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dcfbece684
0e2402452f
allowed writes larger than cluster, but that's unsupported for compressed write. Fix it. Fixes:0e2402452f
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-id: 20191029150934.26416-1-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
352 lines
10 KiB
C
352 lines
10 KiB
C
/*
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* block_copy API
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*
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* Copyright (C) 2013 Proxmox Server Solutions
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* Copyright (c) 2019 Virtuozzo International GmbH.
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*
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* Authors:
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* Dietmar Maurer (dietmar@proxmox.com)
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* Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "trace.h"
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#include "qapi/error.h"
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#include "block/block-copy.h"
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#include "sysemu/block-backend.h"
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#include "qemu/units.h"
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#define BLOCK_COPY_MAX_COPY_RANGE (16 * MiB)
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#define BLOCK_COPY_MAX_BUFFER (1 * MiB)
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#define BLOCK_COPY_MAX_MEM (128 * MiB)
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static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s,
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int64_t start,
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int64_t end)
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{
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BlockCopyInFlightReq *req;
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bool waited;
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do {
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waited = false;
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QLIST_FOREACH(req, &s->inflight_reqs, list) {
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if (end > req->start_byte && start < req->end_byte) {
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qemu_co_queue_wait(&req->wait_queue, NULL);
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waited = true;
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break;
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}
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}
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} while (waited);
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}
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static void block_copy_inflight_req_begin(BlockCopyState *s,
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BlockCopyInFlightReq *req,
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int64_t start, int64_t end)
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{
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req->start_byte = start;
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req->end_byte = end;
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qemu_co_queue_init(&req->wait_queue);
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QLIST_INSERT_HEAD(&s->inflight_reqs, req, list);
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}
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static void coroutine_fn block_copy_inflight_req_end(BlockCopyInFlightReq *req)
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{
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QLIST_REMOVE(req, list);
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qemu_co_queue_restart_all(&req->wait_queue);
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}
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void block_copy_state_free(BlockCopyState *s)
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{
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if (!s) {
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return;
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}
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bdrv_release_dirty_bitmap(s->copy_bitmap);
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shres_destroy(s->mem);
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g_free(s);
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}
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BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
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int64_t cluster_size,
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BdrvRequestFlags write_flags, Error **errp)
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{
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BlockCopyState *s;
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BdrvDirtyBitmap *copy_bitmap;
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uint32_t max_transfer =
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MIN_NON_ZERO(INT_MAX,
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MIN_NON_ZERO(source->bs->bl.max_transfer,
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target->bs->bl.max_transfer));
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copy_bitmap = bdrv_create_dirty_bitmap(source->bs, cluster_size, NULL,
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errp);
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if (!copy_bitmap) {
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return NULL;
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}
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bdrv_disable_dirty_bitmap(copy_bitmap);
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s = g_new(BlockCopyState, 1);
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*s = (BlockCopyState) {
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.source = source,
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.target = target,
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.copy_bitmap = copy_bitmap,
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.cluster_size = cluster_size,
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.len = bdrv_dirty_bitmap_size(copy_bitmap),
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.write_flags = write_flags,
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.mem = shres_create(BLOCK_COPY_MAX_MEM),
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};
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if (max_transfer < cluster_size) {
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/*
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* copy_range does not respect max_transfer. We don't want to bother
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* with requests smaller than block-copy cluster size, so fallback to
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* buffered copying (read and write respect max_transfer on their
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* behalf).
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*/
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s->use_copy_range = false;
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s->copy_size = cluster_size;
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} else if (write_flags & BDRV_REQ_WRITE_COMPRESSED) {
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/* Compression supports only cluster-size writes and no copy-range. */
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s->use_copy_range = false;
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s->copy_size = cluster_size;
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} else {
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/*
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* copy_range does not respect max_transfer (it's a TODO), so we factor
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* that in here.
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*/
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s->use_copy_range = true;
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s->copy_size = MIN(MAX(cluster_size, BLOCK_COPY_MAX_COPY_RANGE),
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QEMU_ALIGN_DOWN(max_transfer, cluster_size));
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}
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QLIST_INIT(&s->inflight_reqs);
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return s;
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}
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void block_copy_set_callbacks(
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BlockCopyState *s,
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ProgressBytesCallbackFunc progress_bytes_callback,
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ProgressResetCallbackFunc progress_reset_callback,
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void *progress_opaque)
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{
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s->progress_bytes_callback = progress_bytes_callback;
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s->progress_reset_callback = progress_reset_callback;
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s->progress_opaque = progress_opaque;
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}
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/*
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* block_copy_do_copy
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*
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* Do copy of cluser-aligned chunk. @end is allowed to exceed s->len only to
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* cover last cluster when s->len is not aligned to clusters.
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*
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* No sync here: nor bitmap neighter intersecting requests handling, only copy.
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*
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* Returns 0 on success.
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*/
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static int coroutine_fn block_copy_do_copy(BlockCopyState *s,
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int64_t start, int64_t end,
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bool *error_is_read)
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{
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int ret;
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int nbytes = MIN(end, s->len) - start;
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void *bounce_buffer = NULL;
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assert(QEMU_IS_ALIGNED(start, s->cluster_size));
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assert(QEMU_IS_ALIGNED(end, s->cluster_size));
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assert(end < s->len || end == QEMU_ALIGN_UP(s->len, s->cluster_size));
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if (s->use_copy_range) {
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ret = bdrv_co_copy_range(s->source, start, s->target, start, nbytes,
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0, s->write_flags);
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if (ret < 0) {
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trace_block_copy_copy_range_fail(s, start, ret);
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s->use_copy_range = false;
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s->copy_size = MAX(s->cluster_size, BLOCK_COPY_MAX_BUFFER);
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/* Fallback to read+write with allocated buffer */
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} else {
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goto out;
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}
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}
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/*
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* In case of failed copy_range request above, we may proceed with buffered
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* request larger than BLOCK_COPY_MAX_BUFFER. Still, further requests will
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* be properly limited, so don't care too much.
