[PATCH v2 00/14] fscrypt, ext4: prepare for blocksize != PAGE_SIZE

[PATCH v2 00/14] fscrypt, ext4: prepare for blocksize != PAGE_SIZE

[Eric Biggers]

Hello,

This patchset prepares fs/crypto/, and partially ext4, for the
'blocksize != PAGE_SIZE' case.

This basically contains the encryption changes from Chandan Rajendra's
patchset "[V2,00/13] Consolidate FS read I/O callbacks code"
(https://patchwork.kernel.org/project/linux-fscrypt/list/?series=111039)
that don't require introducing the read_callbacks and don't depend on
fsverity stuff.  But they've been reworked to clean things up a lot.

I'd like to apply this patchset for 5.3 in order to make things forward
for ext4 encryption with 'blocksize != PAGE_SIZE'.

AFAICT, after this patchset the only thing stopping ext4 encryption from
working with blocksize != PAGE_SIZE is the lack of encryption support in
block_read_full_page(), which the read_callbacks will address.

This patchset applies to v5.2-rc1, and it can also be retrieved from git
at https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git
branch "fscrypt-subpage-blocks-prep".

Changed since v1 (minor cleanups only):

- In "fscrypt: simplify bounce page handling", also remove
  the definition of FS_CTX_HAS_BOUNCE_BUFFER_FL.

- In "ext4: decrypt only the needed blocks in ext4_block_write_begin()",
  simplify the code slightly by moving the IS_ENCRYPTED() check.

- Change __fscrypt_decrypt_bio() in a separate patch rather than as part
  of "fscrypt: support decrypting multiple filesystem blocks per page".
  The resulting code is the same, so I kept Chandan's Reviewed-by.

- Improve the commit message of
  "fscrypt: introduce fscrypt_decrypt_block_inplace()".

Chandan Rajendra (3):
  ext4: clear BH_Uptodate flag on decryption error
  ext4: decrypt only the needed blocks in ext4_block_write_begin()
  ext4: decrypt only the needed block in __ext4_block_zero_page_range()

Eric Biggers (11):
  fscrypt: simplify bounce page handling
  fscrypt: remove the "write" part of struct fscrypt_ctx
  fscrypt: rename fscrypt_do_page_crypto() to fscrypt_crypt_block()
  fscrypt: clean up some BUG_ON()s in block encryption/decryption
  fscrypt: introduce fscrypt_encrypt_block_inplace()
  fscrypt: support encrypting multiple filesystem blocks per page
  fscrypt: handle blocksize < PAGE_SIZE in fscrypt_zeroout_range()
  fscrypt: introduce fscrypt_decrypt_block_inplace()
  fscrypt: support decrypting multiple filesystem blocks per page
  fscrypt: decrypt only the needed blocks in __fscrypt_decrypt_bio()
  ext4: encrypt only up to last block in ext4_bio_write_page()

 fs/crypto/bio.c             |  73 +++------
 fs/crypto/crypto.c          | 299 ++++++++++++++++++++----------------
 fs/crypto/fscrypt_private.h |  15 +-
 fs/ext4/inode.c             |  37 +++--
 fs/ext4/page-io.c           |  44 +++---
 fs/f2fs/data.c              |  17 +-
 fs/ubifs/crypto.c           |  19 +--
 include/linux/fscrypt.h     |  96 ++++++++----
 8 files changed, 319 insertions(+), 281 deletions(-)

-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 01/14] fscrypt: simplify bounce page handling

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Currently, bounce page handling for writes to encrypted files is
unnecessarily complicated.  A fscrypt_ctx is allocated along with each
bounce page, page_private(bounce_page) points to this fscrypt_ctx, and
fscrypt_ctx::w::control_page points to the original pagecache page.

However, because writes don't use the fscrypt_ctx for anything else,
there's no reason why page_private(bounce_page) can't just point to the
original pagecache page directly.

Therefore, this patch makes this change.  In the process, it also cleans
up the API exposed to filesystems that allows testing whether a page is
a bounce page, getting the pagecache page from a bounce page, and
freeing a bounce page.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/bio.c             |  38 ++-----------
 fs/crypto/crypto.c          | 104 ++++++++++++------------------------
 fs/crypto/fscrypt_private.h |   4 +-
 fs/ext4/page-io.c           |  36 +++++--------
 fs/f2fs/data.c              |  12 ++---
 include/linux/fscrypt.h     |  38 ++++++++-----
 6 files changed, 84 insertions(+), 148 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index b46021ebde856..c857b70b5328c 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -70,46 +70,18 @@ void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx, struct bio *bio)
 }
 EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio);
 
-void fscrypt_pullback_bio_page(struct page **page, bool restore)
-{
-	struct fscrypt_ctx *ctx;
-	struct page *bounce_page;
-
-	/* The bounce data pages are unmapped. */
-	if ((*page)->mapping)
-		return;
-
-	/* The bounce data page is unmapped. */
-	bounce_page = *page;
-	ctx = (struct fscrypt_ctx *)page_private(bounce_page);
-
-	/* restore control page */
-	*page = ctx->w.control_page;
-
-	if (restore)
-		fscrypt_restore_control_page(bounce_page);
-}
-EXPORT_SYMBOL(fscrypt_pullback_bio_page);
-
 int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 				sector_t pblk, unsigned int len)
 {
-	struct fscrypt_ctx *ctx;
-	struct page *ciphertext_page = NULL;
+	struct page *ciphertext_page;
 	struct bio *bio;
 	int ret, err = 0;
 
 	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
 
-	ctx = fscrypt_get_ctx(GFP_NOFS);
-	if (IS_ERR(ctx))
-		return PTR_ERR(ctx);
-
-	ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT);
-	if (IS_ERR(ciphertext_page)) {
-		err = PTR_ERR(ciphertext_page);
-		goto errout;
-	}
+	ciphertext_page = fscrypt_alloc_bounce_page(GFP_NOWAIT);
+	if (!ciphertext_page)
+		return -ENOMEM;
 
 	while (len--) {
 		err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk,
@@ -147,7 +119,7 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 	}
 	err = 0;
 errout:
-	fscrypt_release_ctx(ctx);
+	fscrypt_free_bounce_page(ciphertext_page);
 	return err;
 }
 EXPORT_SYMBOL(fscrypt_zeroout_range);
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 68e2ca4c4af63..4b076f8daab75 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -63,18 +63,11 @@ EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
  *
  * If the encryption context was allocated from the pre-allocated pool, returns
  * it to that pool. Else, frees it.
- *
- * If there's a bounce page in the context, this frees that.
  */
 void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
 {
 	unsigned long flags;
 
-	if (ctx->flags & FS_CTX_HAS_BOUNCE_BUFFER_FL && ctx->w.bounce_page) {
-		mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool);
-		ctx->w.bounce_page = NULL;
-	}
-	ctx->w.control_page = NULL;
 	if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
 		kmem_cache_free(fscrypt_ctx_cachep, ctx);
 	} else {
@@ -99,14 +92,8 @@ struct fscrypt_ctx *fscrypt_get_ctx(gfp_t gfp_flags)
 	unsigned long flags;
 
