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

Allison Collins
2020-02-24T21:20:43Z

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.

>
> 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?

>
>> 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
>>
>