btrfs-progs/check/mode-common.h
Filipe Manana 457a288cb5 Btrfs-progs: check, fix false error reports for shared prealloc extents
Under some cases the filesystem checker reports an error when it finds
checksum items for an extent that is referenced by an inode as a prealloc
extent. Such cases are not an error when the extent is actually shared
(was cloned/reflinked) with other inodes and was written through one of
those other inodes.

Example:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt

  $ touch /mnt/foo
  $ xfs_io -c "falloc 0 256K" /mnt/foo
  $ sync

  $ xfs_io -c "pwrite -S 0xab 0 256K" /mnt/foo
  $ touch /mnt/bar
  $ xfs_io -c "reflink /mnt/foo 0 0 256K" /mnt/bar
  $ xfs_io -c "fsync" /mnt/bar

  <power fail>
  $ mount /dev/sdb /mnt
  $ umount /mnt

  $ btrfs check /dev/sdc
  Checking filesystem on /dev/sdb
  UUID: 52d3006e-ee3b-40eb-aa21-e56253a03d39
  checking extents
  checking free space cache
  checking fs roots
  root 5 inode 257 errors 800, odd csum item
  ERROR: errors found in fs roots
  found 688128 bytes used, error(s) found
  total csum bytes: 256
  total tree bytes: 163840
  total fs tree bytes: 65536
  total extent tree bytes: 16384
  btree space waste bytes: 138819
  file data blocks allocated: 10747904
   referenced 10747904
  $ echo $?
  1

So teach check to not report such cases as errors by checking if the
extent is shared with other inodes and if so, consider it an error the
existence of checksum items only if all those other inodes are referencing
the extent as a prealloc extent.
This case can be hit often when running the generic/475 testcase from
fstests.

A test case will follow in a separate patch.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-03-30 22:15:54 +02:00

103 lines
3.3 KiB
C

/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
/*
* Defines and function declarations for code shared by both lowmem and
* original mode
*/
#ifndef __BTRFS_CHECK_MODE_COMMON_H__
#define __BTRFS_CHECK_MODE_COMMON_H__
#include <sys/stat.h>
#include "ctree.h"
/*
* Use for tree walk to walk through trees whose leaves/nodes can be shared
* between different trees. (Namely subvolume/fs trees)
*/
struct node_refs {
u64 bytenr[BTRFS_MAX_LEVEL];
u64 refs[BTRFS_MAX_LEVEL];
int need_check[BTRFS_MAX_LEVEL];
/* field for checking all trees */
int checked[BTRFS_MAX_LEVEL];
/* the corresponding extent should be marked as full backref or not */
int full_backref[BTRFS_MAX_LEVEL];
};
extern u64 bytes_used;
extern u64 total_csum_bytes;
extern u64 total_btree_bytes;
extern u64 total_fs_tree_bytes;
extern u64 total_extent_tree_bytes;
extern u64 btree_space_waste;
extern u64 data_bytes_allocated;
extern u64 data_bytes_referenced;
extern struct list_head duplicate_extents;
extern struct list_head delete_items;
extern int no_holes;
extern int init_extent_tree;
extern int check_data_csum;
extern struct btrfs_fs_info *global_info;
extern struct task_ctx ctx;
extern struct cache_tree *roots_info_cache;
static inline u8 imode_to_type(u32 imode)
{
#define S_SHIFT 12
static unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = {
[S_IFREG >> S_SHIFT] = BTRFS_FT_REG_FILE,
[S_IFDIR >> S_SHIFT] = BTRFS_FT_DIR,
[S_IFCHR >> S_SHIFT] = BTRFS_FT_CHRDEV,
[S_IFBLK >> S_SHIFT] = BTRFS_FT_BLKDEV,
[S_IFIFO >> S_SHIFT] = BTRFS_FT_FIFO,
[S_IFSOCK >> S_SHIFT] = BTRFS_FT_SOCK,
[S_IFLNK >> S_SHIFT] = BTRFS_FT_SYMLINK,
};
return btrfs_type_by_mode[(imode & S_IFMT) >> S_SHIFT];
#undef S_SHIFT
}
static inline int fs_root_objectid(u64 objectid)
{
if (objectid == BTRFS_TREE_RELOC_OBJECTID ||
objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
return 1;
return is_fstree(objectid);
}
int check_prealloc_extent_written(struct btrfs_fs_info *fs_info,
u64 disk_bytenr, u64 num_bytes);
int count_csum_range(struct btrfs_fs_info *fs_info, u64 start,
u64 len, u64 *found);
int insert_inode_item(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 ino, u64 size,
u64 nbytes, u64 nlink, u32 mode);
int link_inode_to_lostfound(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
u64 ino, char *namebuf, u32 name_len,
u8 filetype, u64 *ref_count);
void check_dev_size_alignment(u64 devid, u64 total_bytes, u32 sectorsize);
void reada_walk_down(struct btrfs_root *root, struct extent_buffer *node,
int slot);
int check_child_node(struct extent_buffer *parent, int slot,
struct extent_buffer *child);
void reset_cached_block_groups(struct btrfs_fs_info *fs_info);
#endif