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[Qemu-devel] [PATCH v2 10/11] block: let commit blockjob run in BDS AioC
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v2 10/11] block: let commit blockjob run in BDS AioContext |
Date: |
Tue, 21 Oct 2014 12:03:59 +0100 |
The commit block job must run in the BlockDriverState AioContext so that
it works with dataplane.
Acquire the AioContext in blockdev.c so starting the block job is safe.
One detail here is that the bdrv_drain_all() must be moved inside the
aio_context_acquire() region so requests cannot sneak in between the
drain and acquire.
The completion code in block/commit.c must perform backing chain
manipulation and bdrv_reopen() from the main loop. Use
block_job_defer_to_main_loop() to achieve that.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/commit.c | 70 ++++++++++++++++++++++++++++++++++++----------------------
blockdev.c | 29 ++++++++++++++++--------
2 files changed, 64 insertions(+), 35 deletions(-)
diff --git a/block/commit.c b/block/commit.c
index 91517d3..6f42105 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -60,17 +60,50 @@ static int coroutine_fn commit_populate(BlockDriverState
*bs,
return 0;
}
-static void coroutine_fn commit_run(void *opaque)
+typedef struct {
+ int ret;
+} CommitCompleteData;
+
+static void commit_complete(BlockJob *job, void *opaque)
{
- CommitBlockJob *s = opaque;
+ CommitBlockJob *s = container_of(job, CommitBlockJob, common);
+ CommitCompleteData *data = opaque;
BlockDriverState *active = s->active;
BlockDriverState *top = s->top;
BlockDriverState *base = s->base;
BlockDriverState *overlay_bs;
+ int ret = data->ret;
+
+ if (!block_job_is_cancelled(&s->common) && ret == 0) {
+ /* success */
+ ret = bdrv_drop_intermediate(active, top, base, s->backing_file_str);
+ }
+
+ /* restore base open flags here if appropriate (e.g., change the base back
+ * to r/o). These reopens do not need to be atomic, since we won't abort
+ * even on failure here */
+ if (s->base_flags != bdrv_get_flags(base)) {
+ bdrv_reopen(base, s->base_flags, NULL);
+ }
+ overlay_bs = bdrv_find_overlay(active, top);
+ if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
+ bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
+ }
+ g_free(s->backing_file_str);
+ block_job_completed(&s->common, ret);
+ g_free(data);
+}
+
+static void coroutine_fn commit_run(void *opaque)
+{
+ CommitBlockJob *s = opaque;
+ CommitCompleteData *data;
+ BlockDriverState *top = s->top;
+ BlockDriverState *base = s->base;
int64_t sector_num, end;
int ret = 0;
int n = 0;
- void *buf;
+ void *buf = NULL;
int bytes_written = 0;
int64_t base_len;
@@ -78,18 +111,18 @@ static void coroutine_fn commit_run(void *opaque)
if (s->common.len < 0) {
- goto exit_restore_reopen;
+ goto out;
}
ret = base_len = bdrv_getlength(base);
if (base_len < 0) {
- goto exit_restore_reopen;
+ goto out;
}
if (base_len < s->common.len) {
ret = bdrv_truncate(base, s->common.len);
if (ret) {
- goto exit_restore_reopen;
+ goto out;
}
}
@@ -128,7 +161,7 @@ wait:
if (s->on_error == BLOCKDEV_ON_ERROR_STOP ||
s->on_error == BLOCKDEV_ON_ERROR_REPORT||
(s->on_error == BLOCKDEV_ON_ERROR_ENOSPC && ret == -ENOSPC)) {
- goto exit_free_buf;
+ goto out;
} else {
n = 0;
continue;
@@ -140,27 +173,12 @@ wait:
ret = 0;
- if (!block_job_is_cancelled(&s->common) && sector_num == end) {
- /* success */
- ret = bdrv_drop_intermediate(active, top, base, s->backing_file_str);
- }
-
-exit_free_buf:
+out:
qemu_vfree(buf);
-exit_restore_reopen:
- /* restore base open flags here if appropriate (e.g., change the base back
- * to r/o). These reopens do not need to be atomic, since we won't abort
- * even on failure here */
- if (s->base_flags != bdrv_get_flags(base)) {
- bdrv_reopen(base, s->base_flags, NULL);
- }
- overlay_bs = bdrv_find_overlay(active, top);
