Re: [PATCH v22 14/16] xfs: Add delattr mount option

From: "Darrick J. Wong" <djwong@kernel.org>
To: Allison Henderson <allison.henderson@oracle.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH v22 14/16] xfs: Add delattr mount option
Date: Tue, 27 Jul 2021 17:47:57 -0700	[thread overview]
Message-ID: <20210728004757.GB559212@magnolia> (raw)
In-Reply-To: <20210727062053.11129-15-allison.henderson@oracle.com>

On Mon, Jul 26, 2021 at 11:20:51PM -0700, Allison Henderson wrote:
> This patch adds a mount option to enable delayed attributes. Eventually
> this can be removed when delayed attrs becomes permanent.
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_attr.h |  2 +-
>  fs/xfs/xfs_mount.h       |  1 +
>  fs/xfs/xfs_super.c       | 11 ++++++++++-
>  fs/xfs/xfs_xattr.c       |  2 ++
>  4 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index c0c92bd3..d4e7521 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -30,7 +30,7 @@ struct xfs_attr_list_context;
>  
>  static inline bool xfs_hasdelattr(struct xfs_mount *mp)
>  {
> -	return false;
> +	return mp->m_flags & XFS_MOUNT_DELATTR;
>  }
>  
>  /*
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 66a47f5..2945868 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -257,6 +257,7 @@ typedef struct xfs_mount {
>  #define XFS_MOUNT_NOATTR2	(1ULL << 25)	/* disable use of attr2 format */
>  #define XFS_MOUNT_DAX_ALWAYS	(1ULL << 26)
>  #define XFS_MOUNT_DAX_NEVER	(1ULL << 27)
> +#define XFS_MOUNT_DELATTR	(1ULL << 28)	/* enable delayed attributes */

So uh while we're renaming things away from "delattr", maybe this ...

	LOGGED ATTRIBUTE RE PLAY

... really should become the "larp" debug-only mount option.

	XFS_MOUNT_LARP

Yeah.  Do it!!!

>  /*
>   * Max and min values for mount-option defined I/O
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 2c9e26a..39d6645 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -94,7 +94,7 @@ enum {
>  	Opt_filestreams, Opt_quota, Opt_noquota, Opt_usrquota, Opt_grpquota,
>  	Opt_prjquota, Opt_uquota, Opt_gquota, Opt_pquota,
>  	Opt_uqnoenforce, Opt_gqnoenforce, Opt_pqnoenforce, Opt_qnoenforce,
> -	Opt_discard, Opt_nodiscard, Opt_dax, Opt_dax_enum,
> +	Opt_discard, Opt_nodiscard, Opt_dax, Opt_dax_enum, Opt_delattr
>  };
>  
>  static const struct fs_parameter_spec xfs_fs_parameters[] = {
> @@ -139,6 +139,7 @@ static const struct fs_parameter_spec xfs_fs_parameters[] = {
>  	fsparam_flag("nodiscard",	Opt_nodiscard),
>  	fsparam_flag("dax",		Opt_dax),
>  	fsparam_enum("dax",		Opt_dax_enum, dax_param_enums),
> +	fsparam_flag("delattr",		Opt_delattr),

I think you need this line to be guarded by #ifdefs so that the mount
options parsing code will reject -o larp on non-debug kernels.

--D

>  	{}
>  };
>  
> @@ -1273,6 +1274,14 @@ xfs_fs_parse_param(
>  		xfs_mount_set_dax_mode(parsing_mp, result.uint_32);
>  		return 0;
>  #endif
> +#ifdef CONFIG_XFS_DEBUG
> +	case Opt_delattr:
> +		xfs_warn(parsing_mp,
> +			"EXPERIMENTAL logged xattrs feature in use. "
> +			"Use at your own risk");
> +		parsing_mp->m_flags |= XFS_MOUNT_DELATTR;
> +		return 0;
> +#endif
>  	/* Following mount options will be removed in September 2025 */
>  	case Opt_ikeep:
>  		xfs_fs_warn_deprecated(fc, param, XFS_MOUNT_IKEEP, true);
> diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
> index 0d050f8..a4f97e7 100644
> --- a/fs/xfs/xfs_xattr.c
> +++ b/fs/xfs/xfs_xattr.c
> @@ -8,6 +8,8 @@
>  #include "xfs_shared.h"
>  #include "xfs_format.h"
>  #include "xfs_log_format.h"
> +#include "xfs_trans_resv.h"
> +#include "xfs_mount.h"
>  #include "xfs_da_format.h"
>  #include "xfs_trans_resv.h"
>  #include "xfs_mount.h"
> -- 
> 2.7.4
> 