bitmap.c 42.5 KB
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/*
 * bitmap.c two-level bitmap (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
 *
 * bitmap_create  - sets up the bitmap structure
 * bitmap_destroy - destroys the bitmap structure
 *
 * additions, Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.:
 * - added disk storage for bitmap
 * - changes to allow various bitmap chunk sizes
 * - added bitmap daemon (to asynchronously clear bitmap bits from disk)
 */

/*
 * Still to do:
 *
 * flush after percent set rather than just time based. (maybe both).
 * wait if count gets too high, wake when it drops to half.
 * allow bitmap to be mirrored with superblock (before or after...)
 * allow hot-add to re-instate a current device.
 * allow hot-add of bitmap after quiessing device
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/config.h>
#include <linux/timer.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/buffer_head.h>
#include <linux/raid/md.h>
#include <linux/raid/bitmap.h>

/* debug macros */

#define DEBUG 0

#if DEBUG
/* these are for debugging purposes only! */

/* define one and only one of these */
#define INJECT_FAULTS_1 0 /* cause bitmap_alloc_page to fail always */
#define INJECT_FAULTS_2 0 /* cause bitmap file to be kicked when first bit set*/
#define INJECT_FAULTS_3 0 /* treat bitmap file as kicked at init time */
#define INJECT_FAULTS_4 0 /* undef */
#define INJECT_FAULTS_5 0 /* undef */
#define INJECT_FAULTS_6 0

/* if these are defined, the driver will fail! debug only */
#define INJECT_FATAL_FAULT_1 0 /* fail kmalloc, causing bitmap_create to fail */
#define INJECT_FATAL_FAULT_2 0 /* undef */
#define INJECT_FATAL_FAULT_3 0 /* undef */
#endif

//#define DPRINTK PRINTK /* set this NULL to avoid verbose debug output */
#define DPRINTK(x...) do { } while(0)

#ifndef PRINTK
#  if DEBUG > 0
#    define PRINTK(x...) printk(KERN_DEBUG x)
#  else
#    define PRINTK(x...)
#  endif
#endif

static inline char * bmname(struct bitmap *bitmap)
{
	return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
}


/*
 * test if the bitmap is active
 */
int bitmap_active(struct bitmap *bitmap)
{
	unsigned long flags;
	int res = 0;

	if (!bitmap)
		return res;
	spin_lock_irqsave(&bitmap->lock, flags);
	res = bitmap->flags & BITMAP_ACTIVE;
	spin_unlock_irqrestore(&bitmap->lock, flags);
	return res;
}

#define WRITE_POOL_SIZE 256
/* mempool for queueing pending writes on the bitmap file */
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static void *write_pool_alloc(gfp_t gfp_flags, void *data)
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{
	return kmalloc(sizeof(struct page_list), gfp_flags);
}

static void write_pool_free(void *ptr, void *data)
{
	kfree(ptr);
}

/*
 * just a placeholder - calls kmalloc for bitmap pages
 */
static unsigned char *bitmap_alloc_page(struct bitmap *bitmap)
{
	unsigned char *page;

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#ifdef INJECT_FAULTS_1
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	page = NULL;
#else
	page = kmalloc(PAGE_SIZE, GFP_NOIO);
#endif
	if (!page)
		printk("%s: bitmap_alloc_page FAILED\n", bmname(bitmap));
	else
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		PRINTK("%s: bitmap_alloc_page: allocated page at %p\n",
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			bmname(bitmap), page);
	return page;
}

/*
 * for now just a placeholder -- just calls kfree for bitmap pages
 */
static void bitmap_free_page(struct bitmap *bitmap, unsigned char *page)
{
	PRINTK("%s: bitmap_free_page: free page %p\n", bmname(bitmap), page);
	kfree(page);
}

/*
 * check a page and, if necessary, allocate it (or hijack it if the alloc fails)
 *
 * 1) check to see if this page is allocated, if it's not then try to alloc
 * 2) if the alloc fails, set the page's hijacked flag so we'll use the
 *    page pointer directly as a counter
 *
 * if we find our page, we increment the page's refcount so that it stays
 * allocated while we're using it
 */
static int bitmap_checkpage(struct bitmap *bitmap, unsigned long page, int create)
{
	unsigned char *mappage;

	if (page >= bitmap->pages) {
		printk(KERN_ALERT
			"%s: invalid bitmap page request: %lu (> %lu)\n",
			bmname(bitmap), page, bitmap->pages-1);
		return -EINVAL;
	}


	if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
		return 0;

	if (bitmap->bp[page].map) /* page is already allocated, just return */
		return 0;

	if (!create)
		return -ENOENT;

	spin_unlock_irq(&bitmap->lock);

	/* this page has not been allocated yet */

	if ((mappage = bitmap_alloc_page(bitmap)) == NULL) {
		PRINTK("%s: bitmap map page allocation failed, hijacking\n",
			bmname(bitmap));
		/* failed - set the hijacked flag so that we can use the
		 * pointer as a counter */
		spin_lock_irq(&bitmap->lock);
		if (!bitmap->bp[page].map)
			bitmap->bp[page].hijacked = 1;
		goto out;
	}

	/* got a page */

	spin_lock_irq(&bitmap->lock);

