Re: [PATCH 19/21] xfs: Add the parent pointer support to the superblock version 5.

[Allison Henderson <allison.henderson@oracle.com>]

On 05/07/2018 02:38 PM, Darrick J. Wong wrote:
> On Sun, May 06, 2018 at 10:24:52AM -0700, Allison Henderson wrote:
>> [dchinner: forward ported and cleaned up]
>> [achender: rebased and added parent pointer attribute to
>>             compatible attributes mask]
>>
>> Signed-off-by: Mark Tinguely <tinguely@sgi.com>
>> Signed-off-by: Dave Chinner <dchinner@redhat.com>
>> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> 
> Old kernels can't accidentally start returning the ATTR_PARENT
> attributes, right?  I think the answer is yes.....?
> 
> If so,
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> --D

I suppose it's possible, though it wouldn't seem correct if they didn't
actually support the feature.  Maybe I'm not understanding your concern? 
  You are concerned as to how we handle old file systems that may have 
incorrectly set the attribute?

Allison
> 
>> ---
>>   fs/xfs/libxfs/xfs_format.h | 7 +++++--
>>   fs/xfs/libxfs/xfs_fs.h     | 1 +
>>   fs/xfs/libxfs/xfs_sb.c     | 2 ++
>>   fs/xfs/xfs_super.c         | 4 ++++
>>   4 files changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
>> index 5e946c8..d05ffc5 100644
>> --- a/fs/xfs/libxfs/xfs_format.h
>> +++ b/fs/xfs/libxfs/xfs_format.h
>> @@ -462,10 +462,12 @@ xfs_sb_has_compat_feature(
>>   #define XFS_SB_FEAT_RO_COMPAT_FINOBT   (1 << 0)		/* free inode btree */
>>   #define XFS_SB_FEAT_RO_COMPAT_RMAPBT   (1 << 1)		/* reverse map btree */
>>   #define XFS_SB_FEAT_RO_COMPAT_REFLINK  (1 << 2)		/* reflinked files */
>> +#define XFS_SB_FEAT_RO_COMPAT_PARENT	(1 << 3)		/* parent inode ptr */
>>   #define XFS_SB_FEAT_RO_COMPAT_ALL \
>>   		(XFS_SB_FEAT_RO_COMPAT_FINOBT | \
>>   		 XFS_SB_FEAT_RO_COMPAT_RMAPBT | \
>> -		 XFS_SB_FEAT_RO_COMPAT_REFLINK)
>> +		 XFS_SB_FEAT_RO_COMPAT_REFLINK| \
>> +		 XFS_SB_FEAT_RO_COMPAT_PARENT)
>>   #define XFS_SB_FEAT_RO_COMPAT_UNKNOWN	~XFS_SB_FEAT_RO_COMPAT_ALL
>>   static inline bool
>>   xfs_sb_has_ro_compat_feature(
>> @@ -561,7 +563,8 @@ static inline bool xfs_sb_version_hasreflink(struct xfs_sb *sbp)
>>   
>>   static inline bool xfs_sb_version_hasparent(struct xfs_sb *sbp)
>>   {
>> -	return false; /* We'll enable this at the end of the set */
>> +	return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
>> +		(sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_PARENT));
>>   }
>>   
>>   /*
>> diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
>> index faf1a4e..641e0af 100644
>> --- a/fs/xfs/libxfs/xfs_fs.h
>> +++ b/fs/xfs/libxfs/xfs_fs.h
>> @@ -222,6 +222,7 @@ typedef struct xfs_fsop_resblks {
>>   #define XFS_FSOP_GEOM_FLAGS_SPINODES	0x40000	/* sparse inode chunks	*/
>>   #define XFS_FSOP_GEOM_FLAGS_RMAPBT	0x80000	/* reverse mapping btree */
>>   #define XFS_FSOP_GEOM_FLAGS_REFLINK	0x100000 /* files can share blocks */
>> +#define XFS_FSOP_GEOM_FLAGS_PARENT	0x200000 /* parent pointers */
>>   
>>   /*
>>    * Minimum and maximum sizes need for growth checks.
>> diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
>> index d9b94bd..e1f0ac1 100644
>> --- a/fs/xfs/libxfs/xfs_sb.c
>> +++ b/fs/xfs/libxfs/xfs_sb.c
>> @@ -955,6 +955,8 @@ xfs_fs_geometry(
>>   		geo->flags |= XFS_FSOP_GEOM_FLAGS_RMAPBT;
>>   	if (xfs_sb_version_hasreflink(sbp))
>>   		geo->flags |= XFS_FSOP_GEOM_FLAGS_REFLINK;
>> +	if(xfs_sb_version_hasparent(sbp))
>> +		geo->flags |= XFS_FSOP_GEOM_FLAGS_PARENT;
>>   	if (xfs_sb_version_hassector(sbp))
>>   		geo->logsectsize = sbp->sb_logsectsize;
>>   	else
>> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
>> index dce3baf..366deee 100644
>> --- a/fs/xfs/xfs_super.c
>> +++ b/fs/xfs/xfs_super.c
>> @@ -1731,6 +1731,10 @@ xfs_fs_fill_super(
>>   		goto out_filestream_unmount;
>>   	}
>>   
>> +	if (xfs_sb_version_hasparent(&mp->m_sb))
>> +		xfs_alert(mp,
>> +	"EXPERIMENTAL parent pointer feature enabled. Use at your own risk!");
>> +
>>   	error = xfs_mountfs(mp);
>>   	if (error)
>>   		goto out_filestream_unmount;
>> -- 
>> 2.7.4
>>
>> --
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