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

Allison Henderson
2021-07-28T09:05:16Z

On 7/27/21 7:13 PM, Dave Chinner wrote:
> On Tue, Jul 27, 2021 at 05:47:57PM -0700, Darrick J. Wong wrote:
>> 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.
>
> As i mentioned on #xfs, this really should be like the "always_cow"
> debug option - access it via /sys/fs/xfs/debug/larping_with_larts -
> rather than being a mount option that users might accidentally
> discover and start using...
>
> Cheers,
>
> Dave.
Sure, if folks are ok with that, I'll take a look at always_cow, and see
if I can put together something similar for larp. Or larping_with_larts
if folks prefer :-) Thanks for the review!

Allison
>