	/* recheck the page */

	if (bitmap->bp[page].map || bitmap->bp[page].hijacked) {
		/* somebody beat us to getting the page */
		bitmap_free_page(bitmap, mappage);
		return 0;
	}

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

	memset(mappage, 0, PAGE_SIZE);
	bitmap->bp[page].map = mappage;
	bitmap->missing_pages--;
out:
	return 0;
}


/* if page is completely empty, put it back on the free list, or dealloc it */
/* if page was hijacked, unmark the flag so it might get alloced next time */
/* Note: lock should be held when calling this */
static inline void bitmap_checkfree(struct bitmap *bitmap, unsigned long page)
{
	char *ptr;

	if (bitmap->bp[page].count) /* page is still busy */
		return;

	/* page is no longer in use, it can be released */

	if (bitmap->bp[page].hijacked) { /* page was hijacked, undo this now */
		bitmap->bp[page].hijacked = 0;
		bitmap->bp[page].map = NULL;
		return;
	}

	/* normal case, free the page */

#if 0
/* actually ... let's not.  We will probably need the page again exactly when
 * memory is tight and we are flusing to disk
 */
	return;
#else
	ptr = bitmap->bp[page].map;
	bitmap->bp[page].map = NULL;
	bitmap->missing_pages++;
	bitmap_free_page(bitmap, ptr);
	return;
#endif
}


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

/* copy the pathname of a file to a buffer */
char *file_path(struct file *file, char *buf, int count)
{
	struct dentry *d;
	struct vfsmount *v;

	if (!buf)
		return NULL;

	d = file->f_dentry;
	v = file->f_vfsmnt;

	buf = d_path(d, v, buf, count);

	return IS_ERR(buf) ? NULL : buf;
}

/*
 * basic page I/O operations
 */

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/* IO operations when bitmap is stored near all superblocks */
static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long index)
{
	/* choose a good rdev and read the page from there */

	mdk_rdev_t *rdev;
	struct list_head *tmp;
	struct page *page = alloc_page(GFP_KERNEL);
	sector_t target;

	if (!page)
		return ERR_PTR(-ENOMEM);

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	ITERATE_RDEV(mddev, rdev, tmp) {
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		if (! test_bit(In_sync, &rdev->flags)
		    || test_bit(Faulty, &rdev->flags))
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			continue;

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		target = (rdev->sb_offset << 1) + offset + index * (PAGE_SIZE/512);

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		if (sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ)) {
			page->index = index;
			return page;
		}
	}
	return ERR_PTR(-EIO);
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}

static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wait)
{
	mdk_rdev_t *rdev;
	struct list_head *tmp;

	ITERATE_RDEV(mddev, rdev, tmp)
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		if (test_bit(In_sync, &rdev->flags)
		    && !test_bit(Faulty, &rdev->flags))
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			md_super_write(mddev, rdev,
				       (rdev->sb_offset<<1) + offset
				       + page->index * (PAGE_SIZE/512),
				       PAGE_SIZE,
				       page);

	if (wait)
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		md_super_wait(mddev);
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	return 0;
}

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/*
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 * write out a page to a file
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 */
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static int write_page(struct bitmap *bitmap, struct page *page, int wait)
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{
	int ret = -ENOMEM;

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	if (bitmap->file == NULL)
		return write_sb_page(bitmap->mddev, bitmap->offset, page, wait);

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	if (wait)
		lock_page(page);
	else {
		if (TestSetPageLocked(page))
			return -EAGAIN; /* already locked */
		if (PageWriteback(page)) {
			unlock_page(page);
			return -EAGAIN;
		}
	}
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	ret = page->mapping->a_ops->prepare_write(bitmap->file, page, 0, PAGE_SIZE);
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	if (!ret)
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		ret = page->mapping->a_ops->commit_write(bitmap->file, page, 0,
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			PAGE_SIZE);
	if (ret) {
		unlock_page(page);
		return ret;
	}

	set_page_dirty(page); /* force it to be written out */
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	if (!wait) {
		/* add to list to be waited for by daemon */
		struct page_list *item = mempool_alloc(bitmap->write_pool, GFP_NOIO);
		item->page = page;
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		get_page(page);
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		spin_lock(&bitmap->write_lock);
		list_add(&item->list, &bitmap->complete_pages);
		spin_unlock(&bitmap->write_lock);
		md_wakeup_thread(bitmap->writeback_daemon);
	}
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	return write_one_page(page, wait);
}

/* read a page from a file, pinning it into cache, and return bytes_read */
static struct page *read_page(struct file *file, unsigned long index,
					unsigned long *bytes_read)
{
	struct inode *inode = file->f_mapping->host;
	struct page *page = NULL;
	loff_t isize = i_size_read(inode);
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	unsigned long end_index = isize >> PAGE_SHIFT;
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	PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_SIZE,
			(unsigned long long)index << PAGE_SHIFT);
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	page = read_cache_page(inode->i_mapping, index,
			(filler_t *)inode->i_mapping->a_ops->readpage, file);
	if (IS_ERR(page))
		goto out;
	wait_on_page_locked(page);
	if (!PageUptodate(page) || PageError(page)) {
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		put_page(page);
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		page = ERR_PTR(-EIO);
		goto out;
	}

	if (index > end_index) /* we have read beyond EOF */
		*bytes_read = 0;
	else if (index == end_index) /* possible short read */
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		*bytes_read = isize & ~PAGE_MASK;
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	else
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		*bytes_read = PAGE_SIZE; /* got a full page */
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out:
	if (IS_ERR(page))
		printk(KERN_ALERT "md: bitmap read error: (%dB @ %Lu): %ld\n",
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			(int)PAGE_SIZE,
			(unsigned long long)index << PAGE_SHIFT,
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			PTR_ERR(page));
	return page;
}

