intelfb: add vsync interrupt support
[safe/jmp/linux-2.6] / drivers / md / bitmap.c
index 09d32db..f8ffaee 100644 (file)
@@ -21,7 +21,6 @@
  */
 
 #include <linux/module.h>
-#include <linux/version.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
 #include <linux/init.h>
@@ -90,16 +89,6 @@ int bitmap_active(struct bitmap *bitmap)
 }
 
 #define WRITE_POOL_SIZE 256
-/* mempool for queueing pending writes on the bitmap file */
-static void *write_pool_alloc(unsigned int gfp_flags, void *data)
-{
-       return kmalloc(sizeof(struct page_list), gfp_flags);
-}
-
-static void write_pool_free(void *ptr, void *data)
-{
-       kfree(ptr);
-}
 
 /*
  * just a placeholder - calls kmalloc for bitmap pages
@@ -201,7 +190,7 @@ out:
 /* if page is completely empty, put it back on the free list, or dealloc it */
 /* if page was hijacked, unmark the flag so it might get alloced next time */
 /* Note: lock should be held when calling this */
-static inline void bitmap_checkfree(struct bitmap *bitmap, unsigned long page)
+static void bitmap_checkfree(struct bitmap *bitmap, unsigned long page)
 {
        char *ptr;
 
@@ -270,19 +259,21 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
 
        if (!page)
                return ERR_PTR(-ENOMEM);
-       do {
-               ITERATE_RDEV(mddev, rdev, tmp)
-                       if (rdev->in_sync && !rdev->faulty)
-                               goto found;
-               return ERR_PTR(-EIO);
 
-       found:
+       ITERATE_RDEV(mddev, rdev, tmp) {
+               if (! test_bit(In_sync, &rdev->flags)
+                   || test_bit(Faulty, &rdev->flags))
+                       continue;
+
                target = (rdev->sb_offset << 1) + offset + index * (PAGE_SIZE/512);
 
-       } while (!sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ));
+               if (sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ)) {
+                       page->index = index;
+                       return page;
+               }
+       }
+       return ERR_PTR(-EIO);
 
-       page->index = index;
-       return page;
 }
 
 static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wait)
@@ -291,7 +282,8 @@ static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wai
        struct list_head *tmp;
 
        ITERATE_RDEV(mddev, rdev, tmp)
-               if (rdev->in_sync && !rdev->faulty)
+               if (test_bit(In_sync, &rdev->flags)
+                   && !test_bit(Faulty, &rdev->flags))
                        md_super_write(mddev, rdev,
                                       (rdev->sb_offset<<1) + offset
                                       + page->index * (PAGE_SIZE/512),
@@ -299,7 +291,7 @@ static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wai
                                       page);
 
        if (wait)
-               wait_event(mddev->sb_wait, atomic_read(&mddev->pending_writes)==0);
+               md_super_wait(mddev);
        return 0;
 }
 
@@ -313,6 +305,8 @@ static int write_page(struct bitmap *bitmap, struct page *page, int wait)
        if (bitmap->file == NULL)
                return write_sb_page(bitmap->mddev, bitmap->offset, page, wait);
 
+       flush_dcache_page(page); /* make sure visible to anyone reading the file */
+
        if (wait)
                lock_page(page);
        else {
@@ -324,9 +318,9 @@ static int write_page(struct bitmap *bitmap, struct page *page, int wait)
                }
        }
 
-       ret = page->mapping->a_ops->prepare_write(NULL, page, 0, PAGE_SIZE);
+       ret = page->mapping->a_ops->prepare_write(bitmap->file, page, 0, PAGE_SIZE);
        if (!ret)
-               ret = page->mapping->a_ops->commit_write(NULL, page, 0,
+               ret = page->mapping->a_ops->commit_write(bitmap->file, page, 0,
                        PAGE_SIZE);
        if (ret) {
                unlock_page(page);
@@ -339,7 +333,7 @@ static int write_page(struct bitmap *bitmap, struct page *page, int 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);
+               get_page(page);
                spin_lock(&bitmap->write_lock);
                list_add(&item->list, &bitmap->complete_pages);
                spin_unlock(&bitmap->write_lock);
@@ -355,10 +349,10 @@ static struct page *read_page(struct file *file, unsigned long index,
        struct inode *inode = file->f_mapping->host;
        struct page *page = NULL;
        loff_t isize = i_size_read(inode);
-       unsigned long end_index = isize >> PAGE_CACHE_SHIFT;
+       unsigned long end_index = isize >> PAGE_SHIFT;
 
