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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /fs/nfs/direct.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/nfs/direct.c')
-rw-r--r--fs/nfs/direct.c1058
1 files changed, 1058 insertions, 0 deletions
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
new file mode 100644
index 0000000000..5918c67dae
--- /dev/null
+++ b/fs/nfs/direct.c
@@ -0,0 +1,1058 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/nfs/direct.c
+ *
+ * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
+ *
+ * High-performance uncached I/O for the Linux NFS client
+ *
+ * There are important applications whose performance or correctness
+ * depends on uncached access to file data. Database clusters
+ * (multiple copies of the same instance running on separate hosts)
+ * implement their own cache coherency protocol that subsumes file
+ * system cache protocols. Applications that process datasets
+ * considerably larger than the client's memory do not always benefit
+ * from a local cache. A streaming video server, for instance, has no
+ * need to cache the contents of a file.
+ *
+ * When an application requests uncached I/O, all read and write requests
+ * are made directly to the server; data stored or fetched via these
+ * requests is not cached in the Linux page cache. The client does not
+ * correct unaligned requests from applications. All requested bytes are
+ * held on permanent storage before a direct write system call returns to
+ * an application.
+ *
+ * Solaris implements an uncached I/O facility called directio() that
+ * is used for backups and sequential I/O to very large files. Solaris
+ * also supports uncaching whole NFS partitions with "-o forcedirectio,"
+ * an undocumented mount option.
+ *
+ * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
+ * help from Andrew Morton.
+ *
+ * 18 Dec 2001 Initial implementation for 2.4 --cel
+ * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy
+ * 08 Jun 2003 Port to 2.5 APIs --cel
+ * 31 Mar 2004 Handle direct I/O without VFS support --cel
+ * 15 Sep 2004 Parallel async reads --cel
+ * 04 May 2005 support O_DIRECT with aio --cel
+ *
+ */
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/file.h>
+#include <linux/pagemap.h>
+#include <linux/kref.h>
+#include <linux/slab.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/module.h>
+
+#include <linux/nfs_fs.h>
+#include <linux/nfs_page.h>
+#include <linux/sunrpc/clnt.h>
+
+#include <linux/uaccess.h>
+#include <linux/atomic.h>
+
+#include "internal.h"
+#include "iostat.h"
+#include "pnfs.h"
+#include "fscache.h"
+#include "nfstrace.h"
+
+#define NFSDBG_FACILITY NFSDBG_VFS
+
+static struct kmem_cache *nfs_direct_cachep;
+
+static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
+static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq);
+static void nfs_direct_write_schedule_work(struct work_struct *work);
+
+static inline void get_dreq(struct nfs_direct_req *dreq)
+{
+ atomic_inc(&dreq->io_count);
+}
+
+static inline int put_dreq(struct nfs_direct_req *dreq)
+{
+ return atomic_dec_and_test(&dreq->io_count);
+}
+
+static void
+nfs_direct_handle_truncated(struct nfs_direct_req *dreq,
+ const struct nfs_pgio_header *hdr,
+ ssize_t dreq_len)
+{
+ if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) ||
+ test_bit(NFS_IOHDR_EOF, &hdr->flags)))
+ return;
+ if (dreq->max_count >= dreq_len) {
+ dreq->max_count = dreq_len;
+ if (dreq->count > dreq_len)
+ dreq->count = dreq_len;
+ }
+
+ if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && !dreq->error)
+ dreq->error = hdr->error;
+}
+
+static void
+nfs_direct_count_bytes(struct nfs_direct_req *dreq,
+ const struct nfs_pgio_header *hdr)
+{
+ loff_t hdr_end = hdr->io_start + hdr->good_bytes;
+ ssize_t dreq_len = 0;
+
+ if (hdr_end > dreq->io_start)
+ dreq_len = hdr_end - dreq->io_start;
+
+ nfs_direct_handle_truncated(dreq, hdr, dreq_len);
+
+ if (dreq_len > dreq->max_count)
+ dreq_len = dreq->max_count;
+
+ if (dreq->count < dreq_len)
+ dreq->count = dreq_len;
+}
+
+static void nfs_direct_truncate_request(struct nfs_direct_req *dreq,
+ struct nfs_page *req)
+{
+ loff_t offs = req_offset(req);
+ size_t req_start = (size_t)(offs - dreq->io_start);
+
+ if (req_start < dreq->max_count)
+ dreq->max_count = req_start;
+ if (req_start < dreq->count)
+ dreq->count = req_start;
+}
+
+/**
+ * nfs_swap_rw - NFS address space operation for swap I/O
+ * @iocb: target I/O control block
+ * @iter: I/O buffer
+ *
+ * Perform IO to the swap-file. This is much like direct IO.
