On Mon, Feb 12, 2018 at 03:13:46PM +0530, Chandan Rajendra wrote:
> 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 <chandan@xxxxxxxxxxxxxxxxxx>
Well, this patch also modifies ext4_bio_write_page() to support the blocksize <
pagesize case. The commit message makes it sound like it's just refactoring.
> 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);
I'm wondering why you didn't move the crypto stuff in ext4_bio_write_page() into
a separate function like I had suggested? It's true we don't have to encrypt
all the blocks in the page at once, but it would make the crypto stuff more
self-contained.
- Eric
