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-rw-r--r--fs/nfs/direct.c1030
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diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
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+/*
+ * 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 <asm/uaccess.h>
+#include <linux/atomic.h>
+
+#include "internal.h"
+#include "iostat.h"
+#include "pnfs.h"
+
+#define NFSDBG_FACILITY NFSDBG_VFS
+
+static struct kmem_cache *nfs_direct_cachep;
+
+/*
+ * This represents a set of asynchronous requests that we're waiting on
+ */
+struct nfs_direct_req {
+ struct kref kref; /* release manager */
+
+ /* I/O parameters */
+ struct nfs_open_context *ctx; /* file open context info */
+ struct nfs_lock_context *l_ctx; /* Lock context info */
+ struct kiocb * iocb; /* controlling i/o request */
+ struct inode * inode; /* target file of i/o */
+
+ /* completion state */
+ atomic_t io_count; /* i/os we're waiting for */
+ spinlock_t lock; /* protect completion state */
+ ssize_t count, /* bytes actually processed */
+ bytes_left, /* bytes left to be sent */
+ error; /* any reported error */
+ struct completion completion; /* wait for i/o completion */
+
+ /* commit state */
+ struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */
+ struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */
+ struct work_struct work;
+ int flags;
+#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
+#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
+ struct nfs_writeverf verf; /* unstable write verifier */
+};
+
+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, struct inode *inode);
+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);
+}
+
+/**
+ * nfs_direct_IO - NFS address space operation for direct I/O
+ * @rw: direction (read or write)
+ * @iocb: target I/O control block
+ * @iov: array of vectors that define I/O buffer
+ * @pos: offset in file to begin the operation
+ * @nr_segs: size of iovec array
+ *
+ * The presence of this routine in the address space ops vector means
+ * the NFS client supports direct I/O. However, for most direct IO, we
+ * shunt off direct read and write requests before the VFS gets them,
+ * so this method is only ever called for swap.
+ */
+ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
+{
+#ifndef CONFIG_NFS_SWAP
+ dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
+ iocb->ki_filp->f_path.dentry->d_name.name,
+ (long long) pos, nr_segs);
+
+ return -EINVAL;
+#else
+ VM_BUG_ON(iocb->ki_left != PAGE_SIZE);
+ VM_BUG_ON(iocb->ki_nbytes != PAGE_SIZE);
+
+ if (rw == READ || rw == KERNEL_READ)
+ return nfs_file_direct_read(iocb, iov, nr_segs, pos,
+ rw == READ ? true : false);
+ return nfs_file_direct_write(iocb, iov, nr_segs, pos,
+ rw == WRITE ? true : false);
+#endif /* CONFIG_NFS_SWAP */
+}
+
+static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
+{
+ unsigned int i;
+ for (i = 0; i < npages; i++)
+ page_cache_release(pages[i]);
+}
+
+void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
+ struct nfs_direct_req *dreq)
+{
+ cinfo->lock = &dreq->lock;
+ 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);
+ 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);
+
+ nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo);
+ 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->error;
+ if (!result)
+ result = dreq->count;
+
+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)
+{
+ if (dreq->iocb) {
+ long res = (long) dreq->error;
+ if (!res)
+ res = (long) dreq->count;
+ aio_complete(dreq->iocb, res, 0);
+ }
+ complete_all(&dreq->completion);
