[PATCH 13/16] fscrypt: Remove fs-layer zeroout code

[Eric Biggers <ebiggers@kernel.org>]

Now that fscrypt's file contents en/decryption is always implemented
using blk-crypto when the filesystem is block-based, the fs-layer
zeroout code in fs/crypto/bio.c is unused code.  Remove it, then fold
fscrypt_zeroout_range_inline_crypt() into fscrypt_zeroout_range().

Then make fscrypt_alloc_bounce_page() and fscrypt_crypt_data_unit()
static, since they're no longer called from any other file.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 fs/crypto/bio.c             | 134 +++++++-----------------------------
 fs/crypto/crypto.c          |  14 ++--
 fs/crypto/fscrypt_private.h |   5 --
 3 files changed, 32 insertions(+), 121 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index d07740680602..58b6b13eeedd 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -67,20 +67,40 @@ static void fscrypt_zeroout_range_end_io(struct bio *bio)
 		cmpxchg(&done->status, 0, bio->bi_status);
 	fscrypt_zeroout_range_done(done);
 	bio_put(bio);
 }
 
-static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,
-					      loff_t pos, sector_t sector,
-					      u64 len)
+/**
+ * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file
+ * @inode: the file's inode
+ * @pos: the first file position (in bytes) to zero out
+ * @sector: the first sector to zero out
+ * @len: bytes to zero out
+ *
+ * Zero out filesystem blocks in an encrypted regular file on-disk, i.e. write
+ * ciphertext blocks which decrypt to the all-zeroes block.  The blocks must be
+ * both logically and physically contiguous.  It's also assumed that the
+ * filesystem only uses a single block device, ->s_bdev.  @len must be a
+ * multiple of the file system logical block size.
+ *
+ * Note that since each block uses a different IV, this involves writing a
+ * different ciphertext to each block; we can't simply reuse the same one.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int fscrypt_zeroout_range(const struct inode *inode, loff_t pos,
+			  sector_t sector, u64 len)
 {
 	struct fscrypt_zero_done done = {
 		.pending	= ATOMIC_INIT(1),
 		.done		= COMPLETION_INITIALIZER_ONSTACK(done.done),
 	};
 
-	while (len) {
+	if (len == 0)
+		return 0;
+
+	do {
 		struct bio *bio;
 		unsigned int n;
 
 		bio = bio_alloc(inode->i_sb->s_bdev, BIO_MAX_VECS, REQ_OP_WRITE,
 				GFP_NOFS);
@@ -100,117 +120,13 @@ static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,
 				break;
 		}
 
 		atomic_inc(&done.pending);
 		blk_crypto_submit_bio(bio);
-	}
+	} while (len);
 
 	fscrypt_zeroout_range_done(&done);
 
