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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * linux/fs/nfs/direct.c
- *
- * Copyright (C) 2003 by Chuck Lever <[email protected]>
- *
- * 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 = hdr->error;
- else /* Clear outstanding error if this is EOF */
- dreq->error = 0;
- }
- }
- 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;
- }
- /**
- * 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)
- {
- return dreq->bytes_left;
- }
- 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_create_request(dreq->ctx, pagevec[i],
- pgbase, req_len);
- if (IS_ERR(req)) {
- result = PTR_ERR(req);
- break;
- }
- req->wb_index = pos >> PAGE_SHIFT;
- req->wb_offset = pos & ~PAGE_MASK;
- 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 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, 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, *tmp;
- LIST_HEAD(reqs);
- struct nfs_commit_info cinfo;
- LIST_HEAD(failed);
- nfs_init_cinfo_from_dreq(&cinfo, dreq);
- nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
- nfs_direct_join_group(&reqs, dreq->inode);
- dreq->count = 0;
- dreq->max_count = 0;
- list_for_each_entry(req, &reqs, wb_list)
- dreq->max_count += req->wb_bytes;
- 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;
- list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
- /* Bump the transmission count */
- req->wb_nio++;
- if (!nfs_pageio_add_request(&desc, req)) {
- nfs_list_move_request(req, &failed);
- spin_lock(&cinfo.inode->i_lock);
- dreq->flags = 0;
- if (desc.pg_error < 0)
- dreq->error = desc.pg_error;
- else
- dreq->error = -EIO;
- spin_unlock(&cinfo.inode->i_lock);
- }
- nfs_release_request(req);
- }
- nfs_pageio_complete(&desc);
- while (!list_empty(&failed)) {
- req = nfs_list_entry(failed.next);
- nfs_list_remove_request(req);
- nfs_unlock_and_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->max_count = 0;
- dreq->count = 0;
- 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 && !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 /* Error or match */
- 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_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)) {
- 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;
- trace_nfs_direct_write_reschedule_io(dreq);
- spin_lock(&dreq->lock);
- if (dreq->error == 0) {
- dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
- /* fake unstable write to let common nfs resend pages */
- hdr->verf.committed = NFS_UNSTABLE;
- hdr->good_bytes = hdr->args.offset + hdr->args.count -
- hdr->io_start;
- }
- spin_unlock(&dreq->lock);
- }
- 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;
- ssize_t result = 0;
- size_t requested_bytes = 0;
- size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
- 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_create_request(dreq->ctx, pagevec[i],
- pgbase, 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;
- }
- nfs_lock_request(req);
- req->wb_index = pos >> PAGE_SHIFT;
- req->wb_offset = pos & ~PAGE_MASK;
- if (!nfs_pageio_add_request(&desc, req)) {
- result = desc.pg_error;
- nfs_unlock_and_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_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);
- }
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