Re: [PATCH v7 03/19] xfs: Add xfs_has_attr and subroutines

From: Brian Foster <bfoster@redhat.com>
To: Allison Collins <allison.henderson@oracle.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH v7 03/19] xfs: Add xfs_has_attr and subroutines
Date: Tue, 25 Feb 2020 08:25:21 -0500	[thread overview]
Message-ID: <20200225132521.GA21304@bfoster> (raw)
In-Reply-To: <2871cf8f-5bef-7e0a-33d0-c58a14763be8@oracle.com>

On Mon, Feb 24, 2020 at 02:18:35PM -0700, Allison Collins wrote:
> 
> 
> On 2/24/20 6:08 AM, Brian Foster wrote:
> > On Sat, Feb 22, 2020 at 07:05:55PM -0700, Allison Collins wrote:
> > > From: Allison Henderson <allison.henderson@oracle.com>
> > > 
> > > This patch adds a new functions to check for the existence of an attribute.
> > > Subroutines are also added to handle the cases of leaf blocks, nodes or shortform.
> > > Common code that appears in existing attr add and remove functions have been
> > > factored out to help reduce the appearance of duplicated code.  We will need these
> > > routines later for delayed attributes since delayed operations cannot return error
> > > codes.
> > > 
> > > Signed-off-by: Allison Collins <allison.henderson@oracle.com>
> > > ---
> > >   fs/xfs/libxfs/xfs_attr.c      | 171 ++++++++++++++++++++++++++++--------------
> > >   fs/xfs/libxfs/xfs_attr.h      |   1 +
> > >   fs/xfs/libxfs/xfs_attr_leaf.c | 111 +++++++++++++++++----------
> > >   fs/xfs/libxfs/xfs_attr_leaf.h |   3 +
> > >   4 files changed, 188 insertions(+), 98 deletions(-)
> > > 
> > > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > > index 9acdb23..2255060 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.c
> > > +++ b/fs/xfs/libxfs/xfs_attr.c
> > ...
> > > @@ -310,6 +313,37 @@ xfs_attr_set_args(
> > >   }
> > >   /*
> > > + * Return EEXIST if attr is found, or ENOATTR if not
> > > + */
> > > +int
> > > +xfs_has_attr(
> > > +	struct xfs_da_args      *args)
> > > +{
> > > +	struct xfs_inode	*dp = args->dp;
> > > +	struct xfs_buf		*bp = NULL;
> > > +	int			error;
> > > +
> > > +	if (!xfs_inode_hasattr(dp))
> > > +		return -ENOATTR;
> > > +
> > > +	if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL) {
> > > +		ASSERT(dp->i_afp->if_flags & XFS_IFINLINE);
> > > +		return xfs_attr_sf_findname(args, NULL, NULL);
> > 
> > Nit: any reason we use "findname" here and "hasname" for the other two
> > variants?
> It was asked for in the v4 review.  Reason being we also return the location
> of the sf entry and byte offset.
> 

Ok.

> > 
> > Just a few other nit level things..
> > 
> > > +	}
> > > +
> > > +	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> > > +		error = xfs_attr_leaf_hasname(args, &bp);
> > > +
> > > +		if (bp)
> > > +			xfs_trans_brelse(args->trans, bp);
> > > +
> > > +		return error;
> > > +	}
> > > +
> > > +	return xfs_attr_node_hasname(args, NULL);
> > > +}
> > > +
> > > +/*
> > >    * Remove the attribute specified in @args.
> > >    */
> > >   int
> > ...
> > > @@ -773,12 +822,11 @@ xfs_attr_leaf_removename(
> > >   	 * Remove the attribute.
> > >   	 */
> > >   	dp = args->dp;
> > > -	args->blkno = 0;
> > > -	error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, &bp);
> > > -	if (error)
> > > +
> > > +	error = xfs_attr_leaf_hasname(args, &bp);
> > > +	if (error != -ENOATTR && error != -EEXIST)
> > >   		return error;
> > > -	error = xfs_attr3_leaf_lookup_int(bp, args);
> > >   	if (error == -ENOATTR) {
> > 
> > It looks like some of these error checks could be cleaned up where the
> > helper function is used. I.e., something like the following here:
> > 
> > 	if (error == -ENOATTR) {
> > 		xfs_trans_brelse(...);
> > 		return error;
> > 	} else if (error != -EEXIST)
> > 		return error;
> Sure, I'm starting to get more pressure in other reviews to change this api
> to a boolean return type though (1: y, 0: no, <0: error).  I think we talked
> about this in v3, but decided to stick with this original api for now.  I'm
> thinking maybe adding a patch at the end to shift the api might be a good
> compromise?  Thoughts?
> 

