1 files changed, 391 insertions, 58 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 60e2b322db11..26ac8aad0b19 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -212,7 +212,7 @@ static void bitmap_checkfree(struct bitmap *bitmap, unsigned long page)
  */
 
 /* IO operations when bitmap is stored near all superblocks */
-static struct page *read_sb_page(mddev_t *mddev, long offset,
+static struct page *read_sb_page(mddev_t *mddev, loff_t offset,
                                  struct page *page,
                                  unsigned long index, int size)
 {
@@ -287,27 +287,36 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 
         while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
                         int size = PAGE_SIZE;
+                        loff_t offset = mddev->bitmap_info.offset;
                         if (page->index == bitmap->file_pages-1)
                                 size = roundup(bitmap->last_page_size,
                                                bdev_logical_block_size(rdev->bdev));
                         /* Just make sure we aren't corrupting data or
                          * metadata
                          */
-                        if (bitmap->offset < 0) {
+                        if (mddev->external) {
+                                /* Bitmap could be anywhere. */
+                                if (rdev->sb_start + offset + (page->index *(PAGE_SIZE/512)) >
+                                    rdev->data_offset &&
+                                    rdev->sb_start + offset < 
+                                    rdev->data_offset + mddev->dev_sectors +
+                                    (PAGE_SIZE/512))
+                                        goto bad_alignment;
+                        } else if (offset < 0) {
                                 /* DATA  BITMAP METADATA  */
-                                if (bitmap->offset
+                                if (offset
                                     + (long)(page->index * (PAGE_SIZE/512))
                                     + size/512 > 0)
                                         /* bitmap runs in to metadata */
                                         goto bad_alignment;
                                 if (rdev->data_offset + mddev->dev_sectors
-                                    > rdev->sb_start + bitmap->offset)
+                                    > rdev->sb_start + offset)
                                         /* data runs in to bitmap */
                                         goto bad_alignment;
                         } else if (rdev->sb_start < rdev->data_offset) {
                                 /* METADATA BITMAP DATA */
                                 if (rdev->sb_start
-                                    + bitmap->offset
+                                    + offset
                                     + page->index*(PAGE_SIZE/512) + size/512
                                     > rdev->data_offset)
                                         /* bitmap runs in to data */
@@ -316,7 +325,7 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
                                 /* DATA METADATA BITMAP - no problems */
                         }
                         md_super_write(mddev, rdev,
-                                       rdev->sb_start + bitmap->offset
+                                       rdev->sb_start + offset
                                        + page->index * (PAGE_SIZE/512),
                                        size,
                                        page);
@@ -488,6 +497,8 @@ void bitmap_update_sb(struct bitmap *bitmap)
 
         if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
                 return;
+        if (bitmap->mddev->bitmap_info.external)
+                return;
         spin_lock_irqsave(&bitmap->lock, flags);
         if (!bitmap->sb_page) { /* no superblock */
                 spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -501,6 +512,9 @@ void bitmap_update_sb(struct bitmap *bitmap)
                 bitmap->events_cleared = bitmap->mddev->events;
                 sb->events_cleared = cpu_to_le64(bitmap->events_cleared);
         }
+        /* Just in case these have been changed via sysfs: */
+        sb->daemon_sleep = cpu_to_le32(bitmap->mddev->bitmap_info.daemon_sleep/HZ);
+        sb->write_behind = cpu_to_le32(bitmap->mddev->bitmap_info.max_write_behind);
         kunmap_atomic(sb, KM_USER0);
         write_page(bitmap, bitmap->sb_page, 1);
 }
@@ -550,7 +564,8 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 
                 bitmap->sb_page = read_page(bitmap->file, 0, bitmap, bytes);
         } else {
-                bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset,
+                bitmap->sb_page = read_sb_page(bitmap->mddev,
+                                               bitmap->mddev->bitmap_info.offset,
                                                NULL,
                                                0, sizeof(bitmap_super_t));
         }
@@ -563,7 +578,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 
         chunksize = le32_to_cpu(sb->chunksize);
-        daemon_sleep = le32_to_cpu(sb->daemon_sleep);
+        daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
         write_behind = le32_to_cpu(sb->write_behind);
 
