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    Btrfs: do not bother to defrag an extent if it is a big real extent · 66c26892
    Liu Bo 提交于
    $ mkfs.btrfs /dev/sdb7
    $ mount /dev/sdb7 /mnt/btrfs/ -oautodefrag
    $ dd if=/dev/zero of=/mnt/btrfs/foobar bs=4k count=10 oflag=direct 2>/dev/null
    $ filefrag -v /mnt/btrfs/foobar
    Filesystem type is: 9123683e
    File size of /mnt/btrfs/foobar is 40960 (10 blocks, blocksize 4096)
     ext logical physical expected length flags
       0       0     3072              10 eof
    /mnt/btrfs/foobar: 1 extent found
    
    Now we have a big real extent [0, 40960), but autodefrag will still defrag it.
    
    $ sync
    $ filefrag -v /mnt/btrfs/foobar
    Filesystem type is: 9123683e
    File size of /mnt/btrfs/foobar is 40960 (10 blocks, blocksize 4096)
     ext logical physical expected length flags
       0       0     3082              10 eof
    /mnt/btrfs/foobar: 1 extent found
    
    So if we already find a big real extent, we're ok about that, just skip it.
    Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>
    Signed-off-by: NChris Mason <chris.mason@oracle.com>
    66c26892
ioctl.c 81.0 KB