[PATCH 0/7] ecryptfs: remove the remaining struct page usage

[PATCH 0/7] ecryptfs: remove the remaining struct page usage

[Tal Zussman]

Convert the page cache side of the encryption path to folios, and use
plain kernel memory for the buffers that were only pages because of the
old interfaces: the ciphertext block, the header buffer from
ecryptfs_get_zeroed_pages(), and the scatterlists built by
virt_to_scatterlist(). Also make a shrinking truncate zero the tail of
the last folio in place, as other filesystems do, instead of copying
from the zero page through the write path. After this, fs/ecryptfs has
no struct page usage left.

Ran cleanly with fsx and fsstress on ecryptfs over ext4 in the default,
xattr, and passthrough mount options.

---
Tal Zussman (7):
      ecryptfs: remove struct ecryptfs_page_crypt_context
      ecryptfs: use a folio and a buffer in crypt_extent()
      ecryptfs: use kzalloc() for the header buffer
      ecryptfs: use sg_init_one() instead of virt_to_scatterlist()
      ecryptfs: zero the tail of the last folio in place on truncate
      ecryptfs: rename functions to refer to folios
      ecryptfs: refer to folios in comments and printk strings

 fs/ecryptfs/crypto.c          | 145 ++++++++++++------------------------------
 fs/ecryptfs/ecryptfs_kernel.h |  21 ++----
 fs/ecryptfs/inode.c           |  49 ++++++++++----
 fs/ecryptfs/keystore.c        | 114 ++++++++-------------------------
 fs/ecryptfs/mmap.c            |  60 +++++++++--------
 fs/ecryptfs/read_write.c      |  48 +++++++-------
 6 files changed, 157 insertions(+), 280 deletions(-)
---
base-commit: 5b00bf0f3b7ad05eff79b84e3bacf3f98ac67dc6
change-id: 20261014-ecryptfs-folio-67e80ccec7f3

Best regards,
--  
Tal Zussman <tz2294@columbia.edu>

[PATCH 1/7] ecryptfs: remove struct ecryptfs_page_crypt_context

[Tal Zussman]

This has been unused since commit b6c1d8fcbade ("eCryptfs: remove
unused functions and kmem_cache") in 2007. Remove it.

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/ecryptfs/ecryptfs_kernel.h | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 3baccd4143e8..ff5cef83c79c 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -64,17 +64,6 @@ struct ecryptfs_auth_tok_list {
 struct ecryptfs_crypt_stat;
 struct ecryptfs_mount_crypt_stat;
 
-struct ecryptfs_page_crypt_context {
-	struct page *page;
-#define ECRYPTFS_PREPARE_COMMIT_MODE 0
-#define ECRYPTFS_WRITEPAGE_MODE      1
-	unsigned int mode;
-	union {
-		struct file *lower_file;
-		struct writeback_control *wbc;
-	} param;
-};
-
 #if defined(CONFIG_ENCRYPTED_KEYS) || defined(CONFIG_ENCRYPTED_KEYS_MODULE)
 static inline struct ecryptfs_auth_tok *
 ecryptfs_get_encrypted_key_payload_data(struct key *key)

-- 
2.39.5

[PATCH 2/7] ecryptfs: use a folio and a buffer in crypt_extent()

[Tal Zussman]

crypt_extent() currently takes its source and destination as pages, so
ecryptfs_encrypt_page() and ecryptfs_decrypt_page() have to pass
folio_page() of the folio they are given, and the ciphertext buffer in
ecryptfs_encrypt_page() is allocated as a page to match.

The source is a page cache folio, so pass it as one and set up its
scatterlist with sg_set_folio(). The destination is not: it is a
temporary buffer that is only needed to be able to write to the lower
file. There is no reason for it to be a page or folio. Convert it to a
buffer instead, with NULL meaning the operation is done in place on
the folio, which is what ecryptfs_decrypt_page() does.
ecryptfs_encrypt_page() can then kmalloc() it and write it out without
mapping it. Allocate the buffer with GFP_KERNEL. There was no reason to
use GFP_USER as it had previously been doing.

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/ecryptfs/crypto.c | 47 ++++++++++++++++++++---------------------------
 1 file changed, 20 insertions(+), 27 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index e67119b6029c..9b8b0c5a81cd 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -271,8 +271,9 @@ static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
  * crypt_extent
  * @crypt_stat: crypt_stat containing cryptographic context for the
  *              encryption operation
- * @dst_page: The page to write the result into
- * @src_page: The page to read from
+ * @folio: The folio to read from
+ * @dst: The buffer to write the result into, or NULL to crypt the
+ *       folio in place
  * @page_index: The offset in the file (in units of PAGE_SIZE)
  * @extent_offset: Page extent offset for use in generating IV
  * @op: ENCRYPT or DECRYPT to indicate the desired operation
@@ -282,14 +283,12 @@ static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
  * Return zero on success; non-zero otherwise
  */
 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
-			struct page *dst_page,
-			struct page *src_page,
-			pgoff_t page_index,
+			struct folio *folio, void *dst, pgoff_t page_index,
 			unsigned long extent_offset, int op)
 {
 	loff_t extent_base;
 	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
-	struct scatterlist src_sg, dst_sg;
+	struct scatterlist src_sg, dst_sg, *dst_sgp = &src_sg;
 	size_t extent_size = crypt_stat->extent_size;
 	int rc;
 
@@ -297,14 +296,15 @@ static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 	ecryptfs_derive_iv(extent_iv, crypt_stat, extent_base + extent_offset);
 
 	sg_init_table(&src_sg, 1);
-	sg_init_table(&dst_sg, 1);
-
-	sg_set_page(&src_sg, src_page, extent_size,
-		    extent_offset * extent_size);
-	sg_set_page(&dst_sg, dst_page, extent_size,
-		    extent_offset * extent_size);
+	sg_set_folio(&src_sg, folio, extent_size,
+		     extent_offset * extent_size);
+	if (dst) {
+		sg_init_one(&dst_sg, dst + extent_offset * extent_size,
+			    extent_size);
+		dst_sgp = &dst_sg;
+	}
 
