md/bitmap: improve handling of 'allclean'.
The 'allclean' flag is used to cache the fact that there is nothing to
do, so we can avoid waking up and scanning the bitmap regularly.
The two sorts of pages that might need the attention of the bitmap
daemon are BITMAP_PAGE_PENDING and BITMAP_PAGE_NEEDWRITE pages.
So make sure allclean reflects exactly when there are none of those.
So:
set it before scanning all pages with either bit set.
clear it whenever these bits are set
clear it when we desire not to clear one of these bits.
don't clear it any other time.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 69a6f25..689623c 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1146,6 +1146,7 @@
for (i = 0; i < bitmap->file_pages; i++)
set_page_attr(bitmap, bitmap->filemap[i],
BITMAP_PAGE_NEEDWRITE);
+ bitmap->allclean = 0;
}
static void bitmap_count_page(struct bitmap *bitmap, sector_t offset, int inc)
@@ -1211,10 +1212,8 @@
clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
spin_unlock_irqrestore(&bitmap->lock, flags);
- if (need_write) {
+ if (need_write)
write_page(bitmap, page, 0);
- bitmap->allclean = 0;
- }
spin_lock_irqsave(&bitmap->lock, flags);
j |= (PAGE_BITS - 1);
continue;
@@ -1222,12 +1221,16 @@
/* grab the new page, sync and release the old */
if (lastpage != NULL) {
- if (test_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE)) {
- clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
+ if (test_page_attr(bitmap, lastpage,
+ BITMAP_PAGE_NEEDWRITE)) {
+ clear_page_attr(bitmap, lastpage,
+ BITMAP_PAGE_NEEDWRITE);
spin_unlock_irqrestore(&bitmap->lock, flags);
write_page(bitmap, lastpage, 0);
} else {
- set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
+ set_page_attr(bitmap, lastpage,
+ BITMAP_PAGE_NEEDWRITE);
+ bitmap->allclean = 0;
spin_unlock_irqrestore(&bitmap->lock, flags);
}
} else
@@ -1250,6 +1253,8 @@
spin_lock_irqsave(&bitmap->lock, flags);
if (!bitmap->need_sync)
clear_page_attr(bitmap, page, BITMAP_PAGE_PENDING);
+ else
+ bitmap->allclean = 0;
}
bmc = bitmap_get_counter(bitmap,
(sector_t)j << CHUNK_BLOCK_SHIFT(bitmap),
@@ -1257,8 +1262,6 @@
if (!bmc)
j |= PAGE_COUNTER_MASK;
else if (*bmc) {
- bitmap->allclean = 0;
-
if (*bmc == 1 && !bitmap->need_sync) {
/* we can clear the bit */
*bmc = 0;
@@ -1280,6 +1283,7 @@
} else if (*bmc <= 2) {
*bmc = 1; /* maybe clear the bit next time */
set_page_attr(bitmap, page, BITMAP_PAGE_PENDING);
+ bitmap->allclean = 0;
}
}
}
@@ -1294,6 +1298,7 @@
write_page(bitmap, lastpage, 0);
} else {
set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
+ bitmap->allclean = 0;
spin_unlock_irqrestore(&bitmap->lock, flags);
}
}
@@ -1407,7 +1412,6 @@
else
sectors = 0;
}
- bitmap->allclean = 0;
return 0;
}
EXPORT_SYMBOL(bitmap_startwrite);
@@ -1453,13 +1457,14 @@
wake_up(&bitmap->overflow_wait);
(*bmc)--;
- if (*bmc <= 2)
+ if (*bmc <= 2) {
set_page_attr(bitmap,
filemap_get_page(
bitmap,
offset >> CHUNK_BLOCK_SHIFT(bitmap)),
BITMAP_PAGE_PENDING);
-
+ bitmap->allclean = 0;
+ }
spin_unlock_irqrestore(&bitmap->lock, flags);
offset += blocks;
if (sectors > blocks)
@@ -1495,7 +1500,6 @@
}
}
spin_unlock_irq(&bitmap->lock);
- bitmap->allclean = 0;
return rv;
}
@@ -1543,15 +1547,16 @@
if (!NEEDED(*bmc) && aborted)
*bmc |= NEEDED_MASK;
else {
- if (*bmc <= 2)
+ if (*bmc <= 2) {
set_page_attr(bitmap,
filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
BITMAP_PAGE_PENDING);
+ bitmap->allclean = 0;
+ }
}
}
unlock:
spin_unlock_irqrestore(&bitmap->lock, flags);
- bitmap->allclean = 0;
}
EXPORT_SYMBOL(bitmap_end_sync);
@@ -1623,9 +1628,9 @@
bitmap_count_page(bitmap, offset, 1);
page = filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap));
set_page_attr(bitmap, page, BITMAP_PAGE_PENDING);
+ bitmap->allclean = 0;
}
spin_unlock_irq(&bitmap->lock);
- bitmap->allclean = 0;
}
/* dirty the memory and file bits for bitmap chunks "s" to "e" */