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[Qemu-block] [PATCH 1/2] block: use internal filter node in backup
|
From: |
Manos Pitsidianakis |
|
Subject: |
[Qemu-block] [PATCH 1/2] block: use internal filter node in backup |
|
Date: |
Tue, 15 Aug 2017 09:19:20 +0300 |
block/backup.c currently uses before write notifiers on the targeted
node. We can create a filter node instead to intercept write requests
for the backup job on the BDS level, instead of the BlockBackend level.
Signed-off-by: Manos Pitsidianakis <address@hidden>
---
block.c | 89 +++++++++++++++++--
block/backup.c | 207 ++++++++++++++++++++++++++++++++++++++++-----
block/io.c | 10 +--
block/mirror.c | 4 +-
blockdev.c | 2 +-
include/block/block.h | 8 +-
tests/qemu-iotests/141.out | 2 +-
7 files changed, 277 insertions(+), 45 deletions(-)
diff --git a/block.c b/block.c
index 2de1c29eb3..81bd51b670 100644
--- a/block.c
+++ b/block.c
@@ -2088,6 +2088,38 @@ static void bdrv_parent_cb_resize(BlockDriverState *bs)
}
/*
+ * Sets the file link of a BDS. A new reference is created; callers
+ * which don't need their own reference any more must call bdrv_unref().
+ */
+void bdrv_set_file(BlockDriverState *bs, BlockDriverState *file_bs,
+ Error **errp)
+{
+ if (file_bs) {
+ bdrv_ref(file_bs);
+ }
+
+ if (bs->file) {
+ bdrv_unref_child(bs, bs->file);
+ }
+
+ if (!file_bs) {
+ bs->file = NULL;
+ goto out;
+ }
+
+ bs->file = bdrv_attach_child(bs, file_bs, "file", &child_file,
+ errp);
+ if (!bs->file) {
+ bdrv_unref(file_bs);
+ }
+
+ bdrv_refresh_filename(bs);
+
+out:
+ bdrv_refresh_limits(bs, NULL);
+}
+
+/*
* Sets the backing file link of a BDS. A new reference is created; callers
* which don't need their own reference any more must call bdrv_unref().
*/
@@ -2355,12 +2387,12 @@ static BlockDriverState
*bdrv_append_temp_snapshot(BlockDriverState *bs,
goto out;
}
- /* bdrv_append() consumes a strong reference to bs_snapshot
+ /* bdrv_append_backing() consumes a strong reference to bs_snapshot
* (i.e. it will call bdrv_unref() on it) even on error, so in
* order to be able to return one, we have to increase
* bs_snapshot's refcount here */
bdrv_ref(bs_snapshot);
- bdrv_append(bs_snapshot, bs, &local_err);
+ bdrv_append_backing(bs_snapshot, bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
bs_snapshot = NULL;
@@ -3142,7 +3174,7 @@ static bool should_update_child(BdrvChild *c,
BlockDriverState *to)
return false;
}
- if (c->role == &child_backing) {
+ if (c->role == &child_backing || c->role == &child_file) {
/* If @from is a backing file of @to, ignore the child to avoid
* creating a loop. We only want to change the pointer of other
* parents. */
@@ -3213,6 +3245,45 @@ out:
}
/*
+ * Add new bs node at the top of a BDS chain while the chain is
+ * live, while keeping required fields on the top layer.
+ *
+ * This will modify the BlockDriverState fields, and swap contents
+ * between bs_new and bs_top. Both bs_new and bs_top are modified.
+ *
+ * bs_new must not be attached to a BlockBackend.
+ *
+ * bdrv_append_file() takes ownership of a bs_new reference and unrefs it
+ * because that's what the callers commonly need. bs_new will be referenced by
+ * the old parents of bs_top after bdrv_append_file() returns. If the caller
+ * needs to keep a reference of its own, it must call bdrv_ref().