-	rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
+	rc = crypt_scatterlist(crypt_stat, dst_sgp, &src_sg, extent_size,
 			       extent_iv, op);
 	if (rc < 0) {
 		printk(KERN_ERR "%s: Error attempting to crypt page with "
@@ -321,7 +321,7 @@ static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
  * ecryptfs_encrypt_page
  * @folio: Folio mapped from the eCryptfs inode for the file; contains
  *        decrypted content that needs to be encrypted (to a temporary
- *        page; not in place) and written out to the lower file
+ *        buffer; not in place) and written out to the lower file
  *
  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
  * that eCryptfs pages may straddle the lower pages -- for instance,
@@ -338,7 +338,6 @@ int ecryptfs_encrypt_page(struct folio *folio)
 	struct inode *ecryptfs_inode;
 	struct ecryptfs_crypt_stat *crypt_stat;
 	char *enc_extent_virt;
-	struct page *enc_extent_page = NULL;
 	loff_t extent_offset;
 	loff_t lower_offset;
 	int rc = 0;
@@ -347,8 +346,8 @@ int ecryptfs_encrypt_page(struct folio *folio)
 	crypt_stat =
 		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
-	enc_extent_page = alloc_page(GFP_USER);
-	if (!enc_extent_page) {
+	enc_extent_virt = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!enc_extent_virt) {
 		rc = -ENOMEM;
 		ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 				"encrypted extent\n");
@@ -358,9 +357,8 @@ int ecryptfs_encrypt_page(struct folio *folio)
 	for (extent_offset = 0;
 	     extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
 	     extent_offset++) {
-		rc = crypt_extent(crypt_stat, enc_extent_page,
-				folio_page(folio, 0), folio->index,
-				extent_offset, ENCRYPT);
+		rc = crypt_extent(crypt_stat, folio, enc_extent_virt,
+				folio->index, extent_offset, ENCRYPT);
 		if (rc) {
 			printk(KERN_ERR "%s: Error encrypting extent; "
 			       "rc = [%d]\n", __func__, rc);
@@ -369,10 +367,8 @@ int ecryptfs_encrypt_page(struct folio *folio)
 	}
 
 	lower_offset = lower_offset_for_page(crypt_stat, folio);
-	enc_extent_virt = kmap_local_page(enc_extent_page);
 	rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 				  PAGE_SIZE);
-	kunmap_local(enc_extent_virt);
 	if (rc < 0) {
 		ecryptfs_printk(KERN_ERR,
 			"Error attempting to write lower page; rc = [%d]\n",
@@ -381,9 +377,7 @@ int ecryptfs_encrypt_page(struct folio *folio)
 	}
 	rc = 0;
 out:
-	if (enc_extent_page) {
-		__free_page(enc_extent_page);
-	}
+	kfree(enc_extent_virt);
 	return rc;
 }
 
@@ -432,8 +426,7 @@ int ecryptfs_decrypt_page(struct folio *folio)
 	for (extent_offset = 0;
 	     extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
 	     extent_offset++) {
-		struct page *page = folio_page(folio, 0);
-		rc = crypt_extent(crypt_stat, page, page, folio->index,
+		rc = crypt_extent(crypt_stat, folio, NULL, folio->index,
 				extent_offset, DECRYPT);
 		if (rc) {
 			printk(KERN_ERR "%s: Error decrypting extent; "

-- 
2.39.5

[PATCH 3/7] ecryptfs: use kzalloc() for the header buffer

[Tal Zussman]

ecryptfs_write_metadata() is only called when a file is created,
where ecryptfs_set_default_sizes() has set metadata_size to
ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE (8 KiB), or PAGE_SIZE if that is
larger. That is an acceptable size for kmalloc(), and the buffer is
only written out with kernel_write() or as an xattr, so it doesn't
need to be page-aligned. Allocate it with kzalloc() and remove
ecryptfs_get_zeroed_pages().

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/ecryptfs/crypto.c | 19 +++----------------
 1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 9b8b0c5a81cd..6a014872e919 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -998,17 +998,6 @@ ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
 	return rc;
 }
 
-static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
-					       unsigned int order)
-{
-	struct page *page;
-
-	page = alloc_pages(gfp_mask | __GFP_ZERO, order);
-	if (page)
-		return (unsigned long) page_address(page);
-	return 0;
-}
-
 /**
  * ecryptfs_write_metadata
  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
@@ -1027,7 +1016,6 @@ int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
 {
 	struct ecryptfs_crypt_stat *crypt_stat =
 		&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
-	unsigned int order;
 	char *virt;
 	size_t virt_len;
 	size_t size = 0;
@@ -1046,15 +1034,14 @@ int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
 		goto out;
 	}
 	virt_len = crypt_stat->metadata_size;
-	order = get_order(virt_len);
 	/* Released in this function */
-	virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
+	virt = kzalloc(virt_len, GFP_KERNEL);
 	if (!virt) {
 		printk(KERN_ERR "%s: Out of memory\n", __func__);
 		rc = -ENOMEM;
 		goto out;
 	}
-	/* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
+	/* Zeroed buffer ensures the in-header unencrypted i_size is set to 0 */
 	rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
 					 ecryptfs_dentry);
 	if (unlikely(rc)) {
@@ -1074,7 +1061,7 @@ int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
 		goto out_free;
 	}
 out_free:
-	free_pages((unsigned long)virt, order);
+	kfree(virt);
 out:
 	return rc;
 }

-- 
2.39.5

[PATCH 4/7] ecryptfs: use sg_init_one() instead of virt_to_scatterlist()

[Tal Zussman]

Every caller passes a kmalloc()-ed buffer or an array inside a kmalloc()-ed
structure, which is physically contiguous and so fits in one
scatterlist entry. Use sg_init_one(), which can't fail, drop the
two-entry arrays and their length checks, and remove
virt_to_scatterlist() and the unused ECRYPTFS_MAX_SCATTERLIST_LEN.