+
+ nfs_direct_req_release(dreq);
+}
+
+static void nfs_direct_readpage_release(struct nfs_page *req)
+{
+ dprintk("NFS: direct read done (%s/%lld %d@%lld)\n",
+ req->wb_context->dentry->d_inode->i_sb->s_id,
+ (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
+ req->wb_bytes,
+ (long long)req_offset(req));
+ nfs_release_request(req);
+}
+
+static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
+{
+ unsigned long bytes = 0;
+ struct nfs_direct_req *dreq = hdr->dreq;
+
+ if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
+ goto out_put;
+
+ spin_lock(&dreq->lock);
+ if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
+ dreq->error = hdr->error;
+ else
+ dreq->count += hdr->good_bytes;
+ 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)
+ set_page_dirty(page);
+ bytes += req->wb_bytes;
+ nfs_list_remove_request(req);
+ nfs_direct_readpage_release(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)
+{
+ 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_segment(struct nfs_pageio_descriptor *desc,
+ const struct iovec *iov,
+ loff_t pos, bool uio)
+{
+ struct nfs_direct_req *dreq = desc->pg_dreq;
+ struct nfs_open_context *ctx = dreq->ctx;
+ struct inode *inode = ctx->dentry->d_inode;
+ unsigned long user_addr = (unsigned long)iov->iov_base;
+ size_t count = iov->iov_len;
+ size_t rsize = NFS_SERVER(inode)->rsize;
+ unsigned int pgbase;
+ int result;
+ ssize_t started = 0;
+ struct page **pagevec = NULL;
+ unsigned int npages;
+
+ do {
+ size_t bytes;
+ int i;
+
+ pgbase = user_addr & ~PAGE_MASK;
+ bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
+
+ result = -ENOMEM;
+ npages = nfs_page_array_len(pgbase, bytes);
+ if (!pagevec)
+ pagevec = kmalloc(npages * sizeof(struct page *),
+ GFP_KERNEL);
+ if (!pagevec)
+ break;
+ if (uio) {
+ down_read(&current->mm->mmap_sem);
+ result = get_user_pages(current, current->mm, user_addr,
+ npages, 1, 0, pagevec, NULL);
+ up_read(&current->mm->mmap_sem);
+ if (result < 0)
+ break;
+ } else {
+ WARN_ON(npages != 1);
+ result = get_kernel_page(user_addr, 1, pagevec);
+ if (WARN_ON(result != 1))
+ break;
+ }
+
+ if ((unsigned)result < npages) {
+ bytes = result * PAGE_SIZE;
+ if (bytes <= pgbase) {
+ nfs_direct_release_pages(pagevec, result);
+ break;
+ }
+ bytes -= pgbase;
+ npages = result;
+ }
+
+ 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, dreq->inode,
+ 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;
+ started += req_len;
+ user_addr += req_len;
+ pos += req_len;
+ count -= req_len;
+ dreq->bytes_left -= req_len;
+ }
+ /* The nfs_page now hold references to these pages */
+ nfs_direct_release_pages(pagevec, npages);
+ } while (count != 0 && result >= 0);
+
+ kfree(pagevec);
+
+ if (started)
+ return started;
+ return result < 0 ? (ssize_t) result : -EFAULT;
+}
+
+static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
+ const struct iovec *iov,
+ unsigned long nr_segs,
+ loff_t pos, bool uio)
+{
+ struct nfs_pageio_descriptor desc;
+ ssize_t result = -EINVAL;
+ size_t requested_bytes = 0;
+ unsigned long seg;
+
+ NFS_PROTO(dreq->inode)->read_pageio_init(&desc, dreq->inode,
+ &nfs_direct_read_completion_ops);
+ get_dreq(dreq);
+ desc.pg_dreq = dreq;
+
+ for (seg = 0; seg < nr_segs; seg++) {
+ const struct iovec *vec = &iov[seg];
+ result = nfs_direct_read_schedule_segment(&desc, vec, pos, uio);
+ if (result < 0)
+ break;
+ requested_bytes += result;
+ if ((size_t)result < vec->iov_len)
+ break;
+ pos += vec->iov_len;
+ }
+
+ nfs_pageio_complete(&desc);
+
+ /*
+ * If no bytes were started, return the error, and let the
+ * generic layer handle the completion.
