X-Git-Url: https://repo.jachan.dev/qemu.git/blobdiff_plain/1b57488acf1beba157bcd8c926e596342bcb5c60..3119154db04890fdf57022a43cf2ee594fd4da5a:/block/stream.c diff --git a/block/stream.c b/block/stream.c index 81a7ec8ece..aa2e7af98e 100644 --- a/block/stream.c +++ b/block/stream.c @@ -22,36 +22,39 @@ enum { /* - * Size of data buffer for populating the image file. This should be large - * enough to process multiple clusters in a single call, so that populating - * contiguous regions of the image is efficient. + * Maximum chunk size to feed to copy-on-read. This should be + * large enough to process multiple clusters in a single call, so + * that populating contiguous regions of the image is efficient. */ - STREAM_BUFFER_SIZE = 512 * 1024, /* in bytes */ + STREAM_CHUNK = 512 * 1024, /* in bytes */ }; typedef struct StreamBlockJob { BlockJob common; - BlockDriverState *base; + BlockDriverState *bottom; BlockdevOnError on_error; char *backing_file_str; - int bs_flags; + bool bs_read_only; + bool chain_frozen; } StreamBlockJob; static int coroutine_fn stream_populate(BlockBackend *blk, - int64_t offset, uint64_t bytes, - void *buf) + int64_t offset, uint64_t bytes) { - struct iovec iov = { - .iov_base = buf, - .iov_len = bytes, - }; - QEMUIOVector qiov; - assert(bytes < SIZE_MAX); - qemu_iovec_init_external(&qiov, &iov, 1); - /* Copy-on-read the unallocated clusters */ - return blk_co_preadv(blk, offset, qiov.size, &qiov, BDRV_REQ_COPY_ON_READ); + return blk_co_preadv(blk, offset, bytes, NULL, + BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH); +} + +static void stream_abort(Job *job) +{ + StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); + + if (s->chain_frozen) { + BlockJob *bjob = &s->common; + bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->bottom); + } } static int stream_prepare(Job *job) @@ -59,10 +62,13 @@ static int stream_prepare(Job *job) StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); BlockJob *bjob = &s->common; BlockDriverState *bs = blk_bs(bjob->blk); - BlockDriverState *base = s->base; + BlockDriverState *base = backing_bs(s->bottom); Error *local_err = NULL; int ret = 0; + bdrv_unfreeze_backing_chain(bs, s->bottom); + s->chain_frozen = false; + if (bs->backing) { const char *base_id = NULL, *base_fmt = NULL; if (base) { @@ -71,8 +77,8 @@ static int stream_prepare(Job *job) base_fmt = base->drv->format_name; } } - ret = bdrv_change_backing_file(bs, base_id, base_fmt); bdrv_set_backing_hd(bs, base, &local_err); + ret = bdrv_change_backing_file(bs, base_id, base_fmt); if (local_err) { error_report_err(local_err); return -EPERM; @@ -89,10 +95,10 @@ static void stream_clean(Job *job) BlockDriverState *bs = blk_bs(bjob->blk); /* Reopen the image back in read-only mode if necessary */ - if (s->bs_flags != bdrv_get_flags(bs)) { + if (s->bs_read_only) { /* Give up write permissions before making it read-only */ blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort); - bdrv_reopen(bs, s->bs_flags, NULL); + bdrv_reopen_set_read_only(bs, true, NULL); } g_free(s->backing_file_str); @@ -103,39 +109,36 @@ static int coroutine_fn stream_run(Job *job, Error **errp) StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); BlockBackend *blk = s->common.blk; BlockDriverState *bs = blk_bs(blk); - BlockDriverState *base = s->base; + bool enable_cor = !backing_bs(s->bottom); int64_t len; int64_t offset = 0; uint64_t delay_ns = 0; int error = 0; - int ret = 0; int64_t n = 0; /* bytes */ - void *buf; - if (!bs->backing) { - goto out; + if (bs == s->bottom) { + /* Nothing to stream */ + return 0; } len = bdrv_getlength(bs); if (len < 0) { - ret = len; - goto out; + return len; } job_progress_set_remaining(&s->common.job, len); - buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE); - /* Turn on copy-on-read for the whole block device so that guest read * requests help us make progress. Only do this when copying the entire * backing chain since the copy-on-read operation does not take base into * account. */ - if (!base) { + if (enable_cor) { bdrv_enable_copy_on_read(bs); } for ( ; offset < len; offset += n) { bool copy; + int ret; /* Note that even when no rate limit is applied we need to yield * with no pending I/O here so that bdrv_drain_all() returns. @@ -147,15 +150,14 @@ static int coroutine_fn stream_run(Job *job, Error **errp) copy = false; - ret = bdrv_is_allocated(bs, offset, STREAM_BUFFER_SIZE, &n); + ret = bdrv_is_allocated(bs, offset, STREAM_CHUNK, &n); if (ret == 1) { /* Allocated in the top, no need to copy. */ } else if (ret >= 0) { /* Copy if allocated in the intermediate images. Limit to the * known-unallocated area [offset, offset+n*BDRV_SECTOR_SIZE). */ - ret = bdrv_is_allocated_above(backing_bs(bs), base, + ret = bdrv_is_allocated_above(backing_bs(bs), s->bottom, true, offset, n, &n); - /* Finish early if end of backing file has been reached */ if (ret == 0 && n == 0) { n = len - offset; @@ -165,7 +167,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp) } trace_stream_one_iteration(s, offset, n, ret); if (copy) { - ret = stream_populate(blk, offset, n, buf); + ret = stream_populate(blk, offset, n); } if (ret < 0) { BlockErrorAction action = @@ -181,7 +183,6 @@ static int coroutine_fn stream_run(Job *job, Error **errp) break; } } - ret = 0; /* Publish progress */ job_progress_update(&s->common.job, n); @@ -192,18 +193,12 @@ static int coroutine_fn stream_run(Job *job, Error **errp) } } - if (!base) { + if (enable_cor) { bdrv_disable_copy_on_read(bs); } - /* Do not remove the backing file if an error was there but ignored. */ - ret = error; - - qemu_vfree(buf); - -out: - /* Modify backing chain and close BDSes in main loop */ - return ret; + /* Do not remove the backing file if an error was there but ignored. */ + return error; } static const BlockJobDriver stream_job_driver = { @@ -213,9 +208,9 @@ static const BlockJobDriver stream_job_driver = { .free = block_job_free, .run = stream_run, .prepare = stream_prepare, + .abort = stream_abort, .clean = stream_clean, .user_resume = block_job_user_resume, - .drain = block_job_drain, }, }; @@ -226,13 +221,20 @@ void stream_start(const char *job_id, BlockDriverState *bs, { StreamBlockJob *s; BlockDriverState *iter; - int orig_bs_flags; + bool bs_read_only; + int basic_flags = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED; + BlockDriverState *bottom = bdrv_find_overlay(bs, base); + + if (bdrv_freeze_backing_chain(bs, bottom, errp) < 0) { + return; + } /* Make sure that the image is opened in read-write mode */ - orig_bs_flags = bdrv_get_flags(bs); - if (!(orig_bs_flags & BDRV_O_RDWR)) { - if (bdrv_reopen(bs, orig_bs_flags | BDRV_O_RDWR, errp) != 0) { - return; + bs_read_only = bdrv_is_read_only(bs); + if (bs_read_only) { + if (bdrv_reopen_set_read_only(bs, false, errp) != 0) { + bs_read_only = false; + goto fail; } } @@ -240,10 +242,8 @@ void stream_start(const char *job_id, BlockDriverState *bs, * already have our own plans. Also don't allow resize as the image size is * queried only at the job start and then cached. */ s = block_job_create(job_id, &stream_job_driver, NULL, bs, - BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | - BLK_PERM_GRAPH_MOD, - BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | - BLK_PERM_WRITE, + basic_flags | BLK_PERM_GRAPH_MOD, + basic_flags | BLK_PERM_WRITE, speed, creation_flags, NULL, NULL, errp); if (!s) { goto fail; @@ -251,17 +251,21 @@ void stream_start(const char *job_id, BlockDriverState *bs, /* Block all intermediate nodes between bs and base, because they will * disappear from the chain after this operation. The streaming job reads - * every block only once, assuming that it doesn't change, so block writes - * and resizes. */ + * every block only once, assuming that it doesn't change, so forbid writes + * and resizes. Reassign the base node pointer because the backing BS of the + * bottom node might change after the call to bdrv_reopen_set_read_only() + * due to parallel block jobs running. + */ + base = backing_bs(bottom); for (iter = backing_bs(bs); iter && iter != base; iter = backing_bs(iter)) { block_job_add_bdrv(&s->common, "intermediate node", iter, 0, - BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED, - &error_abort); + basic_flags, &error_abort); } - s->base = base; + s->bottom = bottom; s->backing_file_str = g_strdup(backing_file_str); - s->bs_flags = orig_bs_flags; + s->bs_read_only = bs_read_only; + s->chain_frozen = true; s->on_error = on_error; trace_stream_start(bs, base, s); @@ -269,7 +273,8 @@ void stream_start(const char *job_id, BlockDriverState *bs, return; fail: - if (orig_bs_flags != bdrv_get_flags(bs)) { - bdrv_reopen(bs, orig_bs_flags, NULL); + if (bs_read_only) { + bdrv_reopen_set_read_only(bs, true, NULL); } + bdrv_unfreeze_backing_chain(bs, bottom); }