 	/*
-	 * We first try getting the ctx from a free list because in
-	 * the common case the ctx will have an allocated and
-	 * initialized crypto tfm, so it's probably a worthwhile
-	 * optimization. For the bounce page, we first try getting it
-	 * from the kernel allocator because that's just about as fast
-	 * as getting it from a list and because a cache of free pages
-	 * should generally be a "last resort" option for a filesystem
-	 * to be able to do its job.
+	 * First try getting a ctx from the free list so that we don't have to
+	 * call into the slab allocator.
 	 */
 	spin_lock_irqsave(&fscrypt_ctx_lock, flags);
 	ctx = list_first_entry_or_null(&fscrypt_free_ctxs,
@@ -122,11 +109,31 @@ struct fscrypt_ctx *fscrypt_get_ctx(gfp_t gfp_flags)
 	} else {
 		ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
 	}
-	ctx->flags &= ~FS_CTX_HAS_BOUNCE_BUFFER_FL;
 	return ctx;
 }
 EXPORT_SYMBOL(fscrypt_get_ctx);
 
+struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
+{
+	return mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
+}
+
+/**
+ * fscrypt_free_bounce_page() - free a ciphertext bounce page
+ *
+ * Free a bounce page that was allocated by fscrypt_encrypt_page(), or by
+ * fscrypt_alloc_bounce_page() directly.
+ */
+void fscrypt_free_bounce_page(struct page *bounce_page)
+{
+	if (!bounce_page)
+		return;
+	set_page_private(bounce_page, (unsigned long)NULL);
+	ClearPagePrivate(bounce_page);
+	mempool_free(bounce_page, fscrypt_bounce_page_pool);
+}
+EXPORT_SYMBOL(fscrypt_free_bounce_page);
+
 void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
 			 const struct fscrypt_info *ci)
 {
@@ -185,16 +192,6 @@ int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
 	return 0;
 }
 
-struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
-				       gfp_t gfp_flags)
-{
-	ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
-	if (ctx->w.bounce_page == NULL)
-		return ERR_PTR(-ENOMEM);
-	ctx->flags |= FS_CTX_HAS_BOUNCE_BUFFER_FL;
-	return ctx->w.bounce_page;
-}
-
 /**
  * fscypt_encrypt_page() - Encrypts a page
  * @inode:     The inode for which the encryption should take place
@@ -209,22 +206,12 @@ struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
  *             previously written data.
  * @gfp_flags: The gfp flag for memory allocation
  *
- * Encrypts @page using the ctx encryption context. Performs encryption
- * either in-place or into a newly allocated bounce page.
- * Called on the page write path.
- *
- * Bounce page allocation is the default.
- * In this case, the contents of @page are encrypted and stored in an
- * allocated bounce page. @page has to be locked and the caller must call
- * fscrypt_restore_control_page() on the returned ciphertext page to
- * release the bounce buffer and the encryption context.
- *
- * In-place encryption is used by setting the FS_CFLG_OWN_PAGES flag in
- * fscrypt_operations. Here, the input-page is returned with its content
- * encrypted.
+ * Encrypts @page.  If the filesystem set FS_CFLG_OWN_PAGES, then the data is
+ * encrypted in-place and @page is returned.  Else, a bounce page is allocated,
+ * the data is encrypted into the bounce page, and the bounce page is returned.
+ * The caller is responsible for calling fscrypt_free_bounce_page().
  *
- * Return: A page with the encrypted content on success. Else, an
- * error value or NULL.
+ * Return: A page containing the encrypted data on success, else an ERR_PTR()
  */
 struct page *fscrypt_encrypt_page(const struct inode *inode,
 				struct page *page,
@@ -233,7 +220,6 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 				u64 lblk_num, gfp_t gfp_flags)
 
 {
-	struct fscrypt_ctx *ctx;
 	struct page *ciphertext_page = page;
 	int err;
 
@@ -252,30 +238,20 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 
 	BUG_ON(!PageLocked(page));
 
-	ctx = fscrypt_get_ctx(gfp_flags);
-	if (IS_ERR(ctx))
-		return ERR_CAST(ctx);
-
 	/* The encryption operation will require a bounce page. */
-	ciphertext_page = fscrypt_alloc_bounce_page(ctx, gfp_flags);
-	if (IS_ERR(ciphertext_page))
-		goto errout;
+	ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
+	if (!ciphertext_page)
+		return ERR_PTR(-ENOMEM);
 
-	ctx->w.control_page = page;
 	err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num,
 				     page, ciphertext_page, len, offs,
 				     gfp_flags);
 	if (err) {
-		ciphertext_page = ERR_PTR(err);
-		goto errout;
+		fscrypt_free_bounce_page(ciphertext_page);
+		return ERR_PTR(err);
 	}
 	SetPagePrivate(ciphertext_page);
-	set_page_private(ciphertext_page, (unsigned long)ctx);
-	lock_page(ciphertext_page);
-	return ciphertext_page;
-
-errout:
-	fscrypt_release_ctx(ctx);
+	set_page_private(ciphertext_page, (unsigned long)page);
 	return ciphertext_page;
 }
 EXPORT_SYMBOL(fscrypt_encrypt_page);
@@ -354,18 +330,6 @@ const struct dentry_operations fscrypt_d_ops = {
 	.d_revalidate = fscrypt_d_revalidate,
 };
 
-void fscrypt_restore_control_page(struct page *page)
-{
-	struct fscrypt_ctx *ctx;
-
-	ctx = (struct fscrypt_ctx *)page_private(page);
-	set_page_private(page, (unsigned long)NULL);
-	ClearPagePrivate(page);
-	unlock_page(page);
-	fscrypt_release_ctx(ctx);
-}
-EXPORT_SYMBOL(fscrypt_restore_control_page);
-
 static void fscrypt_destroy(void)
 {
 	struct fscrypt_ctx *pos, *n;
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 7da2761595933..4122ee1a0b7b1 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -94,7 +94,6 @@ typedef enum {
 } fscrypt_direction_t;
 
 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL		0x00000001
-#define FS_CTX_HAS_BOUNCE_BUFFER_FL		0x00000002
 
 static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
 					   u32 filenames_mode)
@@ -123,8 +122,7 @@ extern int fscrypt_do_page_crypto(const struct inode *inode,
 				  struct page *dest_page,
 				  unsigned int len, unsigned int offs,
 				  gfp_t gfp_flags);
-extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
-					      gfp_t gfp_flags);
+extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
 extern const struct dentry_operations fscrypt_d_ops;
 
 extern void __printf(3, 4) __cold
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 4690618a92e93..13d5ecc0af03f 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -66,9 +66,7 @@ static void ext4_finish_bio(struct bio *bio)
 
 	bio_for_each_segment_all(bvec, bio, iter_all) {
 		struct page *page = bvec->bv_page;
-#ifdef CONFIG_FS_ENCRYPTION
-		struct page *data_page = NULL;
-#endif
+		struct page *bounce_page = NULL;
 		struct buffer_head *bh, *head;
 		unsigned bio_start = bvec->bv_offset;
 		unsigned bio_end = bio_start + bvec->bv_len;
@@ -78,13 +76,10 @@ static void ext4_finish_bio(struct bio *bio)
 		if (!page)
 			continue;
 
