Hi Eric,
On 2018/4/18 1:42, Eric Biggers wrote:
> Hi Chao,
>
> On Tue, Apr 17, 2018 at 05:13:12PM +0800, Chao Yu wrote:
>>> +
>>> +static void bio_post_read_processing(struct bio_post_read_ctx *ctx);
>>> +
>>> +static void decrypt_work(struct work_struct *work)
>>> +{
>>> + struct bio_post_read_ctx *ctx =
>>> + container_of(work, struct bio_post_read_ctx, work);
>>> +
>>> + fscrypt_decrypt_bio(ctx->bio);
>>> +
>>> + bio_post_read_processing(ctx);
>>> +}
>>> +
>>> +static void bio_post_read_processing(struct bio_post_read_ctx *ctx)
>>> +{
>>> + switch (++ctx->cur_step) {
>>> + case STEP_DECRYPT:
>>> + if (ctx->enabled_steps & (1 << STEP_DECRYPT)) {
>>> + INIT_WORK(&ctx->work, decrypt_work);
>>> + fscrypt_enqueue_decrypt_work(&ctx->work);
>>> + return;
>>> + }
>>> + ctx->cur_step++;
>>> + /* fall-through */
>>> + default:
>>> + __read_end_io(ctx->bio);
>>> + }
>>
>> How about introducing __bio_post_read_processing()
>>
>> switch (step) {
>> case STEP_DECRYPT:
>> ...
>> break;
>> case STEP_COMPRESS:
>> ...
>> break;
>> case STEP_GENERIC:
>> __read_end_io;
>> break;
>> ...
>> }
>>
>> Then we can customize flexible read processes like:
>>
>> bio_post_read_processing()
>> {
>> if (encrypt_enabled)
>> __bio_post_read_processing(, STEP_DECRYPT);
>> if (compress_enabled)
>> __bio_post_read_processing(, STEP_COMPRESS);
>> __bio_post_read_processing(, STEP_GENERIC);
>> }
>>
>> Or other flow.
>
> If I understand correctly, you're suggesting that all the steps be done in a
> single workqueue item? The problem with that is that the verity work will
Yup,
> require I/O to the file to read hashes, which may need STEP_DECRYPT. Hence,
> decryption and verity will need separate workqueues.
For decryption and verity, the needs separated data, I agree that we can not
merge the work into one workqueue.
As you mentioned in commit message, it can be used by compression later, so I
just thought that for decryption and decompression, maybe we can do those work
sequentially in one workqueue?
>
>>> @@ -481,29 +537,33 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
>>> unsigned nr_pages)
>>> {
>>> struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>> - struct fscrypt_ctx *ctx = NULL;
>>> struct bio *bio;
>>> -
>>> - if (f2fs_encrypted_file(inode)) {
>>> - ctx = fscrypt_get_ctx(inode, GFP_NOFS);
>>> - if (IS_ERR(ctx))
>>> - return ERR_CAST(ctx);
>>> -
>>> - /* wait the page to be moved by cleaning */
>>> - f2fs_wait_on_block_writeback(sbi, blkaddr);
>>> - }
>>> + struct bio_post_read_ctx *ctx;
>>> + unsigned int post_read_steps = 0;
>>>
>>> bio = f2fs_bio_alloc(sbi, min_t(int, nr_pages, BIO_MAX_PAGES), false);
>>> - if (!bio) {
>>> - if (ctx)
>>> - fscrypt_release_ctx(ctx);
>>> + if (!bio)
>>> return ERR_PTR(-ENOMEM);
>>> - }
>>> f2fs_target_device(sbi, blkaddr, bio);
>>> bio->bi_end_io = f2fs_read_end_io;
>>> - bio->bi_private = ctx;
>>
>> bio->bi_private = NULL;
>>
>
> I don't see why. ->bi_private is NULL by default.
As we will check bi_private in read_end_io anyway, if it is not NULL, we will
parse it as an ctx, am I missing something?
Thanks,
>
>>> + bio_post_read_ctx_pool =
>>> + mempool_create_slab_pool(128, bio_post_read_ctx_cache);
>>
>> #define MAX_POST_READ_CACHE_SIZE 128
>>
>
> Yes, that makes sense.
>
> - Eric
>
> .
>
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