 	wait_for_completion(&done.done);
 	return blk_status_to_errno(done.status);
 }
-
-/**
- * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file
- * @inode: the file's inode
- * @pos: the first file position (in bytes) to zero out
- * @sector: the first sector to zero out
- * @len: bytes to zero out
- *
- * Zero out filesystem blocks in an encrypted regular file on-disk, i.e. write
- * ciphertext blocks which decrypt to the all-zeroes block.  The blocks must be
- * both logically and physically contiguous.  It's also assumed that the
- * filesystem only uses a single block device, ->s_bdev.  @len must be a
- * multiple of the file system logical block size.
- *
- * Note that since each block uses a different IV, this involves writing a
- * different ciphertext to each block; we can't simply reuse the same one.
- *
- * Return: 0 on success; -errno on failure.
- */
-int fscrypt_zeroout_range(const struct inode *inode, loff_t pos,
-			  sector_t sector, u64 len)
-{
-	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
-	const unsigned int du_bits = ci->ci_data_unit_bits;
-	const unsigned int du_size = 1U << du_bits;
-	const unsigned int du_per_page_bits = PAGE_SHIFT - du_bits;
-	const unsigned int du_per_page = 1U << du_per_page_bits;
-	u64 du_index = pos >> du_bits;
-	u64 du_remaining = len >> du_bits;
-	struct page *pages[16]; /* write up to 16 pages at a time */
-	unsigned int nr_pages;
-	unsigned int i;
-	unsigned int offset;
-	struct bio *bio;
-	int ret, err;
-
-	if (len == 0)
-		return 0;
-
-	if (fscrypt_inode_uses_inline_crypto(inode))
-		return fscrypt_zeroout_range_inline_crypt(inode, pos, sector,
-							  len);
-
-	BUILD_BUG_ON(ARRAY_SIZE(pages) > BIO_MAX_VECS);
-	nr_pages = min_t(u64, ARRAY_SIZE(pages),
-			 (du_remaining + du_per_page - 1) >> du_per_page_bits);
-
-	/*
-	 * We need at least one page for ciphertext.  Allocate the first one
-	 * from a mempool, with __GFP_DIRECT_RECLAIM set so that it can't fail.
-	 *
-	 * Any additional page allocations are allowed to fail, as they only
-	 * help performance, and waiting on the mempool for them could deadlock.
-	 */
-	for (i = 0; i < nr_pages; i++) {
-		pages[i] = fscrypt_alloc_bounce_page(i == 0 ? GFP_NOFS :
-						     GFP_NOWAIT);
-		if (!pages[i])
-			break;
-	}
-	nr_pages = i;
-	if (WARN_ON_ONCE(nr_pages <= 0))
-		return -EINVAL;
-
-	/* This always succeeds since __GFP_DIRECT_RECLAIM is set. */
-	bio = bio_alloc(inode->i_sb->s_bdev, nr_pages, REQ_OP_WRITE, GFP_NOFS);
-
-	do {
-		bio->bi_iter.bi_sector = sector;
-
-		i = 0;
-		offset = 0;
-		do {
-			err = fscrypt_crypt_data_unit(ci, FS_ENCRYPT, du_index,
-						      ZERO_PAGE(0), pages[i],
-						      du_size, offset);
-			if (err)
-				goto out;
-			du_index++;
-			sector += 1U << (du_bits - SECTOR_SHIFT);
-			du_remaining--;
-			offset += du_size;
-			if (offset == PAGE_SIZE || du_remaining == 0) {
-				ret = bio_add_page(bio, pages[i++], offset, 0);
-				if (WARN_ON_ONCE(ret != offset)) {
-					err = -EIO;
-					goto out;
-				}
-				offset = 0;
-			}
-		} while (i != nr_pages && du_remaining != 0);
-
-		err = submit_bio_wait(bio);
-		if (err)
-			goto out;
-		bio_reset(bio, inode->i_sb->s_bdev, REQ_OP_WRITE);
-	} while (du_remaining != 0);
-	err = 0;
-out:
-	bio_put(bio);
-	for (i = 0; i < nr_pages; i++)
-		fscrypt_free_bounce_page(pages[i]);
-	return err;
-}
 EXPORT_SYMBOL(fscrypt_zeroout_range);
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 94dd6c89ddcd..8c4660429418 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -47,11 +47,11 @@ void fscrypt_enqueue_decrypt_work(struct work_struct *work)
 {
 	queue_work(fscrypt_read_workqueue, work);
 }
 EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
 
-struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
+static struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
 {
 	if (WARN_ON_ONCE(!fscrypt_bounce_page_pool)) {
 		/*
 		 * Oops, the filesystem called a function that uses the bounce
 		 * page pool, but it didn't set needs_bounce_pages.
@@ -63,12 +63,11 @@ struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
 
 /**
  * fscrypt_free_bounce_page() - free a ciphertext bounce page
  * @bounce_page: the bounce page to free, or NULL
  *
- * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks(),
- * or by fscrypt_alloc_bounce_page() directly.
+ * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks().
  */
 void fscrypt_free_bounce_page(struct page *bounce_page)
 {
 	if (!bounce_page)
 		return;
@@ -105,14 +104,15 @@ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 index,
 	}
 	iv->index = cpu_to_le64(index);
 }
 
 /* Encrypt or decrypt a single "data unit" of file contents. */
-int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci,
-			    fscrypt_direction_t rw, u64 index,
-			    struct page *src_page, struct page *dest_page,
-			    unsigned int len, unsigned int offs)
+static int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci,
+				   fscrypt_direction_t rw, u64 index,
+				   struct page *src_page,
+				   struct page *dest_page, unsigned int len,
+				   unsigned int offs)
 {
 	struct crypto_sync_skcipher *tfm = ci->ci_enc_key.tfm;
 	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
 	union fscrypt_iv iv;
 	struct scatterlist dst, src;
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 57b7ae2cfafc..da9040407d4a 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -327,15 +327,10 @@ typedef enum {
 } fscrypt_direction_t;
 
 /* crypto.c */
 extern struct kmem_cache *fscrypt_inode_info_cachep;
 int fscrypt_initialize(struct super_block *sb);
-int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci,
-			    fscrypt_direction_t rw, u64 index,
-			    struct page *src_page, struct page *dest_page,
-			    unsigned int len, unsigned int offs);
-struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
 
 void __printf(3, 4) __cold
 fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
 
 #define fscrypt_warn(inode, fmt, ...)		\
-- 
2.54.0