-#ifdef CONFIG_FS_ENCRYPTION
-		if (!page->mapping) {
-			/* The bounce data pages are unmapped. */
-			data_page = page;
-			fscrypt_pullback_bio_page(&page, false);
+		if (fscrypt_is_bounce_page(page)) {
+			bounce_page = page;
+			page = fscrypt_pagecache_page(bounce_page);
 		}
-#endif
 
 		if (bio->bi_status) {
 			SetPageError(page);
@@ -111,10 +106,7 @@ static void ext4_finish_bio(struct bio *bio)
 		bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
 		local_irq_restore(flags);
 		if (!under_io) {
-#ifdef CONFIG_FS_ENCRYPTION
-			if (data_page)
-				fscrypt_restore_control_page(data_page);
-#endif
+			fscrypt_free_bounce_page(bounce_page);
 			end_page_writeback(page);
 		}
 	}
@@ -415,7 +407,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 			struct writeback_control *wbc,
 			bool keep_towrite)
 {
-	struct page *data_page = NULL;
+	struct page *bounce_page = NULL;
 	struct inode *inode = page->mapping->host;
 	unsigned block_start;
 	struct buffer_head *bh, *head;
@@ -479,10 +471,10 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 		gfp_t gfp_flags = GFP_NOFS;
 
 	retry_encrypt:
-		data_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0,
-						page->index, gfp_flags);
-		if (IS_ERR(data_page)) {
-			ret = PTR_ERR(data_page);
+		bounce_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0,
+						   page->index, gfp_flags);
+		if (IS_ERR(bounce_page)) {
+			ret = PTR_ERR(bounce_page);
 			if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
 				if (io->io_bio) {
 					ext4_io_submit(io);
@@ -491,7 +483,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 				gfp_flags |= __GFP_NOFAIL;
 				goto retry_encrypt;
 			}
-			data_page = NULL;
+			bounce_page = NULL;
 			goto out;
 		}
 	}
@@ -500,8 +492,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 	do {
 		if (!buffer_async_write(bh))
 			continue;
-		ret = io_submit_add_bh(io, inode,
-				       data_page ? data_page : page, bh);
+		ret = io_submit_add_bh(io, inode, bounce_page ?: page, bh);
 		if (ret) {
 			/*
 			 * We only get here on ENOMEM.  Not much else
@@ -517,8 +508,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 	/* Error stopped previous loop? Clean up buffers... */
 	if (ret) {
 	out:
-		if (data_page)
-			fscrypt_restore_control_page(data_page);
+		fscrypt_free_bounce_page(bounce_page);
 		printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
 		redirty_page_for_writepage(wbc, page);
 		do {
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index eda4181d20926..968ebdbcb5834 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -185,7 +185,7 @@ static void f2fs_write_end_io(struct bio *bio)
 			continue;
 		}
 
-		fscrypt_pullback_bio_page(&page, true);
+		fscrypt_finalize_bounce_page(&page);
 
 		if (unlikely(bio->bi_status)) {
 			mapping_set_error(page->mapping, -EIO);
@@ -362,10 +362,9 @@ static bool __has_merged_page(struct f2fs_bio_info *io, struct inode *inode,
 
 	bio_for_each_segment_all(bvec, io->bio, iter_all) {
 
-		if (bvec->bv_page->mapping)
-			target = bvec->bv_page;
-		else
-			target = fscrypt_control_page(bvec->bv_page);
+		target = bvec->bv_page;
+		if (fscrypt_is_bounce_page(target))
+			target = fscrypt_pagecache_page(target);
 
 		if (inode && inode == target->mapping->host)
 			return true;
@@ -1900,8 +1899,7 @@ int f2fs_do_write_data_page(struct f2fs_io_info *fio)
 		err = f2fs_inplace_write_data(fio);
 		if (err) {
 			if (f2fs_encrypted_file(inode))
-				fscrypt_pullback_bio_page(&fio->encrypted_page,
-									true);
+				fscrypt_finalize_bounce_page(&fio->encrypted_page);
 			if (PageWriteback(page))
 				end_page_writeback(page);
 		} else {
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index f7680ef1abd2d..d016fa384d607 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -112,12 +112,17 @@ extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
 extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
 				unsigned int, u64);
 
-static inline struct page *fscrypt_control_page(struct page *page)
+static inline bool fscrypt_is_bounce_page(struct page *page)
 {
-	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
+	return page->mapping == NULL;
 }
 
-extern void fscrypt_restore_control_page(struct page *);
+static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
+{
+	return (struct page *)page_private(bounce_page);
+}
+
+extern void fscrypt_free_bounce_page(struct page *bounce_page);
 
 /* policy.c */
 extern int fscrypt_ioctl_set_policy(struct file *, const void __user *);
@@ -223,7 +228,6 @@ static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
 extern void fscrypt_decrypt_bio(struct bio *);
 extern void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
 					struct bio *bio);
-extern void fscrypt_pullback_bio_page(struct page **, bool);
 extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
 				 unsigned int);
 
@@ -300,15 +304,19 @@ static inline int fscrypt_decrypt_page(const struct inode *inode,
 	return -EOPNOTSUPP;
 }
 
-static inline struct page *fscrypt_control_page(struct page *page)
+static inline bool fscrypt_is_bounce_page(struct page *page)
+{
+	return false;
+}
+
+static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
 {
 	WARN_ON_ONCE(1);
 	return ERR_PTR(-EINVAL);
 }
 
-static inline void fscrypt_restore_control_page(struct page *page)
+static inline void fscrypt_free_bounce_page(struct page *bounce_page)
 {
-	return;
 }
 
 /* policy.c */
@@ -410,11 +418,6 @@ static inline void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
 {
 }
 
-static inline void fscrypt_pullback_bio_page(struct page **page, bool restore)
-{
-	return;
-}
-
 static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 					sector_t pblk, unsigned int len)
 {
@@ -692,4 +695,15 @@ static inline int fscrypt_encrypt_symlink(struct inode *inode,
 	return 0;
 }
 
+/* If *pagep is a bounce page, free it and set *pagep to the pagecache page */
+static inline void fscrypt_finalize_bounce_page(struct page **pagep)
+{
+	struct page *page = *pagep;
+
+	if (fscrypt_is_bounce_page(page)) {
+		*pagep = fscrypt_pagecache_page(page);
+		fscrypt_free_bounce_page(page);
+	}
+}
+
 #endif	/* _LINUX_FSCRYPT_H */
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 02/14] fscrypt: remove the "write" part of struct fscrypt_ctx

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Now that fscrypt_ctx is not used for writes, remove the 'w' fields.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/bio.c         | 11 +++++------
 fs/crypto/crypto.c      | 14 +++++++-------
 include/linux/fscrypt.h |  7 ++-----
 3 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index c857b70b5328c..c534253483874 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -53,9 +53,8 @@ EXPORT_SYMBOL(fscrypt_decrypt_bio);
 
 static void completion_pages(struct work_struct *work)
 {
-	struct fscrypt_ctx *ctx =
-		container_of(work, struct fscrypt_ctx, r.work);
-	struct bio *bio = ctx->r.bio;
+	struct fscrypt_ctx *ctx = container_of(work, struct fscrypt_ctx, work);
+	struct bio *bio = ctx->bio;
 
 	__fscrypt_decrypt_bio(bio, true);
 	fscrypt_release_ctx(ctx);
@@ -64,9 +63,9 @@ static void completion_pages(struct work_struct *work)
 
 void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx, struct bio *bio)
 {
-	INIT_WORK(&ctx->r.work, completion_pages);
-	ctx->r.bio = bio;
-	fscrypt_enqueue_decrypt_work(&ctx->r.work);
+	INIT_WORK(&ctx->work, completion_pages);
+	ctx->bio = bio;
+	fscrypt_enqueue_decrypt_work(&ctx->work);
 }
 EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio);
 
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 4b076f8daab75..ebfa13cfecb7d 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -58,11 +58,11 @@ void fscrypt_enqueue_decrypt_work(struct work_struct *work)
 EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
 
