Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 2059 insertions, 0 deletions

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
new file mode 100644
index 000000000..de10899da
--- /dev/null
+++ b/fs/ceph/addr.c
@@ -0,0 +1,2059 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/backing-dev.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/writeback.h>	/* generic_writepages */
+#include <linux/slab.h>
+#include <linux/pagevec.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/signal.h>
+
+#include "super.h"
+#include "mds_client.h"
+#include "cache.h"
+#include <linux/ceph/osd_client.h>
+#include <linux/ceph/striper.h>
+
+/*
+ * Ceph address space ops.
+ *
+ * There are a few funny things going on here.
+ *
+ * The page->private field is used to reference a struct
+ * ceph_snap_context for _every_ dirty page.  This indicates which
+ * snapshot the page was logically dirtied in, and thus which snap
+ * context needs to be associated with the osd write during writeback.
+ *
+ * Similarly, struct ceph_inode_info maintains a set of counters to
+ * count dirty pages on the inode.  In the absence of snapshots,
+ * i_wrbuffer_ref == i_wrbuffer_ref_head == the dirty page count.
+ *
+ * When a snapshot is taken (that is, when the client receives
+ * notification that a snapshot was taken), each inode with caps and
+ * with dirty pages (dirty pages implies there is a cap) gets a new
+ * ceph_cap_snap in the i_cap_snaps list (which is sorted in ascending
+ * order, new snaps go to the tail).  The i_wrbuffer_ref_head count is
+ * moved to capsnap->dirty. (Unless a sync write is currently in
+ * progress.  In that case, the capsnap is said to be "pending", new
+ * writes cannot start, and the capsnap isn't "finalized" until the
+ * write completes (or fails) and a final size/mtime for the inode for
+ * that snap can be settled upon.)  i_wrbuffer_ref_head is reset to 0.
+ *
+ * On writeback, we must submit writes to the osd IN SNAP ORDER.  So,
+ * we look for the first capsnap in i_cap_snaps and write out pages in
+ * that snap context _only_.  Then we move on to the next capsnap,
+ * eventually reaching the "live" or "head" context (i.e., pages that
+ * are not yet snapped) and are writing the most recently dirtied
+ * pages.
+ *
+ * Invalidate and so forth must take care to ensure the dirty page
+ * accounting is preserved.
+ */
+
+#define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
+#define CONGESTION_OFF_THRESH(congestion_kb)				\
+	(CONGESTION_ON_THRESH(congestion_kb) -				\
+	 (CONGESTION_ON_THRESH(congestion_kb) >> 2))
+
+static inline struct ceph_snap_context *page_snap_context(struct page *page)
+{
+	if (PagePrivate(page))
+		return (void *)page->private;
+	return NULL;
+}
+
+/*
+ * Dirty a page.  Optimistically adjust accounting, on the assumption
+ * that we won't race with invalidate.  If we do, readjust.
+ */
+static int ceph_set_page_dirty(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode;
+	struct ceph_inode_info *ci;
+	struct ceph_snap_context *snapc;
+
+	if (PageDirty(page)) {
+		dout("%p set_page_dirty %p idx %lu -- already dirty\n",
+		     mapping->host, page, page->index);
+		BUG_ON(!PagePrivate(page));
+		return 0;
+	}
+
+	inode = mapping->host;
+	ci = ceph_inode(inode);
+
+	/* dirty the head */
+	spin_lock(&ci->i_ceph_lock);
+	BUG_ON(ci->i_wr_ref == 0); // caller should hold Fw reference
+	if (__ceph_have_pending_cap_snap(ci)) {
+		struct ceph_cap_snap *capsnap =
+				list_last_entry(&ci->i_cap_snaps,
+						struct ceph_cap_snap,
+						ci_item);
+		snapc = ceph_get_snap_context(capsnap->context);
+		capsnap->dirty_pages++;
+	} else {
+		BUG_ON(!ci->i_head_snapc);
+		snapc = ceph_get_snap_context(ci->i_head_snapc);
+		++ci->i_wrbuffer_ref_head;
+	}
+	if (ci->i_wrbuffer_ref == 0)
+		ihold(inode);
+	++ci->i_wrbuffer_ref;
+	dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
+	     "snapc %p seq %lld (%d snaps)\n",
+	     mapping->host, page, page->index,
+	     ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
+	     ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
+	     snapc, snapc->seq, snapc->num_snaps);
+	spin_unlock(&ci->i_ceph_lock);
+
+	/*
+	 * Reference snap context in page->private.  Also set
+	 * PagePrivate so that we get invalidatepage callback.
+	 */
+	BUG_ON(PagePrivate(page));
+	page->private = (unsigned long)snapc;
+	SetPagePrivate(page);
+
+	return __set_page_dirty_nobuffers(page);
+}
+
+/*
+ * If we are truncating the full page (i.e. offset == 0), adjust the
+ * dirty page counters appropriately.  Only called if there is private
+ * data on the page.
+ */
+static void ceph_invalidatepage(struct page *page, unsigned int offset,
+				unsigned int length)
+{
+	struct inode *inode;
+	struct ceph_inode_info *ci;
+	struct ceph_snap_context *snapc = page_snap_context(page);
+
+	inode = page->mapping->host;
+	ci = ceph_inode(inode);
+
+	if (offset != 0 || length != PAGE_SIZE) {
+		dout("%p invalidatepage %p idx %lu partial dirty page %u~%u\n",
+		     inode, page, page->index, offset, length);
+		return;
+	}
+
+	ceph_invalidate_fscache_page(inode, page);
+
+	WARN_ON(!PageLocked(page));
+	if (!PagePrivate(page))
+		return;
+
+	ClearPageChecked(page);
+
+	dout("%p invalidatepage %p idx %lu full dirty page\n",
+	     inode, page, page->index);
+
+	ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
+	ceph_put_snap_context(snapc);
+	page->private = 0;
+	ClearPagePrivate(page);
+}
+
+static int ceph_releasepage(struct page *page, gfp_t g)
+{
+	dout("%p releasepage %p idx %lu (%sdirty)\n", page->mapping->host,
+	     page, page->index, PageDirty(page) ? "" : "not ");
+
+	/* Can we release the page from the cache? */
+	if (!ceph_release_fscache_page(page, g))
+		return 0;
+
+	return !PagePrivate(page);
+}
+
+/*
+ * read a single page, without unlocking it.
+ */
+static int ceph_do_readpage(struct file *filp, struct page *page)
+{
+	struct inode *inode = file_inode(filp);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_osd_client *osdc =
+		&ceph_inode_to_client(inode)->client->osdc;
+	int err = 0;
+	u64 off = page_offset(page);
+	u64 len = PAGE_SIZE;
+
+	if (off >= i_size_read(inode)) {
+		zero_user_segment(page, 0, PAGE_SIZE);
+		SetPageUptodate(page);
+		return 0;
+	}
+
+	if (ci->i_inline_version != CEPH_INLINE_NONE) {
+		/*
+		 * Uptodate inline data should have been added
+		 * into page cache while getting Fcr caps.
+		 */
+		if (off == 0)
+			return -EINVAL;
+		zero_user_segment(page, 0, PAGE_SIZE);
+		SetPageUptodate(page);
+		return 0;
+	}
+
+	err = ceph_readpage_from_fscache(inode, page);
+	if (err == 0)
+		return -EINPROGRESS;
+
+	dout("readpage inode %p file %p page %p index %lu\n",
+	     inode, filp, page, page->index);
+	err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
+				  off, &len,
+				  ci->i_truncate_seq, ci->i_truncate_size,
+				  &page, 1, 0);
+	if (err == -ENOENT)
+		err = 0;
+	if (err < 0) {
+		SetPageError(page);
+		ceph_fscache_readpage_cancel(inode, page);
+		goto out;
+	}
+	if (err < PAGE_SIZE)
+		/* zero fill remainder of page */
+		zero_user_segment(page, err, PAGE_SIZE);
+	else
+		flush_dcache_page(page);
+
+	SetPageUptodate(page);
+	ceph_readpage_to_fscache(inode, page);
+
+out:
+	return err < 0 ? err : 0;
+}
+
+static int ceph_readpage(struct file *filp, struct page *page)
+{
+	int r = ceph_do_readpage(filp, page);
+	if (r != -EINPROGRESS)
+		unlock_page(page);
+	else
+		r = 0;
+	return r;
+}
+
+/*
+ * Finish an async read(ahead) op.