-       PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_CACHE_SIZE,
-                       (unsigned long long)index << PAGE_CACHE_SHIFT);
+       PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_SIZE,
+                       (unsigned long long)index << PAGE_SHIFT);
 
        page = read_cache_page(inode->i_mapping, index,
                        (filler_t *)inode->i_mapping->a_ops->readpage, file);
@@ -366,7 +360,7 @@ static struct page *read_page(struct file *file, unsigned long index,
                goto out;
        wait_on_page_locked(page);
        if (!PageUptodate(page) || PageError(page)) {
-               page_cache_release(page);
+               put_page(page);
                page = ERR_PTR(-EIO);
                goto out;
        }
@@ -374,14 +368,14 @@ static struct page *read_page(struct file *file, unsigned long index,
        if (index > end_index) /* we have read beyond EOF */
                *bytes_read = 0;
        else if (index == end_index) /* possible short read */
-               *bytes_read = isize & ~PAGE_CACHE_MASK;
+               *bytes_read = isize & ~PAGE_MASK;
        else
-               *bytes_read = PAGE_CACHE_SIZE; /* got a full page */
+               *bytes_read = PAGE_SIZE; /* got a full page */
 out:
        if (IS_ERR(page))
                printk(KERN_ALERT "md: bitmap read error: (%dB @ %Lu): %ld\n",
-                       (int)PAGE_CACHE_SIZE,
-                       (unsigned long long)index << PAGE_CACHE_SHIFT,
+                       (int)PAGE_SIZE,
+                       (unsigned long long)index << PAGE_SHIFT,
                        PTR_ERR(page));
        return page;
 }
@@ -404,11 +398,11 @@ int bitmap_update_sb(struct bitmap *bitmap)
                return 0;
        }
        spin_unlock_irqrestore(&bitmap->lock, flags);
-       sb = (bitmap_super_t *)kmap(bitmap->sb_page);
+       sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
        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);
+       kunmap_atomic(sb, KM_USER0);
        return write_page(bitmap, bitmap->sb_page, 1);
 }
 
@@ -419,7 +413,7 @@ void bitmap_print_sb(struct bitmap *bitmap)
 
        if (!bitmap || !bitmap->sb_page)
                return;
-       sb = (bitmap_super_t *)kmap(bitmap->sb_page);
+       sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
        printk(KERN_DEBUG "%s: bitmap file superblock:\n", bmname(bitmap));
        printk(KERN_DEBUG "         magic: %08x\n", le32_to_cpu(sb->magic));
        printk(KERN_DEBUG "       version: %d\n", le32_to_cpu(sb->version));
@@ -437,7 +431,8 @@ void bitmap_print_sb(struct bitmap *bitmap)
        printk(KERN_DEBUG "  daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));
        printk(KERN_DEBUG "     sync size: %llu KB\n",
                        (unsigned long long)le64_to_cpu(sb->sync_size)/2);
-       kunmap(bitmap->sb_page);
+       printk(KERN_DEBUG "max write behind: %d\n", le32_to_cpu(sb->write_behind));
+       kunmap_atomic(sb, KM_USER0);
 }
 
 /* read the superblock from the bitmap file and initialize some bitmap fields */
@@ -445,7 +440,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 {
        char *reason = NULL;
        bitmap_super_t *sb;
-       unsigned long chunksize, daemon_sleep;
+       unsigned long chunksize, daemon_sleep, write_behind;
        unsigned long bytes_read;
        unsigned long long events;
        int err = -EINVAL;
@@ -463,7 +458,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
                return err;
        }
 
