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mm: split SWP_FILE into SWP_ACTIVATED and SWP_FS

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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: Omar Sandoval <osandov@fb.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Omar Sandoval 2018-10-26 15:10:51 -07:00 committed by Linus Torvalds
parent 91cbacc345
commit bc4ae27d81
3 changed files with 18 additions and 14 deletions
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13
include/linux/swap.h
View File

@ -167,13 +167,14 @@ enum {
SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */ SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */ SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
SWP_BLKDEV = (1 << 6), /* its a block device */ SWP_BLKDEV = (1 << 6), /* its a block device */
SWP_FILE = (1 << 7), /* set after swap_activate success */ SWP_ACTIVATED = (1 << 7), /* set after swap_activate success */
SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */ SWP_FS = (1 << 8), /* swap file goes through fs */
SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */ SWP_AREA_DISCARD = (1 << 9), /* single-time swap area discards */
SWP_STABLE_WRITES = (1 << 10), /* no overwrite PG_writeback pages */ SWP_PAGE_DISCARD = (1 << 10), /* freed swap page-cluster discards */
SWP_SYNCHRONOUS_IO = (1 << 11), /* synchronous IO is efficient */ SWP_STABLE_WRITES = (1 << 11), /* no overwrite PG_writeback pages */
SWP_SYNCHRONOUS_IO = (1 << 12), /* synchronous IO is efficient */
/* add others here before... */ /* 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 #define SWAP_CLUSTER_MAX 32UL

6
mm/page_io.c
View File

@ -283,7 +283,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
struct swap_info_struct *sis = page_swap_info(page); struct swap_info_struct *sis = page_swap_info(page);
VM_BUG_ON_PAGE(!PageSwapCache(page), page); VM_BUG_ON_PAGE(!PageSwapCache(page), page);
if (sis->flags & SWP_FILE) { if (sis->flags & SWP_FS) {
struct kiocb kiocb; struct kiocb kiocb;
struct file *swap_file = sis->swap_file; struct file *swap_file = sis->swap_file;
struct address_space *mapping = swap_file->f_mapping; struct address_space *mapping = swap_file->f_mapping;
@ -365,7 +365,7 @@ int swap_readpage(struct page *page, bool synchronous)
goto out; goto out;
} }
if (sis->flags & SWP_FILE) { if (sis->flags & SWP_FS) {
struct file *swap_file = sis->swap_file; struct file *swap_file = sis->swap_file;
struct address_space *mapping = swap_file->f_mapping; 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); 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; struct address_space *mapping = sis->swap_file->f_mapping;
VM_BUG_ON_PAGE(!PageSwapCache(page), page); VM_BUG_ON_PAGE(!PageSwapCache(page), page);

13
mm/swapfile.c
View File

@ -1003,7 +1003,7 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size)
goto nextsi; goto nextsi;
} }
if (size == SWAPFILE_CLUSTER) { if (size == SWAPFILE_CLUSTER) {
if (!(si->flags & SWP_FILE)) if (!(si->flags & SWP_FS))
n_ret = swap_alloc_cluster(si, swp_entries); n_ret = swap_alloc_cluster(si, swp_entries);
} else } else
n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE,
@ -2299,12 +2299,13 @@ static void destroy_swap_extents(struct swap_info_struct *sis)
kfree(se); kfree(se);
} }
if (sis->flags & SWP_FILE) { if (sis->flags & SWP_ACTIVATED) {
struct file *swap_file = sis->swap_file; struct file *swap_file = sis->swap_file;
struct address_space *mapping = swap_file->f_mapping; struct address_space *mapping = swap_file->f_mapping;
sis->flags &= ~SWP_FILE; sis->flags &= ~SWP_ACTIVATED;
mapping->a_ops->swap_deactivate(swap_file); 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) { if (mapping->a_ops->swap_activate) {
ret = mapping->a_ops->swap_activate(sis, swap_file, span); ret = mapping->a_ops->swap_activate(sis, swap_file, span);
if (ret >= 0)
sis->flags |= SWP_ACTIVATED;
if (!ret) { if (!ret) {
sis->flags |= SWP_FILE; sis->flags |= SWP_FS;
ret = add_swap_extent(sis, 0, sis->max, 0); ret = add_swap_extent(sis, 0, sis->max, 0);
*span = sis->pages; *span = sis->pages;
} }