xfs: move the legacy xfs_attr_list to xfs_ioctl.c

The old xfs_attr_list code is only used by the attrlist by handle
ioctl.  Move it to xfs_ioctl.c with its user.  Also move the
attrlist and attrlist_ent structure to xfs_fs.h, as they are exposed
user ABIs.  They are used through libattr headers with the same name
by at least xfsdump.  Also document this relation so that it doesn't
require a research project to figure out.

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>

1 files changed, 20 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index ef95ca07d084..ae77bcd8c05b 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -572,6 +572,26 @@ typedef struct xfs_attrlist_cursor {
 	__u32		opaque[4];
 } xfs_attrlist_cursor_t;
 
+/*
+ * Define how lists of attribute names are returned to userspace from the
+ * XFS_IOC_ATTRLIST_BY_HANDLE ioctl.  struct xfs_attrlist is the header at the
+ * beginning of the returned buffer, and a each entry in al_offset contains the
+ * relative offset of an xfs_attrlist_ent containing the actual entry.
+ *
+ * NOTE: struct xfs_attrlist must match struct attrlist defined in libattr, and
+ * struct xfs_attrlist_ent must match struct attrlist_ent defined in libattr.
+ */
+struct xfs_attrlist {
+	__s32	al_count;	/* number of entries in attrlist */
+	__s32	al_more;	/* T/F: more attrs (do call again) */
+	__s32	al_offset[1];	/* byte offsets of attrs [var-sized] */
+};
+
+struct xfs_attrlist_ent {	/* data from attr_list() */
+	__u32	a_valuelen;	/* number bytes in value of attr */
+	char	a_name[1];	/* attr name (NULL terminated) */
+};
+
 typedef struct xfs_fsop_attrlist_handlereq {
 	struct xfs_fsop_handlereq	hreq; /* handle interface structure */
 	struct xfs_attrlist_cursor	pos; /* opaque cookie, list offset */