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linux-next/fs/nfs/write.c
Trond Myklebust 61e930a904 NFS: Fix a writeback race...
This patch fixes a regression that was introduced by commit
44dd151d5c

We cannot zero the user page in nfs_mark_uptodate() any more, since

  a) We'd be modifying the page without holding the page lock
  b) We can race with other updates of the page, most notably
     because of the call to nfs_wb_page() in nfs_writepage_setup().

Instead, we do the zeroing in nfs_update_request() if we see that we're
creating a request that might potentially be marked as up to date.

Thanks to Olivier Paquet for reporting the bug and providing a test-case.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2007-10-19 17:18:57 -04:00

1525 lines
38 KiB
C

/*
* linux/fs/nfs/write.c
*
* Write file data over NFS.
*
* Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
*/
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/writeback.h>
#include <linux/swap.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs_page.h>
#include <linux/backing-dev.h>
#include <asm/uaccess.h>
#include "delegation.h"
#include "internal.h"
#include "iostat.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 page *,
unsigned int, unsigned int);
static void nfs_pageio_init_write(struct nfs_pageio_descriptor *desc,
struct inode *inode, int ioflags);
static const struct rpc_call_ops nfs_write_partial_ops;
static const struct rpc_call_ops nfs_write_full_ops;
static const struct rpc_call_ops nfs_commit_ops;
static struct kmem_cache *nfs_wdata_cachep;
static mempool_t *nfs_wdata_mempool;
static mempool_t *nfs_commit_mempool;
struct nfs_write_data *nfs_commit_alloc(void)
{
struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
if (p) {
memset(p, 0, sizeof(*p));
INIT_LIST_HEAD(&p->pages);
}
return p;
}
static void nfs_commit_rcu_free(struct rcu_head *head)
{
struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
if (p && (p->pagevec != &p->page_array[0]))
kfree(p->pagevec);
mempool_free(p, nfs_commit_mempool);
}
void nfs_commit_free(struct nfs_write_data *wdata)
{
call_rcu_bh(&wdata->task.u.tk_rcu, nfs_commit_rcu_free);
}
struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
{
struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
if (p) {
memset(p, 0, sizeof(*p));
INIT_LIST_HEAD(&p->pages);
p->npages = pagecount;
if (pagecount <= ARRAY_SIZE(p->page_array))
p->pagevec = p->page_array;
else {
p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
if (!p->pagevec) {
mempool_free(p, nfs_wdata_mempool);
p = NULL;
}
}
}
return p;
}
static void nfs_writedata_rcu_free(struct rcu_head *head)
{
struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
if (p && (p->pagevec != &p->page_array[0]))
kfree(p->pagevec);
mempool_free(p, nfs_wdata_mempool);
}
static void nfs_writedata_free(struct nfs_write_data *wdata)
{
call_rcu_bh(&wdata->task.u.tk_rcu, nfs_writedata_rcu_free);
}
void nfs_writedata_release(void *wdata)
{
nfs_writedata_free(wdata);
}
static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
{
ctx->error = error;
smp_wmb();
set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
}
static struct nfs_page *nfs_page_find_request_locked(struct page *page)
{
struct nfs_page *req = NULL;
if (PagePrivate(page)) {
req = (struct nfs_page *)page_private(page);
if (req != NULL)
kref_get(&req->wb_kref);
}
return req;
}
static struct nfs_page *nfs_page_find_request(struct page *page)
{
struct inode *inode = page->mapping->host;
struct nfs_page *req = NULL;
spin_lock(&inode->i_lock);
req = nfs_page_find_request_locked(page);
spin_unlock(&inode->i_lock);
return req;
}
