_osd_req_op *op;
+	struct ceph_pagelist *pagelist;
+	size_t payload_len = 0;
+	size_t size;
+	int ret;
+
+	op = osd_req_op_init(osd_req, which, CEPH_OSD_OP_CALL, 0);
+
+	pagelist = ceph_pagelist_alloc(GFP_NOFS);
+	if (!pagelist)
+		return -ENOMEM;
+
+	op->cls.class_name = class;
+	size = strlen(class);
+	BUG_ON(size > (size_t) U8_MAX);
+	op->cls.class_len = size;
+	ret = ceph_pagelist_append(pagelist, class, size);
+	if (ret)
+		goto err_pagelist_free;
+	payload_len += size;
+
+	op->cls.method_name = method;
+	size = strlen(method);
+	BUG_ON(size > (size_t) U8_MAX);
+	op->cls.method_len = size;
+	ret = ceph_pagelist_append(pagelist, method, size);
+	if (ret)
+		goto err_pagelist_free;
+	payload_len += size;
+
+	osd_req_op_cls_request_info_pagelist(osd_req, which, pagelist);
+	op->indata_len = payload_len;
+	return 0;
+
+err_pagelist_free:
+	ceph_pagelist_release(pagelist);
+	return ret;
+}
+EXPORT_SYMBOL(osd_req_op_cls_init);
+
+int osd_req_op_xattr_init(struct ceph_osd_request *osd_req, unsigned int which,
+			  u16 opcode, const char *name, const void *value,
+			  size_t size, u8 cmp_op, u8 cmp_mode)
+{
+	struct ceph_osd_req_op *op = osd_req_op_init(osd_req, which,
+						     opcode, 0);
+	struct ceph_pagelist *pagelist;
+	size_t payload_len;
+	int ret;
+
+	BUG_ON(opcode != CEPH_OSD_OP_SETXATTR && opcode != CEPH_OSD_OP_CMPXATTR);
+
+	pagelist = ceph_pagelist_alloc(GFP_NOFS);
+	if (!pagelist)
+		return -ENOMEM;
+
+	payload_len = strlen(name);
+	op->xattr.name_len = payload_len;
+	ret = ceph_pagelist_append(pagelist, name, payload_len);
+	if (ret)
+		goto err_pagelist_free;
+
+	op->xattr.value_len = size;
+	ret = ceph_pagelist_append(pagelist, value, size);
+	if (ret)
+		goto err_pagelist_free;
+	payload_len += size;
+
+	op->xattr.cmp_op = cmp_op;
+	op->xattr.cmp_mode = cmp_mode;
+
+	ceph_osd_data_pagelist_init(&op->xattr.osd_data, pagelist);
+	op->indata_len = payload_len;
+	return 0;
+
+err_pagelist_free:
+	ceph_pagelist_release(pagelist);
+	return ret;
+}
+EXPORT_SYMBOL(osd_req_op_xattr_init);
+
+/*
+ * @watch_opcode: CEPH_OSD_WATCH_OP_*
+ */
+static void osd_req_op_watch_init(struct ceph_osd_request *req, int which,
+				  u8 watch_opcode, u64 cookie, u32 gen)
+{
+	struct ceph_osd_req_op *op;
+
+	op = osd_req_op_init(req, which, CEPH_OSD_OP_WATCH, 0);
+	op->watch.cookie = cookie;
+	op->watch.op = watch_opcode;
+	op->watch.gen = gen;
+}
+
+/*
+ * prot_ver, timeout and notify payload (may be empty) should already be
+ * encoded in @request_pl
+ */
+static void osd_req_op_notify_init(struct ceph_osd_request *req, int which,
+				   u64 cookie, struct ceph_pagelist *request_pl)
+{
+	struct ceph_osd_req_op *op;
+
+	op = osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY, 0);
+	op->notify.cookie = cookie;
+
+	ceph_osd_data_pagelist_init(&op->notify.request_data, request_pl);
+	op->indata_len = request_pl->length;
+}
+
+/*
+ * @flags: CEPH_OSD_OP_ALLOC_HINT_FLAG_*
+ */
+void osd_req_op_alloc_hint_init(struct ceph_osd_request *osd_req,
+				unsigned int which,
+				u64 expected_object_size,
+				u64 expected_write_size,
+				u32 flags)
+{
+	struct ceph_osd_req_op *op;
+
+	op = osd_req_op_init(osd_req, which, CEPH_OSD_OP_SETALLOCHINT, 0);
+	op->alloc_hint.expected_object_size = expected_object_size;
+	op->alloc_hint.expected_write_size = expected_write_size;
+	op->alloc_hint.flags = flags;
+
+	/*
+	 * CEPH_OSD_OP_SETALLOCHINT op is advisory and therefore deemed
+	 * not worth a feature bit.  Set FAILOK per-op flag to make
+	 * sure older osds don't trip over an unsupported opcode.
+	 */
+	op->flags |= CEPH_OSD_OP_FLAG_FAILOK;
+}
+EXPORT_SYMBOL(osd_req_op_alloc_hint_init);
+
+static void ceph_osdc_msg_data_add(struct ceph_msg *msg,
+				struct ceph_osd_data *osd_data)
+{
+	u64 length = ceph_osd_data_length(osd_data);
+
+	if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGES) {
+		BUG_ON(length > (u64) SIZE_MAX);
+		if (length)
+			ceph_msg_data_add_pages(msg, osd_data->pages,
+					length, osd_data->alignment, false);
+	} else if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGELIST) {
+		BUG_ON(!length);
+		ceph_msg_data_add_pagelist(msg, osd_data->pagelist);
+#ifdef CONFIG_BLOCK
+	} else if (osd_data->type == CEPH_OSD_DATA_TYPE_BIO) {
+		ceph_msg_data_add_bio(msg, &osd_data->bio_pos, length);
+#endif
+	} else if (osd_data->type == CEPH_OSD_DATA_TYPE_BVECS) {
+		ceph_msg_data_add_bvecs(msg, &osd_data->bvec_pos);
+	} else {
+		BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_NONE);
+	}
+}
+
+static u32 osd_req_encode_op(struct ceph_osd_op *dst,
+			     const struct ceph_osd_req_op *src)
+{
+	switch (src->op) {
+	case CEPH_OSD_OP_STAT:
+		break;
+	case CEPH_OSD_OP_READ:
+	case CEPH_OSD_OP_WRITE:
+	case CEPH_OSD_OP_WRITEFULL:
+	case CEPH_OSD_OP_ZERO:
+	case CEPH_OSD_OP_TRUNCATE:
+		dst->extent.offset = cpu_to_le64(src->extent.offset);
+		dst->extent.length = cpu_to_le64(src->extent.length);
+		dst->extent.truncate_size =
+			cpu_to_le64(src->extent.truncate_size);
+		dst->extent.truncate_seq =
+			cpu_to_le32(src->extent.truncate_seq);
+		break;
+	case CEPH_OSD_OP_CALL:
+		dst->cls.class_len = src->cls.class_len;
+		dst->cls.method_len = src->cls.method_len;
+		dst->cls.indata_len = cpu_to_le32(src->cls.indata_len);
+		break;
+	case CEPH_OSD_OP_WATCH:
+		dst->watch.cookie = cpu_to_le64(src->watch.cookie);
+		dst->watch.ver = cpu_to_le64(0);
+		dst->watch.op = src->watch.op;
+		dst->watch.gen = cpu_to_le32(src->watch.gen);
+		break;
+	case CEPH_OSD_OP_NOTIFY_ACK:
+		break;
+	case CEPH_OSD_OP_NOTIFY:
+		dst->notify.cookie = cpu_to_le64(src->notify.cookie);
+		break;
+	case CEPH_OSD_OP_LIST_WATCHERS:
+		break;
+	case CEPH_OSD_OP_SETALLOCHINT:
+		dst->alloc_hint.expected_object_size =
+		    cpu_to_le64(src->alloc_hint.expected_object_size);
+		dst->alloc_hint.expected_write_size =
+		    cpu_to_le64(src->alloc_hint.expected_write_size);
+		dst->alloc_hint.flags = cpu_to_le32(src->alloc_hint.flags);
+		break;
+	case CEPH_OSD_OP_SETXATTR:
+	case CEPH_OSD_OP_CMPXATTR:
+		dst->xattr.name_len = cpu_to_le32(src->xattr.name_len);
+		dst->xattr.value_len = cpu_to_le32(src->xattr.value_len);
+		dst->xattr.cmp_op = src->xattr.cmp_op;
+		dst->xattr.cmp_mode = src->xattr.cmp_mode;
+		break;
+	case CEPH_OSD_OP_CREATE:
+	case CEPH_OSD_OP_DELETE:
+		break;
+	case CEPH_OSD_OP_COPY_FROM2:
+		dst->copy_from.snapid = cpu_to_le64(src->copy_from.snapid);
+		dst->copy_from.src_version =
+			cpu_to_le64(src->copy_from.src_version);
+		dst->copy_from.flags = src->copy_from.flags;
+		dst->copy_from.src_fadvise_flags =
+			cpu_to_le32(src->copy_from.src_fadvise_flags);
+		break;
+	default:
+		pr_err("unsupported osd opcode %s\n",
+			ceph_osd_op_name(src->op));
+		WARN_ON(1);
+
+		return 0;
+	}
+
+	dst->op = cpu_to_le16(src->op);
+	dst->flags = cpu_to_le32(src->flags);
+	dst->payload_len = cpu_to_le32(src->indata_len);
+
+	return src->indata_len;
+}
+
+/*
+ * build new request AND message, calculate layout, and adjust file
+ * extent as needed.
+ *
+ * if the file was recently truncated, we include information about its
+ * old and new size so that the object can be updated appropriately.  (we
+ * avoid synchronously deleting truncated objects because it's slow.)
+ */
+struct ceph_osd_request *ceph_osdc_new_request(struct ceph_osd_client *osdc,
+					       struct ceph_file_layout *layout,
+					       struct ceph_vino vino,
+					       u64 off, u64 *plen,
+					       unsigned int which, int num_ops,
+					       int opcode, int flags,
+					       struct ceph_snap_context *snapc,
+					       u32 truncate_seq,
+					       u64 truncate_size,
+					       bool use_mempool)
+{
+	struct ceph_osd_request *req;
+	u64 objnum = 0;
+	u64 objoff = 0;
+	u64 objlen = 0;
+	int r;
+
+	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
+	       opcode != CEPH_OSD_OP_ZERO && opcode != CEPH_OSD_OP_TRUNCATE &&
+	       opcode != CEPH_OSD_OP_CREATE && opcode != CEPH_OSD_OP_DELETE);
+
+	req = ceph_osdc_alloc_request(osdc, snapc, num_ops, use_mempool,
+					GFP_NOFS);
+	if (!req) {
+		r = -ENOMEM;
+		goto fail;
+	}
+
+	/* calculate max write size */
+	r = calc_layout(layout, off, plen, &objnum, &objoff, &objlen);
+	if (r)
+		goto fail;
+
+	if (opcode == CEPH_OSD_OP_CREATE || opcode == CEPH_OSD_OP_DELETE) {
+		osd_req_op_init(req, which, opcode, 0);
+	} else {
+		u32 object_size = layout->object_size;
+		u32 object_base = off - objoff;
+		if (!(truncate_seq == 1 && truncate_size == -1ULL)) {
+			if (truncate_size <= object_base) {
+				truncate_size = 0;
+			} else {
+				truncate_size -= object_base;
+				if (truncate_size > object_size)
+					truncate_size = object_size;
+			}
+		}
+		osd_req_op_extent_init(req, which, opcode, objoff, objlen,
+				       truncate_size, truncate_seq);
+	}
+
+	req->r_base_oloc.pool = layout->pool_id;
+	req->r_base_oloc.pool_ns = ceph_try_get_string(layout->pool_ns);
+	ceph_oid_printf(&req->r_base_oid, "%llx.%08llx", vino.ino, objnum);
+	req->r_flags = flags | osdc->client->options->read_from_replica;
+
+	req->r_snapid = vino.snap;
+	if (flags & CEPH_OSD_FLAG_WRITE)
+		req->r_data_offset = off;
+
+	if (num_ops > 1)
+		/*
+		 * This is a special case for ceph_writepages_start(), but it
+		 * also covers ceph_uninline_data().  If more multi-op request
+		 * use cases emerge, we will need a separate helper.
+		 */
+		r = __ceph_osdc_alloc_messages(req, GFP_NOFS, num_ops, 0);
+	else
+		r = ceph_osdc_alloc_messages(req, GFP_NOFS);
+	if (r)
+		goto fail;
+
+	return req;
+
+fail:
+	ceph_osdc_put_request(req);
+	return ERR_PTR(r);
+}
+EXPORT_SYMBOL(ceph_osdc_new_request);
+
+/*
+ * We keep osd requests in an rbtree, sorted by ->r_tid.
+ */
+DEFINE_RB_FUNCS(request, struct ceph_osd_request, r_tid, r_node)
+DEFINE_RB_FUNCS(request_mc, struct ceph_osd_request, r_tid, r_mc_node)
+
+/*
+ * Call @fn on each OSD request as long as @fn returns 0.
+ */
+static void for_each_request(struct ceph_osd_client *osdc,
+			int (*fn)(struct ceph_osd_request *req, void *arg),
+			void *arg)
+{
+	struct rb_node *n, *p;
+
+	for (n = rb_first(&osdc->osds); n; n = rb_next(n)) {
+		struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node);
+
+		for (p = rb_first(&osd->o_requests); p; ) {
+			struct ceph_osd_request *req =
+			    rb_entry(p, struct ceph_osd_request, r_node);
+
+			p = rb_next(p);
+			if (fn(req, arg))
+				return;
+		}
+	}
+
+	for (p = rb_first(&osdc->homeless_osd.o_requests); p; ) {
+		struct ceph_osd_request *req =
+		    rb_entry(p, struct ceph_osd_request, r_node);
+
+		p = rb_next(p);
+		if (fn(req, arg))
+			return;
+	}
+}
+
+static bool osd_homeless(struct ceph_osd *osd)
+{
+	return osd->o_osd == CEPH_HOMELESS_OSD;
+}
+
+static bool osd_registered(struct ceph_osd *osd)
+{
+	verify_osdc_locked(osd->o_osdc);
+
+	return !RB_EMPTY_NODE(&osd->o_node);
+}
+
+/*
+ * Assumes @osd is zero-initialized.
+ */
+static void osd_init(struct ceph_osd *osd)
+{
+	refcount_set(&osd->o_ref, 1);
+	RB_CLEAR_NODE(&osd->o_node);
+	osd->o_requests = RB_ROOT;
+	osd->o_linger_requests = RB_ROOT;
+	osd->o_backoff_mappings = RB_ROOT;
+	osd->o_backoffs_by_id = RB_ROOT;
+	INIT_LIST_HEAD(&osd->o_osd_lru);
+	INIT_LIST_HEAD(&osd->o_keepalive_item);
+	osd->o_incarnation = 1;
+	mutex_init(&osd->lock);
+}
+
+static void osd_cleanup(struct ceph_osd *osd)
+{
+	WARN_ON(!RB_EMPTY_NODE(&osd->o_node));
+	WARN_ON(!RB_EMPTY_ROOT(&osd->o_requests));
+	WARN_ON(!RB_EMPTY_ROOT(&osd->o_linger_requests));
+	WARN_ON(!RB_EMPTY_ROOT(&osd->o_backoff_mappings));
+	WARN_ON(!RB_EMPTY_ROOT(&osd->o_backoffs_by_id));
+	WARN_ON(!list_empty(&osd->o_osd_lru));
+	WARN_ON(!list_empty(&osd->o_keepalive_item));
+
+	if (osd->o_auth.authorizer) {
+		WARN_ON(osd_homeless(osd));
+		ceph_auth_destroy_authorizer(osd->o_auth.authorizer);
+	}
+}
+
+/*
+ * Track open sessions with osds.
+ */
+static struct ceph_osd *create_osd(struct ceph_osd_client *osdc, int onum)
+{
+	struct ceph_osd *osd;
+
+	WARN_ON(onum == CEPH_HOMELESS_OSD);
+
+	osd = kzalloc(sizeof(*osd), GFP_NOIO | __GFP_NOFAIL);
+	osd_init(osd);
+	osd->o_osdc = osdc;
+	osd->o_osd = onum;
+
+	ceph_con_init(&osd->o_con, osd, &osd_con_ops, &osdc->client->msgr);
+
+	return osd;
+}
+
+static struct ceph_osd *get_osd(struct ceph_osd *osd)
+{
+	if (refcount_inc_not_zero(&osd->o_ref)) {
+		dout("get_osd %p %d -> %d\n", osd, refcount_read(&osd->o_ref)-1,
+		     refcount_read(&osd->o_ref));
+		return osd;
+	} else {
+		dout("get_osd %p FAIL\n", osd);
+		return NULL;
+	}
+}
+
+static void put_osd(struct ceph_osd *osd)
+{
+	dout("put_osd %p %d -> %d\n", osd, refcount_read(&osd->o_ref),
+	     refcount_read(&osd->o_ref) - 1);
+	if (refcount_dec_and_test(&osd->o_ref)) {
+		osd_cleanup(osd);
+		kfree(osd);
+	}
+}
+
+DEFINE_RB_FUNCS(osd, struct ceph_osd, o_osd, o_node)
+
+static void __move_osd_to_lru(struct ceph_osd *osd)
+{
+	struct ceph_osd_client *osdc = osd->o_osdc;
+
+	dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);
+	BUG_ON(!list_empty(&osd->o_osd_lru));
+
+	spin_lock(&osdc->osd_lru_lock);
+	list_add_tail(&osd->o_osd_lru, &osdc->osd_lru);
+	spin_unlock(&osdc->osd_lru_lock);
+
+	osd->lru_ttl = jiffies + osdc->client->options->osd_idle_ttl;
+}
+
+static void maybe_move_osd_to_lru(struct ceph_osd *osd)
+{
+	if (RB_EMPTY_ROOT(&osd->o_requests) &&
+	    RB_EMPTY_ROOT(&osd->o_linger_requests))
+		__move_osd_to_lru(osd);
+}
+
+static void __remove_osd_from_lru(struct ceph_osd *osd)
+{
+	struct ceph_osd_client *osdc = osd->o_osdc;
+
+	dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);
+
+	spin_lock(&osdc->osd_lru_lock);
+	if (!list_empty(&osd->o_osd_lru))
+		list_del_init(&osd->o_osd_lru);
+	spin_unlock(&osdc->osd_lru_lock);
+}
+
+/*
+ * Close the connection and assign any leftover requests to the
+ * homeless session.
+ */
+static void close_osd(struct ceph_osd *osd)
+{
+	struct ceph_osd_client *osdc = osd->o_osdc;
+	struct rb_node *n;
+
+	verify_osdc_wrlocked(osdc);
+	dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);
+
+	ceph_con_close(&osd->o_con);
+
+	for (n = rb_first(&osd->o_requests); n; ) {
+		struct ceph_osd_request *req =
+		    rb_entry(n, struct ceph_osd_request, r_node);
+
+		n = rb_next(n); /* unlink_request() */
+
+		dout(" reassigning req %p tid %llu\n", req, req->r_tid);
+		unlink_request(osd, req);
+		link_request(&osdc->homeless_osd, req);
+	}
+	for (n = rb_first(&osd->o_linger_requests); n; ) {
+		struct ceph_osd_linger_request *lreq =
+		    rb_entry(n, struct ceph_osd_linger_request, node);
+
+		n = rb_next(n); /* unlink_linger() */
+
+		dout(" reassigning lreq %p linger_id %llu\n", lreq,
+		     lreq->linger_id);
+		unlink_linger(osd, lreq);
+		link_linger(&osdc->homeless_osd, lreq);
+	}
+	clear_backoffs(osd);
+
+	__remove_osd_from_lru(osd);
+	erase_osd(&osdc->osds, osd);
+	put_osd(osd);
+}
+
+/*
+ * reset osd connect
+ */
+static int reopen_osd(struct ceph_osd *osd)
+{
+	struct ceph_entity_addr *peer_addr;
+
+	dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);
+
+	if (RB_EMPTY_ROOT(&osd->o_requests) &&
+	    RB_EMPTY_ROOT(&osd->o_linger_requests)) {
+		close_osd(osd);
+		return -ENODEV;
+	}
+
+	peer_addr = &osd->o_osdc->osdmap->osd_addr[osd->o_osd];
+	if (!memcmp(peer_addr, &osd->o_con.peer_addr, sizeof (*peer_addr)) &&
+			!ceph_con_opened(&osd->o_con)) {
+		struct rb_node *n;
+
+		dout("osd addr hasn't changed and connection never opened, "
+		     "letting msgr retry\n");
+		/* touch each r_stamp for handle_timeout()'s benfit */
+		for (n = rb_first(&osd->o_requests); n; n = rb_next(n)) {
+			struct ceph_osd_request *req =
+			    rb_entry(n, struct ceph_osd_request, r_node);
+			req->r_stamp = jiffies;
+		}
+
+		return -EAGAIN;
+	}
+
+	ceph_con_close(&osd->o_con);
+	ceph_con_open(&osd->o_con, CEPH_ENTITY_TYPE_OSD, osd->o_osd, peer_addr);
+	osd->o_incarnation++;
+
+	return 0;
+}
+
+static struct ceph_osd *lookup_create_osd(struct ceph_osd_client *osdc, int o,
+					  bool wrlocked)
+{
+	struct ceph_osd *osd;
+
+	if (wrlocked)
+		verify_osdc_wrlocked(osdc);
+	else
+		verify_osdc_locked(osdc);
+
+	if (o != CEPH_HOMELESS_OSD)
+		osd = lookup_osd(&osdc->osds, o);
+	else
+		osd = &osdc->homeless_osd;
+	if (!osd) {
+		if (!wrlocked)
+			return ERR_PTR(-EAGAIN);
+
+		osd = create_osd(osdc, o);
+		insert_osd(&osdc->osds, osd);
+		ceph_con_open(&osd->o_con, CEPH_ENTITY_TYPE_OSD, osd->o_osd,
+			      &osdc->osdmap->osd_addr[osd->o_osd]);
+	}
+
+	dout("%s osdc %p osd%d -> osd %p\n", __func__, osdc, o, osd);
+	return osd;
+}
+
+/*
+ * Create request <-> OSD session relation.
