Commit 4e9845ef authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

Btrfs: tree-checker: detect file extent items with overlapping ranges 



Having file extent items with ranges that overlap each other is a
serious issue that leads to all sorts of corruptions and crashes (like a
BUG_ON() during the course of __btrfs_drop_extents() when it traims file
extent items). Therefore teach the tree checker to detect such cases.
This is motivated by a recently fixed bug (race between ranged full
fsync and writeback or adjacent ranges).

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 0c713cba

fs/btrfs/tree-checker.c

+45 −4
Original line number Diff line number Diff line
@@ -107,8 +107,26 @@ static void file_extent_err(const struct extent_buffer *eb, int slot, 
	(!IS_ALIGNED(btrfs_file_extent_##name((leaf), (fi)), (alignment)));   \

})



static u64 file_extent_end(struct extent_buffer *leaf,

			   struct btrfs_key *key,

			   struct btrfs_file_extent_item *extent)

{

	u64 end;

	u64 len;



	if (btrfs_file_extent_type(leaf, extent) == BTRFS_FILE_EXTENT_INLINE) {

		len = btrfs_file_extent_ram_bytes(leaf, extent);

		end = ALIGN(key->offset + len, leaf->fs_info->sectorsize);

	} else {

		len = btrfs_file_extent_num_bytes(leaf, extent);

		end = key->offset + len;

	}

	return end;

}



static int check_extent_data_item(struct extent_buffer *leaf,

				  struct btrfs_key *key, int slot)

				  struct btrfs_key *key, int slot,

				  struct btrfs_key *prev_key)

{

	struct btrfs_fs_info *fs_info = leaf->fs_info;

	struct btrfs_file_extent_item *fi;
@@ -188,6 +206,28 @@ static int check_extent_data_item(struct extent_buffer *leaf, 
	    CHECK_FE_ALIGNED(leaf, slot, fi, offset, sectorsize) ||

	    CHECK_FE_ALIGNED(leaf, slot, fi, num_bytes, sectorsize))

		return -EUCLEAN;



	/*

	 * Check that no two consecutive file extent items, in the same leaf,

	 * present ranges that overlap each other.

	 */

	if (slot > 0 &&

	    prev_key->objectid == key->objectid &&

	    prev_key->type == BTRFS_EXTENT_DATA_KEY) {

		struct btrfs_file_extent_item *prev_fi;

		u64 prev_end;



		prev_fi = btrfs_item_ptr(leaf, slot - 1,

					 struct btrfs_file_extent_item);

		prev_end = file_extent_end(leaf, prev_key, prev_fi);

		if (prev_end > key->offset) {

			file_extent_err(leaf, slot - 1,

"file extent end range (%llu) goes beyond start offset (%llu) of the next file extent",

					prev_end, key->offset);

			return -EUCLEAN;

		}

	}



	return 0;

}
@@ -774,14 +814,15 @@ static int check_inode_item(struct extent_buffer *leaf, 
 * Common point to switch the item-specific validation.

 */

static int check_leaf_item(struct extent_buffer *leaf,

			   struct btrfs_key *key, int slot)

			   struct btrfs_key *key, int slot,

			   struct btrfs_key *prev_key)

{

	int ret = 0;

	struct btrfs_chunk *chunk;



	switch (key->type) {

	case BTRFS_EXTENT_DATA_KEY:

		ret = check_extent_data_item(leaf, key, slot);

		ret = check_extent_data_item(leaf, key, slot, prev_key);

		break;

	case BTRFS_EXTENT_CSUM_KEY:

		ret = check_csum_item(leaf, key, slot);
@@ -928,7 +969,7 @@ static int check_leaf(struct extent_buffer *leaf, bool check_item_data) 
			 * Check if the item size and content meet other

			 * criteria

			 */

			ret = check_leaf_item(leaf, &key, slot);

			ret = check_leaf_item(leaf, &key, slot, &prev_key);

			if (ret < 0)

				return ret;

		}

CRA Git | Maintained and supported by SUSTech CRA and CCSE