Merge tag 'mm-nonmm-stable-2024-11-24-02-05' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - The series "resource: A couple of cleanups" from Andy Shevchenko
   performs some cleanups in the resource management code

 - The series "Improve the copy of task comm" from Yafang Shao addresses
   possible race-induced overflows in the management of
   task_struct.comm[]

 - The series "Remove unnecessary header includes from
   {tools/}lib/list_sort.c" from Kuan-Wei Chiu adds some cleanups and a
   small fix to the list_sort library code and to its selftest

 - The series "Enhance min heap API with non-inline functions and
   optimizations" also from Kuan-Wei Chiu optimizes and cleans up the
   min_heap library code

 - The series "nilfs2: Finish folio conversion" from Ryusuke Konishi
   finishes off nilfs2's folioification

 - The series "add detect count for hung tasks" from Lance Yang adds
   more userspace visibility into the hung-task detector's activity

 - Apart from that, singelton patches in many places - please see the
   individual changelogs for details

* tag 'mm-nonmm-stable-2024-11-24-02-05' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (71 commits)
  gdb: lx-symbols: do not error out on monolithic build
  kernel/reboot: replace sprintf() with sysfs_emit()
  lib: util_macros_kunit: add kunit test for util_macros.h
  util_macros.h: fix/rework find_closest() macros
  Improve consistency of '#error' directive messages
  ocfs2: fix uninitialized value in ocfs2_file_read_iter()
  hung_task: add docs for hung_task_detect_count
  hung_task: add detect count for hung tasks
  dma-buf: use atomic64_inc_return() in dma_buf_getfile()
  fs/proc/kcore.c: fix coccinelle reported ERROR instances
  resource: avoid unnecessary resource tree walking in __region_intersects()
  ocfs2: remove unused errmsg function and table
  ocfs2: cluster: fix a typo
  lib/scatterlist: use sg_phys() helper
  checkpatch: always parse orig_commit in fixes tag
  nilfs2: convert metadata aops from writepage to writepages
  nilfs2: convert nilfs_recovery_copy_block() to take a folio
  nilfs2: convert nilfs_page_count_clean_buffers() to take a folio
  nilfs2: remove nilfs_writepage
  nilfs2: convert checkpoint file to be folio-based
  ...

14 files changed, 485 insertions, 441 deletions

diff --git a/fs/nilfs2/alloc.c b/fs/nilfs2/alloc.c
index ba50388ee4bf..ba3e1f591f36 100644
--- a/fs/nilfs2/alloc.c
+++ b/fs/nilfs2/alloc.c
@@ -177,12 +177,14 @@ nilfs_palloc_entry_blkoff(const struct inode *inode, __u64 nr)
  * nilfs_palloc_desc_block_init - initialize buffer of a group descriptor block
  * @inode: inode of metadata file
  * @bh: buffer head of the buffer to be initialized
- * @kaddr: kernel address mapped for the page including the buffer
+ * @from: kernel address mapped for a chunk of the block
+ *
+ * This function does not yet support the case where block size > PAGE_SIZE.
  */
 static void nilfs_palloc_desc_block_init(struct inode *inode,
-					 struct buffer_head *bh, void *kaddr)
+					 struct buffer_head *bh, void *from)
 {
-	struct nilfs_palloc_group_desc *desc = kaddr + bh_offset(bh);
+	struct nilfs_palloc_group_desc *desc = from;
 	unsigned long n = nilfs_palloc_groups_per_desc_block(inode);
 	__le32 nfrees;
 
@@ -337,38 +339,55 @@ static int nilfs_palloc_delete_entry_block(struct inode *inode, __u64 nr)
 }
 
 /**
- * nilfs_palloc_block_get_group_desc - get kernel address of a group descriptor
+ * nilfs_palloc_group_desc_offset - calculate the byte offset of a group
+ *                                  descriptor in the folio containing it
  * @inode: inode of metadata file using this allocator
  * @group: group number
- * @bh: buffer head of the buffer storing the group descriptor block
- * @kaddr: kernel address mapped for the page including the buffer
+ * @bh:    buffer head of the group descriptor block
+ *
+ * Return: Byte offset in the folio of the group descriptor for @group.
  */
-static struct nilfs_palloc_group_desc *
-nilfs_palloc_block_get_group_desc(const struct inode *inode,
-				  unsigned long group,
-				  const struct buffer_head *bh, void *kaddr)
+static size_t nilfs_palloc_group_desc_offset(const struct inode *inode,
+					     unsigned long group,
+					     const struct buffer_head *bh)
 {
-	return (struct nilfs_palloc_group_desc *)(kaddr + bh_offset(bh)) +
-		group % nilfs_palloc_groups_per_desc_block(inode);
+	return offset_in_folio(bh->b_folio, bh->b_data) +
+		sizeof(struct nilfs_palloc_group_desc) *
+		(group % nilfs_palloc_groups_per_desc_block(inode));
+}
+
+/**
+ * nilfs_palloc_bitmap_offset - calculate the byte offset of a bitmap block
+ *                              in the folio containing it
+ * @bh: buffer head of the bitmap block
+ *
+ * Return: Byte offset in the folio of the bitmap block for @bh.
+ */
+static size_t nilfs_palloc_bitmap_offset(const struct buffer_head *bh)
+{
+	return offset_in_folio(bh->b_folio, bh->b_data);
 }
 