+ */
+int nfs_swap_rw(struct kiocb *iocb, struct iov_iter *iter)
+{
+ ssize_t ret;
+
+ VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE);
+
+ if (iov_iter_rw(iter) == READ)
+ ret = nfs_file_direct_read(iocb, iter, true);
+ else
+ ret = nfs_file_direct_write(iocb, iter, true);
+ if (ret < 0)
+ return ret;
+ return 0;
+}
+
+static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
+{
+ unsigned int i;
+ for (i = 0; i < npages; i++)
+ put_page(pages[i]);
+}
+
+void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
+ struct nfs_direct_req *dreq)
+{
+ cinfo->inode = dreq->inode;
+ cinfo->mds = &dreq->mds_cinfo;
+ cinfo->ds = &dreq->ds_cinfo;
+ cinfo->dreq = dreq;
+ cinfo->completion_ops = &nfs_direct_commit_completion_ops;
+}
+
+static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
+{
+ struct nfs_direct_req *dreq;
+
+ dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
+ if (!dreq)
+ return NULL;
+
+ kref_init(&dreq->kref);
+ kref_get(&dreq->kref);
+ init_completion(&dreq->completion);
+ INIT_LIST_HEAD(&dreq->mds_cinfo.list);
+ pnfs_init_ds_commit_info(&dreq->ds_cinfo);
+ INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
+ spin_lock_init(&dreq->lock);
+
+ return dreq;
+}
+
+static void nfs_direct_req_free(struct kref *kref)
+{
+ struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
+
+ pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode);
+ if (dreq->l_ctx != NULL)
+ nfs_put_lock_context(dreq->l_ctx);
+ if (dreq->ctx != NULL)
+ put_nfs_open_context(dreq->ctx);
+ kmem_cache_free(nfs_direct_cachep, dreq);
+}
+
+static void nfs_direct_req_release(struct nfs_direct_req *dreq)
+{
+ kref_put(&dreq->kref, nfs_direct_req_free);
+}
+
+ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset)
+{
+ loff_t start = offset - dreq->io_start;
+ return dreq->max_count - start;
+}
+EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
+
+/*
+ * Collects and returns the final error value/byte-count.
+ */
+static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
+{
+ ssize_t result = -EIOCBQUEUED;
+
+ /* Async requests don't wait here */
+ if (dreq->iocb)
+ goto out;
+
+ result = wait_for_completion_killable(&dreq->completion);
+
+ if (!result) {
+ result = dreq->count;
+ WARN_ON_ONCE(dreq->count < 0);
+ }
+ if (!result)
+ result = dreq->error;
+
+out:
+ return (ssize_t) result;
+}
+
+/*
+ * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
+ * the iocb is still valid here if this is a synchronous request.
