fat: Fix _fat_bmap() race
fat_get_cluster() assumes the requested blocknr isn't truncated during
read. _fat_bmap() doesn't follow this rule.
This protects it by ->i_mutex.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 0da04e6..be88208 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -199,7 +199,14 @@
static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
{
- return generic_block_bmap(mapping, block, fat_get_block);
+ sector_t blocknr;
+
+ /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
+ mutex_lock(&mapping->host->i_mutex);
+ blocknr = generic_block_bmap(mapping, block, fat_get_block);
+ mutex_unlock(&mapping->host->i_mutex);
+
+ return blocknr;
}
static const struct address_space_operations fat_aops = {