From: NeilBrown Currently we don't wait for updates to the bitmap to be flushed to disk properly. The infrastructure all there, but it isn't being used.... A separate kernel thread (bitmap_writeback_daemon) is needed to wait for each page as we cannot get callbacks when a page write completes. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton --- 25-akpm/drivers/md/bitmap.c | 119 ++++++++++++++++-------------------- 25-akpm/include/linux/raid/bitmap.h | 13 --- 2 files changed, 55 insertions(+), 77 deletions(-) diff -puN drivers/md/bitmap.c~md-enable-the-bitmap-write-back-daemon-and-wait-for-it drivers/md/bitmap.c --- 25/drivers/md/bitmap.c~md-enable-the-bitmap-write-back-daemon-and-wait-for-it 2005-03-23 02:09:53.000000000 -0800 +++ 25-akpm/drivers/md/bitmap.c 2005-03-23 02:09:53.000000000 -0800 @@ -261,30 +261,33 @@ char *file_path(struct file *file, char /* * write out a page */ -static int write_page(struct page *page, int wait) +static int write_page(struct bitmap *bitmap, struct page *page, int wait) { int ret = -ENOMEM; lock_page(page); - if (page->mapping == NULL) - goto unlock_out; - else if (i_size_read(page->mapping->host) < page->index << PAGE_SHIFT) { - ret = -ENOENT; - goto unlock_out; - } - ret = page->mapping->a_ops->prepare_write(NULL, page, 0, PAGE_SIZE); if (!ret) ret = page->mapping->a_ops->commit_write(NULL, page, 0, PAGE_SIZE); if (ret) { -unlock_out: unlock_page(page); return ret; } set_page_dirty(page); /* force it to be written out */ + + if (!wait) { + /* add to list to be waited for by daemon */ + struct page_list *item = mempool_alloc(bitmap->write_pool, GFP_NOIO); + item->page = page; + page_cache_get(page); + spin_lock(&bitmap->write_lock); + list_add(&item->list, &bitmap->complete_pages); + spin_unlock(&bitmap->write_lock); + md_wakeup_thread(bitmap->writeback_daemon); + } return write_one_page(page, wait); } @@ -343,14 +346,13 @@ int bitmap_update_sb(struct bitmap *bitm spin_unlock_irqrestore(&bitmap->lock, flags); return 0; } - page_cache_get(bitmap->sb_page); spin_unlock_irqrestore(&bitmap->lock, flags); sb = (bitmap_super_t *)kmap(bitmap->sb_page); sb->events = cpu_to_le64(bitmap->mddev->events); if (!bitmap->mddev->degraded) sb->events_cleared = cpu_to_le64(bitmap->mddev->events); kunmap(bitmap->sb_page); - return write_page(bitmap->sb_page, 0); + return write_page(bitmap, bitmap->sb_page, 0); } /* print out the bitmap file superblock */ @@ -556,10 +558,10 @@ static void bitmap_file_unmap(struct bit static void bitmap_stop_daemons(struct bitmap *bitmap); /* dequeue the next item in a page list -- don't call from irq context */ -static struct page_list *dequeue_page(struct bitmap *bitmap, - struct list_head *head) +static struct page_list *dequeue_page(struct bitmap *bitmap) { struct page_list *item = NULL; + struct list_head *head = &bitmap->complete_pages; spin_lock(&bitmap->write_lock); if (list_empty(head)) @@ -573,23 +575,15 @@ out: static void drain_write_queues(struct bitmap *bitmap) { - struct list_head *queues[] = { &bitmap->complete_pages, NULL }; - struct list_head *head; struct page_list *item; - int i; - for (i = 0; queues[i]; i++) { - head = queues[i]; - while ((item = dequeue_page(bitmap, head))) { - page_cache_release(item->page); - mempool_free(item, bitmap->write_pool); - } + while ((item = dequeue_page(bitmap))) { + /* don't bother to wait */ + page_cache_release(item->page); + mempool_free(item, bitmap->write_pool); } - spin_lock(&bitmap->write_lock); - bitmap->writes_pending = 0; /* make sure waiters continue */ wake_up(&bitmap->write_wait); - spin_unlock(&bitmap->write_lock); } static void bitmap_file_put(struct bitmap *bitmap) @@ -734,13 +728,13 @@ int bitmap_unplug(struct bitmap *bitmap) spin_unlock_irqrestore(&bitmap->lock, flags); if (attr & (BITMAP_PAGE_DIRTY | BITMAP_PAGE_NEEDWRITE)) - if (write_page(page, 0)) + if (write_page(bitmap, page, 0)) return 1; } if (wait) { /* if any writes were performed, we need to wait on them */ spin_lock_irq(&bitmap->write_lock); wait_event_lock_irq(bitmap->write_wait, - bitmap->writes_pending == 0, bitmap->write_lock, + list_empty(&bitmap->complete_pages), bitmap->write_lock, wake_up_process(bitmap->writeback_daemon->tsk)); spin_unlock_irq(&bitmap->write_lock); } @@ -841,7 +835,7 @@ static int bitmap_init_from_disk(struct */ memset(page_address(page) + offset, 0xff, PAGE_SIZE - offset); - ret = write_page(page, 1); + ret = write_page(bitmap, page, 1); if (ret) { kunmap(page); /* release, page not in filemap yet */ @@ -934,7 +928,7 @@ int bitmap_daemon_work(struct bitmap *bi } spin_unlock_irqrestore(&bitmap->lock, flags); if (attr & BITMAP_PAGE_NEEDWRITE) { - if (write_page(page, 0)) + if (write_page(bitmap, page, 0)) bitmap_file_kick(bitmap); page_cache_release(page); } @@ -950,7 +944,7 @@ int bitmap_daemon_work(struct bitmap *bi if (get_page_attr(bitmap, lastpage) & BITMAP_PAGE_NEEDWRITE) { clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE); spin_unlock_irqrestore(&bitmap->lock, flags); - err = write_page(lastpage, 0); + err = write_page(bitmap, lastpage, 0); } else { set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE); spin_unlock_irqrestore(&bitmap->lock, flags); @@ -998,7 +992,7 @@ int bitmap_daemon_work(struct bitmap *bi if (get_page_attr(bitmap, lastpage) &BITMAP_PAGE_NEEDWRITE) { clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE); spin_unlock_irqrestore(&bitmap->lock, flags); - err = write_page(lastpage, 0); + err = write_page(bitmap, lastpage, 0); } else { set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE); spin_unlock_irqrestore(&bitmap->lock, flags); @@ -1034,46 +1028,40 @@ static void bitmap_writeback_daemon(mdde struct page_list *item; int err = 0; - while (1) { - PRINTK("%s: bitmap writeback daemon waiting...\n", bmname(bitmap)); - down_interruptible(&bitmap->write_done); - if (signal_pending(current)) { - printk(KERN_INFO - "%s: bitmap writeback daemon got signal, exiting...\n", - bmname(bitmap)); - break; - } + if (signal_pending(current)) { + printk(KERN_INFO + "%s: bitmap writeback daemon got signal, exiting...\n", + bmname(bitmap)); + err = -EINTR; + goto out; + } - PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap)); - /* wait on bitmap page writebacks */ - while ((item = dequeue_page(bitmap, &bitmap->complete_pages))) { - page = item->page; - mempool_free(item, bitmap->write_pool); - PRINTK("wait on page writeback: %p %lu\n", page, bitmap->writes_pending); - wait_on_page_writeback(page); - PRINTK("finished page writeback: %p %lu\n", page, bitmap->writes_pending); - spin_lock(&bitmap->write_lock); - if (!--bitmap->writes_pending) - wake_up(&bitmap->write_wait); - spin_unlock(&bitmap->write_lock); - err = PageError(page); - page_cache_release(page); - if (err) { - printk(KERN_WARNING "%s: bitmap file writeback " - "failed (page %lu): %d\n", - bmname(bitmap), page->index, err); - bitmap_file_kick(bitmap); - goto out; - } + PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap)); + /* wait on bitmap page writebacks */ + while ((item = dequeue_page(bitmap))) { + page = item->page; + mempool_free(item, bitmap->write_pool); + PRINTK("wait on page writeback: %p\n", page); + wait_on_page_writeback(page); + PRINTK("finished page writeback: %p\n", page); + + err = PageError(page); + page_cache_release(page); + if (err) { + printk(KERN_WARNING "%s: bitmap file writeback " + "failed (page %lu): %d\n", + bmname(bitmap), page->index, err); + bitmap_file_kick(bitmap); + goto out; } } -out: + out: + wake_up(&bitmap->write_wait); if (err) { printk(KERN_INFO "%s: bitmap writeback daemon exiting (%d)\n", - bmname(bitmap), err); + bmname(bitmap), err); daemon_exit(bitmap, &bitmap->writeback_daemon); } - return; } static int bitmap_start_daemon(struct bitmap *bitmap, mdk_thread_t **ptr, @@ -1373,7 +1361,7 @@ int bitmap_setallbits(struct bitmap *bit spin_unlock_irqrestore(&bitmap->lock, flags); memset(kmap(page), 0xff, PAGE_SIZE); kunmap(page); - if (write_page(page, 0)) + if (write_page(bitmap, page, 0)) return 1; } @@ -1441,7 +1429,6 @@ int bitmap_create(mddev_t *mddev) mddev->bitmap = bitmap; spin_lock_init(&bitmap->write_lock); - init_MUTEX_LOCKED(&bitmap->write_done); INIT_LIST_HEAD(&bitmap->complete_pages); init_waitqueue_head(&bitmap->write_wait); bitmap->write_pool = mempool_create(WRITE_POOL_SIZE, write_pool_alloc, diff -puN include/linux/raid/bitmap.h~md-enable-the-bitmap-write-back-daemon-and-wait-for-it include/linux/raid/bitmap.h --- 25/include/linux/raid/bitmap.h~md-enable-the-bitmap-write-back-daemon-and-wait-for-it 2005-03-23 02:09:53.000000000 -0800 +++ 25-akpm/include/linux/raid/bitmap.h 2005-03-23 02:09:53.000000000 -0800 @@ -233,21 +233,12 @@ struct bitmap { unsigned long daemon_sleep; /* how many seconds between updates? */ /* - * bitmap write daemon - this daemon performs writes to the bitmap file - * this thread is only needed because of a limitation in ext3 (jbd) - * that does not allow a task to have two journal transactions ongoing - * simultaneously (even if the transactions are for two different - * filesystems) -- in the case of bitmap, that would be the filesystem - * that the bitmap file resides on and the filesystem that is mounted - * on the md device -- see current->journal_info in jbd/transaction.c + * bitmap_writeback_daemon waits for file-pages that have been written, + * as there is no way to get a call-back when a page write completes. */ mdk_thread_t *writeback_daemon; spinlock_t write_lock; - struct semaphore write_ready; - struct semaphore write_done; - unsigned long writes_pending; wait_queue_head_t write_wait; - struct list_head write_pages; struct list_head complete_pages; mempool_t *write_pool; }; _