         /* verify that the bitmap-specific fields are valid */
@@ -576,7 +591,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
                 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 > MAX_SCHEDULE_TIMEOUT / HZ)
+        else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT)
                 reason = "daemon sleep period out of range";
         else if (write_behind > COUNTER_MAX)
                 reason = "write-behind limit out of range (0 - 16383)";
@@ -610,10 +625,9 @@ static int bitmap_read_sb(struct bitmap *bitmap)
         }
 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->mddev->bitmap_info.chunksize = chunksize;
+        bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
+        bitmap->mddev->bitmap_info.max_write_behind = write_behind;
         bitmap->flags |= le32_to_cpu(sb->state);
         if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
                 bitmap->flags |= BITMAP_HOSTENDIAN;
@@ -664,16 +678,26 @@ static int bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
  * general bitmap file operations
  */
 
+/*
+ * 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.
+ */
 /* calculate the index of the page that contains this bit */
-static inline unsigned long file_page_index(unsigned long chunk)
+static inline unsigned long file_page_index(struct bitmap *bitmap, unsigned long chunk)
 {
-        return CHUNK_BIT_OFFSET(chunk) >> PAGE_BIT_SHIFT;
+        if (!bitmap->mddev->bitmap_info.external)
+                chunk += sizeof(bitmap_super_t) << 3;
+        return chunk >> PAGE_BIT_SHIFT;
 }
 
 /* calculate the (bit) offset of this bit within a page */
-static inline unsigned long file_page_offset(unsigned long chunk)
+static inline unsigned long file_page_offset(struct bitmap *bitmap, unsigned long chunk)
 {
-        return CHUNK_BIT_OFFSET(chunk) & (PAGE_BITS - 1);
+        if (!bitmap->mddev->bitmap_info.external)
+                chunk += sizeof(bitmap_super_t) << 3;
+        return chunk & (PAGE_BITS - 1);
 }
 
 /*
@@ -686,8 +710,9 @@ static inline unsigned long file_page_offset(unsigned long chunk)
 static inline struct page *filemap_get_page(struct bitmap *bitmap,
                                         unsigned long chunk)
 {
-        if (file_page_index(chunk) >= bitmap->file_pages) return NULL;
-        return bitmap->filemap[file_page_index(chunk) - file_page_index(0)];
+        if (file_page_index(bitmap, chunk) >= bitmap->file_pages) return NULL;
+        return bitmap->filemap[file_page_index(bitmap, chunk)
+                               - file_page_index(bitmap, 0)];
 }
 
 
@@ -710,7 +735,7 @@ static void bitmap_file_unmap(struct bitmap *bitmap)
         spin_unlock_irqrestore(&bitmap->lock, flags);
 
         while (pages--)
-                if (map[pages]->index != 0) /* 0 is sb_page, release it below */
+                if (map[pages] != sb_page) /* 0 is sb_page, release it below */
                         free_buffers(map[pages]);
         kfree(map);
         kfree(attr);
@@ -821,7 +846,7 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
 
         page = filemap_get_page(bitmap, chunk);
         if (!page) return;
-        bit = file_page_offset(chunk);
+        bit = file_page_offset(bitmap, chunk);
 
         /* set the bit */
         kaddr = kmap_atomic(page, KM_USER0);
@@ -907,7 +932,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
         chunks = bitmap->chunks;
         file = bitmap->file;
 
-        BUG_ON(!file && !bitmap->offset);
+        BUG_ON(!file && !bitmap->mddev->bitmap_info.offset);
 
 #ifdef INJECT_FAULTS_3
         outofdate = 1;
@@ -919,14 +944,17 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
                         "recovery\n", bmname(bitmap));
 
         bytes = (chunks + 7) / 8;
+        if (!bitmap->mddev->bitmap_info.external)
+                bytes += sizeof(bitmap_super_t);
 
-        num_pages = (bytes + sizeof(bitmap_super_t) + PAGE_SIZE - 1) / PAGE_SIZE;
+        
+        num_pages = (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
 