 /**
- * nilfs_palloc_block_get_entry - get kernel address of an entry
+ * nilfs_palloc_entry_offset - calculate the byte offset of an entry in the
+ *                             folio containing it
  * @inode: inode of metadata file using this allocator
- * @nr: serial number of the entry (e.g. inode number)
- * @bh: buffer head of the buffer storing the entry block
- * @kaddr: kernel address mapped for the page including the buffer
+ * @nr:    serial number of the entry (e.g. inode number)
+ * @bh:    buffer head of the entry block
+ *
+ * Return: Byte offset in the folio of the entry @nr.
  */
-void *nilfs_palloc_block_get_entry(const struct inode *inode, __u64 nr,
-				   const struct buffer_head *bh, void *kaddr)
+size_t nilfs_palloc_entry_offset(const struct inode *inode, __u64 nr,
+				 const struct buffer_head *bh)
 {
-	unsigned long entry_offset, group_offset;
+	unsigned long entry_index_in_group, entry_index_in_block;
 
-	nilfs_palloc_group(inode, nr, &group_offset);
-	entry_offset = group_offset % NILFS_MDT(inode)->mi_entries_per_block;
+	nilfs_palloc_group(inode, nr, &entry_index_in_group);
+	entry_index_in_block = entry_index_in_group %
+		NILFS_MDT(inode)->mi_entries_per_block;
 
-	return kaddr + bh_offset(bh) +
-		entry_offset * NILFS_MDT(inode)->mi_entry_size;
+	return offset_in_folio(bh->b_folio, bh->b_data) +
+		entry_index_in_block * NILFS_MDT(inode)->mi_entry_size;
 }
 
 /**
@@ -506,7 +525,7 @@ int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
 	struct buffer_head *desc_bh, *bitmap_bh;
 	struct nilfs_palloc_group_desc *desc;
 	unsigned char *bitmap;
-	void *desc_kaddr, *bitmap_kaddr;
+	size_t doff, boff;
 	unsigned long group, maxgroup, ngroups;
 	unsigned long group_offset, maxgroup_offset;
 	unsigned long n, entries_per_group;
@@ -529,17 +548,17 @@ int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
 		ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
 		if (ret < 0)
 			return ret;
-		desc_kaddr = kmap_local_page(desc_bh->b_page);
-		desc = nilfs_palloc_block_get_group_desc(
-			inode, group, desc_bh, desc_kaddr);
+
+		doff = nilfs_palloc_group_desc_offset(inode, group, desc_bh);
+		desc = kmap_local_folio(desc_bh->b_folio, doff);
 		n = nilfs_palloc_rest_groups_in_desc_block(inode, group,
 							   maxgroup);
-		for (j = 0; j < n; j++, desc++, group++, group_offset = 0) {
+		for (j = 0; j < n; j++, group++, group_offset = 0) {
 			lock = nilfs_mdt_bgl_lock(inode, group);
-			if (nilfs_palloc_group_desc_nfrees(desc, lock) == 0)
+			if (nilfs_palloc_group_desc_nfrees(&desc[j], lock) == 0)
 				continue;
 
-			kunmap_local(desc_kaddr);
+			kunmap_local(desc);
 			ret = nilfs_palloc_get_bitmap_block(inode, group, 1,
 							    &bitmap_bh);
 			if (unlikely(ret < 0)) {
@@ -547,12 +566,14 @@ int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
 				return ret;
 			}
 
-			desc_kaddr = kmap_local_page(desc_bh->b_page);
-			desc = nilfs_palloc_block_get_group_desc(
-				inode, group, desc_bh, desc_kaddr);
+			/*
+			 * Re-kmap the folio containing the first (and
+			 * subsequent) group descriptors.
+			 */
+			desc = kmap_local_folio(desc_bh->b_folio, doff);
 
