by Chandan Rajendra

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Subject: [RFC PATCH V2 10/11] Enable writing encrypted files in blocksize less than pagesize setup

This commit splits the functionality of fscrypt_encrypt_block(). The
allocation of fscrypt context and cipher text page is moved to a new
function fscrypt_prep_ciphertext_page().

ext4_bio_write_page() is modified to appropriately make use of the above
two functions.

Signed-off-by: Chandan Rajendra <[email protected]>
---
fs/crypto/crypto.c | 71 +++++++++++++++++++++--------------------
fs/ext4/page-io.c | 34 +++++++++++++-------
include/linux/fscrypt_notsupp.h | 16 +++++++---
include/linux/fscrypt_supp.h | 9 ++++--
4 files changed, 75 insertions(+), 55 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 24e3796..8fb27ee 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -195,6 +195,35 @@ struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
return ctx->w.bounce_page;
}

+struct page *fscrypt_prep_ciphertext_page(struct inode *inode,
+ struct page *page,
+ gfp_t gfp_flags)
+{
+ struct page *ciphertext_page;
+ struct fscrypt_ctx *ctx;
+
+ BUG_ON(!PageLocked(page));
+
+ ctx = fscrypt_get_ctx(inode, gfp_flags);
+ if (IS_ERR(ctx))
+ return ERR_CAST(ctx);
+
+ ctx->w.control_page = page;
+
+ ciphertext_page = fscrypt_alloc_bounce_page(ctx, gfp_flags);
+ if (IS_ERR(ciphertext_page)) {
+ fscrypt_release_ctx(ctx);
+ return ERR_CAST(ciphertext_page);
+ }
+
+ SetPagePrivate(ciphertext_page);
+ set_page_private(ciphertext_page, (unsigned long)ctx);
+ lock_page(ciphertext_page);
+
+ return ciphertext_page;
+}
+EXPORT_SYMBOL(fscrypt_prep_ciphertext_page);
+
/**
* fscypt_encrypt_page() - Encrypts a page
* @inode: The inode for which the encryption should take place
@@ -226,15 +255,11 @@ struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
* Return: A page with the encrypted content on success. Else, an
* error value or NULL.
*/
-struct page *fscrypt_encrypt_block(const struct inode *inode,
- struct page *page,
- unsigned int len,
- unsigned int offs,
- u64 lblk_num, gfp_t gfp_flags)
-
+int fscrypt_encrypt_block(const struct inode *inode,
+ struct page *page, struct page *ciphertext_page,
+ unsigned int len, unsigned int offs,
+ u64 lblk_num, gfp_t gfp_flags)
{
- struct fscrypt_ctx *ctx;
- struct page *ciphertext_page = page;
int err;

BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0);
@@ -242,41 +267,17 @@ struct page *fscrypt_encrypt_block(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_block_crypto(inode, FS_ENCRYPT, lblk_num, page,
- ciphertext_page, len, offs,
- gfp_flags);
- if (err)
- return ERR_PTR(err);
-
- return ciphertext_page;
+ page, len, offs, gfp_flags);
+ return err;
}

BUG_ON(!PageLocked(page));

- ctx = fscrypt_get_ctx(inode, gfp_flags);
- if (IS_ERR(ctx))
- return (struct page *)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;
-
- ctx->w.control_page = page;
err = fscrypt_do_block_crypto(inode, FS_ENCRYPT, lblk_num,
page, ciphertext_page, len, offs,
gfp_flags);
- if (err) {
- ciphertext_page = ERR_PTR(err);
- goto errout;
- }
- SetPagePrivate(ciphertext_page);
- set_page_private(ciphertext_page, (unsigned long)ctx);
- lock_page(ciphertext_page);
- return ciphertext_page;
+ return err;

-errout:
- fscrypt_release_ctx(ctx);
- return ciphertext_page;
}
EXPORT_SYMBOL(fscrypt_encrypt_block);