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/ecryptfs/crypto.c          |  46 -----------------
 fs/ecryptfs/ecryptfs_kernel.h |   2 -
 fs/ecryptfs/keystore.c        | 114 +++++++++---------------------------------
 3 files changed, 25 insertions(+), 137 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 6a014872e919..f0e67b48917f 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -149,50 +149,6 @@ void ecryptfs_destroy_mount_crypt_stat(
 	memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 }
 
-/**
- * virt_to_scatterlist
- * @addr: Virtual address
- * @size: Size of data; should be an even multiple of the block size
- * @sg: Pointer to scatterlist array; set to NULL to obtain only
- *      the number of scatterlist structs required in array
- * @sg_size: Max array size
- *
- * Fills in a scatterlist array with page references for a passed
- * virtual address.
- *
- * Returns the number of scatterlist structs in array used
- */
-int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
-			int sg_size)
-{
-	int i = 0;
-	struct page *pg;
-	int offset;
-	int remainder_of_page;
-
-	sg_init_table(sg, sg_size);
-
-	while (size > 0 && i < sg_size) {
-		pg = virt_to_page(addr);
-		offset = offset_in_page(addr);
-		sg_set_page(&sg[i], pg, 0, offset);
-		remainder_of_page = PAGE_SIZE - offset;
-		if (size >= remainder_of_page) {
-			sg[i].length = remainder_of_page;
-			addr += remainder_of_page;
-			size -= remainder_of_page;
-		} else {
-			sg[i].length = size;
-			addr += size;
-			size = 0;
-		}
-		i++;
-	}
-	if (size > 0)
-		return -ENOMEM;
-	return i;
-}
-
 /**
  * crypt_scatterlist
  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
@@ -438,8 +394,6 @@ int ecryptfs_decrypt_page(struct folio *folio)
 	return rc;
 }
 
-#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
-
 /**
  * ecryptfs_init_crypt_ctx
  * @crypt_stat: Uninitialized crypt stats structure
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index ff5cef83c79c..6a74a2bfc833 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -541,8 +541,6 @@ int ecryptfs_encrypt_and_encode_filename(
 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 	const char *name, size_t name_size);
 void ecryptfs_dump_hex(char *data, int bytes);
-int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
-			int sg_size);
 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat);
 void ecryptfs_rotate_iv(unsigned char *iv);
 void ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat);
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index 51651314b7a6..051f7948cf52 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -595,8 +595,8 @@ struct ecryptfs_write_tag_70_packet_silly_stack {
 	struct mutex *tfm_mutex;
 	char *block_aligned_filename;
 	struct ecryptfs_auth_tok *auth_tok;
-	struct scatterlist src_sg[2];
-	struct scatterlist dst_sg[2];
+	struct scatterlist src_sg;
+	struct scatterlist dst_sg;
 	struct crypto_skcipher *skcipher_tfm;
 	struct skcipher_request *skcipher_req;
 	char iv[ECRYPTFS_MAX_IV_BYTES];
@@ -751,24 +751,9 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 	}
 	memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
 	       filename_size);
-	rc = virt_to_scatterlist(s->block_aligned_filename,
-				 s->block_aligned_filename_size, s->src_sg, 2);
-	if (rc < 1) {
-		printk(KERN_ERR "%s: Internal error whilst attempting to "
-		       "convert filename memory to scatterlist; rc = [%d]. "
-		       "block_aligned_filename_size = [%zd]\n", __func__, rc,
-		       s->block_aligned_filename_size);
-		goto out_free_unlock;
-	}
-	rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
-				 s->dst_sg, 2);
-	if (rc < 1) {
-		printk(KERN_ERR "%s: Internal error whilst attempting to "
-		       "convert encrypted filename memory to scatterlist; "
-		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
-		       __func__, rc, s->block_aligned_filename_size);
-		goto out_free_unlock;
-	}
+	sg_init_one(&s->src_sg, s->block_aligned_filename,
+		    s->block_aligned_filename_size);
+	sg_init_one(&s->dst_sg, &dest[s->i], s->block_aligned_filename_size);
 	/* The characters in the first block effectively do the job
 	 * of the IV here, so we just use 0's for the IV. Note the
 	 * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
@@ -787,7 +772,7 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
 		goto out_free_unlock;
 	}
-	skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
+	skcipher_request_set_crypt(s->skcipher_req, &s->src_sg, &s->dst_sg,
 				   s->block_aligned_filename_size, s->iv);
 	rc = crypto_skcipher_encrypt(s->skcipher_req);
 	if (rc) {
@@ -823,8 +808,8 @@ struct ecryptfs_parse_tag_70_packet_silly_stack {
 	struct mutex *tfm_mutex;
 	char *decrypted_filename;
 	struct ecryptfs_auth_tok *auth_tok;
-	struct scatterlist src_sg[2];
-	struct scatterlist dst_sg[2];
+	struct scatterlist src_sg;
+	struct scatterlist dst_sg;
 	struct crypto_skcipher *skcipher_tfm;
 	struct skcipher_request *skcipher_req;
 	char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
@@ -943,15 +928,8 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 		goto out;
 	}
 	mutex_lock(s->tfm_mutex);
-	rc = virt_to_scatterlist(&data[(*packet_size)],
-				 s->block_aligned_filename_size, s->src_sg, 2);
-	if (rc < 1) {
-		printk(KERN_ERR "%s: Internal error whilst attempting to "
-		       "convert encrypted filename memory to scatterlist; "
-		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
-		       __func__, rc, s->block_aligned_filename_size);
-		goto out_unlock;
-	}
+	sg_init_one(&s->src_sg, &data[(*packet_size)],
+		    s->block_aligned_filename_size);
 	(*packet_size) += s->block_aligned_filename_size;
 	s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
 					GFP_KERNEL);
@@ -959,15 +937,8 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 		rc = -ENOMEM;
 		goto out_unlock;
 	}
-	rc = virt_to_scatterlist(s->decrypted_filename,
-				 s->block_aligned_filename_size, s->dst_sg, 2);
-	if (rc < 1) {
-		printk(KERN_ERR "%s: Internal error whilst attempting to "
-		       "convert decrypted filename memory to scatterlist; "
-		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
-		       __func__, rc, s->block_aligned_filename_size);
-		goto out_free_unlock;
-	}
+	sg_init_one(&s->dst_sg, s->decrypted_filename,
+		    s->block_aligned_filename_size);
 
