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authorRoland Dreier <rdreier@cisco.com>2010-04-27 14:23:57 -0700
committerAl Viro <viro@zeniv.linux.org.uk>2010-05-21 18:31:22 -0400
commit51ee049e771c14a29aaee8ecd6cbbe14db088f3a (patch)
tree594c6676eb50a59ce82625ee09fee73fd700a5ed
parentcc9106247de92549e50abb0ba12d6b2fdbf0be55 (diff)
vfs: add lockdep annotation to s_vfs_rename_key for ecryptfs
> ============================================= > [ INFO: possible recursive locking detected ] > 2.6.31-2-generic #14~rbd3 > --------------------------------------------- > firefox-3.5/4162 is trying to acquire lock: > (&s->s_vfs_rename_mutex){+.+.+.}, at: [<ffffffff81139d31>] lock_rename+0x41/0xf0 > > but task is already holding lock: > (&s->s_vfs_rename_mutex){+.+.+.}, at: [<ffffffff81139d31>] lock_rename+0x41/0xf0 > > other info that might help us debug this: > 3 locks held by firefox-3.5/4162: > #0: (&s->s_vfs_rename_mutex){+.+.+.}, at: [<ffffffff81139d31>] lock_rename+0x41/0xf0 > #1: (&sb->s_type->i_mutex_key#11/1){+.+.+.}, at: [<ffffffff81139d5a>] lock_rename+0x6a/0xf0 > #2: (&sb->s_type->i_mutex_key#11/2){+.+.+.}, at: [<ffffffff81139d6f>] lock_rename+0x7f/0xf0 > > stack backtrace: > Pid: 4162, comm: firefox-3.5 Tainted: G C 2.6.31-2-generic #14~rbd3 > Call Trace: > [<ffffffff8108ae74>] print_deadlock_bug+0xf4/0x100 > [<ffffffff8108ce26>] validate_chain+0x4c6/0x750 > [<ffffffff8108d2e7>] __lock_acquire+0x237/0x430 > [<ffffffff8108d585>] lock_acquire+0xa5/0x150 > [<ffffffff81139d31>] ? lock_rename+0x41/0xf0 > [<ffffffff815526ad>] __mutex_lock_common+0x4d/0x3d0 > [<ffffffff81139d31>] ? lock_rename+0x41/0xf0 > [<ffffffff81139d31>] ? lock_rename+0x41/0xf0 > [<ffffffff8120eaf9>] ? ecryptfs_rename+0x99/0x170 > [<ffffffff81552b36>] mutex_lock_nested+0x46/0x60 > [<ffffffff81139d31>] lock_rename+0x41/0xf0 > [<ffffffff8120eb2a>] ecryptfs_rename+0xca/0x170 > [<ffffffff81139a9e>] vfs_rename_dir+0x13e/0x160 > [<ffffffff8113ac7e>] vfs_rename+0xee/0x290 > [<ffffffff8113c212>] ? __lookup_hash+0x102/0x160 > [<ffffffff8113d512>] sys_renameat+0x252/0x280 > [<ffffffff81133eb4>] ? cp_new_stat+0xe4/0x100 > [<ffffffff8101316a>] ? sysret_check+0x2e/0x69 > [<ffffffff8108c34d>] ? trace_hardirqs_on_caller+0x14d/0x190 > [<ffffffff8113d55b>] sys_rename+0x1b/0x20 > [<ffffffff81013132>] system_call_fastpath+0x16/0x1b The trace above is totally reproducible by doing a cross-directory rename on an ecryptfs directory. The issue seems to be that sys_renameat() does lock_rename() then calls into the filesystem; if the filesystem is ecryptfs, then ecryptfs_rename() again does lock_rename() on the lower filesystem, and lockdep can't tell that the two s_vfs_rename_mutexes are different. It seems an annotation like the following is sufficient to fix this (it does get rid of the lockdep trace in my simple tests); however I would like to make sure I'm not misunderstanding the locking, hence the CC list... Signed-off-by: Roland Dreier <rdreier@cisco.com> Cc: Tyler Hicks <tyhicks@linux.vnet.ibm.com> Cc: Dustin Kirkland <kirkland@canonical.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/super.c1
-rw-r--r--include/linux/fs.h1
2 files changed, 2 insertions, 0 deletions
diff --git a/fs/super.c b/fs/super.c
index 89afca5055ab..69688b15f1fa 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -88,6 +88,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
s->s_count = 1;
atomic_set(&s->s_active, 1);
mutex_init(&s->s_vfs_rename_mutex);
+ lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
mutex_init(&s->s_dquot.dqio_mutex);
mutex_init(&s->s_dquot.dqonoff_mutex);
init_rwsem(&s->s_dquot.dqptr_sem);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f3e108314c93..9626c5fbb0e1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1741,6 +1741,7 @@ struct file_system_type {
struct lock_class_key s_lock_key;
struct lock_class_key s_umount_key;
+ struct lock_class_key s_vfs_rename_key;
struct lock_class_key i_lock_key;
struct lock_class_key i_mutex_key;