[PATCH 07/32] xfs: allow xattr matching on name and value for local/sf attrs

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Add a new XFS_DA_OP_PARENT flag to signal that the caller wants to look
up a parent pointer extended attribute by name and value.  This only
works with shortform and local attributes.  Only parent pointers need
this functionality and parent pointers cannot be remote xattrs, so this
limitation is ok for now.

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_attr_leaf.c |   44 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 490608bbed7ad..7d74ade47d8f1 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -513,12 +513,33 @@ static inline unsigned int xfs_attr_match_mask(const struct xfs_da_args *args)
 	return XFS_ATTR_NSP_ONDISK_MASK | XFS_ATTR_INCOMPLETE;
 }
 
+static inline bool
+xfs_attr_parent_match(
+	const struct xfs_da_args	*args,
+	const void			*value,
+	unsigned int			valuelen)
+{
+	ASSERT(args->value != NULL);
+
+	/* Parent pointers do not use remote values */
+	if (!value)
+		return false;
+
+	/* The only value we support is a parent rec. */
+	if (valuelen != sizeof(struct xfs_parent_rec))
+		return false;
+
+	return memcmp(args->value, value, valuelen) == 0;
+}
+
 static bool
 xfs_attr_match(
 	struct xfs_da_args	*args,
 	unsigned int		attr_flags,
 	const unsigned char	*name,
-	unsigned int		namelen)
+	unsigned int		namelen,
+	const void		*value,
+	unsigned int		valuelen)
 {
 	unsigned int		mask = xfs_attr_match_mask(args);
 
@@ -529,6 +550,9 @@ xfs_attr_match(
 	if (memcmp(args->name, name, namelen) != 0)
 		return false;
 
+	if (attr_flags & XFS_ATTR_PARENT)
+		return xfs_attr_parent_match(args, value, valuelen);
+
 	return true;
 }
 
@@ -538,6 +562,13 @@ xfs_attr_copy_value(
 	unsigned char		*value,
 	int			valuelen)
 {
+	/*
+	 * Parent pointer lookups require the caller to specify the name and
+	 * value, so don't copy anything.
+	 */
+	if (args->attr_filter & XFS_ATTR_PARENT)
+		return 0;
+
 	/*
 	 * No copy if all we have to do is get the length
 	 */
@@ -747,7 +778,9 @@ xfs_attr_sf_findname(
 	     sfe < xfs_attr_sf_endptr(sf);
 	     sfe = xfs_attr_sf_nextentry(sfe)) {
 		if (xfs_attr_match(args, sfe->flags, sfe->nameval,
-					sfe->namelen))
+					sfe->namelen,
+					&sfe->nameval[sfe->namelen],
+					sfe->valuelen))
 			return sfe;
 	}
 
@@ -2444,14 +2477,17 @@ xfs_attr3_leaf_lookup_int(
 			name_loc = xfs_attr3_leaf_name_local(leaf, probe);
 			if (!xfs_attr_match(args, entry->flags,
 						name_loc->nameval,
-						name_loc->namelen))
+						name_loc->namelen,
+						&name_loc->nameval[name_loc->namelen],
+						be16_to_cpu(name_loc->valuelen)))
 				continue;
 			args->index = probe;
 			return -EEXIST;
 		} else {
 			name_rmt = xfs_attr3_leaf_name_remote(leaf, probe);
 			if (!xfs_attr_match(args, entry->flags, name_rmt->name,
-						name_rmt->namelen))
+						name_rmt->namelen, NULL,
+						be32_to_cpu(name_rmt->valuelen)))
 				continue;
 			args->index = probe;
 			args->rmtvaluelen = be32_to_cpu(name_rmt->valuelen);