// SPDX-License-Identifier: GPL-2.0-only

  /*
   * 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

   */
  
  /*
   * Still to do:
   *
   * flush after percent set rather than just time based. (maybe both).

   */

  #include <linux/blkdev.h>

  #include <linux/module.h>

  #include <linux/errno.h>
  #include <linux/slab.h>
  #include <linux/init.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/seq_file.h>

  #include <trace/events/block.h>

  #include "md.h"

  #include "md-bitmap.h"

  static inline char *bmname(struct bitmap *bitmap)

  {
  	return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
  }

  /*

   * 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 md_bitmap_checkpage(struct bitmap_counts *bitmap,
  			       unsigned long page, int create, int no_hijack)

  __releases(bitmap->lock)
  __acquires(bitmap->lock)

  {
  	unsigned char *mappage;
  
  	if (page >= bitmap->pages) {

  		/* This can happen if bitmap_start_sync goes beyond
  		 * End-of-device while looking for a whole page.
  		 * It is harmless.
  		 */

  		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;

  	/* this page has not been allocated yet */

  	spin_unlock_irq(&bitmap->lock);

  	/* It is possible that this is being called inside a
  	 * prepare_to_wait/finish_wait loop from raid5c:make_request().
  	 * In general it is not permitted to sleep in that context as it
  	 * can cause the loop to spin freely.
  	 * That doesn't apply here as we can only reach this point
  	 * once with any loop.
  	 * When this function completes, either bp[page].map or
  	 * bp[page].hijacked.  In either case, this function will
  	 * abort before getting to this point again.  So there is
  	 * no risk of a free-spin, and so it is safe to assert
  	 * that sleeping here is allowed.
  	 */
  	sched_annotate_sleep();

  	mappage = kzalloc(PAGE_SIZE, GFP_NOIO);

  	spin_lock_irq(&bitmap->lock);
  
  	if (mappage == NULL) {

  		pr_debug("md/bitmap: map page allocation failed, hijacking
  ");

  		/* We don't support hijack for cluster raid */
  		if (no_hijack)
  			return -ENOMEM;

  		/* failed - set the hijacked flag so that we can use the
  		 * pointer as a counter */

  		if (!bitmap->bp[page].map)
  			bitmap->bp[page].hijacked = 1;

  	} else if (bitmap->bp[page].map ||
  		   bitmap->bp[page].hijacked) {

  		/* somebody beat us to getting the page */

  		kfree(mappage);

  	} else {

  		/* no page was in place and we have one, so install it */

  		bitmap->bp[page].map = mappage;
  		bitmap->missing_pages--;
  	}

  	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 void md_bitmap_checkfree(struct bitmap_counts *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;

  	} else {
  		/* normal case, free the page */
  		ptr = bitmap->bp[page].map;
  		bitmap->bp[page].map = NULL;
  		bitmap->missing_pages++;

  		kfree(ptr);

  	}

  }

  /*
   * bitmap file handling - read and write the bitmap file and its superblock
   */

  /*
   * basic page I/O operations
   */

  /* IO operations when bitmap is stored near all superblocks */

  static int read_sb_page(struct mddev *mddev, loff_t offset,
  			struct page *page,
  			unsigned long index, int size)

  {
  	/* choose a good rdev and read the page from there */

  	struct md_rdev *rdev;

  	sector_t target;

  	rdev_for_each(rdev, mddev) {

  		if (! test_bit(In_sync, &rdev->flags)

  		    || test_bit(Faulty, &rdev->flags)
  		    || test_bit(Bitmap_sync, &rdev->flags))

  			continue;

  		target = offset + index * (PAGE_SIZE/512);

  		if (sync_page_io(rdev, target,

  				 roundup(size, bdev_logical_block_size(rdev->bdev)),

  				 page, REQ_OP_READ, 0, true)) {

  			page->index = index;

  			return 0;

  		}
  	}

  	return -EIO;

  }

  static struct md_rdev *next_active_rdev(struct md_rdev *rdev, struct mddev *mddev)

  {
  	/* Iterate the disks of an mddev, using rcu to protect access to the
  	 * linked list, and raising the refcount of devices we return to ensure
  	 * they don't disappear while in use.
  	 * As devices are only added or removed when raid_disk is < 0 and
  	 * nr_pending is 0 and In_sync is clear, the entries we return will
  	 * still be in the same position on the list when we re-enter

  	 * list_for_each_entry_continue_rcu.

  	 *
  	 * Note that if entered with 'rdev == NULL' to start at the
  	 * beginning, we temporarily assign 'rdev' to an address which
  	 * isn't really an rdev, but which can be used by
  	 * list_for_each_entry_continue_rcu() to find the first entry.

