diff options
Diffstat (limited to 'block/commit.c')
| -rw-r--r-- | block/commit.c | 176 |
1 files changed, 153 insertions, 23 deletions
diff --git a/block/commit.c b/block/commit.c index c284e8535d..22a0a4db98 100644 --- a/block/commit.c +++ b/block/commit.c @@ -36,6 +36,7 @@ typedef struct CommitBlockJob { BlockJob common; RateLimit limit; BlockDriverState *active; + BlockDriverState *commit_top_bs; BlockBackend *top; BlockBackend *base; BlockdevOnError on_error; @@ -83,12 +84,23 @@ static void commit_complete(BlockJob *job, void *opaque) BlockDriverState *active = s->active; BlockDriverState *top = blk_bs(s->top); BlockDriverState *base = blk_bs(s->base); - BlockDriverState *overlay_bs = bdrv_find_overlay(active, top); + BlockDriverState *overlay_bs = bdrv_find_overlay(active, s->commit_top_bs); int ret = data->ret; + bool remove_commit_top_bs = false; + + /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before + * the normal backing chain can be restored. */ + blk_unref(s->base); if (!block_job_is_cancelled(&s->common) && ret == 0) { /* success */ - ret = bdrv_drop_intermediate(active, top, base, s->backing_file_str); + ret = bdrv_drop_intermediate(active, s->commit_top_bs, base, + s->backing_file_str); + } else if (overlay_bs) { + /* XXX Can (or should) we somehow keep 'consistent read' blocked even + * after the failed/cancelled commit job is gone? If we already wrote + * something to base, the intermediate images aren't valid any more. */ + remove_commit_top_bs = true; } /* restore base open flags here if appropriate (e.g., change the base back @@ -102,9 +114,15 @@ static void commit_complete(BlockJob *job, void *opaque) } g_free(s->backing_file_str); blk_unref(s->top); - blk_unref(s->base); block_job_completed(&s->common, ret); g_free(data); + + /* If bdrv_drop_intermediate() didn't already do that, remove the commit + * filter driver from the backing chain. Do this as the final step so that + * the 'consistent read' permission can be granted. */ + if (remove_commit_top_bs) { + bdrv_set_backing_hd(overlay_bs, top, &error_abort); + } } static void coroutine_fn commit_run(void *opaque) @@ -208,10 +226,38 @@ static const BlockJobDriver commit_job_driver = { .start = commit_run, }; +static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs, + uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) +{ + return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); +} + +static void bdrv_commit_top_close(BlockDriverState *bs) +{ +} + +static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c, + const BdrvChildRole *role, + uint64_t perm, uint64_t shared, + uint64_t *nperm, uint64_t *nshared) +{ + *nperm = 0; + *nshared = BLK_PERM_ALL; +} + +/* Dummy node that provides consistent read to its users without requiring it + * from its backing file and that allows writes on the backing file chain. */ +static BlockDriver bdrv_commit_top = { + .format_name = "commit_top", + .bdrv_co_preadv = bdrv_commit_top_preadv, + .bdrv_close = bdrv_commit_top_close, + .bdrv_child_perm = bdrv_commit_top_child_perm, +}; + void commit_start(const char *job_id, BlockDriverState *bs, BlockDriverState *base, BlockDriverState *top, int64_t speed, BlockdevOnError on_error, const char *backing_file_str, - Error **errp) + const char *filter_node_name, Error **errp) { CommitBlockJob *s; BlockReopenQueue *reopen_queue = NULL; @@ -219,7 +265,9 @@ void commit_start(const char *job_id, BlockDriverState *bs, int orig_base_flags; BlockDriverState *iter; BlockDriverState *overlay_bs; + BlockDriverState *commit_top_bs = NULL; Error *local_err = NULL; + int ret; assert(top != bs); if (top == base) { @@ -234,8 +282,8 @@ void commit_start(const char *job_id, BlockDriverState *bs, return; } - s = block_job_create(job_id, &commit_job_driver, bs, speed, - BLOCK_JOB_DEFAULT, NULL, NULL, errp); + s = block_job_create(job_id, &commit_job_driver, bs, 0, BLK_PERM_ALL, + speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp); if (!s) { return; } @@ -256,30 +304,70 @@ void commit_start(const char *job_id, BlockDriverState *bs, bdrv_reopen_multiple(bdrv_get_aio_context(bs), reopen_queue, &local_err); if (local_err != NULL) { error_propagate(errp, local_err); - block_job_unref(&s->common); - return; + goto fail; } } + /* Insert