+ *
+ * @req has to be assigned a tid, @osd may be homeless.
+ */
+static void link_request(struct ceph_osd *osd, struct ceph_osd_request *req)
+{
+	verify_osd_locked(osd);
+	WARN_ON(!req->r_tid || req->r_osd);
+	dout("%s osd %p osd%d req %p tid %llu\n", __func__, osd, osd->o_osd,
+	     req, req->r_tid);
+
+	if (!osd_homeless(osd))
+		__remove_osd_from_lru(osd);
+	else
+		atomic_inc(&osd->o_osdc->num_homeless);
+
+	get_osd(osd);
+	insert_request(&osd->o_requests, req);
+	req->r_osd = osd;
+}
+
+static void unlink_request(struct ceph_osd *osd, struct ceph_osd_request *req)
+{
+	verify_osd_locked(osd);
+	WARN_ON(req->r_osd != osd);
+	dout("%s osd %p osd%d req %p tid %llu\n", __func__, osd, osd->o_osd,
+	     req, req->r_tid);
+
+	req->r_osd = NULL;
+	erase_request(&osd->o_requests, req);
+	put_osd(osd);
+
+	if (!osd_homeless(osd))
+		maybe_move_osd_to_lru(osd);
+	else
+		atomic_dec(&osd->o_osdc->num_homeless);
+}
+
+static bool __pool_full(struct ceph_pg_pool_info *pi)
+{
+	return pi->flags & CEPH_POOL_FLAG_FULL;
+}
+
+static bool have_pool_full(struct ceph_osd_client *osdc)
+{
+	struct rb_node *n;
+
+	for (n = rb_first(&osdc->osdmap->pg_pools); n; n = rb_next(n)) {
+		struct ceph_pg_pool_info *pi =
+		    rb_entry(n, struct ceph_pg_pool_info, node);
+
+		if (__pool_full(pi))
+			return true;
+	}
+
+	return false;
+}
+
+static bool pool_full(struct ceph_osd_client *osdc, s64 pool_id)
+{
+	struct ceph_pg_pool_info *pi;
+
+	pi = ceph_pg_pool_by_id(osdc->osdmap, pool_id);
+	if (!pi)
+		return false;
+
+	return __pool_full(pi);
+}
+
+/*
+ * Returns whether a request should be blocked from being sent
+ * based on the current osdmap and osd_client settings.
+ */
+static bool target_should_be_paused(struct ceph_osd_client *osdc,
+				    const struct ceph_osd_request_target *t,
+				    struct ceph_pg_pool_info *pi)
+{
+	bool pauserd = ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSERD);
+	bool pausewr = ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSEWR) ||
+		       ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) ||
+		       __pool_full(pi);
+
+	WARN_ON(pi->id != t->target_oloc.pool);
+	return ((t->flags & CEPH_OSD_FLAG_READ) && pauserd) ||
+	       ((t->flags & CEPH_OSD_FLAG_WRITE) && pausewr) ||
+	       (osdc->osdmap->epoch < osdc->epoch_barrier);
+}
+
+static int pick_random_replica(const struct ceph_osds *acting)
+{
+	int i = prandom_u32() % acting->size;
+
+	dout("%s picked osd%d, primary osd%d\n", __func__,
+	     acting->osds[i], acting->primary);
+	return i;
+}
+
+/*
+ * Picks the closest replica based on client's location given by
+ * crush_location option.  Prefers the primary if the locality is
+ * the same.
+ */
+static int pick_closest_replica(struct ceph_osd_client *osdc,
+				const struct ceph_osds *acting)
+{
+	struct ceph_options *opt = osdc->client->options;
+	int best_i, best_locality;
+	int i = 0, locality;
+
+	do {
+		locality = ceph_get_crush_locality(osdc->osdmap,
+						   acting->osds[i],
+						   &opt->crush_locs);
+		if (i == 0 ||
+		    (locality >= 0 && best_locality < 0) ||
+		    (locality >= 0 && best_locality >= 0 &&
+		     locality < best_locality)) {
+			best_i = i;
+			best_locality = locality;
+		}
+	} while (++i < acting->size);
+
+	dout("%s picked osd%d with locality %d, primary osd%d\n", __func__,
+	     acting->osds[best_i], best_locality, acting->primary);
+	return best_i;
+}
+
+enum calc_target_result {
+	CALC_TARGET_NO_ACTION = 0,
+	CALC_TARGET_NEED_RESEND,
+	CALC_TARGET_POOL_DNE,
+};
+
+static enum calc_target_result calc_target(struct ceph_osd_client *osdc,
+					   struct ceph_osd_request_target *t,
+					   bool any_change)
+{
+	struct ceph_pg_pool_info *pi;
+	struct ceph_pg pgid, last_pgid;
+	struct ceph_osds up, acting;
+	bool is_read = t->flags & CEPH_OSD_FLAG_READ;
+	bool is_write = t->flags & CEPH_OSD_FLAG_WRITE;
+	bool force_resend = false;
+	bool unpaused = false;
+	bool legacy_change = false;
+	bool split = false;
+	bool sort_bitwise = ceph_osdmap_flag(osdc, CEPH_OSDMAP_SORTBITWISE);
+	bool recovery_deletes = ceph_osdmap_flag(osdc,
+						 CEPH_OSDMAP_RECOVERY_DELETES);
+	enum calc_target_result ct_res;
+
+	t->epoch = osdc->osdmap->epoch;
+	pi = ceph_pg_pool_by_id(osdc->osdmap, t->base_oloc.pool);
+	if (!pi) {
+		t->osd = CEPH_HOMELESS_OSD;
+		ct_res = CALC_TARGET_POOL_DNE;
+		goto out;
+	}
+
+	if (osdc->osdmap->epoch == pi->last_force_request_resend) {
+		if (t->last_force_resend < pi->last_force_request_resend) {
+			t->last_force_resend = pi->last_force_request_resend;
+			force_resend = true;
+		} else if (t->last_force_resend == 0) {
+			force_resend = true;
+		}
+	}
+
+	/* apply tiering */
+	ceph_oid_copy(&t->target_oid, &t->base_oid);
+	ceph_oloc_copy(&t->target_oloc, &t->base_oloc);
+	if ((t->flags & CEPH_OSD_FLAG_IGNORE_OVERLAY) == 0) {
+		if (is_read && pi->read_tier >= 0)
+			t->target_oloc.pool = pi->read_tier;
+		if (is_write && pi->write_tier >= 0)
+			t->target_oloc.pool = pi->write_tier;
+
+		pi = ceph_pg_pool_by_id(osdc->osdmap, t->target_oloc.pool);
+		if (!pi) {
+			t->osd = CEPH_HOMELESS_OSD;
+			ct_res = CALC_TARGET_POOL_DNE;
+			goto out;
+		}
+	}
+
+	__ceph_object_locator_to_pg(pi, &t->target_oid, &t->target_oloc, &pgid);
+	last_pgid.pool = pgid.pool;
+	last_pgid.seed = ceph_stable_mod(pgid.seed, t->pg_num, t->pg_num_mask);
+
+	ceph_pg_to_up_acting_osds(osdc->osdmap, pi, &pgid, &up, &acting);
+	if (any_change &&
+	    ceph_is_new_interval(&t->acting,
+				 &acting,
+				 &t->up,
+				 &up,
+				 t->size,
+				 pi->size,
+				 t->min_size,
+				 pi->min_size,
+				 t->pg_num,
+				 pi->pg_num,
+				 t->sort_bitwise,
+				 sort_bitwise,
+				 t->recovery_deletes,
+				 recovery_deletes,
+				 &last_pgid))
+		force_resend = true;
+
+	if (t->paused && !target_should_be_paused(osdc, t, pi)) {
+		t->paused = false;
+		unpaused = true;
+	}
+	legacy_change = ceph_pg_compare(&t->pgid, &pgid) ||
+			ceph_osds_changed(&t->acting, &acting,
+					  t->used_replica || any_change);
+	if (t->pg_num)
+		split = ceph_pg_is_split(&last_pgid, t->pg_num, pi->pg_num);
+
+	if (legacy_change || force_resend || split) {
+		t->pgid = pgid; /* struct */
+		ceph_pg_to_primary_shard(osdc->osdmap, pi, &pgid, &t->spgid);
+		ceph_osds_copy(&t->acting, &acting);
+		ceph_osds_copy(&t->up, &up);
+		t->size = pi->size;
+		t->min_size = pi->min_size;
+		t->pg_num = pi->pg_num;
+		t->pg_num_mask = pi->pg_num_mask;
+		t->sort_bitwise = sort_bitwise;
+		t->recovery_deletes = recovery_deletes;
+
+		if ((t->flags & (CEPH_OSD_FLAG_BALANCE_READS |
+				 CEPH_OSD_FLAG_LOCALIZE_READS)) &&
+		    !is_write && pi->type == CEPH_POOL_TYPE_REP &&
+		    acting.size > 1) {
+			int pos;
+
+			WARN_ON(!is_read || acting.osds[0] != acting.primary);
+			if (t->flags & CEPH_OSD_FLAG_BALANCE_READS) {
+				pos = pick_random_replica(&acting);
+			} else {
+				pos = pick_closest_replica(osdc, &acting);
+			}
+			t->osd = acting.osds[pos];
+			t->used_replica = pos > 0;
+		} else {
+			t->osd = acting.primary;
+			t->used_replica = false;
+		}
+	}
+
+	if (unpaused || legacy_change || force_resend || split)
+		ct_res = CALC_TARGET_NEED_RESEND;
+	else
+		ct_res = CALC_TARGET_NO_ACTION;
+
+out:
+	dout("%s t %p -> %d%d%d%d ct_res %d osd%d\n", __func__, t, unpaused,
+	     legacy_change, force_resend, split, ct_res, t->osd);
+	return ct_res;
+}
+
+static struct ceph_spg_mapping *alloc_spg_mapping(void)
+{
+	struct ceph_spg_mapping *spg;
+
+	spg = kmalloc(sizeof(*spg), GFP_NOIO);
+	if (!spg)
+		return NULL;
+
+	RB_CLEAR_NODE(&spg->node);
+	spg->backoffs = RB_ROOT;
+	return spg;
+}
+
+static void free_spg_mapping(struct ceph_spg_mapping *spg)
+{
+	WARN_ON(!RB_EMPTY_NODE(&spg->node));
+	WARN_ON(!RB_EMPTY_ROOT(&spg->backoffs));
+
+	kfree(spg);
+}
+
+/*
+ * rbtree of ceph_spg_mapping for handling map<spg_t, ...>, similar to
+ * ceph_pg_mapping.  Used to track OSD backoffs -- a backoff [range] is
+ * defined only within a specific spgid; it does not pass anything to
+ * children on split, or to another primary.
+ */
+DEFINE_RB_FUNCS2(spg_mapping, struct ceph_spg_mapping, spgid, ceph_spg_compare,
+		 RB_BYPTR, const struct ceph_spg *, node)
+
+static u64 hoid_get_bitwise_key(const struct ceph_hobject_id *hoid)
+{
+	return hoid->is_max ? 0x100000000ull : hoid->hash_reverse_bits;
+}
+
+static void hoid_get_effective_key(const struct ceph_hobject_id *hoid,
+				   void **pkey, size_t *pkey_len)
+{
+	if (hoid->key_len) {
+		*pkey = hoid->key;
+		*pkey_len = hoid->key_len;
+	} else {
+		*pkey = hoid->oid;
+		*pkey_len = hoid->oid_len;
+	}
+}
+
+static int compare_names(const void *name1, size_t name1_len,
+			 const void *name2, size_t name2_len)
+{
+	int ret;
+
+	ret = memcmp(name1, name2, min(name1_len, name2_len));
+	if (!ret) {
+		if (name1_len < name2_len)
+			ret = -1;
+		else if (name1_len > name2_len)
+			ret = 1;
+	}
+	return ret;
+}
+
+static int hoid_compare(const struct ceph_hobject_id *lhs,
+			const struct ceph_hobject_id *rhs)
+{
+	void *effective_key1, *effective_key2;
+	size_t effective_key1_len, effective_key2_len;
+	int ret;
+
+	if (lhs->is_max < rhs->is_max)
+		return -1;
+	if (lhs->is_max > rhs->is_max)
+		return 1;
+
+	if (lhs->pool < rhs->pool)
+		return -1;
+	if (lhs->pool > rhs->pool)
+		return 1;
+
+	if (hoid_get_bitwise_key(lhs) < hoid_get_bitwise_key(rhs))
+		return -1;
+	if (hoid_get_bitwise_key(lhs) > hoid_get_bitwise_key(rhs))
+		return 1;
+
+	ret = compare_names(lhs->nspace, lhs->nspace_len,
+			    rhs->nspace, rhs->nspace_len);
+	if (ret)
+		return ret;
+
+	hoid_get_effective_key(lhs, &effective_key1, &effective_key1_len);
+	hoid_get_effective_key(rhs, &effective_key2, &effective_key2_len);
+	ret = compare_names(effective_key1, effective_key1_len,
+			    effective_key2, effective_key2_len);
+	if (ret)
+		return ret;
+
+	ret = compare_names(lhs->oid, lhs->oid_len, rhs->oid, rhs->oid_len);
+	if (ret)
+		return ret;
+
+	if (lhs->snapid < rhs->snapid)
+		return -1;
+	if (lhs->snapid > rhs->snapid)
+		return 1;
+
+	return 0;
+}
+
+/*
+ * For decoding ->begin and ->end of MOSDBackoff only -- no MIN/MAX
+ * compat stuff here.
+ *
+ * Assumes @hoid is zero-initialized.
+ */
+static int decode_hoid(void **p, void *end, struct ceph_hobject_id *hoid)
+{
+	u8 struct_v;
+	u32 struct_len;
+	int ret;
+
+	ret = ceph_start_decoding(p, end, 4, "hobject_t", &struct_v,
+				  &struct_len);
+	if (ret)
+		return ret;
+
+	if (struct_v < 4) {
+		pr_err("got struct_v %d < 4 of hobject_t\n", struct_v);
+		goto e_inval;
+	}
+
+	hoid->key = ceph_extract_encoded_string(p, end, &hoid->key_len,
+						GFP_NOIO);
+	if (IS_ERR(hoid->key)) {
+		ret = PTR_ERR(hoid->key);
+		hoid->key = NULL;
+		return ret;
+	}
+
+	hoid->oid = ceph_extract_encoded_string(p, end, &hoid->oid_len,
+						GFP_NOIO);
+	if (IS_ERR(hoid->oid)) {
+		ret = PTR_ERR(hoid->oid);
+		hoid->oid = NULL;
+		return ret;
+	}
+
+	ceph_decode_64_safe(p, end, hoid->snapid, e_inval);
+	ceph_decode_32_safe(p, end, hoid->hash, e_inval);
+	ceph_decode_8_safe(p, end, hoid->is_max, e_inval);
+
+	hoid->nspace = ceph_extract_encoded_string(p, end, &hoid->nspace_len,
+						   GFP_NOIO);
+	if (IS_ERR(hoid->nspace)) {
+		ret = PTR_ERR(hoid->nspace);
+		hoid->nspace = NULL;
+		return ret;
+	}
+
+	ceph_decode_64_safe(p, end, hoid->pool, e_inval);
+
+	ceph_hoid_build_hash_cache(hoid);
+	return 0;
+
+e_inval:
+	return -EINVAL;
+}
+
+static int hoid_encoding_size(const struct ceph_hobject_id *hoid)
+{
+	return 8 + 4 + 1 + 8 + /* snapid, hash, is_max, pool */
+	       4 + hoid->key_len + 4 + hoid->oid_len + 4 + hoid->nspace_len;
+}
+
+static void encode_hoid(void **p, void *end, const struct ceph_hobject_id *hoid)
+{
+	ceph_start_encoding(p, 4, 3, hoid_encoding_size(hoid));
+	ceph_encode_string(p, end, hoid->key, hoid->key_len);
+	ceph_encode_string(p, end, hoid->oid, hoid->oid_len);
+	ceph_encode_64(p, hoid->snapid);
+	ceph_encode_32(p, hoid->hash);
+	ceph_encode_8(p, hoid->is_max);
+	ceph_encode_string(p, end, hoid->nspace, hoid->nspace_len);
+	ceph_encode_64(p, hoid->pool);
+}
+
+static void free_hoid(struct ceph_hobject_id *hoid)
+{
+	if (hoid) {
+		kfree(hoid->key);
+		kfree(hoid->oid);
+		kfree(hoid->nspace);
+		kfree(hoid);
+	}
+}
+
+static struct ceph_osd_backoff *alloc_backoff(void)
+{
+	struct ceph_osd_backoff *backoff;
+
+	backoff = kzalloc(sizeof(*backoff), GFP_NOIO);
+	if (!backoff)
+		return NULL;
+
+	RB_CLEAR_NODE(&backoff->spg_node);
+	RB_CLEAR_NODE(&backoff->id_node);
+	return backoff;
+}
+
+static void free_backoff(struct ceph_osd_backoff *backoff)
+{
+	WARN_ON(!RB_EMPTY_NODE(&backoff->spg_node));
+	WARN_ON(!RB_EMPTY_NODE(&backoff->id_node));
+
+	free_hoid(backoff->begin);
+	free_hoid(backoff->end);
+	kfree(backoff);
+}
+
+/*
+ * Within a specific spgid, backoffs are managed by ->begin hoid.
+ */
+DEFINE_RB_INSDEL_FUNCS2(backoff, struct ceph_osd_backoff, begin, hoid_compare,
+			RB_BYVAL, spg_node);
+
+static struct ceph_osd_backoff *lookup_containing_backoff(struct rb_root *root,
+					    const struct ceph_hobject_id *hoid)
+{
+	struct rb_node *n = root->rb_node;
+
+	while (n) {
+		struct ceph_osd_backoff *cur =
+		    rb_entry(n, struct ceph_osd_backoff, spg_node);
+		int cmp;
+
+		cmp = hoid_compare(hoid, cur->begin);
+		if (cmp < 0) {
+			n = n->rb_left;
+		} else if (cmp > 0) {
+			if (hoid_compare(hoid, cur->end) < 0)
+				return cur;
+
+			n = n->rb_right;
+		} else {
+			return cur;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * Each backoff has a unique id within its OSD session.
+ */
+DEFINE_RB_FUNCS(backoff_by_id, struct ceph_osd_backoff, id, id_node)
+
+static void clear_backoffs(struct ceph_osd *osd)
+{
+	while (!RB_EMPTY_ROOT(&osd->o_backoff_mappings)) {
+		struct ceph_spg_mapping *spg =
+		    rb_entry(rb_first(&osd->o_backoff_mappings),
+			     struct ceph_spg_mapping, node);
+
+		while (!RB_EMPTY_ROOT(&spg->backoffs)) {
+			struct ceph_osd_backoff *backoff =
+			    rb_entry(rb_first(&spg->backoffs),
+				     struct ceph_osd_backoff, spg_node);
+
+			erase_backoff(&spg->backoffs, backoff);
+			erase_backoff_by_id(&osd->o_backoffs_by_id, backoff);
+			free_backoff(backoff);
+		}
+		erase_spg_mapping(&osd->o_backoff_mappings, spg);
+		free_spg_mapping(spg);
+	}
+}
+
+/*
+ * Set up a temporary, non-owning view into @t.
+ */
+static void hoid_fill_from_target(struct ceph_hobject_id *hoid,
+				  const struct ceph_osd_request_target *t)
+{
+	hoid->key = NULL;
+	hoid->key_len = 0;
+	hoid->oid = t->target_oid.name;
+	hoid->oid_len = t->target_oid.name_len;
+	hoid->snapid = CEPH_NOSNAP;
+	hoid->hash = t->pgid.seed;
+	hoid->is_max = false;
+	if (t->target_oloc.pool_ns) {
+		hoid->nspace = t->target_oloc.pool_ns->str;
+		hoid->nspace_len = t->target_oloc.pool_ns->len;
+	} else {
+		hoid->nspace = NULL;
+		hoid->nspace_len = 0;
+	}
+	hoid->pool = t->target_oloc.pool;
+	ceph_hoid_build_hash_cache(hoid);
+}
+
+static bool should_plug_request(struct ceph_osd_request *req)
+{
+	struct ceph_osd *osd = req->r_osd;
+	struct ceph_spg_mapping *spg;
+	struct ceph_osd_backoff *backoff;
+	struct ceph_hobject_id hoid;
+
+	spg = lookup_spg_mapping(&osd->o_backoff_mappings, &req->r_t.spgid);
+	if (!spg)
+		return false;
+
+	hoid_fill_from_target(&hoid, &req->r_t);
+	backoff = lookup_containing_backoff(&spg->backoffs, &hoid);
+	if (!backoff)
+		return false;
+
+	dout("%s req %p tid %llu backoff osd%d spgid %llu.%xs%d id %llu\n",
+	     __func__, req, req->r_tid, osd->o_osd, backoff->spgid.pgid.pool,
+	     backoff->spgid.pgid.seed, backoff->spgid.shard, backoff->id);
+	return true;
+}
+
+/*
+ * Keep get_num_data_items() in sync with this function.
