Commit 9625a5f2 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

swap_info: include first_swap_extent 



Make better use of the space by folding first swap_extent into its
swap_info_struct, instead of just the list_head: swap partitions need
only that one, and for others it's used as a circular list anyway.

[jirislaby@gmail.com: fix crash on double swapon]
Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: default avatarJiri Slaby <jirislaby@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent efa90a98

include/linux/swap.h

+1 −1
Original line number Diff line number Diff line
@@ -165,7 +165,7 @@ struct swap_info_struct { 
	signed char	next;		/* next type on the swap list */

	struct file *swap_file;

	struct block_device *bdev;

	struct list_head extent_list;

	struct swap_extent first_swap_extent;

	struct swap_extent *curr_swap_extent;

	unsigned short *swap_map;

	unsigned int lowest_bit;

mm/swapfile.c

+36 −34
Original line number Diff line number Diff line
@@ -145,23 +145,28 @@ void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) 
static int discard_swap(struct swap_info_struct *si)

{

	struct swap_extent *se;

	sector_t start_block;

	sector_t nr_blocks;

	int err = 0;



	list_for_each_entry(se, &si->extent_list, list) {

		sector_t start_block = se->start_block << (PAGE_SHIFT - 9);

		sector_t nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);



		if (se->start_page == 0) {

	/* Do not discard the swap header page! */

			start_block += 1 << (PAGE_SHIFT - 9);

			nr_blocks -= 1 << (PAGE_SHIFT - 9);

			if (!nr_blocks)

				continue;

	se = &si->first_swap_extent;

	start_block = (se->start_block + 1) << (PAGE_SHIFT - 9);

	nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);

	if (nr_blocks) {

		err = blkdev_issue_discard(si->bdev, start_block,

				nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER);

		if (err)

			return err;

		cond_resched();

	}



	list_for_each_entry(se, &si->first_swap_extent.list, list) {

		start_block = se->start_block << (PAGE_SHIFT - 9);

		nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);



		err = blkdev_issue_discard(si->bdev, start_block,

						nr_blocks, GFP_KERNEL,

						DISCARD_FL_BARRIER);

				nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER);

		if (err)

			break;
@@ -200,14 +205,11 @@ static void discard_swap_cluster(struct swap_info_struct *si, 
			start_block <<= PAGE_SHIFT - 9;

			nr_blocks <<= PAGE_SHIFT - 9;

			if (blkdev_issue_discard(si->bdev, start_block,

							nr_blocks, GFP_NOIO,

							DISCARD_FL_BARRIER))

				    nr_blocks, GFP_NOIO, DISCARD_FL_BARRIER))

				break;

		}



		lh = se->list.next;

		if (lh == &si->extent_list)

			lh = lh->next;

		se = list_entry(lh, struct swap_extent, list);

	}

}
@@ -761,10 +763,8 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) 
			return type;

		}

		if (bdev == sis->bdev) {

			struct swap_extent *se;

			struct swap_extent *se = &sis->first_swap_extent;



			se = list_entry(sis->extent_list.next,

					struct swap_extent, list);

			if (se->start_block == offset) {

				if (bdev_p)

					*bdev_p = bdgrab(sis->bdev);
@@ -1310,8 +1310,6 @@ sector_t map_swap_page(swp_entry_t entry, struct block_device **bdev) 
			return se->start_block + (offset - se->start_page);

		}

		lh = se->list.next;

		if (lh == &sis->extent_list)

			lh = lh->next;

		se = list_entry(lh, struct swap_extent, list);

		sis->curr_swap_extent = se;

		BUG_ON(se == start_se);		/* It *must* be present */
@@ -1340,10 +1338,10 @@ sector_t swapdev_block(int type, pgoff_t offset) 
 */

static void destroy_swap_extents(struct swap_info_struct *sis)

{

	while (!list_empty(&sis->extent_list)) {

	while (!list_empty(&sis->first_swap_extent.list)) {

		struct swap_extent *se;



		se = list_entry(sis->extent_list.next,

		se = list_entry(sis->first_swap_extent.list.next,

				struct swap_extent, list);

		list_del(&se->list);

		kfree(se);
@@ -1364,8 +1362,15 @@ add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 
	struct swap_extent *new_se;

	struct list_head *lh;



	lh = sis->extent_list.prev;	/* The highest page extent */

	if (lh != &sis->extent_list) {

	if (start_page == 0) {

		se = &sis->first_swap_extent;

		sis->curr_swap_extent = se;

		se->start_page = 0;

		se->nr_pages = nr_pages;

		se->start_block = start_block;

		return 1;

	} else {

		lh = sis->first_swap_extent.list.prev;	/* Highest extent */

		se = list_entry(lh, struct swap_extent, list);

		BUG_ON(se->start_page + se->nr_pages != start_page);

		if (se->start_block + se->nr_pages == start_block) {
@@ -1385,7 +1390,7 @@ add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 
	new_se->nr_pages = nr_pages;

	new_se->start_block = start_block;



	list_add_tail(&new_se->list, &sis->extent_list);

	list_add_tail(&new_se->list, &sis->first_swap_extent.list);

	return 1;

}
@@ -1437,7 +1442,7 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) 
	if (S_ISBLK(inode->i_mode)) {

		ret = add_swap_extent(sis, 0, sis->max, 0);

		*span = sis->pages;

		goto done;

		goto out;

	}



	blkbits = inode->i_blkbits;
@@ -1508,15 +1513,12 @@ reprobe: 
	sis->max = page_no;

	sis->pages = page_no - 1;

	sis->highest_bit = page_no - 1;

done:

	sis->curr_swap_extent = list_entry(sis->extent_list.prev,

					struct swap_extent, list);

	goto out;

out:

	return ret;

bad_bmap:

	printk(KERN_ERR "swapon: swapfile has holes\n");

	ret = -EINVAL;

out:

	return ret;

	goto out;

}



SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
@@ -1815,7 +1817,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) 
		kfree(p);

		goto out;

	}

	INIT_LIST_HEAD(&p->extent_list);

	if (type >= nr_swapfiles) {

		p->type = type;

		swap_info[type] = p;
@@ -1834,6 +1835,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) 
		 * would be relying on p->type to remain valid.

		 */

	}

	INIT_LIST_HEAD(&p->first_swap_extent.list);

	p->flags = SWP_USED;

	p->next = -1;

	spin_unlock(&swap_lock);

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