- if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
- bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
- }
- g_free(s->backing_file_str);
- block_job_completed(&s->common, ret);
+ data = g_malloc(sizeof(*data));
+ data->ret = ret;
+ block_job_defer_to_main_loop(&s->common, commit_complete, data);
}
static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp)
diff --git a/blockdev.c b/blockdev.c
index 2bd6c58..09b2567 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2051,6 +2051,7 @@ void qmp_block_commit(const char *device,
{
BlockDriverState *bs;
BlockDriverState *base_bs, *top_bs;
+ AioContext *aio_context;
Error *local_err = NULL;
/* This will be part of the QMP command, if/when the
* BlockdevOnError change for blkmirror makes it in
@@ -2061,9 +2062,6 @@ void qmp_block_commit(const char *device,
speed = 0;
}
- /* drain all i/o before commits */
- bdrv_drain_all();
-
/* Important Note:
* libvirt relies on the DeviceNotFound error class in order to probe for
* live commit feature versions; for this to work, we must make sure to
@@ -2075,8 +2073,14 @@ void qmp_block_commit(const char *device,
return;
}
+ aio_context = bdrv_get_aio_context(bs);
+ aio_context_acquire(aio_context);
+
+ /* drain all i/o before commits */
+ bdrv_drain_all();
+
if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT, errp)) {
- return;
+ goto out;
}
/* default top_bs is the active layer */
@@ -2090,9 +2094,11 @@ void qmp_block_commit(const char *device,
if (top_bs == NULL) {
error_setg(errp, "Top image file %s not found", top ? top : "NULL");
- return;
+ goto out;
}
+ assert(bdrv_get_aio_context(top_bs) == aio_context);
+
if (has_base && base) {
base_bs = bdrv_find_backing_image(top_bs, base);
} else {
@@ -2101,20 +2107,22 @@ void qmp_block_commit(const char *device,
if (base_bs == NULL) {
error_set(errp, QERR_BASE_NOT_FOUND, base ? base : "NULL");
- return;
+ goto out;
}
+ assert(bdrv_get_aio_context(base_bs) == aio_context);
+
/* Do not allow attempts to commit an image into itself */
if (top_bs == base_bs) {
error_setg(errp, "cannot commit an image into itself");
- return;
+ goto out;
}
if (top_bs == bs) {
if (has_backing_file) {
error_setg(errp, "'backing-file' specified,"
" but 'top' is the active layer");
- return;
+ goto out;
}
commit_active_start(bs, base_bs, speed, on_error, block_job_cb,
bs, &local_err);
@@ -2124,8 +2132,11 @@ void qmp_block_commit(const char *device,
}
if (local_err != NULL) {
error_propagate(errp, local_err);
- return;
+ goto out;
}
+
+out:
+ aio_context_release(aio_context);
}
void qmp_drive_backup(const char *device, const char *target,
--
1.9.3
- Re: [Qemu-devel] [PATCH v2 02/11] blockdev: acquire AioContext in do_qmp_query_block_jobs_one(), (continued)
- [Qemu-devel] [PATCH v2 03/11] blockdev: acquire AioContext in blockdev_mark_auto_del(), Stefan Hajnoczi, 2014/10/21
- [Qemu-devel] [PATCH v2 04/11] blockdev: add note that block_job_cb() must be thread-safe, Stefan Hajnoczi, 2014/10/21
- [Qemu-devel] [PATCH v2 05/11] blockjob: add block_job_defer_to_main_loop(), Stefan Hajnoczi, 2014/10/21
- [Qemu-devel] [PATCH v2 06/11] block: add bdrv_drain(), Stefan Hajnoczi, 2014/10/21
- [Qemu-devel] [PATCH v2 07/11] block: let backup blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/10/21
- [Qemu-devel] [PATCH v2 09/11] block: let mirror blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/10/21
- [Qemu-devel] [PATCH v2 08/11] block: let stream blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/10/21
- [Qemu-devel] [PATCH v2 10/11] block: let commit blockjob run in BDS AioContext,
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v2 11/11] block: declare blockjobs and dataplane friends!, Stefan Hajnoczi, 2014/10/21
- Re: [Qemu-devel] [PATCH v2 00/11] block: allow blockjobs to coexist with dataplane, Stefan Hajnoczi, 2014/10/29