Qu Wenruo 於 2018-03-07 17:27 寫到:
On 2018年03月07日 16:20, robbieko wrote:
From: Robbie Ko <robbi...@synology.com>
This patchset intends to fix btrfs fiemap related bug.
The fiemap has the following problems:
1) Wrong extent count when fm_extent_count is zero.
2) SHARED bit is not correct
I have two ideas, but I do not know which one is the best.
Like:
# dd if=/dev/zero bs=16K count=2 oflag=dsync of=/mnt/btrfs/file
# xfs_io -c "fiemap -v" /mnt/btrfs/file
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..63]: 4241424..4241487 64 0x1
# cloner -s $((16*1024)) /mnt/btrfs/file /mnt/btrfs/file_clone
1. When any extent is shared in extent map, the entire extent map is
shared
# xfs_io -c "fiemap -v" /mnt/btrfs/file
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..63]: 4241424..4241487 64 0x2001
I think this is what btrfs is doing right now.
Although I'm not sure if this is the best solution.
BTW, I just did the same operation, and just get the SHARED flag on
both
source and destination.
Is there something wrong?
Currently, only the first extent is checked for shared in extent_map.
Details can refer to "[PATCH 2/2] Btrfs: fix fiemap extent SHARED flag
error with range clone."
2. Split into different extent
# xfs_io -c "fiemap -v" /mnt/btrfs/file
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..31]: 4241424..4241455 32 0x0
1: [32..63]: 4241456..4241487 32 0x2001
This is what XFS does.
Thanks,
Qu
Robbie Ko (2):
Btrfs: fiemap: pass correct bytenr when fm_extent_count is zero
Btrfs: fix fiemap extent SHARED flag error with range clone.
fs/btrfs/extent_io.c | 150
++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 132 insertions(+), 18 deletions(-)
--
1.9.1
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