diff options
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 872cca54cc6c..7620d335f1ec 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2116,7 +2116,27 @@ retry: continue; } - if (wbc->sync_mode != WB_SYNC_NONE) { + /* + * For subpage case, compression can lead to mixed + * writeback and dirty flags, e.g: + * 0 32K 64K 96K 128K + * | |//////||/////| |//| + * + * In above case, [32K, 96K) is asynchronously submitted + * for compression, and [124K, 128K) needs to be written back. + * + * If we didn't wait wrtiteback for page 64K, [128K, 128K) + * won't be submitted as the page still has writeback flag + * and will be skipped in the next check. + * + * This mixed writeback and dirty case is only possible for + * subpage case. + * + * TODO: Remove this check after migrating compression to + * regular submission. + */ + if (wbc->sync_mode != WB_SYNC_NONE || + btrfs_is_subpage(inode_to_fs_info(inode), mapping)) { if (folio_test_writeback(folio)) submit_write_bio(bio_ctrl, 0); folio_wait_writeback(folio); |