/*
 * bitmap file superblock operations
 */

/* update the event counter and sync the superblock to disk */
int bitmap_update_sb(struct bitmap *bitmap)
{
	bitmap_super_t *sb;
	unsigned long flags;

	if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
		return 0;
	spin_lock_irqsave(&bitmap->lock, flags);
	if (!bitmap->sb_page) { /* no superblock */
		spin_unlock_irqrestore(&bitmap->lock, flags);
		return 0;
	}
	spin_unlock_irqrestore(&bitmap->lock, flags);
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	sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
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	sb->events = cpu_to_le64(bitmap->mddev->events);
	if (!bitmap->mddev->degraded)
		sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
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	kunmap_atomic(sb, KM_USER0);
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	return write_page(bitmap, bitmap->sb_page, 1);
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}

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

	if (!bitmap || !bitmap->sb_page)
		return;
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	sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
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	printk(KERN_DEBUG "%s: bitmap file superblock:\n", bmname(bitmap));
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	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",
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					*(__u32 *)(sb->uuid+0),
					*(__u32 *)(sb->uuid+4),
					*(__u32 *)(sb->uuid+8),
					*(__u32 *)(sb->uuid+12));
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	printk(KERN_DEBUG "        events: %llu\n",
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			(unsigned long long) le64_to_cpu(sb->events));
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	printk(KERN_DEBUG "events cleared: %llu\n",
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			(unsigned long long) le64_to_cpu(sb->events_cleared));
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	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);
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	printk(KERN_DEBUG "max write behind: %d\n", le32_to_cpu(sb->write_behind));
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	kunmap_atomic(sb, KM_USER0);
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}

/* 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;
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	unsigned long chunksize, daemon_sleep, write_behind;
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	unsigned long bytes_read;
	unsigned long long events;
	int err = -EINVAL;

	/* page 0 is the superblock, read it... */
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	if (bitmap->file)
		bitmap->sb_page = read_page(bitmap->file, 0, &bytes_read);
	else {
		bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset, 0);
		bytes_read = PAGE_SIZE;
	}
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	if (IS_ERR(bitmap->sb_page)) {
		err = PTR_ERR(bitmap->sb_page);
		bitmap->sb_page = NULL;
		return err;
	}

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	sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
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	if (bytes_read < sizeof(*sb)) { /* short read */
		printk(KERN_INFO "%s: bitmap file superblock truncated\n",
			bmname(bitmap));
		err = -ENOSPC;
		goto out;
	}

	chunksize = le32_to_cpu(sb->chunksize);
	daemon_sleep = le32_to_cpu(sb->daemon_sleep);
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	write_behind = le32_to_cpu(sb->write_behind);
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	/* verify that the bitmap-specific fields are valid */
	if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
		reason = "bad magic";
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	else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
		 le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
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		reason = "unrecognized superblock version";
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	else if (chunksize < PAGE_SIZE)
		reason = "bitmap chunksize too small";
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	else if ((1 << ffz(~chunksize)) != chunksize)
		reason = "bitmap chunksize not a power of 2";
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	else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT / HZ)
		reason = "daemon sleep period out of range";
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	else if (write_behind > COUNTER_MAX)
		reason = "write-behind limit out of range (0 - 16383)";
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	if (reason) {
		printk(KERN_INFO "%s: invalid bitmap file superblock: %s\n",
			bmname(bitmap), reason);
		goto out;
	}

	/* keep the array size field of the bitmap superblock up to date */
	sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);

	if (!bitmap->mddev->persistent)
		goto success;

	/*
	 * if we have a persistent array superblock, compare the
	 * bitmap's UUID and event counter to the mddev's
	 */
	if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
		printk(KERN_INFO "%s: bitmap superblock UUID mismatch\n",
			bmname(bitmap));
		goto out;
	}
	events = le64_to_cpu(sb->events);
	if (events < bitmap->mddev->events) {
		printk(KERN_INFO "%s: bitmap file is out of date (%llu < %llu) "
			"-- forcing full recovery\n", bmname(bitmap), events,
			(unsigned long long) bitmap->mddev->events);
		sb->state |= BITMAP_STALE;
	}
success:
	/* assign fields using values from superblock */
	bitmap->chunksize = chunksize;
	bitmap->daemon_sleep = daemon_sleep;
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	bitmap->daemon_lastrun = jiffies;
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	bitmap->max_write_behind = write_behind;
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	bitmap->flags |= sb->state;
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	if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
		bitmap->flags |= BITMAP_HOSTENDIAN;
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	bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
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	if (sb->state & BITMAP_STALE)
		bitmap->events_cleared = bitmap->mddev->events;
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	err = 0;
out:
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	kunmap_atomic(sb, KM_USER0);
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	if (err)
		bitmap_print_sb(bitmap);
	return err;
}

enum bitmap_mask_op {
	MASK_SET,
	MASK_UNSET
};

