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@mail.parknet.co.jp>
Reported-by: Laurent GUERBY <laurent@guerby.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 6b74d09..de0004f 100644 (file)
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -202,9 +202,9 @@ static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
        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;
 }