 	s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
 	if (!s->skcipher_req) {
@@ -1007,7 +978,7 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
 		goto out_free_unlock;
 	}
-	skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
+	skcipher_request_set_crypt(s->skcipher_req, &s->src_sg, &s->dst_sg,
 				   s->block_aligned_filename_size, s->iv);
 	rc = crypto_skcipher_decrypt(s->skcipher_req);
 	if (rc) {
@@ -1625,8 +1596,8 @@ static int
 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
 					 struct ecryptfs_crypt_stat *crypt_stat)
 {
-	struct scatterlist dst_sg[2];
-	struct scatterlist src_sg[2];
+	struct scatterlist dst_sg;
+	struct scatterlist src_sg;
 	struct mutex *tfm_mutex;
 	struct crypto_skcipher *tfm;
 	struct skcipher_request *req = NULL;
@@ -1648,28 +1619,12 @@ decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
 		       crypt_stat->cipher, rc);
 		goto out;
 	}
-	rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
-				 auth_tok->session_key.encrypted_key_size,
-				 src_sg, 2);
-	if (rc < 1 || rc > 2) {
-		printk(KERN_ERR "Internal error whilst attempting to convert "
-			"auth_tok->session_key.encrypted_key to scatterlist; "
-			"expected rc = 1; got rc = [%d]. "
-		       "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
-			auth_tok->session_key.encrypted_key_size);
-		goto out;
-	}
+	sg_init_one(&src_sg, auth_tok->session_key.encrypted_key,
+		    auth_tok->session_key.encrypted_key_size);
 	auth_tok->session_key.decrypted_key_size =
 		auth_tok->session_key.encrypted_key_size;
-	rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
-				 auth_tok->session_key.decrypted_key_size,
-				 dst_sg, 2);
-	if (rc < 1 || rc > 2) {
-		printk(KERN_ERR "Internal error whilst attempting to convert "
-			"auth_tok->session_key.decrypted_key to scatterlist; "
-			"expected rc = 1; got rc = [%d]\n", rc);
-		goto out;
-	}
+	sg_init_one(&dst_sg, auth_tok->session_key.decrypted_key,
+		    auth_tok->session_key.decrypted_key_size);
 	mutex_lock(tfm_mutex);
 	req = skcipher_request_alloc(tfm, GFP_KERNEL);
 	if (!req) {
@@ -1692,7 +1647,7 @@ decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
 		rc = -EINVAL;
 		goto out;
 	}
-	skcipher_request_set_crypt(req, src_sg, dst_sg,
+	skcipher_request_set_crypt(req, &src_sg, &dst_sg,
 				   auth_tok->session_key.encrypted_key_size,
 				   NULL);
 	rc = crypto_skcipher_decrypt(req);
@@ -2166,8 +2121,8 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
 	size_t i;
 	size_t encrypted_session_key_valid = 0;
 	char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
-	struct scatterlist dst_sg[2];
-	struct scatterlist src_sg[2];
+	struct scatterlist dst_sg;
+	struct scatterlist src_sg;
 	struct mutex *tfm_mutex = NULL;
 	u8 cipher_code;
 	size_t packet_size_length;
@@ -2242,27 +2197,8 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
 		ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
 		ecryptfs_dump_hex(session_key_encryption_key, 16);
 	}
-	rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
-				 src_sg, 2);
-	if (rc < 1 || rc > 2) {
-		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
-				"for crypt_stat session key; expected rc = 1; "
-				"got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
-				rc, key_rec->enc_key_size);
-		rc = -ENOMEM;
-		goto out;
-	}
-	rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
-				 dst_sg, 2);
-	if (rc < 1 || rc > 2) {
-		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
-				"for crypt_stat encrypted session key; "
-				"expected rc = 1; got rc = [%d]. "
-				"key_rec->enc_key_size = [%zd]\n", rc,
-				key_rec->enc_key_size);
-		rc = -ENOMEM;
-		goto out;
-	}
+	sg_init_one(&src_sg, crypt_stat->key, key_rec->enc_key_size);
+	sg_init_one(&dst_sg, key_rec->enc_key, key_rec->enc_key_size);
 	mutex_lock(tfm_mutex);
 	rc = crypto_skcipher_setkey(tfm, session_key_encryption_key,
 				    crypt_stat->key_size);
@@ -2289,7 +2225,7 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
 	rc = 0;
 	ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
 			crypt_stat->key_size);
-	skcipher_request_set_crypt(req, src_sg, dst_sg,
+	skcipher_request_set_crypt(req, &src_sg, &dst_sg,
 				   (*key_rec).enc_key_size, NULL);
 	rc = crypto_skcipher_encrypt(req);
 	mutex_unlock(tfm_mutex);

-- 
2.39.5

[PATCH 5/7] ecryptfs: zero the tail of the last folio in place on truncate

[Tal Zussman]

A shrinking truncate zeroes the rest of the folio that holds the new
end of the file by copying from the zero page through ecryptfs_write().
Zero the folio in place with folio_zero_range() instead, the way the
truncate helpers in other filesystems do, and encrypt it to the lower
file. This no longer bumps i_size to the end of the folio and writes
that to the metadata before the real size is written. It also removes
the last struct page usage in ecryptfs.

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/ecryptfs/inode.c | 49 ++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 36 insertions(+), 13 deletions(-)

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 525297c7ebd8..c743b0f2ab4b 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -718,6 +718,34 @@ upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
 	return lower_size;
 }
 
+/**
+ * ecryptfs_zero_tail
+ * @inode: The ecryptfs inode
+ * @pos: The file offset from which to zero
+ *
+ * Zero the folio that holds @pos from @pos to its end, and write the
+ * result out to the lower file.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_zero_tail(struct inode *inode, loff_t pos)
+{
+	struct folio *folio;
+	size_t from;
+	int rc;
+
+	folio = read_mapping_folio(inode->i_mapping, pos >> PAGE_SHIFT, NULL);
+	if (IS_ERR(folio))
+		return PTR_ERR(folio);
+	from = offset_in_folio(folio, pos);
+	folio_lock(folio);
+	folio_zero_range(folio, from, folio_size(folio) - from);
+	folio_unlock(folio);
+	rc = ecryptfs_encrypt_page(folio);
+	folio_put(folio);
+	return rc;
+}
+
 /**
  * __ecryptfs_truncate
  * @dentry: The ecryptfs layer dentry
@@ -739,7 +767,6 @@ static int __ecryptfs_truncate(struct dentry *dentry, const struct iattr *ia)
 	loff_t lower_size_before_truncate;
 	loff_t lower_size_after_truncate;
 	struct iattr lower_ia;
-	size_t num_zeros;
 	int rc;
 
 	ecryptfs_iattr_to_lower(&lower_ia, ia);
@@ -788,19 +815,15 @@ static int __ecryptfs_truncate(struct dentry *dentry, const struct iattr *ia)
 	}
 
