From a2a72fbd1110323b2008dcb3ed14494957341dfe Mon Sep 17 00:00:00 2001
From: Qu Wenruo <wqu@suse.com>
Date: Wed, 20 Mar 2019 14:27:48 +0800
Patch-mainline: v5.2
Git-commit: a2a72fbd1110323b2008dcb3ed14494957341dfe
References: bsc#1168273
Subject: [PATCH 7/7] btrfs: extent_io: Handle errors better in
 extent_writepages()

We can only get <=0 from extent_write_cache_pages, add an ASSERT() for
it just in case.

Then instead of submitting the write bio even if we got some error,
check the return value first.
If we have already hit some error, just clean up the corrupted or
half-baked bio, and return error.

If there is no error so far, then call flush_write_bio() and return the
result.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/extent_io.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4222,7 +4222,6 @@ int extent_writepages(struct extent_io_t
 		      struct writeback_control *wbc)
 {
 	int ret = 0;
-	int flush_ret;
 	struct extent_page_data epd = {
 		.bio = NULL,
 		.tree = tree,
@@ -4231,8 +4230,12 @@ int extent_writepages(struct extent_io_t
 	};
 
 	ret = extent_write_cache_pages(mapping, wbc, &epd);
-	flush_ret = flush_write_bio(&epd);
-	BUG_ON(flush_ret < 0);
+	ASSERT(ret <= 0);
+	if (ret < 0) {
+		end_write_bio(&epd, ret);
+		return ret;
+	}
+	ret = flush_write_bio(&epd);
 	return ret;
 }