linux-kernel - [PATCH AUTOSEL 5.13 170/219] btrfs: reset this_bio

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Date:   Thu,  9 Sep 2021 07:45:46 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Qu Wenruo <wqu@...e.com>, Anand Jain <anand.jain@...cle.com>,
        David Sterba <dsterba@...e.com>,
        Sasha Levin <sashal@...nel.org>, linux-btrfs@...r.kernel.org
Subject: [PATCH AUTOSEL 5.13 170/219] btrfs: reset this_bio_flag to avoid inheriting old flags

From: Qu Wenruo <wqu@...e.com>

[ Upstream commit 4c37a7938496756649096a7ec26320eb8b0d90fb ]

In btrfs_do_readpage(), we never reset @this_bio_flag after we hit a
compressed extent.

This is fine, as for PAGE_SIZE == sectorsize case, we can only have one
sector for one page, thus @this_bio_flag will only be set at most once.

But for subpage case, after hitting a compressed extent, @this_bio_flag
will always have EXTENT_BIO_COMPRESSED bit, even we're reading a regular
extent.

This will lead to various read errors, and causing new ASSERT() in
incoming subpage patches, which adds more strict check in
btrfs_submit_compressed_read().

Fix it by declaring @this_bio_flag inside the main loop and reset its
value for each iteration.

Reviewed-by: Anand Jain <anand.jain@...cle.com>
Signed-off-by: Qu Wenruo <wqu@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/btrfs/extent_io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index dee2dafbc872..d760d328673b 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3400,7 +3400,6 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
 	size_t pg_offset = 0;
 	size_t iosize;
 	size_t blocksize = inode->i_sb->s_blocksize;
-	unsigned long this_bio_flag = 0;
 	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
 
 	ret = set_page_extent_mapped(page);
@@ -3431,6 +3430,7 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
 	}
 	begin_page_read(fs_info, page);
 	while (cur <= end) {
+		unsigned long this_bio_flag = 0;
 		bool force_bio_submit = false;
 		u64 disk_bytenr;
 
-- 
2.30.2