/* record the state of the bitmap in the superblock */
static void bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
				enum bitmap_mask_op op)
{
	bitmap_super_t *sb;
	unsigned long flags;

	spin_lock_irqsave(&bitmap->lock, flags);
	if (!bitmap || !bitmap->sb_page) { /* can't set the state */
		spin_unlock_irqrestore(&bitmap->lock, flags);
		return;
	}
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	get_page(bitmap->sb_page);
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	spin_unlock_irqrestore(&bitmap->lock, flags);
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	sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
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	switch (op) {
		case MASK_SET: sb->state |= bits;
				break;
		case MASK_UNSET: sb->state &= ~bits;
				break;
		default: BUG();
	}
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	kunmap_atomic(sb, KM_USER0);
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	put_page(bitmap->sb_page);
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}

/*
 * general bitmap file operations
 */

/* calculate the index of the page that contains this bit */
static inline unsigned long file_page_index(unsigned long chunk)
{
	return CHUNK_BIT_OFFSET(chunk) >> PAGE_BIT_SHIFT;
}

/* calculate the (bit) offset of this bit within a page */
static inline unsigned long file_page_offset(unsigned long chunk)
{
	return CHUNK_BIT_OFFSET(chunk) & (PAGE_BITS - 1);
}

/*
 * return a pointer to the page in the filemap that contains the given bit
 *
 * this lookup is complicated by the fact that the bitmap sb might be exactly
 * 1 page (e.g., x86) or less than 1 page -- so the bitmap might start on page
 * 0 or page 1
 */
static inline struct page *filemap_get_page(struct bitmap *bitmap,
					unsigned long chunk)
{
	return bitmap->filemap[file_page_index(chunk) - file_page_index(0)];
}


static void bitmap_file_unmap(struct bitmap *bitmap)
{
	struct page **map, *sb_page;
	unsigned long *attr;
	int pages;
	unsigned long flags;

	spin_lock_irqsave(&bitmap->lock, flags);
	map = bitmap->filemap;
	bitmap->filemap = NULL;
	attr = bitmap->filemap_attr;
	bitmap->filemap_attr = NULL;
	pages = bitmap->file_pages;
	bitmap->file_pages = 0;
	sb_page = bitmap->sb_page;
	bitmap->sb_page = NULL;
	spin_unlock_irqrestore(&bitmap->lock, flags);

	while (pages--)
		if (map[pages]->index != 0) /* 0 is sb_page, release it below */
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			put_page(map[pages]);
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	kfree(map);
	kfree(attr);

	if (sb_page)
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		put_page(sb_page);
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}

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static void bitmap_stop_daemon(struct bitmap *bitmap);
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/* dequeue the next item in a page list -- don't call from irq context */
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static struct page_list *dequeue_page(struct bitmap *bitmap)
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{
	struct page_list *item = NULL;
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	struct list_head *head = &bitmap->complete_pages;
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	spin_lock(&bitmap->write_lock);
	if (list_empty(head))
		goto out;
	item = list_entry(head->prev, struct page_list, list);
	list_del(head->prev);
out:
	spin_unlock(&bitmap->write_lock);
	return item;
}

static void drain_write_queues(struct bitmap *bitmap)
{
	struct page_list *item;

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	while ((item = dequeue_page(bitmap))) {
		/* don't bother to wait */
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		put_page(item->page);
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		mempool_free(item, bitmap->write_pool);
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	}

	wake_up(&bitmap->write_wait);
}

static void bitmap_file_put(struct bitmap *bitmap)
{
	struct file *file;
	struct inode *inode;
	unsigned long flags;

	spin_lock_irqsave(&bitmap->lock, flags);
	file = bitmap->file;
	bitmap->file = NULL;
	spin_unlock_irqrestore(&bitmap->lock, flags);

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	bitmap_stop_daemon(bitmap);
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	drain_write_queues(bitmap);

	bitmap_file_unmap(bitmap);

	if (file) {
		inode = file->f_mapping->host;
		spin_lock(&inode->i_lock);
		atomic_set(&inode->i_writecount, 1); /* allow writes again */
		spin_unlock(&inode->i_lock);
		fput(file);
	}
}


/*
 * bitmap_file_kick - if an error occurs while manipulating the bitmap file
 * then it is no longer reliable, so we stop using it and we mark the file
 * as failed in the superblock
 */
static void bitmap_file_kick(struct bitmap *bitmap)
{
	char *path, *ptr = NULL;

	bitmap_mask_state(bitmap, BITMAP_STALE, MASK_SET);
	bitmap_update_sb(bitmap);

703 704 705 706
	if (bitmap->file) {
		path = kmalloc(PAGE_SIZE, GFP_KERNEL);
		if (path)
			ptr = file_path(bitmap->file, path, PAGE_SIZE);
707

708 709
		printk(KERN_ALERT "%s: kicking failed bitmap file %s from array!\n",
		       bmname(bitmap), ptr ? ptr : "");
710