 /**
- * fscrypt_release_ctx() - Releases an encryption context
- * @ctx: The encryption context to release.
+ * fscrypt_release_ctx() - Release a decryption context
+ * @ctx: The decryption context to release.
  *
- * If the encryption context was allocated from the pre-allocated pool, returns
- * it to that pool. Else, frees it.
+ * If the decryption context was allocated from the pre-allocated pool, return
+ * it to that pool.  Else, free it.
  */
 void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
 {
@@ -79,12 +79,12 @@ void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
 EXPORT_SYMBOL(fscrypt_release_ctx);
 
 /**
- * fscrypt_get_ctx() - Gets an encryption context
+ * fscrypt_get_ctx() - Get a decryption context
  * @gfp_flags:   The gfp flag for memory allocation
  *
- * Allocates and initializes an encryption context.
+ * Allocate and initialize a decryption context.
  *
- * Return: A new encryption context on success; an ERR_PTR() otherwise.
+ * Return: A new decryption context on success; an ERR_PTR() otherwise.
  */
 struct fscrypt_ctx *fscrypt_get_ctx(gfp_t gfp_flags)
 {
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index d016fa384d607..1c7287f146a98 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -63,16 +63,13 @@ struct fscrypt_operations {
 	unsigned int max_namelen;
 };
 
+/* Decryption work */
 struct fscrypt_ctx {
 	union {
-		struct {
-			struct page *bounce_page;	/* Ciphertext page */
-			struct page *control_page;	/* Original page  */
-		} w;
 		struct {
 			struct bio *bio;
 			struct work_struct work;
-		} r;
+		};
 		struct list_head free_list;	/* Free list */
 	};
 	u8 flags;				/* Flags */
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 03/14] fscrypt: rename fscrypt_do_page_crypto() to fscrypt_crypt_block()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

fscrypt_do_page_crypto() only does a single encryption or decryption
operation, with a single logical block number (single IV).  So it
actually operates on a filesystem block, not a "page" per se.  To
reflect this, rename it to fscrypt_crypt_block().

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/bio.c             |  6 +++---
 fs/crypto/crypto.c          | 24 ++++++++++++------------
 fs/crypto/fscrypt_private.h | 11 +++++------
 3 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index c534253483874..92b2d5da5d8e1 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -83,9 +83,9 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 		return -ENOMEM;
 
 	while (len--) {
-		err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk,
-					     ZERO_PAGE(0), ciphertext_page,
-					     PAGE_SIZE, 0, GFP_NOFS);
+		err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,
+					  ZERO_PAGE(0), ciphertext_page,
+					  PAGE_SIZE, 0, GFP_NOFS);
 		if (err)
 			goto errout;
 
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index ebfa13cfecb7d..e6802d7aca3c7 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -147,10 +147,11 @@ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
 		crypto_cipher_encrypt_one(ci->ci_essiv_tfm, iv->raw, iv->raw);
 }
 
-int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
-			   u64 lblk_num, struct page *src_page,
-			   struct page *dest_page, unsigned int len,
-			   unsigned int offs, gfp_t gfp_flags)
+/* Encrypt or decrypt a single filesystem block of file contents */
+int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
+			u64 lblk_num, struct page *src_page,
+			struct page *dest_page, unsigned int len,
+			unsigned int offs, gfp_t gfp_flags)
 {
 	union fscrypt_iv iv;
 	struct skcipher_request *req = NULL;
@@ -227,9 +228,9 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 
 	if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
 		/* with inplace-encryption we just encrypt the page */
-		err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num, page,
-					     ciphertext_page, len, offs,
-					     gfp_flags);
+		err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page,
+					  ciphertext_page, len, offs,
+					  gfp_flags);
 		if (err)
 			return ERR_PTR(err);
 
@@ -243,9 +244,8 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 	if (!ciphertext_page)
 		return ERR_PTR(-ENOMEM);
 
-	err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num,
-				     page, ciphertext_page, len, offs,
-				     gfp_flags);
+	err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page,
+				  ciphertext_page, len, offs, gfp_flags);
 	if (err) {
 		fscrypt_free_bounce_page(ciphertext_page);
 		return ERR_PTR(err);
@@ -277,8 +277,8 @@ int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
 	if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES))
 		BUG_ON(!PageLocked(page));
 
-	return fscrypt_do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page,
-				      len, offs, GFP_NOFS);
+	return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
+				   len, offs, GFP_NOFS);
 }
 EXPORT_SYMBOL(fscrypt_decrypt_page);
 
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 4122ee1a0b7b1..8978eec9d766d 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -116,12 +116,11 @@ static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
 /* crypto.c */
 extern struct kmem_cache *fscrypt_info_cachep;
 extern int fscrypt_initialize(unsigned int cop_flags);
-extern int fscrypt_do_page_crypto(const struct inode *inode,
-				  fscrypt_direction_t rw, u64 lblk_num,
-				  struct page *src_page,
-				  struct page *dest_page,
-				  unsigned int len, unsigned int offs,
-				  gfp_t gfp_flags);
+extern int fscrypt_crypt_block(const struct inode *inode,
+			       fscrypt_direction_t rw, u64 lblk_num,
+			       struct page *src_page, struct page *dest_page,
+			       unsigned int len, unsigned int offs,
+			       gfp_t gfp_flags);
 extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
 extern const struct dentry_operations fscrypt_d_ops;
 
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 04/14] fscrypt: clean up some BUG_ON()s in block encryption/decryption

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Replace some BUG_ON()s with WARN_ON_ONCE() and returning an error code,
and move the check for len divisible by FS_CRYPTO_BLOCK_SIZE into
fscrypt_crypt_block() so that it's done for both encryption and
decryption, not just encryption.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/crypto.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index e6802d7aca3c7..9cda0147fca95 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -161,7 +161,10 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
 	struct crypto_skcipher *tfm = ci->ci_ctfm;
 	int res = 0;
 
-	BUG_ON(len == 0);
+	if (WARN_ON_ONCE(len <= 0))
+		return -EINVAL;
+	if (WARN_ON_ONCE(len % FS_CRYPTO_BLOCK_SIZE != 0))
+		return -EINVAL;
 
 	fscrypt_generate_iv(&iv, lblk_num, ci);
 
@@ -224,8 +227,6 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 	struct page *ciphertext_page = page;
 	int err;
 
-	BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0);
-
 	if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
 		/* with inplace-encryption we just encrypt the page */
 		err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page,
@@ -237,7 +238,8 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 		return ciphertext_page;
 	}
 
-	BUG_ON(!PageLocked(page));
+	if (WARN_ON_ONCE(!PageLocked(page)))
+		return ERR_PTR(-EINVAL);
 
 	/* The encryption operation will require a bounce page. */
 	ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
@@ -274,8 +276,9 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
 int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
 			unsigned int len, unsigned int offs, u64 lblk_num)
 {
-	if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES))
-		BUG_ON(!PageLocked(page));
+	if (WARN_ON_ONCE(!PageLocked(page) &&
+			 !(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES)))
+		return -EINVAL;
 
 	return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
 				   len, offs, GFP_NOFS);
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 05/14] fscrypt: introduce fscrypt_encrypt_block_inplace()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

fscrypt_encrypt_page() behaves very differently depending on whether the
filesystem set FS_CFLG_OWN_PAGES in its fscrypt_operations.  This makes
the function difficult to understand and document.  It also makes it so
that all callers have to provide inode and lblk_num, when fscrypt could
determine these itself for pagecache pages.

Therefore, move the FS_CFLG_OWN_PAGES behavior into a new function
fscrypt_encrypt_block_inplace().

