ext3: fix chain verification in ext3_get_blocks()
Jan Kara [Wed, 17 Jun 2009 23:26:23 +0000 (16:26 -0700)]
Chain verification in ext3_get_blocks() has been hosed since it called
verify_chain(chain, NULL) which always returns success.  As a result
readers could in theory race with truncate.  On the other hand the race
probably cannot happen with the current locking scheme, since by the
time ext3_truncate() is called all the pages are already removed and
hence get_block() shouldn't be called on such pages...

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ext3/inode.c

index b0248c6..253c2cd 100644 (file)
@@ -820,7 +820,7 @@ int ext3_get_blocks_handle(handle_t *handle, struct inode *inode,
                while (count < maxblocks && count <= blocks_to_boundary) {
                        ext3_fsblk_t blk;
 
-                       if (!verify_chain(chain, partial)) {
+                       if (!verify_chain(chain, chain + depth - 1)) {
                                /*
                                 * Indirect block might be removed by
                                 * truncate while we were reading it.