711 712
		kfree(path);
	}
713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755

	bitmap_file_put(bitmap);

	return;
}

enum bitmap_page_attr {
	BITMAP_PAGE_DIRTY = 1, // there are set bits that need to be synced
	BITMAP_PAGE_CLEAN = 2, // there are bits that might need to be cleared
	BITMAP_PAGE_NEEDWRITE=4, // there are cleared bits that need to be synced
};

static inline void set_page_attr(struct bitmap *bitmap, struct page *page,
				enum bitmap_page_attr attr)
{
	bitmap->filemap_attr[page->index] |= attr;
}

static inline void clear_page_attr(struct bitmap *bitmap, struct page *page,
				enum bitmap_page_attr attr)
{
	bitmap->filemap_attr[page->index] &= ~attr;
}

static inline unsigned long get_page_attr(struct bitmap *bitmap, struct page *page)
{
	return bitmap->filemap_attr[page->index];
}

/*
 * bitmap_file_set_bit -- called before performing a write to the md device
 * to set (and eventually sync) a particular bit in the bitmap file
 *
 * we set the bit immediately, then we record the page number so that
 * when an unplug occurs, we can flush the dirty pages out to disk
 */
static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
{
	unsigned long bit;
	struct page *page;
	void *kaddr;
	unsigned long chunk = block >> CHUNK_BLOCK_SHIFT(bitmap);

756
	if (!bitmap->filemap) {
757 758 759 760 761 762 763 764 765
		return;
	}

	page = filemap_get_page(bitmap, chunk);
	bit = file_page_offset(chunk);


	/* make sure the page stays cached until it gets written out */
	if (! (get_page_attr(bitmap, page) & BITMAP_PAGE_DIRTY))
766
		get_page(page);
767 768 769

 	/* set the bit */
	kaddr = kmap_atomic(page, KM_USER0);
770 771 772 773
	if (bitmap->flags & BITMAP_HOSTENDIAN)
		set_bit(bit, kaddr);
	else
		ext2_set_bit(bit, kaddr);
774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789
	kunmap_atomic(kaddr, KM_USER0);
	PRINTK("set file bit %lu page %lu\n", bit, page->index);

	/* record page number so it gets flushed to disk when unplug occurs */
	set_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);

}

/* this gets called when the md device is ready to unplug its underlying
 * (slave) device queues -- before we let any writes go down, we need to
 * sync the dirty pages of the bitmap file to disk */
int bitmap_unplug(struct bitmap *bitmap)
{
	unsigned long i, attr, flags;
	struct page *page;
	int wait = 0;
790
	int err;
791 792 793 794 795 796 797 798

	if (!bitmap)
		return 0;

	/* look at each page to see if there are any set bits that need to be
	 * flushed out to disk */
	for (i = 0; i < bitmap->file_pages; i++) {
		spin_lock_irqsave(&bitmap->lock, flags);
799
		if (!bitmap->filemap) {
800 801 802 803 804 805 806 807 808 809 810
			spin_unlock_irqrestore(&bitmap->lock, flags);
			return 0;
		}
		page = bitmap->filemap[i];
		attr = get_page_attr(bitmap, page);
		clear_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
		clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
		if ((attr & BITMAP_PAGE_DIRTY))
			wait = 1;
		spin_unlock_irqrestore(&bitmap->lock, flags);

811 812 813 814 815 816 817 818 819
		if (attr & (BITMAP_PAGE_DIRTY | BITMAP_PAGE_NEEDWRITE)) {
			err = write_page(bitmap, page, 0);
			if (err == -EAGAIN) {
				if (attr & BITMAP_PAGE_DIRTY)
					err = write_page(bitmap, page, 1);
				else
					err = 0;
			}
			if (err)
820
				return 1;
821
		}
822 823
	}
	if (wait) { /* if any writes were performed, we need to wait on them */
824 825 826 827 828 829 830
		if (bitmap->file) {
			spin_lock_irq(&bitmap->write_lock);
			wait_event_lock_irq(bitmap->write_wait,
					    list_empty(&bitmap->complete_pages), bitmap->write_lock,
					    wake_up_process(bitmap->writeback_daemon->tsk));
			spin_unlock_irq(&bitmap->write_lock);
		} else
831
			md_super_wait(bitmap->mddev);
832 833 834 835
	}
	return 0;
}

836
static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
837 838 839 840 841 842 843
/* * 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.
844 845 846
 *
 * We ignore all bits for sectors that end earlier than 'start'.
 * This is used when reading an out-of-date bitmap...
847
 */
848
static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
849 850 851 852 853 854 855 856
{
	unsigned long i, chunks, index, oldindex, bit;
	struct page *page = NULL, *oldpage = NULL;
	unsigned long num_pages, bit_cnt = 0;
	struct file *file;
	unsigned long bytes, offset, dummy;
	int outofdate;
	int ret = -ENOSPC;
857
	void *paddr;
858 859 860 861

	chunks = bitmap->chunks;
	file = bitmap->file;