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/crypto.c      | 50 +++++++++++++++++++++++++----------------
 fs/ubifs/crypto.c       | 12 +++++-----
 include/linux/fscrypt.h | 13 +++++++++++
 3 files changed, 50 insertions(+), 25 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 9cda0147fca95..6877b7c6165de 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -199,8 +199,7 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
 /**
  * fscypt_encrypt_page() - Encrypts a page
  * @inode:     The inode for which the encryption should take place
- * @page:      The page to encrypt. Must be locked for bounce-page
- *             encryption.
+ * @page:      The page to encrypt. Must be locked.
  * @len:       Length of data to encrypt in @page and encrypted
  *             data in returned page.
  * @offs:      Offset of data within @page and returned
@@ -210,10 +209,9 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
  *             previously written data.
  * @gfp_flags: The gfp flag for memory allocation
  *
- * Encrypts @page.  If the filesystem set FS_CFLG_OWN_PAGES, then the data is
- * encrypted in-place and @page is returned.  Else, a bounce page is allocated,
- * the data is encrypted into the bounce page, and the bounce page is returned.
- * The caller is responsible for calling fscrypt_free_bounce_page().
+ * Encrypts @page.  A bounce page is allocated, the data is encrypted into the
+ * bounce page, and the bounce page is returned.  The caller is responsible for
+ * calling fscrypt_free_bounce_page().
  *
  * Return: A page containing the encrypted data on success, else an ERR_PTR()
  */
@@ -224,24 +222,12 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 				u64 lblk_num, gfp_t gfp_flags)
 
 {
-	struct page *ciphertext_page = page;
+	struct page *ciphertext_page;
 	int err;
 
-	if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
-		/* with inplace-encryption we just encrypt the page */
-		err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page,
-					  ciphertext_page, len, offs,
-					  gfp_flags);
-		if (err)
-			return ERR_PTR(err);
-
-		return ciphertext_page;
-	}
-
 	if (WARN_ON_ONCE(!PageLocked(page)))
 		return ERR_PTR(-EINVAL);
 
-	/* The encryption operation will require a bounce page. */
 	ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
 	if (!ciphertext_page)
 		return ERR_PTR(-ENOMEM);
@@ -258,6 +244,32 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 }
 EXPORT_SYMBOL(fscrypt_encrypt_page);
 
+/**
+ * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place
+ * @inode:     The inode to which this block belongs
+ * @page:      The page containing the block to encrypt
+ * @len:       Size of block to encrypt.  Doesn't need to be a multiple of the
+ *		fs block size, but must be a multiple of FS_CRYPTO_BLOCK_SIZE.
+ * @offs:      Byte offset within @page at which the block to encrypt begins
+ * @lblk_num:  Filesystem logical block number of the block, i.e. the 0-based
+ *		number of the block within the file
+ * @gfp_flags: Memory allocation flags
+ *
+ * Encrypt a possibly-compressed filesystem block that is located in an
+ * arbitrary page, not necessarily in the original pagecache page.  The @inode
+ * and @lblk_num must be specified, as they can't be determined from @page.
+ *
+ * Return: 0 on success; -errno on failure
+ */
+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)
+{
+	return fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page, page,
+				   len, offs, gfp_flags);
+}
+EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
+
 /**
  * fscrypt_decrypt_page() - Decrypts a page in-place
  * @inode:     The corresponding inode for the page to decrypt.
diff --git a/fs/ubifs/crypto.c b/fs/ubifs/crypto.c
index 4aaedf2d7f442..032efdad2e668 100644
--- a/fs/ubifs/crypto.c
+++ b/fs/ubifs/crypto.c
@@ -29,8 +29,8 @@ int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
 {
 	struct ubifs_info *c = inode->i_sb->s_fs_info;
 	void *p = &dn->data;
-	struct page *ret;
 	unsigned int pad_len = round_up(in_len, UBIFS_CIPHER_BLOCK_SIZE);
+	int err;
 
 	ubifs_assert(c, pad_len <= *out_len);
 	dn->compr_size = cpu_to_le16(in_len);
@@ -39,11 +39,11 @@ int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
 	if (pad_len != in_len)
 		memset(p + in_len, 0, pad_len - in_len);
 
-	ret = fscrypt_encrypt_page(inode, virt_to_page(&dn->data), pad_len,
-			offset_in_page(&dn->data), block, GFP_NOFS);
-	if (IS_ERR(ret)) {
-		ubifs_err(c, "fscrypt_encrypt_page failed: %ld", PTR_ERR(ret));
-		return PTR_ERR(ret);
+	err = fscrypt_encrypt_block_inplace(inode, virt_to_page(p), pad_len,
+					    offset_in_page(p), block, GFP_NOFS);
+	if (err) {
+		ubifs_err(c, "fscrypt_encrypt_block_inplace() failed: %d", err);
+		return err;
 	}
 	*out_len = pad_len;
 
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 1c7287f146a98..a9b2d26e615d5 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -106,6 +106,10 @@ extern void fscrypt_release_ctx(struct fscrypt_ctx *);
 extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
 						unsigned int, unsigned int,
 						u64, gfp_t);
+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);
 
@@ -293,6 +297,15 @@ static inline struct page *fscrypt_encrypt_page(const struct inode *inode,
 	return ERR_PTR(-EOPNOTSUPP);
 }
 
+static inline 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)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline int fscrypt_decrypt_page(const struct inode *inode,
 				       struct page *page,
 				       unsigned int len, unsigned int offs,
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 06/14] fscrypt: support encrypting multiple filesystem blocks per page

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Rename fscrypt_encrypt_page() to fscrypt_encrypt_pagecache_blocks() and
redefine its behavior to encrypt all filesystem blocks from the given
region of the given page, rather than assuming that the region consists
of just one filesystem block.  Also remove the 'inode' and 'lblk_num'
parameters, since they can be retrieved from the page as it's already
assumed to be a pagecache page.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

This is based on work by Chandan Rajendra.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/crypto.c      | 67 ++++++++++++++++++++++++-----------------
 fs/ext4/page-io.c       |  4 +--
 fs/f2fs/data.c          |  5 +--
 include/linux/fscrypt.h | 17 ++++++-----
 4 files changed, 53 insertions(+), 40 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 6877b7c6165de..7bdb985126d97 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -121,8 +121,8 @@ struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
 /**
  * fscrypt_free_bounce_page() - free a ciphertext bounce page
  *
- * Free a bounce page that was allocated by fscrypt_encrypt_page(), or by
- * fscrypt_alloc_bounce_page() directly.
+ * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks(),
+ * or by fscrypt_alloc_bounce_page() directly.
  */
 void fscrypt_free_bounce_page(struct page *bounce_page)
 {
@@ -197,52 +197,63 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
 }
 