-       sb = (bitmap_super_t *)kmap(bitmap->sb_page);
+       sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 
        if (bytes_read < sizeof(*sb)) { /* short read */
                printk(KERN_INFO "%s: bitmap file superblock truncated\n",
@@ -474,18 +469,22 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 
        chunksize = le32_to_cpu(sb->chunksize);
        daemon_sleep = le32_to_cpu(sb->daemon_sleep);
+       write_behind = le32_to_cpu(sb->write_behind);
 
        /* verify that the bitmap-specific fields are valid */
        if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
                reason = "bad magic";
-       else if (sb->version != cpu_to_le32(BITMAP_MAJOR))
+       else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
+                le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
                reason = "unrecognized superblock version";
-       else if (chunksize < 512 || chunksize > (1024 * 1024 * 4))
-               reason = "bitmap chunksize out of range (512B - 4MB)";
+       else if (chunksize < PAGE_SIZE)
+               reason = "bitmap chunksize too small";
        else if ((1 << ffz(~chunksize)) != chunksize)
                reason = "bitmap chunksize not a power of 2";
-       else if (daemon_sleep < 1 || daemon_sleep > 15)
+       else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT / HZ)
                reason = "daemon sleep period out of range";
+       else if (write_behind > COUNTER_MAX)
+               reason = "write-behind limit out of range (0 - 16383)";
        if (reason) {
                printk(KERN_INFO "%s: invalid bitmap file superblock: %s\n",
                        bmname(bitmap), reason);
@@ -518,11 +517,17 @@ success:
        /* assign fields using values from superblock */
        bitmap->chunksize = chunksize;
        bitmap->daemon_sleep = daemon_sleep;
+       bitmap->daemon_lastrun = jiffies;
+       bitmap->max_write_behind = write_behind;
        bitmap->flags |= sb->state;
+       if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
+               bitmap->flags |= BITMAP_HOSTENDIAN;
        bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
+       if (sb->state & BITMAP_STALE)
+               bitmap->events_cleared = bitmap->mddev->events;
        err = 0;
 out:
-       kunmap(bitmap->sb_page);
+       kunmap_atomic(sb, KM_USER0);
        if (err)
                bitmap_print_sb(bitmap);
        return err;
@@ -541,13 +546,13 @@ static void bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
        unsigned long flags;
 
        spin_lock_irqsave(&bitmap->lock, flags);
-       if (!bitmap || !bitmap->sb_page) { /* can't set the state */
+       if (!bitmap->sb_page) { /* can't set the state */
                spin_unlock_irqrestore(&bitmap->lock, flags);
                return;
        }
-       page_cache_get(bitmap->sb_page);
+       get_page(bitmap->sb_page);
        spin_unlock_irqrestore(&bitmap->lock, flags);
-       sb = (bitmap_super_t *)kmap(bitmap->sb_page);
+       sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
        switch (op) {
                case MASK_SET: sb->state |= bits;
                                break;
@@ -555,8 +560,8 @@ static void bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
                                break;
                default: BUG();
        }
-       kunmap(bitmap->sb_page);
-       page_cache_release(bitmap->sb_page);
+       kunmap_atomic(sb, KM_USER0);
+       put_page(bitmap->sb_page);
 }
 
 /*
@@ -609,15 +614,14 @@ static void bitmap_file_unmap(struct bitmap *bitmap)
 
        while (pages--)
                if (map[pages]->index != 0) /* 0 is sb_page, release it below */
-                       page_cache_release(map[pages]);
+                       put_page(map[pages]);
        kfree(map);
        kfree(attr);
 
-       if (sb_page)
-               page_cache_release(sb_page);
+       safe_put_page(sb_page);
 }
 
-static void bitmap_stop_daemons(struct bitmap *bitmap);
+static void bitmap_stop_daemon(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)
@@ -641,7 +645,7 @@ static void drain_write_queues(struct bitmap *bitmap)
 
        while ((item = dequeue_page(bitmap))) {
                /* don't bother to wait */
-               page_cache_release(item->page);
+               put_page(item->page);
                mempool_free(item, bitmap->write_pool);
        }
 
@@ -659,7 +663,7 @@ static void bitmap_file_put(struct bitmap *bitmap)
        bitmap->file = NULL;
        spin_unlock_irqrestore(&bitmap->lock, flags);
 
