From: Omar Sandoval <osandov@xxxxxx>
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.
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
---
include/linux/swap.h | 13 +++++++------
mm/page_io.c | 6 +++---
mm/swapfile.c | 13 ++++++++-----
3 files changed, 18 insertions(+), 14 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 8e2c11e692ba..0fda0aa743f0 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -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
diff --git a/mm/page_io.c b/mm/page_io.c
index aafd19ec1db4..e8653c368069 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);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index d954b71c4f9c..d3f95833d12e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -989,7 +989,7 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size)
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,
@@ -2310,12 +2310,13 @@ 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;
- mapping->a_ops->swap_deactivate(swap_file);
+ sis->flags &= ~SWP_ACTIVATED;
+ if (mapping->a_ops->swap_deactivate)
+ mapping->a_ops->swap_deactivate(swap_file);
}
}
@@ -2411,8 +2412,10 @@ 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;
}
--
2.19.0
