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Btrfs: fix a bug of per-file nocow

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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 <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
This commit is contained in:
Liu Bo 2012-09-11 08:33:50 -06:00 committed by Chris Mason
parent 9c52057c69
commit 213490b301
2 changed files with 5 additions and 3 deletions
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3
fs/btrfs/inode.c
View File

@ -4818,8 +4818,7 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
if (S_ISREG(mode)) {
if (btrfs_test_opt(root, NODATASUM))
BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
if (btrfs_test_opt(root, NODATACOW) ||
(BTRFS_I(dir)->flags & BTRFS_INODE_NODATACOW))
if (btrfs_test_opt(root, NODATACOW))
BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
}

5
fs/btrfs/ioctl.c
View File

@ -141,8 +141,11 @@ void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
}
if (flags & BTRFS_INODE_NODATACOW)
if (flags & BTRFS_INODE_NODATACOW) {
BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
if (S_ISREG(inode->i_mode))
BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
}
btrfs_update_iflags(inode);
}