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linux-next/fs/nfs/direct.c
Al Viro 85128b2be6 fix nfs O_DIRECT advancing iov_iter too much
It leaves the iterator advanced by the amount of IO it has requested
instead of the amount actually transferred.  Among other things,
that confuses the hell out of generic_file_splice_read().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-04-17 14:23:20 -04:00

1082 lines
29 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 <linux/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_mirror {
ssize_t count;
};
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 */
struct nfs_direct_mirror mirrors[NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX];
int mirror_count;
ssize_t count, /* bytes actually processed */
max_count, /* max expected count */
bytes_left, /* bytes left to be sent */
io_start, /* start of IO */
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);
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_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr)
{
int i;
ssize_t count;
WARN_ON_ONCE(dreq->count >= dreq->max_count);
if (dreq->mirror_count == 1) {
dreq->mirrors[hdr->pgio_mirror_idx].count += hdr->good_bytes;
dreq->count += hdr->good_bytes;
} else {
/* mirrored writes */
count = dreq->mirrors[hdr->pgio_mirror_idx].count;
if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) {
count = hdr->io_start + hdr->good_bytes - dreq->io_start;
dreq->mirrors[hdr->pgio_mirror_idx].count = count;
}
/* update the dreq->count by finding the minimum agreed count from all
* mirrors */
count = dreq->mirrors[0].count;
for (i = 1; i < dreq->mirror_count; i++)
count = min(count, dreq->mirrors[i].count);
dreq->count = count;
}
}
/*
* nfs_direct_select_verf - select the right verifier
* @dreq - direct request possibly spanning multiple servers
* @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs
* @commit_idx - commit bucket index for the DS
*
* returns the correct verifier to use given the role of the server
*/
static struct nfs_writeverf *
nfs_direct_select_verf(struct nfs_direct_req *dreq,
struct nfs_client *ds_clp,
int commit_idx)
{
struct nfs_writeverf *verfp = &dreq->verf;
#ifdef CONFIG_NFS_V4_1
/*
* pNFS is in use, use the DS verf except commit_through_mds is set
* for layout segment where nbuckets is zero.
*/
if (ds_clp && dreq->ds_cinfo.nbuckets > 0) {
if (commit_idx >= 0 && commit_idx < dreq->ds_cinfo.nbuckets)
verfp = &dreq->ds_cinfo.buckets[commit_idx].direct_verf;
else
WARN_ON_ONCE(1);
}
#endif
return verfp;
}
/*
* nfs_direct_set_hdr_verf - set the write/commit verifier
* @dreq - direct request possibly spanning multiple servers
* @hdr - pageio header to validate against previously seen verfs
*
* Set the server's (MDS or DS) "seen" verifier
*/
static void nfs_direct_set_hdr_verf(struct nfs_direct_req *dreq,
struct nfs_pgio_header *hdr)
{
struct nfs_writeverf *verfp;
verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx);
WARN_ON_ONCE(verfp->committed >= 0);
memcpy(verfp, &hdr->verf, sizeof(struct nfs_writeverf));
WARN_ON_ONCE(verfp->committed < 0);
}
static int nfs_direct_cmp_verf(const struct nfs_writeverf *v1,
const struct nfs_writeverf *v2)
{
return nfs_write_verifier_cmp(&v1->verifier, &v2->verifier);
}
/*
* nfs_direct_cmp_hdr_verf - compare verifier for pgio header
* @dreq - direct request possibly spanning multiple servers
* @hdr - pageio header to validate against previously seen verf
*
* set the server's "seen" verf if not initialized.