+ */
+static void setup_request_data(struct ceph_osd_request *req)
+{
+	struct ceph_msg *request_msg = req->r_request;
+	struct ceph_msg *reply_msg = req->r_reply;
+	struct ceph_osd_req_op *op;
+
+	if (req->r_request->num_data_items || req->r_reply->num_data_items)
+		return;
+
+	WARN_ON(request_msg->data_length || reply_msg->data_length);
+	for (op = req->r_ops; op != &req->r_ops[req->r_num_ops]; op++) {
+		switch (op->op) {
+		/* request */
+		case CEPH_OSD_OP_WRITE:
+		case CEPH_OSD_OP_WRITEFULL:
+			WARN_ON(op->indata_len != op->extent.length);
+			ceph_osdc_msg_data_add(request_msg,
+					       &op->extent.osd_data);
+			break;
+		case CEPH_OSD_OP_SETXATTR:
+		case CEPH_OSD_OP_CMPXATTR:
+			WARN_ON(op->indata_len != op->xattr.name_len +
+						  op->xattr.value_len);
+			ceph_osdc_msg_data_add(request_msg,
+					       &op->xattr.osd_data);
+			break;
+		case CEPH_OSD_OP_NOTIFY_ACK:
+			ceph_osdc_msg_data_add(request_msg,
+					       &op->notify_ack.request_data);
+			break;
+		case CEPH_OSD_OP_COPY_FROM2:
+			ceph_osdc_msg_data_add(request_msg,
+					       &op->copy_from.osd_data);
+			break;
+
+		/* reply */
+		case CEPH_OSD_OP_STAT:
+			ceph_osdc_msg_data_add(reply_msg,
+					       &op->raw_data_in);
+			break;
+		case CEPH_OSD_OP_READ:
+			ceph_osdc_msg_data_add(reply_msg,
+					       &op->extent.osd_data);
+			break;
+		case CEPH_OSD_OP_LIST_WATCHERS:
+			ceph_osdc_msg_data_add(reply_msg,
+					       &op->list_watchers.response_data);
+			break;
+
+		/* both */
+		case CEPH_OSD_OP_CALL:
+			WARN_ON(op->indata_len != op->cls.class_len +
+						  op->cls.method_len +
+						  op->cls.indata_len);
+			ceph_osdc_msg_data_add(request_msg,
+					       &op->cls.request_info);
+			/* optional, can be NONE */
+			ceph_osdc_msg_data_add(request_msg,
+					       &op->cls.request_data);
+			/* optional, can be NONE */
+			ceph_osdc_msg_data_add(reply_msg,
+					       &op->cls.response_data);
+			break;
+		case CEPH_OSD_OP_NOTIFY:
+			ceph_osdc_msg_data_add(request_msg,
+					       &op->notify.request_data);
+			ceph_osdc_msg_data_add(reply_msg,
+					       &op->notify.response_data);
+			break;
+		}
+	}
+}
+
+static void encode_pgid(void **p, const struct ceph_pg *pgid)
+{
+	ceph_encode_8(p, 1);
+	ceph_encode_64(p, pgid->pool);
+	ceph_encode_32(p, pgid->seed);
+	ceph_encode_32(p, -1); /* preferred */
+}
+
+static void encode_spgid(void **p, const struct ceph_spg *spgid)
+{
+	ceph_start_encoding(p, 1, 1, CEPH_PGID_ENCODING_LEN + 1);
+	encode_pgid(p, &spgid->pgid);
+	ceph_encode_8(p, spgid->shard);
+}
+
+static void encode_oloc(void **p, void *end,
+			const struct ceph_object_locator *oloc)
+{
+	ceph_start_encoding(p, 5, 4, ceph_oloc_encoding_size(oloc));
+	ceph_encode_64(p, oloc->pool);
+	ceph_encode_32(p, -1); /* preferred */
+	ceph_encode_32(p, 0);  /* key len */
+	if (oloc->pool_ns)
+		ceph_encode_string(p, end, oloc->pool_ns->str,
+				   oloc->pool_ns->len);
+	else
+		ceph_encode_32(p, 0);
+}
+
+static void encode_request_partial(struct ceph_osd_request *req,
+				   struct ceph_msg *msg)
+{
+	void *p = msg->front.iov_base;
+	void *const end = p + msg->front_alloc_len;
+	u32 data_len = 0;
+	int i;
+
+	if (req->r_flags & CEPH_OSD_FLAG_WRITE) {
+		/* snapshots aren't writeable */
+		WARN_ON(req->r_snapid != CEPH_NOSNAP);
+	} else {
+		WARN_ON(req->r_mtime.tv_sec || req->r_mtime.tv_nsec ||
+			req->r_data_offset || req->r_snapc);
+	}
+
+	setup_request_data(req);
+
+	encode_spgid(&p, &req->r_t.spgid); /* actual spg */
+	ceph_encode_32(&p, req->r_t.pgid.seed); /* raw hash */
+	ceph_encode_32(&p, req->r_osdc->osdmap->epoch);
+	ceph_encode_32(&p, req->r_flags);
+
+	/* reqid */
+	ceph_start_encoding(&p, 2, 2, sizeof(struct ceph_osd_reqid));
+	memset(p, 0, sizeof(struct ceph_osd_reqid));
+	p += sizeof(struct ceph_osd_reqid);
+
+	/* trace */
+	memset(p, 0, sizeof(struct ceph_blkin_trace_info));
+	p += sizeof(struct ceph_blkin_trace_info);
+
+	ceph_encode_32(&p, 0); /* client_inc, always 0 */
+	ceph_encode_timespec64(p, &req->r_mtime);
+	p += sizeof(struct ceph_timespec);
+
+	encode_oloc(&p, end, &req->r_t.target_oloc);
+	ceph_encode_string(&p, end, req->r_t.target_oid.name,
+			   req->r_t.target_oid.name_len);
+
+	/* ops, can imply data */
+	ceph_encode_16(&p, req->r_num_ops);
+	for (i = 0; i < req->r_num_ops; i++) {
+		data_len += osd_req_encode_op(p, &req->r_ops[i]);
+		p += sizeof(struct ceph_osd_op);
+	}
+
+	ceph_encode_64(&p, req->r_snapid); /* snapid */
+	if (req->r_snapc) {
+		ceph_encode_64(&p, req->r_snapc->seq);
+		ceph_encode_32(&p, req->r_snapc->num_snaps);
+		for (i = 0; i < req->r_snapc->num_snaps; i++)
+			ceph_encode_64(&p, req->r_snapc->snaps[i]);
+	} else {
+		ceph_encode_64(&p, 0); /* snap_seq */
+		ceph_encode_32(&p, 0); /* snaps len */
+	}
+
+	ceph_encode_32(&p, req->r_attempts); /* retry_attempt */
+	BUG_ON(p > end - 8); /* space for features */
+
+	msg->hdr.version = cpu_to_le16(8); /* MOSDOp v8 */
+	/* front_len is finalized in encode_request_finish() */
+	msg->front.iov_len = p - msg->front.iov_base;
+	msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
+	msg->hdr.data_len = cpu_to_le32(data_len);
+	/*
+	 * The header "data_off" is a hint to the receiver allowing it
+	 * to align received data into its buffers such that there's no
+	 * need to re-copy it before writing it to disk (direct I/O).
+	 */
+	msg->hdr.data_off = cpu_to_le16(req->r_data_offset);
+
+	dout("%s req %p msg %p oid %s oid_len %d\n", __func__, req, msg,
+	     req->r_t.target_oid.name, req->r_t.target_oid.name_len);
+}
+
+static void encode_request_finish(struct ceph_msg *msg)
+{
+	void *p = msg->front.iov_base;
+	void *const partial_end = p + msg->front.iov_len;
+	void *const end = p + msg->front_alloc_len;
+
+	if (CEPH_HAVE_FEATURE(msg->con->peer_features, RESEND_ON_SPLIT)) {
+		/* luminous OSD -- encode features and be done */
+		p = partial_end;
+		ceph_encode_64(&p, msg->con->peer_features);
+	} else {
+		struct {
+			char spgid[CEPH_ENCODING_START_BLK_LEN +
+				   CEPH_PGID_ENCODING_LEN + 1];
+			__le32 hash;
+			__le32 epoch;
+			__le32 flags;
+			char reqid[CEPH_ENCODING_START_BLK_LEN +
+				   sizeof(struct ceph_osd_reqid)];
+			char trace[sizeof(struct ceph_blkin_trace_info)];
+			__le32 client_inc;
+			struct ceph_timespec mtime;
+		} __packed head;
+		struct ceph_pg pgid;
+		void *oloc, *oid, *tail;
+		int oloc_len, oid_len, tail_len;
+		int len;
+
+		/*
+		 * Pre-luminous OSD -- reencode v8 into v4 using @head
+		 * as a temporary buffer.  Encode the raw PG; the rest
+		 * is just a matter of moving oloc, oid and tail blobs
+		 * around.
+		 */
+		memcpy(&head, p, sizeof(head));
+		p += sizeof(head);
+
+		oloc = p;
+		p += CEPH_ENCODING_START_BLK_LEN;
+		pgid.pool = ceph_decode_64(&p);
+		p += 4 + 4; /* preferred, key len */
+		len = ceph_decode_32(&p);
+		p += len;   /* nspace */
+		oloc_len = p - oloc;
+
+		oid = p;
+		len = ceph_decode_32(&p);
+		p += len;
+		oid_len = p - oid;
+
+		tail = p;
+		tail_len = partial_end - p;
+
+		p = msg->front.iov_base;
+		ceph_encode_copy(&p, &head.client_inc, sizeof(head.client_inc));
+		ceph_encode_copy(&p, &head.epoch, sizeof(head.epoch));
+		ceph_encode_copy(&p, &head.flags, sizeof(head.flags));
+		ceph_encode_copy(&p, &head.mtime, sizeof(head.mtime));
+
+		/* reassert_version */
+		memset(p, 0, sizeof(struct ceph_eversion));
+		p += sizeof(struct ceph_eversion);
+
+		BUG_ON(p >= oloc);
+		memmove(p, oloc, oloc_len);
+		p += oloc_len;
+
+		pgid.seed = le32_to_cpu(head.hash);
+		encode_pgid(&p, &pgid); /* raw pg */
+
+		BUG_ON(p >= oid);
+		memmove(p, oid, oid_len);
+		p += oid_len;
+
+		/* tail -- ops, snapid, snapc, retry_attempt */
+		BUG_ON(p >= tail);
+		memmove(p, tail, tail_len);
+		p += tail_len;
+
+		msg->hdr.version = cpu_to_le16(4); /* MOSDOp v4 */
+	}
+
+	BUG_ON(p > end);
+	msg->front.iov_len = p - msg->front.iov_base;
+	msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
+
+	dout("%s msg %p tid %llu %u+%u+%u v%d\n", __func__, msg,
+	     le64_to_cpu(msg->hdr.tid), le32_to_cpu(msg->hdr.front_len),
+	     le32_to_cpu(msg->hdr.middle_len), le32_to_cpu(msg->hdr.data_len),
+	     le16_to_cpu(msg->hdr.version));
+}
+
+/*
+ * @req has to be assigned a tid and registered.
+ */
+static void send_request(struct ceph_osd_request *req)
+{
+	struct ceph_osd *osd = req->r_osd;
+
+	verify_osd_locked(osd);
+	WARN_ON(osd->o_osd != req->r_t.osd);
+
+	/* backoff? */
+	if (should_plug_request(req))
+		return;
+
+	/*
+	 * We may have a previously queued request message hanging
+	 * around.  Cancel it to avoid corrupting the msgr.
+	 */
+	if (req->r_sent)
+		ceph_msg_revoke(req->r_request);
+
+	req->r_flags |= CEPH_OSD_FLAG_KNOWN_REDIR;
+	if (req->r_attempts)
+		req->r_flags |= CEPH_OSD_FLAG_RETRY;
+	else
+		WARN_ON(req->r_flags & CEPH_OSD_FLAG_RETRY);
+
+	encode_request_partial(req, req->r_request);
+
+	dout("%s req %p tid %llu to pgid %llu.%x spgid %llu.%xs%d osd%d e%u flags 0x%x attempt %d\n",
+	     __func__, req, req->r_tid, req->r_t.pgid.pool, req->r_t.pgid.seed,
+	     req->r_t.spgid.pgid.pool, req->r_t.spgid.pgid.seed,
+	     req->r_t.spgid.shard, osd->o_osd, req->r_t.epoch, req->r_flags,
+	     req->r_attempts);
+
+	req->r_t.paused = false;
+	req->r_stamp = jiffies;
+	req->r_attempts++;
+
+	req->r_sent = osd->o_incarnation;
+	req->r_request->hdr.tid = cpu_to_le64(req->r_tid);
+	ceph_con_send(&osd->o_con, ceph_msg_get(req->r_request));
+}
+
+static void maybe_request_map(struct ceph_osd_client *osdc)
+{
+	bool continuous = false;
+
+	verify_osdc_locked(osdc);
+	WARN_ON(!osdc->osdmap->epoch);
+
+	if (ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) ||
+	    ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSERD) ||
+	    ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSEWR)) {
+		dout("%s osdc %p continuous\n", __func__, osdc);
+		continuous = true;
+	} else {
+		dout("%s osdc %p onetime\n", __func__, osdc);
+	}
+
+	if (ceph_monc_want_map(&osdc->client->monc, CEPH_SUB_OSDMAP,
+			       osdc->osdmap->epoch + 1, continuous))
+		ceph_monc_renew_subs(&osdc->client->monc);
+}
+
+static void complete_request(struct ceph_osd_request *req, int err);
+static void send_map_check(struct ceph_osd_request *req);
+
+static void __submit_request(struct ceph_osd_request *req, bool wrlocked)
+{
+	struct ceph_osd_client *osdc = req->r_osdc;
+	struct ceph_osd *osd;
+	enum calc_target_result ct_res;
+	int err = 0;
+	bool need_send = false;
+	bool promoted = false;
+
+	WARN_ON(req->r_tid);
+	dout("%s req %p wrlocked %d\n", __func__, req, wrlocked);
+
+again:
+	ct_res = calc_target(osdc, &req->r_t, false);
+	if (ct_res == CALC_TARGET_POOL_DNE && !wrlocked)
+		goto promote;
+
+	osd = lookup_create_osd(osdc, req->r_t.osd, wrlocked);
+	if (IS_ERR(osd)) {
+		WARN_ON(PTR_ERR(osd) != -EAGAIN || wrlocked);
+		goto promote;
+	}
+
+	if (osdc->abort_err) {
+		dout("req %p abort_err %d\n", req, osdc->abort_err);
+		err = osdc->abort_err;
+	} else if (osdc->osdmap->epoch < osdc->epoch_barrier) {
+		dout("req %p epoch %u barrier %u\n", req, osdc->osdmap->epoch,
+		     osdc->epoch_barrier);
+		req->r_t.paused = true;
+		maybe_request_map(osdc);
+	} else if ((req->r_flags & CEPH_OSD_FLAG_WRITE) &&
+		   ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSEWR)) {
+		dout("req %p pausewr\n", req);
+		req->r_t.paused = true;
+		maybe_request_map(osdc);
+	} else if ((req->r_flags & CEPH_OSD_FLAG_READ) &&
+		   ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSERD)) {
+		dout("req %p pauserd\n", req);
+		req->r_t.paused = true;
+		maybe_request_map(osdc);
+	} else if ((req->r_flags & CEPH_OSD_FLAG_WRITE) &&
+		   !(req->r_flags & (CEPH_OSD_FLAG_FULL_TRY |
+				     CEPH_OSD_FLAG_FULL_FORCE)) &&
+		   (ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) ||
+		    pool_full(osdc, req->r_t.base_oloc.pool))) {
+		dout("req %p full/pool_full\n", req);
+		if (ceph_test_opt(osdc->client, ABORT_ON_FULL)) {
+			err = -ENOSPC;
+		} else {
+			pr_warn_ratelimited("FULL or reached pool quota\n");
+			req->r_t.paused = true;
+			maybe_request_map(osdc);
+		}
+	} else if (!osd_homeless(osd)) {
+		need_send = true;
+	} else {
+		maybe_request_map(osdc);
+	}
+
+	mutex_lock(&osd->lock);
+	/*
+	 * Assign the tid atomically with send_request() to protect
+	 * multiple writes to the same object from racing with each
+	 * other, resulting in out of order ops on the OSDs.
+	 */
+	req->r_tid = atomic64_inc_return(&osdc->last_tid);
+	link_request(osd, req);
+	if (need_send)
+		send_request(req);
+	else if (err)
+		complete_request(req, err);
+	mutex_unlock(&osd->lock);
+
+	if (!err && ct_res == CALC_TARGET_POOL_DNE)
+		send_map_check(req);
+
+	if (promoted)
+		downgrade_write(&osdc->lock);
+	return;
+
+promote:
+	up_read(&osdc->lock);
+	down_write(&osdc->lock);
+	wrlocked = true;
+	promoted = true;
+	goto again;
+}
+
+static void account_request(struct ceph_osd_request *req)
+{
+	WARN_ON(req->r_flags & (CEPH_OSD_FLAG_ACK | CEPH_OSD_FLAG_ONDISK));
+	WARN_ON(!(req->r_flags & (CEPH_OSD_FLAG_READ | CEPH_OSD_FLAG_WRITE)));
+
+	req->r_flags |= CEPH_OSD_FLAG_ONDISK;
+	atomic_inc(&req->r_osdc->num_requests);
+
+	req->r_start_stamp = jiffies;
+	req->r_start_latency = ktime_get();
+}
+
+static void submit_request(struct ceph_osd_request *req, bool wrlocked)
+{
+	ceph_osdc_get_request(req);
+	account_request(req);
+	__submit_request(req, wrlocked);
+}
+
+static void finish_request(struct ceph_osd_request *req)
+{
+	struct ceph_osd_client *osdc = req->r_osdc;
+
+	WARN_ON(lookup_request_mc(&osdc->map_checks, req->r_tid));
+	dout("%s req %p tid %llu\n", __func__, req, req->r_tid);
+
+	req->r_end_latency = ktime_get();
+
+	if (req->r_osd)
+		unlink_request(req->r_osd, req);
+	atomic_dec(&osdc->num_requests);
+
+	/*
+	 * If an OSD has failed or returned and a request has been sent
+	 * twice, it's possible to get a reply and end up here while the
+	 * request message is queued for delivery.  We will ignore the
+	 * reply, so not a big deal, but better to try and catch it.
+	 */
+	ceph_msg_revoke(req->r_request);
+	ceph_msg_revoke_incoming(req->r_reply);
+}
+
+static void __complete_request(struct ceph_osd_request *req)
+{
+	dout("%s req %p tid %llu cb %ps result %d\n", __func__, req,
+	     req->r_tid, req->r_callback, req->r_result);
+
+	if (req->r_callback)
+		req->r_callback(req);
+	complete_all(&req->r_completion);
+	ceph_osdc_put_request(req);
+}
+
+static void complete_request_workfn(struct work_struct *work)
+{
+	struct ceph_osd_request *req =
+	    container_of(work, struct ceph_osd_request, r_complete_work);
+
+	__complete_request(req);
+}
+
+/*
+ * This is open-coded in handle_reply().
+ */
+static void complete_request(struct ceph_osd_request *req, int err)
+{
+	dout("%s req %p tid %llu err %d\n", __func__, req, req->r_tid, err);
+
+	req->r_result = err;
+	finish_request(req);
+
+	INIT_WORK(&req->r_complete_work, complete_request_workfn);
+	queue_work(req->r_osdc->completion_wq, &req->r_complete_work);
+}
+
+static void cancel_map_check(struct ceph_osd_request *req)
+{
+	struct ceph_osd_client *osdc = req->r_osdc;
+	struct ceph_osd_request *lookup_req;
+
+	verify_osdc_wrlocked(osdc);
+
+	lookup_req = lookup_request_mc(&osdc->map_checks, req->r_tid);
+	if (!lookup_req)
+		return;
+
+	WARN_ON(lookup_req != req);
+	erase_request_mc(&osdc->map_checks, req);
+	ceph_osdc_put_request(req);
+}
+
+static void cancel_request(struct ceph_osd_request *req)
+{
+	dout("%s req %p tid %llu\n", __func__, req, req->r_tid);
+
+	cancel_map_check(req);
+	finish_request(req);
+	complete_all(&req->r_completion);
+	ceph_osdc_put_request(req);
+}
+
+static void abort_request(struct ceph_osd_request *req, int err)
+{
+	dout("%s req %p tid %llu err %d\n", __func__, req, req->r_tid, err);
+
+	cancel_map_check(req);
+	complete_request(req, err);
+}
+
+static int abort_fn(struct ceph_osd_request *req, void *arg)
+{
+	int err = *(int *)arg;
+
+	abort_request(req, err);
+	return 0; /* continue iteration */
+}
+
+/*
+ * Abort all in-flight requests with @err and arrange for all future
+ * requests to be failed immediately.
