Directory xattr znodes hold a reference on their parent

[zfs.git] / module / zfs / zfs_acl.c

diff --git a/module/zfs/zfs_acl.c b/module/zfs/zfs_acl.c
index 98c0019..db6331e 100644 (file)
--- a/module/zfs/zfs_acl.c
+++ b/module/zfs/zfs_acl.c
@@ -2453,32 +2453,52 @@ zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr)
 {
        uint32_t        working_mode;
        int             error;
-       int             is_attr;
        boolean_t       check_privs;
-       znode_t         *xzp;
        znode_t         *check_zp = zp;
        mode_t          needed_bits;
        uid_t           owner;
 
-       is_attr = ((zp->z_pflags & ZFS_XATTR) && S_ISDIR(ZTOI(zp)->i_mode));
-
        /*
         * If attribute then validate against base file
         */
-       if (is_attr) {
+       if ((zp->z_pflags & ZFS_XATTR) && S_ISDIR(ZTOI(zp)->i_mode)) {
                uint64_t        parent;
 
-               if ((error = sa_lookup(zp->z_sa_hdl,
-                   SA_ZPL_PARENT(ZTOZSB(zp)), &parent,
-                   sizeof (parent))) != 0)
-                       return (error);
+               rw_enter(&zp->z_xattr_lock, RW_READER);
+               if (zp->z_xattr_parent) {
+                       check_zp = zp->z_xattr_parent;
+                       rw_exit(&zp->z_xattr_lock);
 
-               if ((error = zfs_zget(ZTOZSB(zp),
-                   parent, &xzp)) != 0)        {
-                       return (error);
-               }
+                       /*
+                        * Verify a lookup yields the same znode.
+                        */
+                       ASSERT3S(sa_lookup(zp->z_sa_hdl, SA_ZPL_PARENT(
+                           ZTOZSB(zp)), &parent, sizeof (parent)), ==, 0);
+                       ASSERT3U(check_zp->z_id, ==, parent);
+               } else {
+                       rw_exit(&zp->z_xattr_lock);
 
-               check_zp = xzp;
+                       error = sa_lookup(zp->z_sa_hdl, SA_ZPL_PARENT(
+                           ZTOZSB(zp)), &parent, sizeof (parent));
+                       if (error)
+                               return (error);
+
+                       /*
+                        * Cache the lookup on the parent file znode as
+                        * zp->z_xattr_parent and hold a reference.  This
+                        * effectively pins the parent in memory until all
+                        * child xattr znodes have been destroyed and
+                        * release their references in zfs_inode_destroy().
+                        */
+                       error = zfs_zget(ZTOZSB(zp), parent, &check_zp);
+                       if (error)
+                               return (error);
+
+                       rw_enter(&zp->z_xattr_lock, RW_WRITER);
+                       if (zp->z_xattr_parent == NULL)
+                               zp->z_xattr_parent = check_zp;
+                       rw_exit(&zp->z_xattr_lock);
+               }
 
                /*
                 * fixup mode to map to xattr perms
@@ -2521,15 +2541,11 @@ zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr)
 
        if ((error = zfs_zaccess_common(check_zp, mode, &working_mode,
            &check_privs, skipaclchk, cr)) == 0) {
-               if (is_attr)
-                       iput(ZTOI(xzp));
                return (secpolicy_vnode_access2(cr, ZTOI(zp), owner,
                    needed_bits, needed_bits));
        }
 
        if (error && !check_privs) {
-               if (is_attr)
-                       iput(ZTOI(xzp));
                return (error);
        }
 
@@ -2590,10 +2606,6 @@ zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr)
                    needed_bits, needed_bits);
        }
 
-
-       if (is_attr)
-               iput(ZTOI(xzp));
-
        return (error);
 }