btrfs: zoned: fix critical section of relocation inode writeback

BugLink: https://bugs.launchpad.net/bugs/1989221
commit 19ab78ca86981e0e1e73036fb73a508731a7c078 upstream.

We use btrfs_zoned_data_reloc_{lock,unlock} to allow only one process to
write out to the relocation inode. That critical section must include all
the IO submission for the inode. However, flush_write_bio() in
extent_writepages() is out of the critical section, causing an IO
submission outside of the lock. This leads to an out of the order IO
submission and fail the relocation process.

Fix it by extending the critical section.

Fixes: 35156d852762 ("btrfs: zoned: only allow one process to add pages to a relocation inode")
CC: stable@vger.kernel.org # 5.16+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index b791e280af0ca012672c9d6313bfd0b49d3b15fb..a90546b3107c5098a286fc9df49723a28db6cd62 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5152,13 +5152,14 @@ int extent_writepages(struct address_space *mapping,
         */
        btrfs_zoned_data_reloc_lock(BTRFS_I(inode));
        ret = extent_write_cache_pages(mapping, wbc, &epd);
-       btrfs_zoned_data_reloc_unlock(BTRFS_I(inode));
        ASSERT(ret <= 0);
        if (ret < 0) {
+               btrfs_zoned_data_reloc_unlock(BTRFS_I(inode));
                end_write_bio(&epd, ret);
                return ret;
        }
        ret = flush_write_bio(&epd);
+       btrfs_zoned_data_reloc_unlock(BTRFS_I(inode));
        return ret;
 }