--- zzzz-none-000/linux-3.10.107/fs/nilfs2/cpfile.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/nilfs2/cpfile.c	2021-02-04 17:41:59.000000000 +0000
@@ -53,6 +53,13 @@
 	return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
 }
 
+static __u64 nilfs_cpfile_first_checkpoint_in_block(const struct inode *cpfile,
+						    unsigned long blkoff)
+{
+	return (__u64)nilfs_cpfile_checkpoints_per_block(cpfile) * blkoff
+		+ 1 - NILFS_MDT(cpfile)->mi_first_entry_offset;
+}
+
 static unsigned long
 nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
 				  __u64 curr,
@@ -146,6 +153,44 @@
 				   create, nilfs_cpfile_block_init, bhp);
 }
 
+/**
+ * nilfs_cpfile_find_checkpoint_block - find and get a buffer on cpfile
+ * @cpfile: inode of cpfile
+ * @start_cno: start checkpoint number (inclusive)
+ * @end_cno: end checkpoint number (inclusive)
+ * @cnop: place to store the next checkpoint number
+ * @bhp: place to store a pointer to buffer_head struct
+ *
+ * Return Value: On success, it returns 0. On error, the following negative
+ * error code is returned.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ *
+ * %-EIO - I/O error
+ *
+ * %-ENOENT - no block exists in the range.
+ */
+static int nilfs_cpfile_find_checkpoint_block(struct inode *cpfile,
+					      __u64 start_cno, __u64 end_cno,
+					      __u64 *cnop,
+					      struct buffer_head **bhp)
+{
+	unsigned long start, end, blkoff;
+	int ret;
+
+	if (unlikely(start_cno > end_cno))
+		return -ENOENT;
+
+	start = nilfs_cpfile_get_blkoff(cpfile, start_cno);
+	end = nilfs_cpfile_get_blkoff(cpfile, end_cno);
+
+	ret = nilfs_mdt_find_block(cpfile, start, end, &blkoff, bhp);
+	if (!ret)
+		*cnop = (blkoff == start) ? start_cno :
+			nilfs_cpfile_first_checkpoint_in_block(cpfile, blkoff);
+	return ret;
+}
+
 static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
 						       __u64 cno)
 {
@@ -403,14 +448,15 @@
 		return -ENOENT; /* checkpoint number 0 is invalid */
 	down_read(&NILFS_MDT(cpfile)->mi_sem);
 
-	for (n = 0; cno < cur_cno && n < nci; cno += ncps) {
-		ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
-		ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
+	for (n = 0; n < nci; cno += ncps) {
+		ret = nilfs_cpfile_find_checkpoint_block(
+			cpfile, cno, cur_cno - 1, &cno, &bh);
 		if (ret < 0) {
-			if (ret != -ENOENT)
-				goto out;
-			continue; /* skip hole */
+			if (likely(ret == -ENOENT))
+				break;
+			goto out;
 		}
+		ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
 
 		kaddr = kmap_atomic(bh->b_page);
 		cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
@@ -942,6 +988,18 @@
 	struct inode *cpfile;
 	int err;
 
+	if (cpsize > sb->s_blocksize) {
+		printk(KERN_ERR
+		       "NILFS: too large checkpoint size: %zu bytes.\n",
+		       cpsize);
+		return -EINVAL;
+	} else if (cpsize < NILFS_MIN_CHECKPOINT_SIZE) {
+		printk(KERN_ERR
+		       "NILFS: too small checkpoint size: %zu bytes.\n",
+		       cpsize);
+		return -EINVAL;
+	}
+
 	cpfile = nilfs_iget_locked(sb, NULL, NILFS_CPFILE_INO);
 	if (unlikely(!cpfile))
 		return -ENOMEM;