static bool __journal_read_write()

in dm-integrity.c [1950:2101]

• 131 lines of code
• 25 McCabe index (conditional complexity)

static bool __journal_read_write(struct dm_integrity_io *dio, struct bio *bio,
				 unsigned journal_section, unsigned journal_entry)
{
	struct dm_integrity_c *ic = dio->ic;
	sector_t logical_sector;
	unsigned n_sectors;

	logical_sector = dio->range.logical_sector;
	n_sectors = dio->range.n_sectors;
	do {
		struct bio_vec bv = bio_iovec(bio);
		char *mem;

		if (unlikely(bv.bv_len >> SECTOR_SHIFT > n_sectors))
			bv.bv_len = n_sectors << SECTOR_SHIFT;
		n_sectors -= bv.bv_len >> SECTOR_SHIFT;
		bio_advance_iter(bio, &bio->bi_iter, bv.bv_len);
retry_kmap:
		mem = kmap_local_page(bv.bv_page);
		if (likely(dio->op == REQ_OP_WRITE))
			flush_dcache_page(bv.bv_page);

		do {
			struct journal_entry *je = access_journal_entry(ic, journal_section, journal_entry);

			if (unlikely(dio->op == REQ_OP_READ)) {
				struct journal_sector *js;
				char *mem_ptr;
				unsigned s;

				if (unlikely(journal_entry_is_inprogress(je))) {
					flush_dcache_page(bv.bv_page);
					kunmap_local(mem);

					__io_wait_event(ic->copy_to_journal_wait, !journal_entry_is_inprogress(je));
					goto retry_kmap;
				}
				smp_rmb();
				BUG_ON(journal_entry_get_sector(je) != logical_sector);
				js = access_journal_data(ic, journal_section, journal_entry);
				mem_ptr = mem + bv.bv_offset;
				s = 0;
				do {
					memcpy(mem_ptr, js, JOURNAL_SECTOR_DATA);
					*(commit_id_t *)(mem_ptr + JOURNAL_SECTOR_DATA) = je->last_bytes[s];
					js++;
					mem_ptr += 1 << SECTOR_SHIFT;
				} while (++s < ic->sectors_per_block);
#ifdef INTERNAL_VERIFY
				if (ic->internal_hash) {
					char checksums_onstack[max((size_t)HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];

					integrity_sector_checksum(ic, logical_sector, mem + bv.bv_offset, checksums_onstack);
					if (unlikely(memcmp(checksums_onstack, journal_entry_tag(ic, je), ic->tag_size))) {
						DMERR_LIMIT("Checksum failed when reading from journal, at sector 0x%llx",
							    logical_sector);
						dm_audit_log_bio(DM_MSG_PREFIX, "journal-checksum",
								 bio, logical_sector, 0);
					}
				}
#endif
			}

			if (!ic->internal_hash) {
				struct bio_integrity_payload *bip = bio_integrity(bio);
				unsigned tag_todo = ic->tag_size;
				char *tag_ptr = journal_entry_tag(ic, je);

				if (bip) do {
					struct bio_vec biv = bvec_iter_bvec(bip->bip_vec, bip->bip_iter);
					unsigned tag_now = min(biv.bv_len, tag_todo);
					char *tag_addr;
					BUG_ON(PageHighMem(biv.bv_page));
					tag_addr = bvec_virt(&biv);
					if (likely(dio->op == REQ_OP_WRITE))
						memcpy(tag_ptr, tag_addr, tag_now);
					else
						memcpy(tag_addr, tag_ptr, tag_now);
					bvec_iter_advance(bip->bip_vec, &bip->bip_iter, tag_now);
					tag_ptr += tag_now;
					tag_todo -= tag_now;
				} while (unlikely(tag_todo)); else {
					if (likely(dio->op == REQ_OP_WRITE))
						memset(tag_ptr, 0, tag_todo);
				}
			}

			if (likely(dio->op == REQ_OP_WRITE)) {
				struct journal_sector *js;
				unsigned s;

				js = access_journal_data(ic, journal_section, journal_entry);
				memcpy(js, mem + bv.bv_offset, ic->sectors_per_block << SECTOR_SHIFT);

				s = 0;
				do {
					je->last_bytes[s] = js[s].commit_id;
				} while (++s < ic->sectors_per_block);

				if (ic->internal_hash) {
					unsigned digest_size = crypto_shash_digestsize(ic->internal_hash);
					if (unlikely(digest_size > ic->tag_size)) {
						char checksums_onstack[HASH_MAX_DIGESTSIZE];
						integrity_sector_checksum(ic, logical_sector, (char *)js, checksums_onstack);
						memcpy(journal_entry_tag(ic, je), checksums_onstack, ic->tag_size);
					} else
						integrity_sector_checksum(ic, logical_sector, (char *)js, journal_entry_tag(ic, je));
				}

				journal_entry_set_sector(je, logical_sector);
			}
			logical_sector += ic->sectors_per_block;

			journal_entry++;
			if (unlikely(journal_entry == ic->journal_section_entries)) {
				journal_entry = 0;
				journal_section++;
				wraparound_section(ic, &journal_section);
			}

			bv.bv_offset += ic->sectors_per_block << SECTOR_SHIFT;
		} while (bv.bv_len -= ic->sectors_per_block << SECTOR_SHIFT);

		if (unlikely(dio->op == REQ_OP_READ))
			flush_dcache_page(bv.bv_page);
		kunmap_local(mem);
	} while (n_sectors);

	if (likely(dio->op == REQ_OP_WRITE)) {
		smp_mb();
		if (unlikely(waitqueue_active(&ic->copy_to_journal_wait)))
			wake_up(&ic->copy_to_journal_wait);
		if (READ_ONCE(ic->free_sectors) <= ic->free_sectors_threshold) {
			queue_work(ic->commit_wq, &ic->commit_work);
		} else {
			schedule_autocommit(ic);
		}
	} else {
		remove_range(ic, &dio->range);
	}

	if (unlikely(bio->bi_iter.bi_size)) {
		sector_t area, offset;

		dio->range.logical_sector = logical_sector;
		get_area_and_offset(ic, dio->range.logical_sector, &area, &offset);
		dio->metadata_block = get_metadata_sector_and_offset(ic, area, offset, &dio->metadata_offset);
		return true;
	}

	return false;
}