+ */
+static void finish_read(struct ceph_osd_request *req)
+{
+	struct inode *inode = req->r_inode;
+	struct ceph_osd_data *osd_data;
+	int rc = req->r_result <= 0 ? req->r_result : 0;
+	int bytes = req->r_result >= 0 ? req->r_result : 0;
+	int num_pages;
+	int i;
+
+	dout("finish_read %p req %p rc %d bytes %d\n", inode, req, rc, bytes);
+
+	/* unlock all pages, zeroing any data we didn't read */
+	osd_data = osd_req_op_extent_osd_data(req, 0);
+	BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
+	num_pages = calc_pages_for((u64)osd_data->alignment,
+					(u64)osd_data->length);
+	for (i = 0; i < num_pages; i++) {
+		struct page *page = osd_data->pages[i];
+
+		if (rc < 0 && rc != -ENOENT) {
+			ceph_fscache_readpage_cancel(inode, page);
+			goto unlock;
+		}
+		if (bytes < (int)PAGE_SIZE) {
+			/* zero (remainder of) page */
+			int s = bytes < 0 ? 0 : bytes;
+			zero_user_segment(page, s, PAGE_SIZE);
+		}
+ 		dout("finish_read %p uptodate %p idx %lu\n", inode, page,
+		     page->index);
+		flush_dcache_page(page);
+		SetPageUptodate(page);
+		ceph_readpage_to_fscache(inode, page);
+unlock:
+		unlock_page(page);
+		put_page(page);
+		bytes -= PAGE_SIZE;
+	}
+	kfree(osd_data->pages);
+}
+
+/*
+ * start an async read(ahead) operation.  return nr_pages we submitted
+ * a read for on success, or negative error code.
+ */
+static int start_read(struct inode *inode, struct ceph_rw_context *rw_ctx,
+		      struct list_head *page_list, int max)
+{
+	struct ceph_osd_client *osdc =
+		&ceph_inode_to_client(inode)->client->osdc;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct page *page = list_entry(page_list->prev, struct page, lru);
+	struct ceph_vino vino;
+	struct ceph_osd_request *req;
+	u64 off;
+	u64 len;
+	int i;
+	struct page **pages;
+	pgoff_t next_index;
+	int nr_pages = 0;
+	int got = 0;
+	int ret = 0;
+
+	if (!rw_ctx) {
+		/* caller of readpages does not hold buffer and read caps
+		 * (fadvise, madvise and readahead cases) */
+		int want = CEPH_CAP_FILE_CACHE;
+		ret = ceph_try_get_caps(ci, CEPH_CAP_FILE_RD, want, &got);
+		if (ret < 0) {
+			dout("start_read %p, error getting cap\n", inode);
+		} else if (!(got & want)) {
+			dout("start_read %p, no cache cap\n", inode);
+			ret = 0;
+		}
+		if (ret <= 0) {
+			if (got)
+				ceph_put_cap_refs(ci, got);
+			while (!list_empty(page_list)) {
+				page = list_entry(page_list->prev,
+						  struct page, lru);
+				list_del(&page->lru);
+				put_page(page);
+			}
+			return ret;
+		}
+	}
+
+	off = (u64) page_offset(page);
+
+	/* count pages */
+	next_index = page->index;
+	list_for_each_entry_reverse(page, page_list, lru) {
+		if (page->index != next_index)
+			break;
+		nr_pages++;
+		next_index++;
+		if (max && nr_pages == max)
+			break;
+	}
+	len = nr_pages << PAGE_SHIFT;
+	dout("start_read %p nr_pages %d is %lld~%lld\n", inode, nr_pages,
+	     off, len);
+	vino = ceph_vino(inode);
+	req = ceph_osdc_new_request(osdc, &ci->i_layout, vino, off, &len,
+				    0, 1, CEPH_OSD_OP_READ,
+				    CEPH_OSD_FLAG_READ, NULL,
+				    ci->i_truncate_seq, ci->i_truncate_size,
+				    false);
+	if (IS_ERR(req)) {
+		ret = PTR_ERR(req);
+		goto out;
+	}
+
+	/* build page vector */
+	nr_pages = calc_pages_for(0, len);
+	pages = kmalloc_array(nr_pages, sizeof(*pages), GFP_KERNEL);
+	if (!pages) {
+		ret = -ENOMEM;
+		goto out_put;
+	}
+	for (i = 0; i < nr_pages; ++i) {
+		page = list_entry(page_list->prev, struct page, lru);
+		BUG_ON(PageLocked(page));
+		list_del(&page->lru);
+
+ 		dout("start_read %p adding %p idx %lu\n", inode, page,
+		     page->index);
+		if (add_to_page_cache_lru(page, &inode->i_data, page->index,
+					  GFP_KERNEL)) {
+			ceph_fscache_uncache_page(inode, page);
+			put_page(page);
+			dout("start_read %p add_to_page_cache failed %p\n",
+			     inode, page);
+			nr_pages = i;
+			if (nr_pages > 0) {
+				len = nr_pages << PAGE_SHIFT;
+				osd_req_op_extent_update(req, 0, len);
+				break;
+			}
+			goto out_pages;
+		}
+		pages[i] = page;
+	}
+	osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0, false, false);
+	req->r_callback = finish_read;
+	req->r_inode = inode;
+
+	dout("start_read %p starting %p %lld~%lld\n", inode, req, off, len);
+	ret = ceph_osdc_start_request(osdc, req, false);
+	if (ret < 0)
+		goto out_pages;
+	ceph_osdc_put_request(req);
+
+	/* After adding locked pages to page cache, the inode holds cache cap.
+	 * So we can drop our cap refs. */
+	if (got)
+		ceph_put_cap_refs(ci, got);
+
+	return nr_pages;
+
+out_pages:
+	for (i = 0; i < nr_pages; ++i) {
+		ceph_fscache_readpage_cancel(inode, pages[i]);
+		unlock_page(pages[i]);
+	}
+	ceph_put_page_vector(pages, nr_pages, false);
+out_put:
+	ceph_osdc_put_request(req);
+out:
+	if (got)
+		ceph_put_cap_refs(ci, got);
+	return ret;
+}
+
+
+/*
+ * Read multiple pages.  Leave pages we don't read + unlock in page_list;
+ * the caller (VM) cleans them up.
+ */
+static int ceph_readpages(struct file *file, struct address_space *mapping,
+			  struct list_head *page_list, unsigned nr_pages)
+{
+	struct inode *inode = file_inode(file);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_file_info *fi = file->private_data;
+	struct ceph_rw_context *rw_ctx;
+	int rc = 0;
+	int max = 0;
+
+	if (ceph_inode(inode)->i_inline_version != CEPH_INLINE_NONE)
+		return -EINVAL;
+
+	rc = ceph_readpages_from_fscache(mapping->host, mapping, page_list,
+					 &nr_pages);
+
+	if (rc == 0)
+		goto out;
+
+	rw_ctx = ceph_find_rw_context(fi);
+	max = fsc->mount_options->rsize >> PAGE_SHIFT;
+	dout("readpages %p file %p ctx %p nr_pages %d max %d\n",
+	     inode, file, rw_ctx, nr_pages, max);
+	while (!list_empty(page_list)) {
+		rc = start_read(inode, rw_ctx, page_list, max);
+		if (rc < 0)
+			goto out;
+	}
+out:
+	ceph_fscache_readpages_cancel(inode, page_list);
+
+	dout("readpages %p file %p ret %d\n", inode, file, rc);
+	return rc;
+}
+
+struct ceph_writeback_ctl
+{
+	loff_t i_size;
+	u64 truncate_size;
+	u32 truncate_seq;
+	bool size_stable;
+	bool head_snapc;
+};
+
+/*
+ * Get ref for the oldest snapc for an inode with dirty data... that is, the
+ * only snap context we are allowed to write back.
