xfs: increase number of ACL entries for V5 superblocks

The limit of 25 ACL entries is arbitrary, but baked into the on-disk
format.  For version 5 superblocks, increase it to the maximum nuber
of ACLs that can fit into a single xattr.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinuguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

(cherry picked from commit 5c87d4bc1a86bd6e6754ac3d6e111d776ddcfe57)

1 files changed, 24 insertions, 7 deletions

diff --git a/fs/xfs/xfs_acl.h b/fs/xfs/xfs_acl.h
index 39632d941354..4016a567b83c 100644
--- a/fs/xfs/xfs_acl.h
+++ b/fs/xfs/xfs_acl.h
@@ -22,19 +22,36 @@ struct inode;
 struct posix_acl;
 struct xfs_inode;
 
-#define XFS_ACL_MAX_ENTRIES 25
 #define XFS_ACL_NOT_PRESENT (-1)
 
 /* On-disk XFS access control list structure */
+struct xfs_acl_entry {
+        __be32  ae_tag;
+        __be32  ae_id;
+        __be16  ae_perm;
+        __be16  ae_pad;         /* fill the implicit hole in the structure */
+};
+
 struct xfs_acl {
-        __be32          acl_cnt;
-        struct xfs_acl_entry {
-                __be32  ae_tag;
-                __be32  ae_id;
-                __be16  ae_perm;
-        } acl_entry[XFS_ACL_MAX_ENTRIES];
+        __be32                  acl_cnt;
+        struct xfs_acl_entry    acl_entry[0];
 };
 
+/*
+ * The number of ACL entries allowed is defined by the on-disk format.
+ * For v4 superblocks, that is limited to 25 entries. For v5 superblocks, it is
+ * limited only by the maximum size of the xattr that stores the information.
+ */
+#define XFS_ACL_MAX_ENTRIES(mp) \
+        (xfs_sb_version_hascrc(&mp->m_sb) \
+                ?  (XATTR_SIZE_MAX - sizeof(struct xfs_acl)) / \
+                                                sizeof(struct xfs_acl_entry) \
+                : 25)
+
+#define XFS_ACL_MAX_SIZE(mp) \
+        (sizeof(struct xfs_acl) + \
+                sizeof(struct xfs_acl_entry) * XFS_ACL_MAX_ENTRIES((mp)))
+
 /* On-disk XFS extended attribute names */
 #define SGI_ACL_FILE            (unsigned char *)"SGI_ACL_FILE"
 #define SGI_ACL_DEFAULT         (unsigned char *)"SGI_ACL_DEFAULT"