  	 */

  	rcu_read_lock();
  	if (rdev == NULL)
  		/* start at the beginning */

  		rdev = list_entry(&mddev->disks, struct md_rdev, same_set);

  	else {
  		/* release the previous rdev and start from there. */
  		rdev_dec_pending(rdev, mddev);

  	}

  	list_for_each_entry_continue_rcu(rdev, &mddev->disks, same_set) {

  		if (rdev->raid_disk >= 0 &&

  		    !test_bit(Faulty, &rdev->flags)) {
  			/* this is a usable devices */
  			atomic_inc(&rdev->nr_pending);
  			rcu_read_unlock();
  			return rdev;
  		}
  	}
  	rcu_read_unlock();
  	return NULL;
  }

  static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)

  {

  	struct md_rdev *rdev;

  	struct block_device *bdev;

  	struct mddev *mddev = bitmap->mddev;

  	struct bitmap_storage *store = &bitmap->storage;

  restart:
  	rdev = NULL;

  	while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {

  		int size = PAGE_SIZE;
  		loff_t offset = mddev->bitmap_info.offset;

  
  		bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;

  		if (page->index == store->file_pages-1) {
  			int last_page_size = store->bytes & (PAGE_SIZE-1);
  			if (last_page_size == 0)
  				last_page_size = PAGE_SIZE;
  			size = roundup(last_page_size,

  				       bdev_logical_block_size(bdev));

  		}

  		/* Just make sure we aren't corrupting data or
  		 * metadata
  		 */
  		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 (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 + offset)
  				/* data runs in to bitmap */
  				goto bad_alignment;
  		} else if (rdev->sb_start < rdev->data_offset) {
  			/* METADATA BITMAP DATA */
  			if (rdev->sb_start
  			    + offset
  			    + page->index*(PAGE_SIZE/512) + size/512
  			    > rdev->data_offset)
  				/* bitmap runs in to data */
  				goto bad_alignment;
  		} else {
  			/* DATA METADATA BITMAP - no problems */
  		}
  		md_super_write(mddev, rdev,
  			       rdev->sb_start + offset
  			       + page->index * (PAGE_SIZE/512),
  			       size,
  			       page);

  	}

  	if (wait && md_super_wait(mddev) < 0)
  		goto restart;

  	return 0;

  
   bad_alignment:

  	return -EINVAL;

  }

  static void md_bitmap_file_kick(struct bitmap *bitmap);

  /*

   * write out a page to a file

   */

  static void write_page(struct bitmap *bitmap, struct page *page, int wait)

  {

  	struct buffer_head *bh;

  	if (bitmap->storage.file == NULL) {

  		switch (write_sb_page(bitmap, page, wait)) {
  		case -EINVAL:

  			set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);

  		}

  	} else {

  		bh = page_buffers(page);

  		while (bh && bh->b_blocknr) {
  			atomic_inc(&bitmap->pending_writes);
  			set_buffer_locked(bh);
  			set_buffer_mapped(bh);

  			submit_bh(REQ_OP_WRITE, REQ_SYNC, bh);

  			bh = bh->b_this_page;
  		}

  		if (wait)

  			wait_event(bitmap->write_wait,
  				   atomic_read(&bitmap->pending_writes)==0);

  	}

  	if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))

  		md_bitmap_file_kick(bitmap);

  }
  
  static void end_bitmap_write(struct buffer_head *bh, int uptodate)
  {
  	struct bitmap *bitmap = bh->b_private;

  	if (!uptodate)
  		set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);

  	if (atomic_dec_and_test(&bitmap->pending_writes))
  		wake_up(&bitmap->write_wait);
  }

  static void free_buffers(struct page *page)
  {

  	struct buffer_head *bh;

  	if (!PagePrivate(page))
  		return;
  
  	bh = page_buffers(page);

  	while (bh) {
  		struct buffer_head *next = bh->b_this_page;
  		free_buffer_head(bh);
  		bh = next;

  	}

  	detach_page_private(page);

  	put_page(page);

  }

  /* read a page from a file.
   * We both read the page, and attach buffers to the page to record the
   * address of each block (using bmap).  These addresses will be used
   * to write the block later, completely bypassing the filesystem.
   * This usage is similar to how swap files are handled, and allows us
   * to write to a file with no concerns of memory allocation failing.
   */

  static int read_page(struct file *file, unsigned long index,
  		     struct bitmap *bitmap,
  		     unsigned long count,
  		     struct page *page)

  {

  	int ret = 0;

  	struct inode *inode = file_inode(file);

  	struct buffer_head *bh;

  	sector_t block, blk_cur;

  	unsigned long blocksize = i_blocksize(inode);

  	pr_debug("read bitmap file (%dB @ %llu)
  ", (int)PAGE_SIZE,
  		 (unsigned long long)index << PAGE_SHIFT);

  	bh = alloc_page_buffers(page, blocksize, false);

  	if (!bh) {

  		ret = -ENOMEM;

  		goto out;
  	}

  	attach_page_private(page, bh);

  	blk_cur = index << (PAGE_SHIFT - inode->i_blkbits);

  	while (bh) {

  		block = blk_cur;

  		if (count == 0)
  			bh->b_blocknr = 0;
  		else {

  			ret = bmap(inode, &block);
  			if (ret || !block) {

  				ret = -EINVAL;

  				bh->b_blocknr = 0;

  				goto out;
  			}

  
  			bh->b_blocknr = block;

  			bh->b_bdev = inode->i_sb->s_bdev;

  			if (count < blocksize)

  				count = 0;
  			else

  				count -= blocksize;

  
  			bh->b_end_io = end_bitmap_write;
  			bh->b_private = bitmap;

  			atomic_inc(&bitmap->pending_writes);
  			set_buffer_locked(bh);
  			set_buffer_mapped(bh);

  			submit_bh(REQ_OP_READ, 0, bh);

