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DEFINITIONS
This source file includes following definitions.
- get_dreq
- put_dreq
- nfs_direct_IO
- nfs_direct_dirty_pages
- nfs_direct_release_pages
- nfs_direct_req_alloc
- nfs_direct_req_free
- nfs_direct_req_release
- nfs_direct_wait
- nfs_direct_complete
- nfs_direct_read_result
- nfs_direct_read_release
- nfs_direct_read_schedule_segment
- nfs_direct_read_schedule_iovec
- nfs_direct_read
- nfs_direct_free_writedata
- nfs_direct_write_reschedule
- nfs_direct_commit_result
- nfs_direct_commit_release
- nfs_direct_commit_schedule
- nfs_direct_write_complete
- nfs_alloc_commit_data
- nfs_alloc_commit_data
- nfs_direct_write_complete
- nfs_direct_write_result
- nfs_direct_write_release
- nfs_direct_write_schedule_segment
- nfs_direct_write_schedule_iovec
- nfs_direct_write
- nfs_file_direct_read
- nfs_file_direct_write
- nfs_init_directcache
- nfs_destroy_directcache
/*
* 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/nfs_fs.h>
#include <linux/nfs_page.h>
#include <linux/sunrpc/clnt.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include "internal.h"
#include "iostat.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 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 */
error; /* any reported error */
struct completion completion; /* wait for i/o completion */
/* commit state */
struct list_head rewrite_list; /* saved nfs_write_data structs */
struct nfs_write_data * commit_data; /* special write_data for commits */
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 void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
static const struct rpc_call_ops nfs_write_direct_ops;
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, we shunt off direct
* read and write requests before the VFS gets them, so this method
* should never be called.
*/
ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
{
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;
}
static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
{
unsigned int npages;
unsigned int i;
if (count == 0)
return;
pages += (pgbase >> PAGE_SHIFT);
npages = (count + (pgbase & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
for (i = 0; i < npages; i++) {
struct page *page = pages[i];
if (!PageCompound(page))
set_page_dirty(page);
}
}
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]);
}
static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
{
struct nfs_direct_req *dreq;
dreq = kmem_cache_alloc(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->rewrite_list);
dreq->iocb = NULL;
dreq->ctx = NULL;
spin_lock_init(&dreq->lock);
atomic_set(&dreq->io_count, 0);
dreq->count = 0;
dreq->error = 0;
dreq->flags = 0;
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->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);
}
/*
* 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);
}
/*
* We must hold a reference to all the pages in this direct read request
* until the RPCs complete. This could be long *after* we are woken up in
* nfs_direct_wait (for instance, if someone hits ^C on a slow server).
*/
static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
{
struct nfs_read_data *data = calldata;
nfs_readpage_result(task, data);
}
static void nfs_direct_read_release(void *calldata)
{
struct nfs_read_data *data = calldata;
struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
int status = data->task.tk_status;
spin_lock(&dreq->lock);
if (unlikely(status < 0)) {
dreq->error = status;
spin_unlock(&dreq->lock);
} else {
dreq->count += data->res.count;
spin_unlock(&dreq->lock);
nfs_direct_dirty_pages(data->pagevec,
data->args.pgbase,
data->res.count);
}
nfs_direct_release_pages(data->pagevec, data->npages);
if (put_dreq(dreq))
nfs_direct_complete(dreq);
nfs_readdata_release(calldata);
}
static const struct rpc_call_ops nfs_read_direct_ops = {
.rpc_call_done = nfs_direct_read_result,
.rpc_release = nfs_direct_read_release,
};
/*
* 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_direct_req *dreq,
const struct iovec *iov,
loff_t pos)
{
struct nfs_open_context *ctx = dreq->ctx;
struct inode *inode = ctx->path.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;
struct rpc_task *task;
struct rpc_message msg = {
.rpc_cred = ctx->cred,
};
struct rpc_task_setup task_setup_data = {
