xfs: remove ATTR_ALLOC and XFS_DA_OP_ALLOCVAL

Use a NULL args->value as the indicator to lazily allocate a buffer
instead, and let the caller always free args->value instead of
duplicating the cleanup.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Chandan Rajendra <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_attr.c

@@ -98,15 +98,14 @@ xfs_attr_get_ilocked(
  * indication whether the attribute exists and the size of the value if it
  * exists. The size is returned in args.valuelen.
  *
+ * If args->value is NULL but args->valuelen is non-zero, allocate the buffer
+ * for the value after existence of the attribute has been determined. The
+ * caller always has to free args->value if it is set, no matter if this
+ * function was successful or not.
+ *
  * If the attribute is found, but exceeds the size limit set by the caller in
  * args->valuelen, return -ERANGE with the size of the attribute that was found
  * in args->valuelen.
- *
- * If ATTR_ALLOC is set in args->flags, allocate the buffer for the value after
- * existence of the attribute has been determined. On success, return that
- * buffer to the caller and leave them to free it. On failure, free any
- * allocated buffer and ensure the buffer pointer returned to the caller is
- * null.
  */
 int
 xfs_attr_get(
@@ -115,8 +114,6 @@ xfs_attr_get(
 	uint			lock_mode;
 	int			error;
 
-	ASSERT((args->flags & ATTR_ALLOC) || !args->valuelen || args->value);
-
 	XFS_STATS_INC(args->dp->i_mount, xs_attr_get);
 
 	if (XFS_FORCED_SHUTDOWN(args->dp->i_mount))
@@ -128,18 +125,11 @@ xfs_attr_get(
 
 	/* Entirely possible to look up a name which doesn't exist */
 	args->op_flags = XFS_DA_OP_OKNOENT;
-	if (args->flags & ATTR_ALLOC)
-		args->op_flags |= XFS_DA_OP_ALLOCVAL;
 
 	lock_mode = xfs_ilock_attr_map_shared(args->dp);
 	error = xfs_attr_get_ilocked(args);
 	xfs_iunlock(args->dp, lock_mode);
 
-	/* on error, we have to clean up allocated value buffers */
-	if (error && (args->flags & ATTR_ALLOC)) {
-		kmem_free(args->value);
-		args->value = NULL;
-	}
 	return error;
 }
 

fs/xfs/libxfs/xfs_attr.h

@@ -35,10 +35,8 @@ struct xfs_attr_list_context;
 
 #define ATTR_KERNOTIME	0x1000	/* [kernel] don't update inode timestamps */
 
-#define ATTR_ALLOC	0x8000	/* [kernel] allocate xattr buffer on demand */
-
 #define ATTR_KERNEL_FLAGS \
-	(ATTR_KERNOTIME | ATTR_ALLOC)
+	(ATTR_KERNOTIME)
 
 #define XFS_ATTR_FLAGS \
 	{ ATTR_DONTFOLLOW, 	"DONTFOLLOW" }, \
@@ -47,8 +45,7 @@ struct xfs_attr_list_context;
 	{ ATTR_SECURE,		"SECURE" }, \
 	{ ATTR_CREATE,		"CREATE" }, \
 	{ ATTR_REPLACE,		"REPLACE" }, \
-	{ ATTR_KERNOTIME,	"KERNOTIME" }, \
-	{ ATTR_ALLOC,		"ALLOC" }
+	{ ATTR_KERNOTIME,	"KERNOTIME" }
 
 /*
  * The maximum size (into the kernel or returned from the kernel) of an

fs/xfs/libxfs/xfs_attr_leaf.c

@@ -477,7 +477,7 @@ xfs_attr_copy_value(
 		return -ERANGE;
 	}
 
-	if (args->op_flags & XFS_DA_OP_ALLOCVAL) {
+	if (!args->value) {
 		args->value = kmem_alloc_large(valuelen, 0);
 		if (!args->value)
 			return -ENOMEM;

fs/xfs/libxfs/xfs_da_btree.h

@@ -88,7 +88,6 @@ typedef struct xfs_da_args {
 #define XFS_DA_OP_ADDNAME	0x0004	/* this is an add operation */
 #define XFS_DA_OP_OKNOENT	0x0008	/* lookup/add op, ENOENT ok, else die */
 #define XFS_DA_OP_CILOOKUP	0x0010	/* lookup to return CI name if found */
-#define XFS_DA_OP_ALLOCVAL	0x0020	/* lookup to alloc buffer if found  */
 #define XFS_DA_OP_INCOMPLETE	0x0040	/* lookup INCOMPLETE attr keys */
 
 #define XFS_DA_OP_FLAGS \
@@ -97,7 +96,6 @@ typedef struct xfs_da_args {
 	{ XFS_DA_OP_ADDNAME,	"ADDNAME" }, \
 	{ XFS_DA_OP_OKNOENT,	"OKNOENT" }, \
 	{ XFS_DA_OP_CILOOKUP,	"CILOOKUP" }, \
-	{ XFS_DA_OP_ALLOCVAL,	"ALLOCVAL" }, \
 	{ XFS_DA_OP_INCOMPLETE,	"INCOMPLETE" }
 
 /*