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authorScott Mayhew <smayhew@redhat.com>2014-01-17 15:12:05 -0500
committerTrond Myklebust <trond.myklebust@primarydata.com>2014-01-17 15:37:15 -0500
commit263b4509ec4d47e0da3e753f85a39ea12d1eff24 (patch)
treeca771569ace5c365f6c5e0c348dbc615f552a499 /fs/nfs/write.c
parenta9ab5e840669b19aca2974e2c771a77df2876434 (diff)
nfs: always make sure page is up-to-date before extending a write to cover the entire page
We should always make sure the cached page is up-to-date when we're determining whether we can extend a write to cover the full page -- even if we've received a write delegation from the server. Commit c7559663 added logic to skip this check if we have a write delegation, which can lead to data corruption such as the following scenario if client B receives a write delegation from the NFS server: Client A: # echo 123456789 > /mnt/file Client B: # echo abcdefghi >> /mnt/file # cat /mnt/file 0�D0�abcdefghi Just because we hold a write delegation doesn't mean that we've read in the entire page contents. Cc: <stable@vger.kernel.org> # v3.11+ Signed-off-by: Scott Mayhew <smayhew@redhat.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'fs/nfs/write.c')
-rw-r--r--fs/nfs/write.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 77a00c66c7d9..a44a87268a6e 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -922,19 +922,20 @@ out:
* extend the write to cover the entire page in order to avoid fragmentation
* inefficiencies.
*
- * If the file is opened for synchronous writes or if we have a write delegation
- * from the server then we can just skip the rest of the checks.
+ * If the file is opened for synchronous writes then we can just skip the rest
+ * of the checks.
*/
static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
{
if (file->f_flags & O_DSYNC)
return 0;
+ if (!nfs_write_pageuptodate(page, inode))
+ return 0;
if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
return 1;
- if (nfs_write_pageuptodate(page, inode) && (inode->i_flock == NULL ||
- (inode->i_flock->fl_start == 0 &&
+ if (inode->i_flock == NULL || (inode->i_flock->fl_start == 0 &&
inode->i_flock->fl_end == OFFSET_MAX &&
- inode->i_flock->fl_type != F_RDLCK)))
+ inode->i_flock->fl_type != F_RDLCK))
return 1;
return 0;
}