-       bitmap_stop_daemons(bitmap);
+       bitmap_stop_daemon(bitmap);
 
        drain_write_queues(bitmap);
 
@@ -750,11 +754,14 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
 
        /* make sure the page stays cached until it gets written out */
        if (! (get_page_attr(bitmap, page) & BITMAP_PAGE_DIRTY))
-               page_cache_get(page);
+               get_page(page);
 
        /* set the bit */
        kaddr = kmap_atomic(page, KM_USER0);
-       set_bit(bit, kaddr);
+       if (bitmap->flags & BITMAP_HOSTENDIAN)
+               set_bit(bit, kaddr);
+       else
+               ext2_set_bit(bit, kaddr);
        kunmap_atomic(kaddr, KM_USER0);
        PRINTK("set file bit %lu page %lu\n", bit, page->index);
 
@@ -812,13 +819,12 @@ int bitmap_unplug(struct bitmap *bitmap)
                                            wake_up_process(bitmap->writeback_daemon->tsk));
                        spin_unlock_irq(&bitmap->write_lock);
                } else
-                       wait_event(bitmap->mddev->sb_wait,
-                                  atomic_read(&bitmap->mddev->pending_writes)==0);
+                       md_super_wait(bitmap->mddev);
        }
        return 0;
 }
 
-static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset);
+static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
 /* * bitmap_init_from_disk -- called at bitmap_create time to initialize
  * the in-memory bitmap from the on-disk bitmap -- also, sets up the
  * memory mapping of the bitmap file
@@ -826,8 +832,11 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset);
  *   if there's no bitmap file, or if the bitmap file had been
  *   previously kicked from the array, we mark all the bits as
  *   1's in order to cause a full resync.
+ *
+ * We ignore all bits for sectors that end earlier than 'start'.
+ * This is used when reading an out-of-date bitmap...
  */
-static int bitmap_init_from_disk(struct bitmap *bitmap)
+static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 {
        unsigned long i, chunks, index, oldindex, bit;
        struct page *page = NULL, *oldpage = NULL;
@@ -836,6 +845,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap)
        unsigned long bytes, offset, dummy;
        int outofdate;
        int ret = -ENOSPC;
+       void *paddr;
 
        chunks = bitmap->chunks;
        file = bitmap->file;
@@ -869,21 +879,18 @@ static int bitmap_init_from_disk(struct bitmap *bitmap)
        if (!bitmap->filemap)
                goto out;
 
-       bitmap->filemap_attr = kmalloc(sizeof(long) * num_pages, GFP_KERNEL);
+       bitmap->filemap_attr = kzalloc(sizeof(long) * num_pages, GFP_KERNEL);
        if (!bitmap->filemap_attr)
                goto out;
 
-       memset(bitmap->filemap_attr, 0, sizeof(long) * num_pages);
-
        oldindex = ~0L;
 
        for (i = 0; i < chunks; i++) {
+               int b;
                index = file_page_index(i);
                bit = file_page_offset(i);
                if (index != oldindex) { /* this is a new page, read it in */
                        /* unmap the old page, we're done with it */
-                       if (oldpage != NULL)
-                               kunmap(oldpage);
                        if (index == 0) {
                                /*
                                 * if we're here then the superblock page
@@ -906,30 +913,39 @@ static int bitmap_init_from_disk(struct bitmap *bitmap)
 
                        oldindex = index;
                        oldpage = page;
-                       kmap(page);
 
                        if (outofdate) {
                                /*
                                 * if bitmap is out of date, dirty the
                                 * whole page and write it out
                                 */
-                               memset(page_address(page) + offset, 0xff,
-                                       PAGE_SIZE - offset);
+                               paddr = kmap_atomic(page, KM_USER0);
+                               memset(paddr + offset, 0xff,
+                                      PAGE_SIZE - offset);
+                               kunmap_atomic(paddr, KM_USER0);
                                ret = write_page(bitmap, page, 1);
                                if (ret) {
-                                       kunmap(page);
                                        /* release, page not in filemap yet */
-                                       page_cache_release(page);
+                                       put_page(page);
                                        goto out;
                                }
                        }
 
