ext4: fix check of inode in swap_inode_boot_loader

Before really do swap between inode and boot inode, something need to
check to avoid invalid or not permitted operation, like does this inode
has inline data. But the condition check should be protected by inode
lock to avoid change while swapping. Also some other condition will not
change between swapping, but there has no problem to do this under inode
lock.
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

fs/ext4/ioctl.c

@@ -116,15 +116,6 @@ static long swap_inode_boot_loader(struct super_block *sb,
 	struct inode *inode_bl;
 	struct ext4_inode_info *ei_bl;
 
-	if (inode->i_nlink != 1 || !S_ISREG(inode->i_mode) ||
-	    IS_SWAPFILE(inode) || IS_ENCRYPTED(inode) ||
-	    ext4_has_inline_data(inode))
-		return -EINVAL;
-
-	if (IS_RDONLY(inode) || IS_APPEND(inode) || IS_IMMUTABLE(inode) ||
-	    !inode_owner_or_capable(inode) || !capable(CAP_SYS_ADMIN))
-		return -EPERM;
-
 	inode_bl = ext4_iget(sb, EXT4_BOOT_LOADER_INO, EXT4_IGET_SPECIAL);
 	if (IS_ERR(inode_bl))
 		return PTR_ERR(inode_bl);
@@ -137,6 +128,19 @@ static long swap_inode_boot_loader(struct super_block *sb,
 	 * that only 1 swap_inode_boot_loader is running. */
 	lock_two_nondirectories(inode, inode_bl);
 
+	if (inode->i_nlink != 1 || !S_ISREG(inode->i_mode) ||
+	    IS_SWAPFILE(inode) || IS_ENCRYPTED(inode) ||
+	    ext4_has_inline_data(inode)) {
+		err = -EINVAL;
+		goto journal_err_out;
+	}
+
+	if (IS_RDONLY(inode) || IS_APPEND(inode) || IS_IMMUTABLE(inode) ||
+	    !inode_owner_or_capable(inode) || !capable(CAP_SYS_ADMIN)) {
+		err = -EPERM;
+		goto journal_err_out;
+	}
+
 	/* Wait for all existing dio workers */
 	inode_dio_wait(inode);
 	inode_dio_wait(inode_bl);