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NFS: Fix a hang/infinite loop in nfs_wb_page() 

When one of the two waits in nfs_commit_inode() is interrupted, it
returns a non-negative value, which causes nfs_wb_page() to think
that the operation was successful causing it to busy-loop rather
than exiting.
It also causes nfs_file_fsync() to incorrectly report the file as
being successfully committed to disk.

This patch fixes both problems by ensuring that we return an error
if the attempts to wait fail.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org
This commit is contained in:
Trond Myklebust 2011-03-21 15:37:01 -04:00
parent b31268ac79
commit b8413f98f9
1 changed files with 19 additions and 12 deletions
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31
fs/nfs/write.c
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@ -1261,13 +1261,17 @@ void nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4) #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait) static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
{ {
int ret;
if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags)) if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))
return 1; return 1;
if (may_wait && !out_of_line_wait_on_bit_lock(&nfsi->flags, if (!may_wait)
NFS_INO_COMMIT, nfs_wait_bit_killable, return 0;
TASK_KILLABLE)) ret = out_of_line_wait_on_bit_lock(&nfsi->flags,
return 1; NFS_INO_COMMIT,
return 0; nfs_wait_bit_killable,
TASK_KILLABLE);
return (ret < 0) ? ret : 1;
} }
static void nfs_commit_clear_lock(struct nfs_inode *nfsi) static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
@ -1443,9 +1447,10 @@ int nfs_commit_inode(struct inode *inode, int how)
{ {
LIST_HEAD(head); LIST_HEAD(head);
int may_wait = how & FLUSH_SYNC; int may_wait = how & FLUSH_SYNC;
int res = 0; int res;
if (!nfs_commit_set_lock(NFS_I(inode), may_wait)) res = nfs_commit_set_lock(NFS_I(inode), may_wait);
if (res <= 0)
goto out_mark_dirty; goto out_mark_dirty;
spin_lock(&inode->i_lock); spin_lock(&inode->i_lock);
res = nfs_scan_commit(inode, &head, 0, 0); res = nfs_scan_commit(inode, &head, 0, 0);
@ -1454,12 +1459,14 @@ int nfs_commit_inode(struct inode *inode, int how)
int error = nfs_commit_list(inode, &head, how); int error = nfs_commit_list(inode, &head, how);
if (error < 0) if (error < 0)
return error; return error;
if (may_wait) if (!may_wait)
wait_on_bit(&NFS_I(inode)->flags, NFS_INO_COMMIT,
nfs_wait_bit_killable,
TASK_KILLABLE);
else
goto out_mark_dirty; goto out_mark_dirty;
error = wait_on_bit(&NFS_I(inode)->flags,
NFS_INO_COMMIT,
nfs_wait_bit_killable,
TASK_KILLABLE);
if (error < 0)
return error;
} else } else
nfs_commit_clear_lock(NFS_I(inode)); nfs_commit_clear_lock(NFS_I(inode));
return res; return res;