                        bitmap->filemap[bitmap->file_pages++] = page;
                }
-               if (test_bit(bit, page_address(page))) {
+               paddr = kmap_atomic(page, KM_USER0);
+               if (bitmap->flags & BITMAP_HOSTENDIAN)
+                       b = test_bit(bit, paddr);
+               else
+                       b = ext2_test_bit(bit, paddr);
+               kunmap_atomic(paddr, KM_USER0);
+               if (b) {
                        /* if the disk bit is set, set the memory bit */
-                       bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap));
+                       bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap),
+                                              ((i+1) << (CHUNK_BLOCK_SHIFT(bitmap)) >= start)
+                               );
                        bit_cnt++;
+                       set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
                }
        }
 
@@ -937,9 +953,6 @@ static int bitmap_init_from_disk(struct bitmap *bitmap)
        ret = 0;
        bitmap_mask_state(bitmap, BITMAP_STALE, MASK_UNSET);
 
-       if (page) /* unmap the last page */
-               kunmap(page);
-
        if (bit_cnt) { /* Kick recovery if any bits were set */
                set_bit(MD_RECOVERY_NEEDED, &bitmap->mddev->recovery);
                md_wakeup_thread(bitmap->mddev->thread);
@@ -995,6 +1008,7 @@ int bitmap_daemon_work(struct bitmap *bitmap)
        int err = 0;
        int blocks;
        int attr;
+       void *paddr;
 
        if (bitmap == NULL)
                return 0;
@@ -1017,7 +1031,7 @@ int bitmap_daemon_work(struct bitmap *bitmap)
                        /* skip this page unless it's marked as needing cleaning */
                        if (!((attr=get_page_attr(bitmap, page)) & BITMAP_PAGE_CLEAN)) {
                                if (attr & BITMAP_PAGE_NEEDWRITE) {
-                                       page_cache_get(page);
+                                       get_page(page);
                                        clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
                                }
                                spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -1031,13 +1045,13 @@ int bitmap_daemon_work(struct bitmap *bitmap)
                                        default:
                                                bitmap_file_kick(bitmap);
                                        }
-                                       page_cache_release(page);
+                                       put_page(page);
                                }
                                continue;
                        }
 
                        /* grab the new page, sync and release the old */
-                       page_cache_get(page);
+                       get_page(page);
                        if (lastpage != NULL) {
                                if (get_page_attr(bitmap, lastpage) & BITMAP_PAGE_NEEDWRITE) {
                                        clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
@@ -1051,14 +1065,12 @@ int bitmap_daemon_work(struct bitmap *bitmap)
                                        set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
                                        spin_unlock_irqrestore(&bitmap->lock, flags);
                                }
-                               kunmap(lastpage);
-                               page_cache_release(lastpage);
+                               put_page(lastpage);
                                if (err)
                                        bitmap_file_kick(bitmap);
                        } else
                                spin_unlock_irqrestore(&bitmap->lock, flags);
                        lastpage = page;
-                       kmap(page);
 /*
                        printk("bitmap clean at page %lu\n", j);
 */
@@ -1081,7 +1093,12 @@ int bitmap_daemon_work(struct bitmap *bitmap)
                                                  -1);
 
                                /* clear the bit */
-                               clear_bit(file_page_offset(j), page_address(page));
+                               paddr = kmap_atomic(page, KM_USER0);
+                               if (bitmap->flags & BITMAP_HOSTENDIAN)
+                                       clear_bit(file_page_offset(j), paddr);
+                               else
+                                       ext2_clear_bit(file_page_offset(j), paddr);
+                               kunmap_atomic(paddr, KM_USER0);
                        }
                }
                spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -1089,7 +1106,6 @@ int bitmap_daemon_work(struct bitmap *bitmap)
 
