From bdfd1140731a67c74fd74814f222c8078171adcd Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 22 May 2012 13:55:22 +1000 Subject: md/bitmap: make _page_attr bitops atomic. 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 --- drivers/md/bitmap.c | 55 ++++++++++++++++++++++------------------------------- 1 file changed, 23 insertions(+), 32 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index d2ab7d3df3ea..2e2f53cd5b21 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -799,21 +799,27 @@ 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 @@ -884,23 +890,17 @@ 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) @@ -1062,12 +1062,10 @@ 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) @@ -1128,15 +1126,11 @@ 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) { @@ -1156,6 +1150,7 @@ 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; @@ -1188,6 +1183,7 @@ 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 @@ -1206,16 +1202,11 @@ 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); } } - spin_unlock_irq(&bitmap->lock); done: if (bitmap->allclean == 0) -- cgit v1.2.3-55-g7522