 /**
- * fscypt_encrypt_page() - Encrypts a page
- * @inode:     The inode for which the encryption should take place
- * @page:      The page to encrypt. Must be locked.
- * @len:       Length of data to encrypt in @page and encrypted
- *             data in returned page.
- * @offs:      Offset of data within @page and returned
- *             page holding encrypted data.
- * @lblk_num:  Logical block number. This must be unique for multiple
- *             calls with same inode, except when overwriting
- *             previously written data.
- * @gfp_flags: The gfp flag for memory allocation
+ * fscrypt_encrypt_pagecache_blocks() - Encrypt filesystem blocks from a pagecache page
+ * @page:      The locked pagecache page containing the block(s) to encrypt
+ * @len:       Total size of the block(s) to encrypt.  Must be a nonzero
+ *		multiple of the filesystem's block size.
+ * @offs:      Byte offset within @page of the first block to encrypt.  Must be
+ *		a multiple of the filesystem's block size.
+ * @gfp_flags: Memory allocation flags
+ *
+ * A new bounce page is allocated, and the specified block(s) are encrypted into
+ * it.  In the bounce page, the ciphertext block(s) will be located at the same
+ * offsets at which the plaintext block(s) were located in the source page; any
+ * other parts of the bounce page will be left uninitialized.  However, normally
+ * blocksize == PAGE_SIZE and the whole page is encrypted at once.
  *
- * Encrypts @page.  A bounce page is allocated, the data is encrypted into the
- * bounce page, and the bounce page is returned.  The caller is responsible for
- * calling fscrypt_free_bounce_page().
+ * This is for use by the filesystem's ->writepages() method.
  *
- * Return: A page containing the encrypted data on success, else an ERR_PTR()
+ * Return: the new encrypted bounce page on success; an ERR_PTR() on failure
  */
-struct page *fscrypt_encrypt_page(const struct inode *inode,
-				struct page *page,
-				unsigned int len,
-				unsigned int offs,
-				u64 lblk_num, gfp_t gfp_flags)
+struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
+					      unsigned int len,
+					      unsigned int offs,
+					      gfp_t gfp_flags)
 
 {
+	const struct inode *inode = page->mapping->host;
+	const unsigned int blockbits = inode->i_blkbits;
+	const unsigned int blocksize = 1 << blockbits;
 	struct page *ciphertext_page;
+	u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) +
+		       (offs >> blockbits);
+	unsigned int i;
 	int err;
 
 	if (WARN_ON_ONCE(!PageLocked(page)))
 		return ERR_PTR(-EINVAL);
 
+	if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
+		return ERR_PTR(-EINVAL);
+
 	ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
 	if (!ciphertext_page)
 		return ERR_PTR(-ENOMEM);
 
-	err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page,
-				  ciphertext_page, len, offs, gfp_flags);
-	if (err) {
-		fscrypt_free_bounce_page(ciphertext_page);
-		return ERR_PTR(err);
+	for (i = offs; i < offs + len; i += blocksize, lblk_num++) {
+		err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num,
+					  page, ciphertext_page,
+					  blocksize, i, gfp_flags);
+		if (err) {
+			fscrypt_free_bounce_page(ciphertext_page);
+			return ERR_PTR(err);
+		}
 	}
 	SetPagePrivate(ciphertext_page);
 	set_page_private(ciphertext_page, (unsigned long)page);
 	return ciphertext_page;
 }
-EXPORT_SYMBOL(fscrypt_encrypt_page);
+EXPORT_SYMBOL(fscrypt_encrypt_pagecache_blocks);
 
 /**
  * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 13d5ecc0af03f..40ee33df57649 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -471,8 +471,8 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 		gfp_t gfp_flags = GFP_NOFS;
 
 	retry_encrypt:
-		bounce_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0,
-						   page->index, gfp_flags);
+		bounce_page = fscrypt_encrypt_pagecache_blocks(page, PAGE_SIZE,
+							       0, gfp_flags);
 		if (IS_ERR(bounce_page)) {
 			ret = PTR_ERR(bounce_page);
 			if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 968ebdbcb5834..a546ac8685ea6 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1726,8 +1726,9 @@ static int encrypt_one_page(struct f2fs_io_info *fio)
 	f2fs_wait_on_block_writeback(inode, fio->old_blkaddr);
 
 retry_encrypt:
-	fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page,
-			PAGE_SIZE, 0, fio->page->index, gfp_flags);
+	fio->encrypted_page = fscrypt_encrypt_pagecache_blocks(fio->page,
+							       PAGE_SIZE, 0,
+							       gfp_flags);
 	if (IS_ERR(fio->encrypted_page)) {
 		/* flush pending IOs and wait for a while in the ENOMEM case */
 		if (PTR_ERR(fio->encrypted_page) == -ENOMEM) {
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index a9b2d26e615d5..c7e16bd16a6c2 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -103,9 +103,11 @@ static inline void fscrypt_handle_d_move(struct dentry *dentry)
 extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
 extern struct fscrypt_ctx *fscrypt_get_ctx(gfp_t);
 extern void fscrypt_release_ctx(struct fscrypt_ctx *);
-extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
-						unsigned int, unsigned int,
-						u64, gfp_t);
+
+extern struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
+						     unsigned int len,
+						     unsigned int offs,
+						     gfp_t gfp_flags);
 extern int fscrypt_encrypt_block_inplace(const struct inode *inode,
 					 struct page *page, unsigned int len,
 					 unsigned int offs, u64 lblk_num,
@@ -288,11 +290,10 @@ static inline void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
 	return;
 }
 
-static inline struct page *fscrypt_encrypt_page(const struct inode *inode,
-						struct page *page,
-						unsigned int len,
-						unsigned int offs,
-						u64 lblk_num, gfp_t gfp_flags)
+static inline struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
+							    unsigned int len,
+							    unsigned int offs,
+							    gfp_t gfp_flags)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 07/14] fscrypt: handle blocksize < PAGE_SIZE in fscrypt_zeroout_range()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Adjust fscrypt_zeroout_range() to encrypt a block at a time rather than
a page at a time, so that it works when blocksize < PAGE_SIZE.

This isn't optimized for performance, but then again this function
already wasn't optimized for performance.  As a future optimization, we
could submit much larger bios here.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

This is based on work by Chandan Rajendra.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/bio.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index 92b2d5da5d8e1..f9111ffa12ffd 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -72,12 +72,12 @@ EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio);
 int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 				sector_t pblk, unsigned int len)
 {
+	const unsigned int blockbits = inode->i_blkbits;
+	const unsigned int blocksize = 1 << blockbits;
 	struct page *ciphertext_page;
 	struct bio *bio;
 	int ret, err = 0;
 
-	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
-
 	ciphertext_page = fscrypt_alloc_bounce_page(GFP_NOWAIT);
 	if (!ciphertext_page)
 		return -ENOMEM;
@@ -85,7 +85,7 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 	while (len--) {
 		err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,
 					  ZERO_PAGE(0), ciphertext_page,
-					  PAGE_SIZE, 0, GFP_NOFS);
+					  blocksize, 0, GFP_NOFS);
 		if (err)
 			goto errout;
 
@@ -95,14 +95,11 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 			goto errout;
 		}
 		bio_set_dev(bio, inode->i_sb->s_bdev);
-		bio->bi_iter.bi_sector =
-			pblk << (inode->i_sb->s_blocksize_bits - 9);
+		bio->bi_iter.bi_sector = pblk << (blockbits - 9);
 		bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
-		ret = bio_add_page(bio, ciphertext_page,
-					inode->i_sb->s_blocksize, 0);
-		if (ret != inode->i_sb->s_blocksize) {
+		ret = bio_add_page(bio, ciphertext_page, blocksize, 0);
+		if (WARN_ON(ret != blocksize)) {
 			/* should never happen! */
-			WARN_ON(1);
 			bio_put(bio);
 			err = -EIO;
 			goto errout;
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 08/14] fscrypt: introduce fscrypt_decrypt_block_inplace()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Currently fscrypt_decrypt_page() does one of two logically distinct
things depending on whether FS_CFLG_OWN_PAGES is set in the filesystem's
fscrypt_operations: decrypt a pagecache page in-place, or decrypt a
filesystem block in-place in any page.  Currently these happen to share
the same implementation, but this conflates the notion of blocks and
pages.  It also makes it so that all callers have to provide inode and
lblk_num, when fscrypt could determine these itself for pagecache pages.

Therefore, move the FS_CFLG_OWN_PAGES behavior into a new function
fscrypt_decrypt_block_inplace().  This mirrors
fscrypt_encrypt_block_inplace().