+ */
+void ceph_osdc_abort_requests(struct ceph_osd_client *osdc, int err)
+{
+	dout("%s osdc %p err %d\n", __func__, osdc, err);
+	down_write(&osdc->lock);
+	for_each_request(osdc, abort_fn, &err);
+	osdc->abort_err = err;
+	up_write(&osdc->lock);
+}
+EXPORT_SYMBOL(ceph_osdc_abort_requests);
+
+void ceph_osdc_clear_abort_err(struct ceph_osd_client *osdc)
+{
+	down_write(&osdc->lock);
+	osdc->abort_err = 0;
+	up_write(&osdc->lock);
+}
+EXPORT_SYMBOL(ceph_osdc_clear_abort_err);
+
+static void update_epoch_barrier(struct ceph_osd_client *osdc, u32 eb)
+{
+	if (likely(eb > osdc->epoch_barrier)) {
+		dout("updating epoch_barrier from %u to %u\n",
+				osdc->epoch_barrier, eb);
+		osdc->epoch_barrier = eb;
+		/* Request map if we're not to the barrier yet */
+		if (eb > osdc->osdmap->epoch)
+			maybe_request_map(osdc);
+	}
+}
+
+void ceph_osdc_update_epoch_barrier(struct ceph_osd_client *osdc, u32 eb)
+{
+	down_read(&osdc->lock);
+	if (unlikely(eb > osdc->epoch_barrier)) {
+		up_read(&osdc->lock);
+		down_write(&osdc->lock);
+		update_epoch_barrier(osdc, eb);
+		up_write(&osdc->lock);
+	} else {
+		up_read(&osdc->lock);
+	}
+}
+EXPORT_SYMBOL(ceph_osdc_update_epoch_barrier);
+
+/*
+ * We can end up releasing caps as a result of abort_request().
+ * In that case, we probably want to ensure that the cap release message
+ * has an updated epoch barrier in it, so set the epoch barrier prior to
+ * aborting the first request.
+ */
+static int abort_on_full_fn(struct ceph_osd_request *req, void *arg)
+{
+	struct ceph_osd_client *osdc = req->r_osdc;
+	bool *victims = arg;
+
+	if ((req->r_flags & CEPH_OSD_FLAG_WRITE) &&
+	    (ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) ||
+	     pool_full(osdc, req->r_t.base_oloc.pool))) {
+		if (!*victims) {
+			update_epoch_barrier(osdc, osdc->osdmap->epoch);
+			*victims = true;
+		}
+		abort_request(req, -ENOSPC);
+	}
+
+	return 0; /* continue iteration */
+}
+
+/*
+ * Drop all pending requests that are stalled waiting on a full condition to
+ * clear, and complete them with ENOSPC as the return code. Set the
+ * osdc->epoch_barrier to the latest map epoch that we've seen if any were
+ * cancelled.
+ */
+static void ceph_osdc_abort_on_full(struct ceph_osd_client *osdc)
+{
+	bool victims = false;
+
+	if (ceph_test_opt(osdc->client, ABORT_ON_FULL) &&
+	    (ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) || have_pool_full(osdc)))
+		for_each_request(osdc, abort_on_full_fn, &victims);
+}
+
+static void check_pool_dne(struct ceph_osd_request *req)
+{
+	struct ceph_osd_client *osdc = req->r_osdc;
+	struct ceph_osdmap *map = osdc->osdmap;
+
+	verify_osdc_wrlocked(osdc);
+	WARN_ON(!map->epoch);
+
+	if (req->r_attempts) {
+		/*
+		 * We sent a request earlier, which means that
+		 * previously the pool existed, and now it does not
+		 * (i.e., it was deleted).
+		 */
+		req->r_map_dne_bound = map->epoch;
+		dout("%s req %p tid %llu pool disappeared\n", __func__, req,
+		     req->r_tid);
+	} else {
+		dout("%s req %p tid %llu map_dne_bound %u have %u\n", __func__,
+		     req, req->r_tid, req->r_map_dne_bound, map->epoch);
+	}
+
+	if (req->r_map_dne_bound) {
+		if (map->epoch >= req->r_map_dne_bound) {
+			/* we had a new enough map */
+			pr_info_ratelimited("tid %llu pool does not exist\n",
+					    req->r_tid);
+			complete_request(req, -ENOENT);
+		}
+	} else {
+		send_map_check(req);
+	}
+}
+
+static void map_check_cb(struct ceph_mon_generic_request *greq)
+{
+	struct ceph_osd_client *osdc = &greq->monc->client->osdc;
+	struct ceph_osd_request *req;
+	u64 tid = greq->private_data;
+
+	WARN_ON(greq->result || !greq->u.newest);
+
+	down_write(&osdc->lock);
+	req = lookup_request_mc(&osdc->map_checks, tid);
+	if (!req) {
+		dout("%s tid %llu dne\n", __func__, tid);
+		goto out_unlock;
+	}
+
+	dout("%s req %p tid %llu map_dne_bound %u newest %llu\n", __func__,
+	     req, req->r_tid, req->r_map_dne_bound, greq->u.newest);
+	if (!req->r_map_dne_bound)
+		req->r_map_dne_bound = greq->u.newest;
+	erase_request_mc(&osdc->map_checks, req);
+	check_pool_dne(req);
+
+	ceph_osdc_put_request(req);
+out_unlock:
+	up_write(&osdc->lock);
+}
+
+static void send_map_check(struct ceph_osd_request *req)
+{
+	struct ceph_osd_client *osdc = req->r_osdc;
+	struct ceph_osd_request *lookup_req;
+	int ret;
+
+	verify_osdc_wrlocked(osdc);
+
+	lookup_req = lookup_request_mc(&osdc->map_checks, req->r_tid);
+	if (lookup_req) {
+		WARN_ON(lookup_req != req);
+		return;
+	}
+
+	ceph_osdc_get_request(req);
+	insert_request_mc(&osdc->map_checks, req);
+	ret = ceph_monc_get_version_async(&osdc->client->monc, "osdmap",
+					  map_check_cb, req->r_tid);
+	WARN_ON(ret);
+}
+
+/*
+ * lingering requests, watch/notify v2 infrastructure
+ */
+static void linger_release(struct kref *kref)
+{
+	struct ceph_osd_linger_request *lreq =
+	    container_of(kref, struct ceph_osd_linger_request, kref);
+
+	dout("%s lreq %p reg_req %p ping_req %p\n", __func__, lreq,
+	     lreq->reg_req, lreq->ping_req);
+	WARN_ON(!RB_EMPTY_NODE(&lreq->node));
+	WARN_ON(!RB_EMPTY_NODE(&lreq->osdc_node));
+	WARN_ON(!RB_EMPTY_NODE(&lreq->mc_node));
+	WARN_ON(!list_empty(&lreq->scan_item));
+	WARN_ON(!list_empty(&lreq->pending_lworks));
+	WARN_ON(lreq->osd);
+
+	if (lreq->request_pl)
+		ceph_pagelist_release(lreq->request_pl);
+	if (lreq->notify_id_pages)
+		ceph_release_page_vector(lreq->notify_id_pages, 1);
+
+	ceph_osdc_put_request(lreq->reg_req);
+	ceph_osdc_put_request(lreq->ping_req);
+	target_destroy(&lreq->t);
+	kfree(lreq);
+}
+
+static void linger_put(struct ceph_osd_linger_request *lreq)
+{
+	if (lreq)
+		kref_put(&lreq->kref, linger_release);
+}
+
+static struct ceph_osd_linger_request *
+linger_get(struct ceph_osd_linger_request *lreq)
+{
+	kref_get(&lreq->kref);
+	return lreq;
+}
+
+static struct ceph_osd_linger_request *
+linger_alloc(struct ceph_osd_client *osdc)
+{
+	struct ceph_osd_linger_request *lreq;
+
+	lreq = kzalloc(sizeof(*lreq), GFP_NOIO);
+	if (!lreq)
+		return NULL;
+
+	kref_init(&lreq->kref);
+	mutex_init(&lreq->lock);
+	RB_CLEAR_NODE(&lreq->node);
+	RB_CLEAR_NODE(&lreq->osdc_node);
+	RB_CLEAR_NODE(&lreq->mc_node);
+	INIT_LIST_HEAD(&lreq->scan_item);
+	INIT_LIST_HEAD(&lreq->pending_lworks);
+	init_completion(&lreq->reg_commit_wait);
+	init_completion(&lreq->notify_finish_wait);
+
+	lreq->osdc = osdc;
+	target_init(&lreq->t);
+
+	dout("%s lreq %p\n", __func__, lreq);
+	return lreq;
+}
+
+DEFINE_RB_INSDEL_FUNCS(linger, struct ceph_osd_linger_request, linger_id, node)
+DEFINE_RB_FUNCS(linger_osdc, struct ceph_osd_linger_request, linger_id, osdc_node)
+DEFINE_RB_FUNCS(linger_mc, struct ceph_osd_linger_request, linger_id, mc_node)
+
+/*
+ * Create linger request <-> OSD session relation.
+ *
+ * @lreq has to be registered, @osd may be homeless.
+ */
+static void link_linger(struct ceph_osd *osd,
+			struct ceph_osd_linger_request *lreq)
+{
+	verify_osd_locked(osd);
+	WARN_ON(!lreq->linger_id || lreq->osd);
+	dout("%s osd %p osd%d lreq %p linger_id %llu\n", __func__, osd,
+	     osd->o_osd, lreq, lreq->linger_id);
+
+	if (!osd_homeless(osd))
+		__remove_osd_from_lru(osd);
+	else
+		atomic_inc(&osd->o_osdc->num_homeless);
+
+	get_osd(osd);
+	insert_linger(&osd->o_linger_requests, lreq);
+	lreq->osd = osd;
+}
+
+static void unlink_linger(struct ceph_osd *osd,
+			  struct ceph_osd_linger_request *lreq)
+{
+	verify_osd_locked(osd);
+	WARN_ON(lreq->osd != osd);
+	dout("%s osd %p osd%d lreq %p linger_id %llu\n", __func__, osd,
+	     osd->o_osd, lreq, lreq->linger_id);
+
+	lreq->osd = NULL;
+	erase_linger(&osd->o_linger_requests, lreq);
+	put_osd(osd);
+
+	if (!osd_homeless(osd))
+		maybe_move_osd_to_lru(osd);
+	else
+		atomic_dec(&osd->o_osdc->num_homeless);
+}
+
+static bool __linger_registered(struct ceph_osd_linger_request *lreq)
+{
+	verify_osdc_locked(lreq->osdc);
+
+	return !RB_EMPTY_NODE(&lreq->osdc_node);
+}
+
+static bool linger_registered(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+	bool registered;
+
+	down_read(&osdc->lock);
+	registered = __linger_registered(lreq);
+	up_read(&osdc->lock);
+
+	return registered;
+}
+
+static void linger_register(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+
+	verify_osdc_wrlocked(osdc);
+	WARN_ON(lreq->linger_id);
+
+	linger_get(lreq);
+	lreq->linger_id = ++osdc->last_linger_id;
+	insert_linger_osdc(&osdc->linger_requests, lreq);
+}
+
+static void linger_unregister(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+
+	verify_osdc_wrlocked(osdc);
+
+	erase_linger_osdc(&osdc->linger_requests, lreq);
+	linger_put(lreq);
+}
+
+static void cancel_linger_request(struct ceph_osd_request *req)
+{
+	struct ceph_osd_linger_request *lreq = req->r_priv;
+
+	WARN_ON(!req->r_linger);
+	cancel_request(req);
+	linger_put(lreq);
+}
+
+struct linger_work {
+	struct work_struct work;
+	struct ceph_osd_linger_request *lreq;
+	struct list_head pending_item;
+	unsigned long queued_stamp;
+
+	union {
+		struct {
+			u64 notify_id;
+			u64 notifier_id;
+			void *payload; /* points into @msg front */
+			size_t payload_len;
+
+			struct ceph_msg *msg; /* for ceph_msg_put() */
+		} notify;
+		struct {
+			int err;
+		} error;
+	};
+};
+
+static struct linger_work *lwork_alloc(struct ceph_osd_linger_request *lreq,
+				       work_func_t workfn)
+{
+	struct linger_work *lwork;
+
+	lwork = kzalloc(sizeof(*lwork), GFP_NOIO);
+	if (!lwork)
+		return NULL;
+
+	INIT_WORK(&lwork->work, workfn);
+	INIT_LIST_HEAD(&lwork->pending_item);
+	lwork->lreq = linger_get(lreq);
+
+	return lwork;
+}
+
+static void lwork_free(struct linger_work *lwork)
+{
+	struct ceph_osd_linger_request *lreq = lwork->lreq;
+
+	mutex_lock(&lreq->lock);
+	list_del(&lwork->pending_item);
+	mutex_unlock(&lreq->lock);
+
+	linger_put(lreq);
+	kfree(lwork);
+}
+
+static void lwork_queue(struct linger_work *lwork)
+{
+	struct ceph_osd_linger_request *lreq = lwork->lreq;
+	struct ceph_osd_client *osdc = lreq->osdc;
+
+	verify_lreq_locked(lreq);
+	WARN_ON(!list_empty(&lwork->pending_item));
+
+	lwork->queued_stamp = jiffies;
+	list_add_tail(&lwork->pending_item, &lreq->pending_lworks);
+	queue_work(osdc->notify_wq, &lwork->work);
+}
+
+static void do_watch_notify(struct work_struct *w)
+{
+	struct linger_work *lwork = container_of(w, struct linger_work, work);
+	struct ceph_osd_linger_request *lreq = lwork->lreq;
+
+	if (!linger_registered(lreq)) {
+		dout("%s lreq %p not registered\n", __func__, lreq);
+		goto out;
+	}
+
+	WARN_ON(!lreq->is_watch);
+	dout("%s lreq %p notify_id %llu notifier_id %llu payload_len %zu\n",
+	     __func__, lreq, lwork->notify.notify_id, lwork->notify.notifier_id,
+	     lwork->notify.payload_len);
+	lreq->wcb(lreq->data, lwork->notify.notify_id, lreq->linger_id,
+		  lwork->notify.notifier_id, lwork->notify.payload,
+		  lwork->notify.payload_len);
+
+out:
+	ceph_msg_put(lwork->notify.msg);
+	lwork_free(lwork);
+}
+
+static void do_watch_error(struct work_struct *w)
+{
+	struct linger_work *lwork = container_of(w, struct linger_work, work);
+	struct ceph_osd_linger_request *lreq = lwork->lreq;
+
+	if (!linger_registered(lreq)) {
+		dout("%s lreq %p not registered\n", __func__, lreq);
+		goto out;
+	}
+
+	dout("%s lreq %p err %d\n", __func__, lreq, lwork->error.err);
+	lreq->errcb(lreq->data, lreq->linger_id, lwork->error.err);
+
+out:
+	lwork_free(lwork);
+}
+
+static void queue_watch_error(struct ceph_osd_linger_request *lreq)
+{
+	struct linger_work *lwork;
+
+	lwork = lwork_alloc(lreq, do_watch_error);
+	if (!lwork) {
+		pr_err("failed to allocate error-lwork\n");
+		return;
+	}
+
+	lwork->error.err = lreq->last_error;
+	lwork_queue(lwork);
+}
+
+static void linger_reg_commit_complete(struct ceph_osd_linger_request *lreq,
+				       int result)
+{
+	if (!completion_done(&lreq->reg_commit_wait)) {
+		lreq->reg_commit_error = (result <= 0 ? result : 0);
+		complete_all(&lreq->reg_commit_wait);
+	}
+}
+
+static void linger_commit_cb(struct ceph_osd_request *req)
+{
+	struct ceph_osd_linger_request *lreq = req->r_priv;
+
+	mutex_lock(&lreq->lock);
+	if (req != lreq->reg_req) {
+		dout("%s lreq %p linger_id %llu unknown req (%p != %p)\n",
+		     __func__, lreq, lreq->linger_id, req, lreq->reg_req);
+		goto out;
+	}
+
+	dout("%s lreq %p linger_id %llu result %d\n", __func__, lreq,
+	     lreq->linger_id, req->r_result);
+	linger_reg_commit_complete(lreq, req->r_result);
+	lreq->committed = true;
+
+	if (!lreq->is_watch) {
+		struct ceph_osd_data *osd_data =
+		    osd_req_op_data(req, 0, notify, response_data);
+		void *p = page_address(osd_data->pages[0]);
+
+		WARN_ON(req->r_ops[0].op != CEPH_OSD_OP_NOTIFY ||
+			osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
+
+		/* make note of the notify_id */
+		if (req->r_ops[0].outdata_len >= sizeof(u64)) {
+			lreq->notify_id = ceph_decode_64(&p);
+			dout("lreq %p notify_id %llu\n", lreq,
+			     lreq->notify_id);
+		} else {
+			dout("lreq %p no notify_id\n", lreq);
+		}
+	}
+
+out:
+	mutex_unlock(&lreq->lock);
+	linger_put(lreq);
+}
+
+static int normalize_watch_error(int err)
+{
+	/*
+	 * Translate ENOENT -> ENOTCONN so that a delete->disconnection
+	 * notification and a failure to reconnect because we raced with
+	 * the delete appear the same to the user.
+	 */
+	if (err == -ENOENT)
+		err = -ENOTCONN;
+
+	return err;
+}
+
+static void linger_reconnect_cb(struct ceph_osd_request *req)
+{
+	struct ceph_osd_linger_request *lreq = req->r_priv;
+
+	mutex_lock(&lreq->lock);
+	if (req != lreq->reg_req) {
+		dout("%s lreq %p linger_id %llu unknown req (%p != %p)\n",
+		     __func__, lreq, lreq->linger_id, req, lreq->reg_req);
+		goto out;
+	}
+
+	dout("%s lreq %p linger_id %llu result %d last_error %d\n", __func__,
+	     lreq, lreq->linger_id, req->r_result, lreq->last_error);
+	if (req->r_result < 0) {
+		if (!lreq->last_error) {
+			lreq->last_error = normalize_watch_error(req->r_result);
+			queue_watch_error(lreq);
+		}
+	}
+
+out:
+	mutex_unlock(&lreq->lock);
+	linger_put(lreq);
+}
+
+static void send_linger(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+	struct ceph_osd_request *req;
+	int ret;
+
+	verify_osdc_wrlocked(osdc);
+	mutex_lock(&lreq->lock);
+	dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
+
+	if (lreq->reg_req) {
+		if (lreq->reg_req->r_osd)
+			cancel_linger_request(lreq->reg_req);
+		ceph_osdc_put_request(lreq->reg_req);
+	}
+
+	req = ceph_osdc_alloc_request(osdc, NULL, 1, true, GFP_NOIO);
+	BUG_ON(!req);
+
+	target_copy(&req->r_t, &lreq->t);
+	req->r_mtime = lreq->mtime;
+
+	if (lreq->is_watch && lreq->committed) {
+		osd_req_op_watch_init(req, 0, CEPH_OSD_WATCH_OP_RECONNECT,
+				      lreq->linger_id, ++lreq->register_gen);
+		dout("lreq %p reconnect register_gen %u\n", lreq,
+		     req->r_ops[0].watch.gen);
+		req->r_callback = linger_reconnect_cb;
+	} else {
+		if (lreq->is_watch) {
+			osd_req_op_watch_init(req, 0, CEPH_OSD_WATCH_OP_WATCH,
+					      lreq->linger_id, 0);
+		} else {
+			lreq->notify_id = 0;
+
+			refcount_inc(&lreq->request_pl->refcnt);
+			osd_req_op_notify_init(req, 0, lreq->linger_id,
+					       lreq->request_pl);
+			ceph_osd_data_pages_init(
+			    osd_req_op_data(req, 0, notify, response_data),
+			    lreq->notify_id_pages, PAGE_SIZE, 0, false, false);
+		}
+		dout("lreq %p register\n", lreq);
+		req->r_callback = linger_commit_cb;
+	}
+
+	ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
+	BUG_ON(ret);
+
+	req->r_priv = linger_get(lreq);
+	req->r_linger = true;
+	lreq->reg_req = req;
+	mutex_unlock(&lreq->lock);
+
+	submit_request(req, true);
+}
+
+static void linger_ping_cb(struct ceph_osd_request *req)
+{
+	struct ceph_osd_linger_request *lreq = req->r_priv;
+
+	mutex_lock(&lreq->lock);
+	if (req != lreq->ping_req) {
+		dout("%s lreq %p linger_id %llu unknown req (%p != %p)\n",
+		     __func__, lreq, lreq->linger_id, req, lreq->ping_req);
+		goto out;
+	}
+
+	dout("%s lreq %p linger_id %llu result %d ping_sent %lu last_error %d\n",
+	     __func__, lreq, lreq->linger_id, req->r_result, lreq->ping_sent,
+	     lreq->last_error);
+	if (lreq->register_gen == req->r_ops[0].watch.gen) {
+		if (!req->r_result) {
+			lreq->watch_valid_thru = lreq->ping_sent;
+		} else if (!lreq->last_error) {
+			lreq->last_error = normalize_watch_error(req->r_result);
+			queue_watch_error(lreq);
+		}
+	} else {
+		dout("lreq %p register_gen %u ignoring old pong %u\n", lreq,
+		     lreq->register_gen, req->r_ops[0].watch.gen);
+	}
+
+out:
+	mutex_unlock(&lreq->lock);
+	linger_put(lreq);
+}
+
+static void send_linger_ping(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+	struct ceph_osd_request *req;
+	int ret;
+
+	if (ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSERD)) {
+		dout("%s PAUSERD\n", __func__);
+		return;
+	}
+
+	lreq->ping_sent = jiffies;
+	dout("%s lreq %p linger_id %llu ping_sent %lu register_gen %u\n",
+	     __func__, lreq, lreq->linger_id, lreq->ping_sent,
+	     lreq->register_gen);
+
+	if (lreq->ping_req) {
+		if (lreq->ping_req->r_osd)
+			cancel_linger_request(lreq->ping_req);
+		ceph_osdc_put_request(lreq->ping_req);
+	}
+
+	req = ceph_osdc_alloc_request(osdc, NULL, 1, true, GFP_NOIO);
+	BUG_ON(!req);
+
+	target_copy(&req->r_t, &lreq->t);
+	osd_req_op_watch_init(req, 0, CEPH_OSD_WATCH_OP_PING, lreq->linger_id,
+			      lreq->register_gen);
+	req->r_callback = linger_ping_cb;
+
+	ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
+	BUG_ON(ret);
+
+	req->r_priv = linger_get(lreq);
+	req->r_linger = true;
+	lreq->ping_req = req;
+
+	ceph_osdc_get_request(req);
+	account_request(req);
+	req->r_tid = atomic64_inc_return(&osdc->last_tid);
+	link_request(lreq->osd, req);
+	send_request(req);
+}
+
+static void linger_submit(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+	struct ceph_osd *osd;
+
+	down_write(&osdc->lock);
+	linger_register(lreq);
+
+	calc_target(osdc, &lreq->t, false);
+	osd = lookup_create_osd(osdc, lreq->t.osd, true);
+	link_linger(osd, lreq);
+
+	send_linger(lreq);
+	up_write(&osdc->lock);
+}
+
+static void cancel_linger_map_check(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+	struct ceph_osd_linger_request *lookup_lreq;
+
+	verify_osdc_wrlocked(osdc);
+
+	lookup_lreq = lookup_linger_mc(&osdc->linger_map_checks,
+				       lreq->linger_id);
+	if (!lookup_lreq)
+		return;
+
+	WARN_ON(lookup_lreq != lreq);
+	erase_linger_mc(&osdc->linger_map_checks, lreq);
+	linger_put(lreq);
+}
+
+/*
+ * @lreq has to be both registered and linked.
