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authorPavel Shilovsky <pshilovsky@samba.org>2013-07-11 11:17:45 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-07-21 18:21:21 -0700
commit059a1671f28c977fe69a0f86eeb0fa2084fdb3dd (patch)
treed3f051c00845f9d840bca3b1d6d98a637713e958 /fs/cifs
parentcfe24e4e36ec19a56bac17691f8721ac44050a6f (diff)
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CIFS: Fix a deadlock when a file is reopened
commit 689c3db4d57a73bee6c5ad7797fce7b54d32a87c upstream. 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. Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org> Acked-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 48b29d24c9f..c2934f8701d 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -553,11 +553,10 @@ 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;
}
@@ -568,7 +567,7 @@ 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;
}