I think Dave commented on this earlier with regard to some of these API
cleanups being orthogonal to this work. The big challenge with this
series is really taking apart this big tangle of xattr code such that it
has smaller components and is thus mostly reusable between dfops context
for parent pointers etc. and the traditional codepath. I can see the
appeal of such API cleanups (so it's good feedback overall), but I agree
that it's probably wiser to allow this series to work with the interface
style we have in the existing code and consider that type of thing as a
follow on cleanup when the subsystem itself is more stabilized.

Brian

> > 
> > >   		xfs_trans_brelse(args->trans, bp);
> > >   		return error;
> > > @@ -817,12 +865,10 @@ xfs_attr_leaf_get(xfs_da_args_t *args)
> > >   	trace_xfs_attr_leaf_get(args);
> > > -	args->blkno = 0;
> > > -	error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, &bp);
> > > -	if (error)
> > > +	error = xfs_attr_leaf_hasname(args, &bp);
> > > +	if (error != -ENOATTR && error != -EEXIST)
> > >   		return error;
> > > -	error = xfs_attr3_leaf_lookup_int(bp, args);
> > >   	if (error != -EEXIST)  {
> > >   		xfs_trans_brelse(args->trans, bp);
> > >   		return error;
> > 
> > Similar thing here, just reordering the checks simplifies the logic.
> Sure, will do.
> 
> > 
> > > @@ -832,6 +878,41 @@ xfs_attr_leaf_get(xfs_da_args_t *args)
> > >   	return error;
> > >   }
> > > +/*
> > > + * Return EEXIST if attr is found, or ENOATTR if not
> > > + * statep: If not null is set to point at the found state.  Caller will
> > > + *         be responsible for freeing the state in this case.
> > > + */
> > > +STATIC int
> > > +xfs_attr_node_hasname(
> > > +	struct xfs_da_args	*args,
> > > +	struct xfs_da_state	**statep)
> > > +{
> > > +	struct xfs_da_state	*state;
> > > +	int			retval, error;
> > > +
> > > +	state = xfs_da_state_alloc();
> > > +	state->args = args;
> > > +	state->mp = args->dp->i_mount;
> > > +
> > > +	if (statep != NULL)
> > > +		*statep = NULL;
> > > +
> > > +	/*
> > > +	 * Search to see if name exists, and get back a pointer to it.
> > > +	 */
> > > +	error = xfs_da3_node_lookup_int(state, &retval);
> > > +	if (error == 0) {
> > > +		if (statep != NULL)
> > > +			*statep = state;
> > > +		return retval;
> > > +	}
> > > +
> > > +	xfs_da_state_free(state);
> > > +
> > > +	return error;
> > > +}
> > > +
> > >   /*========================================================================
> > >    * External routines when attribute list size > geo->blksize
> > >    *========================================================================*/
> > ...
> > > @@ -1316,31 +1381,23 @@ xfs_attr_node_get(xfs_da_args_t *args)
> > >   {
> > >   	xfs_da_state_t *state;
> > >   	xfs_da_state_blk_t *blk;
> > > -	int error, retval;
> > > +	int error;
> > >   	int i;
> > >   	trace_xfs_attr_node_get(args);
> > > -	state = xfs_da_state_alloc();
> > > -	state->args = args;
> > > -	state->mp = args->dp->i_mount;
> > > -
> > >   	/*
> > >   	 * Search to see if name exists, and get back a pointer to it.
> > >   	 */
> > > -	error = xfs_da3_node_lookup_int(state, &retval);
> > > -	if (error) {
> > > -		retval = error;
> > > -		goto out_release;
> > > -	}
> > > -	if (retval != -EEXIST)
> > > +	error = xfs_attr_node_hasname(args, &state);
> > > +	if (error != -EEXIST)
> > >   		goto out_release;
> > >   	/*