-        if (file && i_size_read(file->f_mapping->host) < bytes + sizeof(bitmap_super_t)) {
+        if (file && i_size_read(file->f_mapping->host) < bytes) {
                 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));
+                        bytes);
                 goto err;
         }
 
@@ -947,17 +975,16 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 
         for (i = 0; i < chunks; i++) {
                 int b;
-                index = file_page_index(i);
-                bit = file_page_offset(i);
+                index = file_page_index(bitmap, i);
+                bit = file_page_offset(bitmap, i);
                 if (index != oldindex) { /* this is a new page, read it in */
                         int count;
                         /* unmap the old page, we're done with it */
                         if (index == num_pages-1)
-                                count = bytes + sizeof(bitmap_super_t)
-                                        - index * PAGE_SIZE;
+                                count = bytes - index * PAGE_SIZE;
                         else
                                 count = PAGE_SIZE;
-                        if (index == 0) {
+                        if (index == 0 && bitmap->sb_page) {
                                 /*
                                  * if we're here then the superblock page
                                  * contains some bits (PAGE_SIZE != sizeof sb)
@@ -967,14 +994,15 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
                                 offset = sizeof(bitmap_super_t);
                                 if (!file)
                                         read_sb_page(bitmap->mddev,
-                                                     bitmap->offset,
+                                                     bitmap->mddev->bitmap_info.offset,
                                                      page,
                                                      index, count);
                         } else if (file) {
                                 page = read_page(file, index, bitmap, count);
                                 offset = 0;
                         } else {
-                                page = read_sb_page(bitmap->mddev, bitmap->offset,
+                                page = read_sb_page(bitmap->mddev,
+                                                    bitmap->mddev->bitmap_info.offset,
                                                     NULL,
                                                     index, count);
                                 offset = 0;
@@ -1078,23 +1106,32 @@ static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
  *                      out to disk
  */
 
-void bitmap_daemon_work(struct bitmap *bitmap)
+void bitmap_daemon_work(mddev_t *mddev)
 {
+        struct bitmap *bitmap;
         unsigned long j;
         unsigned long flags;
         struct page *page = NULL, *lastpage = NULL;
         int blocks;
         void *paddr;
 
-        if (bitmap == NULL)
+        /* Use a mutex to guard daemon_work against
+         * bitmap_destroy.
+         */
+        mutex_lock(&mddev->bitmap_info.mutex);
+        bitmap = mddev->bitmap;
+        if (bitmap == NULL) {
+                mutex_unlock(&mddev->bitmap_info.mutex);
                 return;
-        if (time_before(jiffies, bitmap->daemon_lastrun + bitmap->daemon_sleep*HZ))
+        }
+        if (time_before(jiffies, bitmap->daemon_lastrun
+                        + bitmap->mddev->bitmap_info.daemon_sleep))
                 goto done;
 
         bitmap->daemon_lastrun = jiffies;
         if (bitmap->allclean) {
                 bitmap->mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
-                return;
+                goto done;
         }
         bitmap->allclean = 1;
 