-			bitmap_kaddr = kmap_local_page(bitmap_bh->b_page);
-			bitmap = bitmap_kaddr + bh_offset(bitmap_bh);
+			boff = nilfs_palloc_bitmap_offset(bitmap_bh);
+			bitmap = kmap_local_folio(bitmap_bh->b_folio, boff);
 			pos = nilfs_palloc_find_available_slot(
 				bitmap, group_offset, entries_per_group, lock,
 				wrap);
@@ -562,14 +583,14 @@ int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
 			 * beginning, the wrap flag only has an effect on the
 			 * first search.
 			 */
-			kunmap_local(bitmap_kaddr);
+			kunmap_local(bitmap);
 			if (pos >= 0)
 				goto found;
 
 			brelse(bitmap_bh);
 		}
 
-		kunmap_local(desc_kaddr);
+		kunmap_local(desc);
 		brelse(desc_bh);
 	}
 
@@ -578,9 +599,9 @@ int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
 
 found:
 	/* found a free entry */
-	nilfs_palloc_group_desc_add_entries(desc, lock, -1);
+	nilfs_palloc_group_desc_add_entries(&desc[j], lock, -1);
 	req->pr_entry_nr = entries_per_group * group + pos;
-	kunmap_local(desc_kaddr);
+	kunmap_local(desc);
 
 	req->pr_desc_bh = desc_bh;
 	req->pr_bitmap_bh = bitmap_bh;
@@ -611,18 +632,18 @@ void nilfs_palloc_commit_alloc_entry(struct inode *inode,
 void nilfs_palloc_commit_free_entry(struct inode *inode,
 				    struct nilfs_palloc_req *req)
 {
-	struct nilfs_palloc_group_desc *desc;
 	unsigned long group, group_offset;
+	size_t doff, boff;
+	struct nilfs_palloc_group_desc *desc;
 	unsigned char *bitmap;
-	void *desc_kaddr, *bitmap_kaddr;
 	spinlock_t *lock;
 
 	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
-	desc_kaddr = kmap_local_page(req->pr_desc_bh->b_page);
-	desc = nilfs_palloc_block_get_group_desc(inode, group,
-						 req->pr_desc_bh, desc_kaddr);
-	bitmap_kaddr = kmap_local_page(req->pr_bitmap_bh->b_page);
-	bitmap = bitmap_kaddr + bh_offset(req->pr_bitmap_bh);
+	doff = nilfs_palloc_group_desc_offset(inode, group, req->pr_desc_bh);
+	desc = kmap_local_folio(req->pr_desc_bh->b_folio, doff);
+
+	boff = nilfs_palloc_bitmap_offset(req->pr_bitmap_bh);
+	bitmap = kmap_local_folio(req->pr_bitmap_bh->b_folio, boff);
 	lock = nilfs_mdt_bgl_lock(inode, group);
 
 	if (!nilfs_clear_bit_atomic(lock, group_offset, bitmap))
@@ -633,8 +654,8 @@ void nilfs_palloc_commit_free_entry(struct inode *inode,
 	else
 		nilfs_palloc_group_desc_add_entries(desc, lock, 1);
 
-	kunmap_local(bitmap_kaddr);
-	kunmap_local(desc_kaddr);
+	kunmap_local(bitmap);
+	kunmap_local(desc);
 
 	mark_buffer_dirty(req->pr_desc_bh);
 	mark_buffer_dirty(req->pr_bitmap_bh);
@@ -653,17 +674,17 @@ void nilfs_palloc_abort_alloc_entry(struct inode *inode,
 				    struct nilfs_palloc_req *req)
 {
 	struct nilfs_palloc_group_desc *desc;
-	void *desc_kaddr, *bitmap_kaddr;
+	size_t doff, boff;
 	unsigned char *bitmap;
 	unsigned long group, group_offset;
 	spinlock_t *lock;
 
 	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
-	desc_kaddr = kmap_local_page(req->pr_desc_bh->b_page);
-	desc = nilfs_palloc_block_get_group_desc(inode, group,
-						 req->pr_desc_bh, desc_kaddr);
-	bitmap_kaddr = kmap_local_page(req->pr_bitmap_bh->b_page);
-	bitmap = bitmap_kaddr + bh_offset(req->pr_bitmap_bh);
+	doff = nilfs_palloc_group_desc_offset(inode, group, req->pr_desc_bh);
+	desc = kmap_local_folio(req->pr_desc_bh->b_folio, doff);
+
+	boff = nilfs_palloc_bitmap_offset(req->pr_bitmap_bh);
+	bitmap = kmap_local_folio(req->pr_bitmap_bh->b_folio, boff);
 	lock = nilfs_mdt_bgl_lock(inode, group);
 
 	if (!nilfs_clear_bit_atomic(lock, group_offset, bitmap))
@@ -674,8 +695,8 @@ void nilfs_palloc_abort_alloc_entry(struct inode *inode,
 	else
 		nilfs_palloc_group_desc_add_entries(desc, lock, 1);
 