        /* now sync the final page */
        if (lastpage != NULL) {
-               kunmap(lastpage);
                spin_lock_irqsave(&bitmap->lock, flags);
                if (get_page_attr(bitmap, lastpage) &BITMAP_PAGE_NEEDWRITE) {
                        clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
@@ -1104,7 +1120,7 @@ int bitmap_daemon_work(struct bitmap *bitmap)
                        spin_unlock_irqrestore(&bitmap->lock, flags);
                }
 
-               page_cache_release(lastpage);
+               put_page(lastpage);
        }
 
        return err;
@@ -1141,6 +1157,9 @@ static void bitmap_writeback_daemon(mddev_t *mddev)
                err = -EINTR;
                goto out;
        }
+       if (bitmap == NULL)
+               /* about to be stopped. */
+               return;
 
        PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap));
        /* wait on bitmap page writebacks */
@@ -1152,7 +1171,7 @@ static void bitmap_writeback_daemon(mddev_t *mddev)
                PRINTK("finished page writeback: %p\n", page);
 
                err = PageError(page);
-               page_cache_release(page);
+               put_page(page);
                if (err) {
                        printk(KERN_WARNING "%s: bitmap file writeback "
                               "failed (page %lu): %d\n",
@@ -1170,21 +1189,12 @@ static void bitmap_writeback_daemon(mddev_t *mddev)
        }
 }
 
-static int bitmap_start_daemon(struct bitmap *bitmap, mdk_thread_t **ptr,
+static mdk_thread_t *bitmap_start_daemon(struct bitmap *bitmap,
                                void (*func)(mddev_t *), char *name)
 {
        mdk_thread_t *daemon;
-       unsigned long flags;
        char namebuf[32];
 
-       spin_lock_irqsave(&bitmap->lock, flags);
-       *ptr = NULL;
-
-       if (!bitmap->file) /* no need for daemon if there's no backing file */
-               goto out_unlock;
-
-       spin_unlock_irqrestore(&bitmap->lock, flags);
-
 #ifdef INJECT_FATAL_FAULT_2
        daemon = NULL;
 #else
@@ -1194,47 +1204,32 @@ static int bitmap_start_daemon(struct bitmap *bitmap, mdk_thread_t **ptr,
        if (!daemon) {
                printk(KERN_ERR "%s: failed to start bitmap daemon\n",
                        bmname(bitmap));
-               return -ECHILD;
+               return ERR_PTR(-ECHILD);
        }
 
-       spin_lock_irqsave(&bitmap->lock, flags);
-       *ptr = daemon;
-
        md_wakeup_thread(daemon); /* start it running */
 
        PRINTK("%s: %s daemon (pid %d) started...\n",
                bmname(bitmap), name, daemon->tsk->pid);
-out_unlock:
-       spin_unlock_irqrestore(&bitmap->lock, flags);
-       return 0;
-}
 
-static int bitmap_start_daemons(struct bitmap *bitmap)
-{
-       int err = bitmap_start_daemon(bitmap, &bitmap->writeback_daemon,
-                                       bitmap_writeback_daemon, "bitmap_wb");
-       return err;
+       return daemon;
 }
 
-static void bitmap_stop_daemon(struct bitmap *bitmap, mdk_thread_t **ptr)
+static void bitmap_stop_daemon(struct bitmap *bitmap)
 {
-       mdk_thread_t *daemon;
-       unsigned long flags;
-
-       spin_lock_irqsave(&bitmap->lock, flags);
-       daemon = *ptr;
-       *ptr = NULL;
-       spin_unlock_irqrestore(&bitmap->lock, flags);
-       if (daemon)
-               md_unregister_thread(daemon); /* destroy the thread */
-}
+       /* the daemon can't stop itself... it'll just exit instead... */
+       if (bitmap->writeback_daemon && ! IS_ERR(bitmap->writeback_daemon) &&
+           current->pid != bitmap->writeback_daemon->tsk->pid) {
+               mdk_thread_t *daemon;
+               unsigned long flags;
 
