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Btrfs: cleanup BUG_ON in merge_bio

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One can use btrfs-corrupt-block to hit BUG_ON() in merge_bio(),
thus this aims to stop anyone to panic the whole system by using
 their btrfs.

Since the error in merge_bio can only come from __btrfs_map_block()
when chunk tree mapping has something insane and __btrfs_map_block()
has already had printed the reason, we can just return errors in
merge_bio.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Liu Bo 2016-06-22 18:31:49 -07:00 committed by David Sterba
parent fba4b69771
commit 6f034ece34
2 changed files with 6 additions and 3 deletions
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1
fs/btrfs/extent_io.c
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@ -2756,7 +2756,6 @@ static int merge_bio(int rw, struct extent_io_tree *tree, struct page *page,
if (tree->ops && tree->ops->merge_bio_hook)
ret = tree->ops->merge_bio_hook(rw, page, offset, size, bio,
bio_flags);
BUG_ON(ret < 0);
return ret;
}

8
fs/btrfs/inode.c
View File

@ -1822,6 +1822,10 @@ static void btrfs_clear_bit_hook(struct inode *inode,
/*
* extent_io.c merge_bio_hook, this must check the chunk tree to make sure
* we don't create bios that span stripes or chunks
*
* return 1 if page cannot be merged to bio
* return 0 if page can be merged to bio
* return error otherwise
*/
int btrfs_merge_bio_hook(int rw, struct page *page, unsigned long offset,
size_t size, struct bio *bio,
@ -1840,8 +1844,8 @@ int btrfs_merge_bio_hook(int rw, struct page *page, unsigned long offset,
map_length = length;
ret = btrfs_map_block(root->fs_info, rw, logical,
&map_length, NULL, 0);
/* Will always return 0 with map_multi == NULL */
BUG_ON(ret < 0);
if (ret < 0)
return ret;
if (map_length < length + size)
return 1;
return 0;