-	kunmap_local(bitmap_kaddr);
-	kunmap_local(desc_kaddr);
+	kunmap_local(bitmap);
+	kunmap_local(desc);
 
 	brelse(req->pr_bitmap_bh);
 	brelse(req->pr_desc_bh);
@@ -739,7 +760,7 @@ int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)
 	struct buffer_head *desc_bh, *bitmap_bh;
 	struct nilfs_palloc_group_desc *desc;
 	unsigned char *bitmap;
-	void *desc_kaddr, *bitmap_kaddr;
+	size_t doff, boff;
 	unsigned long group, group_offset;
 	__u64 group_min_nr, last_nrs[8];
 	const unsigned long epg = nilfs_palloc_entries_per_group(inode);
@@ -767,8 +788,8 @@ int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)
 		/* Get the first entry number of the group */
 		group_min_nr = (__u64)group * epg;
 
-		bitmap_kaddr = kmap_local_page(bitmap_bh->b_page);
-		bitmap = bitmap_kaddr + bh_offset(bitmap_bh);
+		boff = nilfs_palloc_bitmap_offset(bitmap_bh);
+		bitmap = kmap_local_folio(bitmap_bh->b_folio, boff);
 		lock = nilfs_mdt_bgl_lock(inode, group);
 
 		j = i;
@@ -813,7 +834,7 @@ int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)
 			entry_start = rounddown(group_offset, epb);
 		} while (true);
 
-		kunmap_local(bitmap_kaddr);
+		kunmap_local(bitmap);
 		mark_buffer_dirty(bitmap_bh);
 		brelse(bitmap_bh);
 
@@ -827,11 +848,10 @@ int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)
 					   inode->i_ino);
 		}
 
-		desc_kaddr = kmap_local_page(desc_bh->b_page);
-		desc = nilfs_palloc_block_get_group_desc(
-			inode, group, desc_bh, desc_kaddr);
+		doff = nilfs_palloc_group_desc_offset(inode, group, desc_bh);
+		desc = kmap_local_folio(desc_bh->b_folio, doff);
 		nfree = nilfs_palloc_group_desc_add_entries(desc, lock, n);
-		kunmap_local(desc_kaddr);
+		kunmap_local(desc);
 		mark_buffer_dirty(desc_bh);
 		nilfs_mdt_mark_dirty(inode);
 		brelse(desc_bh);
diff --git a/fs/nilfs2/alloc.h b/fs/nilfs2/alloc.h
index e19d7eb10084..3f115ab7e9a7 100644
--- a/fs/nilfs2/alloc.h
+++ b/fs/nilfs2/alloc.h
@@ -31,8 +31,8 @@ nilfs_palloc_entries_per_group(const struct inode *inode)
 int nilfs_palloc_init_blockgroup(struct inode *, unsigned int);
 int nilfs_palloc_get_entry_block(struct inode *, __u64, int,
 				 struct buffer_head **);
-void *nilfs_palloc_block_get_entry(const struct inode *, __u64,
-				   const struct buffer_head *, void *);
+size_t nilfs_palloc_entry_offset(const struct inode *inode, __u64 nr,
+				 const struct buffer_head *bh);
 
 int nilfs_palloc_count_max_entries(struct inode *, u64, u64 *);
 
diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index f0ce37552446..c20207d7a989 100644
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -68,54 +68,41 @@ static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
 static unsigned int
 nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
 					 struct buffer_head *bh,
-					 void *kaddr,
 					 unsigned int n)
 {
-	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+	struct nilfs_checkpoint *cp;
 	unsigned int count;
 
+	cp = kmap_local_folio(bh->b_folio,
+			      offset_in_folio(bh->b_folio, bh->b_data));
 	count = le32_to_cpu(cp->cp_checkpoints_count) + n;
 	cp->cp_checkpoints_count = cpu_to_le32(count);
+	kunmap_local(cp);
 	return count;
 }
 
 static unsigned int
 nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
 					 struct buffer_head *bh,
-					 void *kaddr,
 					 unsigned int n)
 {
-	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+	struct nilfs_checkpoint *cp;
 	unsigned int count;
 
+	cp = kmap_local_folio(bh->b_folio,
+			      offset_in_folio(bh->b_folio, bh->b_data));
 	WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
 	count = le32_to_cpu(cp->cp_checkpoints_count) - n;
 	cp->cp_checkpoints_count = cpu_to_le32(count);
+	kunmap_local(cp);
 	return count;
 }
 
