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write.c
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/*
* linux/fs/nfs/write.c
*
* Writing file data over NFS.
*
* We do it like this: When a (user) process wishes to write data to an
* NFS file, a write request is allocated that contains the RPC task data
* plus some info on the page to be written, and added to the inode's
* write chain. If the process writes past the end of the page, an async
* RPC call to write the page is scheduled immediately; otherwise, the call
* is delayed for a few seconds.
*
* Just like readahead, no async I/O is performed if wsize < PAGE_SIZE.
*
* Write requests are kept on the inode's writeback list. Each entry in
* that list references the page (portion) to be written. When the
* cache timeout has expired, the RPC task is woken up, and tries to
* lock the page. As soon as it manages to do so, the request is moved
* from the writeback list to the writelock list.
*
* Note: we must make sure never to confuse the inode passed in the
* write_page request with the one in page->inode. As far as I understand
* it, these are different when doing a swap-out.
*
* To understand everything that goes on here and in the NFS read code,
* one should be aware that a page is locked in exactly one of the following
* cases:
*
* - A write request is in progress.
* - A user process is in generic_file_write/nfs_update_page
* - A user process is in generic_file_read
*
* Also note that because of the way pages are invalidated in
* nfs_revalidate_inode, the following assertions hold:
*
* - If a page is dirty, there will be no read requests (a page will
* not be re-read unless invalidated by nfs_revalidate_inode).
* - If the page is not uptodate, there will be no pending write
* requests, and no process will be in nfs_update_page.
*
* FIXME: Interaction with the vmscan routines is not optimal yet.
* Either vmscan must be made nfs-savvy, or we need a different page
* reclaim concept that supports something like FS-independent
* buffer_heads with a b_ops-> field.
*
* Copyright (C) 1996, 1997, Olaf Kirch <[email protected]>
*/
#include <linux/config.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/mpage.h>
#include <linux/writeback.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs_page.h>
#include <asm/uaccess.h>
#include <linux/smp_lock.h>
#include "delegation.h"
#define NFSDBG_FACILITY NFSDBG_PAGECACHE
#define MIN_POOL_WRITE (32)
#define MIN_POOL_COMMIT (4)
/*
* Local function declarations
*/
static struct nfs_page * nfs_update_request(struct nfs_open_context*,
struct inode *,
struct page *,
unsigned int, unsigned int);
static void nfs_writeback_done_partial(struct nfs_write_data *, int);
static void nfs_writeback_done_full(struct nfs_write_data *, int);
static int nfs_wait_on_write_congestion(struct address_space *, int);
static int nfs_wait_on_requests(struct inode *, unsigned long, unsigned int);
static int nfs_flush_inode(struct inode *inode, unsigned long idx_start,
unsigned int npages, int how);
static kmem_cache_t *nfs_wdata_cachep;
mempool_t *nfs_wdata_mempool;
static mempool_t *nfs_commit_mempool;
static DECLARE_WAIT_QUEUE_HEAD(nfs_write_congestion);
static inline struct nfs_write_data *nfs_commit_alloc(unsigned int pagecount)
{
struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, SLAB_NOFS);
if (p) {
memset(p, 0, sizeof(*p));
INIT_LIST_HEAD(&p->pages);
if (pagecount < NFS_PAGEVEC_SIZE)
p->pagevec = &p->page_array[0];
else {
size_t size = ++pagecount * sizeof(struct page *);
p->pagevec = kmalloc(size, GFP_NOFS);
if (p->pagevec) {
memset(p->pagevec, 0, size);
} else {
mempool_free(p, nfs_commit_mempool);
p = NULL;
}
}
}
return p;
}
static inline void nfs_commit_free(struct nfs_write_data *p)
{
if (p && (p->pagevec != &p->page_array[0]))
kfree(p->pagevec);
mempool_free(p, nfs_commit_mempool);
}
void nfs_writedata_release(void *wdata)
{
nfs_writedata_free(wdata);
}
/* Adjust the file length if we're writing beyond the end */
static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
{
struct inode *inode = page->mapping->host;
loff_t end, i_size = i_size_read(inode);
unsigned long end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
if (i_size > 0 && page->index < end_index)
return;
end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
if (i_size >= end)
return;
i_size_write(inode, end);
}
/* We can set the PG_uptodate flag if we see that a write request
* covers the full page.