+ */
+static void nfs_direct_complete(struct nfs_direct_req *dreq)
+{
+ struct inode *inode = dreq->inode;
+
+ inode_dio_end(inode);
+
+ if (dreq->iocb) {
+ long res = (long) dreq->error;
+ if (dreq->count != 0) {
+ res = (long) dreq->count;
+ WARN_ON_ONCE(dreq->count < 0);
+ }
+ dreq->iocb->ki_complete(dreq->iocb, res);
+ }
+
+ complete(&dreq->completion);
+
+ nfs_direct_req_release(dreq);
+}
+
+static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
+{
+ unsigned long bytes = 0;
+ struct nfs_direct_req *dreq = hdr->dreq;
+
+ spin_lock(&dreq->lock);
+ if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+ spin_unlock(&dreq->lock);
+ goto out_put;
+ }
+
+ nfs_direct_count_bytes(dreq, hdr);
+ spin_unlock(&dreq->lock);
+
+ while (!list_empty(&hdr->pages)) {
+ struct nfs_page *req = nfs_list_entry(hdr->pages.next);
+ struct page *page = req->wb_page;
+
+ if (!PageCompound(page) && bytes < hdr->good_bytes &&
+ (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY))
+ set_page_dirty(page);
+ bytes += req->wb_bytes;
+ nfs_list_remove_request(req);
+ nfs_release_request(req);
+ }
+out_put:
+ if (put_dreq(dreq))
+ nfs_direct_complete(dreq);
+ hdr->release(hdr);
+}
+
+static void nfs_read_sync_pgio_error(struct list_head *head, int error)
+{
+ struct nfs_page *req;
+
+ while (!list_empty(head)) {
+ req = nfs_list_entry(head->next);
+ nfs_list_remove_request(req);
+ nfs_release_request(req);
+ }
+}
+
+static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
+{
+ get_dreq(hdr->dreq);
+}
+
+static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
+ .error_cleanup = nfs_read_sync_pgio_error,
+ .init_hdr = nfs_direct_pgio_init,
+ .completion = nfs_direct_read_completion,
+};
+
+/*
+ * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
+ * operation. If nfs_readdata_alloc() or get_user_pages() fails,
+ * bail and stop sending more reads. Read length accounting is
+ * handled automatically by nfs_direct_read_result(). Otherwise, if
+ * no requests have been sent, just return an error.
+ */
+
+static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
+ struct iov_iter *iter,
+ loff_t pos)
+{
+ struct nfs_pageio_descriptor desc;
+ struct inode *inode = dreq->inode;
+ ssize_t result = -EINVAL;
+ size_t requested_bytes = 0;
+ size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
+
+ nfs_pageio_init_read(&desc, dreq->inode, false,
+ &nfs_direct_read_completion_ops);
+ get_dreq(dreq);
+ desc.pg_dreq = dreq;
+ inode_dio_begin(inode);
+
+ while (iov_iter_count(iter)) {
+ struct page **pagevec;
+ size_t bytes;
+ size_t pgbase;
+ unsigned npages, i;
+
+ result = iov_iter_get_pages_alloc2(iter, &pagevec,
+ rsize, &pgbase);
+ if (result < 0)
+ break;
+
+ bytes = result;
+ npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
+ for (i = 0; i < npages; i++) {
+ struct nfs_page *req;
+ unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
+ /* XXX do we need to do the eof zeroing found in async_filler? */
+ req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
+ pgbase, pos, req_len);
+ if (IS_ERR(req)) {
+ result = PTR_ERR(req);
+ break;
+ }
+ if (!nfs_pageio_add_request(&desc, req)) {
+ result = desc.pg_error;
+ nfs_release_request(req);
+ break;
+ }
+ pgbase = 0;
+ bytes -= req_len;
+ requested_bytes += req_len;
+ pos += req_len;
+ dreq->bytes_left -= req_len;
+ }
+ nfs_direct_release_pages(pagevec, npages);
+ kvfree(pagevec);
+ if (result < 0)
+ break;
+ }
+
+ nfs_pageio_complete(&desc);
+
+ /*
+ * If no bytes were started, return the error, and let the
+ * generic layer handle the completion.