862
	BUG_ON(!file && !bitmap->offset);
863

864
#ifdef INJECT_FAULTS_3
865 866 867 868 869 870 871 872 873
	outofdate = 1;
#else
	outofdate = bitmap->flags & BITMAP_STALE;
#endif
	if (outofdate)
		printk(KERN_INFO "%s: bitmap file is out of date, doing full "
			"recovery\n", bmname(bitmap));

	bytes = (chunks + 7) / 8;
874

875
	num_pages = (bytes + sizeof(bitmap_super_t) + PAGE_SIZE - 1) / PAGE_SIZE;
876

877
	if (file && i_size_read(file->f_mapping->host) < bytes + sizeof(bitmap_super_t)) {
878 879 880 881 882 883
		printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
			bmname(bitmap),
			(unsigned long) i_size_read(file->f_mapping->host),
			bytes + sizeof(bitmap_super_t));
		goto out;
	}
884 885 886

	ret = -ENOMEM;

887
	bitmap->filemap = kmalloc(sizeof(struct page *) * num_pages, GFP_KERNEL);
888
	if (!bitmap->filemap)
889 890
		goto out;

891
	bitmap->filemap_attr = kzalloc(sizeof(long) * num_pages, GFP_KERNEL);
892
	if (!bitmap->filemap_attr)
893 894 895 896 897
		goto out;

	oldindex = ~0L;

	for (i = 0; i < chunks; i++) {
898
		int b;
899 900 901 902 903 904 905 906 907 908 909 910
		index = file_page_index(i);
		bit = file_page_offset(i);
		if (index != oldindex) { /* this is a new page, read it in */
			/* unmap the old page, we're done with it */
			if (index == 0) {
				/*
				 * if we're here then the superblock page
				 * contains some bits (PAGE_SIZE != sizeof sb)
				 * we've already read it in, so just use it
				 */
				page = bitmap->sb_page;
				offset = sizeof(bitmap_super_t);
911
			} else if (file) {
912
				page = read_page(file, index, &dummy);
913 914 915
				offset = 0;
			} else {
				page = read_sb_page(bitmap->mddev, bitmap->offset, index);
916 917
				offset = 0;
			}
918 919 920 921 922
			if (IS_ERR(page)) { /* read error */
				ret = PTR_ERR(page);
				goto out;
			}

923 924 925 926 927 928 929 930
			oldindex = index;
			oldpage = page;

			if (outofdate) {
				/*
				 * if bitmap is out of date, dirty the
			 	 * whole page and write it out
				 */
931 932
				paddr = kmap_atomic(page, KM_USER0);
				memset(paddr + offset, 0xff,
933
				       PAGE_SIZE - offset);
934
				kunmap_atomic(paddr, KM_USER0);
935
				ret = write_page(bitmap, page, 1);
936 937
				if (ret) {
					/* release, page not in filemap yet */
938
					put_page(page);
939 940 941 942 943 944
					goto out;
				}
			}

			bitmap->filemap[bitmap->file_pages++] = page;
		}
945
		paddr = kmap_atomic(page, KM_USER0);
946
		if (bitmap->flags & BITMAP_HOSTENDIAN)
947
			b = test_bit(bit, paddr);
948
		else
949 950
			b = ext2_test_bit(bit, paddr);
		kunmap_atomic(paddr, KM_USER0);
951
		if (b) {
952
			/* if the disk bit is set, set the memory bit */
953 954 955
			bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap),
					       ((i+1) << (CHUNK_BLOCK_SHIFT(bitmap)) >= start)
				);
956
			bit_cnt++;
957
			set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977
		}
	}

 	/* everything went OK */
	ret = 0;
	bitmap_mask_state(bitmap, BITMAP_STALE, MASK_UNSET);

	if (bit_cnt) { /* Kick recovery if any bits were set */
		set_bit(MD_RECOVERY_NEEDED, &bitmap->mddev->recovery);
		md_wakeup_thread(bitmap->mddev->thread);
	}

out:
	printk(KERN_INFO "%s: bitmap initialized from disk: "
		"read %lu/%lu pages, set %lu bits, status: %d\n",
		bmname(bitmap), bitmap->file_pages, num_pages, bit_cnt, ret);

	return ret;
}

978 979 980 981 982 983 984 985 986 987 988 989 990
void bitmap_write_all(struct bitmap *bitmap)
{
	/* We don't actually write all bitmap blocks here,
	 * just flag them as needing to be written
	 */

	unsigned long chunks = bitmap->chunks;
	unsigned long bytes = (chunks+7)/8 + sizeof(bitmap_super_t);
	unsigned long num_pages = (bytes + PAGE_SIZE-1) / PAGE_SIZE;
	while (num_pages--)
		bitmap->filemap_attr[num_pages] |= BITMAP_PAGE_NEEDWRITE;
}

991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013

static void bitmap_count_page(struct bitmap *bitmap, sector_t offset, int inc)
{
	sector_t chunk = offset >> CHUNK_BLOCK_SHIFT(bitmap);
	unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
	bitmap->bp[page].count += inc;
/*
	if (page == 0) printk("count page 0, offset %llu: %d gives %d\n",
			      (unsigned long long)offset, inc, bitmap->bp[page].count);
*/
	bitmap_checkfree(bitmap, page);
}
static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
					    sector_t offset, int *blocks,
					    int create);

