From: Omar Sandoval <osandov@fb.com>
Date: Fri, 26 Oct 2018 15:10:51 -0700
Subject: mm: split SWP_FILE into SWP_ACTIVATED and SWP_FS
Git-commit: bc4ae27d817a4e92071ef67cb6368120cfabe7ec
Patch-mainline: v4.20-rc1
References: fate#322477
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>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
include/linux/swap.h | 11 ++++++-----
mm/page_io.c | 6 +++---
mm/swapfile.c | 11 +++++++----
3 files changed, 16 insertions(+), 12 deletions(-)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -166,12 +166,13 @@ 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_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 */
/* add others here before... */
- SWP_SCANNING = (1 << 11), /* refcount in scan_swap_map */
+ SWP_SCANNING = (1 << 12), /* refcount in scan_swap_map */
};
#define SWAP_CLUSTER_MAX 32UL
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -266,7 +266,7 @@ int __swap_writepage(struct page *page,
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;
@@ -345,7 +345,7 @@ int swap_readpage(struct page *page)
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;
@@ -384,7 +384,7 @@ int swap_set_page_dirty(struct page *pag
{
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);
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1965,12 +1965,13 @@ static void destroy_swap_extents(struct
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;
- mapping->a_ops->swap_deactivate(swap_file);
+ sis->flags &= ~SWP_ACTIVATED;
+ if (mapping->a_ops->swap_deactivate)
+ mapping->a_ops->swap_deactivate(swap_file);
}
}
@@ -2066,8 +2067,10 @@ static int setup_swap_extents(struct swa
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;
}