+ */
+ if (requested_bytes == 0) {
+ inode_dio_end(inode);
+ nfs_direct_req_release(dreq);
+ return result < 0 ? result : -EIO;
+ }
+
+ if (put_dreq(dreq))
+ nfs_direct_complete(dreq);
+ return requested_bytes;
+}
+
+/**
+ * nfs_file_direct_read - file direct read operation for NFS files
+ * @iocb: target I/O control block
+ * @iter: vector of user buffers into which to read data
+ * @swap: flag indicating this is swap IO, not O_DIRECT IO
+ *
+ * We use this function for direct reads instead of calling
+ * generic_file_aio_read() in order to avoid gfar's check to see if
+ * the request starts before the end of the file. For that check
+ * to work, we must generate a GETATTR before each direct read, and
+ * even then there is a window between the GETATTR and the subsequent
+ * READ where the file size could change. Our preference is simply
+ * to do all reads the application wants, and the server will take
+ * care of managing the end of file boundary.
+ *
+ * This function also eliminates unnecessarily updating the file's
+ * atime locally, as the NFS server sets the file's atime, and this
+ * client must read the updated atime from the server back into its
+ * cache.
+ */
+ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter,
+ bool swap)
+{
+ struct file *file = iocb->ki_filp;
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ struct nfs_direct_req *dreq;
+ struct nfs_lock_context *l_ctx;
+ ssize_t result, requested;
+ size_t count = iov_iter_count(iter);
+ nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
+
+ dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
+ file, count, (long long) iocb->ki_pos);
+
+ result = 0;
+ if (!count)
+ goto out;
+
+ task_io_account_read(count);
+
+ result = -ENOMEM;
+ dreq = nfs_direct_req_alloc();
+ if (dreq == NULL)
+ goto out;
+
+ dreq->inode = inode;
+ dreq->bytes_left = dreq->max_count = count;
+ dreq->io_start = iocb->ki_pos;
+ dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
+ l_ctx = nfs_get_lock_context(dreq->ctx);
+ if (IS_ERR(l_ctx)) {
+ result = PTR_ERR(l_ctx);
+ nfs_direct_req_release(dreq);
+ goto out_release;
+ }
+ dreq->l_ctx = l_ctx;
+ if (!is_sync_kiocb(iocb))
+ dreq->iocb = iocb;
+
+ if (user_backed_iter(iter))
+ dreq->flags = NFS_ODIRECT_SHOULD_DIRTY;
+
+ if (!swap)
+ nfs_start_io_direct(inode);
+
+ NFS_I(inode)->read_io += count;
+ requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
+
+ if (!swap)
+ nfs_end_io_direct(inode);
+
+ if (requested > 0) {
+ result = nfs_direct_wait(dreq);
+ if (result > 0) {
+ requested -= result;
+ iocb->ki_pos += result;
+ }
+ iov_iter_revert(iter, requested);
+ } else {
+ result = requested;
+ }
+
+out_release:
+ nfs_direct_req_release(dreq);
+out:
+ return result;
+}
+
+static void nfs_direct_add_page_head(struct list_head *list,
+ struct nfs_page *req)
+{
+ struct nfs_page *head = req->wb_head;
+
+ if (!list_empty(&head->wb_list) || !nfs_lock_request(head))
+ return;
+ if (!list_empty(&head->wb_list)) {
+ nfs_unlock_request(head);
+ return;
+ }
+ list_add(&head->wb_list, list);
+ kref_get(&head->wb_kref);
+ kref_get(&head->wb_kref);
+}
+
+static void nfs_direct_join_group(struct list_head *list,
+ struct nfs_commit_info *cinfo,
+ struct inode *inode)
+{
+ struct nfs_page *req, *subreq;
+
+ list_for_each_entry(req, list, wb_list) {
+ if (req->wb_head != req) {
+ nfs_direct_add_page_head(&req->wb_list, req);
+ continue;
+ }
+ subreq = req->wb_this_page;
+ if (subreq == req)
+ continue;
+ do {
+ /*
+ * Remove subrequests from this list before freeing
+ * them in the call to nfs_join_page_group().