+ */
+static void __linger_cancel(struct ceph_osd_linger_request *lreq)
+{
+	if (lreq->ping_req && lreq->ping_req->r_osd)
+		cancel_linger_request(lreq->ping_req);
+	if (lreq->reg_req && lreq->reg_req->r_osd)
+		cancel_linger_request(lreq->reg_req);
+	cancel_linger_map_check(lreq);
+	unlink_linger(lreq->osd, lreq);
+	linger_unregister(lreq);
+}
+
+static void linger_cancel(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+
+	down_write(&osdc->lock);
+	if (__linger_registered(lreq))
+		__linger_cancel(lreq);
+	up_write(&osdc->lock);
+}
+
+static void send_linger_map_check(struct ceph_osd_linger_request *lreq);
+
+static void check_linger_pool_dne(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+	struct ceph_osdmap *map = osdc->osdmap;
+
+	verify_osdc_wrlocked(osdc);
+	WARN_ON(!map->epoch);
+
+	if (lreq->register_gen) {
+		lreq->map_dne_bound = map->epoch;
+		dout("%s lreq %p linger_id %llu pool disappeared\n", __func__,
+		     lreq, lreq->linger_id);
+	} else {
+		dout("%s lreq %p linger_id %llu map_dne_bound %u have %u\n",
+		     __func__, lreq, lreq->linger_id, lreq->map_dne_bound,
+		     map->epoch);
+	}
+
+	if (lreq->map_dne_bound) {
+		if (map->epoch >= lreq->map_dne_bound) {
+			/* we had a new enough map */
+			pr_info("linger_id %llu pool does not exist\n",
+				lreq->linger_id);
+			linger_reg_commit_complete(lreq, -ENOENT);
+			__linger_cancel(lreq);
+		}
+	} else {
+		send_linger_map_check(lreq);
+	}
+}
+
+static void linger_map_check_cb(struct ceph_mon_generic_request *greq)
+{
+	struct ceph_osd_client *osdc = &greq->monc->client->osdc;
+	struct ceph_osd_linger_request *lreq;
+	u64 linger_id = greq->private_data;
+
+	WARN_ON(greq->result || !greq->u.newest);
+
+	down_write(&osdc->lock);
+	lreq = lookup_linger_mc(&osdc->linger_map_checks, linger_id);
+	if (!lreq) {
+		dout("%s linger_id %llu dne\n", __func__, linger_id);
+		goto out_unlock;
+	}
+
+	dout("%s lreq %p linger_id %llu map_dne_bound %u newest %llu\n",
+	     __func__, lreq, lreq->linger_id, lreq->map_dne_bound,
+	     greq->u.newest);
+	if (!lreq->map_dne_bound)
+		lreq->map_dne_bound = greq->u.newest;
+	erase_linger_mc(&osdc->linger_map_checks, lreq);
+	check_linger_pool_dne(lreq);
+
+	linger_put(lreq);
+out_unlock:
+	up_write(&osdc->lock);
+}
+
+static void send_linger_map_check(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+	struct ceph_osd_linger_request *lookup_lreq;
+	int ret;
+
+	verify_osdc_wrlocked(osdc);
+
+	lookup_lreq = lookup_linger_mc(&osdc->linger_map_checks,
+				       lreq->linger_id);
+	if (lookup_lreq) {
+		WARN_ON(lookup_lreq != lreq);
+		return;
+	}
+
+	linger_get(lreq);
+	insert_linger_mc(&osdc->linger_map_checks, lreq);
+	ret = ceph_monc_get_version_async(&osdc->client->monc, "osdmap",
+					  linger_map_check_cb, lreq->linger_id);
+	WARN_ON(ret);
+}
+
+static int linger_reg_commit_wait(struct ceph_osd_linger_request *lreq)
+{
+	int ret;
+
+	dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
+	ret = wait_for_completion_killable(&lreq->reg_commit_wait);
+	return ret ?: lreq->reg_commit_error;
+}
+
+static int linger_notify_finish_wait(struct ceph_osd_linger_request *lreq,
+				     unsigned long timeout)
+{
+	long left;
+
+	dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
+	left = wait_for_completion_killable_timeout(&lreq->notify_finish_wait,
+						ceph_timeout_jiffies(timeout));
+	if (left <= 0)
+		left = left ?: -ETIMEDOUT;
+	else
+		left = lreq->notify_finish_error; /* completed */
+
+	return left;
+}
+
+/*
+ * Timeout callback, called every N seconds.  When 1 or more OSD
+ * requests has been active for more than N seconds, we send a keepalive
+ * (tag + timestamp) to its OSD to ensure any communications channel
+ * reset is detected.
+ */
+static void handle_timeout(struct work_struct *work)
+{
+	struct ceph_osd_client *osdc =
+		container_of(work, struct ceph_osd_client, timeout_work.work);
+	struct ceph_options *opts = osdc->client->options;
+	unsigned long cutoff = jiffies - opts->osd_keepalive_timeout;
+	unsigned long expiry_cutoff = jiffies - opts->osd_request_timeout;
+	LIST_HEAD(slow_osds);
+	struct rb_node *n, *p;
+
+	dout("%s osdc %p\n", __func__, osdc);
+	down_write(&osdc->lock);
+
+	/*
+	 * ping osds that are a bit slow.  this ensures that if there
+	 * is a break in the TCP connection we will notice, and reopen
+	 * a connection with that osd (from the fault callback).
+	 */
+	for (n = rb_first(&osdc->osds); n; n = rb_next(n)) {
+		struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node);
+		bool found = false;
+
+		for (p = rb_first(&osd->o_requests); p; ) {
+			struct ceph_osd_request *req =
+			    rb_entry(p, struct ceph_osd_request, r_node);
+
+			p = rb_next(p); /* abort_request() */
+
+			if (time_before(req->r_stamp, cutoff)) {
+				dout(" req %p tid %llu on osd%d is laggy\n",
+				     req, req->r_tid, osd->o_osd);
+				found = true;
+			}
+			if (opts->osd_request_timeout &&
+			    time_before(req->r_start_stamp, expiry_cutoff)) {
+				pr_err_ratelimited("tid %llu on osd%d timeout\n",
+				       req->r_tid, osd->o_osd);
+				abort_request(req, -ETIMEDOUT);
+			}
+		}
+		for (p = rb_first(&osd->o_linger_requests); p; p = rb_next(p)) {
+			struct ceph_osd_linger_request *lreq =
+			    rb_entry(p, struct ceph_osd_linger_request, node);
+
+			dout(" lreq %p linger_id %llu is served by osd%d\n",
+			     lreq, lreq->linger_id, osd->o_osd);
+			found = true;
+
+			mutex_lock(&lreq->lock);
+			if (lreq->is_watch && lreq->committed && !lreq->last_error)
+				send_linger_ping(lreq);
+			mutex_unlock(&lreq->lock);
+		}
+
+		if (found)
+			list_move_tail(&osd->o_keepalive_item, &slow_osds);
+	}
+
+	if (opts->osd_request_timeout) {
+		for (p = rb_first(&osdc->homeless_osd.o_requests); p; ) {
+			struct ceph_osd_request *req =
+			    rb_entry(p, struct ceph_osd_request, r_node);
+
+			p = rb_next(p); /* abort_request() */
+
+			if (time_before(req->r_start_stamp, expiry_cutoff)) {
+				pr_err_ratelimited("tid %llu on osd%d timeout\n",
+				       req->r_tid, osdc->homeless_osd.o_osd);
+				abort_request(req, -ETIMEDOUT);
+			}
+		}
+	}
+
+	if (atomic_read(&osdc->num_homeless) || !list_empty(&slow_osds))
+		maybe_request_map(osdc);
+
+	while (!list_empty(&slow_osds)) {
+		struct ceph_osd *osd = list_first_entry(&slow_osds,
+							struct ceph_osd,
+							o_keepalive_item);
+		list_del_init(&osd->o_keepalive_item);
+		ceph_con_keepalive(&osd->o_con);
+	}
+
+	up_write(&osdc->lock);
+	schedule_delayed_work(&osdc->timeout_work,
+			      osdc->client->options->osd_keepalive_timeout);
+}
+
+static void handle_osds_timeout(struct work_struct *work)
+{
+	struct ceph_osd_client *osdc =
+		container_of(work, struct ceph_osd_client,
+			     osds_timeout_work.work);
+	unsigned long delay = osdc->client->options->osd_idle_ttl / 4;
+	struct ceph_osd *osd, *nosd;
+
+	dout("%s osdc %p\n", __func__, osdc);
+	down_write(&osdc->lock);
+	list_for_each_entry_safe(osd, nosd, &osdc->osd_lru, o_osd_lru) {
+		if (time_before(jiffies, osd->lru_ttl))
+			break;
+
+		WARN_ON(!RB_EMPTY_ROOT(&osd->o_requests));
+		WARN_ON(!RB_EMPTY_ROOT(&osd->o_linger_requests));
+		close_osd(osd);
+	}
+
+	up_write(&osdc->lock);
+	schedule_delayed_work(&osdc->osds_timeout_work,
+			      round_jiffies_relative(delay));
+}
+
+static int ceph_oloc_decode(void **p, void *end,
+			    struct ceph_object_locator *oloc)
+{
+	u8 struct_v, struct_cv;
+	u32 len;
+	void *struct_end;
+	int ret = 0;
+
+	ceph_decode_need(p, end, 1 + 1 + 4, e_inval);
+	struct_v = ceph_decode_8(p);
+	struct_cv = ceph_decode_8(p);
+	if (struct_v < 3) {
+		pr_warn("got v %d < 3 cv %d of ceph_object_locator\n",
+			struct_v, struct_cv);
+		goto e_inval;
+	}
+	if (struct_cv > 6) {
+		pr_warn("got v %d cv %d > 6 of ceph_object_locator\n",
+			struct_v, struct_cv);
+		goto e_inval;
+	}
+	len = ceph_decode_32(p);
+	ceph_decode_need(p, end, len, e_inval);
+	struct_end = *p + len;
+
+	oloc->pool = ceph_decode_64(p);
+	*p += 4; /* skip preferred */
+
+	len = ceph_decode_32(p);
+	if (len > 0) {
+		pr_warn("ceph_object_locator::key is set\n");
+		goto e_inval;
+	}
+
+	if (struct_v >= 5) {
+		bool changed = false;
+
+		len = ceph_decode_32(p);
+		if (len > 0) {
+			ceph_decode_need(p, end, len, e_inval);
+			if (!oloc->pool_ns ||
+			    ceph_compare_string(oloc->pool_ns, *p, len))
+				changed = true;
+			*p += len;
+		} else {
+			if (oloc->pool_ns)
+				changed = true;
+		}
+		if (changed) {
+			/* redirect changes namespace */
+			pr_warn("ceph_object_locator::nspace is changed\n");
+			goto e_inval;
+		}
+	}
+
+	if (struct_v >= 6) {
+		s64 hash = ceph_decode_64(p);
+		if (hash != -1) {
+			pr_warn("ceph_object_locator::hash is set\n");
+			goto e_inval;
+		}
+	}
+
+	/* skip the rest */
+	*p = struct_end;
+out:
+	return ret;
+
+e_inval:
+	ret = -EINVAL;
+	goto out;
+}
+
+static int ceph_redirect_decode(void **p, void *end,
+				struct ceph_request_redirect *redir)
+{
+	u8 struct_v, struct_cv;
+	u32 len;
+	void *struct_end;
+	int ret;
+
+	ceph_decode_need(p, end, 1 + 1 + 4, e_inval);
+	struct_v = ceph_decode_8(p);
+	struct_cv = ceph_decode_8(p);
+	if (struct_cv > 1) {
+		pr_warn("got v %d cv %d > 1 of ceph_request_redirect\n",
+			struct_v, struct_cv);
+		goto e_inval;
+	}
+	len = ceph_decode_32(p);
+	ceph_decode_need(p, end, len, e_inval);
+	struct_end = *p + len;
+
+	ret = ceph_oloc_decode(p, end, &redir->oloc);
+	if (ret)
+		goto out;
+
+	len = ceph_decode_32(p);
+	if (len > 0) {
+		pr_warn("ceph_request_redirect::object_name is set\n");
+		goto e_inval;
+	}
+
+	/* skip the rest */
+	*p = struct_end;
+out:
+	return ret;
+
+e_inval:
+	ret = -EINVAL;
+	goto out;
+}
+
+struct MOSDOpReply {
+	struct ceph_pg pgid;
+	u64 flags;
+	int result;
+	u32 epoch;
+	int num_ops;
+	u32 outdata_len[CEPH_OSD_MAX_OPS];
+	s32 rval[CEPH_OSD_MAX_OPS];
+	int retry_attempt;
+	struct ceph_eversion replay_version;
+	u64 user_version;
+	struct ceph_request_redirect redirect;
+};
+
+static int decode_MOSDOpReply(const struct ceph_msg *msg, struct MOSDOpReply *m)
+{
+	void *p = msg->front.iov_base;
+	void *const end = p + msg->front.iov_len;
+	u16 version = le16_to_cpu(msg->hdr.version);
+	struct ceph_eversion bad_replay_version;
+	u8 decode_redir;
+	u32 len;
+	int ret;
+	int i;
+
+	ceph_decode_32_safe(&p, end, len, e_inval);
+	ceph_decode_need(&p, end, len, e_inval);
+	p += len; /* skip oid */
+
+	ret = ceph_decode_pgid(&p, end, &m->pgid);
+	if (ret)
+		return ret;
+
+	ceph_decode_64_safe(&p, end, m->flags, e_inval);
+	ceph_decode_32_safe(&p, end, m->result, e_inval);
+	ceph_decode_need(&p, end, sizeof(bad_replay_version), e_inval);
+	memcpy(&bad_replay_version, p, sizeof(bad_replay_version));
+	p += sizeof(bad_replay_version);
+	ceph_decode_32_safe(&p, end, m->epoch, e_inval);
+
+	ceph_decode_32_safe(&p, end, m->num_ops, e_inval);
+	if (m->num_ops > ARRAY_SIZE(m->outdata_len))
+		goto e_inval;
+
+	ceph_decode_need(&p, end, m->num_ops * sizeof(struct ceph_osd_op),
+			 e_inval);
+	for (i = 0; i < m->num_ops; i++) {
+		struct ceph_osd_op *op = p;
+
+		m->outdata_len[i] = le32_to_cpu(op->payload_len);
+		p += sizeof(*op);
+	}
+
+	ceph_decode_32_safe(&p, end, m->retry_attempt, e_inval);
+	for (i = 0; i < m->num_ops; i++)
+		ceph_decode_32_safe(&p, end, m->rval[i], e_inval);
+
+	if (version >= 5) {
+		ceph_decode_need(&p, end, sizeof(m->replay_version), e_inval);
+		memcpy(&m->replay_version, p, sizeof(m->replay_version));
+		p += sizeof(m->replay_version);
+		ceph_decode_64_safe(&p, end, m->user_version, e_inval);
+	} else {
+		m->replay_version = bad_replay_version; /* struct */
+		m->user_version = le64_to_cpu(m->replay_version.version);
+	}
+
+	if (version >= 6) {
+		if (version >= 7)
+			ceph_decode_8_safe(&p, end, decode_redir, e_inval);
+		else
+			decode_redir = 1;
+	} else {
+		decode_redir = 0;
+	}
+
+	if (decode_redir) {
+		ret = ceph_redirect_decode(&p, end, &m->redirect);
+		if (ret)
+			return ret;
+	} else {
+		ceph_oloc_init(&m->redirect.oloc);
+	}
+
+	return 0;
+
+e_inval:
+	return -EINVAL;
+}
+
+/*
+ * Handle MOSDOpReply.  Set ->r_result and call the callback if it is
+ * specified.
+ */
+static void handle_reply(struct ceph_osd *osd, struct ceph_msg *msg)
+{
+	struct ceph_osd_client *osdc = osd->o_osdc;
+	struct ceph_osd_request *req;
+	struct MOSDOpReply m;
+	u64 tid = le64_to_cpu(msg->hdr.tid);
+	u32 data_len = 0;
+	int ret;
+	int i;
+
+	dout("%s msg %p tid %llu\n", __func__, msg, tid);
+
+	down_read(&osdc->lock);
+	if (!osd_registered(osd)) {
+		dout("%s osd%d unknown\n", __func__, osd->o_osd);
+		goto out_unlock_osdc;
+	}
+	WARN_ON(osd->o_osd != le64_to_cpu(msg->hdr.src.num));
+
+	mutex_lock(&osd->lock);
+	req = lookup_request(&osd->o_requests, tid);
+	if (!req) {
+		dout("%s osd%d tid %llu unknown\n", __func__, osd->o_osd, tid);
+		goto out_unlock_session;
+	}
+
+	m.redirect.oloc.pool_ns = req->r_t.target_oloc.pool_ns;
+	ret = decode_MOSDOpReply(msg, &m);
+	m.redirect.oloc.pool_ns = NULL;
+	if (ret) {
+		pr_err("failed to decode MOSDOpReply for tid %llu: %d\n",
+		       req->r_tid, ret);
+		ceph_msg_dump(msg);
+		goto fail_request;
+	}
+	dout("%s req %p tid %llu flags 0x%llx pgid %llu.%x epoch %u attempt %d v %u'%llu uv %llu\n",
+	     __func__, req, req->r_tid, m.flags, m.pgid.pool, m.pgid.seed,
+	     m.epoch, m.retry_attempt, le32_to_cpu(m.replay_version.epoch),
+	     le64_to_cpu(m.replay_version.version), m.user_version);
+
+	if (m.retry_attempt >= 0) {
+		if (m.retry_attempt != req->r_attempts - 1) {
+			dout("req %p tid %llu retry_attempt %d != %d, ignoring\n",
+			     req, req->r_tid, m.retry_attempt,
+			     req->r_attempts - 1);
+			goto out_unlock_session;
+		}
+	} else {
+		WARN_ON(1); /* MOSDOpReply v4 is assumed */
+	}
+
+	if (!ceph_oloc_empty(&m.redirect.oloc)) {
+		dout("req %p tid %llu redirect pool %lld\n", req, req->r_tid,
+		     m.redirect.oloc.pool);
+		unlink_request(osd, req);
+		mutex_unlock(&osd->lock);
+
+		/*
+		 * Not ceph_oloc_copy() - changing pool_ns is not
+		 * supported.
+		 */
+		req->r_t.target_oloc.pool = m.redirect.oloc.pool;
+		req->r_flags |= CEPH_OSD_FLAG_REDIRECTED |
+				CEPH_OSD_FLAG_IGNORE_OVERLAY |
+				CEPH_OSD_FLAG_IGNORE_CACHE;
+		req->r_tid = 0;
+		__submit_request(req, false);
+		goto out_unlock_osdc;
+	}
+
+	if (m.result == -EAGAIN) {
+		dout("req %p tid %llu EAGAIN\n", req, req->r_tid);
+		unlink_request(osd, req);
+		mutex_unlock(&osd->lock);
+
+		/*
+		 * The object is missing on the replica or not (yet)
+		 * readable.  Clear pgid to force a resend to the primary
+		 * via legacy_change.