-static inline struct nilfs_cpfile_header *
-nilfs_cpfile_block_get_header(const struct inode *cpfile,
-			      struct buffer_head *bh,
-			      void *kaddr)
-{
-	return kaddr + bh_offset(bh);
-}
-
-static struct nilfs_checkpoint *
-nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
-				  struct buffer_head *bh,
-				  void *kaddr)
-{
-	return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
-		NILFS_MDT(cpfile)->mi_entry_size;
-}
-
 static void nilfs_cpfile_block_init(struct inode *cpfile,
 				    struct buffer_head *bh,
-				    void *kaddr)
+				    void *from)
 {
-	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+	struct nilfs_checkpoint *cp = from;
 	size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 	int n = nilfs_cpfile_checkpoints_per_block(cpfile);
 
@@ -125,6 +112,54 @@ static void nilfs_cpfile_block_init(struct inode *cpfile,
 	}
 }
 
+/**
+ * nilfs_cpfile_checkpoint_offset - calculate the byte offset of a checkpoint
+ *                                  entry in the folio containing it
+ * @cpfile: checkpoint file inode
+ * @cno:    checkpoint number
+ * @bh:     buffer head of block containing checkpoint indexed by @cno
+ *
+ * Return: Byte offset in the folio of the checkpoint specified by @cno.
+ */
+static size_t nilfs_cpfile_checkpoint_offset(const struct inode *cpfile,
+					     __u64 cno,
+					     struct buffer_head *bh)
+{
+	return offset_in_folio(bh->b_folio, bh->b_data) +
+		nilfs_cpfile_get_offset(cpfile, cno) *
+		NILFS_MDT(cpfile)->mi_entry_size;
+}
+
+/**
+ * nilfs_cpfile_cp_snapshot_list_offset - calculate the byte offset of a
+ *                                        checkpoint snapshot list in the folio
+ *                                        containing it
+ * @cpfile: checkpoint file inode
+ * @cno:    checkpoint number
+ * @bh:     buffer head of block containing checkpoint indexed by @cno
+ *
+ * Return: Byte offset in the folio of the checkpoint snapshot list specified
+ *         by @cno.
+ */
+static size_t nilfs_cpfile_cp_snapshot_list_offset(const struct inode *cpfile,
+						   __u64 cno,
+						   struct buffer_head *bh)
+{
+	return nilfs_cpfile_checkpoint_offset(cpfile, cno, bh) +
+		offsetof(struct nilfs_checkpoint, cp_snapshot_list);
+}
+
+/**
+ * nilfs_cpfile_ch_snapshot_list_offset - calculate the byte offset of the
+ *                                        snapshot list in the header
+ *
+ * Return: Byte offset in the folio of the checkpoint snapshot list
+ */
+static size_t nilfs_cpfile_ch_snapshot_list_offset(void)
+{
+	return offsetof(struct nilfs_cpfile_header, ch_snapshot_list);
+}
+
 static int nilfs_cpfile_get_header_block(struct inode *cpfile,
 					 struct buffer_head **bhp)
 {
@@ -214,7 +249,7 @@ int nilfs_cpfile_read_checkpoint(struct inode *cpfile, __u64 cno,
 {
 	struct buffer_head *cp_bh;
 	struct nilfs_checkpoint *cp;
-	void *kaddr;
+	size_t offset;
 	int ret;
 
 	if (cno < 1 || cno > nilfs_mdt_cno(cpfile))
@@ -228,8 +263,8 @@ int nilfs_cpfile_read_checkpoint(struct inode *cpfile, __u64 cno,
 		goto out_sem;
 	}
 
-	kaddr = kmap_local_page(cp_bh->b_page);
-	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	offset = nilfs_cpfile_checkpoint_offset(cpfile, cno, cp_bh);
+	cp = kmap_local_folio(cp_bh->b_folio, offset);
 	if (nilfs_checkpoint_invalid(cp)) {
 		ret = -EINVAL;
 		goto put_cp;
@@ -254,7 +289,7 @@ int nilfs_cpfile_read_checkpoint(struct inode *cpfile, __u64 cno,
 	root->ifile = ifile;
 
 put_cp:
-	kunmap_local(kaddr);
+	kunmap_local(cp);
 	brelse(cp_bh);
 out_sem:
 	up_read(&NILFS_MDT(cpfile)->mi_sem);
@@ -282,7 +317,7 @@ int nilfs_cpfile_create_checkpoint(struct inode *cpfile, __u64 cno)
 	struct buffer_head *header_bh, *cp_bh;
 	struct nilfs_cpfile_header *header;
 	struct nilfs_checkpoint *cp;
-	void *kaddr;
+	size_t offset;
 	int ret;
 
 	if (WARN_ON_ONCE(cno < 1))
@@ -297,24 +332,22 @@ int nilfs_cpfile_create_checkpoint(struct inode *cpfile, __u64 cno)
 	if (unlikely(ret < 0))
 		goto out_header;
 
