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: 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>

1 files changed, 3 insertions, 3 deletions

diff --git a/mm/page_io.c b/mm/page_io.c
index 573d3663d846..a451ffa9491c 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -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);