@@ -1142,7 +1179,8 @@ void bitmap_daemon_work(struct bitmap *bitmap)
                         /* We are possibly going to clear some bits, so make
                          * sure that events_cleared is up-to-date.
                          */
-                        if (bitmap->need_sync) {
+                        if (bitmap->need_sync &&
+                            bitmap->mddev->bitmap_info.external == 0) {
                                 bitmap_super_t *sb;
                                 bitmap->need_sync = 0;
                                 sb = kmap_atomic(bitmap->sb_page, KM_USER0);
@@ -1152,7 +1190,8 @@ void bitmap_daemon_work(struct bitmap *bitmap)
                                 write_page(bitmap, bitmap->sb_page, 1);
                         }
                         spin_lock_irqsave(&bitmap->lock, flags);
-                        clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
+                        if (!bitmap->need_sync)
+                                clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
                 }
                 bmc = bitmap_get_counter(bitmap,
                                          (sector_t)j << CHUNK_BLOCK_SHIFT(bitmap),
@@ -1167,7 +1206,7 @@ void bitmap_daemon_work(struct bitmap *bitmap)
                         if (*bmc == 2) {
                                 *bmc=1; /* maybe clear the bit next time */
                                 set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
-                        } else if (*bmc == 1) {
+                        } else if (*bmc == 1 && !bitmap->need_sync) {
                                 /* we can clear the bit */
                                 *bmc = 0;
                                 bitmap_count_page(bitmap,
@@ -1177,9 +1216,11 @@ void bitmap_daemon_work(struct bitmap *bitmap)
                                 /* clear the bit */
                                 paddr = kmap_atomic(page, KM_USER0);
                                 if (bitmap->flags & BITMAP_HOSTENDIAN)
-                                        clear_bit(file_page_offset(j), paddr);
+                                        clear_bit(file_page_offset(bitmap, j),
+                                                  paddr);
                                 else
-                                        ext2_clear_bit(file_page_offset(j), paddr);
+                                        ext2_clear_bit(file_page_offset(bitmap, j),
+                                                       paddr);
                                 kunmap_atomic(paddr, KM_USER0);
                         }
                 } else
@@ -1202,7 +1243,9 @@ void bitmap_daemon_work(struct bitmap *bitmap)
 
  done:
         if (bitmap->allclean == 0)
-                bitmap->mddev->thread->timeout = bitmap->daemon_sleep * HZ;
+                bitmap->mddev->thread->timeout = 
+                        bitmap->mddev->bitmap_info.daemon_sleep;
+        mutex_unlock(&mddev->bitmap_info.mutex);
 }
 
 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
@@ -1332,6 +1375,7 @@ void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long secto
                     bitmap->events_cleared < bitmap->mddev->events) {
                         bitmap->events_cleared = bitmap->mddev->events;
                         bitmap->need_sync = 1;
+                        sysfs_notify_dirent(bitmap->sysfs_can_clear);
                 }
 
                 if (!success && ! (*bmc & NEEDED_MASK))
@@ -1470,7 +1514,7 @@ void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector)
                 return;
         }
         if (time_before(jiffies, (bitmap->last_end_sync
-                                  + bitmap->daemon_sleep * HZ)))
+                                  + bitmap->mddev->bitmap_info.daemon_sleep)))
                 return;
         wait_event(bitmap->mddev->recovery_wait,
                    atomic_read(&bitmap->mddev->recovery_active) == 0);
@@ -1522,6 +1566,12 @@ void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e)
                 sector_t sec = (sector_t)chunk << CHUNK_BLOCK_SHIFT(bitmap);
                 bitmap_set_memory_bits(bitmap, sec, 1);
                 bitmap_file_set_bit(bitmap, sec);
+                if (sec < bitmap->mddev->recovery_cp)
+                        /* We are asserting that the array is dirty,
+                         * so move the recovery_cp address back so
+                         * that it is obvious that it is dirty
+                         */
+                        bitmap->mddev->recovery_cp = sec;
         }
 }
 
@@ -1531,7 +1581,7 @@ void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e)
 void bitmap_flush(mddev_t *mddev)
 {
         struct bitmap *bitmap = mddev->bitmap;
-        int sleep;
+        long sleep;
 
         if (!bitmap) /* there was no bitmap */
                 return;
@@ -1539,12 +1589,13 @@ void bitmap_flush(mddev_t *mddev)
         /* 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;
+        sleep = mddev->bitmap_info.daemon_sleep * 2;
+        bitmap->daemon_lastrun -= sleep;
+        bitmap_daemon_work(mddev);
+        bitmap->daemon_lastrun -= sleep;
+        bitmap_daemon_work(mddev);
+        bitmap->daemon_lastrun -= sleep;
+        bitmap_daemon_work(mddev);
         bitmap_update_sb(bitmap);
 }
 
@@ -1574,6 +1625,7 @@ static void bitmap_free(struct bitmap *bitmap)
         kfree(bp);
         kfree(bitmap);
 }
+
 void bitmap_destroy(mddev_t *mddev)
 {
         struct bitmap *bitmap = mddev->bitmap;
@@ -1581,10 +1633,15 @@ void bitmap_destroy(mddev_t *mddev)
         if (!bitmap) /* there was no bitmap */
                 return;
 