-	kaddr = kmap_local_page(cp_bh->b_page);
-	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	offset = nilfs_cpfile_checkpoint_offset(cpfile, cno, cp_bh);
+	cp = kmap_local_folio(cp_bh->b_folio, offset);
 	if (nilfs_checkpoint_invalid(cp)) {
 		/* a newly-created checkpoint */
 		nilfs_checkpoint_clear_invalid(cp);
+		kunmap_local(cp);
 		if (!nilfs_cpfile_is_in_first(cpfile, cno))
 			nilfs_cpfile_block_add_valid_checkpoints(cpfile, cp_bh,
-								 kaddr, 1);
-		kunmap_local(kaddr);
+								 1);
 
-		kaddr = kmap_local_page(header_bh->b_page);
-		header = nilfs_cpfile_block_get_header(cpfile, header_bh,
-						       kaddr);
+		header = kmap_local_folio(header_bh->b_folio, 0);
 		le64_add_cpu(&header->ch_ncheckpoints, 1);
-		kunmap_local(kaddr);
+		kunmap_local(header);
 		mark_buffer_dirty(header_bh);
 	} else {
-		kunmap_local(kaddr);
+		kunmap_local(cp);
 	}
 
 	/* Force the buffer and the inode to become dirty */
@@ -353,7 +386,7 @@ int nilfs_cpfile_finalize_checkpoint(struct inode *cpfile, __u64 cno,
 {
 	struct buffer_head *cp_bh;
 	struct nilfs_checkpoint *cp;
-	void *kaddr;
+	size_t offset;
 	int ret;
 
 	if (WARN_ON_ONCE(cno < 1))
@@ -367,10 +400,10 @@ int nilfs_cpfile_finalize_checkpoint(struct inode *cpfile, __u64 cno,
 		goto out_sem;
 	}
 
-	kaddr = kmap_local_page(cp_bh->b_page);
-	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	offset = nilfs_cpfile_checkpoint_offset(cpfile, cno, cp_bh);
+	cp = kmap_local_folio(cp_bh->b_folio, offset);
 	if (unlikely(nilfs_checkpoint_invalid(cp))) {
-		kunmap_local(kaddr);
+		kunmap_local(cp);
 		brelse(cp_bh);
 		goto error;
 	}
@@ -391,7 +424,7 @@ int nilfs_cpfile_finalize_checkpoint(struct inode *cpfile, __u64 cno,
 	nilfs_write_inode_common(root->ifile, &cp->cp_ifile_inode);
 	nilfs_bmap_write(NILFS_I(root->ifile)->i_bmap, &cp->cp_ifile_inode);
 
-	kunmap_local(kaddr);
+	kunmap_local(cp);
 	brelse(cp_bh);
 out_sem:
 	up_write(&NILFS_MDT(cpfile)->mi_sem);
@@ -432,6 +465,7 @@ int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
 	struct nilfs_checkpoint *cp;
 	size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 	__u64 cno;
+	size_t offset;
 	void *kaddr;
 	unsigned long tnicps;
 	int ret, ncps, nicps, nss, count, i;
@@ -462,9 +496,8 @@ int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
 			continue;
 		}
 
-		kaddr = kmap_local_page(cp_bh->b_page);
-		cp = nilfs_cpfile_block_get_checkpoint(
-			cpfile, cno, cp_bh, kaddr);
+		offset = nilfs_cpfile_checkpoint_offset(cpfile, cno, cp_bh);
+		cp = kaddr = kmap_local_folio(cp_bh->b_folio, offset);
 		nicps = 0;
 		for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
 			if (nilfs_checkpoint_snapshot(cp)) {
@@ -474,43 +507,42 @@ int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
 				nicps++;
 			}
 		}
-		if (nicps > 0) {
-			tnicps += nicps;
-			mark_buffer_dirty(cp_bh);
-			nilfs_mdt_mark_dirty(cpfile);
-			if (!nilfs_cpfile_is_in_first(cpfile, cno)) {
-				count =
-				  nilfs_cpfile_block_sub_valid_checkpoints(
-						cpfile, cp_bh, kaddr, nicps);
-				if (count == 0) {
-					/* make hole */
-					kunmap_local(kaddr);
-					brelse(cp_bh);
-					ret =
-					  nilfs_cpfile_delete_checkpoint_block(
-								   cpfile, cno);
-					if (ret == 0)
-						continue;
-					nilfs_err(cpfile->i_sb,
-						  "error %d deleting checkpoint block",
-						  ret);
-					break;
-				}
-			}
+		kunmap_local(kaddr);
+
+		if (nicps <= 0) {
+			brelse(cp_bh);
+			continue;
 		}
 