 	/*
-	 * We're chopping off all the pages down to the page in which
-	 * ia->ia_size is located. Fill in the end of that page from
-	 * (ia->ia_size & ~PAGE_MASK) to PAGE_SIZE with zeros.
+	 * We're chopping off all the folios down to the folio in which
+	 * ia->ia_size is located. Fill in the end of that folio from
+	 * ia->ia_size with zeros.
 	 */
-	num_zeros = PAGE_SIZE - (ia->ia_size & ~PAGE_MASK);
-	if (num_zeros) {
-		rc = ecryptfs_write(inode, page_address(ZERO_PAGE(0)),
-				ia->ia_size, num_zeros);
-		if (rc) {
-			pr_err("Error attempting to zero out the remainder of the end page on reducing truncate; rc = [%d]\n",
-				rc);
-			goto out;
-		}
+	rc = ecryptfs_zero_tail(inode, ia->ia_size);
+	if (rc) {
+		pr_err("Error attempting to zero out the remainder of the end folio on reducing truncate; rc = [%d]\n",
+			rc);
+		goto out;
 	}
 	truncate_setsize(inode, ia->ia_size);
 	rc = ecryptfs_write_inode_size_to_metadata(inode);

-- 
2.39.5

[PATCH 6/7] ecryptfs: rename functions to refer to folios

[Tal Zussman]

ecryptfs_encrypt_page(), ecryptfs_decrypt_page(),
ecryptfs_read_lower_page_segment(), ecryptfs_write_lower_page_segment(),
lower_offset_for_page() and fill_zeros_to_end_of_page() all take a folio
now. Rename them accordingly.

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/ecryptfs/crypto.c          | 16 ++++++++--------
 fs/ecryptfs/ecryptfs_kernel.h |  8 ++++----
 fs/ecryptfs/inode.c           |  2 +-
 fs/ecryptfs/mmap.c            | 26 +++++++++++++-------------
 fs/ecryptfs/read_write.c      | 12 ++++++------
 5 files changed, 32 insertions(+), 32 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index f0e67b48917f..bbaeb9a38db0 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -212,11 +212,11 @@ static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 }
 
 /*
- * lower_offset_for_page
+ * lower_offset_for_folio
  *
  * Convert an eCryptfs page index into a lower byte offset
  */
-static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
+static loff_t lower_offset_for_folio(struct ecryptfs_crypt_stat *crypt_stat,
 				    struct folio *folio)
 {
 	return ecryptfs_lower_header_size(crypt_stat) +
@@ -274,7 +274,7 @@ static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 }
 
 /**
- * ecryptfs_encrypt_page
+ * ecryptfs_encrypt_folio
  * @folio: Folio mapped from the eCryptfs inode for the file; contains
  *        decrypted content that needs to be encrypted (to a temporary
  *        buffer; not in place) and written out to the lower file
@@ -289,7 +289,7 @@ static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
  *
  * Returns zero on success; negative on error
  */
-int ecryptfs_encrypt_page(struct folio *folio)
+int ecryptfs_encrypt_folio(struct folio *folio)
 {
 	struct inode *ecryptfs_inode;
 	struct ecryptfs_crypt_stat *crypt_stat;
@@ -322,7 +322,7 @@ int ecryptfs_encrypt_page(struct folio *folio)
 		}
 	}
 
-	lower_offset = lower_offset_for_page(crypt_stat, folio);
+	lower_offset = lower_offset_for_folio(crypt_stat, folio);
 	rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 				  PAGE_SIZE);
 	if (rc < 0) {
@@ -338,7 +338,7 @@ int ecryptfs_encrypt_page(struct folio *folio)
 }
 
 /**
- * ecryptfs_decrypt_page
+ * ecryptfs_decrypt_folio
  * @folio: Folio mapped from the eCryptfs inode for the file; data read
  *        and decrypted from the lower file will be written into this
  *        page
@@ -353,7 +353,7 @@ int ecryptfs_encrypt_page(struct folio *folio)
  *
  * Returns zero on success; negative on error
  */
-int ecryptfs_decrypt_page(struct folio *folio)
+int ecryptfs_decrypt_folio(struct folio *folio)
 {
 	struct inode *ecryptfs_inode;
 	struct ecryptfs_crypt_stat *crypt_stat;
@@ -367,7 +367,7 @@ int ecryptfs_decrypt_page(struct folio *folio)
 		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 
-	lower_offset = lower_offset_for_page(crypt_stat, folio);
+	lower_offset = lower_offset_for_folio(crypt_stat, folio);
 	page_virt = kmap_local_folio(folio, 0);
 	rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
 				 ecryptfs_inode);
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 6a74a2bfc833..5c7cfb956455 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -549,8 +549,8 @@ void ecryptfs_destroy_mount_crypt_stat(
 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat);
 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat);
 int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode);
-int ecryptfs_encrypt_page(struct folio *folio);
-int ecryptfs_decrypt_page(struct folio *folio);
+int ecryptfs_encrypt_folio(struct folio *folio);
+int ecryptfs_decrypt_folio(struct folio *folio);
 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
 			    struct inode *ecryptfs_inode);
 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry);
@@ -633,13 +633,13 @@ int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
 				      char *sig);
 int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
 			 loff_t offset, size_t size);
-int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
+int ecryptfs_write_lower_folio_segment(struct inode *ecryptfs_inode,
 				      struct folio *folio_for_lower,
 				      size_t offset_in_page, size_t size);
 int ecryptfs_write(struct inode *inode, char *data, loff_t offset, size_t size);
 int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
 			struct inode *ecryptfs_inode);
-int ecryptfs_read_lower_page_segment(struct folio *folio_for_ecryptfs,
+int ecryptfs_read_lower_folio_segment(struct folio *folio_for_ecryptfs,
 				     pgoff_t page_index,
 				     size_t offset_in_page, size_t size,
 				     struct inode *ecryptfs_inode);
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index c743b0f2ab4b..ffd6da87c8ca 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -741,7 +741,7 @@ static int ecryptfs_zero_tail(struct inode *inode, loff_t pos)
 	folio_lock(folio);
 	folio_zero_range(folio, from, folio_size(folio) - from);
 	folio_unlock(folio);
-	rc = ecryptfs_encrypt_page(folio);
+	rc = ecryptfs_encrypt_folio(folio);
 	folio_put(folio);
 	return rc;
 }
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index 07a6c8448100..d841610644ed 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -34,7 +34,7 @@ static int ecryptfs_writepages(struct address_space *mapping,
 	int error;
 
 	while ((folio = writeback_iter(mapping, wbc, folio, &error))) {
-		error = ecryptfs_encrypt_page(folio);
+		error = ecryptfs_encrypt_folio(folio);
 		if (error) {
 			ecryptfs_printk(KERN_WARNING,
 				"Error encrypting folio (index [0x%.16lx])\n",
@@ -133,7 +133,7 @@ ecryptfs_copy_up_encrypted_with_header(struct folio *folio,
 				((view_extent_num * crypt_stat->extent_size)
 				 - crypt_stat->metadata_size);
 