+        mutex_lock(&mddev->bitmap_info.mutex);
         mddev->bitmap = NULL; /* disconnect from the md device */
+        mutex_unlock(&mddev->bitmap_info.mutex);
         if (mddev->thread)
                 mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
 
+        if (bitmap->sysfs_can_clear)
+                sysfs_put(bitmap->sysfs_can_clear);
+
         bitmap_free(bitmap);
 }
 
@@ -1598,16 +1655,17 @@ int bitmap_create(mddev_t *mddev)
         sector_t blocks = mddev->resync_max_sectors;
         unsigned long chunks;
         unsigned long pages;
-        struct file *file = mddev->bitmap_file;
+        struct file *file = mddev->bitmap_info.file;
         int err;
         sector_t start;
+        struct sysfs_dirent *bm;
 
         BUILD_BUG_ON(sizeof(bitmap_super_t) != 256);
 
-        if (!file && !mddev->bitmap_offset) /* bitmap disabled, nothing to do */
+        if (!file && !mddev->bitmap_info.offset) /* bitmap disabled, nothing to do */
                 return 0;
 
-        BUG_ON(file && mddev->bitmap_offset);
+        BUG_ON(file && mddev->bitmap_info.offset);
 
         bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
         if (!bitmap)
@@ -1620,8 +1678,14 @@ int bitmap_create(mddev_t *mddev)
 
         bitmap->mddev = mddev;
 
+        bm = sysfs_get_dirent(mddev->kobj.sd, "bitmap");
+        if (bm) {
+                bitmap->sysfs_can_clear = sysfs_get_dirent(bm, "can_clear");
+                sysfs_put(bm);
+        } else
+                bitmap->sysfs_can_clear = NULL;
+
         bitmap->file = file;
-        bitmap->offset = mddev->bitmap_offset;
         if (file) {
                 get_file(file);
                 /* As future accesses to this file will use bmap,
@@ -1630,12 +1694,22 @@ int bitmap_create(mddev_t *mddev)
                  */
                 vfs_fsync(file, file->f_dentry, 1);
         }
-        /* read superblock from bitmap file (this sets bitmap->chunksize) */
-        err = bitmap_read_sb(bitmap);
+        /* read superblock from bitmap file (this sets mddev->bitmap_info.chunksize) */
+        if (!mddev->bitmap_info.external)
+                err = bitmap_read_sb(bitmap);
+        else {
+                err = 0;
+                if (mddev->bitmap_info.chunksize == 0 ||
+                    mddev->bitmap_info.daemon_sleep == 0)
+                        /* chunksize and time_base need to be
+                         * set first. */
+                        err = -EINVAL;
+        }
         if (err)
                 goto error;
 
-        bitmap->chunkshift = ffz(~bitmap->chunksize);
+        bitmap->daemon_lastrun = jiffies;
+        bitmap->chunkshift = ffz(~mddev->bitmap_info.chunksize);
 
         /* now that chunksize and chunkshift are set, we can use these macros */
         chunks = (blocks + CHUNK_BLOCK_RATIO(bitmap) - 1) >>
@@ -1677,7 +1751,8 @@ int bitmap_create(mddev_t *mddev)
 
         mddev->bitmap = bitmap;
 
-        mddev->thread->timeout = bitmap->daemon_sleep * HZ;
+        mddev->thread->timeout = mddev->bitmap_info.daemon_sleep;
+        md_wakeup_thread(mddev->thread);
 
         bitmap_update_sb(bitmap);
 
@@ -1688,6 +1763,264 @@ int bitmap_create(mddev_t *mddev)
         return err;
 }
 