.rpc_client = NFS_CLIENT(inode),
.rpc_message = &msg,
.callback_ops = &nfs_read_direct_ops,
.workqueue = nfsiod_workqueue,
.flags = RPC_TASK_ASYNC,
};
unsigned int pgbase;
int result;
ssize_t started = 0;
do {
struct nfs_read_data *data;
size_t bytes;
pgbase = user_addr & ~PAGE_MASK;
bytes = min(rsize,count);
result = -ENOMEM;
data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
if (unlikely(!data))
break;
down_read(¤t->mm->mmap_sem);
result = get_user_pages(current, current->mm, user_addr,
data->npages, 1, 0, data->pagevec, NULL);
up_read(¤t->mm->mmap_sem);
if (result < 0) {
nfs_readdata_release(data);
break;
}
if ((unsigned)result < data->npages) {
bytes = result * PAGE_SIZE;
if (bytes <= pgbase) {
nfs_direct_release_pages(data->pagevec, result);
nfs_readdata_release(data);
break;
}
bytes -= pgbase;
data->npages = result;
}
get_dreq(dreq);
data->req = (struct nfs_page *) dreq;
data->inode = inode;
data->cred = msg.rpc_cred;
data->args.fh = NFS_FH(inode);
data->args.context = get_nfs_open_context(ctx);
data->args.offset = pos;
data->args.pgbase = pgbase;
data->args.pages = data->pagevec;
data->args.count = bytes;
data->res.fattr = &data->fattr;
data->res.eof = 0;
data->res.count = bytes;
msg.rpc_argp = &data->args;
msg.rpc_resp = &data->res;
task_setup_data.task = &data->task;
task_setup_data.callback_data = data;
NFS_PROTO(inode)->read_setup(data, &msg);
task = rpc_run_task(&task_setup_data);
if (IS_ERR(task))
break;
rpc_put_task(task);
dprintk("NFS: %5u initiated direct read call "
"(req %s/%Ld, %zu bytes @ offset %Lu)\n",
data->task.tk_pid,
inode->i_sb->s_id,
(long long)NFS_FILEID(inode),
bytes,
(unsigned long long)data->args.offset);
started += bytes;
user_addr += bytes;
pos += bytes;
/* FIXME: Remove this unnecessary math from final patch */
pgbase += bytes;
pgbase &= ~PAGE_MASK;
BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
count -= bytes;
} while (count != 0);
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)
{
ssize_t result = -EINVAL;
size_t requested_bytes = 0;
unsigned long seg;
get_dreq(dreq);
for (seg = 0; seg < nr_segs; seg++) {
const struct iovec *vec = &iov[seg];
result = nfs_direct_read_schedule_segment(dreq, vec, pos);
if (result < 0)
break;
requested_bytes += result;
if ((size_t)result < vec->iov_len)
break;
pos += vec->iov_len;
}
if (put_dreq(dreq))
nfs_direct_complete(dreq);
if (requested_bytes != 0)
return 0;
if (result < 0)
return result;
return -EIO;
}
static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
ssize_t result = 0;
struct inode *inode = iocb->ki_filp->f_mapping->host;
struct nfs_direct_req *dreq;
dreq = nfs_direct_req_alloc();
if (!dreq)
return -ENOMEM;
dreq->inode = inode;
dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
if (!is_sync_kiocb(iocb))
dreq->iocb = iocb;
result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
if (!result)
result = nfs_direct_wait(dreq);
nfs_direct_req_release(dreq);
return result;
}
static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
{
while (!list_empty(&dreq->rewrite_list)) {
struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
list_del(&data->pages);
nfs_direct_release_pages(data->pagevec, data->npages);
nfs_writedata_release(data);
}
}
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
{
struct inode *inode = dreq->inode;
struct list_head *p;
struct nfs_write_data *data;
struct rpc_task *task;
struct rpc_message msg = {
.rpc_cred = dreq->ctx->cred,
};
struct rpc_task_setup task_setup_data = {
.rpc_client = NFS_CLIENT(inode),
.callback_ops = &nfs_write_direct_ops,
.workqueue = nfsiod_workqueue,
.flags = RPC_TASK_ASYNC,
};
dreq->count = 0;
get_dreq(dreq);
list_for_each(p, &dreq->rewrite_list) {
data = list_entry(p, struct nfs_write_data, pages);
get_dreq(dreq);
/* Use stable writes */
data->args.stable = NFS_FILE_SYNC;
/*
* Reset data->res.
*/
nfs_fattr_init(&data->fattr);
data->res.count = data->args.count;
memset(&data->verf, 0, sizeof(data->verf));
/*
* Reuse data->task; data->args should not have changed
* since the original request was sent.
*/
task_setup_data.task = &data->task;
task_setup_data.callback_data = data;
msg.rpc_argp = &data->args;
msg.rpc_resp = &data->res;
NFS_PROTO(inode)->write_setup(data, &msg);
/*
* We're called via an RPC callback, so BKL is already held.
