<commit_before>/*
 * bitmap.c two-level bitmap (C) <NAME> (<EMAIL>) 2003
 *
 * bitmap_create  - sets up the bitmap structure
 * bitmap_destroy - destroys the bitmap structure
 *
 * additions, Copyright (C) 2003-2004, <NAME>, 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 "md.h"
#include "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 bitmap_checkpage(struct bitmap *bitmap,
			    unsigned long page, int create)
__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);
	mappage = kzalloc(PAGE_SIZE, GFP_NOIO);
	spin_lock_irq(&bitmap->lock);

	if (mappage == NULL) {
		pr_debug("%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 */
		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);
		return 0;
	} 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 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;
	} 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))
			continue;

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

		if (sync_page_io(rdev, target,
				 roundup(size, bdev_logical_block_size(rdev->bdev)),
				 page, READ, 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_continue_rcu.
	 */
	struct list_head *pos;
	rcu_read_lock();
	if (rdev == NULL)
		/* start at the beginning */
		pos = &mddev->disks;
	else {
		/* release the previous rdev and start from there. */
		rdev_dec_pending(rdev, mddev);
		pos = &rdev->same_set;
	}
	list_for_each_continue_rcu(pos, &mddev->disks) {
		rdev = list_entry(pos, struct md_rdev, 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 = NULL;
	struct block_device *bdev;
	struct mddev *mddev = bitmap->mddev;
	struct bitmap_storage *store = &bitmap->storage;

	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);
	return 0;

 bad_alignment:
	return -EINVAL;
}

static void 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:
			bitmap->flags |= BITMAP_WRITE_ERROR;
		}
	} 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(WRITE | REQ_SYNC, bh);
			bh = bh->b_this_page;
		}

		if (wait)
			wait_event(bitmap->write_wait,
				   atomic_read(&bitmap->pending_writes)==0);
	}
	if (bitmap->flags & BITMAP_WRITE_ERROR)
		bitmap_file_kick(bitmap);
}

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

	if (!uptodate) {
		spin_lock_irqsave(&bitmap->lock, flags);
		bitmap->flags |= BITMAP_WRITE_ERROR;
		spin_unlock_irqrestore(&bitmap->lock, flags);
	}
	if (atomic_dec_and_test(&bitmap->pending_writes))
		wake_up(&bitmap->write_wait);
}

/* copied from buffer.c */
static void
__clear_page_buffers(struct page *page)
{
	ClearPagePrivate(page);
	set_page_private(page, 0);
	page_cache_release(page);
}
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;
	}
	__clear_page_buffers(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->f_path.dentry->d_inode;
	struct buffer_head *bh;
	sector_t block;

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

	bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
	if (!bh) {
		ret = -ENOMEM;
		goto out;
	}
	attach_page_buffers(page, bh);
	block = index << (PAGE_SHIFT - inode->i_blkbits);
	while (bh) {
		if (count == 0)
			bh->b_blocknr = 0;
		else {
			bh->b_blocknr = bmap(inode, block);
			if (bh->b_blocknr == 0) {
				/* Cannot use this file! */
				ret = -EINVAL;
				goto out;
			}
			bh->b_bdev = inode->i_sb->s_bdev;
			if (count < (1<<inode->i_blkbits))
				count = 0;
			else
				count -= (1<<inode->i_blkbits);

			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(READ, bh);
		}
		block++;
		bh = bh->b_this_page;
	}
	page->index = index;

	wait_event(bitmap->write_wait,
		   atomic_read(&bitmap->pending_writes)==0);
	if (bitmap->flags & BITMAP_WRITE_ERROR)
		ret = -EIO;
out:
	if (ret)
		printk(KERN_ALERT "md: bitmap read error: (%dB @ %llu): %d\n",
			(int)PAGE_SIZE,
			(unsigned long long)index << PAGE_SHIFT,
			ret);
	return ret;
}

/*
 * bitmap file superblock operations
 */

/* update the event counter and sync the superblock to disk */
void 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);
	sb->state = cpu_to_le32(bitmap->flags);
	/* 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);
	write_page(bitmap, bitmap->storage.sb_page, 1);
}

