btrfs-progs/check
Qu Wenruo 9a85b7db02 btrfs-progs: check: Initialize extent_record::generation member
[BUG]
When using `btrfs check --init-extent-tree`, there is a pretty high
chance that the result fs can't pass tree-checker:

  BTRFS critical (device dm-3): corrupt leaf: block=5390336 slot=149 extent bytenr=20115456 len=4096 invalid generation, have 16384 expect (0, 360]
  BTRFS error (device dm-3): block=5390336 read time tree block corruption detected
  BTRFS error (device dm-3): failed to read block groups: -5
  BTRFS error (device dm-3): open_ctree failed

[CAUSE]
The result fs has a pretty screwed up EXTENT_ITEMs for data extents:

        item 148 key (20111360 EXTENT_ITEM 4096) itemoff 8777 itemsize 53
                refs 1 gen 0 flags DATA
                extent data backref root FS_TREE objectid 841 offset 0 count 1
        item 149 key (20115456 EXTENT_ITEM 4096) itemoff 8724 itemsize 53
                refs 1 gen 16384 flags DATA
                extent data backref root FS_TREE objectid 906 offset 0 count 1

Kernel tree-checker will accept 0 generation, but that 16384 generation
is definitely going to trigger the alarm.

Looking into the code, it's add_extent_rec_nolookup() allocating a new
extent_rec, but not copying all members from parameter @tmpl, resulting
generation not properly initialized.

[FIX]
Just copy tmpl->generation in add_extent_rec_nolookup(). And since all
call sites have set all members of @tmpl to 0 before
add_extent_rec_nolookup(), we shouldn't get garbage values.

For the 0 generation problem, it will be solved in another patch.

Issue: #225 (Not the initial report, but extent tree rebuild result)
Reviewed-by: Su Yue <Damenly_Su@gmx.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-01-09 14:27:10 +01:00
..
common.h btrfs-progs: check: move device_record to main.c 2019-10-14 17:27:41 +02:00
main.c btrfs-progs: check: Initialize extent_record::generation member 2020-01-09 14:27:10 +01:00
mode-common.c btrfs-progs: check/lowmem: Fix a false alert on uninitialized value 2019-11-22 19:09:51 +01:00
mode-common.h btrfs-progs: check/original: Fix inode mode in subvolume trees 2019-11-18 19:21:07 +01:00
mode-lowmem.c btrfs-progs: check/lowmem: Add check and repair for invalid inode generation 2019-11-18 19:21:07 +01:00
mode-lowmem.h btrfs-progs: check/lowmem: Check and repair root generation 2019-09-04 16:06:50 +02:00
mode-original.h btrfs-progs: check/original: Add check and repair for invalid inode generation 2019-11-18 19:21:07 +01:00
qgroup-verify.c btrfs-progs: move qgroup-verify.[ch] to check/ 2019-10-14 17:27:35 +02:00
qgroup-verify.h btrfs-progs: move qgroup-verify.[ch] to check/ 2019-10-14 17:27:35 +02:00