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*/
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bounce_buffer = qemu_blockalign(s->source->bs, nbytes);
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ret = bdrv_co_pread(s->source, start, nbytes, bounce_buffer, 0);
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if (ret < 0) {
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trace_block_copy_read_fail(s, start, ret);
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if (error_is_read) {
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*error_is_read = true;
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}
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goto out;
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}
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ret = bdrv_co_pwrite(s->target, start, nbytes, bounce_buffer,
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s->write_flags);
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if (ret < 0) {
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trace_block_copy_write_fail(s, start, ret);
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if (error_is_read) {
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*error_is_read = false;
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}
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goto out;
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}
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out:
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qemu_vfree(bounce_buffer);
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return ret;
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}
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/*
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* Check if the cluster starting at offset is allocated or not.
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* return via pnum the number of contiguous clusters sharing this allocation.
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*/
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static int block_copy_is_cluster_allocated(BlockCopyState *s, int64_t offset,
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int64_t *pnum)
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{
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BlockDriverState *bs = s->source->bs;
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int64_t count, total_count = 0;
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int64_t bytes = s->len - offset;
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int ret;
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assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
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while (true) {
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ret = bdrv_is_allocated(bs, offset, bytes, &count);
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if (ret < 0) {
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return ret;
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}
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total_count += count;
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if (ret || count == 0) {
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/*
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* ret: partial segment(s) are considered allocated.
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* otherwise: unallocated tail is treated as an entire segment.
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*/
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*pnum = DIV_ROUND_UP(total_count, s->cluster_size);
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return ret;
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}
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/* Unallocated segment(s) with uncertain following segment(s) */
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if (total_count >= s->cluster_size) {
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*pnum = total_count / s->cluster_size;
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return 0;
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}
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offset += count;
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bytes -= count;
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}
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}
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/*
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* Reset bits in copy_bitmap starting at offset if they represent unallocated
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* data in the image. May reset subsequent contiguous bits.
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* @return 0 when the cluster at @offset was unallocated,
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* 1 otherwise, and -ret on error.
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*/
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int64_t block_copy_reset_unallocated(BlockCopyState *s,
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int64_t offset, int64_t *count)
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{
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int ret;
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int64_t clusters, bytes;
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ret = block_copy_is_cluster_allocated(s, offset, &clusters);
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if (ret < 0) {
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return ret;
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}
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bytes = clusters * s->cluster_size;
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if (!ret) {
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bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, bytes);
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s->progress_reset_callback(s->progress_opaque);
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}
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*count = bytes;
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return ret;
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}
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int coroutine_fn block_copy(BlockCopyState *s,
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int64_t start, uint64_t bytes,
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bool *error_is_read)
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{
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int ret = 0;
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int64_t end = bytes + start; /* bytes */
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int64_t status_bytes;
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BlockCopyInFlightReq req;
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/*
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* block_copy() user is responsible for keeping source and target in same
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* aio context
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*/
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assert(bdrv_get_aio_context(s->source->bs) ==
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bdrv_get_aio_context(s->target->bs));
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assert(QEMU_IS_ALIGNED(start, s->cluster_size));
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assert(QEMU_IS_ALIGNED(end, s->cluster_size));
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block_copy_wait_inflight_reqs(s, start, bytes);
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block_copy_inflight_req_begin(s, &req, start, end);
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while (start < end) {
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int64_t next_zero, chunk_end;
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if (!bdrv_dirty_bitmap_get(s->copy_bitmap, start)) {
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trace_block_copy_skip(s, start);
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start += s->cluster_size;
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continue; /* already copied */
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}
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chunk_end = MIN(end, start + s->copy_size);
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next_zero = bdrv_dirty_bitmap_next_zero(s->copy_bitmap, start,
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chunk_end - start);
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if (next_zero >= 0) {
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assert(next_zero > start); /* start is dirty */
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assert(next_zero < chunk_end); /* no need to do MIN() */
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chunk_end = next_zero;
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}
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if (s->skip_unallocated) {
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ret = block_copy_reset_unallocated(s, start, &status_bytes);
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if (ret == 0) {
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trace_block_copy_skip_range(s, start, status_bytes);
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start += status_bytes;
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continue;
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}
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/* Clamp to known allocated region */
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chunk_end = MIN(chunk_end, start + status_bytes);
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}
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trace_block_copy_process(s, start);
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bdrv_reset_dirty_bitmap(s->copy_bitmap, start, chunk_end - start);
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co_get_from_shres(s->mem, chunk_end - start);
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ret = block_copy_do_copy(s, start, chunk_end, error_is_read);
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co_put_to_shres(s->mem, chunk_end - start);
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if (ret < 0) {
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bdrv_set_dirty_bitmap(s->copy_bitmap, start, chunk_end - start);
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break;
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}
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s->progress_bytes_callback(chunk_end - start, s->progress_opaque);
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start = chunk_end;
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ret = 0;
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}
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block_copy_inflight_req_end(&req);
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return ret;
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}
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