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? > > 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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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