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
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 4d686ee..55a8c36 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1261,13 +1261,17 @@
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
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))
return 1;
- if (may_wait && !out_of_line_wait_on_bit_lock(&nfsi->flags,
- NFS_INO_COMMIT, nfs_wait_bit_killable,
- TASK_KILLABLE))
- return 1;
- return 0;
+ if (!may_wait)
+ return 0;
+ ret = out_of_line_wait_on_bit_lock(&nfsi->flags,
+ NFS_INO_COMMIT,
+ nfs_wait_bit_killable,
+ TASK_KILLABLE);
+ return (ret < 0) ? ret : 1;
}
static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
@@ -1443,9 +1447,10 @@
{
LIST_HEAD(head);
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;
spin_lock(&inode->i_lock);
res = nfs_scan_commit(inode, &head, 0, 0);
@@ -1454,12 +1459,14 @@
int error = nfs_commit_list(inode, &head, how);
if (error < 0)
return error;
- if (may_wait)
- wait_on_bit(&NFS_I(inode)->flags, NFS_INO_COMMIT,
- nfs_wait_bit_killable,
- TASK_KILLABLE);
- else
+ if (!may_wait)
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
nfs_commit_clear_lock(NFS_I(inode));
return res;