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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>
master
Jan Kara 14 years ago
committed by Linus Torvalds
parent
commit
335e92e8a5
  1. 2
      fs/ext2/xattr.c
  2. 2
      fs/ext3/xattr.c
  3. 2
      fs/ext4/xattr.c
  4. 4
      fs/mbcache.c
  5. 2
      include/linux/mbcache.h

2
fs/ext2/xattr.c

@ -835,7 +835,7 @@ ext2_xattr_cache_insert(struct buffer_head *bh)
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);

2
fs/ext3/xattr.c

@ -1126,7 +1126,7 @@ ext3_xattr_cache_insert(struct buffer_head *bh)
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;

2
fs/ext4/xattr.c

@ -1386,7 +1386,7 @@ ext4_xattr_cache_insert(struct buffer_head *bh)
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;

4
fs/mbcache.c

@ -399,11 +399,11 @@ mb_cache_destroy(struct mb_cache *cache)
* 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);

2
include/linux/mbcache.h

@ -34,7 +34,7 @@ void mb_cache_destroy(struct mb_cache *);
/* Functions on cache entries */
struct mb_cache_entry *mb_cache_entry_alloc(struct mb_cache *);
struct mb_cache_entry *mb_cache_entry_alloc(struct mb_cache *, gfp_t);
int mb_cache_entry_insert(struct mb_cache_entry *, struct block_device *,
sector_t, unsigned int[]);
void mb_cache_entry_release(struct mb_cache_entry *);

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