+ */
+ if (requested_bytes == 0) {
+ nfs_direct_req_release(dreq);
+ return result < 0 ? result : -EIO;
+ }
+
+ if (put_dreq(dreq))
+ nfs_direct_complete(dreq);
+ return 0;
+}
+
+static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
+ unsigned long nr_segs, loff_t pos, bool uio)
+{
+ ssize_t result = -ENOMEM;
+ struct inode *inode = iocb->ki_filp->f_mapping->host;
+ struct nfs_direct_req *dreq;
+ struct nfs_lock_context *l_ctx;
+
+ dreq = nfs_direct_req_alloc();
+ if (dreq == NULL)
+ goto out;
+
+ dreq->inode = inode;
+ dreq->bytes_left = iov_length(iov, nr_segs);
+ 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);
+ goto out_release;
+ }
+ dreq->l_ctx = l_ctx;
+ if (!is_sync_kiocb(iocb))
+ dreq->iocb = iocb;
+
+ NFS_I(inode)->read_io += iov_length(iov, nr_segs);
+ result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio);
+ if (!result)
+ result = nfs_direct_wait(dreq);
+out_release:
+ nfs_direct_req_release(dreq);
+out:
+ return result;
+}
+
+static void nfs_inode_dio_write_done(struct inode *inode)
+{
+ nfs_zap_mapping(inode, inode->i_mapping);
+ inode_dio_done(inode);
+}
+
+#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
+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);
+ pnfs_recover_commit_reqs(dreq->inode, &reqs, &cinfo);
+ spin_lock(cinfo.lock);
+ nfs_scan_commit_list(&cinfo.mds->list, &reqs, &cinfo, 0);
+ spin_unlock(cinfo.lock);
+
+ dreq->count = 0;
+ get_dreq(dreq);
+
+ NFS_PROTO(dreq->inode)->write_pageio_init(&desc, dreq->inode, FLUSH_STABLE,
+ &nfs_direct_write_completion_ops);
+ desc.pg_dreq = dreq;
+
+ list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
+ if (!nfs_pageio_add_request(&desc, req)) {
+ nfs_list_remove_request(req);
+ nfs_list_add_request(req, &failed);
+ spin_lock(cinfo.lock);
+ dreq->flags = 0;
+ dreq->error = -EIO;
+ spin_unlock(cinfo.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, dreq->inode);
+}
+
+static void nfs_direct_commit_complete(struct nfs_commit_data *data)
+{
+ struct nfs_direct_req *dreq = data->dreq;
+ struct nfs_commit_info cinfo;
+ struct nfs_page *req;
+ int status = data->task.tk_status;
+
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+ if (status < 0) {
+ dprintk("NFS: %5u commit failed with error %d.\n",
+ data->task.tk_pid, status);
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
+ dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ }
+
+ dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
+ while (!list_empty(&data->pages)) {
+ req = nfs_list_entry(data->pages.next);
+ nfs_list_remove_request(req);
+ if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
+ /* Note the rewrite will go through mds */
+ nfs_mark_request_commit(req, NULL, &cinfo);
+ } else
+ nfs_release_request(req);
+ nfs_unlock_and_release_request(req);
+ }
+
+ if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
+ nfs_direct_write_complete(dreq, data->inode);
+}
+
+static void nfs_direct_error_cleanup(struct nfs_inode *nfsi)
+{
+ /* There is no lock to clear */
+}
+
+static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
+ .completion = nfs_direct_commit_complete,
+ .error_cleanup = nfs_direct_error_cleanup,
+};
+
+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_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_inode_dio_write_done(dreq->inode);
+ nfs_direct_complete(dreq);
+ }
+}
+
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
+{
+ schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
+}
+
+#else
+static void nfs_direct_write_schedule_work(struct work_struct *work)
+{
+}
+
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
+{
+ nfs_inode_dio_write_done(inode);
+ nfs_direct_complete(dreq);
+}
+#endif
+
+/*
+ * 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_segment(struct nfs_pageio_descriptor *desc,
+ const struct iovec *iov,
+ loff_t pos, bool uio)
+{
+ struct nfs_direct_req *dreq = desc->pg_dreq;
+ struct nfs_open_context *ctx = dreq->ctx;
