Btrfs: fix lockdep warning about log_mutex
While checking INODE_REF/INODE_EXTREF for a corner case, we may acquire a
different inode's log_mutex with holding the current inode's log_mutex, and
lockdep has complained this with a possilble deadlock warning.
Fix this by using mutex_lock_nested() when processing the other inode's
log_mutex.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index f10bf52..eeffff8 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -37,6 +37,7 @@
*/
#define LOG_INODE_ALL 0
#define LOG_INODE_EXISTS 1
+#define LOG_OTHER_INODE 2
/*
* directory trouble cases
@@ -4641,7 +4642,7 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
if (S_ISDIR(inode->i_mode) ||
(!test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
&BTRFS_I(inode)->runtime_flags) &&
- inode_only == LOG_INODE_EXISTS))
+ inode_only >= LOG_INODE_EXISTS))
max_key.type = BTRFS_XATTR_ITEM_KEY;
else
max_key.type = (u8)-1;
@@ -4665,7 +4666,13 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
return ret;
}
- mutex_lock(&BTRFS_I(inode)->log_mutex);
+ if (inode_only == LOG_OTHER_INODE) {
+ inode_only = LOG_INODE_EXISTS;
+ mutex_lock_nested(&BTRFS_I(inode)->log_mutex,
+ SINGLE_DEPTH_NESTING);
+ } else {
+ mutex_lock(&BTRFS_I(inode)->log_mutex);
+ }
/*
* a brute force approach to making sure we get the most uptodate
@@ -4817,7 +4824,7 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
* unpin it.
*/
err = btrfs_log_inode(trans, root, other_inode,
- LOG_INODE_EXISTS,
+ LOG_OTHER_INODE,
0, LLONG_MAX, ctx);
iput(other_inode);
if (err)