From: Trond Myklebust <Trond.Myklebust@netapp.com>
Date: Fri, 8 Sep 2006 00:09:41 +0000 (-0400)
Subject: LOCKD: Fix a deadlock in nlm_traverse_files()
X-Git-Tag: v2.6.17.14~15
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=387436208278da65b5715e0b3f96a8a3b5a4ed08;p=thirdparty%2Fkernel%2Fstable.git

LOCKD: Fix a deadlock in nlm_traverse_files()

nlm_traverse_files() is not allowed to hold the nlm_file_mutex while calling
nlm_inspect file, since it may end up calling nlm_release_file() when
releaseing the blocks.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
index a570e5c8a930f..ef9c9539727d7 100644
--- a/fs/lockd/svcsubs.c
+++ b/fs/lockd/svcsubs.c
@@ -238,19 +238,22 @@ static int
 nlm_traverse_files(struct nlm_host *host, int action)
 {
 	struct nlm_file	*file, **fp;
-	int		i;
+	int i, ret = 0;
 
 	mutex_lock(&nlm_file_mutex);
 	for (i = 0; i < FILE_NRHASH; i++) {
 		fp = nlm_files + i;
 		while ((file = *fp) != NULL) {
+			file->f_count++;
+			mutex_unlock(&nlm_file_mutex);
+
 			/* Traverse locks, blocks and shares of this file
 			 * and update file->f_locks count */
-			if (nlm_inspect_file(host, file, action)) {
-				mutex_unlock(&nlm_file_mutex);
-				return 1;
-			}
+			if (nlm_inspect_file(host, file, action))
+				ret = 1;
 
+			mutex_lock(&nlm_file_mutex);
+			file->f_count--;
 			/* No more references to this file. Let go of it. */
 			if (!file->f_blocks && !file->f_locks
 			 && !file->f_shares && !file->f_count) {
@@ -263,7 +266,7 @@ nlm_traverse_files(struct nlm_host *host, int action)
 		}
 	}
 	mutex_unlock(&nlm_file_mutex);
-	return 0;
+	return ret;
 }
 
 /*