From: Liu Bo Date: Tue, 11 Sep 2012 14:33:50 +0000 (-0600) Subject: Btrfs: fix a bug of per-file nocow X-Git-Tag: v3.8-rc1~71^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=213490b301773ea9c6fb89a86424a6901fcdd069;p=pandora-kernel.git Btrfs: fix a bug of per-file nocow Users report a bug, the reproducer is: $ mkfs.btrfs /dev/loop0 $ mount /dev/loop0 /mnt/btrfs/ $ mkdir /mnt/btrfs/dir $ chattr +C /mnt/btrfs/dir/ $ dd if=/dev/zero of=/mnt/btrfs/dir/foo bs=4K count=10; $ lsattr /mnt/btrfs/dir/foo ---------------C- /mnt/btrfs/dir/foo $ filefrag /mnt/btrfs/dir/foo /mnt/btrfs/dir/foo: 1 extent found ---> an extent $ dd if=/dev/zero of=/mnt/btrfs/dir/foo bs=4K count=1 seek=5 conv=notrunc,nocreat; sync $ filefrag /mnt/btrfs/dir/foo /mnt/btrfs/dir/foo: 3 extents found ---> with nocow, btrfs breaks the extent into three parts The new created file should not only inherit the NODATACOW flag, but also honor NODATASUM flag, because we must do COW on a file extent with checksum. Signed-off-by: Liu Bo Signed-off-by: Chris Mason --- Reading git-diff-tree failed