3.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Pavel Shilovsky <pshilovsky@xxxxxxxxx>
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@xxxxxxxxx>
Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Steve French <smfrench@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/cifs/file.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -557,11 +557,10 @@ cifs_relock_file(struct cifsFileInfo *cf
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;
}
@@ -572,7 +571,7 @@ cifs_relock_file(struct cifsFileInfo *cf
else
rc = tcon->ses->server->ops->push_mand_locks(cfile);
- up_write(&cinode->lock_sem);
+ up_read(&cinode->lock_sem);
return rc;
}
--
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