+ */
+static struct ceph_snap_context *
+get_oldest_context(struct inode *inode, struct ceph_writeback_ctl *ctl,
+		   struct ceph_snap_context *page_snapc)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_snap_context *snapc = NULL;
+	struct ceph_cap_snap *capsnap = NULL;
+
+	spin_lock(&ci->i_ceph_lock);
+	list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
+		dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
+		     capsnap->context, capsnap->dirty_pages);
+		if (!capsnap->dirty_pages)
+			continue;
+
+		/* get i_size, truncate_{seq,size} for page_snapc? */
+		if (snapc && capsnap->context != page_snapc)
+			continue;
+
+		if (ctl) {
+			if (capsnap->writing) {
+				ctl->i_size = i_size_read(inode);
+				ctl->size_stable = false;
+			} else {
+				ctl->i_size = capsnap->size;
+				ctl->size_stable = true;
+			}
+			ctl->truncate_size = capsnap->truncate_size;
+			ctl->truncate_seq = capsnap->truncate_seq;
+			ctl->head_snapc = false;
+		}
+
+		if (snapc)
+			break;
+
+		snapc = ceph_get_snap_context(capsnap->context);
+		if (!page_snapc ||
+		    page_snapc == snapc ||
+		    page_snapc->seq > snapc->seq)
+			break;
+	}
+	if (!snapc && ci->i_wrbuffer_ref_head) {
+		snapc = ceph_get_snap_context(ci->i_head_snapc);
+		dout(" head snapc %p has %d dirty pages\n",
+		     snapc, ci->i_wrbuffer_ref_head);
+		if (ctl) {
+			ctl->i_size = i_size_read(inode);
+			ctl->truncate_size = ci->i_truncate_size;
+			ctl->truncate_seq = ci->i_truncate_seq;
+			ctl->size_stable = false;
+			ctl->head_snapc = true;
+		}
+	}
+	spin_unlock(&ci->i_ceph_lock);
+	return snapc;
+}
+
+static u64 get_writepages_data_length(struct inode *inode,
+				      struct page *page, u64 start)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_snap_context *snapc = page_snap_context(page);
+	struct ceph_cap_snap *capsnap = NULL;
+	u64 end = i_size_read(inode);
+
+	if (snapc != ci->i_head_snapc) {
+		bool found = false;
+		spin_lock(&ci->i_ceph_lock);
+		list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
+			if (capsnap->context == snapc) {
+				if (!capsnap->writing)
+					end = capsnap->size;
+				found = true;
+				break;
+			}
+		}
+		spin_unlock(&ci->i_ceph_lock);
+		WARN_ON(!found);
+	}
+	if (end > page_offset(page) + PAGE_SIZE)
+		end = page_offset(page) + PAGE_SIZE;
+	return end > start ? end - start : 0;
+}
+
+/*
+ * Write a single page, but leave the page locked.
+ *
+ * If we get a write error, set the page error bit, but still adjust the
+ * dirty page accounting (i.e., page is no longer dirty).
+ */
+static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
+{
+	struct inode *inode;
+	struct ceph_inode_info *ci;
+	struct ceph_fs_client *fsc;
+	struct ceph_snap_context *snapc, *oldest;
+	loff_t page_off = page_offset(page);
+	int err, len = PAGE_SIZE;
+	struct ceph_writeback_ctl ceph_wbc;
+
+	dout("writepage %p idx %lu\n", page, page->index);
+
+	inode = page->mapping->host;
+	ci = ceph_inode(inode);
+	fsc = ceph_inode_to_client(inode);
+
+	/* verify this is a writeable snap context */
+	snapc = page_snap_context(page);
+	if (!snapc) {
+		dout("writepage %p page %p not dirty?\n", inode, page);
+		return 0;
+	}
+	oldest = get_oldest_context(inode, &ceph_wbc, snapc);
+	if (snapc->seq > oldest->seq) {
+		dout("writepage %p page %p snapc %p not writeable - noop\n",
+		     inode, page, snapc);
+		/* we should only noop if called by kswapd */
+		WARN_ON(!(current->flags & PF_MEMALLOC));
+		ceph_put_snap_context(oldest);
+		redirty_page_for_writepage(wbc, page);
+		return 0;
+	}
+	ceph_put_snap_context(oldest);
+
+	/* is this a partial page at end of file? */
+	if (page_off >= ceph_wbc.i_size) {
+		dout("%p page eof %llu\n", page, ceph_wbc.i_size);
+		page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
+		return 0;
+	}
+
+	if (ceph_wbc.i_size < page_off + len)
+		len = ceph_wbc.i_size - page_off;
+
+	dout("writepage %p page %p index %lu on %llu~%u snapc %p seq %lld\n",
+	     inode, page, page->index, page_off, len, snapc, snapc->seq);
+
+	if (atomic_long_inc_return(&fsc->writeback_count) >
+	    CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
+		set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
+
+	set_page_writeback(page);
+	err = ceph_osdc_writepages(&fsc->client->osdc, ceph_vino(inode),
+				   &ci->i_layout, snapc, page_off, len,
+				   ceph_wbc.truncate_seq,
+				   ceph_wbc.truncate_size,
+				   &inode->i_mtime, &page, 1);
+	if (err < 0) {
+		struct writeback_control tmp_wbc;
+		if (!wbc)
+			wbc = &tmp_wbc;
+		if (err == -ERESTARTSYS) {
+			/* killed by SIGKILL */
+			dout("writepage interrupted page %p\n", page);
+			redirty_page_for_writepage(wbc, page);
+			end_page_writeback(page);
+			return err;
+		}
+		dout("writepage setting page/mapping error %d %p\n",
+		     err, page);
+		SetPageError(page);
+		mapping_set_error(&inode->i_data, err);
+		wbc->pages_skipped++;
+	} else {
+		dout("writepage cleaned page %p\n", page);
+		err = 0;  /* vfs expects us to return 0 */
+	}
+	page->private = 0;
+	ClearPagePrivate(page);
+	end_page_writeback(page);
+	ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
+	ceph_put_snap_context(snapc);  /* page's reference */
+
+	if (atomic_long_dec_return(&fsc->writeback_count) <
+	    CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
+		clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
+
+	return err;
+}
+
+static int ceph_writepage(struct page *page, struct writeback_control *wbc)
+{
+	int err;
+	struct inode *inode = page->mapping->host;
+	BUG_ON(!inode);
+	ihold(inode);
+	err = writepage_nounlock(page, wbc);
+	if (err == -ERESTARTSYS) {
+		/* direct memory reclaimer was killed by SIGKILL. return 0
+		 * to prevent caller from setting mapping/page error */
+		err = 0;
+	}
+	unlock_page(page);
+	iput(inode);
+	return err;
+}
+
+/*
+ * lame release_pages helper.  release_pages() isn't exported to
+ * modules.
+ */
+static void ceph_release_pages(struct page **pages, int num)
+{
+	struct pagevec pvec;
+	int i;
+
+	pagevec_init(&pvec);
+	for (i = 0; i < num; i++) {
+		if (pagevec_add(&pvec, pages[i]) == 0)
+			pagevec_release(&pvec);
+	}
+	pagevec_release(&pvec);
+}
+
+/*
+ * async writeback completion handler.
+ *
+ * If we get an error, set the mapping error bit, but not the individual
+ * page error bits.
+ */
+static void writepages_finish(struct ceph_osd_request *req)
+{
+	struct inode *inode = req->r_inode;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_osd_data *osd_data;
+	struct page *page;
+	int num_pages, total_pages = 0;
+	int i, j;
+	int rc = req->r_result;
+	struct ceph_snap_context *snapc = req->r_snapc;
+	struct address_space *mapping = inode->i_mapping;
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	bool remove_page;
+
+	dout("writepages_finish %p rc %d\n", inode, rc);
+	if (rc < 0) {
+		mapping_set_error(mapping, rc);
+		ceph_set_error_write(ci);
+	} else {
+		ceph_clear_error_write(ci);
+	}
+
+	/*
+	 * We lost the cache cap, need to truncate the page before
+	 * it is unlocked, otherwise we'd truncate it later in the
+	 * page truncation thread, possibly losing some data that
+	 * raced its way in
+	 */
+	remove_page = !(ceph_caps_issued(ci) &
+			(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO));
+
+	/* clean all pages */
+	for (i = 0; i < req->r_num_ops; i++) {
+		if (req->r_ops[i].op != CEPH_OSD_OP_WRITE)
+			break;
+
+		osd_data = osd_req_op_extent_osd_data(req, i);
+		BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
+		num_pages = calc_pages_for((u64)osd_data->alignment,
+					   (u64)osd_data->length);
+		total_pages += num_pages;
+		for (j = 0; j < num_pages; j++) {
+			page = osd_data->pages[j];
+			BUG_ON(!page);
+			WARN_ON(!PageUptodate(page));
+
+			if (atomic_long_dec_return(&fsc->writeback_count) <
+			     CONGESTION_OFF_THRESH(
+					fsc->mount_options->congestion_kb))
+				clear_bdi_congested(inode_to_bdi(inode),
+						    BLK_RW_ASYNC);
+
