6 files changed, 1970 insertions, 15 deletions

diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 90de9c146a5f..d3efedf6a6ad 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -7,6 +7,7 @@ dm-mod-objs	:= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
 dm-multipath-objs := dm-hw-handler.o dm-path-selector.o dm-mpath.o
 dm-snapshot-objs := dm-snap.o dm-exception-store.o
 dm-mirror-objs  := dm-log.o dm-raid1.o
+md-mod-objs     := md.o bitmap.o
 raid6-objs      := raid6main.o raid6algos.o raid6recov.o raid6tables.o \
                    raid6int1.o raid6int2.o raid6int4.o \
                    raid6int8.o raid6int16.o raid6int32.o \
@@ -28,7 +29,7 @@ obj-$(CONFIG_MD_RAID5)		+= raid5.o xor.o
 obj-$(CONFIG_MD_RAID6)          += raid6.o xor.o
 obj-$(CONFIG_MD_MULTIPATH)      += multipath.o
 obj-$(CONFIG_MD_FAULTY)         += faulty.o
-obj-$(CONFIG_BLK_DEV_MD)        += md.o
+obj-$(CONFIG_BLK_DEV_MD)        += md-mod.o
 obj-$(CONFIG_BLK_DEV_DM)        += dm-mod.o
 obj-$(CONFIG_DM_CRYPT)          += dm-crypt.o
 obj-$(CONFIG_DM_MULTIPATH)      += dm-multipath.o dm-round-robin.o
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
new file mode 100644
index 000000000000..34ffc133db05
--- /dev/null
+++ b/drivers/md/bitmap.c
@@ -0,0 +1,1519 @@
+/*
+ * bitmap.c two-level bitmap (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
+ *
+ * bitmap_create  - sets up the bitmap structure
+ * bitmap_destroy - destroys the bitmap structure
+ *
+ * additions, Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.:
+ * - added disk storage for bitmap
+ * - changes to allow various bitmap chunk sizes
+ * - added bitmap daemon (to asynchronously clear bitmap bits from disk)
+ */
+
+/*
+ * Still to do:
+ *
+ * flush after percent set rather than just time based. (maybe both).
+ * wait if count gets too high, wake when it drops to half.
+ * allow bitmap to be mirrored with superblock (before or after...)
+ * allow hot-add to re-instate a current device.
+ * allow hot-add of bitmap after quiessing device
+ */
+
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/config.h>
+#include <linux/timer.h>
+#include <linux/sched.h>
+#include <linux/list.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/buffer_head.h>
+#include <linux/raid/md.h>
+#include <linux/raid/bitmap.h>
+
+/* debug macros */
+
+#define DEBUG 0
+
+#if DEBUG
+/* these are for debugging purposes only! */
+
+/* define one and only one of these */
+#define INJECT_FAULTS_1 0 /* cause bitmap_alloc_page to fail always */
+#define INJECT_FAULTS_2 0 /* cause bitmap file to be kicked when first bit set*/
+#define INJECT_FAULTS_3 0 /* treat bitmap file as kicked at init time */
+#define INJECT_FAULTS_4 0 /* undef */
+#define INJECT_FAULTS_5 0 /* undef */
+#define INJECT_FAULTS_6 0
+
+/* if these are defined, the driver will fail! debug only */
+#define INJECT_FATAL_FAULT_1 0 /* fail kmalloc, causing bitmap_create to fail */
+#define INJECT_FATAL_FAULT_2 0 /* undef */
+#define INJECT_FATAL_FAULT_3 0 /* undef */
+#endif
+
+//#define DPRINTK PRINTK /* set this NULL to avoid verbose debug output */
+#define DPRINTK(x...) do { } while(0)
+
+#ifndef PRINTK
+#  if DEBUG > 0
+#    define PRINTK(x...) printk(KERN_DEBUG x)
+#  else
+#    define PRINTK(x...)
+#  endif
+#endif
+
+static inline char * bmname(struct bitmap *bitmap)
+{
+        return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
+}
+
+
+/*
+ * test if the bitmap is active
+ */
+int bitmap_active(struct bitmap *bitmap)
+{
+        unsigned long flags;
+        int res = 0;
+
+        if (!bitmap)
+                return res;
+        spin_lock_irqsave(&bitmap->lock, flags);
+        res = bitmap->flags & BITMAP_ACTIVE;
+        spin_unlock_irqrestore(&bitmap->lock, flags);
+        return res;
+}
+
+#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
+ */
+static unsigned char *bitmap_alloc_page(struct bitmap *bitmap)
+{
+        unsigned char *page;
+
+#if INJECT_FAULTS_1
+        page = NULL;
+#else
+        page = kmalloc(PAGE_SIZE, GFP_NOIO);
+#endif
+        if (!page)
+                printk("%s: bitmap_alloc_page FAILED\n", bmname(bitmap));
+        else
+                printk("%s: bitmap_alloc_page: allocated page at %p\n",
+                        bmname(bitmap), page);
+        return page;
+}
+
+/*
+ * for now just a placeholder -- just calls kfree for bitmap pages
+ */
+static void bitmap_free_page(struct bitmap *bitmap, unsigned char *page)
+{
+        PRINTK("%s: bitmap_free_page: free page %p\n", bmname(bitmap), page);
+        kfree(page);
+}
+
+/*
+ * check a page and, if necessary, allocate it (or hijack it if the alloc fails)
+ *
+ * 1) check to see if this page is allocated, if it's not then try to alloc
+ * 2) if the alloc fails, set the page's hijacked flag so we'll use the
+ *    page pointer directly as a counter
+ *
+ * if we find our page, we increment the page's refcount so that it stays
+ * allocated while we're using it
+ */
+static int bitmap_checkpage(struct bitmap *bitmap, unsigned long page, int create)
+{
+        unsigned char *mappage;
+
+        if (page >= bitmap->pages) {
+                printk(KERN_ALERT
+                        "%s: invalid bitmap page request: %lu (> %lu)\n",
+                        bmname(bitmap), page, bitmap->pages-1);
+                return -EINVAL;
+        }
+
+
+        if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
+                return 0;
+
+        if (bitmap->bp[page].map) /* page is already allocated, just return */
+                return 0;
+
+        if (!create)
+                return -ENOENT;
+
+        spin_unlock_irq(&bitmap->lock);
+
+        /* this page has not been allocated yet */
+
+        if ((mappage = bitmap_alloc_page(bitmap)) == NULL) {
+                PRINTK("%s: bitmap map page allocation failed, hijacking\n",
+                        bmname(bitmap));
+                /* failed - set the hijacked flag so that we can use the
+                 * pointer as a counter */
+                spin_lock_irq(&bitmap->lock);
+                if (!bitmap->bp[page].map)
+                        bitmap->bp[page].hijacked = 1;
+                goto out;
+        }
+
+        /* got a page */
+
+        spin_lock_irq(&bitmap->lock);
+
+        /* recheck the page */
+
+        if (bitmap->bp[page].map || bitmap->bp[page].hijacked) {
+                /* somebody beat us to getting the page */
+                bitmap_free_page(bitmap, mappage);
+                return 0;
+        }
+
+        /* no page was in place and we have one, so install it */
+
+        memset(mappage, 0, PAGE_SIZE);
+        bitmap->bp[page].map = mappage;
+        bitmap->missing_pages--;
+out:
+        return 0;
+}
+
+
+/* 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)
+{
+        char *ptr;
+
+        if (bitmap->bp[page].count) /* page is still busy */
+                return;
+
+        /* page is no longer in use, it can be released */
+
+        if (bitmap->bp[page].hijacked) { /* page was hijacked, undo this now */
+                bitmap->bp[page].hijacked = 0;
+                bitmap->bp[page].map = NULL;
+                return;
+        }
+
+        /* normal case, free the page */
+
+#if 0
+/* actually ... let's not.  We will probably need the page again exactly when
+ * memory is tight and we are flusing to disk
+ */
+        return;
+#else
+        ptr = bitmap->bp[page].map;
+        bitmap->bp[page].map = NULL;
+        bitmap->missing_pages++;
+        bitmap_free_page(bitmap, ptr);
+        return;
+#endif
+}
+
+
+/*
+ * bitmap file handling - read and write the bitmap file and its superblock
+ */
+
+/* copy the pathname of a file to a buffer */
+char *file_path(struct file *file, char *buf, int count)
+{
+        struct dentry *d;
+        struct vfsmount *v;
+
+        if (!buf)
+                return NULL;
+
+        d = file->f_dentry;
+        v = file->f_vfsmnt;
+
+        buf = d_path(d, v, buf, count);
+
+        return IS_ERR(buf) ? NULL : buf;
+}
+
+/*
+ * basic page I/O operations
+ */
+
+/*
+ * write out a page
+ */
+static int write_page(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 */
+        return write_one_page(page, wait);
+}
+
+/* read a page from a file, pinning it into cache, and return bytes_read */
+static struct page *read_page(struct file *file, unsigned long index,
+                                        unsigned long *bytes_read)
+{
+        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;
+
+        PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_CACHE_SIZE,
+                        (unsigned long long)index << PAGE_CACHE_SHIFT);
+
+        page = read_cache_page(inode->i_mapping, index,
+                        (filler_t *)inode->i_mapping->a_ops->readpage, file);
+        if (IS_ERR(page))
+                goto out;
+        wait_on_page_locked(page);
+        if (!PageUptodate(page) || PageError(page)) {
+                page_cache_release(page);
+                page = ERR_PTR(-EIO);
+                goto out;
+        }
+
+        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;