+ struct inode *inode = ctx->dentry->d_inode;
+ unsigned long user_addr = (unsigned long)iov->iov_base;
+ size_t count = iov->iov_len;
+ size_t wsize = NFS_SERVER(inode)->wsize;
+ unsigned int pgbase;
+ int result;
+ ssize_t started = 0;
+ struct page **pagevec = NULL;
+ unsigned int npages;
+
+ do {
+ size_t bytes;
+ int i;
+
+ pgbase = user_addr & ~PAGE_MASK;
+ bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
+
+ result = -ENOMEM;
+ npages = nfs_page_array_len(pgbase, bytes);
+ if (!pagevec)
+ pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
+ if (!pagevec)
+ break;
+
+ if (uio) {
+ down_read(&current->mm->mmap_sem);
+ result = get_user_pages(current, current->mm, user_addr,
+ npages, 0, 0, pagevec, NULL);
+ up_read(&current->mm->mmap_sem);
+ if (result < 0)
+ break;
+ } else {
+ WARN_ON(npages != 1);
+ result = get_kernel_page(user_addr, 0, pagevec);
+ if (WARN_ON(result != 1))
+ break;
+ }
+
+ if ((unsigned)result < npages) {
+ bytes = result * PAGE_SIZE;
+ if (bytes <= pgbase) {
+ nfs_direct_release_pages(pagevec, result);
+ break;
+ }
+ bytes -= pgbase;
+ npages = result;
+ }
+
+ 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, dreq->inode,
+ pagevec[i],
+ pgbase, req_len);
+ if (IS_ERR(req)) {
+ result = PTR_ERR(req);
+ 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;
+ started += req_len;
+ user_addr += req_len;
+ pos += req_len;
+ count -= req_len;
+ dreq->bytes_left -= req_len;
+ }
+ /* The nfs_page now hold references to these pages */
+ nfs_direct_release_pages(pagevec, npages);
+ } while (count != 0 && result >= 0);
+
+ kfree(pagevec);
+
+ if (started)
+ return started;
+ return result < 0 ? (ssize_t) result : -EFAULT;
+}
+
+static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
+{
+ struct nfs_direct_req *dreq = hdr->dreq;
+ struct nfs_commit_info cinfo;
+ int bit = -1;
+ struct nfs_page *req = nfs_list_entry(hdr->pages.next);
+
+ if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
+ goto out_put;
+
+ nfs_init_cinfo_from_dreq(&cinfo, dreq);
+
+ spin_lock(&dreq->lock);
+
+ if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
+ dreq->flags = 0;
+ dreq->error = hdr->error;
+ }
+ if (dreq->error != 0)
+ bit = NFS_IOHDR_ERROR;
+ else {
+ dreq->count += hdr->good_bytes;
+ if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ bit = NFS_IOHDR_NEED_RESCHED;
+ } else if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
+ if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
+ bit = NFS_IOHDR_NEED_RESCHED;
+ else if (dreq->flags == 0) {
+ memcpy(&dreq->verf, hdr->verf,
+ sizeof(dreq->verf));
+ bit = NFS_IOHDR_NEED_COMMIT;
+ dreq->flags = NFS_ODIRECT_DO_COMMIT;
+ } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
+ if (memcmp(&dreq->verf, hdr->verf, sizeof(dreq->verf))) {
+ dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+ bit = NFS_IOHDR_NEED_RESCHED;
+ } else
+ bit = NFS_IOHDR_NEED_COMMIT;
+ }
+ }
+ }
+ spin_unlock(&dreq->lock);
+
+ while (!list_empty(&hdr->pages)) {
+ req = nfs_list_entry(hdr->pages.next);
+ nfs_list_remove_request(req);
+ switch (bit) {
+ case NFS_IOHDR_NEED_RESCHED:
+ case NFS_IOHDR_NEED_COMMIT:
+ kref_get(&req->wb_kref);
+ nfs_mark_request_commit(req, hdr->lseg, &cinfo);
+ }
+ nfs_unlock_and_release_request(req);
+ }
+
+out_put:
+ if (put_dreq(dreq))
+ nfs_direct_write_complete(dreq, hdr->inode);
+ hdr->release(hdr);
+}
+
+static void nfs_write_sync_pgio_error(struct list_head *head)
+{
+ 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 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,
+};
+
+static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
+ const struct iovec *iov,
+ unsigned long nr_segs,
+ loff_t pos, bool uio)
+{
+ struct nfs_pageio_descriptor desc;
+ struct inode *inode = dreq->inode;
+ ssize_t result = 0;
+ size_t requested_bytes = 0;
+ unsigned long seg;
+
+ NFS_PROTO(inode)->write_pageio_init(&desc, inode, FLUSH_COND_STABLE,
+ &nfs_direct_write_completion_ops);
+ desc.pg_dreq = dreq;
