md/bitmap: rename and tidy up BITMAP_PAGE_CLEAN

The flag 'BITMAP_PAGE_CLEAN' has a confusing name as it doesn't mean
that the page is clean, but rather that there are counters in the page
which allow bits in the bitmap to be cleared - i.e. maybe cleaning can
happen.

So change it to BITMAP_PAGE_PENDING and fix some irregularities:
 - Don't set it in bitmap_init_from_disk as bitmap_set_memory_bits
   sets it when needed
 - in bitmap_daemon_work, if we find a counter that is '1', but
   need_sync is set, then set BITMAP_PAGE_PENDING again (it was
   recently cleared) to ensure we don't forget about this bit.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 0dc6546..69a6f25 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -868,7 +868,8 @@ static void bitmap_file_kick(struct bitmap *bitmap)
 
 enum bitmap_page_attr {
        BITMAP_PAGE_DIRTY = 0,     /* there are set bits that need to be synced */
-       BITMAP_PAGE_CLEAN = 1,     /* there are bits that might need to be cleared */
+       BITMAP_PAGE_PENDING = 1,   /* there are bits that are being cleaned.
+                                   * i.e. counter is 1 or 2. */
        BITMAP_PAGE_NEEDWRITE = 2, /* there are cleared bits that need to be synced */
 };
 
@@ -1111,7 +1112,6 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
                                               (sector_t)i << CHUNK_BLOCK_SHIFT(bitmap),
                                               needed);
                        bit_cnt++;
-                       set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
                }
        }
 
@@ -1204,7 +1204,7 @@ void bitmap_daemon_work(mddev_t *mddev)
 
                if (page != lastpage) {
                        /* skip this page unless it's marked as needing cleaning */
-                       if (!test_page_attr(bitmap, page, BITMAP_PAGE_CLEAN)) {
+                       if (!test_page_attr(bitmap, page, BITMAP_PAGE_PENDING)) {
                                int need_write = test_page_attr(bitmap, page,
                                                                BITMAP_PAGE_NEEDWRITE);
                                if (need_write)
@@ -1249,19 +1249,17 @@ void bitmap_daemon_work(mddev_t *mddev)
                        }
                        spin_lock_irqsave(&bitmap->lock, flags);
                        if (!bitmap->need_sync)
-                               clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
+                               clear_page_attr(bitmap, page, BITMAP_PAGE_PENDING);
                }
                bmc = bitmap_get_counter(bitmap,
                                         (sector_t)j << CHUNK_BLOCK_SHIFT(bitmap),
                                         &blocks, 0);
-               if (bmc) {
-                       if (*bmc)
-                               bitmap->allclean = 0;
+               if (!bmc)
+                       j |= PAGE_COUNTER_MASK;
+               else if (*bmc) {
+                       bitmap->allclean = 0;
 
-                       if (*bmc == 2) {
-                               *bmc = 1; /* maybe clear the bit next time */
-                               set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
-                       } else if (*bmc == 1 && !bitmap->need_sync) {
+                       if (*bmc == 1 && !bitmap->need_sync) {
                                /* we can clear the bit */
                                *bmc = 0;
                                bitmap_count_page(bitmap,
@@ -1275,13 +1273,15 @@ void bitmap_daemon_work(mddev_t *mddev)
                                                  paddr);
                                else
                                        __clear_bit_le(
-                                                       file_page_offset(bitmap,
-                                                                        j),
-                                                       paddr);
+                                               file_page_offset(bitmap,
+                                                                j),
+                                               paddr);
                                kunmap_atomic(paddr, KM_USER0);
+                       } else if (*bmc <= 2) {
+                               *bmc = 1; /* maybe clear the bit next time */
+                               set_page_attr(bitmap, page, BITMAP_PAGE_PENDING);
                        }
-               } else
-                       j |= PAGE_COUNTER_MASK;
+               }
        }
        spin_unlock_irqrestore(&bitmap->lock, flags);
 
@@ -1458,7 +1458,7 @@ void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long secto
                                      filemap_get_page(
                                              bitmap,
                                              offset >> CHUNK_BLOCK_SHIFT(bitmap)),
-                                     BITMAP_PAGE_CLEAN);
+                                     BITMAP_PAGE_PENDING);
 
                spin_unlock_irqrestore(&bitmap->lock, flags);
                offset += blocks;
@@ -1546,7 +1546,7 @@ void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, i
                        if (*bmc <= 2)
                                set_page_attr(bitmap,
                                              filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
-                                             BITMAP_PAGE_CLEAN);
+                                             BITMAP_PAGE_PENDING);
                }
        }
  unlock:
@@ -1622,7 +1622,7 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int n
                *bmc = 1 | (needed ? NEEDED_MASK : 0);
                bitmap_count_page(bitmap, offset, 1);
                page = filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap));
-               set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
+               set_page_attr(bitmap, page, BITMAP_PAGE_PENDING);
        }
        spin_unlock_irq(&bitmap->lock);
        bitmap->allclean = 0;