+ */
+ if (!list_empty(&subreq->wb_list)) {
+ nfs_list_remove_request(subreq);
+ nfs_release_request(subreq);
+ }
+ } while ((subreq = subreq->wb_this_page) != req);
+ nfs_join_page_group(req, cinfo, inode);
+ }
+}
+
+static void
+nfs_direct_write_scan_commit_list(struct inode *inode,
+ struct list_head *list,
+ struct nfs_commit_info *cinfo)
+{
+ mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
+ pnfs_recover_commit_reqs(list, cinfo);
+ nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
+ mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
+}
+
+static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
+{
+ struct nfs_pageio_descriptor desc;
+ struct nfs_page *req;
+ LIST_HEAD(reqs);
+ struct nfs_commit_info cinfo;
+
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+ nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
+
+ nfs_direct_join_group(&reqs, &cinfo, dreq->inode);
+
+ nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
+ get_dreq(dreq);
+
+ nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
+ &nfs_direct_write_completion_ops);
+ desc.pg_dreq = dreq;
+
+ while (!list_empty(&reqs)) {
+ req = nfs_list_entry(reqs.next);
+ /* Bump the transmission count */
+ req->wb_nio++;
+ if (!nfs_pageio_add_request(&desc, req)) {
+ spin_lock(&dreq->lock);
+ if (dreq->error < 0) {
+ desc.pg_error = dreq->error;
+ } else if (desc.pg_error != -EAGAIN) {
+ dreq->flags = 0;
+ if (!desc.pg_error)
+ desc.pg_error = -EIO;
+ dreq->error = desc.pg_error;
+ } else
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ spin_unlock(&dreq->lock);
+ break;
+ }
+ nfs_release_request(req);
+ }
+ nfs_pageio_complete(&desc);
+
+ while (!list_empty(&reqs)) {
+ req = nfs_list_entry(reqs.next);
+ nfs_list_remove_request(req);
+ nfs_unlock_and_release_request(req);
+ if (desc.pg_error == -EAGAIN) {
+ nfs_mark_request_commit(req, NULL, &cinfo, 0);
+ } else {
+ spin_lock(&dreq->lock);
+ nfs_direct_truncate_request(dreq, req);
+ spin_unlock(&dreq->lock);
+ nfs_release_request(req);
+ }
+ }
+
+ if (put_dreq(dreq))
+ nfs_direct_write_complete(dreq);
+}
+
+static void nfs_direct_commit_complete(struct nfs_commit_data *data)
+{
+ const struct nfs_writeverf *verf = data->res.verf;
+ struct nfs_direct_req *dreq = data->dreq;
+ struct nfs_commit_info cinfo;
+ struct nfs_page *req;
+ int status = data->task.tk_status;
+
+ trace_nfs_direct_commit_complete(dreq);
+
+ if (status < 0) {
+ /* Errors in commit are fatal */
+ dreq->error = status;
+ dreq->flags = NFS_ODIRECT_DONE;
+ } else {
+ status = dreq->error;
+ }
+
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+
+ while (!list_empty(&data->pages)) {
+ req = nfs_list_entry(data->pages.next);
+ nfs_list_remove_request(req);
+ if (status < 0) {
+ spin_lock(&dreq->lock);
+ nfs_direct_truncate_request(dreq, req);
+ spin_unlock(&dreq->lock);
+ nfs_release_request(req);
+ } else if (!nfs_write_match_verf(verf, req)) {
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ /*
+ * Despite the reboot, the write was successful,
+ * so reset wb_nio.
