linux-kernel - [PATCH 4.19 78/97] Btrfs: fix btrfs_wait_ordered_range() so that it waits for all ordered extents

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Message-Id: <20200227132227.200104132@linuxfoundation.org>
Date:   Thu, 27 Feb 2020 14:37:26 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Qu Wenruo <wqu@...e.com>,
        Josef Bacik <josef@...icpanda.com>,
        Filipe Manana <fdmanana@...e.com>,
        David Sterba <dsterba@...e.com>
Subject: [PATCH 4.19 78/97] Btrfs: fix btrfs_wait_ordered_range() so that it waits for all ordered extents

From: Filipe Manana <fdmanana@...e.com>

commit e75fd33b3f744f644061a4f9662bd63f5434f806 upstream.

In btrfs_wait_ordered_range() once we find an ordered extent that has
finished with an error we exit the loop and don't wait for any other
ordered extents that might be still in progress.

All the users of btrfs_wait_ordered_range() expect that there are no more
ordered extents in progress after that function returns. So past fixes
such like the ones from the two following commits:

  ff612ba7849964 ("btrfs: fix panic during relocation after ENOSPC before
                   writeback happens")

  28aeeac1dd3080 ("Btrfs: fix panic when starting bg cache writeout after
                   IO error")

don't work when there are multiple ordered extents in the range.

Fix that by making btrfs_wait_ordered_range() wait for all ordered extents
even after it finds one that had an error.

Link: https://github.com/kdave/btrfs-progs/issues/228#issuecomment-569777554
CC: stable@...r.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <wqu@...e.com>
Reviewed-by: Josef Bacik <josef@...icpanda.com>
Signed-off-by: Filipe Manana <fdmanana@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/btrfs/ordered-data.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -712,10 +712,15 @@ int btrfs_wait_ordered_range(struct inod
 		}
 		btrfs_start_ordered_extent(inode, ordered, 1);
 		end = ordered->file_offset;
+		/*
+		 * If the ordered extent had an error save the error but don't
+		 * exit without waiting first for all other ordered extents in
+		 * the range to complete.
+		 */
 		if (test_bit(BTRFS_ORDERED_IOERR, &ordered->flags))
 			ret = -EIO;
 		btrfs_put_ordered_extent(ordered);
-		if (ret || end == 0 || end == start)
+		if (end == 0 || end == start)
 			break;
 		end--;
 	}