Using e.g. set_bit instead of __set_bit and using test_and_clear_bit
allow us to remove some locking and contract other locked ranges.
It is rare that we set or clear a lot of these bits, so gain should
outweigh any cost.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
drivers/md/bitmap.c | 55 +++++++++++++++++++++------------------------------
1 file changed, 23 insertions(+), 32 deletions(-)
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index d8e2591..c26100b 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -797,21 +797,27 @@ enum bitmap_page_attr {
static inline void set_page_attr(struct bitmap *bitmap, int pnum,
enum bitmap_page_attr attr)
{
- __set_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
+ set_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
}
static inline void clear_page_attr(struct bitmap *bitmap, int pnum,
enum bitmap_page_attr attr)
{
- __clear_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
+ clear_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
}
-static inline unsigned long test_page_attr(struct bitmap *bitmap, int pnum,
- enum bitmap_page_attr attr)
+static inline int test_page_attr(struct bitmap *bitmap, int pnum,
+ enum bitmap_page_attr attr)
{
return test_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
}
+static inline int test_and_clear_page_attr(struct bitmap *bitmap, int pnum,
+ enum bitmap_page_attr attr)
+{
+ return test_and_clear_bit((pnum<<2) + attr,
+ bitmap->storage.filemap_attr);
+}
/*
* bitmap_file_set_bit -- called before performing a write to the md device
* to set (and eventually sync) a particular bit in the bitmap file
@@ -882,23 +888,17 @@ void bitmap_unplug(struct bitmap *bitmap)
/* look at each page to see if there are any set bits that need to be
* flushed out to disk */
for (i = 0; i < bitmap->storage.file_pages; i++) {
- spin_lock_irq(&bitmap->lock);
- if (!bitmap->storage.filemap) {
- spin_unlock_irq(&bitmap->lock);
+ if (!bitmap->storage.filemap)
return;
- }
- dirty = test_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
- need_write = test_page_attr(bitmap, i, BITMAP_PAGE_NEEDWRITE);
- clear_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
- clear_page_attr(bitmap, i, BITMAP_PAGE_NEEDWRITE);
- if (dirty || need_write)
+ dirty = test_and_clear_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
+ need_write = test_and_clear_page_attr(bitmap, i,
+ BITMAP_PAGE_NEEDWRITE);
+ if (dirty || need_write) {
clear_page_attr(bitmap, i, BITMAP_PAGE_PENDING);
+ write_page(bitmap, bitmap->storage.filemap[i], 0);
+ }
if (dirty)
wait = 1;
- spin_unlock_irq(&bitmap->lock);
-
- if (dirty || need_write)
- write_page(bitmap, bitmap->storage.filemap[i], 0);
}
if (wait) { /* if any writes were performed, we need to wait on them */
if (bitmap->storage.file)
@@ -1060,12 +1060,10 @@ void bitmap_write_all(struct bitmap *bitmap)
/* Only one copy, so nothing needed */
return;
- spin_lock_irq(&bitmap->lock);
for (i = 0; i < bitmap->storage.file_pages; i++)
set_page_attr(bitmap, i,
BITMAP_PAGE_NEEDWRITE);
bitmap->allclean = 0;
- spin_unlock_irq(&bitmap->lock);
}
static void bitmap_count_page(struct bitmap *bitmap, sector_t offset, int inc)
@@ -1126,15 +1124,11 @@ void bitmap_daemon_work(struct mddev *mddev)
* So set NEEDWRITE now, then after we make any last-minute changes
* we will write it.
*/
- spin_lock_irq(&bitmap->lock);
for (j = 0; j < bitmap->storage.file_pages; j++)
- if (test_page_attr(bitmap, j,
- BITMAP_PAGE_PENDING)) {
+ if (test_and_clear_page_attr(bitmap, j,
+ BITMAP_PAGE_PENDING))
set_page_attr(bitmap, j,
BITMAP_PAGE_NEEDWRITE);
- clear_page_attr(bitmap, j,
- BITMAP_PAGE_PENDING);
- }
if (bitmap->need_sync &&
mddev->bitmap_info.external == 0) {
@@ -1154,6 +1148,7 @@ void bitmap_daemon_work(struct mddev *mddev)
/* Now look at the bitmap counters and if any are '2' or '1',
* decrement and handle accordingly.
*/
+ spin_lock_irq(&bitmap->lock);
nextpage = 0;
for (j = 0; j < bitmap->chunks; j++) {
bitmap_counter_t *bmc;
@@ -1186,6 +1181,7 @@ void bitmap_daemon_work(struct mddev *mddev)
bitmap->allclean = 0;
}
}
+ spin_unlock_irq(&bitmap->lock);
/* Now start writeout on any page in NEEDWRITE that isn't DIRTY.
* DIRTY pages need to be written by bitmap_unplug so it can wait
@@ -1204,18 +1200,13 @@ void bitmap_daemon_work(struct mddev *mddev)
BITMAP_PAGE_DIRTY))
/* bitmap_unplug will handle the rest */
break;
- if (test_page_attr(bitmap, j,
- BITMAP_PAGE_NEEDWRITE)) {
- clear_page_attr(bitmap, j,
- BITMAP_PAGE_NEEDWRITE);
- spin_unlock_irq(&bitmap->lock);
+ if (test_and_clear_page_attr(bitmap, j,
+ BITMAP_PAGE_NEEDWRITE)) {
write_page(bitmap, bitmap->storage.filemap[j], 0);
- spin_lock_irq(&bitmap->lock);
if (!bitmap->storage.filemap)
break;
}
}
- spin_unlock_irq(&bitmap->lock);
done:
if (bitmap->allclean == 0)
--
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