*/
static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
{
loff_t end_offs;
if (PageUptodate(page))
return;
if (base != 0)
return;
if (count == PAGE_CACHE_SIZE) {
SetPageUptodate(page);
return;
}
end_offs = i_size_read(page->mapping->host) - 1;
if (end_offs < 0)
return;
/* Is this the last page? */
if (page->index != (unsigned long)(end_offs >> PAGE_CACHE_SHIFT))
return;
/* This is the last page: set PG_uptodate if we cover the entire
* extent of the data, then zero the rest of the page.
*/
if (count == (unsigned int)(end_offs & (PAGE_CACHE_SIZE - 1)) + 1) {
memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
SetPageUptodate(page);
}
}
/*
* Write a page synchronously.
* Offset is the data offset within the page.
*/
static int nfs_writepage_sync(struct nfs_open_context *ctx, struct inode *inode,
struct page *page, unsigned int offset, unsigned int count,
int how)
{
unsigned int wsize = NFS_SERVER(inode)->wsize;
int result, written = 0;
struct nfs_write_data *wdata;
wdata = nfs_writedata_alloc(1);
if (!wdata)
return -ENOMEM;
wdata->flags = how;
wdata->cred = ctx->cred;
wdata->inode = inode;
wdata->args.fh = NFS_FH(inode);
wdata->args.context = ctx;
wdata->args.pages = &page;
wdata->args.stable = NFS_FILE_SYNC;
wdata->args.pgbase = offset;
wdata->args.count = wsize;
wdata->res.fattr = &wdata->fattr;
wdata->res.verf = &wdata->verf;
dprintk("NFS: nfs_writepage_sync(%s/%Ld %d@%Ld)\n",
inode->i_sb->s_id,
(long long)NFS_FILEID(inode),
count, (long long)(page_offset(page) + offset));
set_page_writeback(page);
nfs_begin_data_update(inode);
do {
if (count < wsize)
wdata->args.count = count;
wdata->args.offset = page_offset(page) + wdata->args.pgbase;
result = NFS_PROTO(inode)->write(wdata);
if (result < 0) {
/* Must mark the page invalid after I/O error */
ClearPageUptodate(page);
goto io_error;
}
if (result < wdata->args.count)
printk(KERN_WARNING "NFS: short write, count=%u, result=%d\n",
wdata->args.count, result);
wdata->args.offset += result;
wdata->args.pgbase += result;
written += result;
count -= result;
} while (count);
/* Update file length */
nfs_grow_file(page, offset, written);
/* Set the PG_uptodate flag? */
nfs_mark_uptodate(page, offset, written);
if (PageError(page))
ClearPageError(page);
io_error:
nfs_end_data_update(inode);
end_page_writeback(page);
nfs_writedata_free(wdata);
return written ? written : result;
}
static int nfs_writepage_async(struct nfs_open_context *ctx,
struct inode *inode, struct page *page,
unsigned int offset, unsigned int count)
{
struct nfs_page *req;
req = nfs_update_request(ctx, inode, page, offset, count);
if (IS_ERR(req))
return PTR_ERR(req);
/* Update file length */
nfs_grow_file(page, offset, count);
/* Set the PG_uptodate flag? */
nfs_mark_uptodate(page, offset, count);
nfs_unlock_request(req);
return 0;
}
static int wb_priority(struct writeback_control *wbc)
{
if (wbc->for_reclaim)
return FLUSH_HIGHPRI;
if (wbc->for_kupdate)
return FLUSH_LOWPRI;
return 0;
}
/*
* Write an mmapped page to the server.