/* 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);
pgoff_t 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;
nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
i_size_write(inode, end);
}
/* A writeback failed: mark the page as bad, and invalidate the page cache */
static void nfs_set_pageerror(struct page *page)
{
SetPageError(page);
nfs_zap_mapping(page->mapping->host, page->mapping);
}
/* 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)
{
if (PageUptodate(page))
return;
if (base != 0)
return;
if (count != nfs_page_length(page))
return;
SetPageUptodate(page);
}
static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
unsigned int offset, unsigned int count)
{
struct nfs_page *req;
int ret;
for (;;) {
req = nfs_update_request(ctx, page, offset, count);
if (!IS_ERR(req))
break;
ret = PTR_ERR(req);
if (ret != -EBUSY)
return ret;
ret = nfs_wb_page(page->mapping->host, page);
if (ret != 0)
return ret;
}
/* Update file length */
nfs_grow_file(page, offset, count);
nfs_unlock_request(req);
return 0;
}
static int wb_priority(struct writeback_control *wbc)
{
if (wbc->for_reclaim)
return FLUSH_HIGHPRI | FLUSH_STABLE;
if (wbc->for_kupdate)
return FLUSH_LOWPRI;
return 0;
}
/*
* NFS congestion control
*/
int nfs_congestion_kb;
#define NFS_CONGESTION_ON_THRESH (nfs_congestion_kb >> (PAGE_SHIFT-10))
#define NFS_CONGESTION_OFF_THRESH \
(NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
static int nfs_set_page_writeback(struct page *page)
{
int ret = test_set_page_writeback(page);
if (!ret) {
struct inode *inode = page->mapping->host;
struct nfs_server *nfss = NFS_SERVER(inode);
if (atomic_long_inc_return(&nfss->writeback) >
NFS_CONGESTION_ON_THRESH)
set_bdi_congested(&nfss->backing_dev_info, WRITE);
}
return ret;
}
static void nfs_end_page_writeback(struct page *page)
{
struct inode *inode = page->mapping->host;
struct nfs_server *nfss = NFS_SERVER(inode);
end_page_writeback(page);
if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
clear_bdi_congested(&nfss->backing_dev_info, WRITE);
}
/*
* Find an associated nfs write request, and prepare to flush it out
* May return an error if the user signalled nfs_wait_on_request().
*/
static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
struct page *page)
{
struct inode *inode = page->mapping->host;
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_page *req;
int ret;
spin_lock(&inode->i_lock);
for(;;) {
req = nfs_page_find_request_locked(page);
if (req == NULL) {
spin_unlock(&inode->i_lock);
return 0;
}
if (nfs_lock_request_dontget(req))
break;
/* Note: If we hold the page lock, as is the case in nfs_writepage,
* then the call to nfs_lock_request_dontget() will always
* succeed provided that someone hasn't already marked the
* request as dirty (in which case we don't care).
*/
spin_unlock(&inode->i_lock);
ret = nfs_wait_on_request(req);
nfs_release_request(req);
if (ret != 0)
return ret;
spin_lock(&inode->i_lock);
}
if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
/* This request is marked for commit */
spin_unlock(&inode->i_lock);
nfs_unlock_request(req);
nfs_pageio_complete(pgio);
return 0;
}
if (nfs_set_page_writeback(page) != 0) {
spin_unlock(&inode->i_lock);
BUG();
}
radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
NFS_PAGE_TAG_LOCKED);
spin_unlock(&inode->i_lock);
nfs_pageio_add_request(pgio, req);
return 0;
}
static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
{
struct inode *inode = page->mapping->host;
nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
nfs_pageio_cond_complete(pgio, page->index);
return nfs_page_async_flush(pgio, page);
}
/*
* Write an mmapped page to the server.