+        else
+                *bytes_read = PAGE_CACHE_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,
+                        PTR_ERR(page));
+        return page;
+}
+
+/*
+ * bitmap file superblock operations
+ */
+
+/* update the event counter and sync the superblock to disk */
+int bitmap_update_sb(struct bitmap *bitmap)
+{
+        bitmap_super_t *sb;
+        unsigned long flags;
+
+        if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
+                return 0;
+        spin_lock_irqsave(&bitmap->lock, flags);
+        if (!bitmap->sb_page) { /* no superblock */
+                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);
+        write_page(bitmap->sb_page, 0);
+        return 0;
+}
+
+/* print out the bitmap file superblock */
+void bitmap_print_sb(struct bitmap *bitmap)
+{
+        bitmap_super_t *sb;
+
+        if (!bitmap || !bitmap->sb_page)
+                return;
+        sb = (bitmap_super_t *)kmap(bitmap->sb_page);
+        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));
+        printk(KERN_DEBUG "        uuid: %08x.%08x.%08x.%08x\n",
+                                        *(__u32 *)(sb->uuid+0),
+                                        *(__u32 *)(sb->uuid+4),
+                                        *(__u32 *)(sb->uuid+8),
+                                        *(__u32 *)(sb->uuid+12));
+        printk(KERN_DEBUG "      events: %llu\n",
+                        (unsigned long long) le64_to_cpu(sb->events));
+        printk(KERN_DEBUG "events_clred: %llu\n",
+                        (unsigned long long) le64_to_cpu(sb->events_cleared));
+        printk(KERN_DEBUG "       state: %08x\n", le32_to_cpu(sb->state));
+        printk(KERN_DEBUG "   chunksize: %d B\n", le32_to_cpu(sb->chunksize));
+        printk(KERN_DEBUG "daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));
+        printk(KERN_DEBUG "   sync size: %llu KB\n", le64_to_cpu(sb->sync_size));
+        kunmap(bitmap->sb_page);
+}
+
+/* read the superblock from the bitmap file and initialize some bitmap fields */
+static int bitmap_read_sb(struct bitmap *bitmap)
+{
+        char *reason = NULL;
+        bitmap_super_t *sb;
+        unsigned long chunksize, daemon_sleep;
+        unsigned long bytes_read;
+        unsigned long long events;
+        int err = -EINVAL;
+
+        /* page 0 is the superblock, read it... */
+        bitmap->sb_page = read_page(bitmap->file, 0, &bytes_read);
+        if (IS_ERR(bitmap->sb_page)) {
+                err = PTR_ERR(bitmap->sb_page);
+                bitmap->sb_page = NULL;
+                return err;
+        }
+
+        sb = (bitmap_super_t *)kmap(bitmap->sb_page);
+
+        if (bytes_read < sizeof(*sb)) { /* short read */
+                printk(KERN_INFO "%s: bitmap file superblock truncated\n",
+                        bmname(bitmap));
+                err = -ENOSPC;
+                goto out;
+        }
+
+        chunksize = le32_to_cpu(sb->chunksize);
+        daemon_sleep = le32_to_cpu(sb->daemon_sleep);
+
+        /* 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))
+                reason = "unrecognized superblock version";
+        else if (chunksize < 512 || chunksize > (1024 * 1024 * 4))
+                reason = "bitmap chunksize out of range (512B - 4MB)";
+        else if ((1 << ffz(~chunksize)) != chunksize)
+                reason = "bitmap chunksize not a power of 2";
+        else if (daemon_sleep < 1 || daemon_sleep > 15)
+                reason = "daemon sleep period out of range";
+        if (reason) {
+                printk(KERN_INFO "%s: invalid bitmap file superblock: %s\n",
+                        bmname(bitmap), reason);
+                goto out;
+        }
+
+        /* keep the array size field of the bitmap superblock up to date */
+        sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
+
+        if (!bitmap->mddev->persistent)
+                goto success;
+
+        /*
+         * if we have a persistent array superblock, compare the
+         * bitmap's UUID and event counter to the mddev's
+         */
+        if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
+                printk(KERN_INFO "%s: bitmap superblock UUID mismatch\n",
+                        bmname(bitmap));
+                goto out;
+        }
+        events = le64_to_cpu(sb->events);
+        if (events < bitmap->mddev->events) {
+                printk(KERN_INFO "%s: bitmap file is out of date (%llu < %llu) "
+                        "-- forcing full recovery\n", bmname(bitmap), events,
+                        (unsigned long long) bitmap->mddev->events);
+                sb->state |= BITMAP_STALE;
+        }
+success:
+        /* assign fields using values from superblock */
+        bitmap->chunksize = chunksize;
+        bitmap->daemon_sleep = daemon_sleep;
+        bitmap->flags |= sb->state;
+        bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
+        err = 0;
+out:
+        kunmap(bitmap->sb_page);
+        if (err)
+                bitmap_print_sb(bitmap);
+        return err;
+}
+
+enum bitmap_mask_op {
+        MASK_SET,
+        MASK_UNSET
+};
+
+/* record the state of the bitmap in the superblock */
+static void bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
+                                enum bitmap_mask_op op)
+{
+        bitmap_super_t *sb;
+        unsigned long flags;
+
+        spin_lock_irqsave(&bitmap->lock, flags);
+        if (!bitmap || !bitmap->sb_page) { /* can't set the state */
+                spin_unlock_irqrestore(&bitmap->lock, flags);
+                return;
+        }
+        page_cache_get(bitmap->sb_page);
+        spin_unlock_irqrestore(&bitmap->lock, flags);
+        sb = (bitmap_super_t *)kmap(bitmap->sb_page);
+        switch (op) {
+                case MASK_SET: sb->state |= bits;
+                                break;
+                case MASK_UNSET: sb->state &= ~bits;
+                                break;
+                default: BUG();
+        }
+        kunmap(bitmap->sb_page);
+        page_cache_release(bitmap->sb_page);
+}
+
+/*
+ * general bitmap file operations
+ */
+
+/* calculate the index of the page that contains this bit */
+static inline unsigned long file_page_index(unsigned long chunk)
+{
+        return CHUNK_BIT_OFFSET(chunk) >> PAGE_BIT_SHIFT;
+}
+
+/* calculate the (bit) offset of this bit within a page */
+static inline unsigned long file_page_offset(unsigned long chunk)
+{
+        return CHUNK_BIT_OFFSET(chunk) & (PAGE_BITS - 1);
+}
+
+/*
+ * return a pointer to the page in the filemap that contains the given bit
+ *
+ * this lookup is complicated by the fact that the bitmap sb might be exactly
+ * 1 page (e.g., x86) or less than 1 page -- so the bitmap might start on page
+ * 0 or page 1
+ */
+static inline struct page *filemap_get_page(struct bitmap *bitmap,
+                                        unsigned long chunk)
+{
+        return bitmap->filemap[file_page_index(chunk) - file_page_index(0)];
+}
+
+
+static void bitmap_file_unmap(struct bitmap *bitmap)
+{
+        struct page **map, *sb_page;
+        unsigned long *attr;
+        int pages;
+        unsigned long flags;
+
+        spin_lock_irqsave(&bitmap->lock, flags);
+        map = bitmap->filemap;
+        bitmap->filemap = NULL;
+        attr = bitmap->filemap_attr;
+        bitmap->filemap_attr = NULL;
+        pages = bitmap->file_pages;
+        bitmap->file_pages = 0;
+        sb_page = bitmap->sb_page;
+        bitmap->sb_page = NULL;
+        spin_unlock_irqrestore(&bitmap->lock, flags);
+
+        while (pages--)
+                if (map[pages]->index != 0) /* 0 is sb_page, release it below */
+                        page_cache_release(map[pages]);
+        kfree(map);
+        kfree(attr);
+
+        if (sb_page)
+                page_cache_release(sb_page);
+}
+
+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)
+{
+        struct page_list *item = NULL;
+
+        spin_lock(&bitmap->write_lock);
+        if (list_empty(head))
+                goto out;
+        item = list_entry(head->prev, struct page_list, list);
+        list_del(head->prev);
+out:
+        spin_unlock(&bitmap->write_lock);
+        return item;
+}
+
+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);
+                }
+        }
+
+        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)
+{
+        struct file *file;
+        struct inode *inode;
+        unsigned long flags;
+
+        spin_lock_irqsave(&bitmap->lock, flags);
+        file = bitmap->file;
+        bitmap->file = NULL;
+        spin_unlock_irqrestore(&bitmap->lock, flags);
+
+        bitmap_stop_daemons(bitmap);
+
+        drain_write_queues(bitmap);
+
+        bitmap_file_unmap(bitmap);
+
+        if (file) {
+                inode = file->f_mapping->host;
+                spin_lock(&inode->i_lock);
+                atomic_set(&inode->i_writecount, 1); /* allow writes again */
+                spin_unlock(&inode->i_lock);
+                fput(file);
+        }
+}
+
+
+/*
