vfs: fix possible deadlock in ext2, ext3, ext4 when using xattrs
mb_cache_entry_alloc() was allocating cache entries with GFP_KERNEL. But
filesystems are calling this function while holding xattr_sem so possible
recursion into the fs violates locking ordering of xattr_sem and transaction
start / i_mutex for ext2-4. Change mb_cache_entry_alloc() so that filesystems
can specify desired gfp mask and use GFP_NOFS from all of them.
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Dave Jones <davej@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 3e8683d..a99d46f 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -835,7 +835,7 @@
struct mb_cache_entry *ce;
int error;
- ce = mb_cache_entry_alloc(ext2_xattr_cache);
+ ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
if (!ce)
return -ENOMEM;
error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);