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authorJ. Bruce Fields <bfields@citi.umich.edu>2009-02-04 17:35:38 -0500
committerJ. Bruce Fields <bfields@citi.umich.edu>2009-02-09 13:19:46 -0500
commit9d9b87c1218be78ddecbc85ec3bb91c79c1d56ab (patch)
treee33e637f4fa8b4dd1946c6a29e290078d34a388c /fs/lockd/svclock.c
parenteda58a85ec3fc05855a26654d97a2b53f0e715b9 (diff)
downloadlinux-9d9b87c1218be78ddecbc85ec3bb91c79c1d56ab.tar.gz
lockd: fix regression in lockd's handling of blocked locks
If a client requests a blocking lock, is denied, then requests it again,
then here in nlmsvc_lock() we will call vfs_lock_file() without FL_SLEEP
set, because we've already queued a block and don't need the locks code
to do it again.

But that means vfs_lock_file() will return -EAGAIN instead of
FILE_LOCK_DENIED.  So we still need to translate that -EAGAIN return
into a nlm_lck_blocked error in this case, and put ourselves back on
lockd's block list.

The bug was introduced by bde74e4bc64415b1 "locks: add special return
value for asynchronous locks".

Thanks to Frank van Maarseveen for the report; his original test
case was essentially

	for i in `seq 30`; do flock /nfsmount/foo sleep 10 & done

Tested-by: Frank van Maarseveen <frankvm@frankvm.com>
Reported-by: Frank van Maarseveen <frankvm@frankvm.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Diffstat (limited to 'fs/lockd/svclock.c')
-rw-r--r--fs/lockd/svclock.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 6063a8e4b9f3..763b78a6e9de 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -427,7 +427,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 			goto out;
 		case -EAGAIN:
 			ret = nlm_lck_denied;
-			goto out;
+			break;
 		case FILE_LOCK_DEFERRED:
 			if (wait)
 				break;
@@ -443,6 +443,10 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 			goto out;
 	}
 
+	ret = nlm_lck_denied;
+	if (!wait)
+		goto out;
+
 	ret = nlm_lck_blocked;
 
 	/* Append to list of blocked */