* returns result of comparison between @hdr->verf and the "seen"
* verf of the server used by @hdr (DS or MDS)
*/
static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req *dreq,
struct nfs_pgio_header *hdr)
{
struct nfs_writeverf *verfp;
verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx);
if (verfp->committed < 0) {
nfs_direct_set_hdr_verf(dreq, hdr);
return 0;
}
return nfs_direct_cmp_verf(verfp, &hdr->verf);
}
/*
* nfs_direct_cmp_commit_data_verf - compare verifier for commit data
* @dreq - direct request possibly spanning multiple servers
* @data - commit data to validate against previously seen verf
*
* returns result of comparison between @data->verf and the verf of
* the server used by @data (DS or MDS)
*/
static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq,
struct nfs_commit_data *data)
{
struct nfs_writeverf *verfp;
verfp = nfs_direct_select_verf(dreq, data->ds_clp,
data->ds_commit_index);
/* verifier not set so always fail */
if (verfp->committed < 0)
return 1;
return nfs_direct_cmp_verf(verfp, &data->verf);
}
/**
* nfs_direct_IO - NFS address space operation for direct I/O
* @iocb: target I/O control block
* @iter: I/O buffer
*
* 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(struct kiocb *iocb, struct iov_iter *iter)
{
struct inode *inode = iocb->ki_filp->f_mapping->host;
/* we only support swap file calling nfs_direct_IO */
if (!IS_SWAPFILE(inode))
return 0;
VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE);
if (iov_iter_rw(iter) == READ)
return nfs_file_direct_read(iocb, iter);
return nfs_file_direct_write(iocb, iter);
}
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 void nfs_direct_setup_mirroring(struct nfs_direct_req *dreq,
struct nfs_pageio_descriptor *pgio,
struct nfs_page *req)
{
int mirror_count = 1;
if (pgio->pg_ops->pg_get_mirror_count)
mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
dreq->mirror_count = mirror_count;
}
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);
dreq->verf.committed = NFS_INVALID_STABLE_HOW; /* not set yet */
INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
dreq->mirror_count = 1;
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->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, 0);
}
complete(&dreq->completion);
nfs_direct_req_release(dreq);
}
static void nfs_direct_readpage_release(struct nfs_page *req)
{
dprintk("NFS: direct read done (%s/%llu %d@%lld)\n",
req->wb_context->dentry->d_sb->s_id,
(unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)),
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
nfs_direct_good_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)
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_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_alloc(iter, &pagevec,
rsize, &pgbase);
if (result < 0)
break;
bytes = result;
iov_iter_advance(iter, bytes);
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], NULL,
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
*
* 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)
{
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 = -EINVAL, 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);
goto out_release;
}
dreq->l_ctx = l_ctx;
if (!is_sync_kiocb(iocb))
dreq->iocb = iocb;
nfs_start_io_direct(inode);
NFS_I(inode)->read_io += count;
requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
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_write_scan_commit_list(struct inode *inode,
struct list_head *list,
struct nfs_commit_info *cinfo)
{
spin_lock(&cinfo->inode->i_lock);
#ifdef CONFIG_NFS_V4_1
if (cinfo->ds != NULL && cinfo->ds->nwritten != 0)
NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo);
#endif
nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
spin_unlock(&cinfo->inode->i_lock);
}
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);
int i;
nfs_init_cinfo_from_dreq(&cinfo, dreq);
nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
dreq->count = 0;
dreq->verf.committed = NFS_INVALID_STABLE_HOW;
nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
for (i = 0; i < dreq->mirror_count; i++)
dreq->mirrors[i].count = 0;
get_dreq(dreq);
nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
&nfs_direct_write_completion_ops);
desc.pg_dreq = dreq;
req = nfs_list_entry(reqs.next);
nfs_direct_setup_mirroring(dreq, &desc, req);
if (desc.pg_error < 0) {
list_splice_init(&reqs, &failed);
goto out_failed;
}
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.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);
out_failed:
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)
{
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 (nfs_direct_cmp_commit_data_verf(dreq, data)) {
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, 0);
} 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);
}
static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
struct nfs_page *req)
{
struct nfs_direct_req *dreq = cinfo->dreq;
spin_lock(&dreq->lock);
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_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_zap_mapping(dreq->inode, dreq->inode->i_mapping);
nfs_direct_complete(dreq);
}
}
static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
{
schedule_work(&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;
bool request_commit = false;
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) {
nfs_direct_good_bytes(dreq, hdr);
if (nfs_write_need_commit(hdr)) {
if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
request_commit = true;
else if (dreq->flags == 0) {
nfs_direct_set_hdr_verf(dreq, hdr);
request_commit = true;
dreq->flags = NFS_ODIRECT_DO_COMMIT;
} else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
request_commit = true;
if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr))
dreq->flags =
NFS_ODIRECT_RESCHED_WRITES;
}
}
}
spin_unlock(&dreq->lock);
while (!list_empty(&hdr->pages)) {
req = nfs_list_entry(hdr->pages.next);
nfs_list_remove_request(req);
if (request_commit) {
kref_get(&req->wb_kref);
nfs_mark_request_commit(req, hdr->lseg, &cinfo,
hdr->ds_commit_idx);
}
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)
{
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;
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.count;
}
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)
{
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);
nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, 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_alloc(iter, &pagevec,
wsize, &pgbase);
if (result < 0)
break;
bytes = result;
iov_iter_advance(iter, bytes);
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], NULL,
pgbase, req_len);
if (IS_ERR(req)) {
result = PTR_ERR(req);
break;
}
nfs_direct_setup_mirroring(dreq, &desc, req);
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
*
* 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)
{
ssize_t result = -EINVAL, 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);
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);
goto out_release;
}
dreq->l_ctx = l_ctx;
if (!is_sync_kiocb(iocb))
dreq->iocb = iocb;
nfs_start_io_direct(inode);
requested = nfs_direct_write_schedule_iovec(dreq, iter, pos);
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;
}
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);
}