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

int bitmap_daemon_work(struct bitmap *bitmap)
{
1014
	unsigned long j;
1015 1016 1017 1018 1019
	unsigned long flags;
	struct page *page = NULL, *lastpage = NULL;
	int err = 0;
	int blocks;
	int attr;
1020
	void *paddr;
1021 1022 1023 1024 1025 1026 1027 1028 1029 1030

	if (bitmap == NULL)
		return 0;
	if (time_before(jiffies, bitmap->daemon_lastrun + bitmap->daemon_sleep*HZ))
		return 0;
	bitmap->daemon_lastrun = jiffies;

	for (j = 0; j < bitmap->chunks; j++) {
		bitmap_counter_t *bmc;
		spin_lock_irqsave(&bitmap->lock, flags);
1031
		if (!bitmap->filemap) {
1032 1033 1034 1035 1036 1037 1038 1039
			/* error or shutdown */
			spin_unlock_irqrestore(&bitmap->lock, flags);
			break;
		}

		page = filemap_get_page(bitmap, j);

		if (page != lastpage) {
1040 1041 1042
			/* skip this page unless it's marked as needing cleaning */
			if (!((attr=get_page_attr(bitmap, page)) & BITMAP_PAGE_CLEAN)) {
				if (attr & BITMAP_PAGE_NEEDWRITE) {
1043
					get_page(page);
1044 1045 1046 1047
					clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
				}
				spin_unlock_irqrestore(&bitmap->lock, flags);
				if (attr & BITMAP_PAGE_NEEDWRITE) {
1048 1049 1050 1051 1052 1053 1054
					switch (write_page(bitmap, page, 0)) {
					case -EAGAIN:
						set_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
						break;
					case 0:
						break;
					default:
1055
						bitmap_file_kick(bitmap);
1056
					}
1057
					put_page(page);
1058 1059 1060 1061
				}
				continue;
			}

1062
			/* grab the new page, sync and release the old */
1063
			get_page(page);
1064 1065 1066 1067
			if (lastpage != NULL) {
				if (get_page_attr(bitmap, lastpage) & BITMAP_PAGE_NEEDWRITE) {
					clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
					spin_unlock_irqrestore(&bitmap->lock, flags);
1068
					err = write_page(bitmap, lastpage, 0);
1069 1070 1071 1072
					if (err == -EAGAIN) {
						err = 0;
						set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
					}
1073 1074 1075 1076
				} else {
					set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
					spin_unlock_irqrestore(&bitmap->lock, flags);
				}
1077
				put_page(lastpage);
1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104
				if (err)
					bitmap_file_kick(bitmap);
			} else
				spin_unlock_irqrestore(&bitmap->lock, flags);
			lastpage = page;
/*
			printk("bitmap clean at page %lu\n", j);
*/
			spin_lock_irqsave(&bitmap->lock, flags);
			clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
		}
		bmc = bitmap_get_counter(bitmap, j << CHUNK_BLOCK_SHIFT(bitmap),
					&blocks, 0);
		if (bmc) {
/*
  if (j < 100) printk("bitmap: j=%lu, *bmc = 0x%x\n", j, *bmc);
*/
			if (*bmc == 2) {
				*bmc=1; /* maybe clear the bit next time */
				set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
			} else if (*bmc == 1) {
				/* we can clear the bit */
				*bmc = 0;
				bitmap_count_page(bitmap, j << CHUNK_BLOCK_SHIFT(bitmap),
						  -1);

				/* clear the bit */
1105
				paddr = kmap_atomic(page, KM_USER0);
1106
				if (bitmap->flags & BITMAP_HOSTENDIAN)
1107
					clear_bit(file_page_offset(j), paddr);
1108
				else
1109 1110
					ext2_clear_bit(file_page_offset(j), paddr);
				kunmap_atomic(paddr, KM_USER0);
1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121
			}
		}
		spin_unlock_irqrestore(&bitmap->lock, flags);
	}

	/* now sync the final page */
	if (lastpage != NULL) {
		spin_lock_irqsave(&bitmap->lock, flags);
		if (get_page_attr(bitmap, lastpage) &BITMAP_PAGE_NEEDWRITE) {
			clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
			spin_unlock_irqrestore(&bitmap->lock, flags);
1122
			err = write_page(bitmap, lastpage, 0);
1123 1124 1125 1126
			if (err == -EAGAIN) {
				set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
				err = 0;
			}
1127 1128 1129 1130 1131
		} else {
			set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
			spin_unlock_irqrestore(&bitmap->lock, flags);
		}

1132
		put_page(lastpage);
1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161
	}

	return err;
}

static void daemon_exit(struct bitmap *bitmap, mdk_thread_t **daemon)
{
	mdk_thread_t *dmn;
	unsigned long flags;

	/* if no one is waiting on us, we'll free the md thread struct
	 * and exit, otherwise we let the waiter clean things up */
	spin_lock_irqsave(&bitmap->lock, flags);
	if ((dmn = *daemon)) { /* no one is waiting, cleanup and exit */
		*daemon = NULL;
		spin_unlock_irqrestore(&bitmap->lock, flags);
		kfree(dmn);
		complete_and_exit(NULL, 0); /* do_exit not exported */
	}
	spin_unlock_irqrestore(&bitmap->lock, flags);
}

static void bitmap_writeback_daemon(mddev_t *mddev)
{
	struct bitmap *bitmap = mddev->bitmap;
	struct page *page;
	struct page_list *item;
	int err = 0;