+ */
+ req->wb_nio = 0;
+ nfs_mark_request_commit(req, NULL, &cinfo, 0);
+ } else
+ nfs_release_request(req);
+ nfs_unlock_and_release_request(req);
+ }
+
+ if (nfs_commit_end(cinfo.mds))
+ nfs_direct_write_complete(dreq);
+}
+
+static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
+ struct nfs_page *req)
+{
+ struct nfs_direct_req *dreq = cinfo->dreq;
+
+ trace_nfs_direct_resched_write(dreq);
+
+ spin_lock(&dreq->lock);
+ if (dreq->flags != NFS_ODIRECT_DONE)
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ spin_unlock(&dreq->lock);
+ nfs_mark_request_commit(req, NULL, cinfo, 0);
+}
+
+static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
+ .completion = nfs_direct_commit_complete,
+ .resched_write = nfs_direct_resched_write,
+};
+
+static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
+{
+ int res;
+ struct nfs_commit_info cinfo;
+ LIST_HEAD(mds_list);
+
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+ nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
+ res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
+ if (res < 0) /* res == -ENOMEM */
+ nfs_direct_write_reschedule(dreq);
+}
+
+static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq)
+{
+ struct nfs_commit_info cinfo;
+ struct nfs_page *req;
+ LIST_HEAD(reqs);
+
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+ nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
+
+ while (!list_empty(&reqs)) {
+ req = nfs_list_entry(reqs.next);
+ nfs_list_remove_request(req);
+ nfs_direct_truncate_request(dreq, req);
+ nfs_release_request(req);
+ nfs_unlock_and_release_request(req);
+ }
+}
+
+static void nfs_direct_write_schedule_work(struct work_struct *work)
+{
+ struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
+ int flags = dreq->flags;
+
+ dreq->flags = 0;
+ switch (flags) {
+ case NFS_ODIRECT_DO_COMMIT:
+ nfs_direct_commit_schedule(dreq);
+ break;
+ case NFS_ODIRECT_RESCHED_WRITES:
+ nfs_direct_write_reschedule(dreq);
+ break;
+ default:
+ nfs_direct_write_clear_reqs(dreq);
+ nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
+ nfs_direct_complete(dreq);
+ }
+}
+
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
+{
+ trace_nfs_direct_write_complete(dreq);
+ queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */
+}
+
+static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
+{
+ struct nfs_direct_req *dreq = hdr->dreq;
+ struct nfs_commit_info cinfo;
+ struct nfs_page *req = nfs_list_entry(hdr->pages.next);
+ int flags = NFS_ODIRECT_DONE;
+
+ trace_nfs_direct_write_completion(dreq);
+
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+
+ spin_lock(&dreq->lock);
+ if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+ spin_unlock(&dreq->lock);
+ goto out_put;
+ }
+
+ nfs_direct_count_bytes(dreq, hdr);
+ if (test_bit(NFS_IOHDR_UNSTABLE_WRITES, &hdr->flags) &&
+ !test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
+ if (!dreq->flags)
+ dreq->flags = NFS_ODIRECT_DO_COMMIT;
+ flags = dreq->flags;
+ }
+ spin_unlock(&dreq->lock);
+
+ while (!list_empty(&hdr->pages)) {
+
+ req = nfs_list_entry(hdr->pages.next);
+ nfs_list_remove_request(req);
+ if (flags == NFS_ODIRECT_DO_COMMIT) {
+ kref_get(&req->wb_kref);
+ memcpy(&req->wb_verf, &hdr->verf.verifier,
+ sizeof(req->wb_verf));
+ nfs_mark_request_commit(req, hdr->lseg, &cinfo,
+ hdr->ds_commit_idx);
+ } else if (flags == NFS_ODIRECT_RESCHED_WRITES) {
+ kref_get(&req->wb_kref);
+ nfs_mark_request_commit(req, NULL, &cinfo, 0);
+ }
+ nfs_unlock_and_release_request(req);
+ }
+
+out_put:
+ if (put_dreq(dreq))
+ nfs_direct_write_complete(dreq);
+ hdr->release(hdr);
+}
+
+static void nfs_write_sync_pgio_error(struct list_head *head, int error)
+{
+ struct nfs_page *req;
+
+ while (!list_empty(head)) {
+ req = nfs_list_entry(head->next);
+ nfs_list_remove_request(req);
+ nfs_unlock_and_release_request(req);
+ }
+}
+
+static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
+{
+ struct nfs_direct_req *dreq = hdr->dreq;
+ struct nfs_page *req;
+ struct nfs_commit_info cinfo;
+
+ trace_nfs_direct_write_reschedule_io(dreq);
+
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+ spin_lock(&dreq->lock);
+ if (dreq->error == 0)
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ set_bit(NFS_IOHDR_REDO, &hdr->flags);
+ spin_unlock(&dreq->lock);
+ while (!list_empty(&hdr->pages)) {
+ req = nfs_list_entry(hdr->pages.next);
+ nfs_list_remove_request(req);
+ nfs_unlock_request(req);
+ nfs_mark_request_commit(req, NULL, &cinfo, 0);
+ }
+}
+
+static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
+ .error_cleanup = nfs_write_sync_pgio_error,
+ .init_hdr = nfs_direct_pgio_init,
+ .completion = nfs_direct_write_completion,
+ .reschedule_io = nfs_direct_write_reschedule_io,
+};
+
+
+/*
+ * NB: Return the value of the first error return code. Subsequent
+ * errors after the first one are ignored.