+ get_dreq(dreq);
+ atomic_inc(&inode->i_dio_count);
+
+ NFS_I(dreq->inode)->write_io += iov_length(iov, nr_segs);
+ for (seg = 0; seg < nr_segs; seg++) {
+ const struct iovec *vec = &iov[seg];
+ result = nfs_direct_write_schedule_segment(&desc, vec, pos, uio);
+ if (result < 0)
+ break;
+ requested_bytes += result;
+ if ((size_t)result < vec->iov_len)
+ break;
+ pos += vec->iov_len;
+ }
+ 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_done(inode);
+ nfs_direct_req_release(dreq);
+ return result < 0 ? result : -EIO;
+ }
+
+ if (put_dreq(dreq))
+ nfs_direct_write_complete(dreq, dreq->inode);
+ return 0;
+}
+
+static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
+ unsigned long nr_segs, loff_t pos,
+ size_t count, bool uio)
+{
+ ssize_t result = -ENOMEM;
+ struct inode *inode = iocb->ki_filp->f_mapping->host;
+ struct nfs_direct_req *dreq;
+ struct nfs_lock_context *l_ctx;
+
+ dreq = nfs_direct_req_alloc();
+ if (!dreq)
+ goto out;
+
+ dreq->inode = inode;
+ dreq->bytes_left = count;
+ 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);
+ goto out_release;
+ }
+ dreq->l_ctx = l_ctx;
+ if (!is_sync_kiocb(iocb))
+ dreq->iocb = iocb;
+
+ result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, uio);
+ if (!result)
+ result = nfs_direct_wait(dreq);
+out_release:
+ nfs_direct_req_release(dreq);
+out:
+ return result;
+}
+
+/**
+ * nfs_file_direct_read - file direct read operation for NFS files
+ * @iocb: target I/O control block
+ * @iov: vector of user buffers into which to read data
+ * @nr_segs: size of iov vector
+ * @pos: byte offset in file where reading starts
+ *
+ * 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, const struct iovec *iov,
+ unsigned long nr_segs, loff_t pos, bool uio)
+{
+ ssize_t retval = -EINVAL;
+ struct file *file = iocb->ki_filp;
+ struct address_space *mapping = file->f_mapping;
+ size_t count;
+
+ count = iov_length(iov, nr_segs);
+ nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
+
+ dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
+ file->f_path.dentry->d_parent->d_name.name,
+ file->f_path.dentry->d_name.name,
+ count, (long long) pos);
+
+ retval = 0;
+ if (!count)
+ goto out;
+
+ retval = nfs_sync_mapping(mapping);
+ if (retval)
+ goto out;
+
+ task_io_account_read(count);
+
+ retval = nfs_direct_read(iocb, iov, nr_segs, pos, uio);
+ if (retval > 0)
+ iocb->ki_pos = pos + retval;
+
+out:
+ return retval;
+}
+
+/**
+ * nfs_file_direct_write - file direct write operation for NFS files
+ * @iocb: target I/O control block
+ * @iov: vector of user buffers from which to write data
+ * @nr_segs: size of iov vector
+ * @pos: byte offset in file where writing starts
+ *
+ * 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, const struct iovec *iov,
+ unsigned long nr_segs, loff_t pos, bool uio)
+{
+ ssize_t retval = -EINVAL;
+ struct file *file = iocb->ki_filp;
+ struct address_space *mapping = file->f_mapping;
+ size_t count;
+
+ count = iov_length(iov, nr_segs);
+ nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
+
+ dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
+ file->f_path.dentry->d_parent->d_name.name,
+ file->f_path.dentry->d_name.name,
+ count, (long long) pos);
+
+ retval = generic_write_checks(file, &pos, &count, 0);
+ if (retval)
+ goto out;
+
+ retval = -EINVAL;
+ if ((ssize_t) count < 0)
+ goto out;
+ retval = 0;
+ if (!count)
+ goto out;
+
+ retval = nfs_sync_mapping(mapping);
+ if (retval)
+ goto out;
+
+ task_io_account_write(count);
+
+ retval = nfs_direct_write(iocb, iov, nr_segs, pos, count, uio);
+ if (retval > 0) {
+ struct inode *inode = mapping->host;
+
+ iocb->ki_pos = pos + retval;
+ spin_lock(&inode->i_lock);
+ if (i_size_read(inode) < iocb->ki_pos)
+ i_size_write(inode, iocb->ki_pos);
+ spin_unlock(&inode->i_lock);
+ }
+out:
+ return retval;
+}
+
+/**
+ * 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);
+}
generated by cgit v1.3.1 (git 2.54.0) at 2026-08-15 13:07:34 +0000