*/
static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
{
struct nfs_pageio_descriptor pgio;
int err;
nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
err = nfs_do_writepage(page, wbc, &pgio);
nfs_pageio_complete(&pgio);
if (err < 0)
return err;
if (pgio.pg_error < 0)
return pgio.pg_error;
return 0;
}
int nfs_writepage(struct page *page, struct writeback_control *wbc)
{
int ret;
ret = nfs_writepage_locked(page, wbc);
unlock_page(page);
return ret;
}
static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
{
int ret;
ret = nfs_do_writepage(page, wbc, data);
unlock_page(page);
return ret;
}
int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
struct inode *inode = mapping->host;
struct nfs_pageio_descriptor pgio;
int err;
nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
nfs_pageio_complete(&pgio);
if (err < 0)
return err;
if (pgio.pg_error < 0)
return pgio.pg_error;
return 0;
}
/*
* 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);
if (nfs_have_delegation(inode, FMODE_WRITE))
nfsi->change_attr++;
}
SetPagePrivate(req->wb_page);
set_page_private(req->wb_page, (unsigned long)req);
nfsi->npages++;
kref_get(&req->wb_kref);
return 0;
}
/*
* Remove a write request from an inode
*/
static void nfs_inode_remove_request(struct nfs_page *req)
{
struct inode *inode = req->wb_context->path.dentry->d_inode;
struct nfs_inode *nfsi = NFS_I(inode);
BUG_ON (!NFS_WBACK_BUSY(req));
spin_lock(&inode->i_lock);
set_page_private(req->wb_page, 0);
ClearPagePrivate(req->wb_page);
radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
nfsi->npages--;
if (!nfsi->npages) {
spin_unlock(&inode->i_lock);
iput(inode);
} else
spin_unlock(&inode->i_lock);
nfs_clear_request(req);
nfs_release_request(req);
}
static void
nfs_redirty_request(struct nfs_page *req)
{
__set_page_dirty_nobuffers(req->wb_page);
}
/*
* Check if a request is dirty
*/
static inline int
nfs_dirty_request(struct nfs_page *req)
{
struct page *page = req->wb_page;
if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
return 0;
return !PageWriteback(req->wb_page);
}
#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->path.dentry->d_inode;
struct nfs_inode *nfsi = NFS_I(inode);
spin_lock(&inode->i_lock);
nfsi->ncommit++;
set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
radix_tree_tag_set(&nfsi->nfs_page_tree,
req->wb_index,
NFS_PAGE_TAG_COMMIT);
spin_unlock(&inode->i_lock);
inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
}
static inline
int nfs_write_need_commit(struct nfs_write_data *data)
{
return data->verf.committed != NFS_FILE_SYNC;
}
static inline
int nfs_reschedule_unstable_write(struct nfs_page *req)
{
if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
nfs_mark_request_commit(req);
return 1;
}
if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
nfs_redirty_request(req);
return 1;
}
return 0;
}
#else
static inline void
nfs_mark_request_commit(struct nfs_page *req)
{
}
static inline
int nfs_write_need_commit(struct nfs_write_data *data)
{
return 0;
}
static inline
int nfs_reschedule_unstable_write(struct nfs_page *req)
{
return 0;
}
#endif
/*
* Wait for a request to complete.
*
* Interruptible by signals only if mounted with intr flag.
*/
static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
{
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_page *req;
pgoff_t idx_end, next;
unsigned int res = 0;
int error;
if (npages == 0)
idx_end = ~0;
else
idx_end = idx_start + npages - 1;
next = idx_start;
while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
if (req->wb_index > idx_end)
break;
next = req->wb_index + 1;
BUG_ON(!NFS_WBACK_BUSY(req));
kref_get(&req->wb_kref);
spin_unlock(&inode->i_lock);
error = nfs_wait_on_request(req);
nfs_release_request(req);
spin_lock(&inode->i_lock);
if (error < 0)
return error;
res++;
}
return res;
}
static void nfs_cancel_commit_list(struct list_head *head)
{
struct nfs_page *req;
while(!list_empty(head)) {
req = nfs_list_entry(head->next);
dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
BDI_RECLAIMABLE);
nfs_list_remove_request(req);
clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
nfs_inode_remove_request(req);
nfs_unlock_request(req);
}
}
#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, pgoff_t idx_start, unsigned int npages)
{
struct nfs_inode *nfsi = NFS_I(inode);
int res = 0;
if (nfsi->ncommit != 0) {
res = nfs_scan_list(nfsi, dst, idx_start, npages,
NFS_PAGE_TAG_COMMIT);
nfsi->ncommit -= res;
}
return res;
}
#else
