Re: [PATCH] Btrfs: only inherit btrfs specific flags when creating files

[Liu Bo <liubo2009@cn.fujitsu.com>]

On 09/27/2011 11:02 PM, Josef Bacik wrote:
> Xfstests 79 was failing because we were inheriting the S_APPEND flag when we
> weren't supposed to.  There isn't any specific documentation on this so I'm
> taking the test as the standard of how things work, and having S_APPEND set on a
> directory doesn't mean that S_APPEND gets inherited by its children according to
> this test.  So only inherit btrfs specific things.  This will let us set
> compress/nocompress on specific directories and everything in the directories
> will inherit this flag, same with nodatacow.  With this patch test 79 passes.
> Thanks,
> 

I've checked ext3&4, they have such comments:

/* Flags that should be inherited by new inodes from their parent. */
#define EXT3_FL_INHERITED (EXT3_SECRM_FL | EXT3_UNRM_FL | EXT3_COMPR_FL |\
                           EXT3_SYNC_FL | EXT3_IMMUTABLE_FL | EXT3_APPEND_FL |\
                           EXT3_NODUMP_FL | EXT3_NOATIME_FL | EXT3_COMPRBLK_FL|\
                           EXT3_NOCOMPR_FL | EXT3_JOURNAL_DATA_FL |\
                           EXT3_NOTAIL_FL | EXT3_DIRSYNC_FL)

It shows EXT[3,4]_APPEND_FL should be inherited from their parent, is this the standard?


thanks,
liubo

> Signed-off-by: Josef Bacik <josef@redhat.com>
> ---
>  fs/btrfs/ioctl.c |   17 +++++++++++------
>  1 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 24fd75b..d2b53eb 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -117,7 +117,7 @@ void btrfs_update_iflags(struct inode *inode)
>  /*
>   * Inherit flags from the parent inode.
>   *
> - * Unlike extN we don't have any flags we don't want to inherit currently.
> + * Currently only the compression flags and the cow flags are inherited.
>   */
>  void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
>  {
> @@ -128,12 +128,17 @@ void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
>  
>  	flags = BTRFS_I(dir)->flags;
>  
> -	if (S_ISREG(inode->i_mode))
> -		flags &= ~BTRFS_INODE_DIRSYNC;
> -	else if (!S_ISDIR(inode->i_mode))
> -		flags &= (BTRFS_INODE_NODUMP | BTRFS_INODE_NOATIME);
> +	if (flags & BTRFS_INODE_NOCOMPRESS) {
> +		BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
> +		BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
> +	} else if (flags & BTRFS_INODE_COMPRESS) {
> +		BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
> +		BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
> +	}
> +
> +	if (flags & BTRFS_INODE_NODATACOW)
> +		BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
>  
> -	BTRFS_I(inode)->flags = flags;
>  	btrfs_update_iflags(inode);
>  }
>