*/
int nfs_writepage(struct page *page, struct writeback_control *wbc)
{
struct nfs_open_context *ctx;
struct inode *inode = page->mapping->host;
unsigned long end_index;
unsigned offset = PAGE_CACHE_SIZE;
loff_t i_size = i_size_read(inode);
int inode_referenced = 0;
int priority = wb_priority(wbc);
int err;
/*
* Note: We need to ensure that we have a reference to the inode
* if we are to do asynchronous writes. If not, waiting
* in nfs_wait_on_request() may deadlock with clear_inode().
*
* If igrab() fails here, then it is in any case safe to
* call nfs_wb_page(), since there will be no pending writes.
*/
if (igrab(inode) != 0)
inode_referenced = 1;
end_index = i_size >> PAGE_CACHE_SHIFT;
/* Ensure we've flushed out any previous writes */
nfs_wb_page_priority(inode, page, priority);
/* easy case */
if (page->index < end_index)
goto do_it;
/* things got complicated... */
offset = i_size & (PAGE_CACHE_SIZE-1);
/* OK, are we completely out? */
err = 0; /* potential race with truncate - ignore */
if (page->index >= end_index+1 || !offset)
goto out;
do_it:
ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
if (ctx == NULL) {
err = -EBADF;
goto out;
}
lock_kernel();
if (!IS_SYNC(inode) && inode_referenced) {
err = nfs_writepage_async(ctx, inode, page, 0, offset);
if (!wbc->for_writepages)
nfs_flush_inode(inode, 0, 0, wb_priority(wbc));
} else {
err = nfs_writepage_sync(ctx, inode, page, 0,
offset, priority);
if (err >= 0) {
if (err != offset)
redirty_page_for_writepage(wbc, page);
err = 0;
}
}
unlock_kernel();
put_nfs_open_context(ctx);
out:
unlock_page(page);
if (inode_referenced)
iput(inode);
return err;
}
/*
* Note: causes nfs_update_request() to block on the assumption
* that the writeback is generated due to memory pressure.
*/
int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
struct backing_dev_info *bdi = mapping->backing_dev_info;
struct inode *inode = mapping->host;
int err;
err = generic_writepages(mapping, wbc);
if (err)
return err;
while (test_and_set_bit(BDI_write_congested, &bdi->state) != 0) {
if (wbc->nonblocking)
return 0;
nfs_wait_on_write_congestion(mapping, 0);
}
err = nfs_flush_inode(inode, 0, 0, wb_priority(wbc));
if (err < 0)
goto out;
wbc->nr_to_write -= err;
if (!wbc->nonblocking && wbc->sync_mode == WB_SYNC_ALL) {
err = nfs_wait_on_requests(inode, 0, 0);
if (err < 0)
goto out;
}
err = nfs_commit_inode(inode, wb_priority(wbc));
if (err > 0) {
wbc->nr_to_write -= err;
err = 0;
}
out:
clear_bit(BDI_write_congested, &bdi->state);
wake_up_all(&nfs_write_congestion);
return err;
}
/*
* Insert a write request into an inode
*/
static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
{
struct nfs_inode *nfsi = NFS_I(inode);
int error;
error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
BUG_ON(error == -EEXIST);
if (error)
return error;
if (!nfsi->npages) {
igrab(inode);
nfs_begin_data_update(inode);
if (nfs_have_delegation(inode, FMODE_WRITE))
nfsi->change_attr++;
}
nfsi->npages++;
atomic_inc(&req->wb_count);
return 0;
}
/*
* Insert a write request into an inode
*/
static void nfs_inode_remove_request(struct nfs_page *req)
{
struct inode *inode = req->wb_context->dentry->d_inode;
struct nfs_inode *nfsi = NFS_I(inode);
BUG_ON (!NFS_WBACK_BUSY(req));
spin_lock(&nfsi->req_lock);
radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
nfsi->npages--;
if (!nfsi->npages) {
spin_unlock(&nfsi->req_lock);
nfs_end_data_update(inode);
iput(inode);
} else
spin_unlock(&nfsi->req_lock);
nfs_clear_request(req);
nfs_release_request(req);
}
/*
* Find a request
*/
static inline struct nfs_page *
_nfs_find_request(struct inode *inode, unsigned long index)
{
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_page *req;
req = (struct nfs_page*)radix_tree_lookup(&nfsi->nfs_page_tree, index);
if (req)
atomic_inc(&req->wb_count);
return req;
}
static struct nfs_page *
nfs_find_request(struct inode *inode, unsigned long index)
{
struct nfs_page *req;
struct nfs_inode *nfsi = NFS_I(inode);
spin_lock(&nfsi->req_lock);
req = _nfs_find_request(inode, index);
spin_unlock(&nfsi->req_lock);
return req;
}
/*
* Add a request to the inode's dirty list.