+ * bitmap_file_kick - if an error occurs while manipulating the bitmap file
+ * then it is no longer reliable, so we stop using it and we mark the file
+ * as failed in the superblock
+ */
+static void bitmap_file_kick(struct bitmap *bitmap)
+{
+        char *path, *ptr = NULL;
+
+        bitmap_mask_state(bitmap, BITMAP_STALE, MASK_SET);
+        bitmap_update_sb(bitmap);
+
+        path = kmalloc(PAGE_SIZE, GFP_KERNEL);
+        if (path)
+                ptr = file_path(bitmap->file, path, PAGE_SIZE);
+
+        printk(KERN_ALERT "%s: kicking failed bitmap file %s from array!\n",
+                bmname(bitmap), ptr ? ptr : "");
+
+        kfree(path);
+
+        bitmap_file_put(bitmap);
+
+        return;
+}
+
+enum bitmap_page_attr {
+        BITMAP_PAGE_DIRTY = 1, // there are set bits that need to be synced
+        BITMAP_PAGE_CLEAN = 2, // there are bits that might need to be cleared
+        BITMAP_PAGE_NEEDWRITE=4, // there are cleared bits that need to be synced
+};
+
+static inline void set_page_attr(struct bitmap *bitmap, struct page *page,
+                                enum bitmap_page_attr attr)
+{
+        bitmap->filemap_attr[page->index] |= attr;
+}
+
+static inline void clear_page_attr(struct bitmap *bitmap, struct page *page,
+                                enum bitmap_page_attr attr)
+{
+        bitmap->filemap_attr[page->index] &= ~attr;
+}
+
+static inline unsigned long get_page_attr(struct bitmap *bitmap, struct page *page)
+{
+        return bitmap->filemap_attr[page->index];
+}
+
+/*
+ * 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
+ *
+ * we set the bit immediately, then we record the page number so that
+ * when an unplug occurs, we can flush the dirty pages out to disk
+ */
+static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
+{
+        unsigned long bit;
+        struct page *page;
+        void *kaddr;
+        unsigned long chunk = block >> CHUNK_BLOCK_SHIFT(bitmap);
+
+        if (!bitmap->file || !bitmap->filemap) {
+                return;
+        }
+
+        page = filemap_get_page(bitmap, chunk);
+        bit = file_page_offset(chunk);
+
+
+        /* make sure the page stays cached until it gets written out */
+        if (! (get_page_attr(bitmap, page) & BITMAP_PAGE_DIRTY))
+                page_cache_get(page);
+
+        /* set the bit */
+        kaddr = kmap_atomic(page, KM_USER0);
+        set_bit(bit, kaddr);
+        kunmap_atomic(kaddr, KM_USER0);
+        PRINTK("set file bit %lu page %lu\n", bit, page->index);
+
+        /* record page number so it gets flushed to disk when unplug occurs */
+        set_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
+
+}
+
+/* this gets called when the md device is ready to unplug its underlying
+ * (slave) device queues -- before we let any writes go down, we need to
+ * sync the dirty pages of the bitmap file to disk */
+int bitmap_unplug(struct bitmap *bitmap)
+{
+        unsigned long i, attr, flags;
+        struct page *page;
+        int wait = 0;
+
+        if (!bitmap)
+                return 0;
+
+        /* 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->file_pages; i++) {
+                spin_lock_irqsave(&bitmap->lock, flags);
+                if (!bitmap->file || !bitmap->filemap) {
+                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                        return 0;
+                }
+                page = bitmap->filemap[i];
+                attr = get_page_attr(bitmap, page);
+                clear_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
+                clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
+                if ((attr & BITMAP_PAGE_DIRTY))
+                        wait = 1;
+                spin_unlock_irqrestore(&bitmap->lock, flags);
+
+                if (attr & (BITMAP_PAGE_DIRTY | BITMAP_PAGE_NEEDWRITE))
+                        write_page(page, 0);
+        }
+        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,
+                        wake_up_process(bitmap->writeback_daemon->tsk));
+                spin_unlock_irq(&bitmap->write_lock);
+        }
+        return 0;
+}
+
+static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset,
+        unsigned long sectors, int set);
+/* * 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
+ * Special cases:
+ *   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.
+ */
+static int bitmap_init_from_disk(struct bitmap *bitmap)
+{
+        unsigned long i, chunks, index, oldindex, bit;
+        struct page *page = NULL, *oldpage = NULL;
+        unsigned long num_pages, bit_cnt = 0;
+        struct file *file;
+        unsigned long bytes, offset, dummy;
+        int outofdate;
+        int ret = -ENOSPC;
+
+        chunks = bitmap->chunks;
+        file = bitmap->file;
+
+        if (!file) { /* no file, dirty all the in-memory bits */
+                printk(KERN_INFO "%s: no bitmap file, doing full recovery\n",
+                        bmname(bitmap));
+                bitmap_set_memory_bits(bitmap, 0,
+                                       chunks << CHUNK_BLOCK_SHIFT(bitmap), 1);
+                return 0;
+        }
+
+#if INJECT_FAULTS_3
+        outofdate = 1;
+#else
+        outofdate = bitmap->flags & BITMAP_STALE;
+#endif
+        if (outofdate)
+                printk(KERN_INFO "%s: bitmap file is out of date, doing full "
+                        "recovery\n", bmname(bitmap));
+
+        bytes = (chunks + 7) / 8;
+        num_pages = (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
+        if (i_size_read(file->f_mapping->host) < bytes + sizeof(bitmap_super_t)) {
+                printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
+                        bmname(bitmap),
+                        (unsigned long) i_size_read(file->f_mapping->host),
+                        bytes + sizeof(bitmap_super_t));
+                goto out;
+        }
+        num_pages++;
+        bitmap->filemap = kmalloc(sizeof(struct page *) * num_pages, GFP_KERNEL);
+        if (!bitmap->filemap) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        bitmap->filemap_attr = kmalloc(sizeof(long) * num_pages, GFP_KERNEL);
+        if (!bitmap->filemap_attr) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        memset(bitmap->filemap_attr, 0, sizeof(long) * num_pages);
+
+        oldindex = ~0L;
+
+        for (i = 0; i < chunks; i++) {
+                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
+                                 * contains some bits (PAGE_SIZE != sizeof sb)
+                                 * we've already read it in, so just use it
+                                 */
+                                page = bitmap->sb_page;
+                                offset = sizeof(bitmap_super_t);
+                        } else {
+                                page = read_page(file, index, &dummy);
+                                if (IS_ERR(page)) { /* read error */
+                                        ret = PTR_ERR(page);
+                                        goto out;
+                                }
+                                offset = 0;
+                        }
+                        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);
+                                ret = write_page(page, 1);
+                                if (ret) {
+                                        kunmap(page);
+                                        /* release, page not in filemap yet */
+                                        page_cache_release(page);
+                                        goto out;
+                                }
+                        }
+
+                        bitmap->filemap[bitmap->file_pages++] = page;
+                }
+                if (test_bit(bit, page_address(page))) {
+                        /* if the disk bit is set, set the memory bit */
+                        bitmap_set_memory_bits(bitmap,
+                                        i << CHUNK_BLOCK_SHIFT(bitmap), 1, 1);
+                        bit_cnt++;
+                }
+#if 0
+                else
+                        bitmap_set_memory_bits(bitmap,
+                                       i << CHUNK_BLOCK_SHIFT(bitmap), 1, 0);
+#endif
+        }
+
+        /* everything went OK */
+        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);
+        }
+
+out:
+        printk(KERN_INFO "%s: bitmap initialized from disk: "
+                "read %lu/%lu pages, set %lu bits, status: %d\n",
+                bmname(bitmap), bitmap->file_pages, num_pages, bit_cnt, ret);
+
+        return ret;
+}
+
+
+static void bitmap_count_page(struct bitmap *bitmap, sector_t offset, int inc)
+{
+        sector_t chunk = offset >> CHUNK_BLOCK_SHIFT(bitmap);
+        unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
+        bitmap->bp[page].count += inc;
+/*
+        if (page == 0) printk("count page 0, offset %llu: %d gives %d\n",
+                              (unsigned long long)offset, inc, bitmap->bp[page].count);
+*/
