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

Allison Collins
2020-02-23T17:28:58Z

On 2/23/20 5:20 AM, Amir Goldstein wrote:
> On Sun, Feb 23, 2020 at 4:07 AM Allison Collins
> <allison.henderson@oracle.com> 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
>> @@ -46,6 +46,7 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);
>> STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
>> STATIC int xfs_attr_leaf_addname(xfs_da_args_t *args);
>> STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
>> +STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
>>
>> /*
>> * Internal routines when attribute list is more than one block.
>> @@ -53,6 +54,8 @@ STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
>> STATIC int xfs_attr_node_get(xfs_da_args_t *args);
>> STATIC int xfs_attr_node_addname(xfs_da_args_t *args);
>> STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
>> +STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
>> + struct xfs_da_state **state);
>> STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
>> STATIC int xfs_attr_refillstate(xfs_da_state_t *state);
>>
>> @@ -310,6 +313,37 @@ xfs_attr_set_args(
>> }
>>
>> /*
>> + * Return EEXIST if attr is found, or ENOATTR if not
>
> This is a very silly return value for a function named has_attr in my taste.
> I realize you inherited this interface from xfs_attr3_leaf_lookup_int(), but
> IMO this change looks like a very good opportunity to change that internal
> API:
>
> xfs_has_attr?
>
> 0: NO
> 1: YES (or stay with the syscall standard of -ENOATTR)
> <0: error
Darrick had mentioned something like that in the last revision, but I
think people wanted to keep everything a straight hoist at this phase.
At least as much as possible. Maybe I can add another patch that does
this at the end when we're doing clean ups.

Allison

>
>> + */
>> +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);
>> + }
>> +
>> + 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
>> @@ -583,26 +617,20 @@ STATIC int
>> xfs_attr_leaf_addname(
>> struct xfs_da_args *args)
>> {
>> - struct xfs_inode *dp;
>> struct xfs_buf *bp;
>> int retval, error, forkoff;
>> + struct xfs_inode *dp = args->dp;
>>
>> trace_xfs_attr_leaf_addname(args);
>>
>> /*
>> - * Read the (only) block in the attribute list in.
>> - */
>> - dp = args->dp;
>> - args->blkno = 0;
>> - error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, &bp);
>> - if (error)
>> - return error;
>> -
>> - /*
>> * Look up the given attribute in the leaf block. Figure out if
>> * the given flags produce an error or call for an atomic rename.
>> */
>> - retval = xfs_attr3_leaf_lookup_int(bp, args);
>> + retval = xfs_attr_leaf_hasname(args, &bp);
>> + if (retval != -ENOATTR && retval != -EEXIST)
>> + return retval;
>> +
>> if ((args->name.type & ATTR_REPLACE) && (retval == -ENOATTR)) {
>
> Example of how sane code (in my taste) would look like:
>
> retval = xfs_attr_leaf_hasname(args, &bp);
> if (retval < 0)
> return retval;
>
> if ((args->name.type & ATTR_REPLACE) && !retval) {
> xfs_trans_brelse(args->trans, bp);
> return -ENOATTR;
> } else if (retval) {
> if (args->flags & ATTR_CREATE) { /* pure create op */
> xfs_trans_brelse(args->trans, bp);
> return -EEXIST;
> }
>
> Thanks,
> Amir.
>