static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
{
return 0;
}
#endif
/*
* 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 page *page, unsigned int offset, unsigned int bytes)
{
struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
struct nfs_page *req, *new = NULL;
pgoff_t rqend, end;
end = offset + bytes;
for (;;) {
/* Loop over all inode entries and see if we find
* A request for the page we wish to update
*/
spin_lock(&inode->i_lock);
req = nfs_page_find_request_locked(page);
if (req) {
if (!nfs_lock_request_dontget(req)) {
int error;
spin_unlock(&inode->i_lock);
error = nfs_wait_on_request(req);
nfs_release_request(req);
if (error < 0) {
if (new)
nfs_release_request(new);
return ERR_PTR(error);
}
continue;
}
spin_unlock(&inode->i_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(&inode->i_lock);
nfs_unlock_request(new);
return ERR_PTR(error);
}
spin_unlock(&inode->i_lock);
req = new;
goto zero_page;
}
spin_unlock(&inode->i_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 = max(end, rqend) - req->wb_offset;
goto zero_page;
}
if (end > rqend)
req->wb_bytes = end - req->wb_offset;
return req;
zero_page:
/* If this page might potentially be marked as up to date,
* then we need to zero any uninitalised data. */
if (req->wb_pgbase == 0 && req->wb_bytes != PAGE_CACHE_SIZE
&& !PageUptodate(req->wb_page))
zero_user_page(req->wb_page, req->wb_bytes,
PAGE_CACHE_SIZE - req->wb_bytes,
KM_USER0);
return req;
}
int nfs_flush_incompatible(struct file *file, struct page *page)
{
struct nfs_open_context *ctx = nfs_file_open_context(file);
struct nfs_page *req;
int do_flush, status;
/*
* 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.
*/
do {
req = nfs_page_find_request(page);
if (req == NULL)
return 0;
do_flush = req->wb_page != page || req->wb_context != ctx
|| !nfs_dirty_request(req);
nfs_release_request(req);
if (!do_flush)
return 0;
status = nfs_wb_page(page->mapping->host, page);
} while (status == 0);
return status;
}
/*
* 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 = nfs_file_open_context(file);
struct inode *inode = page->mapping->host;
int status = 0;
nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
dprintk("NFS: nfs_updatepage(%s/%s %d@%Ld)\n",
file->f_path.dentry->d_parent->d_name.name,
file->f_path.dentry->d_name.name, count,
(long long)(page_offset(page) +offset));
/* 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)) {
count = max(count + offset, nfs_page_length(page));
offset = 0;
}
status = nfs_writepage_setup(ctx, page, offset, count);
__set_page_dirty_nobuffers(page);
dprintk("NFS: nfs_updatepage returns %d (isize %Ld)\n",
status, (long long)i_size_read(inode));
if (status < 0)
nfs_set_pageerror(page);
return status;
}
static void nfs_writepage_release(struct nfs_page *req)
{
if (PageError(req->wb_page)) {
nfs_end_page_writeback(req->wb_page);
nfs_inode_remove_request(req);
} else if (!nfs_reschedule_unstable_write(req)) {
/* Set the PG_uptodate flag */
nfs_mark_uptodate(req->wb_page, req->wb_pgbase, req->wb_bytes);
nfs_end_page_writeback(req->wb_page);
nfs_inode_remove_request(req);
} else
nfs_end_page_writeback(req->wb_page);
nfs_clear_page_tag_locked(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,
const struct rpc_call_ops *call_ops,
unsigned int count, unsigned int offset,
int how)
{
struct inode *inode;
int flags;
/* 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->path.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);
/* Set up the initial task struct. */
flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
NFS_PROTO(inode)->write_setup(data, how);
data->task.tk_priority = flush_task_priority(how);
data->task.tk_cookie = (unsigned long)inode;
dprintk("NFS: %5u 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);
rpc_execute(&data->task);
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 inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
{
struct nfs_page *req = nfs_list_entry(head->next);
struct page *page = req->wb_page;
struct nfs_write_data *data;
size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
unsigned int offset;
int requests = 0;
LIST_HEAD(list);
nfs_list_remove_request(req);
nbytes = count;
do {
size_t len = min(nbytes, wsize);
data = nfs_writedata_alloc(1);
if (!data)
goto out_bad;
list_add(&data->pages, &list);
requests++;
nbytes -= len;
} while (nbytes != 0);
atomic_set(&req->wb_complete, requests);
ClearPageError(page);
offset = 0;
nbytes = count;
do {
data = list_entry(list.next, struct nfs_write_data, pages);
