ext4: cleanup transaction restarts during inode deletion

During inode deletion, the number of journal credits that will be
needed is hard to determine.  For that reason we have journal
extend/restart calls in several places.  Whenever a transaction is
restarted, filesystem must be in a consistent state because there is
no atomicity guarantee beyond a restart call.

Add ext4_xattr_ensure_credits() helper function which takes care of
journal extend/restart logic.  It also handles getting jbd2 write
access and dirty metadata calls.  This function is called at every
iteration of handling an ea_inode reference.

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/inode.c

@@ -239,7 +239,11 @@ void ext4_evict_inode(struct inode *inode)
 	 */
 	sb_start_intwrite(inode->i_sb);
 
-	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, extra_credits);
+	if (!IS_NOQUOTA(inode))
+		extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb);
+
+	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
+				 ext4_blocks_for_truncate(inode)+extra_credits);
 	if (IS_ERR(handle)) {
 		ext4_std_error(inode->i_sb, PTR_ERR(handle));
 		/*
@@ -251,36 +255,9 @@ void ext4_evict_inode(struct inode *inode)
 		sb_end_intwrite(inode->i_sb);
 		goto no_delete;
 	}
+
 	if (IS_SYNC(inode))
 		ext4_handle_sync(handle);
-
-	/*
-	 * Delete xattr inode before deleting the main inode.
-	 */
-	err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array);
-	if (err) {
-		ext4_warning(inode->i_sb,
-			     "couldn't delete inode's xattr (err %d)", err);
-		goto stop_handle;
-	}
-
-	if (!IS_NOQUOTA(inode))
-		extra_credits += 2 * EXT4_QUOTA_DEL_BLOCKS(inode->i_sb);
-
-	if (!ext4_handle_has_enough_credits(handle,
-			ext4_blocks_for_truncate(inode) + extra_credits)) {
-		err = ext4_journal_extend(handle,
-			ext4_blocks_for_truncate(inode) + extra_credits);
-		if (err > 0)
-			err = ext4_journal_restart(handle,
-			ext4_blocks_for_truncate(inode) + extra_credits);
-		if (err != 0) {
-			ext4_warning(inode->i_sb,
-				     "couldn't extend journal (err %d)", err);
-			goto stop_handle;
-		}
-	}
-
 	inode->i_size = 0;
 	err = ext4_mark_inode_dirty(handle, inode);
 	if (err) {
@@ -298,25 +275,17 @@ void ext4_evict_inode(struct inode *inode)
 		}
 	}
 
-	/*
-	 * ext4_ext_truncate() doesn't reserve any slop when it
-	 * restarts journal transactions; therefore there may not be
-	 * enough credits left in the handle to remove the inode from
-	 * the orphan list and set the dtime field.
-	 */
-	if (!ext4_handle_has_enough_credits(handle, extra_credits)) {
-		err = ext4_journal_extend(handle, extra_credits);
-		if (err > 0)
-			err = ext4_journal_restart(handle, extra_credits);
-		if (err != 0) {
-			ext4_warning(inode->i_sb,
-				     "couldn't extend journal (err %d)", err);
-		stop_handle:
-			ext4_journal_stop(handle);
-			ext4_orphan_del(NULL, inode);
-			sb_end_intwrite(inode->i_sb);
-			goto no_delete;
-		}
+	/* Remove xattr references. */
+	err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array,
+				      extra_credits);
+	if (err) {
+		ext4_warning(inode->i_sb, "xattr delete (err %d)", err);
+stop_handle:
+		ext4_journal_stop(handle);
+		ext4_orphan_del(NULL, inode);
+		sb_end_intwrite(inode->i_sb);
+		ext4_xattr_inode_array_free(ea_inode_array);
+		goto no_delete;
 	}
 
 	/*
@@ -342,7 +311,6 @@ void ext4_evict_inode(struct inode *inode)
 		ext4_clear_inode(inode);
 	else
 		ext4_free_inode(handle, inode);
-
 	ext4_journal_stop(handle);
 	sb_end_intwrite(inode->i_sb);
 	ext4_xattr_inode_array_free(ea_inode_array);