1162 1163 1164 1165 1166 1167 1168
	if (signal_pending(current)) {
		printk(KERN_INFO
		       "%s: bitmap writeback daemon got signal, exiting...\n",
		       bmname(bitmap));
		err = -EINTR;
		goto out;
	}
1169 1170 1171
	if (bitmap == NULL)
		/* about to be stopped. */
		return;
1172

1173 1174 1175 1176 1177 1178 1179 1180 1181 1182
	PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap));
	/* wait on bitmap page writebacks */
	while ((item = dequeue_page(bitmap))) {
		page = item->page;
		mempool_free(item, bitmap->write_pool);
		PRINTK("wait on page writeback: %p\n", page);
		wait_on_page_writeback(page);
		PRINTK("finished page writeback: %p\n", page);

		err = PageError(page);
1183
		put_page(page);
1184 1185 1186 1187 1188 1189
		if (err) {
			printk(KERN_WARNING "%s: bitmap file writeback "
			       "failed (page %lu): %d\n",
			       bmname(bitmap), page->index, err);
			bitmap_file_kick(bitmap);
			goto out;
1190 1191
		}
	}
1192 1193
 out:
	wake_up(&bitmap->write_wait);
1194 1195
	if (err) {
		printk(KERN_INFO "%s: bitmap writeback daemon exiting (%d)\n",
1196
		       bmname(bitmap), err);
1197 1198 1199 1200
		daemon_exit(bitmap, &bitmap->writeback_daemon);
	}
}

1201
static mdk_thread_t *bitmap_start_daemon(struct bitmap *bitmap,
1202 1203 1204 1205 1206
				void (*func)(mddev_t *), char *name)
{
	mdk_thread_t *daemon;
	char namebuf[32];

1207
#ifdef INJECT_FATAL_FAULT_2
1208 1209 1210 1211 1212 1213 1214 1215
	daemon = NULL;
#else
	sprintf(namebuf, "%%s_%s", name);
	daemon = md_register_thread(func, bitmap->mddev, namebuf);
#endif
	if (!daemon) {
		printk(KERN_ERR "%s: failed to start bitmap daemon\n",
			bmname(bitmap));
1216
		return ERR_PTR(-ECHILD);
1217 1218 1219 1220 1221
	}

	md_wakeup_thread(daemon); /* start it running */

	PRINTK("%s: %s daemon (pid %d) started...\n",
1222
		bmname(bitmap), name, daemon->tsk->pid);
1223

1224
	return daemon;
1225 1226
}

1227
static void bitmap_stop_daemon(struct bitmap *bitmap)
1228
{
1229 1230 1231 1232 1233
	/* the daemon can't stop itself... it'll just exit instead... */
	if (bitmap->writeback_daemon && ! IS_ERR(bitmap->writeback_daemon) &&
	    current->pid != bitmap->writeback_daemon->tsk->pid) {
		mdk_thread_t *daemon;
		unsigned long flags;
1234

1235 1236 1237 1238 1239 1240 1241
		spin_lock_irqsave(&bitmap->lock, flags);
		daemon = bitmap->writeback_daemon;
		bitmap->writeback_daemon = NULL;
		spin_unlock_irqrestore(&bitmap->lock, flags);
		if (daemon && ! IS_ERR(daemon))
			md_unregister_thread(daemon); /* destroy the thread */
	}
1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280
}

static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
					    sector_t offset, int *blocks,
					    int create)
{
	/* If 'create', we might release the lock and reclaim it.
	 * The lock must have been taken with interrupts enabled.
	 * If !create, we don't release the lock.
	 */
	sector_t chunk = offset >> CHUNK_BLOCK_SHIFT(bitmap);
	unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
	unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
	sector_t csize;

	if (bitmap_checkpage(bitmap, page, create) < 0) {
		csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap));
		*blocks = csize - (offset & (csize- 1));
		return NULL;
	}
	/* now locked ... */

	if (bitmap->bp[page].hijacked) { /* hijacked pointer */
		/* should we use the first or second counter field
		 * of the hijacked pointer? */
		int hi = (pageoff > PAGE_COUNTER_MASK);
		csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap) +
					  PAGE_COUNTER_SHIFT - 1);
		*blocks = csize - (offset & (csize- 1));
		return  &((bitmap_counter_t *)
			  &bitmap->bp[page].map)[hi];
	} else { /* page is allocated */
		csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap));
		*blocks = csize - (offset & (csize- 1));
		return (bitmap_counter_t *)
			&(bitmap->bp[page].map[pageoff]);
	}
}

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int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
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{
	if (!bitmap) return 0;
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	if (behind) {
		atomic_inc(&bitmap->behind_writes);
		PRINTK(KERN_DEBUG "inc write-behind count %d/%d\n",
		  atomic_read(&bitmap->behind_writes), bitmap->max_write_behind);
	}

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