+			ceph_put_snap_context(page_snap_context(page));
+			page->private = 0;
+			ClearPagePrivate(page);
+			dout("unlocking %p\n", page);
+			end_page_writeback(page);
+
+			if (remove_page)
+				generic_error_remove_page(inode->i_mapping,
+							  page);
+
+			unlock_page(page);
+		}
+		dout("writepages_finish %p wrote %llu bytes cleaned %d pages\n",
+		     inode, osd_data->length, rc >= 0 ? num_pages : 0);
+
+		ceph_release_pages(osd_data->pages, num_pages);
+	}
+
+	ceph_put_wrbuffer_cap_refs(ci, total_pages, snapc);
+
+	osd_data = osd_req_op_extent_osd_data(req, 0);
+	if (osd_data->pages_from_pool)
+		mempool_free(osd_data->pages,
+			     ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
+	else
+		kfree(osd_data->pages);
+	ceph_osdc_put_request(req);
+}
+
+/*
+ * initiate async writeback
+ */
+static int ceph_writepages_start(struct address_space *mapping,
+				 struct writeback_control *wbc)
+{
+	struct inode *inode = mapping->host;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_vino vino = ceph_vino(inode);
+	pgoff_t index, start_index, end = -1;
+	struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
+	struct pagevec pvec;
+	int rc = 0;
+	unsigned int wsize = i_blocksize(inode);
+	struct ceph_osd_request *req = NULL;
+	struct ceph_writeback_ctl ceph_wbc;
+	bool should_loop, range_whole = false;
+	bool done = false;
+
+	dout("writepages_start %p (mode=%s)\n", inode,
+	     wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
+	     (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
+
+	if (READ_ONCE(fsc->mount_state) == CEPH_MOUNT_SHUTDOWN) {
+		if (ci->i_wrbuffer_ref > 0) {
+			pr_warn_ratelimited(
+				"writepage_start %p %lld forced umount\n",
+				inode, ceph_ino(inode));
+		}
+		mapping_set_error(mapping, -EIO);
+		return -EIO; /* we're in a forced umount, don't write! */
+	}
+	if (fsc->mount_options->wsize < wsize)
+		wsize = fsc->mount_options->wsize;
+
+	pagevec_init(&pvec);
+
+	start_index = wbc->range_cyclic ? mapping->writeback_index : 0;
+	index = start_index;
+
+retry:
+	/* find oldest snap context with dirty data */
+	snapc = get_oldest_context(inode, &ceph_wbc, NULL);
+	if (!snapc) {
+		/* hmm, why does writepages get called when there
+		   is no dirty data? */
+		dout(" no snap context with dirty data?\n");
+		goto out;
+	}
+	dout(" oldest snapc is %p seq %lld (%d snaps)\n",
+	     snapc, snapc->seq, snapc->num_snaps);
+
+	should_loop = false;
+	if (ceph_wbc.head_snapc && snapc != last_snapc) {
+		/* where to start/end? */
+		if (wbc->range_cyclic) {
+			index = start_index;
+			end = -1;
+			if (index > 0)
+				should_loop = true;
+			dout(" cyclic, start at %lu\n", index);
+		} else {
+			index = wbc->range_start >> PAGE_SHIFT;
+			end = wbc->range_end >> PAGE_SHIFT;
+			if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
+				range_whole = true;
+			dout(" not cyclic, %lu to %lu\n", index, end);
+		}
+	} else if (!ceph_wbc.head_snapc) {
+		/* Do not respect wbc->range_{start,end}. Dirty pages
+		 * in that range can be associated with newer snapc.
+		 * They are not writeable until we write all dirty pages
+		 * associated with 'snapc' get written */
+		if (index > 0)
+			should_loop = true;
+		dout(" non-head snapc, range whole\n");
+	}
+
+	ceph_put_snap_context(last_snapc);
+	last_snapc = snapc;
+
+	while (!done && index <= end) {
+		int num_ops = 0, op_idx;
+		unsigned i, pvec_pages, max_pages, locked_pages = 0;
+		struct page **pages = NULL, **data_pages;
+		mempool_t *pool = NULL;	/* Becomes non-null if mempool used */
+		struct page *page;
+		pgoff_t strip_unit_end = 0;
+		u64 offset = 0, len = 0;
+
+		max_pages = wsize >> PAGE_SHIFT;
+
+get_more_pages:
+		pvec_pages = pagevec_lookup_range_nr_tag(&pvec, mapping, &index,
+						end, PAGECACHE_TAG_DIRTY,
+						max_pages - locked_pages);
+		dout("pagevec_lookup_range_tag got %d\n", pvec_pages);
+		if (!pvec_pages && !locked_pages)
+			break;
+		for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
+			page = pvec.pages[i];
+			dout("? %p idx %lu\n", page, page->index);
+			if (locked_pages == 0)
+				lock_page(page);  /* first page */
+			else if (!trylock_page(page))
+				break;
+
+			/* only dirty pages, or our accounting breaks */
+			if (unlikely(!PageDirty(page)) ||
+			    unlikely(page->mapping != mapping)) {
+				dout("!dirty or !mapping %p\n", page);
+				unlock_page(page);
+				continue;
+			}
+			/* only if matching snap context */
+			pgsnapc = page_snap_context(page);
+			if (pgsnapc != snapc) {
+				dout("page snapc %p %lld != oldest %p %lld\n",
+				     pgsnapc, pgsnapc->seq, snapc, snapc->seq);
+				if (!should_loop &&
+				    !ceph_wbc.head_snapc &&
+				    wbc->sync_mode != WB_SYNC_NONE)
+					should_loop = true;
+				unlock_page(page);
+				continue;
+			}
+			if (page_offset(page) >= ceph_wbc.i_size) {
+				dout("%p page eof %llu\n",
+				     page, ceph_wbc.i_size);
+				if ((ceph_wbc.size_stable ||
+				    page_offset(page) >= i_size_read(inode)) &&
+				    clear_page_dirty_for_io(page))
+					mapping->a_ops->invalidatepage(page,
+								0, PAGE_SIZE);
+				unlock_page(page);
+				continue;
+			}
+			if (strip_unit_end && (page->index > strip_unit_end)) {
+				dout("end of strip unit %p\n", page);
+				unlock_page(page);
+				break;
+			}
+			if (PageWriteback(page)) {
+				if (wbc->sync_mode == WB_SYNC_NONE) {
+					dout("%p under writeback\n", page);
+					unlock_page(page);
+					continue;
+				}
+				dout("waiting on writeback %p\n", page);
+				wait_on_page_writeback(page);
+			}
+
+			if (!clear_page_dirty_for_io(page)) {
+				dout("%p !clear_page_dirty_for_io\n", page);
+				unlock_page(page);
+				continue;
+			}
+
+			/*
+			 * We have something to write.  If this is
+			 * the first locked page this time through,
+			 * calculate max possinle write size and
+			 * allocate a page array
+			 */
+			if (locked_pages == 0) {
+				u64 objnum;
+				u64 objoff;
+				u32 xlen;
+
+				/* prepare async write request */
+				offset = (u64)page_offset(page);
+				ceph_calc_file_object_mapping(&ci->i_layout,
+							      offset, wsize,
+							      &objnum, &objoff,
+							      &xlen);
+				len = xlen;
+
+				num_ops = 1;
+				strip_unit_end = page->index +
+					((len - 1) >> PAGE_SHIFT);
+
+				BUG_ON(pages);
+				max_pages = calc_pages_for(0, (u64)len);
+				pages = kmalloc_array(max_pages,
+						      sizeof(*pages),
+						      GFP_NOFS);
+				if (!pages) {
+					pool = fsc->wb_pagevec_pool;
+					pages = mempool_alloc(pool, GFP_NOFS);
+					BUG_ON(!pages);
+				}
+
+				len = 0;
+			} else if (page->index !=
+				   (offset + len) >> PAGE_SHIFT) {
+				if (num_ops >= (pool ?  CEPH_OSD_SLAB_OPS :
+							CEPH_OSD_MAX_OPS)) {
+					redirty_page_for_writepage(wbc, page);
+					unlock_page(page);
+					break;
+				}
+
+				num_ops++;
+				offset = (u64)page_offset(page);
+				len = 0;
+			}
+
+			/* note position of first page in pvec */
+			dout("%p will write page %p idx %lu\n",
+			     inode, page, page->index);
+
+			if (atomic_long_inc_return(&fsc->writeback_count) >
+			    CONGESTION_ON_THRESH(
+				    fsc->mount_options->congestion_kb)) {
+				set_bdi_congested(inode_to_bdi(inode),
+						  BLK_RW_ASYNC);
+			}
+
+
+			pages[locked_pages++] = page;
+			pvec.pages[i] = NULL;
+
+			len += PAGE_SIZE;
+		}
+
+		/* did we get anything? */
+		if (!locked_pages)
+			goto release_pvec_pages;
+		if (i) {
+			unsigned j, n = 0;
+			/* shift unused page to beginning of pvec */
+			for (j = 0; j < pvec_pages; j++) {
+				if (!pvec.pages[j])
+					continue;
+				if (n < j)
+					pvec.pages[n] = pvec.pages[j];
+				n++;
+			}
+			pvec.nr = n;
+
+			if (pvec_pages && i == pvec_pages &&
+			    locked_pages < max_pages) {
+				dout("reached end pvec, trying for more\n");
+				pagevec_release(&pvec);
+				goto get_more_pages;
+			}
+		}
+
+new_request:
+		offset = page_offset(pages[0]);
+		len = wsize;
+
+		req = ceph_osdc_new_request(&fsc->client->osdc,
+					&ci->i_layout, vino,
