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From: | Vladimir Sementsov-Ogievskiy |
Subject: | Re: [PATCH v2 4/7] block/block-copy: refactor interfaces to use bytes instead of end |
Date: | Wed, 5 Feb 2020 14:36:18 +0300 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 |
29.01.2020 20:12, Andrey Shinkevich wrote:
On 27/11/2019 21:08, Vladimir Sementsov-Ogievskiy wrote:We have a lot of "chunk_end - start" invocations, let's switch to bytes/cur_bytes scheme instead. Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden> --- include/block/block-copy.h | 4 +-- block/block-copy.c | 68 ++++++++++++++++++++------------------ 2 files changed, 37 insertions(+), 35 deletions(-) diff --git a/include/block/block-copy.h b/include/block/block-copy.h index 0a161724d7..7321b3d305 100644 --- a/include/block/block-copy.h +++ b/include/block/block-copy.h @@ -19,8 +19,8 @@ #include "qemu/co-shared-resource.h"typedef struct BlockCopyInFlightReq {- int64_t start_byte; - int64_t end_byte; + int64_t start; + int64_t bytes; QLIST_ENTRY(BlockCopyInFlightReq) list; CoQueue wait_queue; /* coroutines blocked on this request */ } BlockCopyInFlightReq; diff --git a/block/block-copy.c b/block/block-copy.c index 94e7e855ef..cc273b6cb8 100644 --- a/block/block-copy.c +++ b/block/block-copy.c @@ -26,12 +26,12 @@static BlockCopyInFlightReq *block_copy_find_inflight_req(BlockCopyState *s,int64_t start, - int64_t end) + int64_t bytes) { BlockCopyInFlightReq *req;QLIST_FOREACH(req, &s->inflight_reqs, list) {- if (end > req->start_byte && start < req->end_byte) { + if (start + bytes > req->start && start < req->start + req->bytes) { return req; } } @@ -41,21 +41,21 @@ static BlockCopyInFlightReq *block_copy_find_inflight_req(BlockCopyState *s,static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s,int64_t start, - int64_t end) + int64_t bytes) { BlockCopyInFlightReq *req;- while ((req = block_copy_find_inflight_req(s, start, end))) {+ while ((req = block_copy_find_inflight_req(s, start, bytes))) { qemu_co_queue_wait(&req->wait_queue, NULL); } }static void block_copy_inflight_req_begin(BlockCopyState *s,BlockCopyInFlightReq *req, - int64_t start, int64_t end) + int64_t start, int64_t bytes) { - req->start_byte = start; - req->end_byte = end; + req->start = start; + req->bytes = bytes; qemu_co_queue_init(&req->wait_queue); QLIST_INSERT_HEAD(&s->inflight_reqs, req, list); } @@ -150,24 +150,26 @@ void block_copy_set_callbacks( /* * block_copy_do_copy * - * Do copy of cluser-aligned chunk. @end is allowed to exceed s->len only to - * cover last cluster when s->len is not aligned to clusters. + * Do copy of cluser-aligned chunk. Requested region is allowed to exceed s->lencluster-...+ * only to cover last cluster when s->len is not aligned to clusters. * * No sync here: nor bitmap neighter intersecting requests handling, only copy. * * Returns 0 on success. */ static int coroutine_fn block_copy_do_copy(BlockCopyState *s, - int64_t start, int64_t end, + int64_t start, int64_t bytes, bool zeroes, bool *error_is_read) { int ret; - int nbytes = MIN(end, s->len) - start; + int nbytes = MIN(start + bytes, s->len) - start; void *bounce_buffer = NULL;+ assert(start >= 0 && bytes > 0 && INT64_MAX - start >= bytes);assert(QEMU_IS_ALIGNED(start, s->cluster_size)); - assert(QEMU_IS_ALIGNED(end, s->cluster_size)); - assert(end < s->len || end == QEMU_ALIGN_UP(s->len, s->cluster_size)); + assert(QEMU_IS_ALIGNED(bytes, s->cluster_size)); + assert(start + bytes <= s->len ||The '<=' looks correct but I wonder how only '<' worked without assertion failure before.
