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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Qu Wenruo <wqu@suse.com>,
        Nikolay Borisov <nborisov@suse.com>,
        David Sterba <dsterba@suse.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 729/779] btrfs: properly flag filesystem with BTRFS_FEATURE_INCOMPAT_BIG_METADATA
Date:   Mon, 15 Aug 2022 20:06:13 +0200
Message-Id: <20220815180408.608022252@linuxfoundation.org>
In-Reply-To: <20220815180337.130757997@linuxfoundation.org>
References: <20220815180337.130757997@linuxfoundation.org>
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From: Nikolay Borisov <nborisov@suse.com>

[ Upstream commit e26b04c4c91925dba57324db177a24e18e2d0013 ]

Commit 6f93e834fa7c seemingly inadvertently moved the code responsible
for flagging the filesystem as having BIG_METADATA to a place where
setting the flag was essentially lost. This means that
filesystems created with kernels containing this bug (starting with 5.15)
can potentially be mounted by older (pre-3.4) kernels. In reality
chances for this happening are low because there are other incompat
flags introduced in the mean time. Still the correct behavior is to set
INCOMPAT_BIG_METADATA flag and persist this in the superblock.

Fixes: 6f93e834fa7c ("btrfs: fix upper limit for max_inline for page size 64K")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/disk-io.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 383e9c861306..e65c3039caf1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3337,16 +3337,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	 */
 	fs_info->compress_type = BTRFS_COMPRESS_ZLIB;
 
-	/*
-	 * Flag our filesystem as having big metadata blocks if they are bigger
-	 * than the page size.
-	 */
-	if (btrfs_super_nodesize(disk_super) > PAGE_SIZE) {
-		if (!(features & BTRFS_FEATURE_INCOMPAT_BIG_METADATA))
-			btrfs_info(fs_info,
-				"flagging fs with big metadata feature");
-		features |= BTRFS_FEATURE_INCOMPAT_BIG_METADATA;
-	}
 
 	/* Set up fs_info before parsing mount options */
 	nodesize = btrfs_super_nodesize(disk_super);
@@ -3387,6 +3377,17 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	if (features & BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)
 		btrfs_info(fs_info, "has skinny extents");
 
+	/*
+	 * Flag our filesystem as having big metadata blocks if they are bigger
+	 * than the page size.
+	 */
+	if (btrfs_super_nodesize(disk_super) > PAGE_SIZE) {
+		if (!(features & BTRFS_FEATURE_INCOMPAT_BIG_METADATA))
+			btrfs_info(fs_info,
+				"flagging fs with big metadata feature");
+		features |= BTRFS_FEATURE_INCOMPAT_BIG_METADATA;
+	}
+
 	/*
 	 * mixed block groups end up with duplicate but slightly offset
 	 * extent buffers for the same range.  It leads to corruptions
-- 
2.35.1