*/
static void
nfs_mark_request_dirty(struct nfs_page *req)
{
struct inode *inode = req->wb_context->dentry->d_inode;
struct nfs_inode *nfsi = NFS_I(inode);
spin_lock(&nfsi->req_lock);
radix_tree_tag_set(&nfsi->nfs_page_tree,
req->wb_index, NFS_PAGE_TAG_DIRTY);
nfs_list_add_request(req, &nfsi->dirty);
nfsi->ndirty++;
spin_unlock(&nfsi->req_lock);
inc_page_state(nr_dirty);
mark_inode_dirty(inode);
}
/*
* Check if a request is dirty
*/
static inline int
nfs_dirty_request(struct nfs_page *req)
{
struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
return !list_empty(&req->wb_list) && req->wb_list_head == &nfsi->dirty;
}
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
/*
* Add a request to the inode's commit list.
*/
static void
nfs_mark_request_commit(struct nfs_page *req)
{
struct inode *inode = req->wb_context->dentry->d_inode;
struct nfs_inode *nfsi = NFS_I(inode);
spin_lock(&nfsi->req_lock);
nfs_list_add_request(req, &nfsi->commit);
nfsi->ncommit++;
spin_unlock(&nfsi->req_lock);
inc_page_state(nr_unstable);
mark_inode_dirty(inode);
}
#endif
/*
* Wait for a request to complete.
*
* Interruptible by signals only if mounted with intr flag.
*/
static int
nfs_wait_on_requests(struct inode *inode, unsigned long idx_start, unsigned int npages)
{
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_page *req;
unsigned long idx_end, next;
unsigned int res = 0;
int error;
if (npages == 0)
idx_end = ~0;
else
idx_end = idx_start + npages - 1;
spin_lock(&nfsi->req_lock);
next = idx_start;
while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
if (req->wb_index > idx_end)
break;
next = req->wb_index + 1;
BUG_ON(!NFS_WBACK_BUSY(req));
atomic_inc(&req->wb_count);
spin_unlock(&nfsi->req_lock);
error = nfs_wait_on_request(req);
nfs_release_request(req);
if (error < 0)
return error;
spin_lock(&nfsi->req_lock);
res++;
}
spin_unlock(&nfsi->req_lock);
return res;
}
/*
* nfs_scan_dirty - Scan an inode for dirty requests
* @inode: NFS inode to scan
* @dst: destination list
* @idx_start: lower bound of page->index to scan.
* @npages: idx_start + npages sets the upper bound to scan.
*
* Moves requests from the inode's dirty page list.
* The requests are *not* checked to ensure that they form a contiguous set.
*/
static int
nfs_scan_dirty(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
{
struct nfs_inode *nfsi = NFS_I(inode);
int res = 0;
if (nfsi->ndirty != 0) {
res = nfs_scan_lock_dirty(nfsi, dst, idx_start, npages);
nfsi->ndirty -= res;
sub_page_state(nr_dirty,res);
if ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty))
printk(KERN_ERR "NFS: desynchronized value of nfs_i.ndirty.\n");
}
return res;
}
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
/*
* nfs_scan_commit - Scan an inode for commit requests
* @inode: NFS inode to scan
* @dst: destination list
* @idx_start: lower bound of page->index to scan.