  		}

  		blk_cur++;

  		bh = bh->b_this_page;
  	}

  	page->index = index;

  
  	wait_event(bitmap->write_wait,
  		   atomic_read(&bitmap->pending_writes)==0);

  	if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))

  		ret = -EIO;

  out:

  	if (ret)

  		pr_err("md: bitmap read error: (%dB @ %llu): %d
  ",
  		       (int)PAGE_SIZE,
  		       (unsigned long long)index << PAGE_SHIFT,
  		       ret);

  	return ret;

  }
  
  /*
   * bitmap file superblock operations
   */

  /*

   * md_bitmap_wait_writes() should be called before writing any bitmap

   * blocks, to ensure previous writes, particularly from

   * md_bitmap_daemon_work(), have completed.

   */

  static void md_bitmap_wait_writes(struct bitmap *bitmap)

  {
  	if (bitmap->storage.file)
  		wait_event(bitmap->write_wait,
  			   atomic_read(&bitmap->pending_writes)==0);
  	else

  		/* Note that we ignore the return value.  The writes
  		 * might have failed, but that would just mean that
  		 * some bits which should be cleared haven't been,
  		 * which is safe.  The relevant bitmap blocks will
  		 * probably get written again, but there is no great
  		 * loss if they aren't.
  		 */

  		md_super_wait(bitmap->mddev);
  }

  /* update the event counter and sync the superblock to disk */

  void md_bitmap_update_sb(struct bitmap *bitmap)

  {
  	bitmap_super_t *sb;

  
  	if (!bitmap || !bitmap->mddev) /* no bitmap for this array */

  		return;

  	if (bitmap->mddev->bitmap_info.external)
  		return;

  	if (!bitmap->storage.sb_page) /* no superblock */

  		return;

  	sb = kmap_atomic(bitmap->storage.sb_page);

  	sb->events = cpu_to_le64(bitmap->mddev->events);

  	if (bitmap->mddev->events < bitmap->events_cleared)

  		/* rocking back to read-only */
  		bitmap->events_cleared = bitmap->mddev->events;

  	sb->events_cleared = cpu_to_le64(bitmap->events_cleared);

  	/*
  	 * clear BITMAP_WRITE_ERROR bit to protect against the case that
  	 * a bitmap write error occurred but the later writes succeeded.
  	 */
  	sb->state = cpu_to_le32(bitmap->flags & ~BIT(BITMAP_WRITE_ERROR));

  	/* 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);

  	/* This might have been changed by a reshape */
  	sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
  	sb->chunksize = cpu_to_le32(bitmap->mddev->bitmap_info.chunksize);

  	sb->nodes = cpu_to_le32(bitmap->mddev->bitmap_info.nodes);

  	sb->sectors_reserved = cpu_to_le32(bitmap->mddev->
  					   bitmap_info.space);

  	kunmap_atomic(sb);

  	write_page(bitmap, bitmap->storage.sb_page, 1);

  }

  EXPORT_SYMBOL(md_bitmap_update_sb);

  
  /* print out the bitmap file superblock */

  void md_bitmap_print_sb(struct bitmap *bitmap)

  {
  	bitmap_super_t *sb;

  	if (!bitmap || !bitmap->storage.sb_page)

  		return;

  	sb = kmap_atomic(bitmap->storage.sb_page);

  	pr_debug("%s: bitmap file superblock:
  ", bmname(bitmap));
  	pr_debug("         magic: %08x
  ", le32_to_cpu(sb->magic));
  	pr_debug("       version: %d
  ", le32_to_cpu(sb->version));
  	pr_debug("          uuid: %08x.%08x.%08x.%08x
  ",

  		 le32_to_cpu(*(__le32 *)(sb->uuid+0)),
  		 le32_to_cpu(*(__le32 *)(sb->uuid+4)),
  		 le32_to_cpu(*(__le32 *)(sb->uuid+8)),
  		 le32_to_cpu(*(__le32 *)(sb->uuid+12)));

  	pr_debug("        events: %llu
  ",
  		 (unsigned long long) le64_to_cpu(sb->events));
  	pr_debug("events cleared: %llu
  ",
  		 (unsigned long long) le64_to_cpu(sb->events_cleared));
  	pr_debug("         state: %08x
  ", le32_to_cpu(sb->state));
  	pr_debug("     chunksize: %d B
  ", le32_to_cpu(sb->chunksize));
  	pr_debug("  daemon sleep: %ds
  ", le32_to_cpu(sb->daemon_sleep));
  	pr_debug("     sync size: %llu KB
  ",
  		 (unsigned long long)le64_to_cpu(sb->sync_size)/2);
  	pr_debug("max write behind: %d
  ", le32_to_cpu(sb->write_behind));

  	kunmap_atomic(sb);

