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);
diff --git a/fs/ext3/xattr.c b/fs/ext3/xattr.c
index a6ea4d6..4285654 100644
--- a/fs/ext3/xattr.c
+++ b/fs/ext3/xattr.c
@@ -1126,7 +1126,7 @@
struct mb_cache_entry *ce;
int error;
- ce = mb_cache_entry_alloc(ext3_xattr_cache);
+ ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
if (!ce) {
ea_bdebug(bh, "out of memory");
return;
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index d796213..e9054c1 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1386,7 +1386,7 @@
struct mb_cache_entry *ce;
int error;
- ce = mb_cache_entry_alloc(ext4_xattr_cache);
+ ce = mb_cache_entry_alloc(ext4_xattr_cache, GFP_NOFS);
if (!ce) {
ea_bdebug(bh, "out of memory");
return;
diff --git a/fs/mbcache.c b/fs/mbcache.c
index eb31b73..ec88ff3 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -399,11 +399,11 @@
* if no more memory was available.
*/
struct mb_cache_entry *
-mb_cache_entry_alloc(struct mb_cache *cache)
+mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags)
{
struct mb_cache_entry *ce;
- ce = kmem_cache_alloc(cache->c_entry_cache, GFP_KERNEL);
+ ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
if (ce) {
atomic_inc(&cache->c_entry_count);
INIT_LIST_HEAD(&ce->e_lru_list);