* @npages: idx_start + npages sets the upper bound to scan.
*
* Moves requests from the inode's 'commit' request list.
* The requests are *not* checked to ensure that they form a contiguous set.
*/
static int
nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
{
struct nfs_inode *nfsi = NFS_I(inode);
int res = 0;
if (nfsi->ncommit != 0) {
res = nfs_scan_list(&nfsi->commit, dst, idx_start, npages);
nfsi->ncommit -= res;
if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
}
return res;
}
#endif
static int nfs_wait_on_write_congestion(struct address_space *mapping, int intr)
{
struct backing_dev_info *bdi = mapping->backing_dev_info;
DEFINE_WAIT(wait);
int ret = 0;
might_sleep();
if (!bdi_write_congested(bdi))
return 0;
if (intr) {
struct rpc_clnt *clnt = NFS_CLIENT(mapping->host);
sigset_t oldset;
rpc_clnt_sigmask(clnt, &oldset);
prepare_to_wait(&nfs_write_congestion, &wait, TASK_INTERRUPTIBLE);
if (bdi_write_congested(bdi)) {
if (signalled())
ret = -ERESTARTSYS;
else
schedule();
}
rpc_clnt_sigunmask(clnt, &oldset);
} else {
prepare_to_wait(&nfs_write_congestion, &wait, TASK_UNINTERRUPTIBLE);
if (bdi_write_congested(bdi))
schedule();
}
finish_wait(&nfs_write_congestion, &wait);
return ret;
}
/*
* Try to update any existing write request, or create one if there is none.
* In order to match, the request's credentials must match those of
* the calling process.
*
* Note: Should always be called with the Page Lock held!
*/
static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
struct inode *inode, struct page *page,
unsigned int offset, unsigned int bytes)
{
struct nfs_server *server = NFS_SERVER(inode);
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_page *req, *new = NULL;
unsigned long rqend, end;
end = offset + bytes;
if (nfs_wait_on_write_congestion(page->mapping, server->flags & NFS_MOUNT_INTR))
return ERR_PTR(-ERESTARTSYS);
for (;;) {
/* Loop over all inode entries and see if we find
* A request for the page we wish to update
*/
spin_lock(&nfsi->req_lock);
req = _nfs_find_request(inode, page->index);
if (req) {
if (!nfs_lock_request_dontget(req)) {
int error;
spin_unlock(&nfsi->req_lock);
error = nfs_wait_on_request(req);
nfs_release_request(req);
if (error < 0)
return ERR_PTR(error);
continue;
}
spin_unlock(&nfsi->req_lock);
if (new)
nfs_release_request(new);
break;
}
if (new) {
int error;
nfs_lock_request_dontget(new);
error = nfs_inode_add_request(inode, new);
if (error) {
spin_unlock(&nfsi->req_lock);
nfs_unlock_request(new);
return ERR_PTR(error);
}
spin_unlock(&nfsi->req_lock);
nfs_mark_request_dirty(new);
return new;
}
spin_unlock(&nfsi->req_lock);
new = nfs_create_request(ctx, inode, page, offset, bytes);
if (IS_ERR(new))
return new;
}
/* We have a request for our page.
* If the creds don't match, or the
* page addresses don't match,
* tell the caller to wait on the conflicting
* request.
*/
rqend = req->wb_offset + req->wb_bytes;
if (req->wb_context != ctx
|| req->wb_page != page
|| !nfs_dirty_request(req)
|| offset > rqend || end < req->wb_offset) {
nfs_unlock_request(req);
return ERR_PTR(-EBUSY);
}
/* Okay, the request matches. Update the region */
if (offset < req->wb_offset) {
req->wb_offset = offset;
req->wb_pgbase = offset;
req->wb_bytes = rqend - req->wb_offset;
}
if (end > rqend)
req->wb_bytes = end - req->wb_offset;
return req;
}
int nfs_flush_incompatible(struct file *file, struct page *page)
{
struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
struct inode *inode = page->mapping->host;
struct nfs_page *req;
int status = 0;
/*
* Look for a request corresponding to this page. If there
* is one, and it belongs to another file, we flush it out
* before we try to copy anything into the page. Do this
* due to the lack of an ACCESS-type call in NFSv2.