> > >   	 * Get the value, local or "remote"
> > >   	 */
> > >   	blk = &state->path.blk[state->path.active - 1];
> > > -	retval = xfs_attr3_leaf_getvalue(blk->bp, args);
> > > +	error = xfs_attr3_leaf_getvalue(blk->bp, args);
> > >   	/*
> > >   	 * If not in a transaction, we have to release all the buffers.
> > > @@ -1352,7 +1409,7 @@ xfs_attr_node_get(xfs_da_args_t *args)
> > >   	}
> > >   	xfs_da_state_free(state);
> > 
> > Do we need an 'if (state)' check here like the other node funcs?
> I think so, because if xfs_attr_node_hasname errors out it releases the
> state.  Will add.
> 
> > 
> > > -	return retval;
> > > +	return error;
> > >   }
> > >   /* Returns true if the attribute entry name is valid. */
> > ...
> > > diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> > > index cb5ef66..9d6b68c 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> > > +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> > > @@ -654,18 +654,66 @@ xfs_attr_shortform_create(xfs_da_args_t *args)
> > >   }
> > >   /*
> > > + * Return -EEXIST if attr is found, or -ENOATTR if not
> > > + * args:  args containing attribute name and namelen
> > > + * sfep:  If not null, pointer will be set to the last attr entry found on
> > > +	  -EEXIST.  On -ENOATTR pointer is left at the last entry in the list
> > > + * basep: If not null, pointer is set to the byte offset of the entry in the
> > > + *	  list on -EEXIST.  On -ENOATTR, pointer is left at the byte offset of
> > > + *	  the last entry in the list
> > > + */
> > > +int
> > > +xfs_attr_sf_findname(
> > > +	struct xfs_da_args	 *args,
> > > +	struct xfs_attr_sf_entry **sfep,
> > > +	unsigned int		 *basep)
> > > +{
> > > +	struct xfs_attr_shortform *sf;
> > > +	struct xfs_attr_sf_entry *sfe;
> > > +	unsigned int		base = sizeof(struct xfs_attr_sf_hdr);
> > > +	int			size = 0;
> > > +	int			end;
> > > +	int			i;
> > > +
> > > +	sf = (struct xfs_attr_shortform *)args->dp->i_afp->if_u1.if_data;
> > > +	sfe = &sf->list[0];
> > > +	end = sf->hdr.count;
> > > +	for (i = 0; i < end; sfe = XFS_ATTR_SF_NEXTENTRY(sfe),
> > > +			base += size, i++) {
> > 
> > Slightly more readable to align indendation with the sfe assignment
> > above.
> Sure, will fix.  Thanks!
> 
> Allison
> 
> > 
> > Brian
> > 
> > > +		size = XFS_ATTR_SF_ENTSIZE(sfe);
> > > +		if (sfe->namelen != args->name.len)
> > > +			continue;
> > > +		if (memcmp(sfe->nameval, args->name.name, args->name.len) != 0)
> > > +			continue;
> > > +		if (!xfs_attr_namesp_match(args->name.type, sfe->flags))
> > > +			continue;
> > > +		break;
> > > +	}
> > > +
> > > +	if (sfep != NULL)
> > > +		*sfep = sfe;
> > > +
> > > +	if (basep != NULL)
> > > +		*basep = base;
> > > +
> > > +	if (i == end)
> > > +		return -ENOATTR;
> > > +	return -EEXIST;
> > > +}
> > > +
> > > +/*
> > >    * Add a name/value pair to the shortform attribute list.
> > >    * Overflow from the inode has already been checked for.
> > >    */
> > >   void
> > > -xfs_attr_shortform_add(xfs_da_args_t *args, int forkoff)
> > > +xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff)
> > >   {
> > > -	xfs_attr_shortform_t *sf;
> > > -	xfs_attr_sf_entry_t *sfe;
> > > -	int i, offset, size;
> > > -	xfs_mount_t *mp;
> > > -	xfs_inode_t *dp;
> > > -	struct xfs_ifork *ifp;
> > > +	struct xfs_attr_shortform	*sf;
> > > +	struct xfs_attr_sf_entry	*sfe;
> > > +	int				offset, size, error;
> > > +	struct xfs_mount		*mp;