+        bitmap_checkfree(bitmap, page);
+}
+static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
+                                            sector_t offset, int *blocks,
+                                            int create);
+
+/*
+ * bitmap daemon -- periodically wakes up to clean bits and flush pages
+ *                      out to disk
+ */
+
+int bitmap_daemon_work(struct bitmap *bitmap)
+{
+        unsigned long bit, j;
+        unsigned long flags;
+        struct page *page = NULL, *lastpage = NULL;
+        int err = 0;
+        int blocks;
+        int attr;
+
+        if (bitmap == NULL)
+                return 0;
+        if (time_before(jiffies, bitmap->daemon_lastrun + bitmap->daemon_sleep*HZ))
+                return 0;
+        bitmap->daemon_lastrun = jiffies;
+
+        for (j = 0; j < bitmap->chunks; j++) {
+                bitmap_counter_t *bmc;
+                spin_lock_irqsave(&bitmap->lock, flags);
+                if (!bitmap->file || !bitmap->filemap) {
+                        /* error or shutdown */
+                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                        break;
+                }
+
+                page = filemap_get_page(bitmap, j);
+                /* 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);
+                                clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
+                        }
+                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                        if (attr & BITMAP_PAGE_NEEDWRITE) {
+                                if (write_page(page, 0))
+                                        bitmap_file_kick(bitmap);
+                                page_cache_release(page);
+                        }
+                        continue;
+                }
+
+                bit = file_page_offset(j);
+
+                if (page != lastpage) {
+                        /* grab the new page, sync and release the old */
+                        page_cache_get(page);
+                        if (lastpage != NULL) {
+                                if (get_page_attr(bitmap, lastpage) & BITMAP_PAGE_NEEDWRITE) {
+                                        clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
+                                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                                        write_page(lastpage, 0);
+                                } else {
+                                        set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
+                                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                                }
+                                kunmap(lastpage);
+                                page_cache_release(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);
+*/
+                        spin_lock_irqsave(&bitmap->lock, flags);
+                        clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
+                }
+                bmc = bitmap_get_counter(bitmap, j << CHUNK_BLOCK_SHIFT(bitmap),
+                                        &blocks, 0);
+                if (bmc) {
+/*
+  if (j < 100) printk("bitmap: j=%lu, *bmc = 0x%x\n", j, *bmc);
+*/
+                        if (*bmc == 2) {
+                                *bmc=1; /* maybe clear the bit next time */
+                                set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
+                        } else if (*bmc == 1) {
+                                /* we can clear the bit */
+                                *bmc = 0;
+                                bitmap_count_page(bitmap, j << CHUNK_BLOCK_SHIFT(bitmap),
+                                                  -1);
+
+                                /* clear the bit */
+                                clear_bit(bit, page_address(page));
+                        }
+                }
+                spin_unlock_irqrestore(&bitmap->lock, flags);
+        }
+
+        /* 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);
+                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                        write_page(lastpage, 0);
+                } else {
+                        set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
+                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                }
+
+                page_cache_release(lastpage);
+        }
+
+        return err;
+}
+
+static void daemon_exit(struct bitmap *bitmap, mdk_thread_t **daemon)
+{
+        mdk_thread_t *dmn;
+        unsigned long flags;
+
+        /* if no one is waiting on us, we'll free the md thread struct
+         * and exit, otherwise we let the waiter clean things up */
+        spin_lock_irqsave(&bitmap->lock, flags);
+        if ((dmn = *daemon)) { /* no one is waiting, cleanup and exit */
+                *daemon = NULL;
+                spin_unlock_irqrestore(&bitmap->lock, flags);
+                kfree(dmn);
+                complete_and_exit(NULL, 0); /* do_exit not exported */
+        }
+        spin_unlock_irqrestore(&bitmap->lock, flags);
+}
+
+static void bitmap_writeback_daemon(mddev_t *mddev)
+{
+        struct bitmap *bitmap = mddev->bitmap;
+        struct page *page;
+        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;
+                }
+
+                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;
+                        }
+                }
+        }
+out:
+        if (err) {
+                printk(KERN_INFO "%s: bitmap writeback daemon exiting (%d)\n",
+                        bmname(bitmap), err);
+                daemon_exit(bitmap, &bitmap->writeback_daemon);
+        }
+        return;
+}
+
+static int bitmap_start_daemon(struct bitmap *bitmap, mdk_thread_t **ptr,
+                                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);
+
+#if INJECT_FATAL_FAULT_2
+        daemon = NULL;
+#else
+        sprintf(namebuf, "%%s_%s", name);
+        daemon = md_register_thread(func, bitmap->mddev, namebuf);
+#endif
+        if (!daemon) {
+                printk(KERN_ERR "%s: failed to start bitmap daemon\n",
+                        bmname(bitmap));
+                return -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, bitmap->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;
+}
+
+static void bitmap_stop_daemon(struct bitmap *bitmap, mdk_thread_t **ptr)
+{
+        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 */
+}
+
+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);
+}
+
+static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
+                                            sector_t offset, int *blocks,
+                                            int create)
+{
+        /* If 'create', we might release the lock and reclaim it.
+         * The lock must have been taken with interrupts enabled.
+         * If !create, we don't release the lock.
+         */
+        sector_t chunk = offset >> CHUNK_BLOCK_SHIFT(bitmap);
+        unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
+        unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
+        sector_t csize;
+
+        if (bitmap_checkpage(bitmap, page, create) < 0) {
+                csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap));
+                *blocks = csize - (offset & (csize- 1));
+                return NULL;
+        }
+        /* now locked ... */
+
+        if (bitmap->bp[page].hijacked) { /* hijacked pointer */
+                /* should we use the first or second counter field
+                 * of the hijacked pointer? */
+                int hi = (pageoff > PAGE_COUNTER_MASK);
+                csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap) +
+                                          PAGE_COUNTER_SHIFT - 1);
+                *blocks = csize - (offset & (csize- 1));
+                return  &((bitmap_counter_t *)
+                          &bitmap->bp[page].map)[hi];
+        } else { /* page is allocated */
+                csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap));
+                *blocks = csize - (offset & (csize- 1));
+                return (bitmap_counter_t *)
+                        &(bitmap->bp[page].map[pageoff]);
+        }
+}
+
+int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors)
+{
+        if (!bitmap) return 0;
+        while (sectors) {
+                int blocks;
+                bitmap_counter_t *bmc;
+
+                spin_lock_irq(&bitmap->lock);
+                bmc = bitmap_get_counter(bitmap, offset, &blocks, 1);
+                if (!bmc) {
+                        spin_unlock_irq(&bitmap->lock);
+                        return 0;
+                }
+
+                switch(*bmc) {
+                case 0:
+                        bitmap_file_set_bit(bitmap, offset);
+                        bitmap_count_page(bitmap,offset, 1);
+                        blk_plug_device(bitmap->mddev->queue);
+                        /* fall through */
+                case 1:
+                        *bmc = 2;