+		 */
+		req->r_t.pgid.pool = 0;
+		req->r_t.pgid.seed = 0;
+		WARN_ON(!req->r_t.used_replica);
+		req->r_flags &= ~(CEPH_OSD_FLAG_BALANCE_READS |
+				  CEPH_OSD_FLAG_LOCALIZE_READS);
+		req->r_tid = 0;
+		__submit_request(req, false);
+		goto out_unlock_osdc;
+	}
+
+	if (m.num_ops != req->r_num_ops) {
+		pr_err("num_ops %d != %d for tid %llu\n", m.num_ops,
+		       req->r_num_ops, req->r_tid);
+		goto fail_request;
+	}
+	for (i = 0; i < req->r_num_ops; i++) {
+		dout(" req %p tid %llu op %d rval %d len %u\n", req,
+		     req->r_tid, i, m.rval[i], m.outdata_len[i]);
+		req->r_ops[i].rval = m.rval[i];
+		req->r_ops[i].outdata_len = m.outdata_len[i];
+		data_len += m.outdata_len[i];
+	}
+	if (data_len != le32_to_cpu(msg->hdr.data_len)) {
+		pr_err("sum of lens %u != %u for tid %llu\n", data_len,
+		       le32_to_cpu(msg->hdr.data_len), req->r_tid);
+		goto fail_request;
+	}
+	dout("%s req %p tid %llu result %d data_len %u\n", __func__,
+	     req, req->r_tid, m.result, data_len);
+
+	/*
+	 * Since we only ever request ONDISK, we should only ever get
+	 * one (type of) reply back.
+	 */
+	WARN_ON(!(m.flags & CEPH_OSD_FLAG_ONDISK));
+	req->r_result = m.result ?: data_len;
+	finish_request(req);
+	mutex_unlock(&osd->lock);
+	up_read(&osdc->lock);
+
+	__complete_request(req);
+	return;
+
+fail_request:
+	complete_request(req, -EIO);
+out_unlock_session:
+	mutex_unlock(&osd->lock);
+out_unlock_osdc:
+	up_read(&osdc->lock);
+}
+
+static void set_pool_was_full(struct ceph_osd_client *osdc)
+{
+	struct rb_node *n;
+
+	for (n = rb_first(&osdc->osdmap->pg_pools); n; n = rb_next(n)) {
+		struct ceph_pg_pool_info *pi =
+		    rb_entry(n, struct ceph_pg_pool_info, node);
+
+		pi->was_full = __pool_full(pi);
+	}
+}
+
+static bool pool_cleared_full(struct ceph_osd_client *osdc, s64 pool_id)
+{
+	struct ceph_pg_pool_info *pi;
+
+	pi = ceph_pg_pool_by_id(osdc->osdmap, pool_id);
+	if (!pi)
+		return false;
+
+	return pi->was_full && !__pool_full(pi);
+}
+
+static enum calc_target_result
+recalc_linger_target(struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_osd_client *osdc = lreq->osdc;
+	enum calc_target_result ct_res;
+
+	ct_res = calc_target(osdc, &lreq->t, true);
+	if (ct_res == CALC_TARGET_NEED_RESEND) {
+		struct ceph_osd *osd;
+
+		osd = lookup_create_osd(osdc, lreq->t.osd, true);
+		if (osd != lreq->osd) {
+			unlink_linger(lreq->osd, lreq);
+			link_linger(osd, lreq);
+		}
+	}
+
+	return ct_res;
+}
+
+/*
+ * Requeue requests whose mapping to an OSD has changed.
+ */
+static void scan_requests(struct ceph_osd *osd,
+			  bool force_resend,
+			  bool cleared_full,
+			  bool check_pool_cleared_full,
+			  struct rb_root *need_resend,
+			  struct list_head *need_resend_linger)
+{
+	struct ceph_osd_client *osdc = osd->o_osdc;
+	struct rb_node *n;
+	bool force_resend_writes;
+
+	for (n = rb_first(&osd->o_linger_requests); n; ) {
+		struct ceph_osd_linger_request *lreq =
+		    rb_entry(n, struct ceph_osd_linger_request, node);
+		enum calc_target_result ct_res;
+
+		n = rb_next(n); /* recalc_linger_target() */
+
+		dout("%s lreq %p linger_id %llu\n", __func__, lreq,
+		     lreq->linger_id);
+		ct_res = recalc_linger_target(lreq);
+		switch (ct_res) {
+		case CALC_TARGET_NO_ACTION:
+			force_resend_writes = cleared_full ||
+			    (check_pool_cleared_full &&
+			     pool_cleared_full(osdc, lreq->t.base_oloc.pool));
+			if (!force_resend && !force_resend_writes)
+				break;
+
+			fallthrough;
+		case CALC_TARGET_NEED_RESEND:
+			cancel_linger_map_check(lreq);
+			/*
+			 * scan_requests() for the previous epoch(s)
+			 * may have already added it to the list, since
+			 * it's not unlinked here.
+			 */
+			if (list_empty(&lreq->scan_item))
+				list_add_tail(&lreq->scan_item, need_resend_linger);
+			break;
+		case CALC_TARGET_POOL_DNE:
+			list_del_init(&lreq->scan_item);
+			check_linger_pool_dne(lreq);
+			break;
+		}
+	}
+
+	for (n = rb_first(&osd->o_requests); n; ) {
+		struct ceph_osd_request *req =
+		    rb_entry(n, struct ceph_osd_request, r_node);
+		enum calc_target_result ct_res;
+
+		n = rb_next(n); /* unlink_request(), check_pool_dne() */
+
+		dout("%s req %p tid %llu\n", __func__, req, req->r_tid);
+		ct_res = calc_target(osdc, &req->r_t, false);
+		switch (ct_res) {
+		case CALC_TARGET_NO_ACTION:
+			force_resend_writes = cleared_full ||
+			    (check_pool_cleared_full &&
+			     pool_cleared_full(osdc, req->r_t.base_oloc.pool));
+			if (!force_resend &&
+			    (!(req->r_flags & CEPH_OSD_FLAG_WRITE) ||
+			     !force_resend_writes))
+				break;
+
+			fallthrough;
+		case CALC_TARGET_NEED_RESEND:
+			cancel_map_check(req);
+			unlink_request(osd, req);
+			insert_request(need_resend, req);
+			break;
+		case CALC_TARGET_POOL_DNE:
+			check_pool_dne(req);
+			break;
+		}
+	}
+}
+
+static int handle_one_map(struct ceph_osd_client *osdc,
+			  void *p, void *end, bool incremental,
+			  struct rb_root *need_resend,
+			  struct list_head *need_resend_linger)
+{
+	struct ceph_osdmap *newmap;
+	struct rb_node *n;
+	bool skipped_map = false;
+	bool was_full;
+
+	was_full = ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL);
+	set_pool_was_full(osdc);
+
+	if (incremental)
+		newmap = osdmap_apply_incremental(&p, end, osdc->osdmap);
+	else
+		newmap = ceph_osdmap_decode(&p, end);
+	if (IS_ERR(newmap))
+		return PTR_ERR(newmap);
+
+	if (newmap != osdc->osdmap) {
+		/*
+		 * Preserve ->was_full before destroying the old map.
+		 * For pools that weren't in the old map, ->was_full
+		 * should be false.
+		 */
+		for (n = rb_first(&newmap->pg_pools); n; n = rb_next(n)) {
+			struct ceph_pg_pool_info *pi =
+			    rb_entry(n, struct ceph_pg_pool_info, node);
+			struct ceph_pg_pool_info *old_pi;
+
+			old_pi = ceph_pg_pool_by_id(osdc->osdmap, pi->id);
+			if (old_pi)
+				pi->was_full = old_pi->was_full;
+			else
+				WARN_ON(pi->was_full);
+		}
+
+		if (osdc->osdmap->epoch &&
+		    osdc->osdmap->epoch + 1 < newmap->epoch) {
+			WARN_ON(incremental);
+			skipped_map = true;
+		}
+
+		ceph_osdmap_destroy(osdc->osdmap);
+		osdc->osdmap = newmap;
+	}
+
+	was_full &= !ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL);
+	scan_requests(&osdc->homeless_osd, skipped_map, was_full, true,
+		      need_resend, need_resend_linger);
+
+	for (n = rb_first(&osdc->osds); n; ) {
+		struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node);
+
+		n = rb_next(n); /* close_osd() */
+
+		scan_requests(osd, skipped_map, was_full, true, need_resend,
+			      need_resend_linger);
+		if (!ceph_osd_is_up(osdc->osdmap, osd->o_osd) ||
+		    memcmp(&osd->o_con.peer_addr,
+			   ceph_osd_addr(osdc->osdmap, osd->o_osd),
+			   sizeof(struct ceph_entity_addr)))
+			close_osd(osd);
+	}
+
+	return 0;
+}
+
+static void kick_requests(struct ceph_osd_client *osdc,
+			  struct rb_root *need_resend,
+			  struct list_head *need_resend_linger)
+{
+	struct ceph_osd_linger_request *lreq, *nlreq;
+	enum calc_target_result ct_res;
+	struct rb_node *n;
+
+	/* make sure need_resend targets reflect latest map */
+	for (n = rb_first(need_resend); n; ) {
+		struct ceph_osd_request *req =
+		    rb_entry(n, struct ceph_osd_request, r_node);
+
+		n = rb_next(n);
+
+		if (req->r_t.epoch < osdc->osdmap->epoch) {
+			ct_res = calc_target(osdc, &req->r_t, false);
+			if (ct_res == CALC_TARGET_POOL_DNE) {
+				erase_request(need_resend, req);
+				check_pool_dne(req);
+			}
+		}
+	}
+
+	for (n = rb_first(need_resend); n; ) {
+		struct ceph_osd_request *req =
+		    rb_entry(n, struct ceph_osd_request, r_node);
+		struct ceph_osd *osd;
+
+		n = rb_next(n);
+		erase_request(need_resend, req); /* before link_request() */
+
+		osd = lookup_create_osd(osdc, req->r_t.osd, true);
+		link_request(osd, req);
+		if (!req->r_linger) {
+			if (!osd_homeless(osd) && !req->r_t.paused)
+				send_request(req);
+		} else {
+			cancel_linger_request(req);
+		}
+	}
+
+	list_for_each_entry_safe(lreq, nlreq, need_resend_linger, scan_item) {
+		if (!osd_homeless(lreq->osd))
+			send_linger(lreq);
+
+		list_del_init(&lreq->scan_item);
+	}
+}
+
+/*
+ * Process updated osd map.
+ *
+ * The message contains any number of incremental and full maps, normally
+ * indicating some sort of topology change in the cluster.  Kick requests
+ * off to different OSDs as needed.
+ */
+void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg)
+{
+	void *p = msg->front.iov_base;
+	void *const end = p + msg->front.iov_len;
+	u32 nr_maps, maplen;
+	u32 epoch;
+	struct ceph_fsid fsid;
+	struct rb_root need_resend = RB_ROOT;
+	LIST_HEAD(need_resend_linger);
+	bool handled_incremental = false;
+	bool was_pauserd, was_pausewr;
+	bool pauserd, pausewr;
+	int err;
+
+	dout("%s have %u\n", __func__, osdc->osdmap->epoch);
+	down_write(&osdc->lock);
+
+	/* verify fsid */
+	ceph_decode_need(&p, end, sizeof(fsid), bad);
+	ceph_decode_copy(&p, &fsid, sizeof(fsid));
+	if (ceph_check_fsid(osdc->client, &fsid) < 0)
+		goto bad;
+
+	was_pauserd = ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSERD);
+	was_pausewr = ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSEWR) ||
+		      ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) ||
+		      have_pool_full(osdc);
+
+	/* incremental maps */
+	ceph_decode_32_safe(&p, end, nr_maps, bad);
+	dout(" %d inc maps\n", nr_maps);
+	while (nr_maps > 0) {
+		ceph_decode_need(&p, end, 2*sizeof(u32), bad);
+		epoch = ceph_decode_32(&p);
+		maplen = ceph_decode_32(&p);
+		ceph_decode_need(&p, end, maplen, bad);
+		if (osdc->osdmap->epoch &&
+		    osdc->osdmap->epoch + 1 == epoch) {
+			dout("applying incremental map %u len %d\n",
+			     epoch, maplen);
+			err = handle_one_map(osdc, p, p + maplen, true,
+					     &need_resend, &need_resend_linger);
+			if (err)
+				goto bad;
+			handled_incremental = true;
+		} else {
+			dout("ignoring incremental map %u len %d\n",
+			     epoch, maplen);
+		}
+		p += maplen;
+		nr_maps--;
+	}
+	if (handled_incremental)
+		goto done;
+
+	/* full maps */
+	ceph_decode_32_safe(&p, end, nr_maps, bad);
+	dout(" %d full maps\n", nr_maps);
+	while (nr_maps) {
+		ceph_decode_need(&p, end, 2*sizeof(u32), bad);
+		epoch = ceph_decode_32(&p);
+		maplen = ceph_decode_32(&p);
+		ceph_decode_need(&p, end, maplen, bad);
+		if (nr_maps > 1) {
+			dout("skipping non-latest full map %u len %d\n",
+			     epoch, maplen);
+		} else if (osdc->osdmap->epoch >= epoch) {
+			dout("skipping full map %u len %d, "
+			     "older than our %u\n", epoch, maplen,
+			     osdc->osdmap->epoch);
+		} else {
+			dout("taking full map %u len %d\n", epoch, maplen);
+			err = handle_one_map(osdc, p, p + maplen, false,
+					     &need_resend, &need_resend_linger);
+			if (err)
+				goto bad;
+		}
+		p += maplen;
+		nr_maps--;
+	}
+
+done:
+	/*
+	 * subscribe to subsequent osdmap updates if full to ensure
+	 * we find out when we are no longer full and stop returning
+	 * ENOSPC.
+	 */
+	pauserd = ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSERD);
+	pausewr = ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSEWR) ||
+		  ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) ||
+		  have_pool_full(osdc);
+	if (was_pauserd || was_pausewr || pauserd || pausewr ||
+	    osdc->osdmap->epoch < osdc->epoch_barrier)
+		maybe_request_map(osdc);
+
+	kick_requests(osdc, &need_resend, &need_resend_linger);
+
+	ceph_osdc_abort_on_full(osdc);
+	ceph_monc_got_map(&osdc->client->monc, CEPH_SUB_OSDMAP,
+			  osdc->osdmap->epoch);
+	up_write(&osdc->lock);
+	wake_up_all(&osdc->client->auth_wq);
+	return;
+
+bad:
+	pr_err("osdc handle_map corrupt msg\n");
+	ceph_msg_dump(msg);
+	up_write(&osdc->lock);
+}
+
+/*
+ * Resubmit requests pending on the given osd.
+ */
+static void kick_osd_requests(struct ceph_osd *osd)
+{
+	struct rb_node *n;
+
+	clear_backoffs(osd);
+
+	for (n = rb_first(&osd->o_requests); n; ) {
+		struct ceph_osd_request *req =
+		    rb_entry(n, struct ceph_osd_request, r_node);
+
+		n = rb_next(n); /* cancel_linger_request() */
+
+		if (!req->r_linger) {
+			if (!req->r_t.paused)
+				send_request(req);
+		} else {
+			cancel_linger_request(req);
+		}
+	}
+	for (n = rb_first(&osd->o_linger_requests); n; n = rb_next(n)) {
+		struct ceph_osd_linger_request *lreq =
+		    rb_entry(n, struct ceph_osd_linger_request, node);
+
+		send_linger(lreq);
+	}
+}
+
+/*
+ * If the osd connection drops, we need to resubmit all requests.
+ */
+static void osd_fault(struct ceph_connection *con)
+{
+	struct ceph_osd *osd = con->private;
+	struct ceph_osd_client *osdc = osd->o_osdc;
+
+	dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);
+
+	down_write(&osdc->lock);
+	if (!osd_registered(osd)) {
+		dout("%s osd%d unknown\n", __func__, osd->o_osd);
+		goto out_unlock;
+	}
+
+	if (!reopen_osd(osd))
+		kick_osd_requests(osd);
+	maybe_request_map(osdc);
+
+out_unlock:
+	up_write(&osdc->lock);
+}
+
+struct MOSDBackoff {
+	struct ceph_spg spgid;
+	u32 map_epoch;
+	u8 op;
+	u64 id;
+	struct ceph_hobject_id *begin;
+	struct ceph_hobject_id *end;
+};
+
+static int decode_MOSDBackoff(const struct ceph_msg *msg, struct MOSDBackoff *m)
+{
+	void *p = msg->front.iov_base;
+	void *const end = p + msg->front.iov_len;
+	u8 struct_v;
+	u32 struct_len;
+	int ret;
+
+	ret = ceph_start_decoding(&p, end, 1, "spg_t", &struct_v, &struct_len);
+	if (ret)
+		return ret;
+
+	ret = ceph_decode_pgid(&p, end, &m->spgid.pgid);
+	if (ret)
+		return ret;
+
+	ceph_decode_8_safe(&p, end, m->spgid.shard, e_inval);
+	ceph_decode_32_safe(&p, end, m->map_epoch, e_inval);
+	ceph_decode_8_safe(&p, end, m->op, e_inval);
+	ceph_decode_64_safe(&p, end, m->id, e_inval);
+
+	m->begin = kzalloc(sizeof(*m->begin), GFP_NOIO);
+	if (!m->begin)
+		return -ENOMEM;
+
+	ret = decode_hoid(&p, end, m->begin);
+	if (ret) {
+		free_hoid(m->begin);
+		return ret;
+	}
+
+	m->end = kzalloc(sizeof(*m->end), GFP_NOIO);
+	if (!m->end) {
+		free_hoid(m->begin);
+		return -ENOMEM;
+	}
+
+	ret = decode_hoid(&p, end, m->end);
+	if (ret) {
+		free_hoid(m->begin);
+		free_hoid(m->end);
+		return ret;
+	}
+
+	return 0;
+
+e_inval:
+	return -EINVAL;
+}
+
+static struct ceph_msg *create_backoff_message(
+				const struct ceph_osd_backoff *backoff,
+				u32 map_epoch)
+{
+	struct ceph_msg *msg;
+	void *p, *end;
+	int msg_size;
+
+	msg_size = CEPH_ENCODING_START_BLK_LEN +
+			CEPH_PGID_ENCODING_LEN + 1; /* spgid */
+	msg_size += 4 + 1 + 8; /* map_epoch, op, id */
+	msg_size += CEPH_ENCODING_START_BLK_LEN +
+			hoid_encoding_size(backoff->begin);
+	msg_size += CEPH_ENCODING_START_BLK_LEN +
+			hoid_encoding_size(backoff->end);
+
+	msg = ceph_msg_new(CEPH_MSG_OSD_BACKOFF, msg_size, GFP_NOIO, true);
+	if (!msg)
+		return NULL;
+
+	p = msg->front.iov_base;
+	end = p + msg->front_alloc_len;
+
+	encode_spgid(&p, &backoff->spgid);
+	ceph_encode_32(&p, map_epoch);
+	ceph_encode_8(&p, CEPH_OSD_BACKOFF_OP_ACK_BLOCK);
+	ceph_encode_64(&p, backoff->id);
+	encode_hoid(&p, end, backoff->begin);
+	encode_hoid(&p, end, backoff->end);
+	BUG_ON(p != end);
+
+	msg->front.iov_len = p - msg->front.iov_base;
+	msg->hdr.version = cpu_to_le16(1); /* MOSDBackoff v1 */
+	msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
+
+	return msg;
+}
+
+static void handle_backoff_block(struct ceph_osd *osd, struct MOSDBackoff *m)
+{
+	struct ceph_spg_mapping *spg;
+	struct ceph_osd_backoff *backoff;
+	struct ceph_msg *msg;
+
+	dout("%s osd%d spgid %llu.%xs%d id %llu\n", __func__, osd->o_osd,
+	     m->spgid.pgid.pool, m->spgid.pgid.seed, m->spgid.shard, m->id);
+
+	spg = lookup_spg_mapping(&osd->o_backoff_mappings, &m->spgid);
+	if (!spg) {
+		spg = alloc_spg_mapping();
+		if (!spg) {
+			pr_err("%s failed to allocate spg\n", __func__);
+			return;
+		}
+		spg->spgid = m->spgid; /* struct */
+		insert_spg_mapping(&osd->o_backoff_mappings, spg);
+	}
+
+	backoff = alloc_backoff();
+	if (!backoff) {
+		pr_err("%s failed to allocate backoff\n", __func__);
+		return;
+	}
+	backoff->spgid = m->spgid; /* struct */
+	backoff->id = m->id;
+	backoff->begin = m->begin;
+	m->begin = NULL; /* backoff now owns this */
+	backoff->end = m->end;
+	m->end = NULL;   /* ditto */
+
+	insert_backoff(&spg->backoffs, backoff);
+	insert_backoff_by_id(&osd->o_backoffs_by_id, backoff);
+
+	/*
+	 * Ack with original backoff's epoch so that the OSD can
+	 * discard this if there was a PG split.
