fscrypt: optimize fscrypt_zeroout_range()

}

EXPORT_SYMBOL(fscrypt_decrypt_bio);

/**

 * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file

 * @inode: the file's inode

 * @lblk: the first file logical block to zero out

 * @pblk: the first filesystem physical block to zero out

 * @len: number of blocks 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.

 *

 * 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, pgoff_t lblk,

			  sector_t pblk, unsigned int len)

{

	const unsigned int blockbits = inode->i_blkbits;

	const unsigned int blocksize = 1 << blockbits;

	struct page *ciphertext_page;

	const unsigned int blocks_per_page_bits = PAGE_SHIFT - blockbits;

	const unsigned int blocks_per_page = 1 << blocks_per_page_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 = 0;

	int ret, err;

	ciphertext_page = fscrypt_alloc_bounce_page(GFP_NOWAIT);

	if (!ciphertext_page)

		return -ENOMEM;

	if (len == 0)

		return 0;

	while (len--) {

		err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,

					  ZERO_PAGE(0), ciphertext_page,

					  blocksize, 0, GFP_NOFS);

		if (err)

			goto errout;

	BUILD_BUG_ON(ARRAY_SIZE(pages) > BIO_MAX_PAGES);

	nr_pages = min_t(unsigned int, ARRAY_SIZE(pages),

			 (len + blocks_per_page - 1) >> blocks_per_page_bits);

		bio = bio_alloc(GFP_NOWAIT, 1);

		if (!bio) {

			err = -ENOMEM;

			goto errout;

	/*

	 * 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 | __GFP_NOWARN);

		if (!pages[i])

			break;

	}

	nr_pages = i;

	if (WARN_ON(nr_pages <= 0))

		return -EINVAL;

	/* This always succeeds since __GFP_DIRECT_RECLAIM is set. */

	bio = bio_alloc(GFP_NOFS, nr_pages);

	do {

		bio_set_dev(bio, inode->i_sb->s_bdev);

		bio->bi_iter.bi_sector = pblk << (blockbits - 9);

		bio_set_op_attrs(bio, REQ_OP_WRITE, 0);

		ret = bio_add_page(bio, ciphertext_page, blocksize, 0);

		if (WARN_ON(ret != blocksize)) {

			/* should never happen! */

			bio_put(bio);

			err = -EIO;

			goto errout;

		}

		err = submit_bio_wait(bio);

		bio_put(bio);

		i = 0;

		offset = 0;

		do {

			err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,

						  ZERO_PAGE(0), pages[i],

						  blocksize, offset, GFP_NOFS);

			if (err)

			goto errout;

				goto out;

			lblk++;

			pblk++;

			len--;

			offset += blocksize;

			if (offset == PAGE_SIZE || len == 0) {

				ret = bio_add_page(bio, pages[i++], offset, 0);

				if (WARN_ON(ret != offset)) {

					err = -EIO;

					goto out;

				}

				offset = 0;

			}

		} while (i != nr_pages && len != 0);

		err = submit_bio_wait(bio);

		if (err)

			goto out;

		bio_reset(bio);

	} while (len != 0);

	err = 0;

errout:

	fscrypt_free_bounce_page(ciphertext_page);

out:

	bio_put(bio);

	for (i = 0; i < nr_pages; i++)

		fscrypt_free_bounce_page(pages[i]);

	return err;

}

EXPORT_SYMBOL(fscrypt_zeroout_range);