list_del_init(&data->pages);
data->pagevec[0] = page;
if (nbytes < wsize)
wsize = nbytes;
nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
wsize, offset, how);
offset += wsize;
nbytes -= wsize;
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_release(data);
}
nfs_redirty_request(req);
nfs_end_page_writeback(req->wb_page);
nfs_clear_page_tag_locked(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 inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
{
struct nfs_page *req;
struct page **pages;
struct nfs_write_data *data;
data = nfs_writedata_alloc(npages);
if (!data)
goto out_bad;
pages = data->pagevec;
while (!list_empty(head)) {
req = nfs_list_entry(head->next);
nfs_list_remove_request(req);
nfs_list_add_request(req, &data->pages);
ClearPageError(req->wb_page);
*pages++ = req->wb_page;
}
req = nfs_list_entry(data->pages.next);
/* Set up the argument struct */
nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
nfs_execute_write(data);
return 0;
out_bad:
while (!list_empty(head)) {
req = nfs_list_entry(head->next);
nfs_list_remove_request(req);
nfs_redirty_request(req);
nfs_end_page_writeback(req->wb_page);
nfs_clear_page_tag_locked(req);
}
return -ENOMEM;
}
static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
struct inode *inode, int ioflags)
{
int wsize = NFS_SERVER(inode)->wsize;
if (wsize < PAGE_CACHE_SIZE)
nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
else
nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
}
/*
* Handle a write reply that flushed part of a page.
*/
static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
{
struct nfs_write_data *data = calldata;
struct nfs_page *req = data->req;
struct page *page = req->wb_page;
dprintk("NFS: write (%s/%Ld %d@%Ld)",
req->wb_context->path.dentry->d_inode->i_sb->s_id,
(long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
req->wb_bytes,
(long long)req_offset(req));
if (nfs_writeback_done(task, data) != 0)
return;
if (task->tk_status < 0) {
nfs_set_pageerror(page);
nfs_context_set_write_error(req->wb_context, task->tk_status);
dprintk(", error = %d\n", task->tk_status);
goto out;
}
if (nfs_write_need_commit(data)) {
struct inode *inode = page->mapping->host;
spin_lock(&inode->i_lock);
if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
/* Do nothing we need to resend the writes */
} else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
dprintk(" defer commit\n");
} else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
set_bit(PG_NEED_RESCHED, &req->wb_flags);
clear_bit(PG_NEED_COMMIT, &req->wb_flags);
dprintk(" server reboot detected\n");
}
spin_unlock(&inode->i_lock);
} else
dprintk(" OK\n");
out:
if (atomic_dec_and_test(&req->wb_complete))
nfs_writepage_release(req);
}
static const struct rpc_call_ops nfs_write_partial_ops = {
.rpc_call_done = nfs_writeback_done_partial,
.rpc_release = nfs_writedata_release,
};
/*
* Handle a write reply that flushes a whole page.
*
* FIXME: There is an inherent race with invalidate_inode_pages and
* writebacks since the page->count is kept > 1 for as long
* as the page has a write request pending.
*/
static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
{
struct nfs_write_data *data = calldata;
struct nfs_page *req;
struct page *page;
if (nfs_writeback_done(task, data) != 0)
return;
/* Update attributes as result of writeback. */
while (!list_empty(&data->pages)) {
req = nfs_list_entry(data->pages.next);
nfs_list_remove_request(req);
page = req->wb_page;
dprintk("NFS: write (%s/%Ld %d@%Ld)",
req->wb_context->path.dentry->d_inode->i_sb->s_id,
(long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
req->wb_bytes,
(long long)req_offset(req));
if (task->tk_status < 0) {
nfs_set_pageerror(page);
nfs_context_set_write_error(req->wb_context, task->tk_status);
dprintk(", error = %d\n", task->tk_status);
goto remove_request;
}
if (nfs_write_need_commit(data)) {
memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
nfs_mark_request_commit(req);
nfs_end_page_writeback(page);
dprintk(" marked for commit\n");
goto next;
}
/* Set the PG_uptodate flag? */
nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
dprintk(" OK\n");
remove_request:
nfs_end_page_writeback(page);
nfs_inode_remove_request(req);
next:
nfs_clear_page_tag_locked(req);
}
}
static const struct rpc_call_ops nfs_write_full_ops = {
.rpc_call_done = nfs_writeback_done_full,
.rpc_release = nfs_writedata_release,
};
/*
* This function is called when the WRITE call is complete.