+ */
+void bdrv_append_file(BlockDriverState *bs_new, BlockDriverState *bs_top,
+ Error **errp)
+{
+ Error *local_err = NULL;
+
+ bdrv_ref(bs_top);
+ bdrv_set_file(bs_new, bs_top, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ bdrv_set_file(bs_new, NULL, &error_abort);
+ goto out;
+ }
+ bdrv_replace_node(bs_top, bs_new, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ goto out;
+ }
+
+ /* bs_new is now referenced by its new parents, we don't need the
+ * additional reference any more. */
+out:
+ bdrv_unref(bs_top);
+ bdrv_unref(bs_new);
+}
+
+/*
* Add new bs contents at the top of an image chain while the chain is
* live, while keeping required fields on the top layer.
*
@@ -3223,13 +3294,13 @@ out:
*
* This function does not create any image files.
*
- * bdrv_append() takes ownership of a bs_new reference and unrefs it because
- * that's what the callers commonly need. bs_new will be referenced by the old
- * parents of bs_top after bdrv_append() returns. If the caller needs to keep a
- * reference of its own, it must call bdrv_ref().
+ * bdrv_append_backing() takes ownership of a bs_new reference and unrefs it
+ * because that's what the callers commonly need. bs_new will be referenced by
+ * the old parents of bs_top after bdrv_append_backing() returns. If the caller
+ * needs to keep a reference of its own, it must call bdrv_ref().
*/
-void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
- Error **errp)
+void bdrv_append_backing(BlockDriverState *bs_new, BlockDriverState *bs_top,
+ Error **errp)
{
Error *local_err = NULL;
diff --git a/block/backup.c b/block/backup.c
index 504a089150..0828d522b6 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -43,7 +43,7 @@ typedef struct BackupBlockJob {
unsigned long *done_bitmap;
int64_t cluster_size;
bool compress;
- NotifierWithReturn before_write;
+ BlockDriverState *filter;
QLIST_HEAD(, CowRequest) inflight_reqs;
} BackupBlockJob;
@@ -174,20 +174,6 @@ out:
return ret;
}
-static int coroutine_fn backup_before_write_notify(
- NotifierWithReturn *notifier,
- void *opaque)
-{
- BackupBlockJob *job = container_of(notifier, BackupBlockJob, before_write);
- BdrvTrackedRequest *req = opaque;
-
- assert(req->bs == blk_bs(job->common.blk));
- assert(QEMU_IS_ALIGNED(req->offset, BDRV_SECTOR_SIZE));
- assert(QEMU_IS_ALIGNED(req->bytes, BDRV_SECTOR_SIZE));
-
- return backup_do_cow(job, req->offset, req->bytes, NULL, true);
-}
-
static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common);
@@ -202,7 +188,8 @@ static void backup_set_speed(BlockJob *job, int64_t speed,
Error **errp)
static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
{
BdrvDirtyBitmap *bm;
- BlockDriverState *bs = blk_bs(job->common.blk);
+ BlockDriverState *bs = child_bs(blk_bs(job->common.blk));
+ assert(bs);
if (ret < 0 || block_job_is_cancelled(&job->common)) {
/* Merge the successor back into the parent, delete nothing. */
@@ -234,9 +221,31 @@ static void backup_abort(BlockJob *job)
static void backup_clean(BlockJob *job)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common);
+ BlockDriverState *bs = child_bs(s->filter),
+ *filter = s->filter;
+
assert(s->target);
blk_unref(s->target);
s->target = NULL;
+
+ /* make sure nothing goes away while removing filter */
+ bdrv_ref(filter);
+ bdrv_ref(bs);
+ bdrv_drained_begin(bs);
+
+ block_job_remove_all_bdrv(job);
+ bdrv_child_try_set_perm(filter->file, 0, BLK_PERM_ALL,
+ &error_abort);
+ bdrv_replace_node(filter, bs, &error_abort);
+
+ blk_remove_bs(job->blk);
+ blk_set_perm(job->blk, 0, BLK_PERM_ALL, &error_abort);
+ blk_insert_bs(job->blk, filter, &error_abort);
+
+ bdrv_drained_end(bs);
+ bdrv_unref(filter);