+ */
+/*
+ * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
+ * operation. If nfs_writedata_alloc() or get_user_pages() fails,
+ * bail and stop sending more writes. Write length accounting is
+ * handled automatically by nfs_direct_write_result(). Otherwise, if
+ * no requests have been sent, just return an error.
+ */
+static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
+ struct iov_iter *iter,
+ loff_t pos, int ioflags)
+{
+ struct nfs_pageio_descriptor desc;
+ struct inode *inode = dreq->inode;
+ struct nfs_commit_info cinfo;
+ ssize_t result = 0;
+ size_t requested_bytes = 0;
+ size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
+ bool defer = false;
+
+ trace_nfs_direct_write_schedule_iovec(dreq);
+
+ nfs_pageio_init_write(&desc, inode, ioflags, false,
+ &nfs_direct_write_completion_ops);
+ desc.pg_dreq = dreq;
+ get_dreq(dreq);
+ inode_dio_begin(inode);
+
+ NFS_I(inode)->write_io += iov_iter_count(iter);
+ while (iov_iter_count(iter)) {
+ struct page **pagevec;
+ size_t bytes;
+ size_t pgbase;
+ unsigned npages, i;
+
+ result = iov_iter_get_pages_alloc2(iter, &pagevec,
+ wsize, &pgbase);
+ if (result < 0)
+ break;
+
+ bytes = result;
+ npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
+ for (i = 0; i < npages; i++) {
+ struct nfs_page *req;
+ unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
+
+ req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
+ pgbase, pos, req_len);
+ if (IS_ERR(req)) {
+ result = PTR_ERR(req);
+ break;
+ }
+
+ if (desc.pg_error < 0) {
+ nfs_free_request(req);
+ result = desc.pg_error;
+ break;
+ }
+
+ pgbase = 0;
+ bytes -= req_len;
+ requested_bytes += req_len;
+ pos += req_len;
+ dreq->bytes_left -= req_len;
+
+ if (defer) {
+ nfs_mark_request_commit(req, NULL, &cinfo, 0);
+ continue;
+ }
+
+ nfs_lock_request(req);
+ if (nfs_pageio_add_request(&desc, req))
+ continue;
+
+ /* Exit on hard errors */
+ if (desc.pg_error < 0 && desc.pg_error != -EAGAIN) {
+ result = desc.pg_error;
+ nfs_unlock_and_release_request(req);
+ break;
+ }
+
+ /* If the error is soft, defer remaining requests */
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+ spin_lock(&dreq->lock);
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ spin_unlock(&dreq->lock);
+ nfs_unlock_request(req);
+ nfs_mark_request_commit(req, NULL, &cinfo, 0);
+ desc.pg_error = 0;
+ defer = true;
+ }
+ nfs_direct_release_pages(pagevec, npages);
+ kvfree(pagevec);
+ if (result < 0)
+ break;
+ }
+ nfs_pageio_complete(&desc);
+
+ /*
+ * If no bytes were started, return the error, and let the
+ * generic layer handle the completion.
