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authorPavel Shilovsky <pshilovsky@samba.org>2013-07-11 11:17:45 +0400
committerSteve French <smfrench@gmail.com>2013-07-12 03:05:41 +0400
commit689c3db4d57a73bee6c5ad7797fce7b54d32a87c (patch)
treec8a1f22b1fcdc1335d12a0b41889ec5098176d8b /fs/cifs
parentb33fcf1c9d359374ef6e8e7ec1e0b6f7a8717e16 (diff)
downloadlinux-689c3db4d57a73bee6c5ad7797fce7b54d32a87c.tar.xz
CIFS: Fix a deadlock when a file is reopened
If we request reading or writing on a file that needs to be reopened, it causes the deadlock: we are already holding rw semaphore for reading and then we try to acquire it for writing in cifs_relock_file. Fix this by acquiring the semaphore for reading in cifs_relock_file due to we don't make any changes in locks and don't need a write access. CC: <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org> Acked-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com>
Diffstat (limited to 'fs/cifs')
-rw-r--r--fs/cifs/file.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 1dc9dea2ae70..1e57f36ea1b2 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -561,11 +561,10 @@ cifs_relock_file(struct cifsFileInfo *cfile)
struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
int rc = 0;
- /* we are going to update can_cache_brlcks here - need a write access */
- down_write(&cinode->lock_sem);
+ down_read(&cinode->lock_sem);
if (cinode->can_cache_brlcks) {
- /* can cache locks - no need to push them */
- up_write(&cinode->lock_sem);
+ /* can cache locks - no need to relock */
+ up_read(&cinode->lock_sem);
return rc;
}
@@ -576,7 +575,7 @@ cifs_relock_file(struct cifsFileInfo *cfile)
else
rc = tcon->ses->server->ops->push_mand_locks(cfile);
- up_write(&cinode->lock_sem);
+ up_read(&cinode->lock_sem);
return rc;
}