btrfs: subpage: make reader lock utilize bitmap

[linux-2.6-microblaze.git] / fs / btrfs / subpage.h

diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index 97ba2c1..b6dc013 100644 (file)
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -33,7 +33,7 @@ struct btrfs_subpage_info {
        unsigned int total_nr_bits;
 
        /*
-        * *_start indicates where the bitmap starts, the length is always
+        * *_offset indicates where the bitmap starts, the length is always
         * @bitmap_size, which is calculated from PAGE_SIZE / sectorsize.
         */
        unsigned int uptodate_offset;
@@ -41,6 +41,16 @@ struct btrfs_subpage_info {
        unsigned int writeback_offset;
        unsigned int ordered_offset;
        unsigned int checked_offset;
+
+       /*
+        * For locked bitmaps, normally it's subpage representation for folio
+        * Locked flag, but metadata is different:
+        *
+        * - Metadata doesn't really lock the folio
+        *   It's just to prevent page::private get cleared before the last
+        *   end_page_read().
+        */
+       unsigned int locked_offset;
 };
 
 /*