*/
task = rpc_run_task(&task_setup_data);
if (!IS_ERR(task))
rpc_put_task(task);
dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
data->task.tk_pid,
inode->i_sb->s_id,
(long long)NFS_FILEID(inode),
data->args.count,
(unsigned long long)data->args.offset);
}
if (put_dreq(dreq))
nfs_direct_write_complete(dreq, inode);
}
static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
{
struct nfs_write_data *data = calldata;
/* Call the NFS version-specific code */
NFS_PROTO(data->inode)->commit_done(task, data);
}
static void nfs_direct_commit_release(void *calldata)
{
struct nfs_write_data *data = calldata;
struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
int status = data->task.tk_status;
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);
nfs_direct_write_complete(dreq, data->inode);
nfs_commitdata_release(calldata);
}
static const struct rpc_call_ops nfs_commit_direct_ops = {
.rpc_call_done = nfs_direct_commit_result,
.rpc_release = nfs_direct_commit_release,
};
static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
{
struct nfs_write_data *data = dreq->commit_data;
struct rpc_task *task;
struct rpc_message msg = {
.rpc_argp = &data->args,
.rpc_resp = &data->res,
.rpc_cred = dreq->ctx->cred,
};
struct rpc_task_setup task_setup_data = {
.task = &data->task,
.rpc_client = NFS_CLIENT(dreq->inode),
.rpc_message = &msg,
.callback_ops = &nfs_commit_direct_ops,
.callback_data = data,
.workqueue = nfsiod_workqueue,
.flags = RPC_TASK_ASYNC,
};
data->inode = dreq->inode;
data->cred = msg.rpc_cred;
data->args.fh = NFS_FH(data->inode);
data->args.offset = 0;
data->args.count = 0;
data->args.context = get_nfs_open_context(dreq->ctx);
data->res.count = 0;
data->res.fattr = &data->fattr;
data->res.verf = &data->verf;
NFS_PROTO(data->inode)->commit_setup(data, &msg);
/* Note: task.tk_ops->rpc_release will free dreq->commit_data */
dreq->commit_data = NULL;
dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
task = rpc_run_task(&task_setup_data);
if (!IS_ERR(task))
rpc_put_task(task);
}
static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
{
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:
if (dreq->commit_data != NULL)
nfs_commit_free(dreq->commit_data);
nfs_direct_free_writedata(dreq);
nfs_zap_mapping(inode, inode->i_mapping);
nfs_direct_complete(dreq);
}
}
static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
{
dreq->commit_data = nfs_commitdata_alloc();
if (dreq->commit_data != NULL)
dreq->commit_data->req = (struct nfs_page *) dreq;
}
#else
static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
{
dreq->commit_data = NULL;
}
static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
{
nfs_direct_free_writedata(dreq);
nfs_zap_mapping(inode, inode->i_mapping);
nfs_direct_complete(dreq);
}
#endif
static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
{
struct nfs_write_data *data = calldata;
if (nfs_writeback_done(task, data) != 0)
return;
}
/*
* NB: Return the value of the first error return code. Subsequent
* errors after the first one are ignored.
*/
static void nfs_direct_write_release(void *calldata)
{
struct nfs_write_data *data = calldata;
struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
int status = data->task.tk_status;
spin_lock(&dreq->lock);
if (unlikely(status < 0)) {
/* An error has occurred, so we should not commit */
dreq->flags = 0;
dreq->error = status;
}
if (unlikely(dreq->error != 0))
goto out_unlock;
dreq->count += data->res.count;
if (data->res.verf->committed != NFS_FILE_SYNC) {
switch (dreq->flags) {
case 0:
memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
dreq->flags = NFS_ODIRECT_DO_COMMIT;
break;
case NFS_ODIRECT_DO_COMMIT:
if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
}
}
}
out_unlock:
spin_unlock(&dreq->lock);
if (put_dreq(dreq))
nfs_direct_write_complete(dreq, data->inode);
}
static const struct rpc_call_ops nfs_write_direct_ops = {
.rpc_call_done = nfs_direct_write_result,
.rpc_release = nfs_direct_write_release,
};
/*
* 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_direct_req *dreq,
const struct iovec *iov,
loff_t pos, int sync)
{
struct nfs_open_context *ctx = dreq->ctx;
struct inode *inode = ctx->path.dentry->d_inode;