*/
int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
{
struct nfs_writeargs *argp = &data->args;
struct nfs_writeres *resp = &data->res;
int status;
dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
task->tk_pid, task->tk_status);
/*
* ->write_done will attempt to use post-op attributes to detect
* conflicting writes by other clients. A strict interpretation
* of close-to-open would allow us to continue caching even if
* another writer had changed the file, but some applications
* depend on tighter cache coherency when writing.
*/
status = NFS_PROTO(data->inode)->write_done(task, data);
if (status != 0)
return status;
nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
/* We tried a write call, but the server did not
* commit data to stable storage even though we
* requested it.
* Note: There is a known bug in Tru64 < 5.0 in which
* the server reports NFS_DATA_SYNC, but performs
* NFS_FILE_SYNC. We therefore implement this checking
* as a dprintk() in order to avoid filling syslog.
*/
static unsigned long complain;
if (time_before(complain, jiffies)) {
dprintk("NFS: faulty NFS server %s:"
" (committed = %d) != (stable = %d)\n",
NFS_SERVER(data->inode)->nfs_client->cl_hostname,
resp->verf->committed, argp->stable);
complain = jiffies + 300 * HZ;
}
}
#endif
/* Is this a short write? */
if (task->tk_status >= 0 && resp->count < argp->count) {
static unsigned long complain;
nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
/* Has the server at least made some progress? */
if (resp->count != 0) {
/* Was this an NFSv2 write or an NFSv3 stable write? */
if (resp->verf->committed != NFS_UNSTABLE) {
/* Resend from where the server left off */
argp->offset += resp->count;
argp->pgbase += resp->count;
argp->count -= resp->count;
} else {
/* Resend as a stable write in order to avoid
* headaches in the case of a server crash.
*/
argp->stable = NFS_FILE_SYNC;
}
rpc_restart_call(task);
return -EAGAIN;
}
if (time_before(complain, jiffies)) {
printk(KERN_WARNING
"NFS: Server wrote zero bytes, expected %u.\n",
argp->count);
complain = jiffies + 300 * HZ;
}
/* Can't do anything about it except throw an error. */
task->tk_status = -EIO;
}
return 0;
}
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
void nfs_commit_release(void *wdata)
{
nfs_commit_free(wdata);
}
/*
* Set up the argument/result storage required for the RPC call.