  }

  /*
   * bitmap_new_disk_sb
   * @bitmap
   *
   * This function is somewhat the reverse of bitmap_read_sb.  bitmap_read_sb
   * reads and verifies the on-disk bitmap superblock and populates bitmap_info.
   * This function verifies 'bitmap_info' and populates the on-disk bitmap
   * structure, which is to be written to disk.
   *
   * Returns: 0 on success, -Exxx on error
   */

  static int md_bitmap_new_disk_sb(struct bitmap *bitmap)

  {
  	bitmap_super_t *sb;
  	unsigned long chunksize, daemon_sleep, write_behind;

  	bitmap->storage.sb_page = alloc_page(GFP_KERNEL | __GFP_ZERO);

  	if (bitmap->storage.sb_page == NULL)
  		return -ENOMEM;

  	bitmap->storage.sb_page->index = 0;

  	sb = kmap_atomic(bitmap->storage.sb_page);

  
  	sb->magic = cpu_to_le32(BITMAP_MAGIC);
  	sb->version = cpu_to_le32(BITMAP_MAJOR_HI);
  
  	chunksize = bitmap->mddev->bitmap_info.chunksize;
  	BUG_ON(!chunksize);
  	if (!is_power_of_2(chunksize)) {

  		kunmap_atomic(sb);

  		pr_warn("bitmap chunksize not a power of 2
  ");

  		return -EINVAL;
  	}
  	sb->chunksize = cpu_to_le32(chunksize);
  
  	daemon_sleep = bitmap->mddev->bitmap_info.daemon_sleep;

  	if (!daemon_sleep || (daemon_sleep > MAX_SCHEDULE_TIMEOUT)) {

  		pr_debug("Choosing daemon_sleep default (5 sec)
  ");

  		daemon_sleep = 5 * HZ;
  	}
  	sb->daemon_sleep = cpu_to_le32(daemon_sleep);
  	bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
  
  	/*
  	 * FIXME: write_behind for RAID1.  If not specified, what
  	 * is a good choice?  We choose COUNTER_MAX / 2 arbitrarily.
  	 */
  	write_behind = bitmap->mddev->bitmap_info.max_write_behind;
  	if (write_behind > COUNTER_MAX)
  		write_behind = COUNTER_MAX / 2;
  	sb->write_behind = cpu_to_le32(write_behind);
  	bitmap->mddev->bitmap_info.max_write_behind = write_behind;
  
  	/* keep the array size field of the bitmap superblock up to date */
  	sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
  
  	memcpy(sb->uuid, bitmap->mddev->uuid, 16);

  	set_bit(BITMAP_STALE, &bitmap->flags);

  	sb->state = cpu_to_le32(bitmap->flags);

  	bitmap->events_cleared = bitmap->mddev->events;
  	sb->events_cleared = cpu_to_le64(bitmap->mddev->events);

  	bitmap->mddev->bitmap_info.nodes = 0;

  	kunmap_atomic(sb);

  
  	return 0;
  }

  /* read the superblock from the bitmap file and initialize some bitmap fields */

  static int md_bitmap_read_sb(struct bitmap *bitmap)

  {
  	char *reason = NULL;
  	bitmap_super_t *sb;

  	unsigned long chunksize, daemon_sleep, write_behind;

  	unsigned long long events;

  	int nodes = 0;

  	unsigned long sectors_reserved = 0;

  	int err = -EINVAL;

  	struct page *sb_page;

  	loff_t offset = bitmap->mddev->bitmap_info.offset;

  	if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {

  		chunksize = 128 * 1024 * 1024;
  		daemon_sleep = 5 * HZ;
  		write_behind = 0;

  		set_bit(BITMAP_STALE, &bitmap->flags);

  		err = 0;
  		goto out_no_sb;
  	}

  	/* page 0 is the superblock, read it... */

  	sb_page = alloc_page(GFP_KERNEL);
  	if (!sb_page)
  		return -ENOMEM;

  	bitmap->storage.sb_page = sb_page;

  re_read:

  	/* If cluster_slot is set, the cluster is setup */
  	if (bitmap->cluster_slot >= 0) {

  		sector_t bm_blocks = bitmap->mddev->resync_max_sectors;

  		bm_blocks = DIV_ROUND_UP_SECTOR_T(bm_blocks,
  			   (bitmap->mddev->bitmap_info.chunksize >> 9));

  		/* bits to bytes */
  		bm_blocks = ((bm_blocks+7) >> 3) + sizeof(bitmap_super_t);
  		/* to 4k blocks */

  		bm_blocks = DIV_ROUND_UP_SECTOR_T(bm_blocks, 4096);

  		offset = bitmap->mddev->bitmap_info.offset + (bitmap->cluster_slot * (bm_blocks << 3));

  		pr_debug("%s:%d bm slot: %d offset: %llu
  ", __func__, __LINE__,

  			bitmap->cluster_slot, offset);

