xfs_buf.c

LINUX 2.6.17.4的源码

submit_io:
	if (likely(bio->bi_size)) {
		submit_bio(rw, bio);
		if (size)
			goto next_chunk;
	} else {
		bio_put(bio);
		xfs_buf_ioerror(bp, EIO);
	}
}

int
xfs_buf_iorequest(
	xfs_buf_t		*bp)
{
	XB_TRACE(bp, "iorequest", 0);

	if (bp->b_flags & XBF_DELWRI) {
		xfs_buf_delwri_queue(bp, 1);
		return 0;
	}

	if (bp->b_flags & XBF_WRITE) {
		xfs_buf_wait_unpin(bp);
	}

	xfs_buf_hold(bp);

	/* Set the count to 1 initially, this will stop an I/O
	 * completion callout which happens before we have started
	 * all the I/O from calling xfs_buf_ioend too early.
	 */
	atomic_set(&bp->b_io_remaining, 1);
	_xfs_buf_ioapply(bp);
	_xfs_buf_ioend(bp, 0);

	xfs_buf_rele(bp);
	return 0;
}

/*
 *	Waits for I/O to complete on the buffer supplied.
 *	It returns immediately if no I/O is pending.
 *	It returns the I/O error code, if any, or 0 if there was no error.
 */
int
xfs_buf_iowait(
	xfs_buf_t		*bp)
{
	XB_TRACE(bp, "iowait", 0);
	if (atomic_read(&bp->b_io_remaining))
		blk_run_address_space(bp->b_target->bt_mapping);
	down(&bp->b_iodonesema);
	XB_TRACE(bp, "iowaited", (long)bp->b_error);
	return bp->b_error;
}

xfs_caddr_t
xfs_buf_offset(
	xfs_buf_t		*bp,
	size_t			offset)
{
	struct page		*page;

	if (bp->b_flags & XBF_MAPPED)
		return XFS_BUF_PTR(bp) + offset;

	offset += bp->b_offset;
	page = bp->b_pages[offset >> PAGE_CACHE_SHIFT];
	return (xfs_caddr_t)page_address(page) + (offset & (PAGE_CACHE_SIZE-1));
}

/*
 *	Move data into or out of a buffer.
 */
void
xfs_buf_iomove(
	xfs_buf_t		*bp,	/* buffer to process		*/
	size_t			boff,	/* starting buffer offset	*/
	size_t			bsize,	/* length to copy		*/
	caddr_t			data,	/* data address			*/
	xfs_buf_rw_t		mode)	/* read/write/zero flag		*/
{
	size_t			bend, cpoff, csize;
	struct page		*page;

	bend = boff + bsize;
	while (boff < bend) {
		page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
		cpoff = xfs_buf_poff(boff + bp->b_offset);
		csize = min_t(size_t,
			      PAGE_CACHE_SIZE-cpoff, bp->b_count_desired-boff);

		ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE));

		switch (mode) {
		case XBRW_ZERO:
			memset(page_address(page) + cpoff, 0, csize);
			break;
		case XBRW_READ:
			memcpy(data, page_address(page) + cpoff, csize);
			break;
		case XBRW_WRITE:
			memcpy(page_address(page) + cpoff, data, csize);
		}

		boff += csize;
		data += csize;
	}
}

/*
 *	Handling of buffer targets (buftargs).
 */

/*
 *	Wait for any bufs with callbacks that have been submitted but
 *	have not yet returned... walk the hash list for the target.
 */
void
xfs_wait_buftarg(
	xfs_buftarg_t	*btp)
{
	xfs_buf_t	*bp, *n;
	xfs_bufhash_t	*hash;
	uint		i;

	for (i = 0; i < (1 << btp->bt_hashshift); i++) {
		hash = &btp->bt_hash[i];
again:
		spin_lock(&hash->bh_lock);
		list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
			ASSERT(btp == bp->b_target);
			if (!(bp->b_flags & XBF_FS_MANAGED)) {
				spin_unlock(&hash->bh_lock);
				/*
				 * Catch superblock reference count leaks
				 * immediately
				 */
				BUG_ON(bp->b_bn == 0);
				delay(100);
				goto again;
			}
		}
		spin_unlock(&hash->bh_lock);
	}
}

/*
 *	Allocate buffer hash table for a given target.
 *	For devices containing metadata (i.e. not the log/realtime devices)
 *	we need to allocate a much larger hash table.
 */
STATIC void
xfs_alloc_bufhash(
	xfs_buftarg_t		*btp,
	int			external)
{
	unsigned int		i;

	btp->bt_hashshift = external ? 3 : 8;	/* 8 or 256 buckets */
	btp->bt_hashmask = (1 << btp->bt_hashshift) - 1;
	btp->bt_hash = kmem_zalloc((1 << btp->bt_hashshift) *
					sizeof(xfs_bufhash_t), KM_SLEEP);
	for (i = 0; i < (1 << btp->bt_hashshift); i++) {
		spin_lock_init(&btp->bt_hash[i].bh_lock);
		INIT_LIST_HEAD(&btp->bt_hash[i].bh_list);
	}
}