+                }
+                if ((*bmc & COUNTER_MAX) == COUNTER_MAX) BUG();
+                (*bmc)++;
+
+                spin_unlock_irq(&bitmap->lock);
+
+                offset += blocks;
+                if (sectors > blocks)
+                        sectors -= blocks;
+                else sectors = 0;
+        }
+        return 0;
+}
+
+void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
+                     int success)
+{
+        if (!bitmap) return;
+        while (sectors) {
+                int blocks;
+                unsigned long flags;
+                bitmap_counter_t *bmc;
+
+                spin_lock_irqsave(&bitmap->lock, flags);
+                bmc = bitmap_get_counter(bitmap, offset, &blocks, 0);
+                if (!bmc) {
+                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                        return;
+                }
+
+                if (!success && ! (*bmc & NEEDED_MASK))
+                        *bmc |= NEEDED_MASK;
+
+                (*bmc)--;
+                if (*bmc <= 2) {
+                        set_page_attr(bitmap,
+                                      filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
+                                      BITMAP_PAGE_CLEAN);
+                }
+                spin_unlock_irqrestore(&bitmap->lock, flags);
+                offset += blocks;
+                if (sectors > blocks)
+                        sectors -= blocks;
+                else sectors = 0;
+        }
+}
+
+int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks)
+{
+        bitmap_counter_t *bmc;
+        int rv;
+        if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
+                *blocks = 1024;
+                return 1; /* always resync if no bitmap */
+        }
+        spin_lock_irq(&bitmap->lock);
+        bmc = bitmap_get_counter(bitmap, offset, blocks, 0);
+        rv = 0;
+        if (bmc) {
+                /* locked */
+                if (RESYNC(*bmc))
+                        rv = 1;
+                else if (NEEDED(*bmc)) {
+                        rv = 1;
+                        *bmc |= RESYNC_MASK;
+                        *bmc &= ~NEEDED_MASK;
+                }
+        }
+        spin_unlock_irq(&bitmap->lock);
+        return rv;
+}
+
+void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted)
+{
+        bitmap_counter_t *bmc;
+        unsigned long flags;
+/*
+        if (offset == 0) printk("bitmap_end_sync 0 (%d)\n", aborted);
+*/      if (bitmap == NULL) {
+                *blocks = 1024;
+                return;
+        }
+        spin_lock_irqsave(&bitmap->lock, flags);
+        bmc = bitmap_get_counter(bitmap, offset, blocks, 0);
+        if (bmc == NULL)
+                goto unlock;
+        /* locked */
+/*
+        if (offset == 0) printk("bitmap_end sync found 0x%x, blocks %d\n", *bmc, *blocks);
+*/
+        if (RESYNC(*bmc)) {
+                *bmc &= ~RESYNC_MASK;
+
+                if (!NEEDED(*bmc) && aborted)
+                        *bmc |= NEEDED_MASK;
+                else {
+                        if (*bmc <= 2) {
+                                set_page_attr(bitmap,
+                                              filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
+                                              BITMAP_PAGE_CLEAN);
+                        }
+                }
+        }
+ unlock:
+        spin_unlock_irqrestore(&bitmap->lock, flags);
+}
+
+void bitmap_close_sync(struct bitmap *bitmap)
+{
+        /* Sync has finished, and any bitmap chunks that weren't synced
+         * properly have been aborted.  It remains to us to clear the
+         * RESYNC bit wherever it is still on
+         */
+        sector_t sector = 0;
+        int blocks;
+        if (!bitmap) return;
+        while (sector < bitmap->mddev->resync_max_sectors) {
+                bitmap_end_sync(bitmap, sector, &blocks, 0);
+/*
+                if (sector < 500) printk("bitmap_close_sync: sec %llu blks %d\n",
+                                         (unsigned long long)sector, blocks);
+*/              sector += blocks;
+        }
+}
+
+static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset,
+                                   unsigned long sectors, int set)
+{
+        /* For each chunk covered by any of these sectors, set the
+         * resync needed bit, and the counter to 1.  They should all
+         * be 0 at this point
+         */
+        while (sectors) {
+                int secs;
+                bitmap_counter_t *bmc;
+                spin_lock_irq(&bitmap->lock);
+                bmc = bitmap_get_counter(bitmap, offset, &secs, 1);
+                if (!bmc) {
+                        spin_unlock_irq(&bitmap->lock);
+                        return;
+                }
+                if (set && !NEEDED(*bmc)) {
+                        BUG_ON(*bmc);
+                        *bmc = NEEDED_MASK | 1;
+                        bitmap_count_page(bitmap, offset, 1);
+                }
+                spin_unlock_irq(&bitmap->lock);
+                if (sectors > secs)
+                        sectors -= secs;
+                else
+                        sectors = 0;
+        }
+}
+
+/* dirty the entire bitmap */
+int bitmap_setallbits(struct bitmap *bitmap)
+{
+        unsigned long flags;
+        unsigned long j;
+
+        /* dirty the in-memory bitmap */
+        bitmap_set_memory_bits(bitmap, 0, bitmap->chunks << CHUNK_BLOCK_SHIFT(bitmap), 1);
+
+        /* dirty the bitmap file */
+        for (j = 0; j < bitmap->file_pages; j++) {
+                struct page *page = bitmap->filemap[j];
+
+                spin_lock_irqsave(&bitmap->lock, flags);
+                page_cache_get(page);
+                spin_unlock_irqrestore(&bitmap->lock, flags);
+                memset(kmap(page), 0xff, PAGE_SIZE);
+                kunmap(page);
+                write_page(page, 0);
+        }
+
+        return 0;
+}
+
+/*
+ * free memory that was allocated
+ */
+void bitmap_destroy(mddev_t *mddev)
+{
+        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);
+
+        bp = bitmap->bp;
+        pages = bitmap->pages;
+
+        /* free all allocated memory */
+
+        mempool_destroy(bitmap->write_pool);
+
+        if (bp) /* deallocate the page memory */
+                for (k = 0; k < pages; k++)
+                        if (bp[k].map && !bp[k].hijacked)
+                                kfree(bp[k].map);
+        kfree(bp);
+        kfree(bitmap);
+}
+
+/*
+ * initialize the bitmap structure
+ * if this returns an error, bitmap_destroy must be called to do clean up
+ */
+int bitmap_create(mddev_t *mddev)
+{
+        struct bitmap *bitmap;
+        unsigned long blocks = mddev->resync_max_sectors;
+        unsigned long chunks;
+        unsigned long pages;
+        struct file *file = mddev->bitmap_file;
+        int err;
+
+        BUG_ON(sizeof(bitmap_super_t) != 256);
+
+        if (!file) /* bitmap disabled, nothing to do */
+                return 0;
+
+        bitmap = kmalloc(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_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,
+                                write_pool_free, NULL);
+        if (!bitmap->write_pool)
+                return -ENOMEM;
+
+        bitmap->file = file;
+        get_file(file);
+        /* read superblock from bitmap file (this sets bitmap->chunksize) */
+        err = bitmap_read_sb(bitmap);
+        if (err)
+                return err;
+
+        bitmap->chunkshift = find_first_bit(&bitmap->chunksize,
+                                        sizeof(bitmap->chunksize));
+
+        /* now that chunksize and chunkshift are set, we can use these macros */
+        chunks = (blocks + CHUNK_BLOCK_RATIO(bitmap) - 1) /
+                        CHUNK_BLOCK_RATIO(bitmap);
+        pages = (chunks + PAGE_COUNTER_RATIO - 1) / PAGE_COUNTER_RATIO;
+
+        BUG_ON(!pages);
+
+        bitmap->chunks = chunks;
+        bitmap->pages = pages;
+        bitmap->missing_pages = pages;
+        bitmap->counter_bits = COUNTER_BITS;
+
+        bitmap->syncchunk = ~0UL;
+
+#if INJECT_FATAL_FAULT_1
+        bitmap->bp = NULL;
+#else
+        bitmap->bp = kmalloc(pages * sizeof(*bitmap->bp), GFP_KERNEL);
+#endif
+        if (!bitmap->bp)
+                return -ENOMEM;
+        memset(bitmap->bp, 0, pages * sizeof(*bitmap->bp));
+
+        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);
+        if (err)
+                return err;
+
+        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;
+        return bitmap_update_sb(bitmap);
+}
+
+/* the bitmap API -- for raid personalities */
+EXPORT_SYMBOL(bitmap_startwrite);
+EXPORT_SYMBOL(bitmap_endwrite);
+EXPORT_SYMBOL(bitmap_start_sync);
+EXPORT_SYMBOL(bitmap_end_sync);
+EXPORT_SYMBOL(bitmap_unplug);
+EXPORT_SYMBOL(bitmap_close_sync);
+EXPORT_SYMBOL(bitmap_daemon_work);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index fa608a1a5c20..c402f6cc7047 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -19,6 +19,9 @@
 
