[PATCH] Fix _fat_bmap() locking

On swapon() path, it has already i_mutex. So, this uses i_alloc_sem
instead of it.

Signed-off-by: OGAWA Hirofumi <hirofumi [at] mail>
---

fs/fat/inode.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- linux-2.6.28/fs/fat/inode.c
+++ linux-2.6.28/fs/fat/inode.c
@@ -202,9 +202,9 @@
 	sector_t blocknr;
 
 	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
-	mutex_lock(&mapping->host->i_mutex);
+	down_read(&mapping->host->i_alloc_sem);
 	blocknr = generic_block_bmap(mapping, block, fat_get_block);
-	mutex_unlock(&mapping->host->i_mutex);
+	up_read(&mapping->host->i_alloc_sem);
 
 	return blocknr;
 }