STATIC void
xfs_free_bufhash(
	xfs_buftarg_t		*btp)
{
	kmem_free(btp->bt_hash, (1<<btp->bt_hashshift) * sizeof(xfs_bufhash_t));
	btp->bt_hash = NULL;
}

/*
 *	buftarg list for delwrite queue processing
 */
STATIC LIST_HEAD(xfs_buftarg_list);
STATIC DEFINE_SPINLOCK(xfs_buftarg_lock);

STATIC void
xfs_register_buftarg(
	xfs_buftarg_t           *btp)
{
	spin_lock(&xfs_buftarg_lock);
	list_add(&btp->bt_list, &xfs_buftarg_list);
	spin_unlock(&xfs_buftarg_lock);
}

STATIC void
xfs_unregister_buftarg(
	xfs_buftarg_t           *btp)
{
	spin_lock(&xfs_buftarg_lock);
	list_del(&btp->bt_list);
	spin_unlock(&xfs_buftarg_lock);
}

void
xfs_free_buftarg(
	xfs_buftarg_t		*btp,
	int			external)
{
	xfs_flush_buftarg(btp, 1);
	if (external)
		xfs_blkdev_put(btp->bt_bdev);
	xfs_free_bufhash(btp);
	iput(btp->bt_mapping->host);

	/* Unregister the buftarg first so that we don't get a
	 * wakeup finding a non-existent task
	 */
	xfs_unregister_buftarg(btp);
	kthread_stop(btp->bt_task);

	kmem_free(btp, sizeof(*btp));
}

STATIC int
xfs_setsize_buftarg_flags(
	xfs_buftarg_t		*btp,
	unsigned int		blocksize,
	unsigned int		sectorsize,
	int			verbose)
{
	btp->bt_bsize = blocksize;
	btp->bt_sshift = ffs(sectorsize) - 1;
	btp->bt_smask = sectorsize - 1;

	if (set_blocksize(btp->bt_bdev, sectorsize)) {
		printk(KERN_WARNING
			"XFS: Cannot set_blocksize to %u on device %s\n",
			sectorsize, XFS_BUFTARG_NAME(btp));
		return EINVAL;
	}

	if (verbose &&
	    (PAGE_CACHE_SIZE / BITS_PER_LONG) > sectorsize) {
		printk(KERN_WARNING
			"XFS: %u byte sectors in use on device %s.  "
			"This is suboptimal; %u or greater is ideal.\n",
			sectorsize, XFS_BUFTARG_NAME(btp),
			(unsigned int)PAGE_CACHE_SIZE / BITS_PER_LONG);
	}

	return 0;
}

/*
 *	When allocating the initial buffer target we have not yet
 *	read in the superblock, so don't know what sized sectors
 *	are being used is at this early stage.  Play safe.
 */
STATIC int
xfs_setsize_buftarg_early(
	xfs_buftarg_t		*btp,
	struct block_device	*bdev)
{
	return xfs_setsize_buftarg_flags(btp,
			PAGE_CACHE_SIZE, bdev_hardsect_size(bdev), 0);
}

int
xfs_setsize_buftarg(
	xfs_buftarg_t		*btp,
	unsigned int		blocksize,
	unsigned int		sectorsize)
{
	return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
}

STATIC int
xfs_mapping_buftarg(
	xfs_buftarg_t		*btp,
	struct block_device	*bdev)
{
	struct backing_dev_info	*bdi;
	struct inode		*inode;
	struct address_space	*mapping;
	static struct address_space_operations mapping_aops = {
		.sync_page = block_sync_page,
		.migratepage = fail_migrate_page,
	};

	inode = new_inode(bdev->bd_inode->i_sb);
	if (!inode) {
		printk(KERN_WARNING
			"XFS: Cannot allocate mapping inode for device %s\n",
			XFS_BUFTARG_NAME(btp));
		return ENOMEM;
	}
	inode->i_mode = S_IFBLK;
	inode->i_bdev = bdev;
	inode->i_rdev = bdev->bd_dev;
	bdi = blk_get_backing_dev_info(bdev);
	if (!bdi)
		bdi = &default_backing_dev_info;
	mapping = &inode->i_data;
	mapping->a_ops = &mapping_aops;
	mapping->backing_dev_info = bdi;
	mapping_set_gfp_mask(mapping, GFP_NOFS);
	btp->bt_mapping = mapping;
	return 0;
}