*/
static void nfs_commit_rpcsetup(struct list_head *head,
struct nfs_write_data *data,
int how)
{
struct nfs_page *first;
struct inode *inode;
int flags;
/* Set up the RPC argument and reply structs
* NB: take care not to mess about with data->commit et al. */
list_splice_init(head, &data->pages);
first = nfs_list_entry(data->pages.next);
inode = first->wb_context->path.dentry->d_inode;
data->inode = inode;
data->cred = first->wb_context->cred;
data->args.fh = NFS_FH(data->inode);
/* Note: we always request a commit of the entire inode */
data->args.offset = 0;
data->args.count = 0;
data->res.count = 0;
data->res.fattr = &data->fattr;
data->res.verf = &data->verf;
nfs_fattr_init(&data->fattr);
/* Set up the initial task struct. */
flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
NFS_PROTO(inode)->commit_setup(data, how);
data->task.tk_priority = flush_task_priority(how);
data->task.tk_cookie = (unsigned long)inode;
dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
}
/*
* Commit dirty pages
*/
static int
nfs_commit_list(struct inode *inode, struct list_head *head, int how)
{
struct nfs_write_data *data;
struct nfs_page *req;
data = nfs_commit_alloc();
if (!data)
goto out_bad;
/* Set up the argument struct */
nfs_commit_rpcsetup(head, data, how);
nfs_execute_write(data);
return 0;
out_bad:
while (!list_empty(head)) {
req = nfs_list_entry(head->next);
nfs_list_remove_request(req);
nfs_mark_request_commit(req);
dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
BDI_RECLAIMABLE);
nfs_clear_page_tag_locked(req);
}
return -ENOMEM;
}
/*
* COMMIT call returned
*/
static void nfs_commit_done(struct rpc_task *task, void *calldata)
{
struct nfs_write_data *data = calldata;
struct nfs_page *req;
dprintk("NFS: %5u nfs_commit_done (status %d)\n",
task->tk_pid, task->tk_status);
/* Call the NFS version-specific code */
if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
return;
while (!list_empty(&data->pages)) {
req = nfs_list_entry(data->pages.next);
nfs_list_remove_request(req);
clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
BDI_RECLAIMABLE);
dprintk("NFS: commit (%s/%Ld %d@%Ld)",
req->wb_context->path.dentry->d_inode->i_sb->s_id,
(long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
req->wb_bytes,
(long long)req_offset(req));
if (task->tk_status < 0) {
nfs_context_set_write_error(req->wb_context, task->tk_status);
nfs_inode_remove_request(req);
dprintk(", error = %d\n", task->tk_status);
goto next;
}
/* Okay, COMMIT succeeded, apparently. Check the verifier
* returned by the server against all stored verfs. */
if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
/* We have a match */
/* Set the PG_uptodate flag */
nfs_mark_uptodate(req->wb_page, req->wb_pgbase,
req->wb_bytes);
nfs_inode_remove_request(req);
dprintk(" OK\n");
goto next;
}
/* We have a mismatch. Write the page again */
dprintk(" mismatch\n");
nfs_redirty_request(req);
next:
nfs_clear_page_tag_locked(req);
}
}
static const struct rpc_call_ops nfs_commit_ops = {
.rpc_call_done = nfs_commit_done,
.rpc_release = nfs_commit_release,
};
int nfs_commit_inode(struct inode *inode, int how)
{
LIST_HEAD(head);
int res;
spin_lock(&inode->i_lock);
res = nfs_scan_commit(inode, &head, 0, 0);
spin_unlock(&inode->i_lock);
if (res) {
int error = nfs_commit_list(inode, &head, how);
if (error < 0)
return error;
}
return res;
}
#else
static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
{
return 0;
}
#endif
long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
{
struct inode *inode = mapping->host;
pgoff_t idx_start, idx_end;
unsigned int npages = 0;
LIST_HEAD(head);
int nocommit = how & FLUSH_NOCOMMIT;
long pages, ret;
/* FIXME */
if (wbc->range_cyclic)
idx_start = 0;
else {
idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
if (idx_end > idx_start) {
pgoff_t l_npages = 1 + idx_end - idx_start;
npages = l_npages;
if (sizeof(npages) != sizeof(l_npages) &&
(pgoff_t)npages != l_npages)
npages = 0;
}
}
how &= ~FLUSH_NOCOMMIT;
spin_lock(&inode->i_lock);
do {
ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
if (ret != 0)
continue;
if (nocommit)
break;
pages = nfs_scan_commit(inode, &head, idx_start, npages);
if (pages == 0)
break;
if (how & FLUSH_INVALIDATE) {
spin_unlock(&inode->i_lock);
nfs_cancel_commit_list(&head);
ret = pages;
spin_lock(&inode->i_lock);
continue;
}
pages += nfs_scan_commit(inode, &head, 0, 0);
spin_unlock(&inode->i_lock);
ret = nfs_commit_list(inode, &head, how);
spin_lock(&inode->i_lock);
} while (ret >= 0);
spin_unlock(&inode->i_lock);
return ret;
}
static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
{
int ret;
ret = nfs_writepages(mapping, wbc);
if (ret < 0)
goto out;
ret = nfs_sync_mapping_wait(mapping, wbc, how);
if (ret < 0)
goto out;
return 0;
out:
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
return ret;
}
/* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
static int nfs_write_mapping(struct address_space *mapping, int how)
{
struct writeback_control wbc = {
.bdi = mapping->backing_dev_info,
.sync_mode = WB_SYNC_NONE,
.nr_to_write = LONG_MAX,
.for_writepages = 1,
.range_cyclic = 1,
};
int ret;
ret = __nfs_write_mapping(mapping, &wbc, how);
if (ret < 0)
return ret;
wbc.sync_mode = WB_SYNC_ALL;
return __nfs_write_mapping(mapping, &wbc, how);
}
/*
* flush the inode to disk.
