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

Dave Chinner
2019-08-28T04:23:58Z

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.
*
* 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.
*/
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