+					offset, &len, 0, num_ops,
+					CEPH_OSD_OP_WRITE, CEPH_OSD_FLAG_WRITE,
+					snapc, ceph_wbc.truncate_seq,
+					ceph_wbc.truncate_size, false);
+		if (IS_ERR(req)) {
+			req = ceph_osdc_new_request(&fsc->client->osdc,
+						&ci->i_layout, vino,
+						offset, &len, 0,
+						min(num_ops,
+						    CEPH_OSD_SLAB_OPS),
+						CEPH_OSD_OP_WRITE,
+						CEPH_OSD_FLAG_WRITE,
+						snapc, ceph_wbc.truncate_seq,
+						ceph_wbc.truncate_size, true);
+			BUG_ON(IS_ERR(req));
+		}
+		BUG_ON(len < page_offset(pages[locked_pages - 1]) +
+			     PAGE_SIZE - offset);
+
+		req->r_callback = writepages_finish;
+		req->r_inode = inode;
+
+		/* Format the osd request message and submit the write */
+		len = 0;
+		data_pages = pages;
+		op_idx = 0;
+		for (i = 0; i < locked_pages; i++) {
+			u64 cur_offset = page_offset(pages[i]);
+			if (offset + len != cur_offset) {
+				if (op_idx + 1 == req->r_num_ops)
+					break;
+				osd_req_op_extent_dup_last(req, op_idx,
+							   cur_offset - offset);
+				dout("writepages got pages at %llu~%llu\n",
+				     offset, len);
+				osd_req_op_extent_osd_data_pages(req, op_idx,
+							data_pages, len, 0,
+							!!pool, false);
+				osd_req_op_extent_update(req, op_idx, len);
+
+				len = 0;
+				offset = cur_offset; 
+				data_pages = pages + i;
+				op_idx++;
+			}
+
+			set_page_writeback(pages[i]);
+			len += PAGE_SIZE;
+		}
+
+		if (ceph_wbc.size_stable) {
+			len = min(len, ceph_wbc.i_size - offset);
+		} else if (i == locked_pages) {
+			/* writepages_finish() clears writeback pages
+			 * according to the data length, so make sure
+			 * data length covers all locked pages */
+			u64 min_len = len + 1 - PAGE_SIZE;
+			len = get_writepages_data_length(inode, pages[i - 1],
+							 offset);
+			len = max(len, min_len);
+		}
+		dout("writepages got pages at %llu~%llu\n", offset, len);
+
+		osd_req_op_extent_osd_data_pages(req, op_idx, data_pages, len,
+						 0, !!pool, false);
+		osd_req_op_extent_update(req, op_idx, len);
+
+		BUG_ON(op_idx + 1 != req->r_num_ops);
+
+		pool = NULL;
+		if (i < locked_pages) {
+			BUG_ON(num_ops <= req->r_num_ops);
+			num_ops -= req->r_num_ops;
+			locked_pages -= i;
+
+			/* allocate new pages array for next request */
+			data_pages = pages;
+			pages = kmalloc_array(locked_pages, sizeof(*pages),
+					      GFP_NOFS);
+			if (!pages) {
+				pool = fsc->wb_pagevec_pool;
+				pages = mempool_alloc(pool, GFP_NOFS);
+				BUG_ON(!pages);
+			}
+			memcpy(pages, data_pages + i,
+			       locked_pages * sizeof(*pages));
+			memset(data_pages + i, 0,
+			       locked_pages * sizeof(*pages));
+		} else {
+			BUG_ON(num_ops != req->r_num_ops);
+			index = pages[i - 1]->index + 1;
+			/* request message now owns the pages array */
+			pages = NULL;
+		}
+
+		req->r_mtime = inode->i_mtime;
+		rc = ceph_osdc_start_request(&fsc->client->osdc, req, true);
+		BUG_ON(rc);
+		req = NULL;
+
+		wbc->nr_to_write -= i;
+		if (pages)
+			goto new_request;
+
+		/*
+		 * We stop writing back only if we are not doing
+		 * integrity sync. In case of integrity sync we have to
+		 * keep going until we have written all the pages
+		 * we tagged for writeback prior to entering this loop.
+		 */
+		if (wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE)
+			done = true;
+
+release_pvec_pages:
+		dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
+		     pvec.nr ? pvec.pages[0] : NULL);
+		pagevec_release(&pvec);
+	}
+
+	if (should_loop && !done) {
+		/* more to do; loop back to beginning of file */
+		dout("writepages looping back to beginning of file\n");
+		end = start_index - 1; /* OK even when start_index == 0 */
+
+		/* to write dirty pages associated with next snapc,
+		 * we need to wait until current writes complete */
+		if (wbc->sync_mode != WB_SYNC_NONE &&
+		    start_index == 0 && /* all dirty pages were checked */
+		    !ceph_wbc.head_snapc) {
+			struct page *page;
+			unsigned i, nr;
+			index = 0;
+			while ((index <= end) &&
+			       (nr = pagevec_lookup_tag(&pvec, mapping, &index,
+						PAGECACHE_TAG_WRITEBACK))) {
+				for (i = 0; i < nr; i++) {
+					page = pvec.pages[i];
+					if (page_snap_context(page) != snapc)
+						continue;
+					wait_on_page_writeback(page);
+				}
+				pagevec_release(&pvec);
+				cond_resched();
+			}
+		}
+
+		start_index = 0;
+		index = 0;
+		goto retry;
+	}
+
+	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
+		mapping->writeback_index = index;
+
+out:
+	ceph_osdc_put_request(req);
+	ceph_put_snap_context(last_snapc);
+	dout("writepages dend - startone, rc = %d\n", rc);
+	return rc;
+}
+
+
+
+/*
+ * See if a given @snapc is either writeable, or already written.
+ */
+static int context_is_writeable_or_written(struct inode *inode,
+					   struct ceph_snap_context *snapc)
+{
+	struct ceph_snap_context *oldest = get_oldest_context(inode, NULL, NULL);
+	int ret = !oldest || snapc->seq <= oldest->seq;
+
+	ceph_put_snap_context(oldest);
+	return ret;
+}
+
+/*
+ * We are only allowed to write into/dirty the page if the page is
+ * clean, or already dirty within the same snap context.
+ *
+ * called with page locked.
+ * return success with page locked,
+ * or any failure (incl -EAGAIN) with page unlocked.
+ */
+static int ceph_update_writeable_page(struct file *file,
+			    loff_t pos, unsigned len,
+			    struct page *page)
+{
+	struct inode *inode = file_inode(file);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	loff_t page_off = pos & PAGE_MASK;
+	int pos_in_page = pos & ~PAGE_MASK;
+	int end_in_page = pos_in_page + len;
+	loff_t i_size;
+	int r;
+	struct ceph_snap_context *snapc, *oldest;
+
+	if (READ_ONCE(fsc->mount_state) == CEPH_MOUNT_SHUTDOWN) {
+		dout(" page %p forced umount\n", page);
+		unlock_page(page);
+		return -EIO;
+	}
+
+retry_locked:
+	/* writepages currently holds page lock, but if we change that later, */
+	wait_on_page_writeback(page);
+
+	snapc = page_snap_context(page);
+	if (snapc && snapc != ci->i_head_snapc) {
+		/*
+		 * this page is already dirty in another (older) snap
+		 * context!  is it writeable now?
+		 */
+		oldest = get_oldest_context(inode, NULL, NULL);
+		if (snapc->seq > oldest->seq) {
+			ceph_put_snap_context(oldest);
+			dout(" page %p snapc %p not current or oldest\n",
+			     page, snapc);
+			/*
+			 * queue for writeback, and wait for snapc to
+			 * be writeable or written
+			 */
+			snapc = ceph_get_snap_context(snapc);
+			unlock_page(page);
+			ceph_queue_writeback(inode);
+			r = wait_event_killable(ci->i_cap_wq,
+			       context_is_writeable_or_written(inode, snapc));
+			ceph_put_snap_context(snapc);
+			if (r == -ERESTARTSYS)
+				return r;
+			return -EAGAIN;
+		}
+		ceph_put_snap_context(oldest);
+
+		/* yay, writeable, do it now (without dropping page lock) */
+		dout(" page %p snapc %p not current, but oldest\n",
+		     page, snapc);
+		if (!clear_page_dirty_for_io(page))
+			goto retry_locked;
+		r = writepage_nounlock(page, NULL);
+		if (r < 0)
+			goto fail_unlock;
+		goto retry_locked;
+	}
+
+	if (PageUptodate(page)) {
+		dout(" page %p already uptodate\n", page);
+		return 0;
+	}
+
+	/* full page? */
+	if (pos_in_page == 0 && len == PAGE_SIZE)
+		return 0;
+
+	/* past end of file? */
+	i_size = i_size_read(inode);
+
+	if (page_off >= i_size ||
+	    (pos_in_page == 0 && (pos+len) >= i_size &&
+	     end_in_page - pos_in_page != PAGE_SIZE)) {
+		dout(" zeroing %p 0 - %d and %d - %d\n",
+		     page, pos_in_page, end_in_page, (int)PAGE_SIZE);
+		zero_user_segments(page,
+				   0, pos_in_page,
+				   end_in_page, PAGE_SIZE);
+		return 0;
+	}
+
+	/* we need to read it. */
+	r = ceph_do_readpage(file, page);
+	if (r < 0) {
+		if (r == -EINPROGRESS)
+			return -EAGAIN;
+		goto fail_unlock;
+	}
+	goto retry_locked;
+fail_unlock:
+	unlock_page(page);
+	return r;
+}
+
+/*
+ * We are only allowed to write into/dirty the page if the page is
+ * clean, or already dirty within the same snap context.
