dm crypt: don't allocate pages for a partial request
Change crypt_alloc_buffer so that it only ever allocates pages for a
full request. This is a prerequisite for the commit "dm crypt: offload
writes to thread".
This change simplifies the dm-crypt code at the expense of reduced
throughput in low memory conditions (where allocation for a partial
request is most useful).
Note: the next commit ("dm crypt: avoid deadlock in mempools") is needed
to fix a theoretical deadlock.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka
Mike Snitzer
Родитель
f3396c58fd
Коммит
cf2f1abfbd
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@ -58,7 +58,6 @@ struct dm_crypt_io {
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atomic_t io_pending;
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int error;
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sector_t sector;
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struct dm_crypt_io *base_io;
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} CRYPTO_MINALIGN_ATTR;
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struct dm_crypt_request {
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@ -172,7 +171,6 @@ struct crypt_config {
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};
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#define MIN_IOS 16
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#define MIN_POOL_PAGES 32
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static struct kmem_cache *_crypt_io_pool;
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@ -946,14 +944,13 @@ static int crypt_convert(struct crypt_config *cc,
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return 0;
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}
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static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone);
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/*
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* Generate a new unfragmented bio with the given size
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* This should never violate the device limitations
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* May return a smaller bio when running out of pages, indicated by
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* *out_of_pages set to 1.
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*/
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static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size,
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unsigned *out_of_pages)
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static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
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{
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struct crypt_config *cc = io->cc;
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struct bio *clone;
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@ -961,43 +958,29 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size,
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gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
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unsigned i, len;
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struct page *page;
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struct bio_vec *bvec;
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clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
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if (!clone)
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return NULL;
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clone_init(io, clone);
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*out_of_pages = 0;
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for (i = 0; i < nr_iovecs; i++) {
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page = mempool_alloc(cc->page_pool, gfp_mask);
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if (!page) {
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*out_of_pages = 1;
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break;
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}
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/*
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* If additional pages cannot be allocated without waiting,
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* return a partially-allocated bio. The caller will then try
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* to allocate more bios while submitting this partial bio.
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*/
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gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
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len = (size > PAGE_SIZE) ? PAGE_SIZE : size;
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if (!bio_add_page(clone, page, len, 0)) {
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mempool_free(page, cc->page_pool);
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break;
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}
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bvec = &clone->bi_io_vec[clone->bi_vcnt++];
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bvec->bv_page = page;
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bvec->bv_len = len;
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bvec->bv_offset = 0;
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clone->bi_iter.bi_size += len;
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size -= len;
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}
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if (!clone->bi_iter.bi_size) {
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bio_put(clone);
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return NULL;
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}
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return clone;
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}
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@ -1020,7 +1003,6 @@ static void crypt_io_init(struct dm_crypt_io *io, struct crypt_config *cc,
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io->base_bio = bio;
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io->sector = sector;
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io->error = 0;
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io->base_io = NULL;
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io->ctx.req = NULL;
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atomic_set(&io->io_pending, 0);
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}
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@ -1033,13 +1015,11 @@ static void crypt_inc_pending(struct dm_crypt_io *io)
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/*
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* One of the bios was finished. Check for completion of
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* the whole request and correctly clean up the buffer.
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* If base_io is set, wait for the last fragment to complete.
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*/
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static void crypt_dec_pending(struct dm_crypt_io *io)
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{
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struct crypt_config *cc = io->cc;
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struct bio *base_bio = io->base_bio;
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struct dm_crypt_io *base_io = io->base_io;
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int error = io->error;
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if (!atomic_dec_and_test(&io->io_pending))
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@ -1050,13 +1030,7 @@ static void crypt_dec_pending(struct dm_crypt_io *io)
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if (io != dm_per_bio_data(base_bio, cc->per_bio_data_size))
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mempool_free(io, cc->io_pool);
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if (likely(!base_io))
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bio_endio(base_bio, error);
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else {
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if (error && !base_io->error)
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base_io->error = error;
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crypt_dec_pending(base_io);
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}
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bio_endio(base_bio, error);
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}
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/*
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@ -1192,10 +1166,7 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
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{
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struct crypt_config *cc = io->cc;
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struct bio *clone;
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struct dm_crypt_io *new_io;
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int crypt_finished;
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unsigned out_of_pages = 0;
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unsigned remaining = io->base_bio->bi_iter.bi_size;
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sector_t sector = io->sector;
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int r;
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@ -1205,80 +1176,30 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
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crypt_inc_pending(io);
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crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector);
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/*
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* The allocated buffers can be smaller than the whole bio,
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* so repeat the whole process until all the data can be handled.
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*/
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while (remaining) {
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clone = crypt_alloc_buffer(io, remaining, &out_of_pages);
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if (unlikely(!clone)) {
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io->error = -ENOMEM;
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break;
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}
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io->ctx.bio_out = clone;
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io->ctx.iter_out = clone->bi_iter;
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remaining -= clone->bi_iter.bi_size;
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sector += bio_sectors(clone);
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crypt_inc_pending(io);
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r = crypt_convert(cc, &io->ctx);
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if (r < 0)
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io->error = -EIO;
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crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending);
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/* Encryption was already finished, submit io now */
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if (crypt_finished) {
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kcryptd_crypt_write_io_submit(io, 0);
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/*
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* If there was an error, do not try next fragments.
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* For async, error is processed in async handler.
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*/
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if (unlikely(r < 0))
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break;
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io->sector = sector;
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}
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/*
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* Out of memory -> run queues
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* But don't wait if split was due to the io size restriction
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*/
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if (unlikely(out_of_pages))
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congestion_wait(BLK_RW_ASYNC, HZ/100);
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/*
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* With async crypto it is unsafe to share the crypto context
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* between fragments, so switch to a new dm_crypt_io structure.
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*/
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if (unlikely(!crypt_finished && remaining)) {
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new_io = mempool_alloc(cc->io_pool, GFP_NOIO);
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crypt_io_init(new_io, io->cc, io->base_bio, sector);
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crypt_inc_pending(new_io);
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crypt_convert_init(cc, &new_io->ctx, NULL,
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io->base_bio, sector);
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new_io->ctx.iter_in = io->ctx.iter_in;
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/*
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* Fragments after the first use the base_io
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* pending count.
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*/
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if (!io->base_io)
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new_io->base_io = io;
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else {
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new_io->base_io = io->base_io;
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crypt_inc_pending(io->base_io);
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crypt_dec_pending(io);
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}
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io = new_io;
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}
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clone = crypt_alloc_buffer(io, io->base_bio->bi_iter.bi_size);
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if (unlikely(!clone)) {
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io->error = -EIO;
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goto dec;
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}
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io->ctx.bio_out = clone;
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io->ctx.iter_out = clone->bi_iter;
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sector += bio_sectors(clone);
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crypt_inc_pending(io);
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r = crypt_convert(cc, &io->ctx);
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if (r)
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io->error = -EIO;
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crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending);
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/* Encryption was already finished, submit io now */
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if (crypt_finished) {
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kcryptd_crypt_write_io_submit(io, 0);
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io->sector = sector;
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}
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dec:
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crypt_dec_pending(io);
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}
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@ -1746,7 +1667,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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sizeof(struct dm_crypt_request) + iv_size_padding + cc->iv_size,
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ARCH_KMALLOC_MINALIGN);
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cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
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cc->page_pool = mempool_create_page_pool(BIO_MAX_PAGES, 0);
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if (!cc->page_pool) {
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ti->error = "Cannot allocate page mempool";
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goto bad;
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