[PATCH 26/28] mm, swap: minor clean up for swapon

[Kairui Song <ryncsn@gmail.com>]

From: Kairui Song <kasong@tencent.com>

Setup cluster info first as now it's the most basic info for swap device
now, and clean up swap_map setting. There is no need to pass the
them as argument for multiple functions, they are never set to NULL once
allocated, so just set it once.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 mm/swapfile.c | 62 +++++++++++++++++++++------------------------------
 1 file changed, 26 insertions(+), 36 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 28bb0a74e4a6..c50cbf6578d3 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2440,8 +2440,6 @@ static int swap_node(struct swap_info_struct *si)
 }
 
 static void setup_swap_info(struct swap_info_struct *si, int prio,
-			    unsigned char *swap_map,
-			    struct swap_cluster_info *cluster_info,
 			    unsigned long *zeromap)
 {
 	int i;
@@ -2465,8 +2463,6 @@ static void setup_swap_info(struct swap_info_struct *si, int prio,
 				si->avail_lists[i].prio = -si->prio;
 		}
 	}
-	si->swap_map = swap_map;
-	si->cluster_info = cluster_info;
 	si->zeromap = zeromap;
 }
 
@@ -2493,13 +2489,11 @@ static void _enable_swap_info(struct swap_info_struct *si)
 }
 
 static void enable_swap_info(struct swap_info_struct *si, int prio,
-				unsigned char *swap_map,
-				struct swap_cluster_info *cluster_info,
 				unsigned long *zeromap)
 {
 	spin_lock(&swap_lock);
 	spin_lock(&si->lock);
-	setup_swap_info(si, prio, swap_map, cluster_info, zeromap);
+	setup_swap_info(si, prio, zeromap);
 	spin_unlock(&si->lock);
 	spin_unlock(&swap_lock);
 	/*
@@ -2517,7 +2511,7 @@ static void reinsert_swap_info(struct swap_info_struct *si)
 {
 	spin_lock(&swap_lock);
 	spin_lock(&si->lock);
-	setup_swap_info(si, si->prio, si->swap_map, si->cluster_info, si->zeromap);
+	setup_swap_info(si, si->prio, si->zeromap);
 	_enable_swap_info(si);
 	spin_unlock(&si->lock);
 	spin_unlock(&swap_lock);
@@ -2541,13 +2535,13 @@ static void wait_for_allocation(struct swap_info_struct *si)
 	}
 }
 
-static void free_cluster_info(struct swap_cluster_info *cluster_info,
-			      unsigned long maxpages)
+static void free_swap_cluster_info(struct swap_cluster_info *cluster_info,
+				   unsigned long max)
 {
-	int i, nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
-
+	int i, nr_clusters = DIV_ROUND_UP(max, SWAPFILE_CLUSTER);
 	if (!cluster_info)
 		return;
+	VM_WARN_ON(!nr_clusters);
 	for (i = 0; i < nr_clusters; i++)
 		cluster_table_free(&cluster_info[i]);
 	kvfree(cluster_info);
@@ -2580,7 +2574,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	struct swap_info_struct *p = NULL;
 	unsigned char *swap_map;
 	unsigned long *zeromap;
-	struct swap_cluster_info *cluster_info;
 	struct file *swap_file, *victim;
 	struct address_space *mapping;
 	struct inode *inode;
@@ -2687,14 +2680,13 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 
 	swap_file = p->swap_file;
 	p->swap_file = NULL;
-	p->max = 0;
 	swap_map = p->swap_map;
 	p->swap_map = NULL;
 	zeromap = p->zeromap;
 	p->zeromap = NULL;
-	cluster_info = p->cluster_info;
-	free_cluster_info(cluster_info, p->max);
+	free_swap_cluster_info(p->cluster_info, p->max);
 	p->cluster_info = NULL;
+	p->max = 0;
 	spin_unlock(&p->lock);
 	spin_unlock(&swap_lock);
 	arch_swap_invalidate_area(p->type);
@@ -3067,7 +3059,6 @@ static int setup_swap_map_and_extents(struct swap_info_struct *si,
 
 	if (nr_good_pages) {
 		swap_map[0] = SWAP_MAP_BAD;
-		si->max = maxpages;
 		si->pages = nr_good_pages;
 		nr_extents = setup_swap_extents(si, span);
 		if (nr_extents < 0)
@@ -3089,13 +3080,12 @@ static int setup_swap_map_and_extents(struct swap_info_struct *si,
 #define SWAP_CLUSTER_COLS						\
 	max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
 
