[02/13--revised] vfs: don't use PARENT/CHILD lock classes for non-directories

Commit Message

J. Bruce Fields Sept. 12, 2013, 3:16 a.m. UTC

From: "J. Bruce Fields" <[e-mail]>

Reserve I_MUTEX_PARENT and I_MUTEX_CHILD for locking of actual
directories.

(Also I_MUTEX_QUOTA isn't really a meaningful name for this locking
class any more; fixed in a later patch.)

Acked-by: Jeff Layton <[e-mail]>
Signed-off-by: J. Bruce Fields <[e-mail]>
---
 fs/inode.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

> Argh, apologies!  Revising this patch at one point I forgot to fix up
> one line, and I somehow overlooked the resulting lockdep warning till
> just now.

So the revised patch looks like this.

Patch

diff --git a/fs/inode.c b/fs/inode.c
index 20750b0..a8a8ded 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -990,16 +990,16 @@  void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
 {
 	WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
 	if (inode1 == inode2 || !inode2) {
-		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
+		mutex_lock(&inode1->i_mutex);
 		return;
 	}
 	WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
 	if (inode1 < inode2) {
-		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
-		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
+		mutex_lock(&inode1->i_mutex);
+		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_QUOTA);
 	} else {
-		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
-		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
+		mutex_lock(&inode2->i_mutex);
+		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_QUOTA);
 	}
 }
 EXPORT_SYMBOL(lock_two_nondirectories);