/* print out the bitmap file superblock */
void bitmap_print_sb(struct bitmap *bitmap)
{
	bitmap_super_t *sb;

	if (!bitmap || !bitmap->storage.sb_page)
		return;
	sb = kmap_atomic(bitmap->storage.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 cleared: %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",
			(unsigned long long)le64_to_cpu(sb->sync_size)/2);
	printk(KERN_DEBUG "max write behind: %d\n", 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 bitmap_new_disk_sb(struct bitmap *bitmap)
{
	bitmap_super_t *sb;
	unsigned long chunksize, daemon_sleep, write_behind;
	int err = -EINVAL;

	bitmap->storage.sb_page = alloc_page(GFP_KERNEL);
	if (IS_ERR(bitmap->storage.sb_page)) {
		err = PTR_ERR(bitmap->storage.sb_page);
		bitmap->storage.sb_page = NULL;
		return err;
	}
	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);
		printk(KERN_ERR "bitmap chunksize not a power of 2\n");
		return -EINVAL;
	}
	sb->chunksize = cpu_to_le32(chunksize);

	daemon_sleep = bitmap->mddev->bitmap_info.daemon_sleep;
	if (!daemon_sleep ||
	    (daemon_sleep < 1) || (daemon_sleep > MAX_SCHEDULE_TIMEOUT)) {
		printk(KERN_INFO "Choosing daemon_sleep default (5 sec)\n");
		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);

	bitmap->flags |= BITMAP_STALE;
	sb->state |= cpu_to_le32(BITMAP_STALE);
	bitmap->events_cleared = bitmap->mddev->events;
	sb->events_cleared = cpu_to_le64(bitmap->mddev->events);

	kunmap_atomic(sb);

	return 0;
}

/* 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, write_behind;
	unsigned long long events;
	int err = -EINVAL;
	struct page *sb_page;

	if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
		chunksize = 128 * 1024 * 1024;
		daemon_sleep = 5 * HZ;
		write_behind = 0;
		bitmap->flags = BITMAP_STALE;
		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;

	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,
				   bitmap->mddev->bitmap_info.offset,
				   sb_page,
				   0, sizeof(bitmap_super_t));
	}
	if (err)
		return err;

	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);

	/* 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_HI)
		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) {
		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) {
		/*
		 * 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)) {
			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 |= cpu_to_le32(BITMAP_STALE);
		}
	}

	/* assign fields using values from superblock */
	bitmap->flags |= le32_to_cpu(sb->state);
	if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
		bitmap->flags |= BITMAP_HOSTENDIAN;
	bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
	err = 0;
out:
	kunmap_atomic(sb);
out_no_sb:
	if (bitmap->flags & BITMAP_STALE)
		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;
	if (err)
		bitmap_print_sb(bitmap);
	return err;
}<commit_msg>md/bitmap: remove single-bit manipulation on sb->state<commit_after>/*
 * bitmap.c two-level bitmap (C) <NAME> (<EMAIL>) 2003
 *
 * bitmap_create  - sets up the bitmap structure
 * bitmap_destroy - destroys the bitmap structure
 *
 * additions, Copyright (C) 2003-2004, <NAME>, 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 "md.h"
#include "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 bitmap_checkpage(struct bitmap *bitmap,
			    unsigned long page, int create)
__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);
	mappage = kzalloc(PAGE_SIZE, GFP_NOIO);
	spin_lock_irq(&bitmap->lock);

	if (mappage == NULL) {
		pr_debug("%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 */
		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);
		return 0;
	} 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 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;
	} 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))
			continue;

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

		if (sync_page_io(rdev, target,
				 roundup(size, bdev_logical_block_size(rdev->bdev)),
				 page, READ, 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_continue_rcu.
	 */
	struct list_head *pos;
	rcu_read_lock();
	if (rdev == NULL)
		/* start at the beginning */
		pos = &mddev->disks;
	else {
		/* release the previous rdev and start from there. */
		rdev_dec_pending(rdev, mddev);
		pos = &rdev->same_set;
	}
	list_for_each_continue_rcu(pos, &mddev->disks) {
		rdev = list_entry(pos, struct md_rdev, 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 = NULL;
	struct block_device *bdev;
	struct mddev *mddev = bitmap->mddev;
	struct bitmap_storage *store = &bitmap->storage;

	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);
	return 0;

 bad_alignment:
	return -EINVAL;
}

static void 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:
			bitmap->flags |= BITMAP_WRITE_ERROR;
		}
	} 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(WRITE | REQ_SYNC, bh);
			bh = bh->b_this_page;
		}

		if (wait)
			wait_event(bitmap->write_wait,
				   atomic_read(&bitmap->pending_writes)==0);
	}
	if (bitmap->flags & BITMAP_WRITE_ERROR)
		bitmap_file_kick(bitmap);
}

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

	if (!uptodate) {
		spin_lock_irqsave(&bitmap->lock, flags);
		bitmap->flags |= BITMAP_WRITE_ERROR;
		spin_unlock_irqrestore(&bitmap->lock, flags);
	}
	if (atomic_dec_and_test(&bitmap->pending_writes))
		wake_up(&bitmap->write_wait);
}

/* copied from buffer.c */
static void
__clear_page_buffers(struct page *page)
{
	ClearPagePrivate(page);
	set_page_private(page, 0);
	page_cache_release(page);
}
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;
	}
	__clear_page_buffers(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->f_path.dentry->d_inode;
	struct buffer_head *bh;
	sector_t block;