-static void bitmap_stop_daemons(struct bitmap *bitmap)
-{
-       /* the daemons can't stop themselves... they'll just exit instead... */
-       if (bitmap->writeback_daemon &&
-           current->pid != bitmap->writeback_daemon->tsk->pid)
-               bitmap_stop_daemon(bitmap, &bitmap->writeback_daemon);
+               spin_lock_irqsave(&bitmap->lock, flags);
+               daemon = bitmap->writeback_daemon;
+               bitmap->writeback_daemon = NULL;
+               spin_unlock_irqrestore(&bitmap->lock, flags);
+               if (daemon && ! IS_ERR(daemon))
+                       md_unregister_thread(daemon); /* destroy the thread */
+       }
 }
 
 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
@@ -1274,9 +1269,16 @@ static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
        }
 }
 
-int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors)
+int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
 {
        if (!bitmap) return 0;
+
+       if (behind) {
+               atomic_inc(&bitmap->behind_writes);
+               PRINTK(KERN_DEBUG "inc write-behind count %d/%d\n",
+                 atomic_read(&bitmap->behind_writes), bitmap->max_write_behind);
+       }
+
        while (sectors) {
                int blocks;
                bitmap_counter_t *bmc;
@@ -1297,7 +1299,7 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect
                case 1:
                        *bmc = 2;
                }
-               if ((*bmc & COUNTER_MAX) == COUNTER_MAX) BUG();
+               BUG_ON((*bmc & COUNTER_MAX) == COUNTER_MAX);
                (*bmc)++;
 
                spin_unlock_irq(&bitmap->lock);
@@ -1311,9 +1313,15 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect
 }
 
 void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
-                    int success)
+                    int success, int behind)
 {
        if (!bitmap) return;
+       if (behind) {
+               atomic_dec(&bitmap->behind_writes);
+               PRINTK(KERN_DEBUG "dec write-behind count %d/%d\n",
+                 atomic_read(&bitmap->behind_writes), bitmap->max_write_behind);
+       }
+
        while (sectors) {
                int blocks;
                unsigned long flags;
@@ -1424,7 +1432,7 @@ void bitmap_close_sync(struct bitmap *bitmap)
        }
 }
 
-static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset)
+static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed)
 {
        /* For each chunk covered by any of these sectors, set the
         * counter to 1 and set resync_needed.  They should all
@@ -1441,7 +1449,7 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset)
        }
        if (! *bmc) {
                struct page *page;
-               *bmc = 1 | NEEDED_MASK;
+               *bmc = 1 | (needed?NEEDED_MASK:0);
                bitmap_count_page(bitmap, offset, 1);
                page = filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap));
                set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
@@ -1451,19 +1459,39 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset)
 }
 
 /*
+ * flush out any pending updates
+ */
+void bitmap_flush(mddev_t *mddev)
+{
+       struct bitmap *bitmap = mddev->bitmap;
+       int sleep;
+
+       if (!bitmap) /* there was no bitmap */
+               return;
+
+       /* run the daemon_work three time to ensure everything is flushed
+        * that can be
+        */
+       sleep = bitmap->daemon_sleep;
+       bitmap->daemon_sleep = 0;
+       bitmap_daemon_work(bitmap);
+       bitmap_daemon_work(bitmap);
+       bitmap_daemon_work(bitmap);
+       bitmap->daemon_sleep = sleep;
+       bitmap_update_sb(bitmap);
+}
+
+/*
  * free memory that was allocated
  */
-void bitmap_destroy(mddev_t *mddev)
+static void bitmap_free(struct bitmap *bitmap)
 {
        unsigned long k, pages;
        struct bitmap_page *bp;
-       struct bitmap *bitmap = mddev->bitmap;
 
        if (!bitmap) /* there was no bitmap */
                return;
 
-       mddev->bitmap = NULL; /* disconnect from the md device */
-
        /* release the bitmap file and kill the daemon */
        bitmap_file_put(bitmap);
 
@@ -1481,6 +1509,19 @@ void bitmap_destroy(mddev_t *mddev)
        kfree(bp);
        kfree(bitmap);
 }
+void bitmap_destroy(mddev_t *mddev)
+{
+       struct bitmap *bitmap = mddev->bitmap;
+
+       if (!bitmap) /* there was no bitmap */
+               return;
+
+       mddev->bitmap = NULL; /* disconnect from the md device */
+       if (mddev->thread)
+               mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
+
+       bitmap_free(bitmap);
+}
 