-		kunmap_local(kaddr);
+		tnicps += nicps;
+		mark_buffer_dirty(cp_bh);
+		nilfs_mdt_mark_dirty(cpfile);
+		if (nilfs_cpfile_is_in_first(cpfile, cno)) {
+			brelse(cp_bh);
+			continue;
+		}
+
+		count = nilfs_cpfile_block_sub_valid_checkpoints(cpfile, cp_bh,
+								 nicps);
 		brelse(cp_bh);
+		if (count)
+			continue;
+
+		/* Delete the block if there are no more valid checkpoints */
+		ret = nilfs_cpfile_delete_checkpoint_block(cpfile, cno);
+		if (unlikely(ret)) {
+			nilfs_err(cpfile->i_sb,
+				  "error %d deleting checkpoint block", ret);
+			break;
+		}
 	}
 
 	if (tnicps > 0) {
-		kaddr = kmap_local_page(header_bh->b_page);
-		header = nilfs_cpfile_block_get_header(cpfile, header_bh,
-						       kaddr);
+		header = kmap_local_folio(header_bh->b_folio, 0);
 		le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 		mark_buffer_dirty(header_bh);
 		nilfs_mdt_mark_dirty(cpfile);
-		kunmap_local(kaddr);
+		kunmap_local(header);
 	}
 
 	brelse(header_bh);
@@ -544,6 +576,7 @@ static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 	struct buffer_head *bh;
 	size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 	__u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
+	size_t offset;
 	void *kaddr;
 	int n, ret;
 	int ncps, i;
@@ -562,8 +595,8 @@ static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 		}
 		ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
 
-		kaddr = kmap_local_page(bh->b_page);
-		cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
+		offset = nilfs_cpfile_checkpoint_offset(cpfile, cno, bh);
+		cp = kaddr = kmap_local_folio(bh->b_folio, offset);
 		for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
 			if (!nilfs_checkpoint_invalid(cp)) {
 				nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
@@ -597,7 +630,7 @@ static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 	struct nilfs_cpinfo *ci = buf;
 	__u64 curr = *cnop, next;
 	unsigned long curr_blkoff, next_blkoff;
-	void *kaddr;
+	size_t offset;
 	int n = 0, ret;
 
 	down_read(&NILFS_MDT(cpfile)->mi_sem);
@@ -606,10 +639,9 @@ static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 		ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 		if (ret < 0)
 			goto out;
-		kaddr = kmap_local_page(bh->b_page);
-		header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
+		header = kmap_local_folio(bh->b_folio, 0);
 		curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
-		kunmap_local(kaddr);
+		kunmap_local(header);
 		brelse(bh);
 		if (curr == 0) {
 			ret = 0;
@@ -627,9 +659,9 @@ static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 			ret = 0; /* No snapshots (started from a hole block) */
 		goto out;
 	}
-	kaddr = kmap_local_page(bh->b_page);
+	offset = nilfs_cpfile_checkpoint_offset(cpfile, curr, bh);
+	cp = kmap_local_folio(bh->b_folio, offset);
 	while (n < nci) {
-		cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
 		curr = ~(__u64)0; /* Terminator */
 		if (unlikely(nilfs_checkpoint_invalid(cp) ||
 			     !nilfs_checkpoint_snapshot(cp)))
@@ -641,9 +673,9 @@ static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 		if (next == 0)
 			break; /* reach end of the snapshot list */
 
+		kunmap_local(cp);
 		next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
 		if (curr_blkoff != next_blkoff) {
-			kunmap_local(kaddr);
 			brelse(bh);
 			ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
 								0, &bh);
@@ -651,12 +683,13 @@ static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 				WARN_ON(ret == -ENOENT);
 				goto out;
 			}
-			kaddr = kmap_local_page(bh->b_page);
 		}
+		offset = nilfs_cpfile_checkpoint_offset(cpfile, next, bh);
+		cp = kmap_local_folio(bh->b_folio, offset);
 		curr = next;
 		curr_blkoff = next_blkoff;
 	}
-	kunmap_local(kaddr);
+	kunmap_local(cp);
 	brelse(bh);
 	*cnop = curr;
 	ret = n;
@@ -733,26 +766,6 @@ int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
 	return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 }
 
