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Commit a509bc1a authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm: swap: implement generic handler for swap_activate 



The version of swap_activate introduced is sufficient for swap-over-NFS
but would not provide enough information to implement a generic handler.
This patch shuffles things slightly to ensure the same information is
available for aops->swap_activate() as is available to the core.

No functionality change.

Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 62c230bc

include/linux/fs.h

+4 −2
Original line number Diff line number Diff line
@@ -429,6 +429,7 @@ struct kstatfs; 
struct vm_area_struct;

struct vfsmount;

struct cred;

struct swap_info_struct;



extern void __init inode_init(void);

extern void __init inode_init_early(void);
@@ -640,8 +641,9 @@ struct address_space_operations { 
	int (*error_remove_page)(struct address_space *, struct page *);



	/* swapfile support */

	int (*swap_activate)(struct file *file);

	int (*swap_deactivate)(struct file *file);

	int (*swap_activate)(struct swap_info_struct *sis, struct file *file,

				sector_t *span);

	void (*swap_deactivate)(struct file *file);

};



extern const struct address_space_operations empty_aops;

include/linux/swap.h

+5 −0
Original line number Diff line number Diff line
@@ -324,6 +324,11 @@ extern int swap_writepage(struct page *page, struct writeback_control *wbc); 
extern int swap_set_page_dirty(struct page *page);

extern void end_swap_bio_read(struct bio *bio, int err);



int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,

		unsigned long nr_pages, sector_t start_block);

int generic_swapfile_activate(struct swap_info_struct *, struct file *,

		sector_t *);



/* linux/mm/swap_state.c */

extern struct address_space swapper_space;

#define total_swapcache_pages  swapper_space.nrpages

mm/page_io.c

+92 −0
Original line number Diff line number Diff line
@@ -87,6 +87,98 @@ void end_swap_bio_read(struct bio *bio, int err) 
	bio_put(bio);

}



int generic_swapfile_activate(struct swap_info_struct *sis,

				struct file *swap_file,

				sector_t *span)

{

	struct address_space *mapping = swap_file->f_mapping;

	struct inode *inode = mapping->host;

	unsigned blocks_per_page;

	unsigned long page_no;

	unsigned blkbits;

	sector_t probe_block;

	sector_t last_block;

	sector_t lowest_block = -1;

	sector_t highest_block = 0;

	int nr_extents = 0;

	int ret;



	blkbits = inode->i_blkbits;

	blocks_per_page = PAGE_SIZE >> blkbits;



	/*

	 * Map all the blocks into the extent list.  This code doesn't try

	 * to be very smart.

	 */

	probe_block = 0;

	page_no = 0;

	last_block = i_size_read(inode) >> blkbits;

	while ((probe_block + blocks_per_page) <= last_block &&

			page_no < sis->max) {

		unsigned block_in_page;

		sector_t first_block;



		first_block = bmap(inode, probe_block);

		if (first_block == 0)

			goto bad_bmap;



		/*

		 * It must be PAGE_SIZE aligned on-disk

		 */

		if (first_block & (blocks_per_page - 1)) {

			probe_block++;

			goto reprobe;

		}



		for (block_in_page = 1; block_in_page < blocks_per_page;

					block_in_page++) {

			sector_t block;



			block = bmap(inode, probe_block + block_in_page);

			if (block == 0)

				goto bad_bmap;

			if (block != first_block + block_in_page) {

				/* Discontiguity */

				probe_block++;

				goto reprobe;

			}

		}



		first_block >>= (PAGE_SHIFT - blkbits);

		if (page_no) {	/* exclude the header page */

			if (first_block < lowest_block)

				lowest_block = first_block;

			if (first_block > highest_block)

				highest_block = first_block;

		}



		/*

		 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks

		 */

		ret = add_swap_extent(sis, page_no, 1, first_block);

		if (ret < 0)

			goto out;

		nr_extents += ret;

		page_no++;

		probe_block += blocks_per_page;

reprobe:

		continue;

