UBUNTU: SAUCE: (noup) Update zfs to 0.6.5.6-0ubuntu28

BugLink: https://launchpad.net/bugs/1839521

Sync ZFS 0.6.5.6-0ubuntu28 to Xenial:

Fix shrinker deadlock with xattrs (LP: #1839521)

Upstream ZFS fix 31b6111fd92a ("Kill zp->z_xattr_parent to prevent pinning")
and ddae16a9cf0b ("xattr dir doesn't get purged during iput") fix a deadlock
in shrinker path when a xattr directory inode and its xattr inode are in the
same disposal list and the xattr dir inode is evicted before the xattr inode.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

zfs/META

@@ -2,7 +2,7 @@ Meta:         1
 Name:         zfs
 Branch:       1.0
 Version:      0.6.5.6
-Release:      0ubuntu26
+Release:      0ubuntu28
 Release-Tags: relext
 License:      CDDL
 Author:       OpenZFS on Linux

zfs/include/sys/zfs_znode.h

@@ -209,7 +209,6 @@ typedef struct znode {
 	zfs_acl_t	*z_acl_cached;	/* cached acl */
 	krwlock_t	z_xattr_lock;	/* xattr data lock */
 	nvlist_t	*z_xattr_cached; /* cached xattrs */
-	struct znode	*z_xattr_parent; /* xattr parent znode */
 	list_node_t	z_link_node;	/* all znodes in fs link */
 	sa_handle_t	*z_sa_hdl;	/* handle to sa data */
 	boolean_t	z_is_sa;	/* are we native sa? */

zfs/module/zfs/zfs_acl.c

@@ -2473,53 +2473,33 @@ zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr)
 {
 	uint32_t	working_mode;
 	int		error;
-	boolean_t	check_privs;
-	znode_t		*check_zp = zp;
+	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 ((zp->z_pflags & ZFS_XATTR) && S_ISDIR(ZTOI(zp)->i_mode)) {
+	if (is_attr) {
 		uint64_t	parent;
 
-		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);
-
-			/*
-			 * 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);
-
-			error = sa_lookup(zp->z_sa_hdl, SA_ZPL_PARENT(
-			    ZTOZSB(zp)), &parent, sizeof (parent));
-			if (error)
-				return (error);
+		if ((error = sa_lookup(zp->z_sa_hdl,
+		    SA_ZPL_PARENT(ZTOZSB(zp)), &parent,
+		    sizeof (parent))) != 0)
+			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);
+		if ((error = zfs_zget(ZTOZSB(zp),
+		    parent, &xzp)) != 0)	{
+			return (error);
 		}
 
+		check_zp = xzp;
+
 		/*
 		 * fixup mode to map to xattr perms
 		 */
@@ -2561,11 +2541,15 @@ 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);
 	}
 
@@ -2626,6 +2610,9 @@ 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);
 }
 

zfs/module/zfs/zfs_dir.c

@@ -593,7 +593,7 @@ zfs_purgedir(znode_t *dzp)
 		if (error)
 			skipped += 1;
 		dmu_tx_commit(tx);
-
+		set_nlink(ZTOI(xzp), xzp->z_links);
 		zfs_iput_async(ZTOI(xzp));
 	}
 	zap_cursor_fini(&zc);
@@ -694,6 +694,7 @@ zfs_rmnode(znode_t *zp)
 		mutex_enter(&xzp->z_lock);
 		xzp->z_unlinked = B_TRUE;	/* mark xzp for deletion */
 		xzp->z_links = 0;	/* no more links to it */
+		set_nlink(ZTOI(xzp), 0); /* this will let iput purge us */
 		VERIFY(0 == sa_update(xzp->z_sa_hdl, SA_ZPL_LINKS(zsb),
 		    &xzp->z_links, sizeof (xzp->z_links), tx));
 		mutex_exit(&xzp->z_lock);

zfs/module/zfs/zfs_znode.c

@@ -120,7 +120,6 @@ zfs_znode_cache_constructor(void *buf, void *arg, int kmflags)
 	zp->z_dirlocks = NULL;
 	zp->z_acl_cached = NULL;
 	zp->z_xattr_cached = NULL;
-	zp->z_xattr_parent = NULL;
 	zp->z_moved = 0;
 	return (0);
 }
@@ -143,7 +142,6 @@ zfs_znode_cache_destructor(void *buf, void *arg)
 	ASSERT(zp->z_dirlocks == NULL);
 	ASSERT(zp->z_acl_cached == NULL);
 	ASSERT(zp->z_xattr_cached == NULL);
-	ASSERT(zp->z_xattr_parent == NULL);
 }
 
 static int
@@ -435,11 +433,6 @@ zfs_inode_destroy(struct inode *ip)
 		zp->z_xattr_cached = NULL;
 	}
 