+ bdrv_unref(bs);
+ s->filter = NULL;
}
static void backup_attached_aio_context(BlockJob *job, AioContext *aio_context)
@@ -421,6 +430,18 @@ out:
return ret;
}
+static void backup_top_enable(BackupBlockJob *job)
+{
+ BlockDriverState *bs = job->filter;
+ bs->opaque = job;
+}
+
+static void backup_top_disable(BackupBlockJob *job)
+{
+ BlockDriverState *bs = job->filter;
+ bs->opaque = NULL;
+}
+
static void coroutine_fn backup_run(void *opaque)
{
BackupBlockJob *job = opaque;
@@ -435,13 +456,12 @@ static void coroutine_fn backup_run(void *opaque)
job->done_bitmap = bitmap_new(DIV_ROUND_UP(job->common.len,
job->cluster_size));
- job->before_write.notify = backup_before_write_notify;
- bdrv_add_before_write_notifier(bs, &job->before_write);
+ backup_top_enable(job);
if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
while (!block_job_is_cancelled(&job->common)) {
- /* Yield until the job is cancelled. We just let our before_write
- * notify callback service CoW requests. */
+ /* Yield until the job is cancelled. We just let our backup_top
+ * filter service CoW requests. */
block_job_yield(&job->common);
}
} else if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
@@ -507,8 +527,7 @@ static void coroutine_fn backup_run(void *opaque)
}
}
}
-
- notifier_with_return_remove(&job->before_write);
+ backup_top_disable(job);
/* wait until pending backup_do_cow() calls have completed */
qemu_co_rwlock_wrlock(&job->flush_rwlock);
@@ -532,6 +551,124 @@ static const BlockJobDriver backup_job_driver = {
.drain = backup_drain,
};
+static int coroutine_fn backup_top_co_preadv(BlockDriverState *bs,
+ uint64_t offset,
+ uint64_t bytes,
+ QEMUIOVector *qiov, int flags)
+{
+ return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
+}
+
+static int coroutine_fn backup_top_co_pwritev(BlockDriverState *bs,
+ uint64_t offset,
+ uint64_t bytes,
+ QEMUIOVector *qiov, int flags)
+{
+ int ret = 0;
+ BackupBlockJob *job = bs->opaque;
+ if (job) {
+ assert(bs == blk_bs(job->common.blk));
+ assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
+ assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
+ ret = backup_do_cow(job, offset, bytes, NULL, true);
+ }
+
+ return ret < 0 ? ret : bdrv_co_pwritev(bs->file, offset, bytes,
+ qiov, flags);
+}
+
+static int coroutine_fn backup_top_co_pwrite_zeroes(BlockDriverState *bs,
+ int64_t offset,
+ int bytes,
+ BdrvRequestFlags flags)
+{
+ int ret = 0;
+ BackupBlockJob *job = bs->opaque;
+ if (job) {
+ assert(bs == blk_bs(job->common.blk));
+ assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
+ assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
+ ret = backup_do_cow(job, offset, bytes, NULL, true);
+ }
+
+ return ret < 0 ? ret : bdrv_co_pwrite_zeroes(bs->file, offset, bytes,
+ flags);
+}
+
+static int coroutine_fn backup_top_co_pdiscard(BlockDriverState *bs,
+ int64_t offset, int bytes)
+{
+ int ret = 0;
+ BackupBlockJob *job = bs->opaque;
+ if (job) {
+ assert(bs == blk_bs(job->common.blk));
+ assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
+ assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
+ ret = backup_do_cow(job, offset, bytes, NULL, true);
+ }
+
+ return ret < 0 ? ret : bdrv_co_pdiscard(bs->file->bs, offset, bytes);
+}
+
+static int backup_top_co_flush(BlockDriverState *bs)
+{
+ return bdrv_co_flush(bs->file->bs);
+}
+
+static int backup_top_open(BlockDriverState *bs, QDict *options,
+ int flags, Error **errp)
+{
+ return 0;
+}
+
+static void backup_top_close(BlockDriverState *bs)
+{
+}
+
+static int64_t backup_top_getlength(BlockDriverState *bs)
+{
+ return bs->file ? bdrv_getlength(bs->file->bs) : 0;
+}
+
+static bool backup_recurse_is_first_non_filter(BlockDriverState *bs,