+static ssize_t
+location_show(mddev_t *mddev, char *page)
+{
+        ssize_t len;
+        if (mddev->bitmap_info.file) {
+                len = sprintf(page, "file");
+        } else if (mddev->bitmap_info.offset) {
+                len = sprintf(page, "%+lld", (long long)mddev->bitmap_info.offset);
+        } else
+                len = sprintf(page, "none");
+        len += sprintf(page+len, "\n");
+        return len;
+}
+
+static ssize_t
+location_store(mddev_t *mddev, const char *buf, size_t len)
+{
+
+        if (mddev->pers) {
+                if (!mddev->pers->quiesce)
+                        return -EBUSY;
+                if (mddev->recovery || mddev->sync_thread)
+                        return -EBUSY;
+        }
+
+        if (mddev->bitmap || mddev->bitmap_info.file ||
+            mddev->bitmap_info.offset) {
+                /* bitmap already configured.  Only option is to clear it */
+                if (strncmp(buf, "none", 4) != 0)
+                        return -EBUSY;
+                if (mddev->pers) {
+                        mddev->pers->quiesce(mddev, 1);
+                        bitmap_destroy(mddev);
+                        mddev->pers->quiesce(mddev, 0);
+                }
+                mddev->bitmap_info.offset = 0;
+                if (mddev->bitmap_info.file) {
+                        struct file *f = mddev->bitmap_info.file;
+                        mddev->bitmap_info.file = NULL;
+                        restore_bitmap_write_access(f);
+                        fput(f);
+                }
+        } else {
+                /* No bitmap, OK to set a location */
+                long long offset;
+                if (strncmp(buf, "none", 4) == 0)
+                        /* nothing to be done */;
+                else if (strncmp(buf, "file:", 5) == 0) {
+                        /* Not supported yet */
+                        return -EINVAL;
+                } else {
+                        int rv;
+                        if (buf[0] == '+')
+                                rv = strict_strtoll(buf+1, 10, &offset);
+                        else
+                                rv = strict_strtoll(buf, 10, &offset);
+                        if (rv)
+                                return rv;
+                        if (offset == 0)
+                                return -EINVAL;
+                        if (mddev->bitmap_info.external == 0 &&
+                            mddev->major_version == 0 &&
+                            offset != mddev->bitmap_info.default_offset)
+                                return -EINVAL;
+                        mddev->bitmap_info.offset = offset;
+                        if (mddev->pers) {
+                                mddev->pers->quiesce(mddev, 1);
+                                rv = bitmap_create(mddev);
+                                if (rv) {
+                                        bitmap_destroy(mddev);
+                                        mddev->bitmap_info.offset = 0;
+                                }
+                                mddev->pers->quiesce(mddev, 0);
+                                if (rv)
+                                        return rv;
+                        }
+                }
+        }
+        if (!mddev->external) {
+                /* Ensure new bitmap info is stored in
+                 * metadata promptly.
+                 */
+                set_bit(MD_CHANGE_DEVS, &mddev->flags);
+                md_wakeup_thread(mddev->thread);
+        }
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_location =
+__ATTR(location, S_IRUGO|S_IWUSR, location_show, location_store);
+
+static ssize_t
+timeout_show(mddev_t *mddev, char *page)
+{
+        ssize_t len;
+        unsigned long secs = mddev->bitmap_info.daemon_sleep / HZ;
+        unsigned long jifs = mddev->bitmap_info.daemon_sleep % HZ;
+        
+        len = sprintf(page, "%lu", secs);
+        if (jifs)
+                len += sprintf(page+len, ".%03u", jiffies_to_msecs(jifs));
+        len += sprintf(page+len, "\n");
+        return len;
+}
+
+static ssize_t
+timeout_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        /* timeout can be set at any time */
+        unsigned long timeout;
+        int rv = strict_strtoul_scaled(buf, &timeout, 4);
+        if (rv)
+                return rv;
+
+        /* just to make sure we don't overflow... */
+        if (timeout >= LONG_MAX / HZ)