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 0a4a1e7..1e869d5 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -419,9 +419,12 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
struct inode *inode = page->mapping->host;
unsigned block_start;
struct buffer_head *bh, *head;
+ u64 blk_nr;
+ gfp_t gfp_flags = GFP_NOFS;
int ret = 0;
int nr_submitted = 0;
int nr_to_submit = 0;
+ int blocksize = (1 << inode->i_blkbits);

BUG_ON(!PageLocked(page));
BUG_ON(PageWriteback(page));
@@ -475,15 +478,11 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
nr_to_submit++;
} while ((bh = bh->b_this_page) != head);

- bh = head = page_buffers(page);
-
- if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&
- nr_to_submit) {
- gfp_t gfp_flags = GFP_NOFS;
-
- retry_encrypt:
- data_page = fscrypt_encrypt_block(inode, page, PAGE_SIZE, 0,
- page->index, gfp_flags);
+ if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode)
+ && nr_to_submit) {
+ retry_prep_ciphertext_page:
+ data_page = fscrypt_prep_ciphertext_page(inode, page,
+ gfp_flags);
if (IS_ERR(data_page)) {
ret = PTR_ERR(data_page);
if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
@@ -492,17 +491,28 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
congestion_wait(BLK_RW_ASYNC, HZ/50);
}
gfp_flags |= __GFP_NOFAIL;
- goto retry_encrypt;
+ goto retry_prep_ciphertext_page;
}
data_page = NULL;
goto out;
}
}

+ blk_nr = page->index << (PAGE_SHIFT - inode->i_blkbits);
+
/* Now submit buffers to write */
+ bh = head = page_buffers(page);
do {
if (!buffer_async_write(bh))
continue;
+
+ if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
+ ret = fscrypt_encrypt_block(inode, page, data_page, blocksize,
+ bh_offset(bh), blk_nr, gfp_flags);
+ if (ret)
+ break;
+ }
+
ret = io_submit_add_bh(io, inode,
data_page ? data_page : page, bh);
if (ret) {
@@ -515,12 +525,12 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
}
nr_submitted++;
clear_buffer_dirty(bh);
- } while ((bh = bh->b_this_page) != head);
+ } while (++blk_nr, (bh = bh->b_this_page) != head);

/* Error stopped previous loop? Clean up buffers... */
if (ret) {
out:
- if (data_page)
+ if (data_page && bh == head)
fscrypt_restore_control_page(data_page);
printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
redirty_page_for_writepage(wbc, page);
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index aeb6b6d..3b0a53b 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -26,15 +26,21 @@ 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_prep_ciphertext_page(struct inode *inode,
+ struct page *page,
+ gfp_t gfp_flags)
{
return ERR_PTR(-EOPNOTSUPP);
}

+static inline int fscrypt_encrypt_block(const struct inode *inode,
+ struct page *page, struct page *ciphertext_page,
+ unsigned int len, unsigned int offs,
+ u64 lblk_num, gfp_t gfp_flags)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int fscrypt_decrypt_block(const struct inode *inode,
struct page *page,
unsigned int len, unsigned int offs,
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index b4c5231..68a5e91 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -15,9 +15,12 @@
extern struct kmem_cache *fscrypt_info_cachep;
extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
extern void fscrypt_release_ctx(struct fscrypt_ctx *);
-extern struct page *fscrypt_encrypt_block(const struct inode *, struct page *,
- unsigned int, unsigned int,
- u64, gfp_t);
+extern struct page *fscrypt_prep_ciphertext_page(struct inode *, struct page *,
+ gfp_t);
+extern int fscrypt_encrypt_block(const struct inode *inode,
+ struct page *page, struct page *ciphertext_page,
+ unsigned int len, unsigned int offs,
+ u64 lblk_num, gfp_t gfp_flags);
extern int fscrypt_decrypt_block(const struct inode *, struct page *, unsigned int,
unsigned int, u64);
extern void fscrypt_restore_control_page(struct page *);
--
2.9.5