commit_top block node above top, so we can block consistent read + * on the backing chain below it */ + commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0, + errp); + if (commit_top_bs == NULL) { + goto fail; + } + + bdrv_set_backing_hd(commit_top_bs, top, &error_abort); + bdrv_set_backing_hd(overlay_bs, commit_top_bs, &error_abort); + + s->commit_top_bs = commit_top_bs; + bdrv_unref(commit_top_bs); /* Block all nodes between top and base, because they will * disappear from the chain after this operation. */ assert(bdrv_chain_contains(top, base)); - for (iter = top; iter != backing_bs(base); iter = backing_bs(iter)) { - block_job_add_bdrv(&s->common, iter); + for (iter = top; iter != base; iter = backing_bs(iter)) { + /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves + * at s->base (if writes are blocked for a node, they are also blocked + * for its backing file). The other options would be a second filter + * driver above s->base. */ + ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, + BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, + errp); + if (ret < 0) { + goto fail; + } + } + + ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); + if (ret < 0) { + goto fail; } + /* overlay_bs must be blocked because it needs to be modified to - * update the backing image string, but if it's the root node then - * don't block it again */ - if (bs != overlay_bs) { - block_job_add_bdrv(&s->common, overlay_bs); + * update the backing image string. */ + ret = block_job_add_bdrv(&s->common, "overlay of top", overlay_bs, + BLK_PERM_GRAPH_MOD, BLK_PERM_ALL, errp); + if (ret < 0) { + goto fail; } - s->base = blk_new(); - blk_insert_bs(s->base, base); + s->base = blk_new(BLK_PERM_CONSISTENT_READ + | BLK_PERM_WRITE + | BLK_PERM_RESIZE, + BLK_PERM_CONSISTENT_READ + | BLK_PERM_GRAPH_MOD + | BLK_PERM_WRITE_UNCHANGED); + ret = blk_insert_bs(s->base, base, errp); + if (ret < 0) { + goto fail; + } - s->top = blk_new(); - blk_insert_bs(s->top, top); + /* Required permissions are already taken with block_job_add_bdrv() */ + s->top = blk_new(0, BLK_PERM_ALL); + blk_insert_bs(s->top, top, errp); + if (ret < 0) { + goto fail; + } s->active = bs; @@ -292,6 +380,19 @@ void commit_start(const char *job_id, BlockDriverState *bs, trace_commit_start(bs, base, top, s); block_job_start(&s->common); + return; + +fail: + if (s->base) { + blk_unref(s->base); + } + if (s->top) { + blk_unref(s->top); + } + if (commit_top_bs) { + bdrv_set_backing_hd(overlay_bs, top, &error_abort); + } + block_job_unref(&s->common); } @@ -301,11 +402,14 @@ void commit_start(const char *job_id, BlockDriverState *bs, int bdrv_commit(BlockDriverState *bs) { BlockBackend *src, *backing; + BlockDriverState *backing_file_bs = NULL; + BlockDriverState *commit_top_bs = NULL; BlockDriver *drv = bs->drv; int64_t sector, total_sectors, length, backing_length; int n, ro, open_flags; int ret = 0; uint8_t *buf = NULL; + Error *local_err = NULL; if (!drv) return -ENOMEDIUM; @@ -328,11 +432,33 @@ int bdrv_commit(BlockDriverState *bs) } } - src = blk_new(); - blk_insert_bs(src, bs); + src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL); + backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL); - backing = blk_new(); - blk_insert_bs(backing, bs->backing->bs); + ret = blk_insert_bs(src, bs, &local_err); + if (ret < 0) { + error_report_err(local_err); + goto ro_cleanup; + } + + /* Insert commit_top block node above backing, so we can write to it */ + backing_file_bs = backing_bs(bs); + + commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR, + &local_err); + if (commit_top_bs == NULL) { + error_report_err(local_err); + goto ro_cleanup; + } + + bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort); + bdrv_set_backing_hd(bs, commit_top_bs, &error_abort); + + ret = blk_insert_bs(backing, backing_file_bs, &local_err); + if (ret < 0) { + error_report_err(local_err); + goto ro_cleanup; + } length = blk_getlength(src); if (length < 0) { @@ -404,8 +530,12 @@ int bdrv_commit(BlockDriverState *bs) ro_cleanup: qemu_vfree(buf); - blk_unref(src); blk_unref(backing); + if (backing_file_bs) { + bdrv_set_backing_hd(bs, backing_file_bs, &error_abort); + } + bdrv_unref(commit_top_bs); + blk_unref(src); if (ro) { /* ignoring error return here */ |