+ */
+static int ceph_write_begin(struct file *file, struct address_space *mapping,
+			    loff_t pos, unsigned len, unsigned flags,
+			    struct page **pagep, void **fsdata)
+{
+	struct inode *inode = file_inode(file);
+	struct page *page;
+	pgoff_t index = pos >> PAGE_SHIFT;
+	int r;
+
+	do {
+		/* get a page */
+		page = grab_cache_page_write_begin(mapping, index, 0);
+		if (!page)
+			return -ENOMEM;
+
+		dout("write_begin file %p inode %p page %p %d~%d\n", file,
+		     inode, page, (int)pos, (int)len);
+
+		r = ceph_update_writeable_page(file, pos, len, page);
+		if (r < 0)
+			put_page(page);
+		else
+			*pagep = page;
+	} while (r == -EAGAIN);
+
+	return r;
+}
+
+/*
+ * we don't do anything in here that simple_write_end doesn't do
+ * except adjust dirty page accounting
+ */
+static int ceph_write_end(struct file *file, struct address_space *mapping,
+			  loff_t pos, unsigned len, unsigned copied,
+			  struct page *page, void *fsdata)
+{
+	struct inode *inode = file_inode(file);
+	bool check_cap = false;
+
+	dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
+	     inode, page, (int)pos, (int)copied, (int)len);
+
+	/* zero the stale part of the page if we did a short copy */
+	if (!PageUptodate(page)) {
+		if (copied < len) {
+			copied = 0;
+			goto out;
+		}
+		SetPageUptodate(page);
+	}
+
+	/* did file size increase? */
+	if (pos+copied > i_size_read(inode))
+		check_cap = ceph_inode_set_size(inode, pos+copied);
+
+	set_page_dirty(page);
+
+out:
+	unlock_page(page);
+	put_page(page);
+
+	if (check_cap)
+		ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
+
+	return copied;
+}
+
+/*
+ * we set .direct_IO to indicate direct io is supported, but since we
+ * intercept O_DIRECT reads and writes early, this function should
+ * never get called.
+ */
+static ssize_t ceph_direct_io(struct kiocb *iocb, struct iov_iter *iter)
+{
+	WARN_ON(1);
+	return -EINVAL;
+}
+
+const struct address_space_operations ceph_aops = {
+	.readpage = ceph_readpage,
+	.readpages = ceph_readpages,
+	.writepage = ceph_writepage,
+	.writepages = ceph_writepages_start,
+	.write_begin = ceph_write_begin,
+	.write_end = ceph_write_end,
+	.set_page_dirty = ceph_set_page_dirty,
+	.invalidatepage = ceph_invalidatepage,
+	.releasepage = ceph_releasepage,
+	.direct_IO = ceph_direct_io,
+};
+
+static void ceph_block_sigs(sigset_t *oldset)
+{
+	sigset_t mask;
+	siginitsetinv(&mask, sigmask(SIGKILL));
+	sigprocmask(SIG_BLOCK, &mask, oldset);
+}
+
+static void ceph_restore_sigs(sigset_t *oldset)
+{
+	sigprocmask(SIG_SETMASK, oldset, NULL);
+}
+
+/*
+ * vm ops
+ */
+static vm_fault_t ceph_filemap_fault(struct vm_fault *vmf)
+{
+	struct vm_area_struct *vma = vmf->vma;
+	struct inode *inode = file_inode(vma->vm_file);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_file_info *fi = vma->vm_file->private_data;
+	struct page *pinned_page = NULL;
+	loff_t off = (loff_t)vmf->pgoff << PAGE_SHIFT;
+	int want, got, err;
+	sigset_t oldset;
+	vm_fault_t ret = VM_FAULT_SIGBUS;
+
+	ceph_block_sigs(&oldset);
+
+	dout("filemap_fault %p %llx.%llx %llu~%zd trying to get caps\n",
+	     inode, ceph_vinop(inode), off, (size_t)PAGE_SIZE);
+	if (fi->fmode & CEPH_FILE_MODE_LAZY)
+		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
+	else
+		want = CEPH_CAP_FILE_CACHE;
+
+	got = 0;
+	err = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, -1, &got, &pinned_page);
+	if (err < 0)
+		goto out_restore;
+
+	dout("filemap_fault %p %llu~%zd got cap refs on %s\n",
+	     inode, off, (size_t)PAGE_SIZE, ceph_cap_string(got));
+
+	if ((got & (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO)) ||
+	    ci->i_inline_version == CEPH_INLINE_NONE) {
+		CEPH_DEFINE_RW_CONTEXT(rw_ctx, got);
+		ceph_add_rw_context(fi, &rw_ctx);
+		ret = filemap_fault(vmf);
+		ceph_del_rw_context(fi, &rw_ctx);
+		dout("filemap_fault %p %llu~%zd drop cap refs %s ret %x\n",
+			inode, off, (size_t)PAGE_SIZE,
+				ceph_cap_string(got), ret);
+	} else
+		err = -EAGAIN;
+
+	if (pinned_page)
+		put_page(pinned_page);
+	ceph_put_cap_refs(ci, got);
+
+	if (err != -EAGAIN)
+		goto out_restore;
+
+	/* read inline data */
+	if (off >= PAGE_SIZE) {
+		/* does not support inline data > PAGE_SIZE */
+		ret = VM_FAULT_SIGBUS;
+	} else {
+		struct address_space *mapping = inode->i_mapping;
+		struct page *page = find_or_create_page(mapping, 0,
+						mapping_gfp_constraint(mapping,
+						~__GFP_FS));
+		if (!page) {
+			ret = VM_FAULT_OOM;
+			goto out_inline;
+		}
+		err = __ceph_do_getattr(inode, page,
+					 CEPH_STAT_CAP_INLINE_DATA, true);
+		if (err < 0 || off >= i_size_read(inode)) {
+			unlock_page(page);
+			put_page(page);
+			if (err == -ENOMEM)
+				ret = VM_FAULT_OOM;
+			else
+				ret = VM_FAULT_SIGBUS;
+			goto out_inline;
+		}
+		if (err < PAGE_SIZE)
+			zero_user_segment(page, err, PAGE_SIZE);
+		else
+			flush_dcache_page(page);
+		SetPageUptodate(page);
+		vmf->page = page;
+		ret = VM_FAULT_MAJOR | VM_FAULT_LOCKED;
+out_inline:
+		dout("filemap_fault %p %llu~%zd read inline data ret %x\n",
+		     inode, off, (size_t)PAGE_SIZE, ret);
+	}
+out_restore:
+	ceph_restore_sigs(&oldset);
+	if (err < 0)
+		ret = vmf_error(err);
+
+	return ret;
+}
+
+/*
+ * Reuse write_begin here for simplicity.
