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From:   Gao Xiang <hsiangkao@redhat.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Matthew Wilcox <willy@infradead.org>,
        Gao Xiang <hsiangkao@redhat.com>
Subject: [PATCH] swap: rename SWP_FS to SWAP_FS_OPS to avoid ambiguity
Date:   Sat, 22 Aug 2020 17:02:08 +0800
Message-Id: <20200822090208.24212-1-hsiangkao@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

SWP_FS is used to make swap_{read,write}page() go
through the filesystem, and it's only used for swap
files over NFS for now. Otherwise it will directly
submit IO to blockdev according to swapfile extents
reported by filesystems in advance.

As Matthew pointed out [1], SWP_FS naming is somewhat
confusing, so let's rename to SWP_FS_OPS.

[1] https://lore.kernel.org/r/20200820113448.GM17456@casper.infradead.org
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
---
A follow-on thread / patch here.

 include/linux/swap.h | 2 +-
 mm/page_io.c         | 6 +++---
 mm/swap_state.c      | 2 +-
 mm/swapfile.c        | 2 +-
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 7eb59bc552a5..51029a5f57be 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -170,7 +170,7 @@ enum {
 	SWP_CONTINUED	= (1 << 5),	/* swap_map has count continuation */
 	SWP_BLKDEV	= (1 << 6),	/* its a block device */
 	SWP_ACTIVATED	= (1 << 7),	/* set after swap_activate success */
-	SWP_FS		= (1 << 8),	/* swap file goes through fs */
+	SWP_FS_OPS	= (1 << 8),	/* swapfile operations go 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 */
diff --git a/mm/page_io.c b/mm/page_io.c
index 9e362567d454..72e0b5a5a41f 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -302,7 +302,7 @@ 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_FS) {
+	if (sis->flags & SWP_FS_OPS) {
 		struct kiocb kiocb;
 		struct file *swap_file = sis->swap_file;
 		struct address_space *mapping = swap_file->f_mapping;
@@ -393,7 +393,7 @@ int swap_readpage(struct page *page, bool synchronous)
 		goto out;
 	}
 
-	if (sis->flags & SWP_FS) {
+	if (sis->flags & SWP_FS_OPS) {
 		struct file *swap_file = sis->swap_file;
 		struct address_space *mapping = swap_file->f_mapping;
 
@@ -455,7 +455,7 @@ int swap_set_page_dirty(struct page *page)
 {
 	struct swap_info_struct *sis = page_swap_info(page);
 
-	if (sis->flags & SWP_FS) {
+	if (sis->flags & SWP_FS_OPS) {
 		struct address_space *mapping = sis->swap_file->f_mapping;
 
 		VM_BUG_ON_PAGE(!PageSwapCache(page), page);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index e82f4f8b1f63..135a5d9fad5d 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -573,7 +573,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
 		goto skip;
 
 	/* Test swap type to make sure the dereference is safe */
-	if (likely(si->flags & (SWP_BLKDEV | SWP_FS))) {
+	if (likely(si->flags & (SWP_BLKDEV | SWP_FS_OPS))) {
 		struct inode *inode = si->swap_file->f_mapping->host;
 		if (inode_read_congested(inode))
 			goto skip;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 2937daf3ca02..75681682bec8 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2426,7 +2426,7 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
 		if (ret >= 0)
 			sis->flags |= SWP_ACTIVATED;
 		if (!ret) {
-			sis->flags |= SWP_FS;
+			sis->flags |= SWP_FS_OPS;
 			ret = add_swap_extent(sis, 0, sis->max, 0);
 			*span = sis->pages;
 		}
-- 
2.18.1