Commit bc4ae27d authored by Omar Sandoval's avatar Omar Sandoval Committed by Linus Torvalds
Browse files

mm: split SWP_FILE into SWP_ACTIVATED and SWP_FS 

The SWP_FILE flag serves two purposes: to make swap_{read,write}page() go
through the filesystem, and to make swapoff() call ->swap_deactivate().
For Btrfs, we want the latter but not the former, so split this flag into
two.  This makes us always call ->swap_deactivate() if ->swap_activate()
succeeded, not just if it didn't add any swap extents itself.

This also resolves the issue of the very misleading name of SWP_FILE,
which is only used for swap files over NFS.

Link: http://lkml.kernel.org/r/6d63d8668c4287a4f6d203d65696e96f80abdfc7.1536704650.git.osandov@fb.com


Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 91cbacc3

include/linux/swap.h

+7 −6
Original line number Diff line number Diff line
@@ -167,13 +167,14 @@ enum { 
	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */

	SWP_CONTINUED	= (1 << 5),	/* swap_map has count continuation */

	SWP_BLKDEV	= (1 << 6),	/* its a block device */

	SWP_FILE	= (1 << 7),	/* set after swap_activate success */

	SWP_AREA_DISCARD = (1 << 8),	/* single-time swap area discards */

	SWP_PAGE_DISCARD = (1 << 9),	/* freed swap page-cluster discards */

	SWP_STABLE_WRITES = (1 << 10),	/* no overwrite PG_writeback pages */

	SWP_SYNCHRONOUS_IO = (1 << 11),	/* synchronous IO is efficient */

	SWP_ACTIVATED	= (1 << 7),	/* set after swap_activate success */

	SWP_FS		= (1 << 8),	/* swap file goes through fs */

	SWP_AREA_DISCARD = (1 << 9),	/* single-time swap area discards */

	SWP_PAGE_DISCARD = (1 << 10),	/* freed swap page-cluster discards */

	SWP_STABLE_WRITES = (1 << 11),	/* no overwrite PG_writeback pages */

	SWP_SYNCHRONOUS_IO = (1 << 12),	/* synchronous IO is efficient */

					/* add others here before... */

	SWP_SCANNING	= (1 << 12),	/* refcount in scan_swap_map */

	SWP_SCANNING	= (1 << 13),	/* refcount in scan_swap_map */

};



#define SWAP_CLUSTER_MAX 32UL

mm/page_io.c

+3 −3
Original line number Diff line number Diff line
@@ -283,7 +283,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc, 
	struct swap_info_struct *sis = page_swap_info(page);



	VM_BUG_ON_PAGE(!PageSwapCache(page), page);

	if (sis->flags & SWP_FILE) {

	if (sis->flags & SWP_FS) {

		struct kiocb kiocb;

		struct file *swap_file = sis->swap_file;

		struct address_space *mapping = swap_file->f_mapping;
@@ -365,7 +365,7 @@ int swap_readpage(struct page *page, bool synchronous) 
		goto out;

	}



	if (sis->flags & SWP_FILE) {

	if (sis->flags & SWP_FS) {

		struct file *swap_file = sis->swap_file;

		struct address_space *mapping = swap_file->f_mapping;
@@ -423,7 +423,7 @@ int swap_set_page_dirty(struct page *page) 
{

	struct swap_info_struct *sis = page_swap_info(page);



	if (sis->flags & SWP_FILE) {

	if (sis->flags & SWP_FS) {

		struct address_space *mapping = sis->swap_file->f_mapping;



		VM_BUG_ON_PAGE(!PageSwapCache(page), page);

mm/swapfile.c

+8 −5
Original line number Diff line number Diff line
@@ -1003,7 +1003,7 @@ start_over: 
			goto nextsi;

		}

		if (size == SWAPFILE_CLUSTER) {

			if (!(si->flags & SWP_FILE))

			if (!(si->flags & SWP_FS))

				n_ret = swap_alloc_cluster(si, swp_entries);

		} else

			n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE,
@@ -2299,11 +2299,12 @@ static void destroy_swap_extents(struct swap_info_struct *sis) 
		kfree(se);

	}



	if (sis->flags & SWP_FILE) {

	if (sis->flags & SWP_ACTIVATED) {

		struct file *swap_file = sis->swap_file;

		struct address_space *mapping = swap_file->f_mapping;



		sis->flags &= ~SWP_FILE;

		sis->flags &= ~SWP_ACTIVATED;

		if (mapping->a_ops->swap_deactivate)

			mapping->a_ops->swap_deactivate(swap_file);

	}

}
@@ -2400,8 +2401,10 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) 


	if (mapping->a_ops->swap_activate) {

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

		if (ret >= 0)

			sis->flags |= SWP_ACTIVATED;

		if (!ret) {

			sis->flags |= SWP_FILE;

			sis->flags |= SWP_FS;

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

			*span = sis->pages;

		}

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