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

	bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
	if (!bh) {
		ret = -ENOMEM;
		goto out;
	}
	attach_page_buffers(page, bh);
	block = index << (PAGE_SHIFT - inode->i_blkbits);
	while (bh) {
		if (count == 0)
			bh->b_blocknr = 0;
		else {
			bh->b_blocknr = bmap(inode, block);
			if (bh->b_blocknr == 0) {
				/* Cannot use this file! */
				ret = -EINVAL;
				goto out;
			}
			bh->b_bdev = inode->i_sb->s_bdev;
			if (count < (1<<inode->i_blkbits))
				count = 0;
			else
				count -= (1<<inode->i_blkbits);

			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(READ, bh);
		}
		block++;
		bh = bh->b_this_page;
	}
	page->index = index;

	wait_event(bitmap->write_wait,
		   atomic_read(&bitmap->pending_writes)==0);
	if (bitmap->flags & BITMAP_WRITE_ERROR)
		ret = -EIO;
out:
	if (ret)
		printk(KERN_ALERT "md: bitmap read error: (%dB @ %llu): %d\n",
			(int)PAGE_SIZE,
			(unsigned long long)index << PAGE_SHIFT,
			ret);
	return ret;
}

/*
 * bitmap file superblock operations
 */

/* update the event counter and sync the superblock to disk */
void 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);
	sb->state = cpu_to_le32(bitmap->flags);
	/* 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);
	write_page(bitmap, bitmap->storage.sb_page, 1);
}

/* print out the bitmap file superblock */
void bitmap_print_sb(struct bitmap *bitmap)
{
	bitmap_super_t *sb;

	if (!bitmap || !bitmap->storage.sb_page)
		return;
	sb = kmap_atomic(bitmap->storage.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 cleared: %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",
			(unsigned long long)le64_to_cpu(sb->sync_size)/2);
	printk(KERN_DEBUG "max write behind: %d\n", 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 bitmap_new_disk_sb(struct bitmap *bitmap)
{
	bitmap_super_t *sb;
	unsigned long chunksize, daemon_sleep, write_behind;
	int err = -EINVAL;

	bitmap->storage.sb_page = alloc_page(GFP_KERNEL);
	if (IS_ERR(bitmap->storage.sb_page)) {
		err = PTR_ERR(bitmap->storage.sb_page);
		bitmap->storage.sb_page = NULL;
		return err;
	}
	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);
		printk(KERN_ERR "bitmap chunksize not a power of 2\n");
		return -EINVAL;
	}
	sb->chunksize = cpu_to_le32(chunksize);

	daemon_sleep = bitmap->mddev->bitmap_info.daemon_sleep;
	if (!daemon_sleep ||
	    (daemon_sleep < 1) || (daemon_sleep > MAX_SCHEDULE_TIMEOUT)) {
		printk(KERN_INFO "Choosing daemon_sleep default (5 sec)\n");
		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);

	bitmap->flags |= BITMAP_STALE;
	sb->state = cpu_to_le32(bitmap->flags);
	bitmap->events_cleared = bitmap->mddev->events;
	sb->events_cleared = cpu_to_le64(bitmap->mddev->events);

	kunmap_atomic(sb);

	return 0;
}

/* 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, write_behind;
	unsigned long long events;
	int err = -EINVAL;
	struct page *sb_page;

	if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
		chunksize = 128 * 1024 * 1024;
		daemon_sleep = 5 * HZ;
		write_behind = 0;
		bitmap->flags = BITMAP_STALE;
		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;

	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,
				   bitmap->mddev->bitmap_info.offset,
				   sb_page,
				   0, sizeof(bitmap_super_t));
	}
	if (err)
		return err;

	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);

	/* 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_HI)
		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) {
		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) {
		/*
		 * 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)) {
			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);
			bitmap->flags |= BITMAP_STALE;
		}
	}

	/* assign fields using values from superblock */
	bitmap->flags |= le32_to_cpu(sb->state);
	if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
		bitmap->flags |= BITMAP_HOSTENDIAN;
	bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
	err = 0;
out:
	kunmap_atomic(sb);
out_no_sb:
	if (bitmap->flags & BITMAP_STALE)
		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;
	if (err)
		bitmap_print_sb(bitmap);
	return err;
}
{'fraction_non_alphanumeric': 0.13269358041032428, 'fraction_numerical': 0.011305978380763292, 'mean_word_length': 3.710963886723824, 'pattern_counts': {'":': 0, '<': 81, '<?xml version=': 0, '>': 497, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
{'dir': 'git-commits-cleaned', 'id': '1635081', 'n_tokens_mistral': 14236, 'n_tokens_neox': 13229, 'n_words': 3383}