STATIC int
xfs_alloc_delwrite_queue(
	xfs_buftarg_t		*btp)
{
	int	error = 0;

	INIT_LIST_HEAD(&btp->bt_list);
	INIT_LIST_HEAD(&btp->bt_delwrite_queue);
	spinlock_init(&btp->bt_delwrite_lock, "delwri_lock");
	btp->bt_flags = 0;
	btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd");
	if (IS_ERR(btp->bt_task)) {
		error = PTR_ERR(btp->bt_task);
		goto out_error;
	}
	xfs_register_buftarg(btp);
out_error:
	return error;
}

xfs_buftarg_t *
xfs_alloc_buftarg(
	struct block_device	*bdev,
	int			external)
{
	xfs_buftarg_t		*btp;

	btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);

	btp->bt_dev =  bdev->bd_dev;
	btp->bt_bdev = bdev;
	if (xfs_setsize_buftarg_early(btp, bdev))
		goto error;
	if (xfs_mapping_buftarg(btp, bdev))
		goto error;
	if (xfs_alloc_delwrite_queue(btp))
		goto error;
	xfs_alloc_bufhash(btp, external);
	return btp;

error:
	kmem_free(btp, sizeof(*btp));
	return NULL;
}


/*
 *	Delayed write buffer handling
 */
STATIC void
xfs_buf_delwri_queue(
	xfs_buf_t		*bp,
	int			unlock)
{
	struct list_head	*dwq = &bp->b_target->bt_delwrite_queue;
	spinlock_t		*dwlk = &bp->b_target->bt_delwrite_lock;

	XB_TRACE(bp, "delwri_q", (long)unlock);
	ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));

	spin_lock(dwlk);
	/* If already in the queue, dequeue and place at tail */
	if (!list_empty(&bp->b_list)) {
		ASSERT(bp->b_flags & _XBF_DELWRI_Q);
		if (unlock)
			atomic_dec(&bp->b_hold);
		list_del(&bp->b_list);
	}

	bp->b_flags |= _XBF_DELWRI_Q;
	list_add_tail(&bp->b_list, dwq);
	bp->b_queuetime = jiffies;
	spin_unlock(dwlk);

	if (unlock)
		xfs_buf_unlock(bp);
}

void
xfs_buf_delwri_dequeue(
	xfs_buf_t		*bp)
{
	spinlock_t		*dwlk = &bp->b_target->bt_delwrite_lock;
	int			dequeued = 0;

	spin_lock(dwlk);
	if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
		ASSERT(bp->b_flags & _XBF_DELWRI_Q);
		list_del_init(&bp->b_list);
		dequeued = 1;
	}
	bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
	spin_unlock(dwlk);

	if (dequeued)
		xfs_buf_rele(bp);

	XB_TRACE(bp, "delwri_dq", (long)dequeued);
}

STATIC void
xfs_buf_runall_queues(
	struct workqueue_struct	*queue)
{
	flush_workqueue(queue);
}

STATIC int
xfsbufd_wakeup(
	int			priority,
	gfp_t			mask)
{
	xfs_buftarg_t		*btp;

	spin_lock(&xfs_buftarg_lock);
	list_for_each_entry(btp, &xfs_buftarg_list, bt_list) {
		if (test_bit(XBT_FORCE_SLEEP, &btp->bt_flags))
			continue;
		set_bit(XBT_FORCE_FLUSH, &btp->bt_flags);
		wake_up_process(btp->bt_task);
	}
	spin_unlock(&xfs_buftarg_lock);
	return 0;
}

STATIC int
xfsbufd(
	void			*data)
{
	struct list_head	tmp;
	unsigned long		age;
	xfs_buftarg_t		*target = (xfs_buftarg_t *)data;
	xfs_buf_t		*bp, *n;
	struct list_head	*dwq = &target->bt_delwrite_queue;
	spinlock_t		*dwlk = &target->bt_delwrite_lock;

	current->flags |= PF_MEMALLOC;