No difference, if end == s->len, and end is aligned, then len is aligned too and "end == QEMU_ALIGN_UP(s->len, s->cluster_size)" is true. But "<=" looks more native for end and file len.
Was the s->len never aligned to the cluster size?+ start + bytes == QEMU_ALIGN_UP(s->len, s->cluster_size));if (zeroes) {ret = bdrv_co_pwrite_zeroes(s->target, start, nbytes, s->write_flags & @@ -347,7 +349,6 @@ int coroutine_fn block_copy(BlockCopyState *s, bool *error_is_read) { int ret = 0; - int64_t end = bytes + start; /* bytes */ BlockCopyInFlightReq req;/*@@ -358,58 +359,59 @@ int coroutine_fn block_copy(BlockCopyState *s, bdrv_get_aio_context(s->target->bs));assert(QEMU_IS_ALIGNED(start, s->cluster_size));- assert(QEMU_IS_ALIGNED(end, s->cluster_size)); + assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));block_copy_wait_inflight_reqs(s, start, bytes);- block_copy_inflight_req_begin(s, &req, start, end); + block_copy_inflight_req_begin(s, &req, start, bytes);- while (start < end) {- int64_t next_zero, chunk_end, status_bytes; + while (bytes) { + int64_t next_zero, cur_bytes, status_bytes;if (!bdrv_dirty_bitmap_get(s->copy_bitmap, start)) {trace_block_copy_skip(s, start); start += s->cluster_size; + bytes -= s->cluster_size; continue; /* already copied */ }- chunk_end = MIN(end, start + s->copy_size);+ cur_bytes = MIN(bytes, s->copy_size);next_zero = bdrv_dirty_bitmap_next_zero(s->copy_bitmap, start,- chunk_end - start); + cur_bytes); if (next_zero >= 0) { assert(next_zero > start); /* start is dirty */ - assert(next_zero < chunk_end); /* no need to do MIN() */ - chunk_end = next_zero; + assert(next_zero < start + cur_bytes); /* no need to do MIN() */ + cur_bytes = next_zero - start; }- ret = block_copy_block_status(s, start, chunk_end - start,- &status_bytes); + ret = block_copy_block_status(s, start, cur_bytes, &status_bytes); if (s->skip_unallocated && !(ret & BDRV_BLOCK_ALLOCATED)) { bdrv_reset_dirty_bitmap(s->copy_bitmap, start, status_bytes); s->progress_reset_callback(s->progress_opaque); trace_block_copy_skip_range(s, start, status_bytes); start += status_bytes; + bytes -= status_bytes; continue; }- chunk_end = MIN(chunk_end, start + status_bytes);+ cur_bytes = MIN(cur_bytes, status_bytes);trace_block_copy_process(s, start); - bdrv_reset_dirty_bitmap(s->copy_bitmap, start, chunk_end - start);+ bdrv_reset_dirty_bitmap(s->copy_bitmap, start, cur_bytes);- co_get_from_shres(s->mem, chunk_end - start);- ret = block_copy_do_copy(s, start, chunk_end, ret & BDRV_BLOCK_ZERO, + co_get_from_shres(s->mem, cur_bytes); + ret = block_copy_do_copy(s, start, cur_bytes, ret & BDRV_BLOCK_ZERO, error_is_read); - co_put_to_shres(s->mem, chunk_end - start); + co_put_to_shres(s->mem, cur_bytes); if (ret < 0) { - bdrv_set_dirty_bitmap(s->copy_bitmap, start, chunk_end - start); + bdrv_set_dirty_bitmap(s->copy_bitmap, start, cur_bytes); break; }- s->progress_bytes_callback(chunk_end - start, s->progress_opaque);- start = chunk_end; - ret = 0; + s->progress_bytes_callback(cur_bytes, s->progress_opaque); + start += cur_bytes; + bytes -= cur_bytes; }block_copy_inflight_req_end(&req);At the first glance, we would only benefit from the 'while' loop by that substitution to reduce the number of addition operations. Reviewed-by: Andrey Shinkevich <address@hidden>
-- Best regards, Vladimir
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