      Neil Brown <neilb@cse.unsw.edu.au>.
 
+   - persistent bitmap code
+     Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
+
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2, or (at your option)
@@ -33,6 +36,7 @@
 #include <linux/config.h>
 #include <linux/linkage.h>
 #include <linux/raid/md.h>
+#include <linux/raid/bitmap.h>
 #include <linux/sysctl.h>
 #include <linux/devfs_fs_kernel.h>
 #include <linux/buffer_head.h> /* for invalidate_bdev */
@@ -40,6 +44,8 @@
 
 #include <linux/init.h>
 
+#include <linux/file.h>
+
 #ifdef CONFIG_KMOD
 #include <linux/kmod.h>
 #endif
@@ -1198,8 +1204,11 @@ void md_print_devices(void)
         printk("md:     * <COMPLETE RAID STATE PRINTOUT> *\n");
         printk("md:     **********************************\n");
         ITERATE_MDDEV(mddev,tmp) {
-                printk("%s: ", mdname(mddev));
 
+                if (mddev->bitmap)
+                        bitmap_print_sb(mddev->bitmap);
+                else
+                        printk("%s: ", mdname(mddev));
                 ITERATE_RDEV(mddev,rdev,tmp2)
                         printk("<%s>", bdevname(rdev->bdev,b));
                 printk("\n");
@@ -1287,7 +1296,7 @@ repeat:
                 "md: updating %s RAID superblock on device (in sync %d)\n",
                 mdname(mddev),mddev->in_sync);
 
-        err = 0;
+        err = bitmap_update_sb(mddev->bitmap);
         ITERATE_RDEV(mddev,rdev,tmp) {
                 char b[BDEVNAME_SIZE];
                 dprintk(KERN_INFO "md: ");
@@ -1624,12 +1633,19 @@ static int do_md_run(mddev_t * mddev)
 
         mddev->resync_max_sectors = mddev->size << 1; /* may be over-ridden by personality */
 
-        err = mddev->pers->run(mddev);
+        /* before we start the array running, initialise the bitmap */
+        err = bitmap_create(mddev);
+        if (err)
+                printk(KERN_ERR "%s: failed to create bitmap (%d)\n",
+                        mdname(mddev), err);
+        else
+                err = mddev->pers->run(mddev);
         if (err) {
                 printk(KERN_ERR "md: pers->run() failed ...\n");
                 module_put(mddev->pers->owner);
                 mddev->pers = NULL;
-                return -EINVAL;
+                bitmap_destroy(mddev);
+                return err;
         }
         atomic_set(&mddev->writes_pending,0);
         mddev->safemode = 0;
@@ -1742,6 +1758,14 @@ static int do_md_stop(mddev_t * mddev, int ro)
                 if (ro)
                         set_disk_ro(disk, 1);
         }
+
+        bitmap_destroy(mddev);
+        if (mddev->bitmap_file) {
+                atomic_set(&mddev->bitmap_file->f_dentry->d_inode->i_writecount, 1);
+                fput(mddev->bitmap_file);
+                mddev->bitmap_file = NULL;
+        }
+
         /*
          * Free resources if final stop
          */
@@ -2000,6 +2024,42 @@ static int get_array_info(mddev_t * mddev, void __user * arg)
         return 0;
 }
 
+static int get_bitmap_file(mddev_t * mddev, void * arg)
+{
+        mdu_bitmap_file_t *file = NULL; /* too big for stack allocation */
+        char *ptr, *buf = NULL;
+        int err = -ENOMEM;
+
+        file = kmalloc(sizeof(*file), GFP_KERNEL);
+        if (!file)
+                goto out;
+
+        /* bitmap disabled, zero the first byte and copy out */
+        if (!mddev->bitmap || !mddev->bitmap->file) {
+                file->pathname[0] = '\0';
+                goto copy_out;
+        }
+
+        buf = kmalloc(sizeof(file->pathname), GFP_KERNEL);
+        if (!buf)
+                goto out;
+
+        ptr = file_path(mddev->bitmap->file, buf, sizeof(file->pathname));
+        if (!ptr)
+                goto out;
+
+        strcpy(file->pathname, ptr);
+
+copy_out:
+        err = 0;
+        if (copy_to_user(arg, file, sizeof(*file)))
+                err = -EFAULT;
+out:
+        kfree(buf);
+        kfree(file);
+        return err;
+}
+
 static int get_disk_info(mddev_t * mddev, void __user * arg)
 {
         mdu_disk_info_t info;
@@ -2275,6 +2335,48 @@ abort_export:
         return err;
 }
 
+/* similar to deny_write_access, but accounts for our holding a reference
+ * to the file ourselves */
+static int deny_bitmap_write_access(struct file * file)
+{
+        struct inode *inode = file->f_mapping->host;
+
+        spin_lock(&inode->i_lock);
+        if (atomic_read(&inode->i_writecount) > 1) {
+                spin_unlock(&inode->i_lock);
+                return -ETXTBSY;
+        }
+        atomic_set(&inode->i_writecount, -1);
+        spin_unlock(&inode->i_lock);
+
+        return 0;
+}
+
+static int set_bitmap_file(mddev_t *mddev, int fd)
+{
+        int err;
+
+        if (mddev->pers)
+                return -EBUSY;
+
+        mddev->bitmap_file = fget(fd);
+
+        if (mddev->bitmap_file == NULL) {
+                printk(KERN_ERR "%s: error: failed to get bitmap file\n",
+                        mdname(mddev));
+                return -EBADF;
+        }
+
+        err = deny_bitmap_write_access(mddev->bitmap_file);
+        if (err) {
+                printk(KERN_ERR "%s: error: bitmap file is already in use\n",
+                        mdname(mddev));
+                fput(mddev->bitmap_file);
+                mddev->bitmap_file = NULL;
+        }
+        return err;
+}
+
 /*
  * set_array_info is used two different ways
  * The original usage is when creating a new array.
@@ -2586,8 +2688,10 @@ static int md_ioctl(struct inode *inode, struct file *file,
         /*
          * Commands querying/configuring an existing array:
          */
-        /* if we are initialised yet, only ADD_NEW_DISK or STOP_ARRAY is allowed */
-        if (!mddev->raid_disks && cmd != ADD_NEW_DISK && cmd != STOP_ARRAY && cmd != RUN_ARRAY) {
+        /* if we are not initialised yet, only ADD_NEW_DISK, STOP_ARRAY,
+         * RUN_ARRAY, and SET_BITMAP_FILE are allowed */
+        if (!mddev->raid_disks && cmd != ADD_NEW_DISK && cmd != STOP_ARRAY
+                        && cmd != RUN_ARRAY && cmd != SET_BITMAP_FILE) {
                 err = -ENODEV;
                 goto abort_unlock;
         }
@@ -2601,6 +2705,10 @@ static int md_ioctl(struct inode *inode, struct file *file,
                         err = get_array_info(mddev, argp);
                         goto done_unlock;
 
+                case GET_BITMAP_FILE:
+                        err = get_bitmap_file(mddev, (void *)arg);
+                        goto done_unlock;
+
                 case GET_DISK_INFO:
                         err = get_disk_info(mddev, argp);
                         goto done_unlock;
@@ -2681,6 +2789,10 @@ static int md_ioctl(struct inode *inode, struct file *file,
                         err = do_md_run (mddev);
                         goto done_unlock;
 
+                case SET_BITMAP_FILE:
+                        err = set_bitmap_file(mddev, (int)arg);
+                        goto done_unlock;
+
                 default:
                         if (_IOC_TYPE(cmd) == MD_MAJOR)
                                 printk(KERN_WARNING "md: %s(pid %d) used"
@@ -2792,8 +2904,9 @@ static int md_thread(void * arg)
         while (thread->run) {
                 void (*run)(mddev_t *);
 
-                wait_event_interruptible(thread->wqueue,
-                                         test_bit(THREAD_WAKEUP, &thread->flags));
+                wait_event_interruptible_timeout(thread->wqueue,
+                                                 test_bit(THREAD_WAKEUP, &thread->flags),
+                                                 thread->timeout);
                 if (current->flags & PF_FREEZE)
                         refrigerator(PF_FREEZE);
 
