diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index f9111ffa12ff..61da06fda45c 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -33,8 +33,7 @@ static void __fscrypt_decrypt_bio(struct bio *bio, bool done)
 
 	bio_for_each_segment_all(bv, bio, iter_all) {
 		struct page *page = bv->bv_page;
-		int ret = fscrypt_decrypt_page(page->mapping->host, page,
-				PAGE_SIZE, 0, page->index);
+		int ret = fscrypt_decrypt_pagecache_blocks(page, PAGE_SIZE, 0);
 
 		if (ret)
 			SetPageError(page);
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index f82c45ac285a..45c3d0427fb2 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -283,29 +283,47 @@ int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
 EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
 
 /**
- * fscrypt_decrypt_page() - Decrypts a page in-place
- * @inode:     The corresponding inode for the page to decrypt.
- * @page:      The page to decrypt. Must be locked.
- * @len:       Number of bytes in @page to be decrypted.
- * @offs:      Start of data in @page.
- * @lblk_num:  Logical block number.
+ * fscrypt_decrypt_pagecache_blocks() - Decrypt filesystem blocks in a pagecache page
+ * @page:      The locked pagecache page containing the block(s) to decrypt
+ * @len:       Total size of the block(s) to decrypt.  Must be a nonzero
+ *		multiple of the filesystem's block size.
+ * @offs:      Byte offset within @page of the first block to decrypt.  Must be
+ *		a multiple of the filesystem's block size.
  *
- * Decrypts page in-place using the ctx encryption context.
+ * The specified block(s) are decrypted in-place within the pagecache page,
+ * which must still be locked and not uptodate.  Normally, blocksize ==
+ * PAGE_SIZE and the whole page is decrypted at once.
  *
- * Called from the read completion callback.
+ * This is for use by the filesystem's ->readpages() method.
  *
- * Return: Zero on success, non-zero otherwise.
+ * Return: 0 on success; -errno on failure
  */
-int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
-			unsigned int len, unsigned int offs, u64 lblk_num)
+int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
+				     unsigned int offs)
 {
+	const struct inode *inode = page->mapping->host;
+	const unsigned int blockbits = inode->i_blkbits;
+	const unsigned int blocksize = 1 << blockbits;
+	u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) +
+		       (offs >> blockbits);
+	unsigned int i;
+	int err;
+
 	if (WARN_ON_ONCE(!PageLocked(page)))
 		return -EINVAL;
 
-	return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
-				   len, offs, GFP_NOFS);
+	if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
+		return -EINVAL;
+
+	for (i = offs; i < offs + len; i += blocksize, lblk_num++) {
+		err = fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page,
+					  page, blocksize, i, GFP_NOFS);
+		if (err)
+			return err;
+	}
+	return 0;
 }
-EXPORT_SYMBOL(fscrypt_decrypt_page);
+EXPORT_SYMBOL(fscrypt_decrypt_pagecache_blocks);
 
 /**
  * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c7f77c643008..8bfd8941f5ff 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1232,8 +1232,7 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 	if (unlikely(err))
 		page_zero_new_buffers(page, from, to);
 	else if (decrypt)
-		err = fscrypt_decrypt_page(page->mapping->host, page,
-				PAGE_SIZE, 0, page->index);
+		err = fscrypt_decrypt_pagecache_blocks(page, PAGE_SIZE, 0);
 	return err;
 }
 #endif
@@ -4066,8 +4065,8 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 			/* We expect the key to be set. */
 			BUG_ON(!fscrypt_has_encryption_key(inode));
 			BUG_ON(blocksize != PAGE_SIZE);
-			WARN_ON_ONCE(fscrypt_decrypt_page(page->mapping->host,
-						page, PAGE_SIZE, 0, page->index));
+			WARN_ON_ONCE(fscrypt_decrypt_pagecache_blocks(
+						page, PAGE_SIZE, 0));
 		}
 	}
 	if (ext4_should_journal_data(inode)) {
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 315affc99b05..bd8f207a2fb6 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -112,8 +112,9 @@ extern int fscrypt_encrypt_block_inplace(const struct inode *inode,
 					 struct page *page, unsigned int len,
 					 unsigned int offs, u64 lblk_num,
 					 gfp_t gfp_flags);
-extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
-				unsigned int, u64);
+
+extern int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
+					    unsigned int offs);
 extern int fscrypt_decrypt_block_inplace(const struct inode *inode,
 					 struct page *page, unsigned int len,
 					 unsigned int offs, u64 lblk_num);
@@ -310,10 +311,9 @@ static inline int fscrypt_encrypt_block_inplace(const struct inode *inode,
 	return -EOPNOTSUPP;
 }
 
-static inline int fscrypt_decrypt_page(const struct inode *inode,
-				       struct page *page,
-				       unsigned int len, unsigned int offs,
-				       u64 lblk_num)
+static inline int fscrypt_decrypt_pagecache_blocks(struct page *page,
+						   unsigned int len,
+						   unsigned int offs)
 {
 	return -EOPNOTSUPP;
 }