Commit 335e92e8 authored by Jan Kara's avatar Jan Kara Committed by Linus Torvalds
Browse files

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: default avatarJan Kara <jack@suse.cz>
Reported-by: default avatarDave Jones <davej@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 423bec43

fs/ext2/xattr.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -835,7 +835,7 @@ ext2_xattr_cache_insert(struct buffer_head *bh) 
	struct mb_cache_entry *ce;

	struct mb_cache_entry *ce;

	int error;

	int error;





	ce = mb_cache_entry_alloc(ext2_xattr_cache);

	ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);

	if (!ce)

	if (!ce)

		return -ENOMEM;

		return -ENOMEM;

	error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);

	error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);

fs/ext3/xattr.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -1126,7 +1126,7 @@ ext3_xattr_cache_insert(struct buffer_head *bh) 
	struct mb_cache_entry *ce;

	struct mb_cache_entry *ce;

	int error;

	int error;





	ce = mb_cache_entry_alloc(ext3_xattr_cache);

	ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);

	if (!ce) {

	if (!ce) {

		ea_bdebug(bh, "out of memory");

		ea_bdebug(bh, "out of memory");

		return;

		return;

fs/ext4/xattr.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -1386,7 +1386,7 @@ ext4_xattr_cache_insert(struct buffer_head *bh) 
	struct mb_cache_entry *ce;

	struct mb_cache_entry *ce;

	int error;

	int error;





	ce = mb_cache_entry_alloc(ext4_xattr_cache);

	ce = mb_cache_entry_alloc(ext4_xattr_cache, GFP_NOFS);

	if (!ce) {

	if (!ce) {

		ea_bdebug(bh, "out of memory");

		ea_bdebug(bh, "out of memory");

		return;

		return;

fs/mbcache.c

+2 −2
Original line number Original line Diff line number Diff line
@@ -399,11 +399,11 @@ mb_cache_destroy(struct mb_cache *cache) 
 * if no more memory was available.

 * if no more memory was available.

 */

 */

struct mb_cache_entry *

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;

	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) {

	if (ce) {

		atomic_inc(&cache->c_entry_count);

		atomic_inc(&cache->c_entry_count);

		INIT_LIST_HEAD(&ce->e_lru_list);

		INIT_LIST_HEAD(&ce->e_lru_list);

include/linux/mbcache.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -34,7 +34,7 @@ void mb_cache_destroy(struct mb_cache *); 




/* Functions on cache entries */

/* 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 *,

int mb_cache_entry_insert(struct mb_cache_entry *, struct block_device *,

			  sector_t, unsigned int[]);

			  sector_t, unsigned int[]);

void mb_cache_entry_release(struct mb_cache_entry *);

void mb_cache_entry_release(struct mb_cache_entry *);

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