- 根目录:
- fs
- nfs
- direct.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_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 */
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, 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);
}
void nfs_direct_set_resched_writes(struct nfs_direct_req *dreq)
{
dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
}
EXPORT_SYMBOL_GPL(nfs_direct_set_resched_writes);
static void
nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr)
{
int i;
ssize_t 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);
}
/*
* 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 memcmp(verfp, &hdr->verf, sizeof(struct nfs_writeverf));
}
/*
* 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 memcmp(verfp, &data->verf, sizeof(struct nfs_writeverf));
}
/**
* nfs_direct_IO - NFS address space operation for direct I/O
* @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(struct kiocb *iocb, struct iov_iter *iter, loff_t pos)
{
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, pos);
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++)
page_cache_release(pages[i]);
}
void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
struct nfs_direct_req *dreq)
{
cinfo->lock = &dreq->inode->i_lock;
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->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, bool write)
{
struct inode *inode = dreq->inode;
if (dreq->iocb && write) {
loff_t pos = dreq->iocb->ki_pos + dreq->count;
spin_lock(&inode->i_lock);
if (i_size_read(inode) < pos)
i_size_write(inode, pos);
spin_unlock(&inode->i_lock);
}
if (write)
nfs_zap_mapping(inode, inode->i_mapping);
inode_dio_end(inode);
if (dreq->iocb) {
long res = (long) dreq->error;
if (!res)
res = (long) dreq->count;
dreq->iocb->ki_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/%llu %d@%lld)\n",
d_inode(req->wb_context->dentry)->i_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, false);
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, false);
return 0;
}
/**
* 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
* @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, struct iov_iter *iter,
loff_t pos)
{
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;
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) pos);
result = 0;
if (!count)
goto out;
mutex_lock(&inode->i_mutex);
result = nfs_sync_mapping(mapping);
if (result)
goto out_unlock;
task_io_account_read(count);
result = -ENOMEM;
dreq = nfs_direct_req_alloc();
if (dreq == NULL)
goto out_unlock;
dreq->inode = inode;
dreq->bytes_left = 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_I(inode)->read_io += count;
result = nfs_direct_read_schedule_iovec(dreq, iter, pos);
mutex_unlock(&inode->i_mutex);
if (!result) {
result = nfs_direct_wait(dreq);
if (result > 0)
iocb->ki_pos = pos + result;
}
nfs_direct_req_release(dreq);
return result;
out_release:
nfs_direct_req_release(dreq);
out_unlock:
mutex_unlock(&inode->i_mutex);
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->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->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;
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);
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 (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, 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_direct_complete(dreq, true);
}
}
static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
{
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->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,
};
/*
* 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);
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, dreq->inode);
return 0;
}
/**
* 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
* @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, struct iov_iter *iter)
{
ssize_t result = -EINVAL;
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);
nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES,
iov_iter_count(iter));
pos = iocb->ki_pos;
end = (pos + iov_iter_count(iter) - 1) >> PAGE_CACHE_SHIFT;
mutex_lock(&inode->i_mutex);
result = nfs_sync_mapping(mapping);
if (result)
goto out_unlock;
if (mapping->nrpages) {
result = invalidate_inode_pages2_range(mapping,
pos >> PAGE_CACHE_SHIFT, end);
if (result)
goto out_unlock;
}
task_io_account_write(iov_iter_count(iter));
result = -ENOMEM;
dreq = nfs_direct_req_alloc();
if (!dreq)
goto out_unlock;
dreq->inode = inode;
dreq->bytes_left = iov_iter_count(iter);
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;
result = nfs_direct_write_schedule_iovec(dreq, iter, pos);
if (mapping->nrpages) {
invalidate_inode_pages2_range(mapping,
pos >> PAGE_CACHE_SHIFT, end);
}
mutex_unlock(&inode->i_mutex);
if (!result) {
result = nfs_direct_wait(dreq);
if (result > 0) {
struct inode *inode = mapping->host;
iocb->ki_pos = pos + result;
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);
generic_write_sync(file, pos, result);
}
}
nfs_direct_req_release(dreq);
return result;
out_release:
nfs_direct_req_release(dreq);
out_unlock:
mutex_unlock(&inode->i_mutex);
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);
}