> > > +	struct xfs_inode		*dp;
> > > +	struct xfs_ifork		*ifp;
> > >   	trace_xfs_attr_sf_add(args);
> > > @@ -676,18 +724,8 @@ xfs_attr_shortform_add(xfs_da_args_t *args, int forkoff)
> > >   	ifp = dp->i_afp;
> > >   	ASSERT(ifp->if_flags & XFS_IFINLINE);
> > >   	sf = (xfs_attr_shortform_t *)ifp->if_u1.if_data;
> > > -	sfe = &sf->list[0];
> > > -	for (i = 0; i < sf->hdr.count; sfe = XFS_ATTR_SF_NEXTENTRY(sfe), i++) {
> > > -#ifdef DEBUG
> > > -		if (sfe->namelen != args->name.len)
> > > -			continue;
> > > -		if (memcmp(args->name.name, sfe->nameval, args->name.len) != 0)
> > > -			continue;
> > > -		if (!xfs_attr_namesp_match(args->name.type, sfe->flags))
> > > -			continue;
> > > -		ASSERT(0);
> > > -#endif
> > > -	}
> > > +	error = xfs_attr_sf_findname(args, &sfe, NULL);
> > > +	ASSERT(error != -EEXIST);
> > >   	offset = (char *)sfe - (char *)sf;
> > >   	size = XFS_ATTR_SF_ENTSIZE_BYNAME(args->name.len, args->valuelen);
> > > @@ -730,35 +768,26 @@ xfs_attr_fork_remove(
> > >    * Remove an attribute from the shortform attribute list structure.
> > >    */
> > >   int
> > > -xfs_attr_shortform_remove(xfs_da_args_t *args)
> > > +xfs_attr_shortform_remove(struct xfs_da_args *args)
> > >   {
> > > -	xfs_attr_shortform_t *sf;
> > > -	xfs_attr_sf_entry_t *sfe;
> > > -	int base, size=0, end, totsize, i;
> > > -	xfs_mount_t *mp;
> > > -	xfs_inode_t *dp;
> > > +	struct xfs_attr_shortform	*sf;
> > > +	struct xfs_attr_sf_entry	*sfe;
> > > +	int				size = 0, end, totsize;
> > > +	unsigned int			base;
> > > +	struct xfs_mount		*mp;
> > > +	struct xfs_inode		*dp;
> > > +	int				error;
> > >   	trace_xfs_attr_sf_remove(args);
> > >   	dp = args->dp;
> > >   	mp = dp->i_mount;
> > > -	base = sizeof(xfs_attr_sf_hdr_t);
> > >   	sf = (xfs_attr_shortform_t *)dp->i_afp->if_u1.if_data;
> > > -	sfe = &sf->list[0];
> > > -	end = sf->hdr.count;
> > > -	for (i = 0; i < end; sfe = XFS_ATTR_SF_NEXTENTRY(sfe),
> > > -					base += size, i++) {
> > > -		size = XFS_ATTR_SF_ENTSIZE(sfe);
> > > -		if (sfe->namelen != args->name.len)
> > > -			continue;
> > > -		if (memcmp(sfe->nameval, args->name.name, args->name.len) != 0)
> > > -			continue;
> > > -		if (!xfs_attr_namesp_match(args->name.type, sfe->flags))
> > > -			continue;
> > > -		break;
> > > -	}
> > > -	if (i == end)
> > > -		return -ENOATTR;
> > > +
> > > +	error = xfs_attr_sf_findname(args, &sfe, &base);
> > > +	if (error != -EEXIST)
> > > +		return error;
> > > +	size = XFS_ATTR_SF_ENTSIZE(sfe);
> > >   	/*
> > >   	 * Fix up the attribute fork data, covering the hole
> > > diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h
> > > index 73615b1..0e9c87c 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_leaf.h
> > > +++ b/fs/xfs/libxfs/xfs_attr_leaf.h
> > > @@ -53,6 +53,9 @@ int	xfs_attr_shortform_getvalue(struct xfs_da_args *args);
> > >   int	xfs_attr_shortform_to_leaf(struct xfs_da_args *args,
> > >   			struct xfs_buf **leaf_bp);
> > >   int	xfs_attr_shortform_remove(struct xfs_da_args *args);
> > > +int	xfs_attr_sf_findname(struct xfs_da_args *args,
> > > +			     struct xfs_attr_sf_entry **sfep,
> > > +			     unsigned int *basep);
> > >   int	xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
> > >   int	xfs_attr_shortform_bytesfit(struct xfs_inode *dp, int bytes);
> > >   xfs_failaddr_t xfs_attr_shortform_verify(struct xfs_inode *ip);
> > > -- 
> > > 2.7.4
> > > 
> > 
> 