[PATCH] md/bitmap: remove bitmap writeback daemon
md/bitmap currently has a separate thread to wait for writes to the bitmap file to complete (as we cannot get a callback on that action). However this isn't needed as bitmap_unplug is called from process context and waits for the writeback thread to do it's work. The same result can be achieved by doing the waiting directly in bitmap_unplug. Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
NeilBrown
Linus Torvalds
parent
d7375ab324
commit
0b79ccf0cd
@ -7,7 +7,6 @@
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* additions, Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.:
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* - added disk storage for bitmap
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* - changes to allow various bitmap chunk sizes
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* - added bitmap daemon (to asynchronously clear bitmap bits from disk)
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*/
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/*
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@ -330,14 +329,13 @@ static int write_page(struct bitmap *bitmap, struct page *page, int wait)
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set_page_dirty(page); /* force it to be written out */
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if (!wait) {
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/* add to list to be waited for by daemon */
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/* add to list to be waited for */
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struct page_list *item = mempool_alloc(bitmap->write_pool, GFP_NOIO);
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item->page = page;
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get_page(page);
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spin_lock(&bitmap->write_lock);
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list_add(&item->list, &bitmap->complete_pages);
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spin_unlock(&bitmap->write_lock);
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md_wakeup_thread(bitmap->writeback_daemon);
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}
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return write_one_page(page, wait);
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}
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@ -621,8 +619,6 @@ static void bitmap_file_unmap(struct bitmap *bitmap)
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safe_put_page(sb_page);
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}
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static void bitmap_stop_daemon(struct bitmap *bitmap);
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/* dequeue the next item in a page list -- don't call from irq context */
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static struct page_list *dequeue_page(struct bitmap *bitmap)
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{
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@ -648,8 +644,6 @@ static void drain_write_queues(struct bitmap *bitmap)
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put_page(item->page);
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mempool_free(item, bitmap->write_pool);
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}
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wake_up(&bitmap->write_wait);
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}
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static void bitmap_file_put(struct bitmap *bitmap)
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@ -663,8 +657,6 @@ static void bitmap_file_put(struct bitmap *bitmap)
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bitmap->file = NULL;
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spin_unlock_irqrestore(&bitmap->lock, flags);
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bitmap_stop_daemon(bitmap);
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drain_write_queues(bitmap);
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bitmap_file_unmap(bitmap);
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@ -770,6 +762,8 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
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}
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static void bitmap_writeback(struct bitmap *bitmap);
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/* this gets called when the md device is ready to unplug its underlying
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* (slave) device queues -- before we let any writes go down, we need to
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* sync the dirty pages of the bitmap file to disk */
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@ -812,13 +806,9 @@ int bitmap_unplug(struct bitmap *bitmap)
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}
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}
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if (wait) { /* if any writes were performed, we need to wait on them */
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if (bitmap->file) {
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spin_lock_irq(&bitmap->write_lock);
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wait_event_lock_irq(bitmap->write_wait,
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list_empty(&bitmap->complete_pages), bitmap->write_lock,
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wake_up_process(bitmap->writeback_daemon->tsk));
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spin_unlock_irq(&bitmap->write_lock);
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} else
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if (bitmap->file)
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bitmap_writeback(bitmap);
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else
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md_super_wait(bitmap->mddev);
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}
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return 0;
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@ -1126,41 +1116,12 @@ int bitmap_daemon_work(struct bitmap *bitmap)
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return err;
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}
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static void daemon_exit(struct bitmap *bitmap, mdk_thread_t **daemon)
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static void bitmap_writeback(struct bitmap *bitmap)
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{
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mdk_thread_t *dmn;
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unsigned long flags;
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/* if no one is waiting on us, we'll free the md thread struct
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* and exit, otherwise we let the waiter clean things up */
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spin_lock_irqsave(&bitmap->lock, flags);
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if ((dmn = *daemon)) { /* no one is waiting, cleanup and exit */
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*daemon = NULL;
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spin_unlock_irqrestore(&bitmap->lock, flags);
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kfree(dmn);
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complete_and_exit(NULL, 0); /* do_exit not exported */
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}
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spin_unlock_irqrestore(&bitmap->lock, flags);
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}
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static void bitmap_writeback_daemon(mddev_t *mddev)
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{
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struct bitmap *bitmap = mddev->bitmap;
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struct page *page;
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struct page_list *item;