  	}

  	if (bitmap->storage.file) {
  		loff_t isize = i_size_read(bitmap->storage.file->f_mapping->host);

  		int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;

  		err = read_page(bitmap->storage.file, 0,

  				bitmap, bytes, sb_page);

  	} else {

  		err = read_sb_page(bitmap->mddev,

  				   offset,

  				   sb_page,

  				   0, sizeof(bitmap_super_t));

  	}

  	if (err)

  		return err;

  	err = -EINVAL;

  	sb = kmap_atomic(sb_page);

  	chunksize = le32_to_cpu(sb->chunksize);

  	daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;

  	write_behind = le32_to_cpu(sb->write_behind);

  	sectors_reserved = le32_to_cpu(sb->sectors_reserved);

  	/* Setup nodes/clustername only if bitmap version is
  	 * cluster-compatible

  	 */

  	if (sb->version == cpu_to_le32(BITMAP_MAJOR_CLUSTERED)) {

  		nodes = le32_to_cpu(sb->nodes);
  		strlcpy(bitmap->mddev->bitmap_info.cluster_name,
  				sb->cluster_name, 64);
  	}

  
  	/* verify that the bitmap-specific fields are valid */
  	if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
  		reason = "bad magic";

  	else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||

  		 le32_to_cpu(sb->version) > BITMAP_MAJOR_CLUSTERED)

  		reason = "unrecognized superblock version";

  	else if (chunksize < 512)

  		reason = "bitmap chunksize too small";

  	else if (!is_power_of_2(chunksize))

  		reason = "bitmap chunksize not a power of 2";

  	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)";

  	if (reason) {

  		pr_warn("%s: invalid bitmap file superblock: %s
  ",

  			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) {
  		/*
  		 * We have a persistent array superblock, so compare the
  		 * bitmap's UUID and event counter to the mddev's
  		 */
  		if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {

  			pr_warn("%s: bitmap superblock UUID mismatch
  ",
  				bmname(bitmap));

  			goto out;
  		}
  		events = le64_to_cpu(sb->events);

  		if (!nodes && (events < bitmap->mddev->events)) {

  			pr_warn("%s: bitmap file is out of date (%llu < %llu) -- forcing full recovery
  ",
  				bmname(bitmap), events,
  				(unsigned long long) bitmap->mddev->events);

  			set_bit(BITMAP_STALE, &bitmap->flags);

  		}

  	}

  	/* assign fields using values from superblock */

  	bitmap->flags |= le32_to_cpu(sb->state);

  	if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)

  		set_bit(BITMAP_HOSTENDIAN, &bitmap->flags);

  	bitmap->events_cleared = le64_to_cpu(sb->events_cleared);

  	strlcpy(bitmap->mddev->bitmap_info.cluster_name, sb->cluster_name, 64);

  	err = 0;

  out:

  	kunmap_atomic(sb);

  	/* Assigning chunksize is required for "re_read" */

  	bitmap->mddev->bitmap_info.chunksize = chunksize;

  	if (err == 0 && nodes && (bitmap->cluster_slot < 0)) {

  		err = md_setup_cluster(bitmap->mddev, nodes);
  		if (err) {

  			pr_warn("%s: Could not setup cluster service (%d)
  ",
  				bmname(bitmap), err);

  			goto out_no_sb;
  		}
  		bitmap->cluster_slot = md_cluster_ops->slot_number(bitmap->mddev);

  		goto re_read;
  	}

  out_no_sb:

  	if (test_bit(BITMAP_STALE, &bitmap->flags))

  		bitmap->events_cleared = bitmap->mddev->events;
  	bitmap->mddev->bitmap_info.chunksize = chunksize;
  	bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
  	bitmap->mddev->bitmap_info.max_write_behind = write_behind;

  	bitmap->mddev->bitmap_info.nodes = nodes;

  	if (bitmap->mddev->bitmap_info.space == 0 ||
  	    bitmap->mddev->bitmap_info.space > sectors_reserved)
  		bitmap->mddev->bitmap_info.space = sectors_reserved;

  	if (err) {

  		md_bitmap_print_sb(bitmap);

  		if (bitmap->cluster_slot < 0)

  			md_cluster_stop(bitmap->mddev);
  	}

  	return err;
  }

  /*
   * 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(struct bitmap_storage *store,
  					    unsigned long chunk)

  {

  	if (store->sb_page)

  		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(struct bitmap_storage *store,
  					     unsigned long chunk)

  {

  	if (store->sb_page)

  		chunk += sizeof(bitmap_super_t) << 3;
  	return chunk & (PAGE_BITS - 1);

  }
  
  /*
   * return a pointer to the page in the filemap that contains the given bit
   *

   */

  static inline struct page *filemap_get_page(struct bitmap_storage *store,

  					    unsigned long chunk)

  {

  	if (file_page_index(store, chunk) >= store->file_pages)

  		return NULL;

  	return store->filemap[file_page_index(store, chunk)];

  }

  static int md_bitmap_storage_alloc(struct bitmap_storage *store,
  				   unsigned long chunks, int with_super,
  				   int slot_number)