+ BlockDriverState *candidate)
+{
+ return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
+}
+
+static int64_t coroutine_fn backup_co_get_block_status(BlockDriverState *bs,
+ int64_t sector_num,
+ int nb_sectors,
+ int *pnum,
+ BlockDriverState **file)
+{
+ assert(bs->file && bs->file->bs);
+ *pnum = nb_sectors;
+ *file = bs->file->bs;
+ return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID |
+ (sector_num << BDRV_SECTOR_BITS);
+}
+static BlockDriver backup_top = {
+ .format_name = "backup-top",
+ .instance_size = sizeof(BackupBlockJob *),
+
+ .bdrv_open = backup_top_open,
+ .bdrv_close = backup_top_close,
+
+ .bdrv_co_flush = backup_top_co_flush,
+ .bdrv_co_preadv = backup_top_co_preadv,
+ .bdrv_co_pwritev = backup_top_co_pwritev,
+ .bdrv_co_pwrite_zeroes = backup_top_co_pwrite_zeroes,
+ .bdrv_co_pdiscard = backup_top_co_pdiscard,
+
+ .bdrv_getlength = backup_top_getlength,
+ .bdrv_child_perm = bdrv_filter_default_perms,
+ .bdrv_recurse_is_first_non_filter = backup_recurse_is_first_non_filter,
+ .bdrv_co_get_block_status = backup_co_get_block_status,
+
+ .is_filter = true,
+};
+
BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
BlockDriverState *target, int64_t speed,
MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
@@ -545,6 +682,7 @@ BlockJob *backup_job_create(const char *job_id,
BlockDriverState *bs,
int64_t len;
BlockDriverInfo bdi;
BackupBlockJob *job = NULL;
+ BlockDriverState *filter = NULL;
int ret;
assert(bs);
@@ -606,17 +744,33 @@ BlockJob *backup_job_create(const char *job_id,
BlockDriverState *bs,
bdrv_get_device_name(bs));
goto error;
}
+ /* Setup before write filter */
+ filter =
+ bdrv_new_open_driver(&backup_top,
+ NULL, bdrv_get_flags(bs), NULL, &error_abort);
+ filter->implicit = true;
+ filter->total_sectors = bs->total_sectors;
+ bdrv_set_aio_context(filter, bdrv_get_aio_context(bs));
+
+ /* Insert before write notifier in the BDS chain */
+ bdrv_ref(filter);
+ bdrv_drained_begin(bs);
+ bdrv_append_file(filter, bs, &error_abort);
+ bdrv_drained_end(bs);
/* job->common.len is fixed, so we can't allow resize */
- job = block_job_create(job_id, &backup_job_driver, bs,
+ job = block_job_create(job_id, &backup_job_driver, filter,
BLK_PERM_CONSISTENT_READ,
BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE |
BLK_PERM_WRITE_UNCHANGED | BLK_PERM_GRAPH_MOD,
speed, creation_flags, cb, opaque, errp);
+ bdrv_unref(filter);
if (!job) {
goto error;
}
+ job->filter = filter;
+
/* The target must match the source in size, so no resize here either */
job->target = blk_new(BLK_PERM_WRITE,
BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE |
@@ -675,6 +829,13 @@ BlockJob *backup_job_create(const char *job_id,
BlockDriverState *bs,
if (job) {
backup_clean(&job->common);
block_job_early_fail(&job->common);
+ } else {
+ /* don't leak filter if job creation failed */
+ if (filter) {
+ bdrv_child_try_set_perm(filter->file, 0, BLK_PERM_ALL,
+ &error_abort);
+ bdrv_replace_node(filter, bs, &error_abort);
+ }
}
return NULL;
diff --git a/block/io.c b/block/io.c
index 26003814eb..56aa67105a 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1332,7 +1332,7 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild
*child,
BlockDriverState *bs = child->bs;
BlockDriver *drv = bs->drv;
bool waited;
- int ret;
+ int ret = 0;
int64_t start_sector = offset >> BDRV_SECTOR_BITS;
int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
@@ -1359,9 +1359,7 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild
*child,
assert(child->perm & BLK_PERM_WRITE);
assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE);
- ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);
