[PATCH] NLM: Fix the NLM_GRANTED callback checks

If 2 threads attached to the same process are blocking on different locks on
different files (maybe even on different servers) but have the same lock
arguments (i.e.  same offset+length - actually quite common, since most
processes try to lock the entire file) then the first GRANTED call that wakes
one up will also wake the other.

Currently when the NLM_GRANTED callback comes in, lockd walks the list of
blocked locks in search of a match to the lock that the NLM server has
granted.  Although it checks the lock pid, start and end, it fails to check
the filehandle and the server address.

By checking the filehandle and server IP address, we ensure that this only
happens if the locks truly are referencing the same file.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 17 insertions, 10 deletions

diff --git a/fs/lockd/clntlock.c b/fs/lockd/clntlock.c
index 3eaf6e7..da6354b 100644
--- a/fs/lockd/clntlock.c
+++ b/fs/lockd/clntlock.c
@@ -111,9 +111,10 @@ long nlmclnt_block(struct nlm_rqst *req, long timeout)
 /*
  * The server lockd has called us back to tell us the lock was granted
  */
-u32
-nlmclnt_grant(struct nlm_lock *lock)
+u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
 {
+	const struct file_lock *fl = &lock->fl;
+	const struct nfs_fh *fh = &lock->fh;
 	struct nlm_wait	*block;
 	u32 res = nlm_lck_denied;
 
@@ -122,14 +123,20 @@ nlmclnt_grant(struct nlm_lock *lock)
 	 * Warning: must not use cookie to match it!
 	 */
 	list_for_each_entry(block, &nlm_blocked, b_list) {
-		if (nlm_compare_locks(block->b_lock, &lock->fl)) {
-			/* Alright, we found a lock. Set the return status
-			 * and wake up the caller
-			 */
-			block->b_status = NLM_LCK_GRANTED;
-			wake_up(&block->b_wait);
-			res = nlm_granted;
-		}
+		struct file_lock *fl_blocked = block->b_lock;
+
+		if (!nlm_compare_locks(fl_blocked, fl))
+			continue;
+		if (!nlm_cmp_addr(&block->b_host->h_addr, addr))
+			continue;
+		if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_dentry->d_inode) ,fh) != 0)
+			continue;
+		/* Alright, we found a lock. Set the return status
+		 * and wake up the caller
+		 */
+		block->b_status = NLM_LCK_GRANTED;
+		wake_up(&block->b_wait);
+		res = nlm_granted;
 	}
 	return res;
 }