-	if (zp->z_xattr_parent) {
-		zfs_iput_async(ZTOI(zp->z_xattr_parent));
-		zp->z_xattr_parent = NULL;
-	}
-
 	kmem_cache_free(znode_cache, zp);
 }
 
@@ -501,8 +494,7 @@ zfs_inode_set_ops(zfs_sb_t *zsb, struct inode *ip)
  */
 static znode_t *
 zfs_znode_alloc(zfs_sb_t *zsb, dmu_buf_t *db, int blksz,
-    dmu_object_type_t obj_type, uint64_t obj, sa_handle_t *hdl,
-    struct inode *dip)
+    dmu_object_type_t obj_type, uint64_t obj, sa_handle_t *hdl)
 {
 	znode_t	*zp;
 	struct inode *ip;
@@ -521,7 +513,6 @@ zfs_znode_alloc(zfs_sb_t *zsb, dmu_buf_t *db, int blksz,
 	ASSERT(zp->z_dirlocks == NULL);
 	ASSERT3P(zp->z_acl_cached, ==, NULL);
 	ASSERT3P(zp->z_xattr_cached, ==, NULL);
-	ASSERT3P(zp->z_xattr_parent, ==, NULL);
 	zp->z_moved = 0;
 	zp->z_sa_hdl = NULL;
 	zp->z_unlinked = 0;
@@ -560,14 +551,6 @@ zfs_znode_alloc(zfs_sb_t *zsb, dmu_buf_t *db, int blksz,
 
 	zp->z_mode = mode;
 
-	/*
-	 * xattr znodes hold a reference on their unique parent
-	 */
-	if (dip && zp->z_pflags & ZFS_XATTR) {
-		igrab(dip);
-		zp->z_xattr_parent = ITOZ(dip);
-	}
-
 	ip->i_ino = obj;
 	zfs_inode_update(zp);
 	zfs_inode_set_ops(zsb, ip);
@@ -913,8 +896,7 @@ zfs_mknode(znode_t *dzp, vattr_t *vap, dmu_tx_t *tx, cred_t *cr,
 	VERIFY(sa_replace_all_by_template(sa_hdl, sa_attrs, cnt, tx) == 0);
 
 	if (!(flag & IS_ROOT_NODE)) {
-		*zpp = zfs_znode_alloc(zsb, db, 0, obj_type, obj, sa_hdl,
-		    ZTOI(dzp));
+		*zpp = zfs_znode_alloc(zsb, db, 0, obj_type, obj, sa_hdl);
 		VERIFY(*zpp != NULL);
 		VERIFY(dzp != NULL);
 	} else {
@@ -1124,7 +1106,7 @@ zfs_zget(zfs_sb_t *zsb, uint64_t obj_num, znode_t **zpp)
 	 * bonus buffer.
 	 */
 	zp = zfs_znode_alloc(zsb, db, doi.doi_data_block_size,
-	    doi.doi_bonus_type, obj_num, NULL, NULL);
+	    doi.doi_bonus_type, obj_num, NULL);
 	if (zp == NULL) {
 		err = SET_ERROR(ENOENT);
 	} else {
@@ -1162,11 +1144,6 @@ zfs_rezget(znode_t *zp)
 		nvlist_free(zp->z_xattr_cached);
 		zp->z_xattr_cached = NULL;
 	}
-
-	if (zp->z_xattr_parent) {
-		zfs_iput_async(ZTOI(zp->z_xattr_parent));
-		zp->z_xattr_parent = NULL;
-	}
 	rw_exit(&zp->z_xattr_lock);
 
 	ASSERT(zp->z_sa_hdl == NULL);