On Tuesday, April 30, 2019 10:21:15 PM IST Eric Biggers wrote:
> On Sun, Apr 28, 2019 at 10:01:20AM +0530, Chandan Rajendra wrote:
> > For subpage-sized blocks, this commit adds code to encrypt all zeroed
> > out blocks mapped by a page.
> >
> > Signed-off-by: Chandan Rajendra <chan...@linux.ibm.com>
> > ---
> > fs/crypto/bio.c | 40 ++++++++++++++++++----------------------
> > 1 file changed, 18 insertions(+), 22 deletions(-)
> >
> > diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
> > index 856f4694902d..46dd2ec50c7d 100644
> > --- a/fs/crypto/bio.c
> > +++ b/fs/crypto/bio.c
> > @@ -108,29 +108,23 @@ 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 bio *bio;
> > + u64 total_bytes, page_bytes;
>
> page_bytes should be 'unsigned int', since it's <= PAGE_SIZE.
>
> > int ret, err = 0;
> >
> > - BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
> > -
> > - ctx = fscrypt_get_ctx(inode, GFP_NOFS);
> > - if (IS_ERR(ctx))
> > - return PTR_ERR(ctx);
> > + total_bytes = len << inode->i_blkbits;
>
> Should cast len to 'u64' here, in case it's greater than UINT_MAX / blocksize.
>
> >
> > - ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT);
> > - if (IS_ERR(ciphertext_page)) {
> > - err = PTR_ERR(ciphertext_page);
> > - goto errout;
> > - }
> > + while (total_bytes) {
> > + page_bytes = min_t(u64, total_bytes, PAGE_SIZE);
> >
> > - while (len--) {
> > - err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk,
> > - ZERO_PAGE(0), ciphertext_page,
> > - PAGE_SIZE, 0, GFP_NOFS);
> > - if (err)
> > + ciphertext_page = fscrypt_encrypt_page(inode, ZERO_PAGE(0),
> > + page_bytes, 0, lblk, GFP_NOFS);
> > + if (IS_ERR(ciphertext_page)) {
> > + err = PTR_ERR(ciphertext_page);
> > + ciphertext_page = NULL;
> > goto errout;
> > + }
>
> 'ciphertext_page' is leaked after each loop iteration. Did you mean to free
> it,
> or did you mean to reuse it for subsequent iterations?
Thanks for pointing this out. I actually meant to free it. I will see if I can
reuse ciphertext_page in my next patchset rather than freeing and allocating
it each time the loop is executed.
>
> >
> > bio = bio_alloc(GFP_NOWAIT, 1);
> > if (!bio) {
> > @@ -141,9 +135,8 @@ int fscrypt_zeroout_range(const struct inode *inode,
> > pgoff_t lblk,
> > bio->bi_iter.bi_sector =
> > pblk << (inode->i_sb->s_blocksize_bits - 9);
>
> This line uses ->s_blocksize_bits, but your new code uses ->i_blkbits. AFAIK
> they'll always be the same, but please pick one or the other to use.
I will fix this.
>
> > 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_bytes, 0);
> > + if (ret != page_bytes) {
> > /* should never happen! */
> > WARN_ON(1);
> > bio_put(bio);
> > @@ -156,12 +149,15 @@ int fscrypt_zeroout_range(const struct inode *inode,
> > pgoff_t lblk,
> > bio_put(bio);
> > if (err)
> > goto errout;
> > - lblk++;
> > - pblk++;
> > +
> > + lblk += page_bytes >> inode->i_blkbits;
> > + pblk += page_bytes >> inode->i_blkbits;
> > + total_bytes -= page_bytes;
> > }
> > err = 0;
> > errout:
> > - fscrypt_release_ctx(ctx);
> > + if (!IS_ERR_OR_NULL(ciphertext_page))
> > + fscrypt_restore_control_page(ciphertext_page);
> > return err;
> > }
> > EXPORT_SYMBOL(fscrypt_zeroout_range);
>
>
--
chandan
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