* Also do the same if we find a request from an existing
* dropped page.
*/
req = nfs_find_request(inode, page->index);
if (req) {
if (req->wb_page != page || ctx != req->wb_context)
status = nfs_wb_page(inode, page);
nfs_release_request(req);
}
return (status < 0) ? status : 0;
}
/*
* Update and possibly write a cached page of an NFS file.
*
* XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
* things with a page scheduled for an RPC call (e.g. invalidate it).
*/
int nfs_updatepage(struct file *file, struct page *page,
unsigned int offset, unsigned int count)
{
struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
struct inode *inode = page->mapping->host;
struct nfs_page *req;
int status = 0;
dprintk("NFS: nfs_updatepage(%s/%s %d@%Ld)\n",
file->f_dentry->d_parent->d_name.name,
file->f_dentry->d_name.name, count,
(long long)(page_offset(page) +offset));
if (IS_SYNC(inode)) {
status = nfs_writepage_sync(ctx, inode, page, offset, count, 0);
if (status > 0) {
if (offset == 0 && status == PAGE_CACHE_SIZE)
SetPageUptodate(page);
return 0;
}
return status;
}
/* If we're not using byte range locks, and we know the page
* is entirely in cache, it may be more efficient to avoid
* fragmenting write requests.
*/
if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
loff_t end_offs = i_size_read(inode) - 1;
unsigned long end_index = end_offs >> PAGE_CACHE_SHIFT;
count += offset;
offset = 0;
if (unlikely(end_offs < 0)) {
/* Do nothing */
} else if (page->index == end_index) {
unsigned int pglen;
pglen = (unsigned int)(end_offs & (PAGE_CACHE_SIZE-1)) + 1;
if (count < pglen)
count = pglen;
} else if (page->index < end_index)
count = PAGE_CACHE_SIZE;
}
/*
* Try to find an NFS request corresponding to this page
* and update it.
* If the existing request cannot be updated, we must flush
* it out now.
*/
do {
req = nfs_update_request(ctx, inode, page, offset, count);
status = (IS_ERR(req)) ? PTR_ERR(req) : 0;
if (status != -EBUSY)
break;
/* Request could not be updated. Flush it out and try again */
status = nfs_wb_page(inode, page);
} while (status >= 0);
if (status < 0)
goto done;
status = 0;
/* Update file length */
nfs_grow_file(page, offset, count);
/* Set the PG_uptodate flag? */
nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
nfs_unlock_request(req);
done:
dprintk("NFS: nfs_updatepage returns %d (isize %Ld)\n",
status, (long long)i_size_read(inode));
if (status < 0)
ClearPageUptodate(page);
return status;
}
static void nfs_writepage_release(struct nfs_page *req)
{
end_page_writeback(req->wb_page);
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
if (!PageError(req->wb_page)) {
if (NFS_NEED_RESCHED(req)) {
nfs_mark_request_dirty(req);
goto out;
} else if (NFS_NEED_COMMIT(req)) {
nfs_mark_request_commit(req);
goto out;
}
}
nfs_inode_remove_request(req);
out:
nfs_clear_commit(req);
nfs_clear_reschedule(req);
#else
nfs_inode_remove_request(req);
#endif
nfs_clear_page_writeback(req);
}
static inline int flush_task_priority(int how)
{
switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
case FLUSH_HIGHPRI:
return RPC_PRIORITY_HIGH;
case FLUSH_LOWPRI:
return RPC_PRIORITY_LOW;
}
return RPC_PRIORITY_NORMAL;
}
/*
* Set up the argument/result storage required for the RPC call.
