[03/17] xfs: allow xattr matching on value for local/sf attrs

Commit Message

Darrick J. Wong March 16, 2023, 7:22 p.m. UTC

From: Darrick J. Wong <[e-mail]>

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

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 fs/xfs/libxfs/xfs_attr_leaf.c |   41 +++++++++++++++++++++++++++++++++++------
 fs/xfs/libxfs/xfs_da_btree.h  |    4 +++-
 2 files changed, 38 insertions(+), 7 deletions(-)

Patch

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index e6c4c8b52a55..d05f2c5cc0cc 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -473,10 +473,12 @@  xfs_attr3_leaf_read(
  */
 static bool
 xfs_attr_match(
-	struct xfs_da_args	*args,
-	uint8_t			namelen,
-	unsigned char		*name,
-	int			flags)
+	const struct xfs_da_args	*args,
+	uint8_t				namelen,
+	const unsigned char		*name,
+	unsigned int			valuelen,
+	const void			*value,
+	int				flags)
 {
 
 	if (args->namelen != namelen)
@@ -484,6 +486,23 @@  xfs_attr_match(
 	if (memcmp(args->name, name, namelen) != 0)
 		return false;
 
+	if (args->op_flags & XFS_DA_OP_VLOOKUP) {
+		if (args->valuelen != valuelen)
+			return false;
+		if (args->valuelen && !value) {
+			/* not implemented for remote values */
+			ASSERT(0);
+			return false;
+		}
+		if (valuelen && !args->value) {
+			/* caller gave us valuelen > 0 but no value?? */
+			ASSERT(0);
+			return false;
+		}
+		if (valuelen > 0 && memcmp(args->value, value, valuelen) != 0)
+			return false;
+	}
+
 	/* Recovery ignores the INCOMPLETE flag. */
 	if ((args->op_flags & XFS_DA_OP_RECOVERY) &&
 	    args->attr_filter == (flags & XFS_ATTR_NSP_ONDISK_MASK))
@@ -502,6 +521,10 @@  xfs_attr_copy_value(
 	unsigned char		*value,
 	int			valuelen)
 {
+	/* vlookups already supplied the attr value; don't copy anything */
+	if (args->op_flags & XFS_DA_OP_VLOOKUP)
+		return 0;
+
 	/*
 	 * No copy if all we have to do is get the length
 	 */
@@ -726,6 +749,7 @@  xfs_attr_sf_findname(
 			     base += size, i++) {
 		size = xfs_attr_sf_entsize(sfe);
 		if (!xfs_attr_match(args, sfe->namelen, sfe->nameval,
+				    sfe->valuelen, &sfe->nameval[sfe->namelen],
 				    sfe->flags))
 			continue;
 		break;
@@ -896,6 +920,7 @@  xfs_attr_shortform_lookup(xfs_da_args_t *args)
 	for (i = 0; i < sf->hdr.count;
 				sfe = xfs_attr_sf_nextentry(sfe), i++) {
 		if (xfs_attr_match(args, sfe->namelen, sfe->nameval,
+				sfe->valuelen, &sfe->nameval[sfe->namelen],
 				sfe->flags))
 			return -EEXIST;
 	}
@@ -923,6 +948,7 @@  xfs_attr_shortform_getvalue(
 	for (i = 0; i < sf->hdr.count;
 				sfe = xfs_attr_sf_nextentry(sfe), i++) {
 		if (xfs_attr_match(args, sfe->namelen, sfe->nameval,
+				sfe->valuelen, &sfe->nameval[sfe->namelen],
 				sfe->flags))
 			return xfs_attr_copy_value(args,
 				&sfe->nameval[args->namelen], sfe->valuelen);
@@ -2484,14 +2510,17 @@  xfs_attr3_leaf_lookup_int(
 		if (entry->flags & XFS_ATTR_LOCAL) {
 			name_loc = xfs_attr3_leaf_name_local(leaf, probe);
 			if (!xfs_attr_match(args, name_loc->namelen,
-					name_loc->nameval, entry->flags))
+					name_loc->nameval,
+					be16_to_cpu(name_loc->valuelen),
+					&name_loc->nameval[name_loc->namelen],
+					entry->flags))
 				continue;
 			args->index = probe;
 			return -EEXIST;
 		} else {
 			name_rmt = xfs_attr3_leaf_name_remote(leaf, probe);
 			if (!xfs_attr_match(args, name_rmt->namelen,
-					name_rmt->name, entry->flags))
+					name_rmt->name, 0, NULL, entry->flags))
 				continue;
 			args->index = probe;
 			args->rmtvaluelen = be32_to_cpu(name_rmt->valuelen);
diff --git a/fs/xfs/libxfs/xfs_da_btree.h b/fs/xfs/libxfs/xfs_da_btree.h
index 90b86d00258f..6132787ad1f4 100644
--- a/fs/xfs/libxfs/xfs_da_btree.h
+++ b/fs/xfs/libxfs/xfs_da_btree.h
@@ -96,6 +96,7 @@  typedef struct xfs_da_args {
 #define XFS_DA_OP_REMOVE	(1u << 6) /* this is a remove operation */
 #define XFS_DA_OP_RECOVERY	(1u << 7) /* Log recovery operation */
 #define XFS_DA_OP_LOGGED	(1u << 8) /* Use intent items to track op */
+#define XFS_DA_OP_VLOOKUP	(1u << 9) /* Compare local attr value for lookup */
 
 #define XFS_DA_OP_FLAGS \
 	{ XFS_DA_OP_JUSTCHECK,	"JUSTCHECK" }, \
@@ -106,7 +107,8 @@  typedef struct xfs_da_args {
 	{ XFS_DA_OP_NOTIME,	"NOTIME" }, \
 	{ XFS_DA_OP_REMOVE,	"REMOVE" }, \
 	{ XFS_DA_OP_RECOVERY,	"RECOVERY" }, \
-	{ XFS_DA_OP_LOGGED,	"LOGGED" }
+	{ XFS_DA_OP_LOGGED,	"LOGGED" }, \
+	{ XFS_DA_OP_VLOOKUP,	"VLOOKUP" }
 
 /*
  * Storage for holding state during Btree searches and split/join ops.