+ */
+static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
+{
+	struct vm_area_struct *vma = vmf->vma;
+	struct inode *inode = file_inode(vma->vm_file);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_file_info *fi = vma->vm_file->private_data;
+	struct ceph_cap_flush *prealloc_cf;
+	struct page *page = vmf->page;
+	loff_t off = page_offset(page);
+	loff_t size = i_size_read(inode);
+	size_t len;
+	int want, got, err;
+	sigset_t oldset;
+	vm_fault_t ret = VM_FAULT_SIGBUS;
+
+	prealloc_cf = ceph_alloc_cap_flush();
+	if (!prealloc_cf)
+		return VM_FAULT_OOM;
+
+	ceph_block_sigs(&oldset);
+
+	if (ci->i_inline_version != CEPH_INLINE_NONE) {
+		struct page *locked_page = NULL;
+		if (off == 0) {
+			lock_page(page);
+			locked_page = page;
+		}
+		err = ceph_uninline_data(vma->vm_file, locked_page);
+		if (locked_page)
+			unlock_page(locked_page);
+		if (err < 0)
+			goto out_free;
+	}
+
+	if (off + PAGE_SIZE <= size)
+		len = PAGE_SIZE;
+	else
+		len = size & ~PAGE_MASK;
+
+	dout("page_mkwrite %p %llx.%llx %llu~%zd getting caps i_size %llu\n",
+	     inode, ceph_vinop(inode), off, len, size);
+	if (fi->fmode & CEPH_FILE_MODE_LAZY)
+		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
+	else
+		want = CEPH_CAP_FILE_BUFFER;
+
+	got = 0;
+	err = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, off + len,
+			    &got, NULL);
+	if (err < 0)
+		goto out_free;
+
+	dout("page_mkwrite %p %llu~%zd got cap refs on %s\n",
+	     inode, off, len, ceph_cap_string(got));
+
+	/* Update time before taking page lock */
+	file_update_time(vma->vm_file);
+
+	do {
+		lock_page(page);
+
+		if ((off > size) || (page->mapping != inode->i_mapping)) {
+			unlock_page(page);
+			ret = VM_FAULT_NOPAGE;
+			break;
+		}
+
+		err = ceph_update_writeable_page(vma->vm_file, off, len, page);
+		if (err >= 0) {
+			/* success.  we'll keep the page locked. */
+			set_page_dirty(page);
+			ret = VM_FAULT_LOCKED;
+		}
+	} while (err == -EAGAIN);
+
+	if (ret == VM_FAULT_LOCKED ||
+	    ci->i_inline_version != CEPH_INLINE_NONE) {
+		int dirty;
+		spin_lock(&ci->i_ceph_lock);
+		ci->i_inline_version = CEPH_INLINE_NONE;
+		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR,
+					       &prealloc_cf);
+		spin_unlock(&ci->i_ceph_lock);
+		if (dirty)
+			__mark_inode_dirty(inode, dirty);
+	}
+
+	dout("page_mkwrite %p %llu~%zd dropping cap refs on %s ret %x\n",
+	     inode, off, len, ceph_cap_string(got), ret);
+	ceph_put_cap_refs(ci, got);
+out_free:
+	ceph_restore_sigs(&oldset);
+	ceph_free_cap_flush(prealloc_cf);
+	if (err < 0)
+		ret = vmf_error(err);
+	return ret;
+}
+
+void ceph_fill_inline_data(struct inode *inode, struct page *locked_page,
+			   char	*data, size_t len)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct page *page;
+
+	if (locked_page) {
+		page = locked_page;
+	} else {
+		if (i_size_read(inode) == 0)
+			return;
+		page = find_or_create_page(mapping, 0,
+					   mapping_gfp_constraint(mapping,
+					   ~__GFP_FS));
+		if (!page)
+			return;
+		if (PageUptodate(page)) {
+			unlock_page(page);
+			put_page(page);
+			return;
+		}
+	}
+
+	dout("fill_inline_data %p %llx.%llx len %zu locked_page %p\n",
+	     inode, ceph_vinop(inode), len, locked_page);
+
+	if (len > 0) {
+		void *kaddr = kmap_atomic(page);
+		memcpy(kaddr, data, len);
+		kunmap_atomic(kaddr);
+	}
+
+	if (page != locked_page) {
+		if (len < PAGE_SIZE)
+			zero_user_segment(page, len, PAGE_SIZE);
+		else
+			flush_dcache_page(page);
+
+		SetPageUptodate(page);
+		unlock_page(page);
+		put_page(page);
+	}
+}
+
+int ceph_uninline_data(struct file *filp, struct page *locked_page)
+{
+	struct inode *inode = file_inode(filp);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_osd_request *req;
+	struct page *page = NULL;
+	u64 len, inline_version;
+	int err = 0;
+	bool from_pagecache = false;
+
+	spin_lock(&ci->i_ceph_lock);
+	inline_version = ci->i_inline_version;
+	spin_unlock(&ci->i_ceph_lock);
+
+	dout("uninline_data %p %llx.%llx inline_version %llu\n",
+	     inode, ceph_vinop(inode), inline_version);
+
+	if (inline_version == 1 || /* initial version, no data */
+	    inline_version == CEPH_INLINE_NONE)
+		goto out;
+
+	if (locked_page) {
+		page = locked_page;
+		WARN_ON(!PageUptodate(page));
+	} else if (ceph_caps_issued(ci) &
+		   (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) {
+		page = find_get_page(inode->i_mapping, 0);
+		if (page) {
+			if (PageUptodate(page)) {
+				from_pagecache = true;
+				lock_page(page);
+			} else {
+				put_page(page);
+				page = NULL;
+			}
+		}
+	}
+
+	if (page) {
+		len = i_size_read(inode);
+		if (len > PAGE_SIZE)
+			len = PAGE_SIZE;
+	} else {
+		page = __page_cache_alloc(GFP_NOFS);
+		if (!page) {
+			err = -ENOMEM;
+			goto out;
+		}
+		err = __ceph_do_getattr(inode, page,
+					CEPH_STAT_CAP_INLINE_DATA, true);
+		if (err < 0) {
+			/* no inline data */
+			if (err == -ENODATA)
+				err = 0;
+			goto out;
+		}
+		len = err;
+	}
+
+	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
+				    ceph_vino(inode), 0, &len, 0, 1,
+				    CEPH_OSD_OP_CREATE, CEPH_OSD_FLAG_WRITE,
+				    NULL, 0, 0, false);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto out;
+	}
+
+	req->r_mtime = inode->i_mtime;
+	err = ceph_osdc_start_request(&fsc->client->osdc, req, false);
+	if (!err)
+		err = ceph_osdc_wait_request(&fsc->client->osdc, req);
+	ceph_osdc_put_request(req);
+	if (err < 0)
+		goto out;
+
+	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
+				    ceph_vino(inode), 0, &len, 1, 3,
+				    CEPH_OSD_OP_WRITE, CEPH_OSD_FLAG_WRITE,
+				    NULL, ci->i_truncate_seq,
+				    ci->i_truncate_size, false);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto out;
+	}
+
+	osd_req_op_extent_osd_data_pages(req, 1, &page, len, 0, false, false);
+
+	{
+		__le64 xattr_buf = cpu_to_le64(inline_version);
+		err = osd_req_op_xattr_init(req, 0, CEPH_OSD_OP_CMPXATTR,
+					    "inline_version", &xattr_buf,
+					    sizeof(xattr_buf),
+					    CEPH_OSD_CMPXATTR_OP_GT,
+					    CEPH_OSD_CMPXATTR_MODE_U64);
+		if (err)
+			goto out_put;
+	}
+
+	{
+		char xattr_buf[32];
+		int xattr_len = snprintf(xattr_buf, sizeof(xattr_buf),
+					 "%llu", inline_version);
+		err = osd_req_op_xattr_init(req, 2, CEPH_OSD_OP_SETXATTR,
+					    "inline_version",
+					    xattr_buf, xattr_len, 0, 0);
+		if (err)
+			goto out_put;
+	}
+
+	req->r_mtime = inode->i_mtime;
+	err = ceph_osdc_start_request(&fsc->client->osdc, req, false);
+	if (!err)
+		err = ceph_osdc_wait_request(&fsc->client->osdc, req);
+out_put:
+	ceph_osdc_put_request(req);
+	if (err == -ECANCELED)
+		err = 0;
+out:
+	if (page && page != locked_page) {
+		if (from_pagecache) {
+			unlock_page(page);
+			put_page(page);
+		} else
+			__free_pages(page, 0);
+	}
+
+	dout("uninline_data %p %llx.%llx inline_version %llu = %d\n",
