[RFC,V2,07/11] fscrypt_zeroout_range: Encrypt all zeroed out blocks of a page

Message ID 20180212094347.22071-8-chandan@linux.vnet.ibm.com
State New
Headers show
Series
  • Ext4 encryption support for blocksize < pagesize
Related show

Commit Message

Chandan Rajendra Feb. 12, 2018, 9:43 a.m.
For block size < page size, This commit adds code to encrypt all zeroed
out blocks of a page.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
---
 fs/crypto/bio.c | 38 +++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 13 deletions(-)

Comments

Eric Biggers Feb. 21, 2018, 1:16 a.m. | #1
On Mon, Feb 12, 2018 at 03:13:43PM +0530, Chandan Rajendra wrote:
> For block size < page size, This commit adds code to encrypt all zeroed
> out blocks of a page.
> 
> Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
> ---
>  fs/crypto/bio.c | 38 +++++++++++++++++++++++++-------------
>  1 file changed, 25 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
> index 378df08..4d0d14f 100644
> --- a/fs/crypto/bio.c
> +++ b/fs/crypto/bio.c
> @@ -104,10 +104,12 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
>  {
>  	struct fscrypt_ctx *ctx;
>  	struct page *ciphertext_page = NULL;
> +	unsigned int page_nr_blks;
> +	unsigned int offset;
> +	unsigned int page_io_len;
>  	struct bio *bio;
>  	int ret, err = 0;
> -
> -	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
> +	int i;
>  
>  	ctx = fscrypt_get_ctx(inode, GFP_NOFS);
>  	if (IS_ERR(ctx))
> @@ -119,12 +121,23 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
>  		goto errout;
>  	}
>  
> -	while (len--) {
> -		err = fscrypt_do_block_crypto(inode, FS_ENCRYPT, lblk,
> -					     ZERO_PAGE(0), ciphertext_page,
> -					     PAGE_SIZE, 0, GFP_NOFS);
> -		if (err)
> -			goto errout;
> +	page_nr_blks = 1 << (PAGE_SHIFT - inode->i_blkbits);
> +
> +	while (len) {
> +		page_nr_blks = min_t(unsigned int, page_nr_blks, len);
> +		page_io_len = page_nr_blks << inode->i_blkbits;
> +		offset = 0;

The 'page_io_len' variable isn't needed, since 'offset == page_io_len' after the
encryption loop.  You can do 'bio_add_page(bio, ciphertext_page, offset, 0);'.

Eric
Chandan Rajendra Feb. 21, 2018, 9:57 a.m. | #2
On Wednesday, February 21, 2018 6:46:48 AM IST Eric Biggers wrote:
> On Mon, Feb 12, 2018 at 03:13:43PM +0530, Chandan Rajendra wrote:
> > For block size < page size, This commit adds code to encrypt all zeroed
> > out blocks of a page.
> > 
> > Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
> > ---
> >  fs/crypto/bio.c | 38 +++++++++++++++++++++++++-------------
> >  1 file changed, 25 insertions(+), 13 deletions(-)
> > 
> > diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
> > index 378df08..4d0d14f 100644
> > --- a/fs/crypto/bio.c
> > +++ b/fs/crypto/bio.c
> > @@ -104,10 +104,12 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
> >  {
> >  	struct fscrypt_ctx *ctx;
> >  	struct page *ciphertext_page = NULL;
> > +	unsigned int page_nr_blks;
> > +	unsigned int offset;
> > +	unsigned int page_io_len;
> >  	struct bio *bio;
> >  	int ret, err = 0;
> > -
> > -	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
> > +	int i;
> >  
> >  	ctx = fscrypt_get_ctx(inode, GFP_NOFS);
> >  	if (IS_ERR(ctx))
> > @@ -119,12 +121,23 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
> >  		goto errout;
> >  	}
> >  
> > -	while (len--) {
> > -		err = fscrypt_do_block_crypto(inode, FS_ENCRYPT, lblk,
> > -					     ZERO_PAGE(0), ciphertext_page,
> > -					     PAGE_SIZE, 0, GFP_NOFS);
> > -		if (err)
> > -			goto errout;
> > +	page_nr_blks = 1 << (PAGE_SHIFT - inode->i_blkbits);
> > +
> > +	while (len) {
> > +		page_nr_blks = min_t(unsigned int, page_nr_blks, len);
> > +		page_io_len = page_nr_blks << inode->i_blkbits;
> > +		offset = 0;
> 
> The 'page_io_len' variable isn't needed, since 'offset == page_io_len' after the
> encryption loop.  You can do 'bio_add_page(bio, ciphertext_page, offset, 0);'.
> 

You are right. I will fix that up in the next iteration of the patchset.

Patch

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index 378df08..4d0d14f 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -104,10 +104,12 @@  int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 {
 	struct fscrypt_ctx *ctx;
 	struct page *ciphertext_page = NULL;
+	unsigned int page_nr_blks;
+	unsigned int offset;
+	unsigned int page_io_len;
 	struct bio *bio;
 	int ret, err = 0;
-
-	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
+	int i;
 
 	ctx = fscrypt_get_ctx(inode, GFP_NOFS);
 	if (IS_ERR(ctx))
@@ -119,12 +121,23 @@  int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 		goto errout;
 	}
 
-	while (len--) {
-		err = fscrypt_do_block_crypto(inode, FS_ENCRYPT, lblk,
-					     ZERO_PAGE(0), ciphertext_page,
-					     PAGE_SIZE, 0, GFP_NOFS);
-		if (err)
-			goto errout;
+	page_nr_blks = 1 << (PAGE_SHIFT - inode->i_blkbits);
+
+	while (len) {
+		page_nr_blks = min_t(unsigned int, page_nr_blks, len);
+		page_io_len = page_nr_blks << inode->i_blkbits;
+		offset = 0;
+
+		for (i = 0; i < page_nr_blks; i++) {
+			err = fscrypt_do_block_crypto(inode, FS_ENCRYPT, lblk,
+						ZERO_PAGE(0), ciphertext_page,
+						inode->i_sb->s_blocksize, offset,
+						GFP_NOFS);
+			if (err)
+				goto errout;
+			lblk++;
+			offset += inode->i_sb->s_blocksize;
+		}
 
 		bio = bio_alloc(GFP_NOWAIT, 1);
 		if (!bio) {
@@ -135,9 +148,8 @@  int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 		bio->bi_iter.bi_sector =
 			pblk << (inode->i_sb->s_blocksize_bits - 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, page_io_len, 0);
+		if (ret != page_io_len) {
 			/* should never happen! */
 			WARN_ON(1);
 			bio_put(bio);
@@ -150,8 +162,8 @@  int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 		bio_put(bio);
 		if (err)
 			goto errout;
-		lblk++;
-		pblk++;
+		pblk += page_nr_blks;
+		len -= page_nr_blks;
 	}
 	err = 0;
 errout: