From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Tue, 21 Dec 2021 04:44:50 +0000 (+0000)
Subject: iomap: Fix error handling in iomap_zero_iter()
X-Git-Tag: v6.6.17~8422^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9e05e95ca8dae8de4a7a1645014e1bbd9c8a4dab;p=platform%2Fkernel%2Flinux-rpi.git

iomap: Fix error handling in iomap_zero_iter()

iomap_write_end() does not return a negative errno to indicate an
error, but the number of bytes successfully copied.  It cannot return
an error today, so include a debugging assertion like the one in
iomap_unshare_iter().

Fixes: c6f40468657d ("fsdax: decouple zeroing from the iomap buffered I/O code")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211221044450.517558-1-willy@infradead.org
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index ac040d6..49279df 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -895,8 +895,8 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
 		mark_page_accessed(page);
 
 		bytes = iomap_write_end(iter, pos, bytes, bytes, page);
-		if (bytes < 0)
-			return bytes;
+		if (WARN_ON_ONCE(bytes == 0))
+			return -EIO;
 
 		pos += bytes;
 		length -= bytes;