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linux/fs/nfs/direct.c
Jeff Layton be7e985804 nfs: fix page dirtying in NFS DIO read codepath
The NFS DIO code will dirty pages that catch read responses in order to
handle the case where someone is doing DIO reads into an mmapped buffer.
The existing code doesn't really do the right thing though since it
doesn't take into account the case where we might be attempting to read
past the EOF.

Fix the logic in that code to only dirty pages that ended up receiving
data from the read. Note too that it really doesn't matter if
NFS_IOHDR_ERROR is set or not. All that matters is if the page was
altered by the read.

Cc: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-12 12:56:19 -05:00

1030 lines
28 KiB
C

/*
* 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);
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);
}