-static struct nilfs_snapshot_list *
-nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
-				     __u64 cno,
-				     struct buffer_head *bh,
-				     void *kaddr)
-{
-	struct nilfs_cpfile_header *header;
-	struct nilfs_checkpoint *cp;
-	struct nilfs_snapshot_list *list;
-
-	if (cno != 0) {
-		cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
-		list = &cp->cp_snapshot_list;
-	} else {
-		header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
-		list = &header->ch_snapshot_list;
-	}
-	return list;
-}
-
 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 {
 	struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
@@ -761,94 +774,103 @@ static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 	struct nilfs_snapshot_list *list;
 	__u64 curr, prev;
 	unsigned long curr_blkoff, prev_blkoff;
-	void *kaddr;
+	size_t offset, curr_list_offset, prev_list_offset;
 	int ret;
 
 	if (cno == 0)
 		return -ENOENT; /* checkpoint number 0 is invalid */
 	down_write(&NILFS_MDT(cpfile)->mi_sem);
 
+	ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+	if (unlikely(ret < 0))
+		goto out_sem;
+
 	ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 	if (ret < 0)
-		goto out_sem;
-	kaddr = kmap_local_page(cp_bh->b_page);
-	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+		goto out_header;
+
+	offset = nilfs_cpfile_checkpoint_offset(cpfile, cno, cp_bh);
+	cp = kmap_local_folio(cp_bh->b_folio, offset);
 	if (nilfs_checkpoint_invalid(cp)) {
 		ret = -ENOENT;
-		kunmap_local(kaddr);
+		kunmap_local(cp);
 		goto out_cp;
 	}
 	if (nilfs_checkpoint_snapshot(cp)) {
 		ret = 0;
-		kunmap_local(kaddr);
+		kunmap_local(cp);
 		goto out_cp;
 	}
-	kunmap_local(kaddr);
+	kunmap_local(cp);
 
-	ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
-	if (ret < 0)
-		goto out_cp;
-	kaddr = kmap_local_page(header_bh->b_page);
-	header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
+	/*
+	 * Find the last snapshot before the checkpoint being changed to
+	 * snapshot mode by going backwards through the snapshot list.
+	 * Set "prev" to its checkpoint number, or 0 if not found.
+	 */
+	header = kmap_local_folio(header_bh->b_folio, 0);
 	list = &header->ch_snapshot_list;
 	curr_bh = header_bh;
 	get_bh(curr_bh);
 	curr = 0;
 	curr_blkoff = 0;
+	curr_list_offset = nilfs_cpfile_ch_snapshot_list_offset();
 	prev = le64_to_cpu(list->ssl_prev);
 	while (prev > cno) {
 		prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
 		curr = prev;
+		kunmap_local(list);
 		if (curr_blkoff != prev_blkoff) {
-			kunmap_local(kaddr);
 			brelse(curr_bh);
 			ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
 								0, &curr_bh);
-			if (ret < 0)
-				goto out_header;
-			kaddr = kmap_local_page(curr_bh->b_page);
+			if (unlikely(ret < 0))
+				goto out_cp;
 		}
+		curr_list_offset = nilfs_cpfile_cp_snapshot_list_offset(
+			cpfile, curr, curr_bh);
+		list = kmap_local_folio(curr_bh->b_folio, curr_list_offset);
 		curr_blkoff = prev_blkoff;
-		cp = nilfs_cpfile_block_get_checkpoint(
-			cpfile, curr, curr_bh, kaddr);
-		list = &cp->cp_snapshot_list;
 		prev = le64_to_cpu(list->ssl_prev);
 	}
-	kunmap_local(kaddr);
+	kunmap_local(list);
 
 	if (prev != 0) {
 		ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 							&prev_bh);
 		if (ret < 0)
 			goto out_curr;
+
+		prev_list_offset = nilfs_cpfile_cp_snapshot_list_offset(
+			cpfile, prev, prev_bh);
 	} else {
 		prev_bh = header_bh;
 		get_bh(prev_bh);
+		prev_list_offset = nilfs_cpfile_ch_snapshot_list_offset();
 	}
 
-	kaddr = kmap_local_page(curr_bh->b_page);
-	list = nilfs_cpfile_block_get_snapshot_list(
-		cpfile, curr, curr_bh, kaddr);
+	/* Update the list entry for the next snapshot */
+	list = kmap_local_folio(curr_bh->b_folio, curr_list_offset);
 	list->ssl_prev = cpu_to_le64(cno);
-	kunmap_local(kaddr);
+	kunmap_local(list);
 
-	kaddr = kmap_local_page(cp_bh->b_page);
-	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	/* Update the checkpoint being changed to a snapshot */
+	offset = nilfs_cpfile_checkpoint_offset(cpfile, cno, cp_bh);
+	cp = kmap_local_folio(cp_bh->b_folio, offset);
 	cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
 	cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
 	nilfs_checkpoint_set_snapshot(cp);
-	kunmap_local(kaddr);
+	kunmap_local(cp);