  {

  	int pnum, offset = 0;

  	unsigned long num_pages;
  	unsigned long bytes;
  
  	bytes = DIV_ROUND_UP(chunks, 8);
  	if (with_super)
  		bytes += sizeof(bitmap_super_t);
  
  	num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);

  	offset = slot_number * num_pages;

  	store->filemap = kmalloc_array(num_pages, sizeof(struct page *),
  				       GFP_KERNEL);

  	if (!store->filemap)
  		return -ENOMEM;
  
  	if (with_super && !store->sb_page) {

  		store->sb_page = alloc_page(GFP_KERNEL|__GFP_ZERO);

  		if (store->sb_page == NULL)
  			return -ENOMEM;

  	}

  	pnum = 0;
  	if (store->sb_page) {
  		store->filemap[0] = store->sb_page;
  		pnum = 1;

  		store->sb_page->index = offset;

  	}

  	for ( ; pnum < num_pages; pnum++) {

  		store->filemap[pnum] = alloc_page(GFP_KERNEL|__GFP_ZERO);

  		if (!store->filemap[pnum]) {
  			store->file_pages = pnum;
  			return -ENOMEM;
  		}

  		store->filemap[pnum]->index = pnum + offset;

  	}
  	store->file_pages = pnum;
  
  	/* We need 4 bits per page, rounded up to a multiple
  	 * of sizeof(unsigned long) */
  	store->filemap_attr = kzalloc(
  		roundup(DIV_ROUND_UP(num_pages*4, 8), sizeof(unsigned long)),
  		GFP_KERNEL);
  	if (!store->filemap_attr)
  		return -ENOMEM;
  
  	store->bytes = bytes;
  
  	return 0;
  }

  static void md_bitmap_file_unmap(struct bitmap_storage *store)

  {
  	struct page **map, *sb_page;

  	int pages;

  	struct file *file;

  	file = store->file;

  	map = store->filemap;

  	pages = store->file_pages;

  	sb_page = store->sb_page;

  
  	while (pages--)

  		if (map[pages] != sb_page) /* 0 is sb_page, release it below */

  			free_buffers(map[pages]);

  	kfree(map);

  	kfree(store->filemap_attr);

  	if (sb_page)
  		free_buffers(sb_page);

  	if (file) {

  		struct inode *inode = file_inode(file);

  		invalidate_mapping_pages(inode->i_mapping, 0, -1);

  		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 md_bitmap_file_kick(struct bitmap *bitmap)

  {
  	char *path, *ptr = NULL;

  	if (!test_and_set_bit(BITMAP_STALE, &bitmap->flags)) {

  		md_bitmap_update_sb(bitmap);

  		if (bitmap->storage.file) {

  			path = kmalloc(PAGE_SIZE, GFP_KERNEL);
  			if (path)

  				ptr = file_path(bitmap->storage.file,

  					     path, PAGE_SIZE);

  			pr_warn("%s: kicking failed bitmap file %s from array!
  ",
  				bmname(bitmap), IS_ERR(ptr) ? "" : ptr);

  			kfree(path);
  		} else

  			pr_warn("%s: disabling internal bitmap due to errors
  ",
  				bmname(bitmap));

  	}

  }
  
  enum bitmap_page_attr {

  	BITMAP_PAGE_DIRTY = 0,     /* there are set bits that need to be synced */

  	BITMAP_PAGE_PENDING = 1,   /* there are bits that are being cleaned.
  				    * i.e. counter is 1 or 2. */

  	BITMAP_PAGE_NEEDWRITE = 2, /* there are cleared bits that need to be synced */

  };

  static inline void set_page_attr(struct bitmap *bitmap, int pnum,
  				 enum bitmap_page_attr attr)

  {

  	set_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);

  }

  static inline void clear_page_attr(struct bitmap *bitmap, int pnum,
  				   enum bitmap_page_attr attr)

  {

  	clear_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);

  }

  static inline int test_page_attr(struct bitmap *bitmap, int pnum,
  				 enum bitmap_page_attr attr)

  {

  	return test_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);

  }

  static inline int test_and_clear_page_attr(struct bitmap *bitmap, int pnum,
  					   enum bitmap_page_attr attr)
  {
  	return test_and_clear_bit((pnum<<2) + attr,
  				  bitmap->storage.filemap_attr);
  }

  /*
   * 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 md_bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)

  {
  	unsigned long bit;

  	struct page *page;

  	void *kaddr;

  	unsigned long chunk = block >> bitmap->counts.chunkshift;

  	struct bitmap_storage *store = &bitmap->storage;
  	unsigned long node_offset = 0;
  
  	if (mddev_is_clustered(bitmap->mddev))
  		node_offset = bitmap->cluster_slot * store->file_pages;

  	page = filemap_get_page(&bitmap->storage, chunk);

  	if (!page)
  		return;

  	bit = file_page_offset(&bitmap->storage, chunk);

  	/* set the bit */

  	kaddr = kmap_atomic(page);

  	if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))

  		set_bit(bit, kaddr);
  	else

  		set_bit_le(bit, kaddr);

  	kunmap_atomic(kaddr);

  	pr_debug("set file bit %lu page %lu
  ", bit, page->index);