 /*
  * initialize the bitmap structure
@@ -1494,6 +1535,7 @@ int bitmap_create(mddev_t *mddev)
        unsigned long pages;
        struct file *file = mddev->bitmap_file;
        int err;
+       sector_t start;
 
        BUG_ON(sizeof(bitmap_super_t) != 256);
 
@@ -1502,23 +1544,21 @@ int bitmap_create(mddev_t *mddev)
 
        BUG_ON(file && mddev->bitmap_offset);
 
-       bitmap = kmalloc(sizeof(*bitmap), GFP_KERNEL);
+       bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
        if (!bitmap)
                return -ENOMEM;
 
-       memset(bitmap, 0, sizeof(*bitmap));
-
        spin_lock_init(&bitmap->lock);
        bitmap->mddev = mddev;
-       mddev->bitmap = bitmap;
 
        spin_lock_init(&bitmap->write_lock);
        INIT_LIST_HEAD(&bitmap->complete_pages);
        init_waitqueue_head(&bitmap->write_wait);
-       bitmap->write_pool = mempool_create(WRITE_POOL_SIZE, write_pool_alloc,
-                               write_pool_free, NULL);
+       bitmap->write_pool = mempool_create_kmalloc_pool(WRITE_POOL_SIZE,
+                                               sizeof(struct page_list));
+       err = -ENOMEM;
        if (!bitmap->write_pool)
-               return -ENOMEM;
+               goto error;
 
        bitmap->file = file;
        bitmap->offset = mddev->bitmap_offset;
@@ -1526,7 +1566,7 @@ int bitmap_create(mddev_t *mddev)
        /* read superblock from bitmap file (this sets bitmap->chunksize) */
        err = bitmap_read_sb(bitmap);
        if (err)
-               return err;
+               goto error;
 
        bitmap->chunkshift = find_first_bit(&bitmap->chunksize,
                                        sizeof(bitmap->chunksize));
@@ -1548,29 +1588,47 @@ int bitmap_create(mddev_t *mddev)
 #ifdef INJECT_FATAL_FAULT_1
        bitmap->bp = NULL;
 #else
-       bitmap->bp = kmalloc(pages * sizeof(*bitmap->bp), GFP_KERNEL);
+       bitmap->bp = kzalloc(pages * sizeof(*bitmap->bp), GFP_KERNEL);
 #endif
+       err = -ENOMEM;
        if (!bitmap->bp)
-               return -ENOMEM;
-       memset(bitmap->bp, 0, pages * sizeof(*bitmap->bp));
+               goto error;
 
        bitmap->flags |= BITMAP_ACTIVE;
 
        /* now that we have some pages available, initialize the in-memory
         * bitmap from the on-disk bitmap */
-       err = bitmap_init_from_disk(bitmap);
+       start = 0;
+       if (mddev->degraded == 0
+           || bitmap->events_cleared == mddev->events)
+               /* no need to keep dirty bits to optimise a re-add of a missing device */
+               start = mddev->recovery_cp;
+       err = bitmap_init_from_disk(bitmap, start);
 
        if (err)
-               return err;
+               goto error;
 
        printk(KERN_INFO "created bitmap (%lu pages) for device %s\n",
                pages, bmname(bitmap));
 
-       /* kick off the bitmap daemons */
-       err = bitmap_start_daemons(bitmap);
-       if (err)
-               return err;
+       mddev->bitmap = bitmap;
+
+       if (file)
+               /* kick off the bitmap writeback daemon */
+               bitmap->writeback_daemon =
+                       bitmap_start_daemon(bitmap,
+                                           bitmap_writeback_daemon,
+                                           "bitmap_wb");
+
+       if (IS_ERR(bitmap->writeback_daemon))
+               return PTR_ERR(bitmap->writeback_daemon);
+       mddev->thread->timeout = bitmap->daemon_sleep * HZ;
+
        return bitmap_update_sb(bitmap);
+
+ error:
+       bitmap_free(bitmap);
+       return err;
 }
 
 /* the bitmap API -- for raid personalities */