	INIT_LIST_HEAD(&tmp);
	do {
		if (unlikely(freezing(current))) {
			set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
			refrigerator();
		} else {
			clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
		}

		schedule_timeout_interruptible(
			xfs_buf_timer_centisecs * msecs_to_jiffies(10));

		age = xfs_buf_age_centisecs * msecs_to_jiffies(10);
		spin_lock(dwlk);
		list_for_each_entry_safe(bp, n, dwq, b_list) {
			XB_TRACE(bp, "walkq1", (long)xfs_buf_ispin(bp));
			ASSERT(bp->b_flags & XBF_DELWRI);

			if (!xfs_buf_ispin(bp) && !xfs_buf_cond_lock(bp)) {
				if (!test_bit(XBT_FORCE_FLUSH,
						&target->bt_flags) &&
				    time_before(jiffies,
						bp->b_queuetime + age)) {
					xfs_buf_unlock(bp);
					break;
				}

				bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
				bp->b_flags |= XBF_WRITE;
				list_move(&bp->b_list, &tmp);
			}
		}
		spin_unlock(dwlk);

		while (!list_empty(&tmp)) {
			bp = list_entry(tmp.next, xfs_buf_t, b_list);
			ASSERT(target == bp->b_target);

			list_del_init(&bp->b_list);
			xfs_buf_iostrategy(bp);

			blk_run_address_space(target->bt_mapping);
		}

		if (as_list_len > 0)
			purge_addresses();

		clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
	} while (!kthread_should_stop());

	return 0;
}

/*
 *	Go through all incore buffers, and release buffers if they belong to
 *	the given device. This is used in filesystem error handling to
 *	preserve the consistency of its metadata.
 */
int
xfs_flush_buftarg(
	xfs_buftarg_t		*target,
	int			wait)
{
	struct list_head	tmp;
	xfs_buf_t		*bp, *n;
	int			pincount = 0;
	struct list_head	*dwq = &target->bt_delwrite_queue;
	spinlock_t		*dwlk = &target->bt_delwrite_lock;

	xfs_buf_runall_queues(xfsdatad_workqueue);
	xfs_buf_runall_queues(xfslogd_workqueue);

	INIT_LIST_HEAD(&tmp);
	spin_lock(dwlk);
	list_for_each_entry_safe(bp, n, dwq, b_list) {
		ASSERT(bp->b_target == target);
		ASSERT(bp->b_flags & (XBF_DELWRI | _XBF_DELWRI_Q));
		XB_TRACE(bp, "walkq2", (long)xfs_buf_ispin(bp));
		if (xfs_buf_ispin(bp)) {
			pincount++;
			continue;
		}

		list_move(&bp->b_list, &tmp);
	}
	spin_unlock(dwlk);

	/*
	 * Dropped the delayed write list lock, now walk the temporary list
	 */
	list_for_each_entry_safe(bp, n, &tmp, b_list) {
		xfs_buf_lock(bp);
		bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
		bp->b_flags |= XBF_WRITE;
		if (wait)
			bp->b_flags &= ~XBF_ASYNC;
		else
			list_del_init(&bp->b_list);

		xfs_buf_iostrategy(bp);
	}

	/*
	 * Remaining list items must be flushed before returning
	 */
	while (!list_empty(&tmp)) {
		bp = list_entry(tmp.next, xfs_buf_t, b_list);

		list_del_init(&bp->b_list);
		xfs_iowait(bp);
		xfs_buf_relse(bp);
	}

	if (wait)
		blk_run_address_space(target->bt_mapping);

	return pincount;
}

int __init
xfs_buf_init(void)
{
#ifdef XFS_BUF_TRACE
	xfs_buf_trace_buf = ktrace_alloc(XFS_BUF_TRACE_SIZE, KM_SLEEP);
#endif

	xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
						KM_ZONE_HWALIGN, NULL);
	if (!xfs_buf_zone)
		goto out_free_trace_buf;

	xfslogd_workqueue = create_workqueue("xfslogd");
	if (!xfslogd_workqueue)
		goto out_free_buf_zone;

	xfsdatad_workqueue = create_workqueue("xfsdatad");
	if (!xfsdatad_workqueue)
		goto out_destroy_xfslogd_workqueue;

	xfs_buf_shake = kmem_shake_register(xfsbufd_wakeup);
	if (!xfs_buf_shake)
		goto out_destroy_xfsdatad_workqueue;

	return 0;

 out_destroy_xfsdatad_workqueue:
	destroy_workqueue(xfsdatad_workqueue);
 out_destroy_xfslogd_workqueue:
	destroy_workqueue(xfslogd_workqueue);
 out_free_buf_zone:
	kmem_zone_destroy(xfs_buf_zone);
 out_free_trace_buf:
#ifdef XFS_BUF_TRACE
	ktrace_free(xfs_buf_trace_buf);
#endif
	return -ENOMEM;
}

void
xfs_buf_terminate(void)
{
	kmem_shake_deregister(xfs_buf_shake);
	destroy_workqueue(xfsdatad_workqueue);
	destroy_workqueue(xfslogd_workqueue);
	kmem_zone_destroy(xfs_buf_zone);
#ifdef XFS_BUF_TRACE
	ktrace_free(xfs_buf_trace_buf);
#endif
}