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https://github.com/kdave/btrfs-progs
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8d45dc270a
[BUG]
When using `btrfs check --init-extent-tree`, we will create incorrect
generation number for data extents in extent tree:
item 10 key (13631488 EXTENT_ITEM 1048576) itemoff 15828 itemsize 53
refs 1 gen 0 flags DATA
extent data backref root FS_TREE objectid 257 offset 0 count 1
[CAUSE]
Since data extent generation is not as obvious as tree blocks, which has
header containing its generations, so for data extents, its
extent_record::generation is not really updated, resulting such 0
generation.
[FIX]
To get generation of a data extent, there are two sources we can rely:
- EXTENT_ITEM
There is always a btrfs_extent_item::generation can be utilized.
Although this is not possible for --init-extent-tree use case.
- EXTENT_DATA
We have btrfs_file_extent_item::generation for regular and
preallocated data extents.
Since --init-extent-tree will go through subvolume trees, this would
be the main source for extent data generation.
Then we only need to make add_data_backref() to accept @gen parameter,
and pass it down to extent_record structure.
And for the final extent item generation update, here we add extra
fallback values, if we can't find FILE_EXTENT items.
In that case, we just fall back to current transid.
With this modification, recreated data EXTENT_ITEM now has correct
generation number:
item 10 key (13631488 EXTENT_ITEM 1048576) itemoff 15828 itemsize 53
refs 1 gen 6 flags DATA
extent data backref root FS_TREE objectid 257 offset 0 count 1
Reviewed-by: Su Yue <Damenly_Su@gmx.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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|---|---|---|
| .. | ||
| common.h | ||
| main.c | ||
| mode-common.c | ||
| mode-common.h | ||
| mode-lowmem.c | ||
| mode-lowmem.h | ||
| mode-original.h | ||
| qgroup-verify.c | ||
| qgroup-verify.h | ||