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/crypto.c      | 31 +++++++++++++++++++++++++++----
 fs/ubifs/crypto.c       |  7 ++++---
 include/linux/fscrypt.h | 11 +++++++++++
 3 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 7bdb985126d97..2e6fb5e4f7a7f 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -284,8 +284,7 @@ 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 in case
- *             it is a writeback page (FS_CFLG_OWN_PAGES unset).
+ * @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.
@@ -299,8 +298,7 @@ EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
 int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
 			unsigned int len, unsigned int offs, u64 lblk_num)
 {
-	if (WARN_ON_ONCE(!PageLocked(page) &&
-			 !(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES)))
+	if (WARN_ON_ONCE(!PageLocked(page)))
 		return -EINVAL;
 
 	return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
@@ -308,6 +306,31 @@ int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
 }
 EXPORT_SYMBOL(fscrypt_decrypt_page);
 
+/**
+ * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place
+ * @inode:     The inode to which this block belongs
+ * @page:      The page containing the block to decrypt
+ * @len:       Size of block to decrypt.  Doesn't need to be a multiple of the
+ *		fs block size, but must be a multiple of FS_CRYPTO_BLOCK_SIZE.
+ * @offs:      Byte offset within @page at which the block to decrypt begins
+ * @lblk_num:  Filesystem logical block number of the block, i.e. the 0-based
+ *		number of the block within the file
+ *
+ * Decrypt a possibly-compressed filesystem block that is located in an
+ * arbitrary page, not necessarily in the original pagecache page.  The @inode
+ * and @lblk_num must be specified, as they can't be determined from @page.
+ *
+ * Return: 0 on success; -errno on failure
+ */
+int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
+				  unsigned int len, unsigned int offs,
+				  u64 lblk_num)
+{
+	return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
+				   len, offs, GFP_NOFS);
+}
+EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
+
 /*
  * Validate dentries in encrypted directories to make sure we aren't potentially
  * caching stale dentries after a key has been added.
diff --git a/fs/ubifs/crypto.c b/fs/ubifs/crypto.c
index 032efdad2e668..22be7aeb96c4f 100644
--- a/fs/ubifs/crypto.c
+++ b/fs/ubifs/crypto.c
@@ -64,10 +64,11 @@ int ubifs_decrypt(const struct inode *inode, struct ubifs_data_node *dn,
 	}
 
 	ubifs_assert(c, dlen <= UBIFS_BLOCK_SIZE);
-	err = fscrypt_decrypt_page(inode, virt_to_page(&dn->data), dlen,
-			offset_in_page(&dn->data), block);
+	err = fscrypt_decrypt_block_inplace(inode, virt_to_page(&dn->data),
+					    dlen, offset_in_page(&dn->data),
+					    block);
 	if (err) {
-		ubifs_err(c, "fscrypt_decrypt_page failed: %i", err);
+		ubifs_err(c, "fscrypt_decrypt_block_inplace() failed: %d", err);
 		return err;
 	}
 	*out_len = clen;
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index c7e16bd16a6c2..315affc99b050 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -114,6 +114,9 @@ extern int fscrypt_encrypt_block_inplace(const struct inode *inode,
 					 gfp_t gfp_flags);
 extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
 				unsigned int, u64);
+extern int fscrypt_decrypt_block_inplace(const struct inode *inode,
+					 struct page *page, unsigned int len,
+					 unsigned int offs, u64 lblk_num);
 
 static inline bool fscrypt_is_bounce_page(struct page *page)
 {
@@ -315,6 +318,14 @@ static inline int fscrypt_decrypt_page(const struct inode *inode,
 	return -EOPNOTSUPP;
 }
 
+static inline int fscrypt_decrypt_block_inplace(const struct inode *inode,
+						struct page *page,
+						unsigned int len,
+						unsigned int offs, u64 lblk_num)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline bool fscrypt_is_bounce_page(struct page *page)
 {
 	return false;
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 09/14] fscrypt: support decrypting multiple filesystem blocks per page

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Rename fscrypt_decrypt_page() to fscrypt_decrypt_pagecache_blocks() and
redefine its behavior to decrypt all filesystem blocks in the given
region of the given page, rather than assuming that the region consists
of just one filesystem block.  Also remove the 'inode' and 'lblk_num'
parameters, since they can be retrieved from the page as it's already
assumed to be a pagecache page.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

This is based on work by Chandan Rajendra.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/bio.c         |  3 +--
 fs/crypto/crypto.c      | 46 ++++++++++++++++++++++++++++-------------
 fs/ext4/inode.c         |  7 +++----
 include/linux/fscrypt.h | 12 +++++------
 4 files changed, 42 insertions(+), 26 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index f9111ffa12ffd..61da06fda45cc 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 2e6fb5e4f7a7f..dcf630d7e4460 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -282,29 +282,47 @@ 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 82298c63ea6d6..34fda4864c0eb 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 315affc99b050..bd8f207a2fb68 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;
 }
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 10/14] fscrypt: decrypt only the needed blocks in __fscrypt_decrypt_bio()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

In __fscrypt_decrypt_bio(), only decrypt the blocks that actually
comprise the bio, rather than assuming blocksize == PAGE_SIZE and
decrypting the entirety of every page used in the bio.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

This is based on work by Chandan Rajendra.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/bio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index 61da06fda45cc..82da2510721f6 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -33,8 +33,8 @@ 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_pagecache_blocks(page, PAGE_SIZE, 0);
-
+		int ret = fscrypt_decrypt_pagecache_blocks(page, bv->bv_len,
+							   bv->bv_offset);
 		if (ret)
 			SetPageError(page);
 		else if (done)
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 11/14] ext4: clear BH_Uptodate flag on decryption error

[Eric Biggers]

From: Chandan Rajendra <chandan@linux.ibm.com>

If decryption fails, ext4_block_write_begin() can return with the page's
buffer_head marked with the BH_Uptodate flag.  This commit clears the
BH_Uptodate flag in such cases.

Signed-off-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/ext4/inode.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 34fda4864c0eb..0e6536a22a465 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1229,10 +1229,14 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 		if (!buffer_uptodate(*wait_bh))
 			err = -EIO;
 	}
-	if (unlikely(err))
+	if (unlikely(err)) {
 		page_zero_new_buffers(page, from, to);
-	else if (decrypt)
+	} else if (decrypt) {
 		err = fscrypt_decrypt_pagecache_blocks(page, PAGE_SIZE, 0);
+		if (err)
+			clear_buffer_uptodate(*wait_bh);
+	}
+
 	return err;
 }
 #endif
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 12/14] ext4: decrypt only the needed blocks in ext4_block_write_begin()

[Eric Biggers]

From: Chandan Rajendra <chandan@linux.ibm.com>

In ext4_block_write_begin(), only decrypt the blocks that actually need
to be decrypted (up to two blocks which intersect the boundaries of the
region that will be written to), rather than assuming blocksize ==
PAGE_SIZE and decrypting the whole page.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

Signed-off-by: Chandan Rajendra <chandan@linux.ibm.com>
(EB: rebase onto previous changes, improve the commit message,
 and move the check for encrypted inode)
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/ext4/inode.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0e6536a22a465..8b3ea9c8ac988 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1164,8 +1164,9 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 	int err = 0;
 	unsigned blocksize = inode->i_sb->s_blocksize;
 	unsigned bbits;
-	struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
-	bool decrypt = false;
+	struct buffer_head *bh, *head, *wait[2];
+	int nr_wait = 0;
+	int i;
 