-			rc = ecryptfs_read_lower_page_segment(
+			rc = ecryptfs_read_lower_folio_segment(
 				folio, (lower_offset >> PAGE_SHIFT),
 				(lower_offset & ~PAGE_MASK),
 				crypt_stat->extent_size, folio->mapping->host);
@@ -168,7 +168,7 @@ static int ecryptfs_read_folio(struct file *file, struct folio *folio)
 	int err = 0;
 
 	if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
-		err = ecryptfs_read_lower_page_segment(folio, folio->index, 0,
+		err = ecryptfs_read_lower_folio_segment(folio, folio->index, 0,
 				folio_size(folio), inode);
 	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
 		if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
@@ -184,7 +184,7 @@ static int ecryptfs_read_folio(struct file *file, struct folio *folio)
 			}
 
 		} else {
-			err = ecryptfs_read_lower_page_segment(folio,
+			err = ecryptfs_read_lower_folio_segment(folio,
 					folio->index, 0, folio_size(folio),
 					inode);
 			if (err) {
@@ -194,7 +194,7 @@ static int ecryptfs_read_folio(struct file *file, struct folio *folio)
 			}
 		}
 	} else {
-		err = ecryptfs_decrypt_page(folio);
+		err = ecryptfs_decrypt_folio(folio);
 		if (err) {
 			ecryptfs_printk(KERN_ERR, "Error decrypting page; "
 					"err = [%d]\n", err);
@@ -211,7 +211,7 @@ static int ecryptfs_read_folio(struct file *file, struct folio *folio)
 /*
  * Called with lower inode mutex held.
  */
-static int fill_zeros_to_end_of_page(struct folio *folio, unsigned int to)
+static int fill_zeros_to_end_of_folio(struct folio *folio, unsigned int to)
 {
 	struct inode *inode = folio->mapping->host;
 	int end_byte_in_page;
@@ -261,7 +261,7 @@ static int ecryptfs_write_begin(const struct kiocb *iocb,
 			&ecryptfs_inode_to_private(mapping->host)->crypt_stat;
 
 		if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
-			rc = ecryptfs_read_lower_page_segment(
+			rc = ecryptfs_read_lower_folio_segment(
 				folio, index, 0, PAGE_SIZE, mapping->host);
 			if (rc) {
 				printk(KERN_ERR "%s: Error attempting to read "
@@ -287,7 +287,7 @@ static int ecryptfs_write_begin(const struct kiocb *iocb,
 				}
 				folio_mark_uptodate(folio);
 			} else {
-				rc = ecryptfs_read_lower_page_segment(
+				rc = ecryptfs_read_lower_folio_segment(
 					folio, index, 0, PAGE_SIZE,
 					mapping->host);
 				if (rc) {
@@ -305,7 +305,7 @@ static int ecryptfs_write_begin(const struct kiocb *iocb,
 				folio_zero_range(folio, 0, PAGE_SIZE);
 				folio_mark_uptodate(folio);
 			} else if (len < PAGE_SIZE) {
-				rc = ecryptfs_decrypt_page(folio);
+				rc = ecryptfs_decrypt_folio(folio);
 				if (rc) {
 					printk(KERN_ERR "%s: Error decrypting "
 					       "page at index [%ld]; "
@@ -443,10 +443,10 @@ static int ecryptfs_write_end(const struct kiocb *iocb,
 		&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 	int rc;
 
-	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
+	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_folio"
 			"(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
 	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
-		rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
+		rc = ecryptfs_write_lower_folio_segment(ecryptfs_inode,
 				folio, 0, to);
 		if (!rc) {
 			rc = copied;
@@ -463,13 +463,13 @@ static int ecryptfs_write_end(const struct kiocb *iocb,
 		folio_mark_uptodate(folio);
 	}
 	/* Fills in zeros if 'to' goes beyond inode size */
-	rc = fill_zeros_to_end_of_page(folio, to);
+	rc = fill_zeros_to_end_of_folio(folio, to);
 	if (rc) {
 		ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
 			"zeros in page with index = [0x%.16lx]\n", index);
 		goto out;
 	}
-	rc = ecryptfs_encrypt_page(folio);
+	rc = ecryptfs_encrypt_folio(folio);
 	if (rc) {
 		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
 				"index [0x%.16lx])\n", index);
diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
index b3b451c2b941..611f74061441 100644
--- a/fs/ecryptfs/read_write.c
+++ b/fs/ecryptfs/read_write.c
@@ -39,7 +39,7 @@ int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
 }
 
 /**
- * ecryptfs_write_lower_page_segment
+ * ecryptfs_write_lower_folio_segment
  * @ecryptfs_inode: The eCryptfs inode
  * @folio_for_lower: The folio containing the data to be written to the
  *                  lower file
@@ -54,7 +54,7 @@ int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
  *
  * Returns zero on success; non-zero otherwise
  */
-int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
+int ecryptfs_write_lower_folio_segment(struct inode *ecryptfs_inode,
 				      struct folio *folio_for_lower,
 				      size_t offset_in_page, size_t size)
 {
@@ -168,9 +168,9 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
 		folio_mark_uptodate(ecryptfs_folio);
 		folio_unlock(ecryptfs_folio);
 		if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
-			rc = ecryptfs_encrypt_page(ecryptfs_folio);
+			rc = ecryptfs_encrypt_folio(ecryptfs_folio);
 		else
-			rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
+			rc = ecryptfs_write_lower_folio_segment(ecryptfs_inode,
 						ecryptfs_folio,
 						start_offset_in_page,
 						data_offset);
@@ -227,7 +227,7 @@ int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
 }
 
 /**
- * ecryptfs_read_lower_page_segment
+ * ecryptfs_read_lower_folio_segment
  * @folio_for_ecryptfs: The folio into which data for eCryptfs will be
  *                     written
  * @page_index: Page index in @page_for_ecryptfs from which to start
@@ -243,7 +243,7 @@ int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
  *
  * Returns zero on success; non-zero otherwise
  */
-int ecryptfs_read_lower_page_segment(struct folio *folio_for_ecryptfs,
+int ecryptfs_read_lower_folio_segment(struct folio *folio_for_ecryptfs,
 				     pgoff_t page_index,
 				     size_t offset_in_page, size_t size,
 				     struct inode *ecryptfs_inode)

-- 
2.39.5

[PATCH 7/7] ecryptfs: refer to folios in comments and printk strings

[Tal Zussman]

Update the comments and printk strings to refer to folios instead of
pages. While at it, join the strings that were split across lines, use
pr_err() for the printk(KERN_ERR) calls among them, and fix the block
comment style.