+ */
+ if (requested_bytes == 0) {
+ inode_dio_end(inode);
+ nfs_direct_req_release(dreq);
+ return result < 0 ? result : -EIO;
+ }
+
+ if (put_dreq(dreq))
+ nfs_direct_write_complete(dreq);
+ return requested_bytes;
+}
+
+/**
+ * nfs_file_direct_write - file direct write operation for NFS files
+ * @iocb: target I/O control block
+ * @iter: vector of user buffers from which to write data
+ * @swap: flag indicating this is swap IO, not O_DIRECT IO
+ *
+ * We use this function for direct writes instead of calling
+ * generic_file_aio_write() in order to avoid taking the inode
+ * semaphore and updating the i_size. The NFS server will set
+ * the new i_size and this client must read the updated size
+ * back into its cache. We let the server do generic write
+ * parameter checking and report problems.
+ *
+ * We eliminate local atime updates, see direct read above.
+ *
+ * We avoid unnecessary page cache invalidations for normal cached
+ * readers of this file.
+ *
+ * Note that O_APPEND is not supported for NFS direct writes, as there
+ * is no atomic O_APPEND write facility in the NFS protocol.
+ */
+ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter,
+ bool swap)
+{
+ ssize_t result, requested;
+ size_t count;
+ struct file *file = iocb->ki_filp;
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ struct nfs_direct_req *dreq;
+ struct nfs_lock_context *l_ctx;
+ loff_t pos, end;
+
+ dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
+ file, iov_iter_count(iter), (long long) iocb->ki_pos);
+
+ if (swap)
+ /* bypass generic checks */
+ result = iov_iter_count(iter);
+ else
+ result = generic_write_checks(iocb, iter);
+ if (result <= 0)
+ return result;
+ count = result;
+ nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
+
+ pos = iocb->ki_pos;
+ end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
+
+ task_io_account_write(count);
+
+ result = -ENOMEM;
+ dreq = nfs_direct_req_alloc();
+ if (!dreq)
+ goto out;
+
+ dreq->inode = inode;
+ dreq->bytes_left = dreq->max_count = count;
+ dreq->io_start = pos;
+ dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
+ l_ctx = nfs_get_lock_context(dreq->ctx);
+ if (IS_ERR(l_ctx)) {
+ result = PTR_ERR(l_ctx);
+ nfs_direct_req_release(dreq);
+ goto out_release;
+ }
+ dreq->l_ctx = l_ctx;
+ if (!is_sync_kiocb(iocb))
+ dreq->iocb = iocb;
+ pnfs_init_ds_commit_info_ops(&dreq->ds_cinfo, inode);
+
+ if (swap) {
+ requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
+ FLUSH_STABLE);
+ } else {
+ nfs_start_io_direct(inode);
+
+ requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
+ FLUSH_COND_STABLE);
+
+ if (mapping->nrpages) {
+ invalidate_inode_pages2_range(mapping,
+ pos >> PAGE_SHIFT, end);
+ }
+
+ nfs_end_io_direct(inode);
+ }
+
+ if (requested > 0) {
+ result = nfs_direct_wait(dreq);
+ if (result > 0) {
+ requested -= result;
+ iocb->ki_pos = pos + result;
+ /* XXX: should check the generic_write_sync retval */
+ generic_write_sync(iocb, result);
+ }
+ iov_iter_revert(iter, requested);
+ } else {
+ result = requested;
+ }
+ nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE);
+out_release:
+ nfs_direct_req_release(dreq);
+out:
+ return result;
+}
+
+/**
+ * nfs_init_directcache - create a slab cache for nfs_direct_req structures
+ *
+ */
+int __init nfs_init_directcache(void)
+{
+ nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
+ sizeof(struct nfs_direct_req),
+ 0, (SLAB_RECLAIM_ACCOUNT|
+ SLAB_MEM_SPREAD),
+ NULL);
+ if (nfs_direct_cachep == NULL)
+ return -ENOMEM;
+
+ return 0;
+}
+
+/**
+ * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
+ *
+ */
+void nfs_destroy_directcache(void)
+{
+ kmem_cache_destroy(nfs_direct_cachep);
+}