+	     inode, ceph_vinop(inode), inline_version, err);
+	return err;
+}
+
+static const struct vm_operations_struct ceph_vmops = {
+	.fault		= ceph_filemap_fault,
+	.page_mkwrite	= ceph_page_mkwrite,
+};
+
+int ceph_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct address_space *mapping = file->f_mapping;
+
+	if (!mapping->a_ops->readpage)
+		return -ENOEXEC;
+	file_accessed(file);
+	vma->vm_ops = &ceph_vmops;
+	return 0;
+}
+
+enum {
+	POOL_READ	= 1,
+	POOL_WRITE	= 2,
+};
+
+static int __ceph_pool_perm_get(struct ceph_inode_info *ci,
+				s64 pool, struct ceph_string *pool_ns)
+{
+	struct ceph_fs_client *fsc = ceph_inode_to_client(&ci->vfs_inode);
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_osd_request *rd_req = NULL, *wr_req = NULL;
+	struct rb_node **p, *parent;
+	struct ceph_pool_perm *perm;
+	struct page **pages;
+	size_t pool_ns_len;
+	int err = 0, err2 = 0, have = 0;
+
+	down_read(&mdsc->pool_perm_rwsem);
+	p = &mdsc->pool_perm_tree.rb_node;
+	while (*p) {
+		perm = rb_entry(*p, struct ceph_pool_perm, node);
+		if (pool < perm->pool)
+			p = &(*p)->rb_left;
+		else if (pool > perm->pool)
+			p = &(*p)->rb_right;
+		else {
+			int ret = ceph_compare_string(pool_ns,
+						perm->pool_ns,
+						perm->pool_ns_len);
+			if (ret < 0)
+				p = &(*p)->rb_left;
+			else if (ret > 0)
+				p = &(*p)->rb_right;
+			else {
+				have = perm->perm;
+				break;
+			}
+		}
+	}
+	up_read(&mdsc->pool_perm_rwsem);
+	if (*p)
+		goto out;
+
+	if (pool_ns)
+		dout("__ceph_pool_perm_get pool %lld ns %.*s no perm cached\n",
+		     pool, (int)pool_ns->len, pool_ns->str);
+	else
+		dout("__ceph_pool_perm_get pool %lld no perm cached\n", pool);
+
+	down_write(&mdsc->pool_perm_rwsem);
+	p = &mdsc->pool_perm_tree.rb_node;
+	parent = NULL;
+	while (*p) {
+		parent = *p;
+		perm = rb_entry(parent, struct ceph_pool_perm, node);
+		if (pool < perm->pool)
+			p = &(*p)->rb_left;
+		else if (pool > perm->pool)
+			p = &(*p)->rb_right;
+		else {
+			int ret = ceph_compare_string(pool_ns,
+						perm->pool_ns,
+						perm->pool_ns_len);
+			if (ret < 0)
+				p = &(*p)->rb_left;
+			else if (ret > 0)
+				p = &(*p)->rb_right;
+			else {
+				have = perm->perm;
+				break;
+			}
+		}
+	}
+	if (*p) {
+		up_write(&mdsc->pool_perm_rwsem);
+		goto out;
+	}
+
+	rd_req = ceph_osdc_alloc_request(&fsc->client->osdc, NULL,
+					 1, false, GFP_NOFS);
+	if (!rd_req) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+
+	rd_req->r_flags = CEPH_OSD_FLAG_READ;
+	osd_req_op_init(rd_req, 0, CEPH_OSD_OP_STAT, 0);
+	rd_req->r_base_oloc.pool = pool;
+	if (pool_ns)
+		rd_req->r_base_oloc.pool_ns = ceph_get_string(pool_ns);
+	ceph_oid_printf(&rd_req->r_base_oid, "%llx.00000000", ci->i_vino.ino);
+
+	err = ceph_osdc_alloc_messages(rd_req, GFP_NOFS);
+	if (err)
+		goto out_unlock;
+
+	wr_req = ceph_osdc_alloc_request(&fsc->client->osdc, NULL,
+					 1, false, GFP_NOFS);
+	if (!wr_req) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+
+	wr_req->r_flags = CEPH_OSD_FLAG_WRITE;
+	osd_req_op_init(wr_req, 0, CEPH_OSD_OP_CREATE, CEPH_OSD_OP_FLAG_EXCL);
+	ceph_oloc_copy(&wr_req->r_base_oloc, &rd_req->r_base_oloc);
+	ceph_oid_copy(&wr_req->r_base_oid, &rd_req->r_base_oid);
+
+	err = ceph_osdc_alloc_messages(wr_req, GFP_NOFS);
+	if (err)
+		goto out_unlock;
+
+	/* one page should be large enough for STAT data */
+	pages = ceph_alloc_page_vector(1, GFP_KERNEL);
+	if (IS_ERR(pages)) {
+		err = PTR_ERR(pages);
+		goto out_unlock;
+	}
+
+	osd_req_op_raw_data_in_pages(rd_req, 0, pages, PAGE_SIZE,
+				     0, false, true);
+	err = ceph_osdc_start_request(&fsc->client->osdc, rd_req, false);
+
+	wr_req->r_mtime = ci->vfs_inode.i_mtime;
+	err2 = ceph_osdc_start_request(&fsc->client->osdc, wr_req, false);
+
+	if (!err)
+		err = ceph_osdc_wait_request(&fsc->client->osdc, rd_req);
+	if (!err2)
+		err2 = ceph_osdc_wait_request(&fsc->client->osdc, wr_req);
+
+	if (err >= 0 || err == -ENOENT)
+		have |= POOL_READ;
+	else if (err != -EPERM)
+		goto out_unlock;
+
+	if (err2 == 0 || err2 == -EEXIST)
+		have |= POOL_WRITE;
+	else if (err2 != -EPERM) {
+		err = err2;
+		goto out_unlock;
+	}
+
+	pool_ns_len = pool_ns ? pool_ns->len : 0;
+	perm = kmalloc(sizeof(*perm) + pool_ns_len + 1, GFP_NOFS);
+	if (!perm) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+
+	perm->pool = pool;
+	perm->perm = have;
+	perm->pool_ns_len = pool_ns_len;
+	if (pool_ns_len > 0)
+		memcpy(perm->pool_ns, pool_ns->str, pool_ns_len);
+	perm->pool_ns[pool_ns_len] = 0;
+
+	rb_link_node(&perm->node, parent, p);
+	rb_insert_color(&perm->node, &mdsc->pool_perm_tree);
+	err = 0;
+out_unlock:
+	up_write(&mdsc->pool_perm_rwsem);
+
+	ceph_osdc_put_request(rd_req);
+	ceph_osdc_put_request(wr_req);
+out:
+	if (!err)
+		err = have;
+	if (pool_ns)
+		dout("__ceph_pool_perm_get pool %lld ns %.*s result = %d\n",
+		     pool, (int)pool_ns->len, pool_ns->str, err);
+	else
+		dout("__ceph_pool_perm_get pool %lld result = %d\n", pool, err);
+	return err;
+}
+
+int ceph_pool_perm_check(struct ceph_inode_info *ci, int need)
+{
+	s64 pool;
+	struct ceph_string *pool_ns;
+	int ret, flags;
+
+	if (ci->i_vino.snap != CEPH_NOSNAP) {
+		/*
+		 * Pool permission check needs to write to the first object.
+		 * But for snapshot, head of the first object may have alread
+		 * been deleted. Skip check to avoid creating orphan object.
+		 */
+		return 0;
+	}
+
+	if (ceph_test_mount_opt(ceph_inode_to_client(&ci->vfs_inode),
+				NOPOOLPERM))
+		return 0;
+
+	spin_lock(&ci->i_ceph_lock);
+	flags = ci->i_ceph_flags;
+	pool = ci->i_layout.pool_id;
+	spin_unlock(&ci->i_ceph_lock);
+check:
+	if (flags & CEPH_I_POOL_PERM) {
+		if ((need & CEPH_CAP_FILE_RD) && !(flags & CEPH_I_POOL_RD)) {
+			dout("ceph_pool_perm_check pool %lld no read perm\n",
+			     pool);
+			return -EPERM;
+		}
+		if ((need & CEPH_CAP_FILE_WR) && !(flags & CEPH_I_POOL_WR)) {
+			dout("ceph_pool_perm_check pool %lld no write perm\n",
+			     pool);
+			return -EPERM;
+		}
+		return 0;
+	}
+
+	pool_ns = ceph_try_get_string(ci->i_layout.pool_ns);
+	ret = __ceph_pool_perm_get(ci, pool, pool_ns);
+	ceph_put_string(pool_ns);
+	if (ret < 0)
+		return ret;
+
+	flags = CEPH_I_POOL_PERM;
+	if (ret & POOL_READ)
+		flags |= CEPH_I_POOL_RD;
+	if (ret & POOL_WRITE)
+		flags |= CEPH_I_POOL_WR;
+
+	spin_lock(&ci->i_ceph_lock);
+	if (pool == ci->i_layout.pool_id &&
+	    pool_ns == rcu_dereference_raw(ci->i_layout.pool_ns)) {
+		ci->i_ceph_flags |= flags;
+        } else {
+		pool = ci->i_layout.pool_id;
+		flags = ci->i_ceph_flags;
+	}
+	spin_unlock(&ci->i_ceph_lock);
+	goto check;
+}
+
+void ceph_pool_perm_destroy(struct ceph_mds_client *mdsc)
+{
+	struct ceph_pool_perm *perm;
+	struct rb_node *n;
+
+	while (!RB_EMPTY_ROOT(&mdsc->pool_perm_tree)) {
+		n = rb_first(&mdsc->pool_perm_tree);
+		perm = rb_entry(n, struct ceph_pool_perm, node);
+		rb_erase(n, &mdsc->pool_perm_tree);
+		kfree(perm);
+	}
+}