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/ecryptfs/crypto.c     | 17 ++++++++---------
 fs/ecryptfs/mmap.c       | 36 +++++++++++++++++-------------------
 fs/ecryptfs/read_write.c | 36 ++++++++++++++++++------------------
 3 files changed, 43 insertions(+), 46 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index bbaeb9a38db0..d426dc95517c 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -214,7 +214,7 @@ static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 /*
  * lower_offset_for_folio
  *
- * Convert an eCryptfs page index into a lower byte offset
+ * Convert an eCryptfs folio index into a lower byte offset
  */
 static loff_t lower_offset_for_folio(struct ecryptfs_crypt_stat *crypt_stat,
 				    struct folio *folio)
@@ -263,9 +263,8 @@ static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 	rc = crypt_scatterlist(crypt_stat, dst_sgp, &src_sg, extent_size,
 			       extent_iv, op);
 	if (rc < 0) {
-		printk(KERN_ERR "%s: Error attempting to crypt page with "
-		       "page_index = [%ld], extent_offset = [%ld]; "
-		       "rc = [%d]\n", __func__, page_index, extent_offset, rc);
+		pr_err("%s: Error attempting to crypt folio with page_index = [%ld], extent_offset = [%ld]; rc = [%d]\n",
+		       __func__, page_index, extent_offset, rc);
 		goto out;
 	}
 	rc = 0;
@@ -279,8 +278,8 @@ static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
  *        decrypted content that needs to be encrypted (to a temporary
  *        buffer; not in place) and written out to the lower file
  *
- * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
- * that eCryptfs pages may straddle the lower pages -- for instance,
+ * Encrypt an eCryptfs folio. This is done on a per-extent basis. Note
+ * that eCryptfs folios may straddle the lower pages -- for instance,
  * if the file was created on a machine with an 8K page size
  * (resulting in an 8K header), and then the file is copied onto a
  * host with a 32K page size, then when reading page 0 of the eCryptfs
@@ -341,10 +340,10 @@ int ecryptfs_encrypt_folio(struct folio *folio)
  * ecryptfs_decrypt_folio
  * @folio: Folio mapped from the eCryptfs inode for the file; data read
  *        and decrypted from the lower file will be written into this
- *        page
+ *        folio
  *
- * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
- * that eCryptfs pages may straddle the lower pages -- for instance,
+ * Decrypt an eCryptfs folio. This is done on a per-extent basis. Note
+ * that eCryptfs folios may straddle the lower pages -- for instance,
  * if the file was created on a machine with an 8K page size
  * (resulting in an 8K header), and then the file is copied onto a
  * host with a 32K page size, then when reading page 0 of the eCryptfs
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index d841610644ed..305231cd5336 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -188,16 +188,16 @@ static int ecryptfs_read_folio(struct file *file, struct folio *folio)
 					folio->index, 0, folio_size(folio),
 					inode);
 			if (err) {
-				printk(KERN_ERR "Error reading page; err = "
-				       "[%d]\n", err);
+				pr_err("Error reading folio; err = [%d]\n",
+				       err);
 				goto out;
 			}
 		}
 	} else {
 		err = ecryptfs_decrypt_folio(folio);
 		if (err) {
-			ecryptfs_printk(KERN_ERR, "Error decrypting page; "
-					"err = [%d]\n", err);
+			ecryptfs_printk(KERN_ERR, "Error decrypting folio; err = [%d]\n",
+					err);
 			goto out;
 		}
 	}
@@ -264,8 +264,7 @@ static int ecryptfs_write_begin(const struct kiocb *iocb,
 			rc = ecryptfs_read_lower_folio_segment(
 				folio, index, 0, PAGE_SIZE, mapping->host);
 			if (rc) {
-				printk(KERN_ERR "%s: Error attempting to read "
-				       "lower page segment; rc = [%d]\n",
+				pr_err("%s: Error attempting to read lower folio segment; rc = [%d]\n",
 				       __func__, rc);
 				folio_clear_uptodate(folio);
 				goto out;
@@ -291,8 +290,7 @@ static int ecryptfs_write_begin(const struct kiocb *iocb,
 					folio, index, 0, PAGE_SIZE,
 					mapping->host);
 				if (rc) {
-					printk(KERN_ERR "%s: Error reading "
-					       "page; rc = [%d]\n",
+					pr_err("%s: Error reading folio; rc = [%d]\n",
 					       __func__, rc);
 					folio_clear_uptodate(folio);
 					goto out;
@@ -307,9 +305,7 @@ static int ecryptfs_write_begin(const struct kiocb *iocb,
 			} else if (len < PAGE_SIZE) {
 				rc = ecryptfs_decrypt_folio(folio);
 				if (rc) {
-					printk(KERN_ERR "%s: Error decrypting "
-					       "page at index [%ld]; "
-					       "rc = [%d]\n",
+					pr_err("%s: Error decrypting folio at index [%ld]; rc = [%d]\n",
 					       __func__, folio->index, rc);
 					folio_clear_uptodate(folio);
 					goto out;
@@ -333,8 +329,10 @@ static int ecryptfs_write_begin(const struct kiocb *iocb,
 			}
 		}
 	}
-	/* Writing to a new page, and creating a small hole from start
-	 * of page?  Zero it out. */
+	/*
+	 * Writing to a new folio, and creating a small hole from start
+	 * of folio? Zero it out.
+	 */
 	if ((i_size_read(mapping->host) == prev_page_end_size)
 	    && (pos != 0))
 		folio_zero_range(folio, 0, PAGE_SIZE);
@@ -443,8 +441,8 @@ static int ecryptfs_write_end(const struct kiocb *iocb,
 		&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 	int rc;
 