*/
int nfs_wb_all(struct inode *inode)
{
return nfs_write_mapping(inode->i_mapping, 0);
}
int nfs_wb_nocommit(struct inode *inode)
{
return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
}
int nfs_wb_page_cancel(struct inode *inode, struct page *page)
{
struct nfs_page *req;
loff_t range_start = page_offset(page);
loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
struct writeback_control wbc = {
.bdi = page->mapping->backing_dev_info,
.sync_mode = WB_SYNC_ALL,
.nr_to_write = LONG_MAX,
.range_start = range_start,
.range_end = range_end,
};
int ret = 0;
BUG_ON(!PageLocked(page));
for (;;) {
req = nfs_page_find_request(page);
if (req == NULL)
goto out;
if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
nfs_release_request(req);
break;
}
if (nfs_lock_request_dontget(req)) {
nfs_inode_remove_request(req);
/*
* In case nfs_inode_remove_request has marked the
* page as being dirty
*/
cancel_dirty_page(page, PAGE_CACHE_SIZE);
nfs_unlock_request(req);
break;
}
ret = nfs_wait_on_request(req);
if (ret < 0)
goto out;
}
if (!PagePrivate(page))
return 0;
ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);
out:
return ret;
}
int nfs_wb_page_priority(struct inode *inode, struct page *page, int how)
{
loff_t range_start = page_offset(page);
loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
struct writeback_control wbc = {
.bdi = page->mapping->backing_dev_info,
.sync_mode = WB_SYNC_ALL,
.nr_to_write = LONG_MAX,
.range_start = range_start,
.range_end = range_end,
};
int ret;
BUG_ON(!PageLocked(page));
if (clear_page_dirty_for_io(page)) {
ret = nfs_writepage_locked(page, &wbc);
if (ret < 0)
goto out;
}
if (!PagePrivate(page))
return 0;
ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
if (ret >= 0)
return 0;
out:
__mark_inode_dirty(inode, I_DIRTY_PAGES);
return ret;
}
/*
* Write back all requests on one page - we do this before reading it.
*/
int nfs_wb_page(struct inode *inode, struct page* page)
{
return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
}
int __init nfs_init_writepagecache(void)
{
nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
sizeof(struct nfs_write_data),
0, SLAB_HWCACHE_ALIGN,
NULL);
if (nfs_wdata_cachep == NULL)
return -ENOMEM;
nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
nfs_wdata_cachep);
if (nfs_wdata_mempool == NULL)
return -ENOMEM;
nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
nfs_wdata_cachep);
if (nfs_commit_mempool == NULL)
return -ENOMEM;
/*
* NFS congestion size, scale with available memory.
*
* 64MB: 8192k
* 128MB: 11585k
* 256MB: 16384k
* 512MB: 23170k
* 1GB: 32768k
* 2GB: 46340k
* 4GB: 65536k
* 8GB: 92681k
* 16GB: 131072k
*
* This allows larger machines to have larger/more transfers.
* Limit the default to 256M
*/
nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
if (nfs_congestion_kb > 256*1024)
nfs_congestion_kb = 256*1024;
return 0;
}
void nfs_destroy_writepagecache(void)
{
mempool_destroy(nfs_commit_mempool);
mempool_destroy(nfs_wdata_mempool);
kmem_cache_destroy(nfs_wdata_cachep);
}