@@ -2839,6 +2952,7 @@ mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
         thread->run = run;
         thread->mddev = mddev;
         thread->name = name;
+        thread->timeout = MAX_SCHEDULE_TIMEOUT;
         ret = kernel_thread(md_thread, thread, 0);
         if (ret < 0) {
                 kfree(thread);
@@ -2877,13 +2991,13 @@ void md_error(mddev_t *mddev, mdk_rdev_t *rdev)
 
         if (!rdev || rdev->faulty)
                 return;
-
+/*
         dprintk("md_error dev:%s, rdev:(%d:%d), (caller: %p,%p,%p,%p).\n",
                 mdname(mddev),
                 MAJOR(rdev->bdev->bd_dev), MINOR(rdev->bdev->bd_dev),
                 __builtin_return_address(0),__builtin_return_address(1),
                 __builtin_return_address(2),__builtin_return_address(3));
-
+*/
         if (!mddev->pers->error_handler)
                 return;
         mddev->pers->error_handler(mddev,rdev);
@@ -3037,6 +3151,7 @@ static int md_seq_show(struct seq_file *seq, void *v)
         struct list_head *tmp2;
         mdk_rdev_t *rdev;
         int i;
+        struct bitmap *bitmap;
 
         if (v == (void*)1) {
                 seq_printf(seq, "Personalities : ");
@@ -3089,10 +3204,36 @@ static int md_seq_show(struct seq_file *seq, void *v)
                 if (mddev->pers) {
                         mddev->pers->status (seq, mddev);
                         seq_printf(seq, "\n      ");
-                        if (mddev->curr_resync > 2)
+                        if (mddev->curr_resync > 2) {
                                 status_resync (seq, mddev);
-                        else if (mddev->curr_resync == 1 || mddev->curr_resync == 2)
-                                seq_printf(seq, "       resync=DELAYED");
+                                seq_printf(seq, "\n      ");
+                        } else if (mddev->curr_resync == 1 || mddev->curr_resync == 2)
+                                seq_printf(seq, "       resync=DELAYED\n      ");
+                } else
+                        seq_printf(seq, "\n       ");
+
+                if ((bitmap = mddev->bitmap)) {
+                        char *buf, *path;
+                        unsigned long chunk_kb;
+                        unsigned long flags;
+                        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+                        spin_lock_irqsave(&bitmap->lock, flags);
+                        chunk_kb = bitmap->chunksize >> 10;
+                        seq_printf(seq, "bitmap: %lu/%lu pages [%luKB], "
+                                "%lu%s chunk",
+                                bitmap->pages - bitmap->missing_pages,
+                                bitmap->pages,
+                                (bitmap->pages - bitmap->missing_pages)
+                                        << (PAGE_SHIFT - 10),
+                                chunk_kb ? chunk_kb : bitmap->chunksize,
+                                chunk_kb ? "KB" : "B");
+                        if (bitmap->file && buf) {
+                                path = file_path(bitmap->file, buf, PAGE_SIZE);
+                                seq_printf(seq, ", file: %s", path ? path : "");
+                        }
+                        seq_printf(seq, "\n");
+                        spin_unlock_irqrestore(&bitmap->lock, flags);
+                        kfree(buf);
                 }
 
                 seq_printf(seq, "\n");
@@ -3328,7 +3469,8 @@ static void md_do_sync(mddev_t *mddev)
                sysctl_speed_limit_max);
 
         is_mddev_idle(mddev); /* this also initializes IO event counters */
-        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
+        /* we don't use the checkpoint if there's a bitmap */
+        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && !mddev->bitmap)
                 j = mddev->recovery_cp;
         else
                 j = 0;
@@ -3673,6 +3815,8 @@ static int __init md_init(void)
                         " MD_SB_DISKS=%d\n",
                         MD_MAJOR_VERSION, MD_MINOR_VERSION,
                         MD_PATCHLEVEL_VERSION, MAX_MD_DEVS, MD_SB_DISKS);
+        printk(KERN_INFO "md: bitmap version %d.%d\n", BITMAP_MAJOR,
+                        BITMAP_MINOR);
 