 	BUG_ON(!PageLocked(page));
 	BUG_ON(from > PAGE_SIZE);
@@ -1217,24 +1218,30 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 		    !buffer_unwritten(bh) &&
 		    (block_start < from || block_end > to)) {
 			ll_rw_block(REQ_OP_READ, 0, 1, &bh);
-			*wait_bh++ = bh;
-			decrypt = IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
+			wait[nr_wait++] = bh;
 		}
 	}
 	/*
 	 * If we issued read requests, let them complete.
 	 */
-	while (wait_bh > wait) {
-		wait_on_buffer(*--wait_bh);
-		if (!buffer_uptodate(*wait_bh))
+	for (i = 0; i < nr_wait; i++) {
+		wait_on_buffer(wait[i]);
+		if (!buffer_uptodate(wait[i]))
 			err = -EIO;
 	}
 	if (unlikely(err)) {
 		page_zero_new_buffers(page, from, to);
-	} else if (decrypt) {
-		err = fscrypt_decrypt_pagecache_blocks(page, PAGE_SIZE, 0);
-		if (err)
-			clear_buffer_uptodate(*wait_bh);
+	} else if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode)) {
+		for (i = 0; i < nr_wait; i++) {
+			int err2;
+
+			err2 = fscrypt_decrypt_pagecache_blocks(page, blocksize,
+								bh_offset(wait[i]));
+			if (err2) {
+				clear_buffer_uptodate(wait[i]);
+				err = err2;
+			}
+		}
 	}
 
 	return err;
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 13/14] ext4: decrypt only the needed block in __ext4_block_zero_page_range()

[Eric Biggers]

From: Chandan Rajendra <chandan@linux.ibm.com>

In __ext4_block_zero_page_range(), only decrypt the block that actually
needs to be decrypted, rather than assuming blocksize == PAGE_SIZE and
decrypting the whole page.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

Signed-off-by: Chandan Rajendra <chandan@linux.ibm.com>
(EB: rebase onto previous changes, improve the commit message, and use
 bh_offset())
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/ext4/inode.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8b3ea9c8ac988..77c43c50e4580 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4075,9 +4075,8 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 		if (S_ISREG(inode->i_mode) && IS_ENCRYPTED(inode)) {
 			/* We expect the key to be set. */
 			BUG_ON(!fscrypt_has_encryption_key(inode));
-			BUG_ON(blocksize != PAGE_SIZE);
 			WARN_ON_ONCE(fscrypt_decrypt_pagecache_blocks(
-						page, PAGE_SIZE, 0));
+					page, blocksize, bh_offset(bh)));
 		}
 	}
 	if (ext4_should_journal_data(inode)) {
-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH v2 14/14] ext4: encrypt only up to last block in ext4_bio_write_page()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

As an optimization, don't encrypt blocks fully beyond i_size, since
those definitely won't need to be written out.  Also add a comment.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

This is based on work by Chandan Rajendra.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/ext4/page-io.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 40ee33df57649..a18a47a2a1d1a 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -467,11 +467,19 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 
 	bh = head = page_buffers(page);
 
+	/*
+	 * If any blocks are being written to an encrypted file, encrypt them
+	 * into a bounce page.  For simplicity, just encrypt until the last
+	 * block which might be needed.  This may cause some unneeded blocks
+	 * (e.g. holes) to be unnecessarily encrypted, but this is rare and
+	 * can't happen in the common case of blocksize == PAGE_SIZE.
+	 */
 	if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode) && nr_to_submit) {
 		gfp_t gfp_flags = GFP_NOFS;
+		unsigned int enc_bytes = round_up(len, i_blocksize(inode));
 
 	retry_encrypt:
-		bounce_page = fscrypt_encrypt_pagecache_blocks(page, PAGE_SIZE,
+		bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes,
 							       0, gfp_flags);
 		if (IS_ERR(bounce_page)) {
 			ret = PTR_ERR(bounce_page);
-- 
2.21.0.1020.gf2820cf01a-goog

Re: [PATCH v2 00/14] fscrypt, ext4: prepare for blocksize != PAGE_SIZE

[Eric Biggers]

On Mon, May 20, 2019 at 09:29:38AM -0700, Eric Biggers wrote:
> Hello,
> 
> This patchset prepares fs/crypto/, and partially ext4, for the
> 'blocksize != PAGE_SIZE' case.
> 
> This basically contains the encryption changes from Chandan Rajendra's
> patchset "[V2,00/13] Consolidate FS read I/O callbacks code"
> (https://patchwork.kernel.org/project/linux-fscrypt/list/?series=111039)
> that don't require introducing the read_callbacks and don't depend on
> fsverity stuff.  But they've been reworked to clean things up a lot.
> 
> I'd like to apply this patchset for 5.3 in order to make things forward
> for ext4 encryption with 'blocksize != PAGE_SIZE'.
> 
> AFAICT, after this patchset the only thing stopping ext4 encryption from
> working with blocksize != PAGE_SIZE is the lack of encryption support in
> block_read_full_page(), which the read_callbacks will address.
> 
> This patchset applies to v5.2-rc1, and it can also be retrieved from git
> at https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git
> branch "fscrypt-subpage-blocks-prep".
> 
> Changed since v1 (minor cleanups only):
> 
> - In "fscrypt: simplify bounce page handling", also remove
>   the definition of FS_CTX_HAS_BOUNCE_BUFFER_FL.
> 
> - In "ext4: decrypt only the needed blocks in ext4_block_write_begin()",
>   simplify the code slightly by moving the IS_ENCRYPTED() check.
> 
> - Change __fscrypt_decrypt_bio() in a separate patch rather than as part
>   of "fscrypt: support decrypting multiple filesystem blocks per page".
>   The resulting code is the same, so I kept Chandan's Reviewed-by.
> 
> - Improve the commit message of
>   "fscrypt: introduce fscrypt_decrypt_block_inplace()".
> 
> Chandan Rajendra (3):
>   ext4: clear BH_Uptodate flag on decryption error
>   ext4: decrypt only the needed blocks in ext4_block_write_begin()
>   ext4: decrypt only the needed block in __ext4_block_zero_page_range()
> 
> Eric Biggers (11):
>   fscrypt: simplify bounce page handling
>   fscrypt: remove the "write" part of struct fscrypt_ctx
>   fscrypt: rename fscrypt_do_page_crypto() to fscrypt_crypt_block()
>   fscrypt: clean up some BUG_ON()s in block encryption/decryption
>   fscrypt: introduce fscrypt_encrypt_block_inplace()
>   fscrypt: support encrypting multiple filesystem blocks per page
>   fscrypt: handle blocksize < PAGE_SIZE in fscrypt_zeroout_range()
>   fscrypt: introduce fscrypt_decrypt_block_inplace()
>   fscrypt: support decrypting multiple filesystem blocks per page
>   fscrypt: decrypt only the needed blocks in __fscrypt_decrypt_bio()
>   ext4: encrypt only up to last block in ext4_bio_write_page()
> 
>  fs/crypto/bio.c             |  73 +++------
>  fs/crypto/crypto.c          | 299 ++++++++++++++++++++----------------
>  fs/crypto/fscrypt_private.h |  15 +-
>  fs/ext4/inode.c             |  37 +++--
>  fs/ext4/page-io.c           |  44 +++---
>  fs/f2fs/data.c              |  17 +-
>  fs/ubifs/crypto.c           |  19 +--
>  include/linux/fscrypt.h     |  96 ++++++++----
>  8 files changed, 319 insertions(+), 281 deletions(-)
> 

I've applied this series to fscrypt.git for 5.3.

- Eric