-	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_folio"
-			"(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
+	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_folio(folio w/ index = [0x%.16lx], to = [%d])\n",
+			index, to);
 	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 		rc = ecryptfs_write_lower_folio_segment(ecryptfs_inode,
 				folio, 0, to);
@@ -465,14 +463,14 @@ static int ecryptfs_write_end(const struct kiocb *iocb,
 	/* Fills in zeros if 'to' goes beyond inode size */
 	rc = fill_zeros_to_end_of_folio(folio, to);
 	if (rc) {
-		ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
-			"zeros in page with index = [0x%.16lx]\n", index);
+		ecryptfs_printk(KERN_WARNING, "Error attempting to fill zeros in folio with index = [0x%.16lx]\n",
+				index);
 		goto out;
 	}
 	rc = ecryptfs_encrypt_folio(folio);
 	if (rc) {
-		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
-				"index [0x%.16lx])\n", index);
+		ecryptfs_printk(KERN_WARNING, "Error encrypting folio (upper index [0x%.16lx])\n",
+				index);
 		goto out;
 	}
 	if (pos + copied > i_size_read(ecryptfs_inode)) {
diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
index 611f74061441..a1949c769225 100644
--- a/fs/ecryptfs/read_write.c
+++ b/fs/ecryptfs/read_write.c
@@ -48,8 +48,8 @@ int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
  * @size: The amount of data from @folio_for_lower to write to the
  *        lower file
  *
- * Determines the byte offset in the file for the given page and
- * offset within the page, maps the page, and makes the call to write
+ * Determines the byte offset in the file for the given folio and
+ * offset within the folio, maps the folio, and makes the call to write
  * the contents of @folio_for_lower to the lower inode.
  *
  * Returns zero on success; non-zero otherwise
@@ -80,7 +80,7 @@ int ecryptfs_write_lower_folio_segment(struct inode *ecryptfs_inode,
  * @size: The number of bytes to write from @data
  *
  * Write an arbitrary amount of data to an arbitrary location in the
- * eCryptfs inode page cache. This is done on a page-by-page, and then
+ * eCryptfs inode page cache. This is done on a folio-by-folio, and then
  * by an extent-by-extent, basis; individual extents are encrypted and
  * written to the lower page cache (via VFS writes). This function
  * takes care of all the address translation to locations in the lower
@@ -133,10 +133,8 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
 				ecryptfs_page_idx, NULL);
 		if (IS_ERR(ecryptfs_folio)) {
 			rc = PTR_ERR(ecryptfs_folio);
-			printk(KERN_ERR "%s: Error getting page at "
-			       "index [%ld] from eCryptfs inode "
-			       "mapping; rc = [%d]\n", __func__,
-			       ecryptfs_page_idx, rc);
+			pr_err("%s: Error getting folio at index [%ld] from eCryptfs inode mapping; rc = [%d]\n",
+			       __func__, ecryptfs_page_idx, rc);
 			goto out;
 		}
 		folio_lock(ecryptfs_folio);
@@ -146,11 +144,13 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
 		 * pos: where we're now writing, offset: where the request was
 		 * If current pos is before request, we are filling zeros
 		 * If we are at or beyond request, we are writing the *data*
-		 * If we're in a fresh page beyond eof, zero it in either case
+		 * If we're in a fresh folio beyond eof, zero it in either case
 		 */
 		if (pos < offset || !start_offset_in_page) {
-			/* We are extending past the previous end of the file.
-			 * Fill in zero values to the end of the page */
+			/*
+			 * We are extending past the previous end of the file.
+			 * Fill in zero values to the end of the folio.
+			 */
 			memset(((char *)ecryptfs_page_virt
 				+ start_offset_in_page), 0,
 				PAGE_SIZE - start_offset_in_page);
@@ -176,8 +176,8 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
 						data_offset);
 		folio_put(ecryptfs_folio);
 		if (rc) {
-			printk(KERN_ERR "%s: Error encrypting "
-			       "page; rc = [%d]\n", __func__, rc);
+			pr_err("%s: Error encrypting folio; rc = [%d]\n",
+			       __func__, rc);
 			goto out;
 		}
 		pos += num_bytes;
@@ -230,16 +230,16 @@ int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
  * ecryptfs_read_lower_folio_segment
  * @folio_for_ecryptfs: The folio into which data for eCryptfs will be
  *                     written
- * @page_index: Page index in @page_for_ecryptfs from which to start
+ * @page_index: Page index in @folio_for_ecryptfs from which to start
  *		writing
- * @offset_in_page: Offset in @page_for_ecryptfs from which to start
+ * @offset_in_page: Offset in @folio_for_ecryptfs from which to start
  *                  writing
- * @size: The number of bytes to write into @page_for_ecryptfs
+ * @size: The number of bytes to write into @folio_for_ecryptfs
  * @ecryptfs_inode: The eCryptfs inode
  *
- * Determines the byte offset in the file for the given page and
- * offset within the page, maps the page, and makes the call to read
- * the contents of @page_for_ecryptfs from the lower inode.
+ * Determines the byte offset in the file for the given folio and
+ * offset within the folio, maps the folio, and makes the call to read
+ * the contents of @folio_for_ecryptfs from the lower inode.
  *
  * Returns zero on success; non-zero otherwise
  */

-- 
2.39.5

Re: [PATCH 0/7] ecryptfs: remove the remaining struct page usage

[Tal Zussman]

On 10/14/26 9:35 PM, Tal Zussman wrote:
> Convert the page cache side of the encryption path to folios, and use
> plain kernel memory for the buffers that were only pages because of the
> old interfaces: the ciphertext block, the header buffer from
> ecryptfs_get_zeroed_pages(), and the scatterlists built by
> virt_to_scatterlist(). Also make a shrinking truncate zero the tail of
> the last folio in place, as other filesystems do, instead of copying
> from the zero page through the write path. After this, fs/ecryptfs has
> no struct page usage left.
> 
> Ran cleanly with fsx and fsstress on ecryptfs over ext4 in the default,
> xattr, and passthrough mount options.
> 
> ---
> Tal Zussman (7):
>       ecryptfs: remove struct ecryptfs_page_crypt_context
>       ecryptfs: use a folio and a buffer in crypt_extent()
>       ecryptfs: use kzalloc() for the header buffer
>       ecryptfs: use sg_init_one() instead of virt_to_scatterlist()
>       ecryptfs: zero the tail of the last folio in place on truncate
>       ecryptfs: rename functions to refer to folios
>       ecryptfs: refer to folios in comments and printk strings
> 

Sashiko found some issues with patches 4 and 5. I'll send v2 with fixes
soon.

Thanks,
Tal