-
- if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
+ if (bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
!(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_pwrite_zeroes &&
qemu_iovec_is_zero(qiov)) {
flags |= BDRV_REQ_ZERO_WRITE;
@@ -1370,9 +1368,7 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild
*child,
}
}
- if (ret < 0) {
- /* Do nothing, write notifier decided to fail this request */
- } else if (flags & BDRV_REQ_ZERO_WRITE) {
+ if (flags & BDRV_REQ_ZERO_WRITE) {
bdrv_debug_event(bs, BLKDBG_PWRITEV_ZERO);
ret = bdrv_co_do_pwrite_zeroes(bs, offset, bytes, flags);
} else if (flags & BDRV_REQ_WRITE_COMPRESSED) {
diff --git a/block/mirror.c b/block/mirror.c
index e1a160e6ea..af7771e93a 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1174,11 +1174,11 @@ static void mirror_start_job(const char *job_id,
BlockDriverState *bs,
mirror_top_bs->total_sectors = bs->total_sectors;
bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
- /* bdrv_append takes ownership of the mirror_top_bs reference, need to keep
+ /* bdrv_append_backing() takes ownership of the mirror_top_bs reference,
need to keep
* it alive until block_job_create() succeeds even if bs has no parent. */
bdrv_ref(mirror_top_bs);
bdrv_drained_begin(bs);
- bdrv_append(mirror_top_bs, bs, &local_err);
+ bdrv_append_backing(mirror_top_bs, bs, &local_err);
bdrv_drained_end(bs);
if (local_err) {
diff --git a/blockdev.c b/blockdev.c
index 5c11c245b0..8e2fc6e64c 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1788,7 +1788,7 @@ static void external_snapshot_prepare(BlkActionState
*common,
* can fail, so we need to do it in .prepare; undoing it for abort is
* always possible. */
bdrv_ref(state->new_bs);
- bdrv_append(state->new_bs, state->old_bs, &local_err);
+ bdrv_append_backing(state->new_bs, state->old_bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
diff --git a/include/block/block.h b/include/block/block.h
index d1f03cb48b..744b50e734 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -244,8 +244,10 @@ int bdrv_create(BlockDriver *drv, const char* filename,
QemuOpts *opts, Error **errp);
int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp);
BlockDriverState *bdrv_new(void);
-void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
- Error **errp);
+void bdrv_append_file(BlockDriverState *bs_new, BlockDriverState *bs_top,
+ Error **errp);
+void bdrv_append_backing(BlockDriverState *bs_new, BlockDriverState *bs_top,
+ Error **errp);
void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
Error **errp);
@@ -256,6 +258,8 @@ BdrvChild *bdrv_open_child(const char *filename,
BlockDriverState* parent,
const BdrvChildRole *child_role,
bool allow_none, Error **errp);
+void bdrv_set_file(BlockDriverState *bs, BlockDriverState *file_bs,
+ Error **errp);
void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp);
int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
diff --git a/tests/qemu-iotests/141.out b/tests/qemu-iotests/141.out
index 82e763b68d..cc653c317a 100644
--- a/tests/qemu-iotests/141.out
+++ b/tests/qemu-iotests/141.out
@@ -9,7 +9,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
backing_file=TEST_DIR/m.
{"return": {}}
Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT size=1048576
backing_file=TEST_DIR/t.IMGFMT backing_fmt=IMGFMT
{"return": {}}
-{"error": {"class": "GenericError", "desc": "Node drv0 is in use"}}
+{"error": {"class": "GenericError", "desc": "Block device drv0 is in use"}}
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_CANCELLED", "data": {"device": "job0", "len": 1048576, "offset": 0,
"speed": 0, "type": "backup"}}
{"return": {}}
--
2.11.0