  	/* record page number so it gets flushed to disk when unplug occurs */

  	set_page_attr(bitmap, page->index - node_offset, BITMAP_PAGE_DIRTY);

  }

  static void md_bitmap_file_clear_bit(struct bitmap *bitmap, sector_t block)

  {
  	unsigned long bit;
  	struct page *page;
  	void *paddr;

  	unsigned long chunk = block >> bitmap->counts.chunkshift;

  	struct bitmap_storage *store = &bitmap->storage;
  	unsigned long node_offset = 0;
  
  	if (mddev_is_clustered(bitmap->mddev))
  		node_offset = bitmap->cluster_slot * store->file_pages;

  	page = filemap_get_page(&bitmap->storage, chunk);

  	if (!page)
  		return;

  	bit = file_page_offset(&bitmap->storage, chunk);

  	paddr = kmap_atomic(page);

  	if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))

  		clear_bit(bit, paddr);
  	else

  		clear_bit_le(bit, paddr);

  	kunmap_atomic(paddr);

  	if (!test_page_attr(bitmap, page->index - node_offset, BITMAP_PAGE_NEEDWRITE)) {
  		set_page_attr(bitmap, page->index - node_offset, BITMAP_PAGE_PENDING);

  		bitmap->allclean = 0;
  	}
  }

  static int md_bitmap_file_test_bit(struct bitmap *bitmap, sector_t block)

  {
  	unsigned long bit;
  	struct page *page;
  	void *paddr;
  	unsigned long chunk = block >> bitmap->counts.chunkshift;
  	int set = 0;
  
  	page = filemap_get_page(&bitmap->storage, chunk);
  	if (!page)
  		return -EINVAL;
  	bit = file_page_offset(&bitmap->storage, chunk);
  	paddr = kmap_atomic(page);
  	if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
  		set = test_bit(bit, paddr);
  	else
  		set = test_bit_le(bit, paddr);
  	kunmap_atomic(paddr);
  	return set;
  }

  /* 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 */

  void md_bitmap_unplug(struct bitmap *bitmap)

  {

  	unsigned long i;

  	int dirty, need_write;

  	int writing = 0;

  	if (!bitmap || !bitmap->storage.filemap ||
  	    test_bit(BITMAP_STALE, &bitmap->flags))

  		return;

  
  	/* 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->storage.file_pages; i++) {

  		dirty = test_and_clear_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
  		need_write = test_and_clear_page_attr(bitmap, i,
  						      BITMAP_PAGE_NEEDWRITE);
  		if (dirty || need_write) {

  			if (!writing) {

  				md_bitmap_wait_writes(bitmap);

  				if (bitmap->mddev->queue)
  					blk_add_trace_msg(bitmap->mddev->queue,
  							  "md bitmap_unplug");
  			}

  			clear_page_attr(bitmap, i, BITMAP_PAGE_PENDING);

  			write_page(bitmap, bitmap->storage.filemap[i], 0);

  			writing = 1;

  		}

  	}

  	if (writing)

  		md_bitmap_wait_writes(bitmap);

  	if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))

  		md_bitmap_file_kick(bitmap);

  }

  EXPORT_SYMBOL(md_bitmap_unplug);

  static void md_bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);

  /* * bitmap_init_from_disk -- called at bitmap_create time to initialize
   * the in-memory bitmap from the on-disk bitmap -- also, sets up the
   * memory mapping of the bitmap file
   * 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.

   *
   * We ignore all bits for sectors that end earlier than 'start'.
   * This is used when reading an out-of-date bitmap...

   */

  static int md_bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)

  {

  	unsigned long i, chunks, index, oldindex, bit, node_offset = 0;

  	struct page *page = NULL;

  	unsigned long bit_cnt = 0;

  	struct file *file;

  	unsigned long offset;

  	int outofdate;
  	int ret = -ENOSPC;

  	void *paddr;

  	struct bitmap_storage *store = &bitmap->storage;

  	chunks = bitmap->counts.chunks;

  	file = store->file;

  	if (!file && !bitmap->mddev->bitmap_info.offset) {
  		/* No permanent bitmap - fill with '1s'. */

  		store->filemap = NULL;
  		store->file_pages = 0;

  		for (i = 0; i < chunks ; i++) {
  			/* if the disk bit is set, set the memory bit */

  			int needed = ((sector_t)(i+1) << (bitmap->counts.chunkshift)

  				      >= start);

  			md_bitmap_set_memory_bits(bitmap,
  						  (sector_t)i << bitmap->counts.chunkshift,
  						  needed);

  		}
  		return 0;
  	}

  	outofdate = test_bit(BITMAP_STALE, &bitmap->flags);

  	if (outofdate)

  		pr_warn("%s: bitmap file is out of date, doing full recovery
  ", bmname(bitmap));

  	if (file && i_size_read(file->f_mapping->host) < store->bytes) {

  		pr_warn("%s: bitmap file too short %lu < %lu
  ",
  			bmname(bitmap),
  			(unsigned long) i_size_read(file->f_mapping->host),
  			store->bytes);

  		goto err;