*/
static void nfs_write_rpcsetup(struct nfs_page *req,
struct nfs_write_data *data,
unsigned int count, unsigned int offset,
int how)
{
struct inode *inode;
/* Set up the RPC argument and reply structs
* NB: take care not to mess about with data->commit et al. */
data->req = req;
data->inode = inode = req->wb_context->dentry->d_inode;
data->cred = req->wb_context->cred;
data->args.fh = NFS_FH(inode);
data->args.offset = req_offset(req) + offset;
data->args.pgbase = req->wb_pgbase + offset;
data->args.pages = data->pagevec;
data->args.count = count;
data->args.context = req->wb_context;
data->res.fattr = &data->fattr;
data->res.count = count;
data->res.verf = &data->verf;
nfs_fattr_init(&data->fattr);
NFS_PROTO(inode)->write_setup(data, how);
data->task.tk_priority = flush_task_priority(how);
data->task.tk_cookie = (unsigned long)inode;
dprintk("NFS: %4d initiated write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
data->task.tk_pid,
inode->i_sb->s_id,
(long long)NFS_FILEID(inode),
count,
(unsigned long long)data->args.offset);
}
static void nfs_execute_write(struct nfs_write_data *data)
{
struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
sigset_t oldset;
rpc_clnt_sigmask(clnt, &oldset);
lock_kernel();
rpc_execute(&data->task);
unlock_kernel();
rpc_clnt_sigunmask(clnt, &oldset);
}
/*
* Generate multiple small requests to write out a single
* contiguous dirty area on one page.
*/
static int nfs_flush_multi(struct list_head *head, struct inode *inode, int how)
{
struct nfs_page *req = nfs_list_entry(head->next);
struct page *page = req->wb_page;
struct nfs_write_data *data;
unsigned int wsize = NFS_SERVER(inode)->wsize;
unsigned int nbytes, offset;
int requests = 0;
LIST_HEAD(list);
nfs_list_remove_request(req);
nbytes = req->wb_bytes;
for (;;) {
data = nfs_writedata_alloc(1);
if (!data)
goto out_bad;
list_add(&data->pages, &list);
requests++;
if (nbytes <= wsize)
break;
nbytes -= wsize;
}
atomic_set(&req->wb_complete, requests);
ClearPageError(page);
set_page_writeback(page);
offset = 0;
nbytes = req->wb_bytes;
do {
data = list_entry(list.next, struct nfs_write_data, pages);
list_del_init(&data->pages);
data->pagevec[0] = page;
data->complete = nfs_writeback_done_partial;
if (nbytes > wsize) {
nfs_write_rpcsetup(req, data, wsize, offset, how);
offset += wsize;
nbytes -= wsize;
} else {
nfs_write_rpcsetup(req, data, nbytes, offset, how);
nbytes = 0;
}
nfs_execute_write(data);
} while (nbytes != 0);
return 0;
out_bad:
while (!list_empty(&list)) {
data = list_entry(list.next, struct nfs_write_data, pages);
list_del(&data->pages);
nfs_writedata_free(data);
}
nfs_mark_request_dirty(req);
nfs_clear_page_writeback(req);
return -ENOMEM;
}
/*
* Create an RPC task for the given write request and kick it.
* The page must have been locked by the caller.
*
* It may happen that the page we're passed is not marked dirty.
* This is the case if nfs_updatepage detects a conflicting request
* that has been written but not committed.
*/
static int nfs_flush_one(struct list_head *head, struct inode *inode, int how)
{
struct nfs_page *req;
struct page **pages;
struct nfs_write_data *data;
unsigned int count;
if (NFS_SERVER(inode)->wsize < PAGE_CACHE_SIZE)
return nfs_flush_multi(head, inode, how);
data = nfs_writedata_alloc(NFS_SERVER(inode)->wpages);
if (!data)
goto out_bad;
pages = data->pagevec;
count = 0;
while (!list_empty(head)) {
req = nfs_list_entry(head->next);
nfs_list_remove_request(req);
nfs_list_add_request(req, &data->pages);