Re: [PATCH 1/3] xfs: make attr lookup returns consistent

Darrick J. Wong
2019-08-28T22:03:41Z

On Wed, Aug 28, 2019 at 02:23:48PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> Shortform, leaf and remote value attr value retrieval return
> different values for success. This makes it more complex to handle
> actual errors xfs_attr_get() as some errors mean success and some
> mean failure. Make the return values consistent for success and
> failure consistent for all attribute formats.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
> fs/xfs/libxfs/xfs_attr.c | 57 +++++++++++++++++++++------------
> fs/xfs/libxfs/xfs_attr_leaf.c | 15 ++++++---
> fs/xfs/libxfs/xfs_attr_remote.c | 2 ++
> fs/xfs/scrub/attr.c | 2 --
> 4 files changed, 49 insertions(+), 27 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index d48fcf11cc35..776343c4f22b 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -97,7 +97,10 @@ xfs_inode_hasattr(
> * Overall external interface routines.
> *========================================================================*/
>
> -/* Retrieve an extended attribute and its value. Must have ilock. */
> +/*
> + * Retrieve an extended attribute and its value. Must have ilock.
> + * Returns 0 on successful retrieval, otherwise an error.
> + */
> int
> xfs_attr_get_ilocked(
> struct xfs_inode *ip,
> @@ -147,7 +150,7 @@ xfs_attr_get(
> xfs_iunlock(ip, lock_mode);
>
> *valuelenp = args.valuelen;
> - return error == -EEXIST ? 0 : error;
> + return error;
> }
>
> /*
> @@ -768,6 +771,8 @@ xfs_attr_leaf_removename(
> *
> * This leaf block cannot have a "remote" value, we only call this routine
> * if bmap_one_block() says there is only one block (ie: no remote blks).
> + *
> + * Returns 0 on successful retrieval, otherwise an error.
> */
> STATIC int
> xfs_attr_leaf_get(xfs_da_args_t *args)
> @@ -789,10 +794,15 @@ xfs_attr_leaf_get(xfs_da_args_t *args)
> }
> error = xfs_attr3_leaf_getvalue(bp, args);
> xfs_trans_brelse(args->trans, bp);
> - if (!error && (args->rmtblkno > 0) && !(args->flags & ATTR_KERNOVAL)) {
> - error = xfs_attr_rmtval_get(args);
> - }
> - return error;
> + if (error)
> + return error;
> +
> + /* check if we have to retrieve a remote attribute to get the value */
> + if (args->flags & ATTR_KERNOVAL)
> + return 0;
> + if (!args->rmtblkno)
> + return 0;
> + return xfs_attr_rmtval_get(args);
> }
>
> /*========================================================================
> @@ -1268,11 +1278,13 @@ xfs_attr_refillstate(xfs_da_state_t *state)
> }
>
> /*
> - * Look up a filename in a node attribute list.
> + * Retreive the attribute data from a node attribute list.

"Retrieve"

> *
> * This routine gets called for any attribute fork that has more than one
> * block, ie: both true Btree attr lists and for single-leaf-blocks with
> * "remote" values taking up more blocks.
> + *
> + * Returns 0 on successful retrieval, otherwise an error.
> */
> STATIC int
> xfs_attr_node_get(xfs_da_args_t *args)
> @@ -1289,29 +1301,32 @@ xfs_attr_node_get(xfs_da_args_t *args)
> state->mp = args->dp->i_mount;
>
> /*
> - * Search to see if name exists, and get back a pointer to it.
> + Search to see if name exists, and get back a pointer to it.

Comment damage here?

Meh whatever will just fix it.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> */
> error = xfs_da3_node_lookup_int(state, &retval);
> if (error) {
> retval = error;
> - } else if (retval == -EEXIST) {
> - blk = &state->path.blk[ state->path.active-1 ];
> - ASSERT(blk->bp != NULL);
> - ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
> -
> - /*
> - * Get the value, local or "remote"
> - */
> - retval = xfs_attr3_leaf_getvalue(blk->bp, args);
> - if (!retval && (args->rmtblkno > 0)
> - && !(args->flags & ATTR_KERNOVAL)) {
> - retval = xfs_attr_rmtval_get(args);
> - }
> + goto out_release;
> }
> + if (retval != -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);
> + if (retval)
> + goto out_release;
> + if (args->flags & ATTR_KERNOVAL)
> + goto out_release;
> + if (args->rmtblkno > 0)
> + retval = xfs_attr_rmtval_get(args);
>
> /*
> * If not in a transaction, we have to release all the buffers.
> */
> +out_release:
> for (i = 0; i < state->path.active; i++) {
> xfs_trans_brelse(args->trans, state->path.blk[i].bp);
> state->path.blk[i].bp = NULL;
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> index 70eb941d02e4..d056767b5c53 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> @@ -720,9 +720,12 @@ xfs_attr_shortform_lookup(xfs_da_args_t *args)
> }
>
> /*
> - * Look up a name in a shortform attribute list structure.
> + * Retreive the attribute value and length.
> + *
> + * If ATTR_KERNOVAL is specified, only the length needs to be returned.
> + * Unlike a lookup, we only return an error if the attribute does not
> + * exist or we can't retrieve the value.
> */
> -/*ARGSUSED*/
> int
> xfs_attr_shortform_getvalue(xfs_da_args_t *args)
> {
> @@ -743,7 +746,7 @@ xfs_attr_shortform_getvalue(xfs_da_args_t *args)
> continue;
> if (args->flags & ATTR_KERNOVAL) {
> args->valuelen = sfe->valuelen;
> - return -EEXIST;
> + return 0;
> }
> if (args->valuelen < sfe->valuelen) {
> args->valuelen = sfe->valuelen;
> @@ -752,7 +755,7 @@ xfs_attr_shortform_getvalue(xfs_da_args_t *args)
> args->valuelen = sfe->valuelen;
> memcpy(args->value, &sfe->nameval[args->namelen],
> args->valuelen);
> - return -EEXIST;
> + return 0;
> }
> return -ENOATTR;
> }
> @@ -2350,6 +2353,10 @@ xfs_attr3_leaf_lookup_int(
> /*
> * Get the value associated with an attribute name from a leaf attribute
> * list structure.
> + *
> + * If ATTR_KERNOVAL is specified, only the length needs to be returned.
> + * Unlike a lookup, we only return an error if the attribute does not
> + * exist or we can't retrieve the value.
> */
> int
> xfs_attr3_leaf_getvalue(
> diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
> index 4eb30d357045..3e39b7d40f25 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.c
> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> @@ -358,6 +358,8 @@ xfs_attr_rmtval_copyin(
> /*
> * Read the value associated with an attribute from the out-of-line buffer
> * that we stored it in.
> + *
> + * Returns 0 on successful retrieval, otherwise an error.
> */
> int
> xfs_attr_rmtval_get(
> diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
> index 1afc58bf71dd..e9248ad4f842 100644
> --- a/fs/xfs/scrub/attr.c
> +++ b/fs/xfs/scrub/attr.c
> @@ -163,8 +163,6 @@ xchk_xattr_listent(
> args.valuelen = valuelen;
>
> error = xfs_attr_get_ilocked(context->dp, &args);
> - if (error == -EEXIST)
> - error = 0;
> if (!xchk_fblock_process_error(sx->sc, XFS_ATTR_FORK, args.blkno,
> &error))
> goto fail_xref;
> --
> 2.23.0.rc1
>