From 856473cd5d17dbbf3055710857c67a4af6d9fcc0 Mon Sep 17 00:00:00 2001
From: Andreas Gruenbacher <agruenba@redhat.com>
Date: Mon, 6 Jul 2020 10:49:27 -0700
Subject: [PATCH] iomap: Make sure iomap_end is called after iomap_begin
Git-commit: 856473cd5d17dbbf3055710857c67a4af6d9fcc0
Patch-mainline: v5.9-rc1
References: bsc#1177754

Make sure iomap_end is always called when iomap_begin succeeds.

Without this fix, iomap_end won't be called when a filesystem's
iomap_begin operation returns an invalid mapping, bypassing any
unlocking done in iomap_end.  With this fix, the unlocking will still
happen.

This bug was found by Bob Peterson during code review.  It's unlikely
that such iomap_begin bugs will survive to affect users, so backporting
this fix seems unnecessary.

Fixes: ae259a9c8593 ("fs: introduce iomap infrastructure")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/iomap.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -63,10 +63,14 @@ iomap_apply(struct inode *inode, loff_t
 	ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
 	if (ret)
 		return ret;
-	if (WARN_ON(iomap.offset > pos))
-		return -EIO;
-	if (WARN_ON(iomap.length == 0))
-		return -EIO;
+	if (WARN_ON(iomap.offset > pos)) {
+		written = -EIO;
+		goto out;
+	}
+	if (WARN_ON(iomap.length == 0)) {
+		written = -EIO;
+		goto out;
+	}
 
 	/*
 	 * Cut down the length to the one actually provided by the filesystem,
@@ -82,6 +86,7 @@ iomap_apply(struct inode *inode, loff_t
 	 */
 	written = actor(inode, pos, length, data, &iomap);
 
+out:
 	/*
 	 * Now the data has been copied, commit the range we've copied.  This
 	 * should not fail unless the filesystem has had a fatal error.