+	 */
+	msg = create_backoff_message(backoff, m->map_epoch);
+	if (!msg) {
+		pr_err("%s failed to allocate msg\n", __func__);
+		return;
+	}
+	ceph_con_send(&osd->o_con, msg);
+}
+
+static bool target_contained_by(const struct ceph_osd_request_target *t,
+				const struct ceph_hobject_id *begin,
+				const struct ceph_hobject_id *end)
+{
+	struct ceph_hobject_id hoid;
+	int cmp;
+
+	hoid_fill_from_target(&hoid, t);
+	cmp = hoid_compare(&hoid, begin);
+	return !cmp || (cmp > 0 && hoid_compare(&hoid, end) < 0);
+}
+
+static void handle_backoff_unblock(struct ceph_osd *osd,
+				   const struct MOSDBackoff *m)
+{
+	struct ceph_spg_mapping *spg;
+	struct ceph_osd_backoff *backoff;
+	struct rb_node *n;
+
+	dout("%s osd%d spgid %llu.%xs%d id %llu\n", __func__, osd->o_osd,
+	     m->spgid.pgid.pool, m->spgid.pgid.seed, m->spgid.shard, m->id);
+
+	backoff = lookup_backoff_by_id(&osd->o_backoffs_by_id, m->id);
+	if (!backoff) {
+		pr_err("%s osd%d spgid %llu.%xs%d id %llu backoff dne\n",
+		       __func__, osd->o_osd, m->spgid.pgid.pool,
+		       m->spgid.pgid.seed, m->spgid.shard, m->id);
+		return;
+	}
+
+	if (hoid_compare(backoff->begin, m->begin) &&
+	    hoid_compare(backoff->end, m->end)) {
+		pr_err("%s osd%d spgid %llu.%xs%d id %llu bad range?\n",
+		       __func__, osd->o_osd, m->spgid.pgid.pool,
+		       m->spgid.pgid.seed, m->spgid.shard, m->id);
+		/* unblock it anyway... */
+	}
+
+	spg = lookup_spg_mapping(&osd->o_backoff_mappings, &backoff->spgid);
+	BUG_ON(!spg);
+
+	erase_backoff(&spg->backoffs, backoff);
+	erase_backoff_by_id(&osd->o_backoffs_by_id, backoff);
+	free_backoff(backoff);
+
+	if (RB_EMPTY_ROOT(&spg->backoffs)) {
+		erase_spg_mapping(&osd->o_backoff_mappings, spg);
+		free_spg_mapping(spg);
+	}
+
+	for (n = rb_first(&osd->o_requests); n; n = rb_next(n)) {
+		struct ceph_osd_request *req =
+		    rb_entry(n, struct ceph_osd_request, r_node);
+
+		if (!ceph_spg_compare(&req->r_t.spgid, &m->spgid)) {
+			/*
+			 * Match against @m, not @backoff -- the PG may
+			 * have split on the OSD.
+			 */
+			if (target_contained_by(&req->r_t, m->begin, m->end)) {
+				/*
+				 * If no other installed backoff applies,
+				 * resend.
+				 */
+				send_request(req);
+			}
+		}
+	}
+}
+
+static void handle_backoff(struct ceph_osd *osd, struct ceph_msg *msg)
+{
+	struct ceph_osd_client *osdc = osd->o_osdc;
+	struct MOSDBackoff m;
+	int ret;
+
+	down_read(&osdc->lock);
+	if (!osd_registered(osd)) {
+		dout("%s osd%d unknown\n", __func__, osd->o_osd);
+		up_read(&osdc->lock);
+		return;
+	}
+	WARN_ON(osd->o_osd != le64_to_cpu(msg->hdr.src.num));
+
+	mutex_lock(&osd->lock);
+	ret = decode_MOSDBackoff(msg, &m);
+	if (ret) {
+		pr_err("failed to decode MOSDBackoff: %d\n", ret);
+		ceph_msg_dump(msg);
+		goto out_unlock;
+	}
+
+	switch (m.op) {
+	case CEPH_OSD_BACKOFF_OP_BLOCK:
+		handle_backoff_block(osd, &m);
+		break;
+	case CEPH_OSD_BACKOFF_OP_UNBLOCK:
+		handle_backoff_unblock(osd, &m);
+		break;
+	default:
+		pr_err("%s osd%d unknown op %d\n", __func__, osd->o_osd, m.op);
+	}
+
+	free_hoid(m.begin);
+	free_hoid(m.end);
+
+out_unlock:
+	mutex_unlock(&osd->lock);
+	up_read(&osdc->lock);
+}
+
+/*
+ * Process osd watch notifications
+ */
+static void handle_watch_notify(struct ceph_osd_client *osdc,
+				struct ceph_msg *msg)
+{
+	void *p = msg->front.iov_base;
+	void *const end = p + msg->front.iov_len;
+	struct ceph_osd_linger_request *lreq;
+	struct linger_work *lwork;
+	u8 proto_ver, opcode;
+	u64 cookie, notify_id;
+	u64 notifier_id = 0;
+	s32 return_code = 0;
+	void *payload = NULL;
+	u32 payload_len = 0;
+
+	ceph_decode_8_safe(&p, end, proto_ver, bad);
+	ceph_decode_8_safe(&p, end, opcode, bad);
+	ceph_decode_64_safe(&p, end, cookie, bad);
+	p += 8; /* skip ver */
+	ceph_decode_64_safe(&p, end, notify_id, bad);
+
+	if (proto_ver >= 1) {
+		ceph_decode_32_safe(&p, end, payload_len, bad);
+		ceph_decode_need(&p, end, payload_len, bad);
+		payload = p;
+		p += payload_len;
+	}
+
+	if (le16_to_cpu(msg->hdr.version) >= 2)
+		ceph_decode_32_safe(&p, end, return_code, bad);
+
+	if (le16_to_cpu(msg->hdr.version) >= 3)
+		ceph_decode_64_safe(&p, end, notifier_id, bad);
+
+	down_read(&osdc->lock);
+	lreq = lookup_linger_osdc(&osdc->linger_requests, cookie);
+	if (!lreq) {
+		dout("%s opcode %d cookie %llu dne\n", __func__, opcode,
+		     cookie);
+		goto out_unlock_osdc;
+	}
+
+	mutex_lock(&lreq->lock);
+	dout("%s opcode %d cookie %llu lreq %p is_watch %d\n", __func__,
+	     opcode, cookie, lreq, lreq->is_watch);
+	if (opcode == CEPH_WATCH_EVENT_DISCONNECT) {
+		if (!lreq->last_error) {
+			lreq->last_error = -ENOTCONN;
+			queue_watch_error(lreq);
+		}
+	} else if (!lreq->is_watch) {
+		/* CEPH_WATCH_EVENT_NOTIFY_COMPLETE */
+		if (lreq->notify_id && lreq->notify_id != notify_id) {
+			dout("lreq %p notify_id %llu != %llu, ignoring\n", lreq,
+			     lreq->notify_id, notify_id);
+		} else if (!completion_done(&lreq->notify_finish_wait)) {
+			struct ceph_msg_data *data =
+			    msg->num_data_items ? &msg->data[0] : NULL;
+
+			if (data) {
+				if (lreq->preply_pages) {
+					WARN_ON(data->type !=
+							CEPH_MSG_DATA_PAGES);
+					*lreq->preply_pages = data->pages;
+					*lreq->preply_len = data->length;
+					data->own_pages = false;
+				}
+			}
+			lreq->notify_finish_error = return_code;
+			complete_all(&lreq->notify_finish_wait);
+		}
+	} else {
+		/* CEPH_WATCH_EVENT_NOTIFY */
+		lwork = lwork_alloc(lreq, do_watch_notify);
+		if (!lwork) {
+			pr_err("failed to allocate notify-lwork\n");
+			goto out_unlock_lreq;
+		}
+
+		lwork->notify.notify_id = notify_id;
+		lwork->notify.notifier_id = notifier_id;
+		lwork->notify.payload = payload;
+		lwork->notify.payload_len = payload_len;
+		lwork->notify.msg = ceph_msg_get(msg);
+		lwork_queue(lwork);
+	}
+
+out_unlock_lreq:
+	mutex_unlock(&lreq->lock);
+out_unlock_osdc:
+	up_read(&osdc->lock);
+	return;
+
+bad:
+	pr_err("osdc handle_watch_notify corrupt msg\n");
+}
+
+/*
+ * Register request, send initial attempt.
+ */
+int ceph_osdc_start_request(struct ceph_osd_client *osdc,
+			    struct ceph_osd_request *req,
+			    bool nofail)
+{
+	down_read(&osdc->lock);
+	submit_request(req, false);
+	up_read(&osdc->lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(ceph_osdc_start_request);
+
+/*
+ * Unregister a registered request.  The request is not completed:
+ * ->r_result isn't set and __complete_request() isn't called.
+ */
+void ceph_osdc_cancel_request(struct ceph_osd_request *req)
+{
+	struct ceph_osd_client *osdc = req->r_osdc;
+
+	down_write(&osdc->lock);
+	if (req->r_osd)
+		cancel_request(req);
+	up_write(&osdc->lock);
+}
+EXPORT_SYMBOL(ceph_osdc_cancel_request);
+
+/*
+ * @timeout: in jiffies, 0 means "wait forever"
+ */
+static int wait_request_timeout(struct ceph_osd_request *req,
+				unsigned long timeout)
+{
+	long left;
+
+	dout("%s req %p tid %llu\n", __func__, req, req->r_tid);
+	left = wait_for_completion_killable_timeout(&req->r_completion,
+						ceph_timeout_jiffies(timeout));
+	if (left <= 0) {
+		left = left ?: -ETIMEDOUT;
+		ceph_osdc_cancel_request(req);
+	} else {
+		left = req->r_result; /* completed */
+	}
+
+	return left;
+}
+
+/*
+ * wait for a request to complete
+ */
+int ceph_osdc_wait_request(struct ceph_osd_client *osdc,
+			   struct ceph_osd_request *req)
+{
+	return wait_request_timeout(req, 0);
+}
+EXPORT_SYMBOL(ceph_osdc_wait_request);
+
+/*
+ * sync - wait for all in-flight requests to flush.  avoid starvation.
+ */
+void ceph_osdc_sync(struct ceph_osd_client *osdc)
+{
+	struct rb_node *n, *p;
+	u64 last_tid = atomic64_read(&osdc->last_tid);
+
+again:
+	down_read(&osdc->lock);
+	for (n = rb_first(&osdc->osds); n; n = rb_next(n)) {
+		struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node);
+
+		mutex_lock(&osd->lock);
+		for (p = rb_first(&osd->o_requests); p; p = rb_next(p)) {
+			struct ceph_osd_request *req =
+			    rb_entry(p, struct ceph_osd_request, r_node);
+
+			if (req->r_tid > last_tid)
+				break;
+
+			if (!(req->r_flags & CEPH_OSD_FLAG_WRITE))
+				continue;
+
+			ceph_osdc_get_request(req);
+			mutex_unlock(&osd->lock);
+			up_read(&osdc->lock);
+			dout("%s waiting on req %p tid %llu last_tid %llu\n",
+			     __func__, req, req->r_tid, last_tid);
+			wait_for_completion(&req->r_completion);
+			ceph_osdc_put_request(req);
+			goto again;
+		}
+
+		mutex_unlock(&osd->lock);
+	}
+
+	up_read(&osdc->lock);
+	dout("%s done last_tid %llu\n", __func__, last_tid);
+}
+EXPORT_SYMBOL(ceph_osdc_sync);
+
+/*
+ * Returns a handle, caller owns a ref.
+ */
+struct ceph_osd_linger_request *
+ceph_osdc_watch(struct ceph_osd_client *osdc,
+		struct ceph_object_id *oid,
+		struct ceph_object_locator *oloc,
+		rados_watchcb2_t wcb,
+		rados_watcherrcb_t errcb,
+		void *data)
+{
+	struct ceph_osd_linger_request *lreq;
+	int ret;
+
+	lreq = linger_alloc(osdc);
+	if (!lreq)
+		return ERR_PTR(-ENOMEM);
+
+	lreq->is_watch = true;
+	lreq->wcb = wcb;
+	lreq->errcb = errcb;
+	lreq->data = data;
+	lreq->watch_valid_thru = jiffies;
+
+	ceph_oid_copy(&lreq->t.base_oid, oid);
+	ceph_oloc_copy(&lreq->t.base_oloc, oloc);
+	lreq->t.flags = CEPH_OSD_FLAG_WRITE;
+	ktime_get_real_ts64(&lreq->mtime);
+
+	linger_submit(lreq);
+	ret = linger_reg_commit_wait(lreq);
+	if (ret) {
+		linger_cancel(lreq);
+		goto err_put_lreq;
+	}
+
+	return lreq;
+
+err_put_lreq:
+	linger_put(lreq);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(ceph_osdc_watch);
+
+/*
+ * Releases a ref.
+ *
+ * Times out after mount_timeout to preserve rbd unmap behaviour
+ * introduced in 2894e1d76974 ("rbd: timeout watch teardown on unmap
+ * with mount_timeout").
+ */
+int ceph_osdc_unwatch(struct ceph_osd_client *osdc,
+		      struct ceph_osd_linger_request *lreq)
+{
+	struct ceph_options *opts = osdc->client->options;
+	struct ceph_osd_request *req;
+	int ret;
+
+	req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO);
+	if (!req)
+		return -ENOMEM;
+
+	ceph_oid_copy(&req->r_base_oid, &lreq->t.base_oid);
+	ceph_oloc_copy(&req->r_base_oloc, &lreq->t.base_oloc);
+	req->r_flags = CEPH_OSD_FLAG_WRITE;
+	ktime_get_real_ts64(&req->r_mtime);
+	osd_req_op_watch_init(req, 0, CEPH_OSD_WATCH_OP_UNWATCH,
+			      lreq->linger_id, 0);
+
+	ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
+	if (ret)
+		goto out_put_req;
+
+	ceph_osdc_start_request(osdc, req, false);
+	linger_cancel(lreq);
+	linger_put(lreq);
+	ret = wait_request_timeout(req, opts->mount_timeout);
+
+out_put_req:
+	ceph_osdc_put_request(req);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_osdc_unwatch);
+
+static int osd_req_op_notify_ack_init(struct ceph_osd_request *req, int which,
+				      u64 notify_id, u64 cookie, void *payload,
+				      u32 payload_len)
+{
+	struct ceph_osd_req_op *op;
+	struct ceph_pagelist *pl;
+	int ret;
+
+	op = osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY_ACK, 0);
+
+	pl = ceph_pagelist_alloc(GFP_NOIO);
+	if (!pl)
+		return -ENOMEM;
+
+	ret = ceph_pagelist_encode_64(pl, notify_id);
+	ret |= ceph_pagelist_encode_64(pl, cookie);
+	if (payload) {
+		ret |= ceph_pagelist_encode_32(pl, payload_len);
+		ret |= ceph_pagelist_append(pl, payload, payload_len);
+	} else {
+		ret |= ceph_pagelist_encode_32(pl, 0);
+	}
+	if (ret) {
+		ceph_pagelist_release(pl);
+		return -ENOMEM;
+	}
+
+	ceph_osd_data_pagelist_init(&op->notify_ack.request_data, pl);
+	op->indata_len = pl->length;
+	return 0;
+}
+
+int ceph_osdc_notify_ack(struct ceph_osd_client *osdc,
+			 struct ceph_object_id *oid,
+			 struct ceph_object_locator *oloc,
+			 u64 notify_id,
+			 u64 cookie,
+			 void *payload,
+			 u32 payload_len)
+{
+	struct ceph_osd_request *req;
+	int ret;
+
+	req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO);
+	if (!req)
+		return -ENOMEM;
+
+	ceph_oid_copy(&req->r_base_oid, oid);
+	ceph_oloc_copy(&req->r_base_oloc, oloc);
+	req->r_flags = CEPH_OSD_FLAG_READ;
+
+	ret = osd_req_op_notify_ack_init(req, 0, notify_id, cookie, payload,
+					 payload_len);
+	if (ret)
+		goto out_put_req;
+
+	ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
+	if (ret)
+		goto out_put_req;
+
+	ceph_osdc_start_request(osdc, req, false);
+	ret = ceph_osdc_wait_request(osdc, req);
+
+out_put_req:
+	ceph_osdc_put_request(req);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_osdc_notify_ack);
+
+/*
+ * @timeout: in seconds
+ *
+ * @preply_{pages,len} are initialized both on success and error.
+ * The caller is responsible for:
+ *
+ *     ceph_release_page_vector(reply_pages, calc_pages_for(0, reply_len))
+ */
+int ceph_osdc_notify(struct ceph_osd_client *osdc,
+		     struct ceph_object_id *oid,
+		     struct ceph_object_locator *oloc,
+		     void *payload,
+		     u32 payload_len,
+		     u32 timeout,
+		     struct page ***preply_pages,
+		     size_t *preply_len)
+{
+	struct ceph_osd_linger_request *lreq;
+	int ret;
+
+	WARN_ON(!timeout);
+	if (preply_pages) {
+		*preply_pages = NULL;
+		*preply_len = 0;
+	}
+
+	lreq = linger_alloc(osdc);
+	if (!lreq)
+		return -ENOMEM;
+
+	lreq->request_pl = ceph_pagelist_alloc(GFP_NOIO);
+	if (!lreq->request_pl) {
+		ret = -ENOMEM;
+		goto out_put_lreq;
+	}
+
+	ret = ceph_pagelist_encode_32(lreq->request_pl, 1); /* prot_ver */
+	ret |= ceph_pagelist_encode_32(lreq->request_pl, timeout);
+	ret |= ceph_pagelist_encode_32(lreq->request_pl, payload_len);
+	ret |= ceph_pagelist_append(lreq->request_pl, payload, payload_len);
+	if (ret) {
+		ret = -ENOMEM;
+		goto out_put_lreq;
+	}
+
+	/* for notify_id */
+	lreq->notify_id_pages = ceph_alloc_page_vector(1, GFP_NOIO);
+	if (IS_ERR(lreq->notify_id_pages)) {
+		ret = PTR_ERR(lreq->notify_id_pages);
+		lreq->notify_id_pages = NULL;
+		goto out_put_lreq;
+	}
+
+	lreq->preply_pages = preply_pages;
+	lreq->preply_len = preply_len;
+
+	ceph_oid_copy(&lreq->t.base_oid, oid);
+	ceph_oloc_copy(&lreq->t.base_oloc, oloc);
+	lreq->t.flags = CEPH_OSD_FLAG_READ;
+
+	linger_submit(lreq);
+	ret = linger_reg_commit_wait(lreq);
+	if (!ret)
+		ret = linger_notify_finish_wait(lreq,
+				 msecs_to_jiffies(2 * timeout * MSEC_PER_SEC));
+	else
+		dout("lreq %p failed to initiate notify %d\n", lreq, ret);
+
+	linger_cancel(lreq);
+out_put_lreq:
+	linger_put(lreq);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_osdc_notify);
+
+/*
+ * Return the number of milliseconds since the watch was last
+ * confirmed, or an error.  If there is an error, the watch is no
+ * longer valid, and should be destroyed with ceph_osdc_unwatch().
+ */
+int ceph_osdc_watch_check(struct ceph_osd_client *osdc,
+			  struct ceph_osd_linger_request *lreq)
+{
+	unsigned long stamp, age;
+	int ret;
+
+	down_read(&osdc->lock);
+	mutex_lock(&lreq->lock);
+	stamp = lreq->watch_valid_thru;
+	if (!list_empty(&lreq->pending_lworks)) {
+		struct linger_work *lwork =
+		    list_first_entry(&lreq->pending_lworks,
+				     struct linger_work,
+				     pending_item);
+
+		if (time_before(lwork->queued_stamp, stamp))
+			stamp = lwork->queued_stamp;
+	}
+	age = jiffies - stamp;
+	dout("%s lreq %p linger_id %llu age %lu last_error %d\n", __func__,
+	     lreq, lreq->linger_id, age, lreq->last_error);
+	/* we are truncating to msecs, so return a safe upper bound */
+	ret = lreq->last_error ?: 1 + jiffies_to_msecs(age);
+
+	mutex_unlock(&lreq->lock);
+	up_read(&osdc->lock);
+	return ret;
+}
+
+static int decode_watcher(void **p, void *end, struct ceph_watch_item *item)
+{
+	u8 struct_v;
+	u32 struct_len;
+	int ret;
+
+	ret = ceph_start_decoding(p, end, 2, "watch_item_t",
+				  &struct_v, &struct_len);
+	if (ret)
+		goto bad;
+
+	ret = -EINVAL;
+	ceph_decode_copy_safe(p, end, &item->name, sizeof(item->name), bad);
+	ceph_decode_64_safe(p, end, item->cookie, bad);
+	ceph_decode_skip_32(p, end, bad); /* skip timeout seconds */
+
+	if (struct_v >= 2) {
+		ret = ceph_decode_entity_addr(p, end, &item->addr);
+		if (ret)
+			goto bad;
+	} else {
+		ret = 0;
+	}
+
+	dout("%s %s%llu cookie %llu addr %s\n", __func__,
+	     ENTITY_NAME(item->name), item->cookie,
+	     ceph_pr_addr(&item->addr));
+bad:
+	return ret;
+}
+
+static int decode_watchers(void **p, void *end,
+			   struct ceph_watch_item **watchers,
+			   u32 *num_watchers)
+{
+	u8 struct_v;
+	u32 struct_len;
+	int i;
+	int ret;
+
+	ret = ceph_start_decoding(p, end, 1, "obj_list_watch_response_t",
+				  &struct_v, &struct_len);
+	if (ret)
+		return ret;
+
+	*num_watchers = ceph_decode_32(p);
+	*watchers = kcalloc(*num_watchers, sizeof(**watchers), GFP_NOIO);
+	if (!*watchers)
+		return -ENOMEM;
+
+	for (i = 0; i < *num_watchers; i++) {
+		ret = decode_watcher(p, end, *watchers + i);
+		if (ret) {
+			kfree(*watchers);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * On success, the caller is responsible for:
+ *
+ *     kfree(watchers);
+ */
+int ceph_osdc_list_watchers(struct ceph_osd_client *osdc,
+			    struct ceph_object_id *oid,
+			    struct ceph_object_locator *oloc,
+			    struct ceph_watch_item **watchers,
+			    u32 *num_watchers)
+{
+	struct ceph_osd_request *req;
+	struct page **pages;
+	int ret;
+
+	req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO);
+	if (!req)
+		return -ENOMEM;
+
+	ceph_oid_copy(&req->r_base_oid, oid);
+	ceph_oloc_copy(&req->r_base_oloc, oloc);
+	req->r_flags = CEPH_OSD_FLAG_READ;
+
+	pages = ceph_alloc_page_vector(1, GFP_NOIO);
+	if (IS_ERR(pages)) {
+		ret = PTR_ERR(pages);
+		goto out_put_req;
+	}
+
+	osd_req_op_init(req, 0, CEPH_OSD_OP_LIST_WATCHERS, 0);
+	ceph_osd_data_pages_init(osd_req_op_data(req, 0, list_watchers,
+						 response_data),
+				 pages, PAGE_SIZE, 0, false, true);
+
+	ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
+	if (ret)
+		goto out_put_req;
+
+	ceph_osdc_start_request(osdc, req, false);
+	ret = ceph_osdc_wait_request(osdc, req);
+	if (ret >= 0) {
+		void *p = page_address(pages[0]);
+		void *const end = p + req->r_ops[0].outdata_len;
+
+		ret = decode_watchers(&p, end, watchers, num_watchers);
+	}
+
+out_put_req:
+	ceph_osdc_put_request(req);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_osdc_list_watchers);
+
+/*
+ * Call all pending notify callbacks - for use after a watch is
+ * unregistered, to make sure no more callbacks for it will be invoked
+ */
+void ceph_osdc_flush_notifies(struct ceph_osd_client *osdc)
+{
+	dout("%s osdc %p\n", __func__, osdc);
+	flush_workqueue(osdc->notify_wq);
+}
+EXPORT_SYMBOL(ceph_osdc_flush_notifies);
+
+void ceph_osdc_maybe_request_map(struct ceph_osd_client *osdc)
+{
+	down_read(&osdc->lock);
+	maybe_request_map(osdc);
+	up_read(&osdc->lock);
+}
+EXPORT_SYMBOL(ceph_osdc_maybe_request_map);
+
+/*
+ * Execute an OSD class method on an object.
