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authorPavel Shilovsky <piastry@etersoft.ru>2012-03-28 21:56:19 +0400
committerSteve French <sfrench@us.ibm.com>2012-04-01 13:54:27 -0500
commit66189be74ff5f9f3fd6444315b85be210d07cef2 (patch)
tree7a179ddd7e233668dbb108faf847ceb768d2e92c
parent9ebb389d0a03b4415fe9014f6922a2412cb1109c (diff)
CIFS: Fix VFS lock usage for oplocked files
We can deadlock if we have a write oplock and two processes use the same file handle. In this case the first process can't unlock its lock if the second process blocked on the lock in the same time. Fix it by using posix_lock_file rather than posix_lock_file_wait under cinode->lock_mutex. If we request a blocking lock and posix_lock_file indicates that there is another lock that prevents us, wait untill that lock is released and restart our call. Cc: stable@kernel.org Acked-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru> Signed-off-by: Steve French <sfrench@us.ibm.com>
-rw-r--r--fs/cifs/file.c10
-rw-r--r--fs/locks.c3
-rw-r--r--include/linux/fs.h5
3 files changed, 16 insertions, 2 deletions
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 460d87b7cda..fae765dac93 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -835,13 +835,21 @@ cifs_posix_lock_set(struct file *file, struct file_lock *flock)
if ((flock->fl_flags & FL_POSIX) == 0)
return rc;
+try_again:
mutex_lock(&cinode->lock_mutex);
if (!cinode->can_cache_brlcks) {
mutex_unlock(&cinode->lock_mutex);
return rc;
}
- rc = posix_lock_file_wait(file, flock);
+
+ rc = posix_lock_file(file, flock, NULL);
mutex_unlock(&cinode->lock_mutex);
+ if (rc == FILE_LOCK_DEFERRED) {
+ rc = wait_event_interruptible(flock->fl_wait, !flock->fl_next);
+ if (!rc)
+ goto try_again;
+ locks_delete_block(flock);
+ }
return rc;
}
diff --git a/fs/locks.c b/fs/locks.c
index 637694bf3a0..0d68f1f8179 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -510,12 +510,13 @@ static void __locks_delete_block(struct file_lock *waiter)
/*
*/
-static void locks_delete_block(struct file_lock *waiter)
+void locks_delete_block(struct file_lock *waiter)
{
lock_flocks();
__locks_delete_block(waiter);
unlock_flocks();
}
+EXPORT_SYMBOL(locks_delete_block);
/* Insert waiter into blocker's block list.
* We use a circular list so that processes can be easily woken up in
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 135693e79f2..528611843ba 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1215,6 +1215,7 @@ extern int vfs_setlease(struct file *, long, struct file_lock **);
extern int lease_modify(struct file_lock **, int);
extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
+extern void locks_delete_block(struct file_lock *waiter);
extern void lock_flocks(void);
extern void unlock_flocks(void);
#else /* !CONFIG_FILE_LOCKING */
@@ -1359,6 +1360,10 @@ static inline int lock_may_write(struct inode *inode, loff_t start,
return 1;
}
+static inline void locks_delete_block(struct file_lock *waiter)
+{
+}
+
static inline void lock_flocks(void)
{
}