  	}

  	oldindex = ~0L;

  	offset = 0;

  	if (!bitmap->mddev->bitmap_info.external)

  		offset = sizeof(bitmap_super_t);

  	if (mddev_is_clustered(bitmap->mddev))
  		node_offset = bitmap->cluster_slot * (DIV_ROUND_UP(store->bytes, PAGE_SIZE));

  	for (i = 0; i < chunks; i++) {

  		int b;

  		index = file_page_index(&bitmap->storage, i);
  		bit = file_page_offset(&bitmap->storage, 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 == store->file_pages-1)
  				count = store->bytes - index * PAGE_SIZE;

  			else
  				count = PAGE_SIZE;

  			page = store->filemap[index];

  			if (file)
  				ret = read_page(file, index, bitmap,
  						count, page);
  			else
  				ret = read_sb_page(
  					bitmap->mddev,
  					bitmap->mddev->bitmap_info.offset,
  					page,

  					index + node_offset, count);

  
  			if (ret)

  				goto err;

  			oldindex = index;

  
  			if (outofdate) {
  				/*
  				 * if bitmap is out of date, dirty the

  				 * whole page and write it out

  				 */

  				paddr = kmap_atomic(page);

  				memset(paddr + offset, 0xff,

  				       PAGE_SIZE - offset);

  				kunmap_atomic(paddr);

  				write_page(bitmap, page, 1);
  
  				ret = -EIO;

  				if (test_bit(BITMAP_WRITE_ERROR,
  					     &bitmap->flags))

  					goto err;

  			}

  		}

  		paddr = kmap_atomic(page);

  		if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))

  			b = test_bit(bit, paddr);

  		else

  			b = test_bit_le(bit, paddr);

  		kunmap_atomic(paddr);

  		if (b) {

  			/* if the disk bit is set, set the memory bit */

  			int needed = ((sector_t)(i+1) << bitmap->counts.chunkshift

  				      >= start);

  			md_bitmap_set_memory_bits(bitmap,
  						  (sector_t)i << bitmap->counts.chunkshift,
  						  needed);

  			bit_cnt++;
  		}

  		offset = 0;

  	}

  	pr_debug("%s: bitmap initialized from disk: read %lu pages, set %lu of %lu bits
  ",
  		 bmname(bitmap), store->file_pages,
  		 bit_cnt, chunks);

  
  	return 0;

   err:

  	pr_warn("%s: bitmap initialisation failed: %d
  ",
  		bmname(bitmap), ret);

  	return ret;
  }

  void md_bitmap_write_all(struct bitmap *bitmap)

  {
  	/* We don't actually write all bitmap blocks here,
  	 * just flag them as needing to be written
  	 */

  	int i;

  	if (!bitmap || !bitmap->storage.filemap)

  		return;

  	if (bitmap->storage.file)

  		/* Only one copy, so nothing needed */
  		return;

  	for (i = 0; i < bitmap->storage.file_pages; i++)

  		set_page_attr(bitmap, i,

  			      BITMAP_PAGE_NEEDWRITE);

  	bitmap->allclean = 0;

  }

  static void md_bitmap_count_page(struct bitmap_counts *bitmap,
  				 sector_t offset, int inc)

  {

  	sector_t chunk = offset >> bitmap->chunkshift;

  	unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
  	bitmap->bp[page].count += inc;

  	md_bitmap_checkfree(bitmap, page);

  }

  static void md_bitmap_set_pending(struct bitmap_counts *bitmap, sector_t offset)

  {
  	sector_t chunk = offset >> bitmap->chunkshift;
  	unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
  	struct bitmap_page *bp = &bitmap->bp[page];
  
  	if (!bp->pending)
  		bp->pending = 1;
  }

  static bitmap_counter_t *md_bitmap_get_counter(struct bitmap_counts *bitmap,
  					       sector_t offset, sector_t *blocks,
  					       int create);

  
  /*
   * bitmap daemon -- periodically wakes up to clean bits and flush pages
   *			out to disk
   */

  void md_bitmap_daemon_work(struct mddev *mddev)

  {

  	struct bitmap *bitmap;

  	unsigned long j;

  	unsigned long nextpage;

  	sector_t blocks;

  	struct bitmap_counts *counts;

  	/* 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

  			+ mddev->bitmap_info.daemon_sleep))

  		goto done;

  	bitmap->daemon_lastrun = jiffies;

  	if (bitmap->allclean) {

  		mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;

  		goto done;

  	}
  	bitmap->allclean = 1;

  	if (bitmap->mddev->queue)
  		blk_add_trace_msg(bitmap->mddev->queue,
  				  "md bitmap_daemon_work");

  	/* Any file-page which is PENDING now needs to be written.
  	 * So set NEEDWRITE now, then after we make any last-minute changes
  	 * we will write it.
  	 */

  	for (j = 0; j < bitmap->storage.file_pages; j++)

  		if (test_and_clear_page_attr(bitmap, j,
  					     BITMAP_PAGE_PENDING))

  			set_page_attr(bitmap, j,

  				      BITMAP_PAGE_NEEDWRITE);