unsigned long user_addr = (unsigned long)iov->iov_base;
size_t count = iov->iov_len;
struct rpc_task *task;
struct rpc_message msg = {
.rpc_cred = ctx->cred,
};
struct rpc_task_setup task_setup_data = {
.rpc_client = NFS_CLIENT(inode),
.rpc_message = &msg,
.callback_ops = &nfs_write_direct_ops,
.workqueue = nfsiod_workqueue,
.flags = RPC_TASK_ASYNC,
};
size_t wsize = NFS_SERVER(inode)->wsize;
unsigned int pgbase;
int result;
ssize_t started = 0;
do {
struct nfs_write_data *data;
size_t bytes;
pgbase = user_addr & ~PAGE_MASK;
bytes = min(wsize,count);
result = -ENOMEM;
data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
if (unlikely(!data))
break;
down_read(¤t->mm->mmap_sem);
result = get_user_pages(current, current->mm, user_addr,
data->npages, 0, 0, data->pagevec, NULL);
up_read(¤t->mm->mmap_sem);
if (result < 0) {
nfs_writedata_release(data);
break;
}
if ((unsigned)result < data->npages) {
bytes = result * PAGE_SIZE;
if (bytes <= pgbase) {
nfs_direct_release_pages(data->pagevec, result);
nfs_writedata_release(data);
break;
}
bytes -= pgbase;
data->npages = result;
}
get_dreq(dreq);
list_move_tail(&data->pages, &dreq->rewrite_list);
data->req = (struct nfs_page *) dreq;
data->inode = inode;
data->cred = msg.rpc_cred;
data->args.fh = NFS_FH(inode);
data->args.context = get_nfs_open_context(ctx);
data->args.offset = pos;
data->args.pgbase = pgbase;
data->args.pages = data->pagevec;
data->args.count = bytes;
data->args.stable = sync;
data->res.fattr = &data->fattr;
data->res.count = bytes;
data->res.verf = &data->verf;
task_setup_data.task = &data->task;
task_setup_data.callback_data = data;
msg.rpc_argp = &data->args;
msg.rpc_resp = &data->res;
NFS_PROTO(inode)->write_setup(data, &msg);
task = rpc_run_task(&task_setup_data);
if (IS_ERR(task))
break;
rpc_put_task(task);
dprintk("NFS: %5u initiated direct write call "
"(req %s/%Ld, %zu bytes @ offset %Lu)\n",
data->task.tk_pid,
inode->i_sb->s_id,
(long long)NFS_FILEID(inode),
bytes,
(unsigned long long)data->args.offset);
started += bytes;
user_addr += bytes;
pos += bytes;
/* FIXME: Remove this useless math from the final patch */
pgbase += bytes;
pgbase &= ~PAGE_MASK;
BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
count -= bytes;
} while (count != 0);
if (started)
return started;
return result < 0 ? (ssize_t) result : -EFAULT;
}
static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
const struct iovec *iov,
unsigned long nr_segs,
loff_t pos, int sync)
{
ssize_t result = 0;
size_t requested_bytes = 0;
unsigned long seg;
get_dreq(dreq);
for (seg = 0; seg < nr_segs; seg++) {
const struct iovec *vec = &iov[seg];
result = nfs_direct_write_schedule_segment(dreq, vec,
pos, sync);
if (result < 0)
break;
requested_bytes += result;
if ((size_t)result < vec->iov_len)
break;
pos += vec->iov_len;
}
if (put_dreq(dreq))
nfs_direct_write_complete(dreq, dreq->inode);
if (requested_bytes != 0)
return 0;
if (result < 0)
return result;
return -EIO;
}
static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos,
size_t count)
{
ssize_t result = 0;
struct inode *inode = iocb->ki_filp->f_mapping->host;
struct nfs_direct_req *dreq;
size_t wsize = NFS_SERVER(inode)->wsize;
int sync = NFS_UNSTABLE;
dreq = nfs_direct_req_alloc();
if (!dreq)
return -ENOMEM;
nfs_alloc_commit_data(dreq);
if (dreq->commit_data == NULL || count < wsize)
sync = NFS_FILE_SYNC;
dreq->inode = inode;
dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
if (!is_sync_kiocb(iocb))
dreq->iocb = iocb;
result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
if (!result)
result = nfs_direct_wait(dreq);
nfs_direct_req_release(dreq);
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)
{
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;
retval = nfs_direct_read(iocb, iov, nr_segs, pos);
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 also avoid an unnecessary invocation of generic_osync_inode(),
* as it is fairly meaningless to sync the metadata of an NFS file.
*
* 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)
{
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;
retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
if (retval > 0)
iocb->ki_pos = pos + retval;
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);
}