         if (register_blkdev(MAJOR_NR, "md"))
                 return -1;
diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
new file mode 100644
index 000000000000..f785cf26cbad
--- /dev/null
+++ b/include/linux/raid/bitmap.h
@@ -0,0 +1,280 @@
+/*
+ * bitmap.h: Copyright (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
+ *
+ * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
+ */
+#ifndef BITMAP_H
+#define BITMAP_H 1
+
+#define BITMAP_MAJOR 3
+#define BITMAP_MINOR 38
+
+/*
+ * in-memory bitmap:
+ *
+ * Use 16 bit block counters to track pending writes to each "chunk".
+ * The 2 high order bits are special-purpose, the first is a flag indicating
+ * whether a resync is needed.  The second is a flag indicating whether a
+ * resync is active.
+ * This means that the counter is actually 14 bits:
+ *
+ * +--------+--------+------------------------------------------------+
+ * | resync | resync |               counter                          |
+ * | needed | active |                                                |
+ * |  (0-1) |  (0-1) |              (0-16383)                         |
+ * +--------+--------+------------------------------------------------+
+ *
+ * The "resync needed" bit is set when:
+ *    a '1' bit is read from storage at startup.
+ *    a write request fails on some drives
+ *    a resync is aborted on a chunk with 'resync active' set
+ * It is cleared (and resync-active set) when a resync starts across all drives
+ * of the chunk.
+ *
+ *
+ * The "resync active" bit is set when:
+ *    a resync is started on all drives, and resync_needed is set.
+ *       resync_needed will be cleared (as long as resync_active wasn't already set).
+ * It is cleared when a resync completes.
+ *
+ * The counter counts pending write requests, plus the on-disk bit.
+ * When the counter is '1' and the resync bits are clear, the on-disk
+ * bit can be cleared aswell, thus setting the counter to 0.
+ * When we set a bit, or in the counter (to start a write), if the fields is
+ * 0, we first set the disk bit and set the counter to 1.
+ *
+ * If the counter is 0, the on-disk bit is clear and the stipe is clean
+ * Anything that dirties the stipe pushes the counter to 2 (at least)
+ * and sets the on-disk bit (lazily).
+ * If a periodic sweep find the counter at 2, it is decremented to 1.
+ * If the sweep find the counter at 1, the on-disk bit is cleared and the
+ * counter goes to zero.
+ *
+ * Also, we'll hijack the "map" pointer itself and use it as two 16 bit block
+ * counters as a fallback when "page" memory cannot be allocated:
+ *
+ * Normal case (page memory allocated):
+ *
+ *     page pointer (32-bit)
+ *
+ *     [ ] ------+
+ *               |
+ *               +-------> [   ][   ]..[   ] (4096 byte page == 2048 counters)
+ *                          c1   c2    c2048
+ *
+ * Hijacked case (page memory allocation failed):
+ *
+ *     hijacked page pointer (32-bit)
+ *
+ *     [                  ][              ] (no page memory allocated)
+ *      counter #1 (16-bit) counter #2 (16-bit)
+ *
+ */
+
+#ifdef __KERNEL__
+
+#define PAGE_BITS (PAGE_SIZE << 3)
+#define PAGE_BIT_SHIFT (PAGE_SHIFT + 3)
+
+typedef __u16 bitmap_counter_t;
+#define COUNTER_BITS 16
+#define COUNTER_BIT_SHIFT 4
+#define COUNTER_BYTE_RATIO (COUNTER_BITS / 8)
+#define COUNTER_BYTE_SHIFT (COUNTER_BIT_SHIFT - 3)
+
+#define NEEDED_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 1)))
+#define RESYNC_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 2)))
+#define COUNTER_MAX ((bitmap_counter_t) RESYNC_MASK - 1)
+#define NEEDED(x) (((bitmap_counter_t) x) & NEEDED_MASK)
+#define RESYNC(x) (((bitmap_counter_t) x) & RESYNC_MASK)
+#define COUNTER(x) (((bitmap_counter_t) x) & COUNTER_MAX)
+
+/* how many counters per page? */
+#define PAGE_COUNTER_RATIO (PAGE_BITS / COUNTER_BITS)
+/* same, except a shift value for more efficient bitops */
+#define PAGE_COUNTER_SHIFT (PAGE_BIT_SHIFT - COUNTER_BIT_SHIFT)
+/* same, except a mask value for more efficient bitops */
+#define PAGE_COUNTER_MASK  (PAGE_COUNTER_RATIO - 1)
+
+#define BITMAP_BLOCK_SIZE 512
+#define BITMAP_BLOCK_SHIFT 9
+
+/* how many blocks per chunk? (this is variable) */
+#define CHUNK_BLOCK_RATIO(bitmap) ((bitmap)->chunksize >> BITMAP_BLOCK_SHIFT)
+#define CHUNK_BLOCK_SHIFT(bitmap) ((bitmap)->chunkshift - BITMAP_BLOCK_SHIFT)
+#define CHUNK_BLOCK_MASK(bitmap) (CHUNK_BLOCK_RATIO(bitmap) - 1)
+
+/* when hijacked, the counters and bits represent even larger "chunks" */
+/* there will be 1024 chunks represented by each counter in the page pointers */
+#define PAGEPTR_BLOCK_RATIO(bitmap) \
+                        (CHUNK_BLOCK_RATIO(bitmap) << PAGE_COUNTER_SHIFT >> 1)
+#define PAGEPTR_BLOCK_SHIFT(bitmap) \
+                        (CHUNK_BLOCK_SHIFT(bitmap) + PAGE_COUNTER_SHIFT - 1)
+#define PAGEPTR_BLOCK_MASK(bitmap) (PAGEPTR_BLOCK_RATIO(bitmap) - 1)
+
+/*
+ * on-disk bitmap:
+ *
+ * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
+ * file a page at a time. There's a superblock at the start of the file.
+ */
+
+/* map chunks (bits) to file pages - offset by the size of the superblock */
+#define CHUNK_BIT_OFFSET(chunk) ((chunk) + (sizeof(bitmap_super_t) << 3))
+
+#endif
+
+/*
+ * bitmap structures:
+ */
+
+#define BITMAP_MAGIC 0x6d746962
+
+/* use these for bitmap->flags and bitmap->sb->state bit-fields */
+enum bitmap_state {
+        BITMAP_ACTIVE = 0x001, /* the bitmap is in use */
+        BITMAP_STALE  = 0x002  /* the bitmap file is out of date or had -EIO */
+};
+
+/* the superblock at the front of the bitmap file -- little endian */
+typedef struct bitmap_super_s {
+        __u32 magic;        /*  0  BITMAP_MAGIC */
+        __u32 version;      /*  4  the bitmap major for now, could change... */
+        __u8  uuid[16];     /*  8  128 bit uuid - must match md device uuid */
+        __u64 events;       /* 24  event counter for the bitmap (1)*/
+        __u64 events_cleared;/*32  event counter when last bit cleared (2) */
+        __u64 sync_size;    /* 40  the size of the md device's sync range(3) */
+        __u32 state;        /* 48  bitmap state information */
+        __u32 chunksize;    /* 52  the bitmap chunk size in bytes */
+        __u32 daemon_sleep; /* 56  seconds between disk flushes */
+
+        __u8  pad[256 - 60]; /* set to zero */
+} bitmap_super_t;
+
+/* notes:
+ * (1) This event counter is updated before the eventcounter in the md superblock
+ *    When a bitmap is loaded, it is only accepted if this event counter is equal
+ *    to, or one greater than, the event counter in the superblock.
+ * (2) This event counter is updated when the other one is *if*and*only*if* the
+ *    array is not degraded.  As bits are not cleared when the array is degraded,
+ *    this represents the last time that any bits were cleared.
+ *    If a device is being added that has an event count with this value or
+ *    higher, it is accepted as conforming to the bitmap.
+ * (3)This is the number of sectors represented by the bitmap, and is the range that
+ *    resync happens across.  For raid1 and raid5/6 it is the size of individual
+ *    devices.  For raid10 it is the size of the array.
+ */
+
+#ifdef __KERNEL__
+
+/* the in-memory bitmap is represented by bitmap_pages */
+struct bitmap_page {
+        /*
+         * map points to the actual memory page
+         */
+        char *map;
+        /*
+         * in emergencies (when map cannot be alloced), hijack the map
+         * pointer and use it as two counters itself
+         */
+        unsigned int hijacked:1;
+        /*
+         * count of dirty bits on the page
+         */
+        unsigned int  count:31;
+};
+
+/* keep track of bitmap file pages that have pending writes on them */
+struct page_list {
+        struct list_head list;
+        struct page *page;
+};
+
+/* the main bitmap structure - one per mddev */
+struct bitmap {
+        struct bitmap_page *bp;
+        unsigned long pages; /* total number of pages in the bitmap */
+        unsigned long missing_pages; /* number of pages not yet allocated */
+
+        mddev_t *mddev; /* the md device that the bitmap is for */
+
+        int counter_bits; /* how many bits per block counter */
+
+        /* bitmap chunksize -- how much data does each bit represent? */
+        unsigned long chunksize;
+        unsigned long chunkshift; /* chunksize = 2^chunkshift (for bitops) */
+        unsigned long chunks; /* total number of data chunks for the array */
+
+        /* We hold a count on the chunk currently being synced, and drop
+         * it when the last block is started.  If the resync is aborted
+         * midway, we need to be able to drop that count, so we remember
+         * the counted chunk..
+         */
+        unsigned long syncchunk;
+
+        __u64   events_cleared;
+
+        /* bitmap spinlock */
+        spinlock_t lock;
+
+        struct file *file; /* backing disk file */
+        struct page *sb_page; /* cached copy of the bitmap file superblock */
+        struct page **filemap; /* list of cache pages for the file */
+        unsigned long *filemap_attr; /* attributes associated w/ filemap pages */
+        unsigned long file_pages; /* number of pages in the file */
+
+        unsigned long flags;
+
+        /*
+         * the bitmap daemon - periodically wakes up and sweeps the bitmap
+         * file, cleaning up bits and flushing out pages to disk as necessary
+         */
+        unsigned long daemon_lastrun; /* jiffies of last run */
+        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
+         */
+        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;
+};
+
+/* the bitmap API */
+
+/* these are used only by md/bitmap */
+int  bitmap_create(mddev_t *mddev);
+void bitmap_destroy(mddev_t *mddev);
+int  bitmap_active(struct bitmap *bitmap);
+
+char *file_path(struct file *file, char *buf, int count);
+void bitmap_print_sb(struct bitmap *bitmap);
+int bitmap_update_sb(struct bitmap *bitmap);
+
+int  bitmap_setallbits(struct bitmap *bitmap);
+
+/* these are exported */
+int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors);
+void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
+                     int success);
+int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks);
+void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted);
+void bitmap_close_sync(struct bitmap *bitmap);
+
+int bitmap_unplug(struct bitmap *bitmap);
+int bitmap_daemon_work(struct bitmap *bitmap);
+#endif
+
+#endif
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index bce0032decff..16e94a9f0f8c 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -267,6 +267,9 @@ struct mddev_s
         atomic_t                        writes_pending; 
         request_queue_t                 *queue; /* for plugging ... */
 
+        struct bitmap                   *bitmap; /* the bitmap for the device */
+        struct file                     *bitmap_file; /* the bitmap file */
+
         struct list_head                all_mddevs;
 };
 
@@ -341,6 +344,7 @@ typedef struct mdk_thread_s {
         unsigned long           flags;
         struct completion       *event;
         struct task_struct      *tsk;
+        unsigned long           timeout;
         const char              *name;
 } mdk_thread_t;
 
diff --git a/include/linux/raid/md_u.h b/include/linux/raid/md_u.h
index a2df5c2a42af..81da20ccec4d 100644
--- a/include/linux/raid/md_u.h
+++ b/include/linux/raid/md_u.h
@@ -23,6 +23,7 @@
 #define GET_DISK_INFO           _IOR (MD_MAJOR, 0x12, mdu_disk_info_t)
 #define PRINT_RAID_DEBUG        _IO (MD_MAJOR, 0x13)
 #define RAID_AUTORUN            _IO (MD_MAJOR, 0x14)
+#define GET_BITMAP_FILE         _IOR (MD_MAJOR, 0x15, mdu_bitmap_file_t)
 
 /* configuration */
 #define CLEAR_ARRAY             _IO (MD_MAJOR, 0x20)
@@ -36,6 +37,7 @@
 #define HOT_ADD_DISK            _IO (MD_MAJOR, 0x28)
 #define SET_DISK_FAULTY         _IO (MD_MAJOR, 0x29)
 #define HOT_GENERATE_ERROR      _IO (MD_MAJOR, 0x2a)
+#define SET_BITMAP_FILE         _IOW (MD_MAJOR, 0x2b, int)
 
 /* usage */
 #define RUN_ARRAY               _IOW (MD_MAJOR, 0x30, mdu_param_t)
@@ -106,6 +108,11 @@ typedef struct mdu_start_info_s {
 
 } mdu_start_info_t;
 
+typedef struct mdu_bitmap_file_s
+{
+        char pathname[4096];
+} mdu_bitmap_file_t;
+
 typedef struct mdu_param_s
 {
         int                     personality;    /* 1,2,3,4 */