udf: Do not update file length for failed writes to inline files

commit 256fe416 upstream.

When write to inline file fails (or happens only partly), we still
updated length of inline data as if the whole write succeeded. Fix the
update of length of inline data to happen only if the write succeeds.

Reported-by:  <syzbot+0937935b993956ba28ab@syzkaller.appspotmail.com>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/udf/file.c

@@ -149,26 +149,24 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		goto out;
 
 	down_write(&iinfo->i_data_sem);
-	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
-		loff_t end = iocb->ki_pos + iov_iter_count(from);
-
-		if (inode->i_sb->s_blocksize <
-				(udf_file_entry_alloc_offset(inode) + end)) {
-			err = udf_expand_file_adinicb(inode);
-			if (err) {
-				inode_unlock(inode);
-				udf_debug("udf_expand_adinicb: err=%d\n", err);
-				return err;
-			}
-		} else {
-			iinfo->i_lenAlloc = max(end, inode->i_size);
-			up_write(&iinfo->i_data_sem);
+	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB &&
+	    inode->i_sb->s_blocksize < (udf_file_entry_alloc_offset(inode) +
+				 iocb->ki_pos + iov_iter_count(from))) {
+		err = udf_expand_file_adinicb(inode);
+		if (err) {
+			inode_unlock(inode);
+			udf_debug("udf_expand_adinicb: err=%d\n", err);
+			return err;
 		}
 	} else
 		up_write(&iinfo->i_data_sem);
 
 	retval = __generic_file_write_iter(iocb, from);
 out:
+	down_write(&iinfo->i_data_sem);
+	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB && retval > 0)
+		iinfo->i_lenAlloc = inode->i_size;
+	up_write(&iinfo->i_data_sem);
 	inode_unlock(inode);
 
 	if (retval > 0) {