+                return -EINVAL;
+
+        timeout = timeout * HZ / 10000;
+
+        if (timeout >= MAX_SCHEDULE_TIMEOUT)
+                timeout = MAX_SCHEDULE_TIMEOUT-1;
+        if (timeout < 1)
+                timeout = 1;
+        mddev->bitmap_info.daemon_sleep = timeout;
+        if (mddev->thread) {
+                /* if thread->timeout is MAX_SCHEDULE_TIMEOUT, then
+                 * the bitmap is all clean and we don't need to
+                 * adjust the timeout right now
+                 */
+                if (mddev->thread->timeout < MAX_SCHEDULE_TIMEOUT) {
+                        mddev->thread->timeout = timeout;
+                        md_wakeup_thread(mddev->thread);
+                }
+        }
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_timeout =
+__ATTR(time_base, S_IRUGO|S_IWUSR, timeout_show, timeout_store);
+
+static ssize_t
+backlog_show(mddev_t *mddev, char *page)
+{
+        return sprintf(page, "%lu\n", mddev->bitmap_info.max_write_behind);
+}
+
+static ssize_t
+backlog_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        unsigned long backlog;
+        int rv = strict_strtoul(buf, 10, &backlog);
+        if (rv)
+                return rv;
+        if (backlog > COUNTER_MAX)
+                return -EINVAL;
+        mddev->bitmap_info.max_write_behind = backlog;
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_backlog =
+__ATTR(backlog, S_IRUGO|S_IWUSR, backlog_show, backlog_store);
+
+static ssize_t
+chunksize_show(mddev_t *mddev, char *page)
+{
+        return sprintf(page, "%lu\n", mddev->bitmap_info.chunksize);
+}
+
+static ssize_t
+chunksize_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        /* Can only be changed when no bitmap is active */
+        int rv;
+        unsigned long csize;
+        if (mddev->bitmap)
+                return -EBUSY;
+        rv = strict_strtoul(buf, 10, &csize);
+        if (rv)
+                return rv;
+        if (csize < 512 ||
+            !is_power_of_2(csize))
+                return -EINVAL;
+        mddev->bitmap_info.chunksize = csize;
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_chunksize =
+__ATTR(chunksize, S_IRUGO|S_IWUSR, chunksize_show, chunksize_store);
+
+static ssize_t metadata_show(mddev_t *mddev, char *page)
+{
+        return sprintf(page, "%s\n", (mddev->bitmap_info.external
+                                      ? "external" : "internal"));
+}
+
+static ssize_t metadata_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        if (mddev->bitmap ||
+            mddev->bitmap_info.file ||
+            mddev->bitmap_info.offset)
+                return -EBUSY;
+        if (strncmp(buf, "external", 8) == 0)
+                mddev->bitmap_info.external = 1;
+        else if (strncmp(buf, "internal", 8) == 0)
+                mddev->bitmap_info.external = 0;
+        else
+                return -EINVAL;
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_metadata =
+__ATTR(metadata, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
+
+static ssize_t can_clear_show(mddev_t *mddev, char *page)
+{
+        int len;
+        if (mddev->bitmap)
+                len = sprintf(page, "%s\n", (mddev->bitmap->need_sync ?
+                                             "false" : "true"));
+        else
+                len = sprintf(page, "\n");
+        return len;
+}
+
+static ssize_t can_clear_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        if (mddev->bitmap == NULL)
+                return -ENOENT;
+        if (strncmp(buf, "false", 5) == 0)
+                mddev->bitmap->need_sync = 1;
+        else if (strncmp(buf, "true", 4) == 0) {
+                if (mddev->degraded)
+                        return -EBUSY;
+                mddev->bitmap->need_sync = 0;
+        } else
+                return -EINVAL;
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_can_clear =
+__ATTR(can_clear, S_IRUGO|S_IWUSR, can_clear_show, can_clear_store);
+
+static struct attribute *md_bitmap_attrs[] = {
+        &bitmap_location.attr,
+        &bitmap_timeout.attr,
+        &bitmap_backlog.attr,
+        &bitmap_chunksize.attr,
+        &bitmap_metadata.attr,
+        &bitmap_can_clear.attr,
+        NULL
+};
+struct attribute_group md_bitmap_group = {
+        .name = "bitmap",
+        .attrs = md_bitmap_attrs,
+};
+
+
 /* the bitmap API -- for raid personalities */
 EXPORT_SYMBOL(bitmap_startwrite);
 EXPORT_SYMBOL(bitmap_endwrite);