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int err = 0;
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if (signal_pending(current)) {
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printk(KERN_INFO
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"%s: bitmap writeback daemon got signal, exiting...\n",
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bmname(bitmap));
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err = -EINTR;
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goto out;
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}
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if (bitmap == NULL)
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/* about to be stopped. */
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return;
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PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap));
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/* wait on bitmap page writebacks */
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while ((item = dequeue_page(bitmap))) {
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@ -1177,59 +1138,9 @@ static void bitmap_writeback_daemon(mddev_t *mddev)
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"failed (page %lu): %d\n",
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bmname(bitmap), page->index, err);
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bitmap_file_kick(bitmap);
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goto out;
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break;
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}
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}
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out:
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wake_up(&bitmap->write_wait);
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if (err) {
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printk(KERN_INFO "%s: bitmap writeback daemon exiting (%d)\n",
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bmname(bitmap), err);
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daemon_exit(bitmap, &bitmap->writeback_daemon);
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}
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}
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static mdk_thread_t *bitmap_start_daemon(struct bitmap *bitmap,
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void (*func)(mddev_t *), char *name)
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{
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mdk_thread_t *daemon;
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char namebuf[32];
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#ifdef INJECT_FATAL_FAULT_2
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daemon = NULL;
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#else
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sprintf(namebuf, "%%s_%s", name);
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daemon = md_register_thread(func, bitmap->mddev, namebuf);
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#endif
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if (!daemon) {
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printk(KERN_ERR "%s: failed to start bitmap daemon\n",
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bmname(bitmap));
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return ERR_PTR(-ECHILD);
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}
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md_wakeup_thread(daemon); /* start it running */
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PRINTK("%s: %s daemon (pid %d) started...\n",
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bmname(bitmap), name, daemon->tsk->pid);
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return daemon;
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}
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static void bitmap_stop_daemon(struct bitmap *bitmap)
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{
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/* the daemon can't stop itself... it'll just exit instead... */
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if (bitmap->writeback_daemon && ! IS_ERR(bitmap->writeback_daemon) &&
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current->pid != bitmap->writeback_daemon->tsk->pid) {
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mdk_thread_t *daemon;
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unsigned long flags;
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spin_lock_irqsave(&bitmap->lock, flags);
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daemon = bitmap->writeback_daemon;
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bitmap->writeback_daemon = NULL;
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spin_unlock_irqrestore(&bitmap->lock, flags);
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if (daemon && ! IS_ERR(daemon))
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md_unregister_thread(daemon); /* destroy the thread */
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}
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}
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static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
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@ -1553,7 +1464,6 @@ int bitmap_create(mddev_t *mddev)
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spin_lock_init(&bitmap->write_lock);
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INIT_LIST_HEAD(&bitmap->complete_pages);
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init_waitqueue_head(&bitmap->write_wait);
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bitmap->write_pool = mempool_create_kmalloc_pool(WRITE_POOL_SIZE,
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sizeof(struct page_list));
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err = -ENOMEM;
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@ -1613,15 +1523,6 @@ int bitmap_create(mddev_t *mddev)
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mddev->bitmap = bitmap;
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if (file)
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/* kick off the bitmap writeback daemon */
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bitmap->writeback_daemon =
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bitmap_start_daemon(bitmap,
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bitmap_writeback_daemon,
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"bitmap_wb");
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if (IS_ERR(bitmap->writeback_daemon))
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return PTR_ERR(bitmap->writeback_daemon);
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mddev->thread->timeout = bitmap->daemon_sleep * HZ;
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return bitmap_update_sb(bitmap);
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@ -244,13 +244,7 @@ struct bitmap {
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unsigned long daemon_lastrun; /* jiffies of last run */
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unsigned long daemon_sleep; /* how many seconds between updates? */
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/*
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* bitmap_writeback_daemon waits for file-pages that have been written,
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* as there is no way to get a call-back when a page write completes.
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*/
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mdk_thread_t *writeback_daemon;
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spinlock_t write_lock;
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wait_queue_head_t write_wait;
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struct list_head complete_pages;
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mempool_t *write_pool;
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};
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