On Fri, Aug 31, 2012 at 01:36:54PM +0800, Liu Bo wrote:
> 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.
I was not entierly correct when suggesting to move NODATASUM to
inherit_iflags. Se below.
>
> Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
> ---
> fs/btrfs/inode.c | 3 +--
> fs/btrfs/ioctl.c | 3 ++-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index b2c3514..9bce6e9 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -4720,8 +4720,7 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
> if (S_ISREG(mode)) {
Originaly it applied to regular files only.
> 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;
> }
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 00ddf22..7390b25 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -141,7 +141,8 @@ void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
> }
>
> if (flags & BTRFS_INODE_NODATACOW)
> - BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
> + BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW |
> + BTRFS_INODE_NODATASUM;
But now this will happen to:
* nodes (mknod)
* directories -- NODATASUM for a dir does nothing, but does not feel
right
* symlinks -- same
* subvolume roots -- same, and even more confusing what it does
While the fix you suggested in
http://www.mail-archive.com/linux-btrfs@xxxxxxxxxxxxxxx/msg18292.html
is simple, I'm still inclined to keep all flag inheritance at one place,
so the fix I'm proposing is to do
> 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);
> }
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