+ *
+ * @flags: CEPH_OSD_FLAG_*
+ * @resp_len: in/out param for reply length
+ */
+int ceph_osdc_call(struct ceph_osd_client *osdc,
+		   struct ceph_object_id *oid,
+		   struct ceph_object_locator *oloc,
+		   const char *class, const char *method,
+		   unsigned int flags,
+		   struct page *req_page, size_t req_len,
+		   struct page **resp_pages, size_t *resp_len)
+{
+	struct ceph_osd_request *req;
+	int ret;
+
+	if (req_len > PAGE_SIZE)
+		return -E2BIG;
+
+	req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO);
+	if (!req)
+		return -ENOMEM;
+
+	ceph_oid_copy(&req->r_base_oid, oid);
+	ceph_oloc_copy(&req->r_base_oloc, oloc);
+	req->r_flags = flags;
+
+	ret = osd_req_op_cls_init(req, 0, class, method);
+	if (ret)
+		goto out_put_req;
+
+	if (req_page)
+		osd_req_op_cls_request_data_pages(req, 0, &req_page, req_len,
+						  0, false, false);
+	if (resp_pages)
+		osd_req_op_cls_response_data_pages(req, 0, resp_pages,
+						   *resp_len, 0, false, false);
+
+	ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
+	if (ret)
+		goto out_put_req;
+
+	ceph_osdc_start_request(osdc, req, false);
+	ret = ceph_osdc_wait_request(osdc, req);
+	if (ret >= 0) {
+		ret = req->r_ops[0].rval;
+		if (resp_pages)
+			*resp_len = req->r_ops[0].outdata_len;
+	}
+
+out_put_req:
+	ceph_osdc_put_request(req);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_osdc_call);
+
+/*
+ * reset all osd connections
+ */
+void ceph_osdc_reopen_osds(struct ceph_osd_client *osdc)
+{
+	struct rb_node *n;
+
+	down_write(&osdc->lock);
+	for (n = rb_first(&osdc->osds); n; ) {
+		struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node);
+
+		n = rb_next(n);
+		if (!reopen_osd(osd))
+			kick_osd_requests(osd);
+	}
+	up_write(&osdc->lock);
+}
+
+/*
+ * init, shutdown
+ */
+int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
+{
+	int err;
+
+	dout("init\n");
+	osdc->client = client;
+	init_rwsem(&osdc->lock);
+	osdc->osds = RB_ROOT;
+	INIT_LIST_HEAD(&osdc->osd_lru);
+	spin_lock_init(&osdc->osd_lru_lock);
+	osd_init(&osdc->homeless_osd);
+	osdc->homeless_osd.o_osdc = osdc;
+	osdc->homeless_osd.o_osd = CEPH_HOMELESS_OSD;
+	osdc->last_linger_id = CEPH_LINGER_ID_START;
+	osdc->linger_requests = RB_ROOT;
+	osdc->map_checks = RB_ROOT;
+	osdc->linger_map_checks = RB_ROOT;
+	INIT_DELAYED_WORK(&osdc->timeout_work, handle_timeout);
+	INIT_DELAYED_WORK(&osdc->osds_timeout_work, handle_osds_timeout);
+
+	err = -ENOMEM;
+	osdc->osdmap = ceph_osdmap_alloc();
+	if (!osdc->osdmap)
+		goto out;
+
+	osdc->req_mempool = mempool_create_slab_pool(10,
+						     ceph_osd_request_cache);
+	if (!osdc->req_mempool)
+		goto out_map;
+
+	err = ceph_msgpool_init(&osdc->msgpool_op, CEPH_MSG_OSD_OP,
+				PAGE_SIZE, CEPH_OSD_SLAB_OPS, 10, "osd_op");
+	if (err < 0)
+		goto out_mempool;
+	err = ceph_msgpool_init(&osdc->msgpool_op_reply, CEPH_MSG_OSD_OPREPLY,
+				PAGE_SIZE, CEPH_OSD_SLAB_OPS, 10,
+				"osd_op_reply");
+	if (err < 0)
+		goto out_msgpool;
+
+	err = -ENOMEM;
+	osdc->notify_wq = create_singlethread_workqueue("ceph-watch-notify");
+	if (!osdc->notify_wq)
+		goto out_msgpool_reply;
+
+	osdc->completion_wq = create_singlethread_workqueue("ceph-completion");
+	if (!osdc->completion_wq)
+		goto out_notify_wq;
+
+	schedule_delayed_work(&osdc->timeout_work,
+			      osdc->client->options->osd_keepalive_timeout);
+	schedule_delayed_work(&osdc->osds_timeout_work,
+	    round_jiffies_relative(osdc->client->options->osd_idle_ttl));
+
+	return 0;
+
+out_notify_wq:
+	destroy_workqueue(osdc->notify_wq);
+out_msgpool_reply:
+	ceph_msgpool_destroy(&osdc->msgpool_op_reply);
+out_msgpool:
+	ceph_msgpool_destroy(&osdc->msgpool_op);
+out_mempool:
+	mempool_destroy(osdc->req_mempool);
+out_map:
+	ceph_osdmap_destroy(osdc->osdmap);
+out:
+	return err;
+}
+
+void ceph_osdc_stop(struct ceph_osd_client *osdc)
+{
+	destroy_workqueue(osdc->completion_wq);
+	destroy_workqueue(osdc->notify_wq);
+	cancel_delayed_work_sync(&osdc->timeout_work);
+	cancel_delayed_work_sync(&osdc->osds_timeout_work);
+
+	down_write(&osdc->lock);
+	while (!RB_EMPTY_ROOT(&osdc->osds)) {
+		struct ceph_osd *osd = rb_entry(rb_first(&osdc->osds),
+						struct ceph_osd, o_node);
+		close_osd(osd);
+	}
+	up_write(&osdc->lock);
+	WARN_ON(refcount_read(&osdc->homeless_osd.o_ref) != 1);
+	osd_cleanup(&osdc->homeless_osd);
+
+	WARN_ON(!list_empty(&osdc->osd_lru));
+	WARN_ON(!RB_EMPTY_ROOT(&osdc->linger_requests));
+	WARN_ON(!RB_EMPTY_ROOT(&osdc->map_checks));
+	WARN_ON(!RB_EMPTY_ROOT(&osdc->linger_map_checks));
+	WARN_ON(atomic_read(&osdc->num_requests));
+	WARN_ON(atomic_read(&osdc->num_homeless));
+
+	ceph_osdmap_destroy(osdc->osdmap);
+	mempool_destroy(osdc->req_mempool);
+	ceph_msgpool_destroy(&osdc->msgpool_op);
+	ceph_msgpool_destroy(&osdc->msgpool_op_reply);
+}
+
+static int osd_req_op_copy_from_init(struct ceph_osd_request *req,
+				     u64 src_snapid, u64 src_version,
+				     struct ceph_object_id *src_oid,
+				     struct ceph_object_locator *src_oloc,
+				     u32 src_fadvise_flags,
+				     u32 dst_fadvise_flags,
+				     u32 truncate_seq, u64 truncate_size,
+				     u8 copy_from_flags)
+{
+	struct ceph_osd_req_op *op;
+	struct page **pages;
+	void *p, *end;
+
+	pages = ceph_alloc_page_vector(1, GFP_KERNEL);
+	if (IS_ERR(pages))
+		return PTR_ERR(pages);
+
+	op = osd_req_op_init(req, 0, CEPH_OSD_OP_COPY_FROM2,
+			     dst_fadvise_flags);
+	op->copy_from.snapid = src_snapid;
+	op->copy_from.src_version = src_version;
+	op->copy_from.flags = copy_from_flags;
+	op->copy_from.src_fadvise_flags = src_fadvise_flags;
+
+	p = page_address(pages[0]);
+	end = p + PAGE_SIZE;
+	ceph_encode_string(&p, end, src_oid->name, src_oid->name_len);
+	encode_oloc(&p, end, src_oloc);
+	ceph_encode_32(&p, truncate_seq);
+	ceph_encode_64(&p, truncate_size);
+	op->indata_len = PAGE_SIZE - (end - p);
+
+	ceph_osd_data_pages_init(&op->copy_from.osd_data, pages,
+				 op->indata_len, 0, false, true);
+	return 0;
+}
+
+int ceph_osdc_copy_from(struct ceph_osd_client *osdc,
+			u64 src_snapid, u64 src_version,
+			struct ceph_object_id *src_oid,
+			struct ceph_object_locator *src_oloc,
+			u32 src_fadvise_flags,
+			struct ceph_object_id *dst_oid,
+			struct ceph_object_locator *dst_oloc,
+			u32 dst_fadvise_flags,
+			u32 truncate_seq, u64 truncate_size,
+			u8 copy_from_flags)
+{
+	struct ceph_osd_request *req;
+	int ret;
+
+	req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+
+	req->r_flags = CEPH_OSD_FLAG_WRITE;
+
+	ceph_oloc_copy(&req->r_t.base_oloc, dst_oloc);
+	ceph_oid_copy(&req->r_t.base_oid, dst_oid);
+
+	ret = osd_req_op_copy_from_init(req, src_snapid, src_version, src_oid,
+					src_oloc, src_fadvise_flags,
+					dst_fadvise_flags, truncate_seq,
+					truncate_size, copy_from_flags);
+	if (ret)
+		goto out;
+
+	ret = ceph_osdc_alloc_messages(req, GFP_KERNEL);
+	if (ret)
+		goto out;
+
+	ceph_osdc_start_request(osdc, req, false);
+	ret = ceph_osdc_wait_request(osdc, req);
+
+out:
+	ceph_osdc_put_request(req);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_osdc_copy_from);
+
+int __init ceph_osdc_setup(void)
+{
+	size_t size = sizeof(struct ceph_osd_request) +
+	    CEPH_OSD_SLAB_OPS * sizeof(struct ceph_osd_req_op);
+
+	BUG_ON(ceph_osd_request_cache);
+	ceph_osd_request_cache = kmem_cache_create("ceph_osd_request", size,
+						   0, 0, NULL);
+
+	return ceph_osd_request_cache ? 0 : -ENOMEM;
+}
+
+void ceph_osdc_cleanup(void)
+{
+	BUG_ON(!ceph_osd_request_cache);
+	kmem_cache_destroy(ceph_osd_request_cache);
+	ceph_osd_request_cache = NULL;
+}
+
+/*
+ * handle incoming message
+ */
+static void dispatch(struct ceph_connection *con, struct ceph_msg *msg)
+{
+	struct ceph_osd *osd = con->private;
+	struct ceph_osd_client *osdc = osd->o_osdc;
+	int type = le16_to_cpu(msg->hdr.type);
+
+	switch (type) {
+	case CEPH_MSG_OSD_MAP:
+		ceph_osdc_handle_map(osdc, msg);
+		break;
+	case CEPH_MSG_OSD_OPREPLY:
+		handle_reply(osd, msg);
+		break;
+	case CEPH_MSG_OSD_BACKOFF:
+		handle_backoff(osd, msg);
+		break;
+	case CEPH_MSG_WATCH_NOTIFY:
+		handle_watch_notify(osdc, msg);
+		break;
+
+	default:
+		pr_err("received unknown message type %d %s\n", type,
+		       ceph_msg_type_name(type));
+	}
+
+	ceph_msg_put(msg);
+}
+
+/*
+ * Lookup and return message for incoming reply.  Don't try to do
+ * anything about a larger than preallocated data portion of the
+ * message at the moment - for now, just skip the message.
+ */
+static struct ceph_msg *get_reply(struct ceph_connection *con,
+				  struct ceph_msg_header *hdr,
+				  int *skip)
+{
+	struct ceph_osd *osd = con->private;
+	struct ceph_osd_client *osdc = osd->o_osdc;
+	struct ceph_msg *m = NULL;
+	struct ceph_osd_request *req;
+	int front_len = le32_to_cpu(hdr->front_len);
+	int data_len = le32_to_cpu(hdr->data_len);
+	u64 tid = le64_to_cpu(hdr->tid);
+
+	down_read(&osdc->lock);
+	if (!osd_registered(osd)) {
+		dout("%s osd%d unknown, skipping\n", __func__, osd->o_osd);
+		*skip = 1;
+		goto out_unlock_osdc;
+	}
+	WARN_ON(osd->o_osd != le64_to_cpu(hdr->src.num));
+
+	mutex_lock(&osd->lock);
+	req = lookup_request(&osd->o_requests, tid);
+	if (!req) {
+		dout("%s osd%d tid %llu unknown, skipping\n", __func__,
+		     osd->o_osd, tid);
+		*skip = 1;
+		goto out_unlock_session;
+	}
+
+	ceph_msg_revoke_incoming(req->r_reply);
+
+	if (front_len > req->r_reply->front_alloc_len) {
+		pr_warn("%s osd%d tid %llu front %d > preallocated %d\n",
+			__func__, osd->o_osd, req->r_tid, front_len,
+			req->r_reply->front_alloc_len);
+		m = ceph_msg_new(CEPH_MSG_OSD_OPREPLY, front_len, GFP_NOFS,
+				 false);
+		if (!m)
+			goto out_unlock_session;
+		ceph_msg_put(req->r_reply);
+		req->r_reply = m;
+	}
+
+	if (data_len > req->r_reply->data_length) {
+		pr_warn("%s osd%d tid %llu data %d > preallocated %zu, skipping\n",
+			__func__, osd->o_osd, req->r_tid, data_len,
+			req->r_reply->data_length);
+		m = NULL;
+		*skip = 1;
+		goto out_unlock_session;
+	}
+
+	m = ceph_msg_get(req->r_reply);
+	dout("get_reply tid %lld %p\n", tid, m);
+
+out_unlock_session:
+	mutex_unlock(&osd->lock);
+out_unlock_osdc:
+	up_read(&osdc->lock);
+	return m;
+}
+
+static struct ceph_msg *alloc_msg_with_page_vector(struct ceph_msg_header *hdr)
+{
+	struct ceph_msg *m;
+	int type = le16_to_cpu(hdr->type);
+	u32 front_len = le32_to_cpu(hdr->front_len);
+	u32 data_len = le32_to_cpu(hdr->data_len);
+
+	m = ceph_msg_new2(type, front_len, 1, GFP_NOIO, false);
+	if (!m)
+		return NULL;
+
+	if (data_len) {
+		struct page **pages;
+
+		pages = ceph_alloc_page_vector(calc_pages_for(0, data_len),
+					       GFP_NOIO);
+		if (IS_ERR(pages)) {
+			ceph_msg_put(m);
+			return NULL;
+		}
+
+		ceph_msg_data_add_pages(m, pages, data_len, 0, true);
+	}
+
+	return m;
+}
+
+static struct ceph_msg *alloc_msg(struct ceph_connection *con,
+				  struct ceph_msg_header *hdr,
+				  int *skip)
+{
+	struct ceph_osd *osd = con->private;
+	int type = le16_to_cpu(hdr->type);
+
+	*skip = 0;
+	switch (type) {
+	case CEPH_MSG_OSD_MAP:
+	case CEPH_MSG_OSD_BACKOFF:
+	case CEPH_MSG_WATCH_NOTIFY:
+		return alloc_msg_with_page_vector(hdr);
+	case CEPH_MSG_OSD_OPREPLY:
+		return get_reply(con, hdr, skip);
+	default:
+		pr_warn("%s osd%d unknown msg type %d, skipping\n", __func__,
+			osd->o_osd, type);
+		*skip = 1;
+		return NULL;
+	}
+}
+
+/*
+ * Wrappers to refcount containing ceph_osd struct
+ */
+static struct ceph_connection *get_osd_con(struct ceph_connection *con)
+{
+	struct ceph_osd *osd = con->private;
+	if (get_osd(osd))
+		return con;
+	return NULL;
+}
+
+static void put_osd_con(struct ceph_connection *con)
+{
+	struct ceph_osd *osd = con->private;
+	put_osd(osd);
+}
+
+/*
+ * authentication
+ */
+/*
+ * Note: returned pointer is the address of a structure that's
+ * managed separately.  Caller must *not* attempt to free it.
+ */
+static struct ceph_auth_handshake *get_authorizer(struct ceph_connection *con,
+					int *proto, int force_new)
+{
+	struct ceph_osd *o = con->private;
+	struct ceph_osd_client *osdc = o->o_osdc;
+	struct ceph_auth_client *ac = osdc->client->monc.auth;
+	struct ceph_auth_handshake *auth = &o->o_auth;
+
+	if (force_new && auth->authorizer) {
+		ceph_auth_destroy_authorizer(auth->authorizer);
+		auth->authorizer = NULL;
+	}
+	if (!auth->authorizer) {
+		int ret = ceph_auth_create_authorizer(ac, CEPH_ENTITY_TYPE_OSD,
+						      auth);
+		if (ret)
+			return ERR_PTR(ret);
+	} else {
+		int ret = ceph_auth_update_authorizer(ac, CEPH_ENTITY_TYPE_OSD,
+						     auth);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+	*proto = ac->protocol;
+
+	return auth;
+}
+
+static int add_authorizer_challenge(struct ceph_connection *con,
+				    void *challenge_buf, int challenge_buf_len)
+{
+	struct ceph_osd *o = con->private;
+	struct ceph_osd_client *osdc = o->o_osdc;
+	struct ceph_auth_client *ac = osdc->client->monc.auth;
+
+	return ceph_auth_add_authorizer_challenge(ac, o->o_auth.authorizer,
+					    challenge_buf, challenge_buf_len);
+}
+
+static int verify_authorizer_reply(struct ceph_connection *con)
+{
+	struct ceph_osd *o = con->private;
+	struct ceph_osd_client *osdc = o->o_osdc;
+	struct ceph_auth_client *ac = osdc->client->monc.auth;
+
+	return ceph_auth_verify_authorizer_reply(ac, o->o_auth.authorizer);
+}
+
+static int invalidate_authorizer(struct ceph_connection *con)
+{
+	struct ceph_osd *o = con->private;
+	struct ceph_osd_client *osdc = o->o_osdc;
+	struct ceph_auth_client *ac = osdc->client->monc.auth;
+
+	ceph_auth_invalidate_authorizer(ac, CEPH_ENTITY_TYPE_OSD);
+	return ceph_monc_validate_auth(&osdc->client->monc);
+}
+
+static void osd_reencode_message(struct ceph_msg *msg)
+{
+	int type = le16_to_cpu(msg->hdr.type);
+
+	if (type == CEPH_MSG_OSD_OP)
+		encode_request_finish(msg);
+}
+
+static int osd_sign_message(struct ceph_msg *msg)
+{
+	struct ceph_osd *o = msg->con->private;
+	struct ceph_auth_handshake *auth = &o->o_auth;
+
+	return ceph_auth_sign_message(auth, msg);
+}
+
+static int osd_check_message_signature(struct ceph_msg *msg)
+{
+	struct ceph_osd *o = msg->con->private;
+	struct ceph_auth_handshake *auth = &o->o_auth;
+
+	return ceph_auth_check_message_signature(auth, msg);
+}
+
+static const struct ceph_connection_operations osd_con_ops = {
+	.get = get_osd_con,
+	.put = put_osd_con,
+	.dispatch = dispatch,
+	.get_authorizer = get_authorizer,
+	.add_authorizer_challenge = add_authorizer_challenge,
+	.verify_authorizer_reply = verify_authorizer_reply,
+	.invalidate_authorizer = invalidate_authorizer,
+	.alloc_msg = alloc_msg,
+	.reencode_message = osd_reencode_message,
+	.sign_message = osd_sign_message,
+	.check_message_signature = osd_check_message_signature,
+	.fault = osd_fault,
+};