	}

	ret = nr_extents;

	*span = 1 + highest_block - lowest_block;

	if (page_no == 0)

		page_no = 1;	/* force Empty message */

	sis->max = page_no;

	sis->pages = page_no - 1;

	sis->highest_bit = page_no - 1;

out:

	return ret;

bad_bmap:

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

	ret = -EINVAL;

	goto out;

}



/*

 * We may have stale swap cache pages in memory: notice

 * them here and get rid of the unnecessary final write.

mm/swapfile.c

+5 −86
Original line number Diff line number Diff line
@@ -1345,7 +1345,7 @@ static void destroy_swap_extents(struct swap_info_struct *sis) 
 *

 * This function rather assumes that it is called in ascending page order.

 */

static int

int

add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,

		unsigned long nr_pages, sector_t start_block)

{
@@ -1421,106 +1421,25 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) 
	struct file *swap_file = sis->swap_file;

	struct address_space *mapping = swap_file->f_mapping;

	struct inode *inode = mapping->host;

	unsigned blocks_per_page;

	unsigned long page_no;

	unsigned blkbits;

	sector_t probe_block;

	sector_t last_block;

	sector_t lowest_block = -1;

	sector_t highest_block = 0;

	int nr_extents = 0;

	int ret;



	if (S_ISBLK(inode->i_mode)) {

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

		*span = sis->pages;

		goto out;

		return ret;

	}



	if (mapping->a_ops->swap_activate) {

		ret = mapping->a_ops->swap_activate(swap_file);

		ret = mapping->a_ops->swap_activate(sis, swap_file, span);

		if (!ret) {

			sis->flags |= SWP_FILE;

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

			*span = sis->pages;

		}

		goto out;

	}



	blkbits = inode->i_blkbits;

	blocks_per_page = PAGE_SIZE >> blkbits;



	/*

	 * Map all the blocks into the extent list.  This code doesn't try

	 * to be very smart.

	 */

	probe_block = 0;

	page_no = 0;

	last_block = i_size_read(inode) >> blkbits;

	while ((probe_block + blocks_per_page) <= last_block &&

			page_no < sis->max) {

		unsigned block_in_page;

		sector_t first_block;



		first_block = bmap(inode, probe_block);

		if (first_block == 0)

			goto bad_bmap;



		/*

		 * It must be PAGE_SIZE aligned on-disk

		 */

		if (first_block & (blocks_per_page - 1)) {

			probe_block++;

			goto reprobe;

		}



		for (block_in_page = 1; block_in_page < blocks_per_page;

					block_in_page++) {

			sector_t block;



			block = bmap(inode, probe_block + block_in_page);

			if (block == 0)

				goto bad_bmap;

			if (block != first_block + block_in_page) {

				/* Discontiguity */

				probe_block++;

				goto reprobe;

			}

		}



		first_block >>= (PAGE_SHIFT - blkbits);

		if (page_no) {	/* exclude the header page */

			if (first_block < lowest_block)

				lowest_block = first_block;

			if (first_block > highest_block)

				highest_block = first_block;

		return ret;

	}



		/*

		 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks

		 */

		ret = add_swap_extent(sis, page_no, 1, first_block);

		if (ret < 0)

			goto out;

		nr_extents += ret;

		page_no++;

		probe_block += blocks_per_page;

reprobe:

		continue;

	}

	ret = nr_extents;

	*span = 1 + highest_block - lowest_block;

	if (page_no == 0)

		page_no = 1;	/* force Empty message */

	sis->max = page_no;

	sis->pages = page_no - 1;

	sis->highest_bit = page_no - 1;

out:

	return ret;

bad_bmap:

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

	ret = -EINVAL;

	goto out;

	return generic_swapfile_activate(sis, swap_file, span);

}



static void enable_swap_info(struct swap_info_struct *p, int prio,