-static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
-						union swap_header *swap_header,
-						unsigned long maxpages)
+static int setup_swap_clusters_info(struct swap_info_struct *si,
+				    union swap_header *swap_header,
+				    unsigned long maxpages)
 {
 	unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
 	struct swap_cluster_info *cluster_info;
-	int err = -ENOMEM;
 	unsigned long i;
 
 	cluster_info = kvcalloc(nr_clusters, sizeof(*cluster_info), GFP_KERNEL);
@@ -3151,11 +3141,12 @@ static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
 			list_add_tail(&ci->list, &si->free_clusters);
 		}
 	}
-	return cluster_info;
+	si->cluster_info = cluster_info;
+	return 0;
 err_free:
-	free_cluster_info(cluster_info, maxpages);
+	free_swap_cluster_info(cluster_info, maxpages);
 err:
-	return ERR_PTR(err);
+	return -ENOMEM;
 }
 
 SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
@@ -3173,7 +3164,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	unsigned long maxpages;
 	unsigned char *swap_map = NULL;
 	unsigned long *zeromap = NULL;
-	struct swap_cluster_info *cluster_info = NULL;
 	struct folio *folio = NULL;
 	struct inode *inode = NULL;
 	bool inced_nr_rotate_swap = false;
@@ -3241,13 +3231,19 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	swap_header = kmap_local_folio(folio, 0);
 
 	maxpages = read_swap_header(si, swap_header, inode);
+	si->max = maxpages;
 	if (unlikely(!maxpages)) {
 		error = -EINVAL;
 		goto bad_swap_unlock_inode;
 	}
 
+	error = setup_swap_clusters_info(si, swap_header, maxpages);
+	if (error)
+		goto bad_swap_unlock_inode;
+
 	/* OK, set up the swap map and apply the bad block list */
 	swap_map = vzalloc(maxpages);
+	si->swap_map = swap_map;
 	if (!swap_map) {
 		error = -ENOMEM;
 		goto bad_swap_unlock_inode;
@@ -3288,13 +3284,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		inced_nr_rotate_swap = true;
 	}
 
-	cluster_info = setup_clusters(si, swap_header, maxpages);
-	if (IS_ERR(cluster_info)) {
-		error = PTR_ERR(cluster_info);
-		cluster_info = NULL;
-		goto bad_swap_unlock_inode;
-	}
-
 	if ((swap_flags & SWAP_FLAG_DISCARD) &&
 	    si->bdev && bdev_max_discard_sectors(si->bdev)) {
 		/*
@@ -3345,7 +3334,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	prio = -1;
 	if (swap_flags & SWAP_FLAG_PREFER)
 		prio = swap_flags & SWAP_FLAG_PRIO_MASK;
-	enable_swap_info(si, prio, swap_map, cluster_info, zeromap);
+	enable_swap_info(si, prio, zeromap);
 
 	pr_info("Adding %uk swap on %s.  Priority:%d extents:%d across:%lluk %s%s%s%s\n",
 		K(si->pages), name->name, si->prio, nr_extents,
@@ -3375,10 +3364,11 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	si->swap_file = NULL;
 	si->flags = 0;
 	spin_unlock(&swap_lock);
-	vfree(swap_map);
+	vfree(si->swap_map);
+	si->swap_map = NULL;
+	free_swap_cluster_info(si->cluster_info, si->max);
+	si->cluster_info = NULL;
 	kvfree(zeromap);
-	if (cluster_info)
-		free_cluster_info(cluster_info, maxpages);
 	if (inced_nr_rotate_swap)
 		atomic_dec(&nr_rotate_swap);
 	if (swap_file)
-- 
2.49.0