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[Qemu-devel] [PULL 03/20] block: add bdrv_add_before_write_notifier()
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PULL 03/20] block: add bdrv_add_before_write_notifier() |
Date: |
Fri, 28 Jun 2013 16:24:52 +0200 |
From: Stefan Hajnoczi <address@hidden>
The bdrv_add_before_write_notifier() function installs a callback that
is invoked before a write request is processed. This will be used to
implement copy-on-write point-in-time snapshots where we need to copy
out old data before overwriting it.
Note that BdrvTrackedRequest is moved to block_int.h since it is passed
to .notify() functions.
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Kevin Wolf <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
block.c | 23 ++++++++++++-----------
include/block/block_int.h | 23 ++++++++++++++++++++++-
2 files changed, 34 insertions(+), 12 deletions(-)
diff --git a/block.c b/block.c
index 8e77d46..0898f6b 100644
--- a/block.c
+++ b/block.c
@@ -305,6 +305,7 @@ BlockDriverState *bdrv_new(const char *device_name)
}
bdrv_iostatus_disable(bs);
notifier_list_init(&bs->close_notifiers);
+ notifier_with_return_list_init(&bs->before_write_notifiers);
return bs;
}
@@ -1840,16 +1841,6 @@ int bdrv_commit_all(void)
return 0;
}
-struct BdrvTrackedRequest {
- BlockDriverState *bs;
- int64_t sector_num;
- int nb_sectors;
- bool is_write;
- QLIST_ENTRY(BdrvTrackedRequest) list;
- Coroutine *co; /* owner, used for deadlock detection */
- CoQueue wait_queue; /* coroutines blocked on this request */
-};
-
/**
* Remove an active request from the tracked requests list
*
@@ -2620,7 +2611,11 @@ static int coroutine_fn
bdrv_co_do_writev(BlockDriverState *bs,
tracked_request_begin(&req, bs, sector_num, nb_sectors, true);
- if (flags & BDRV_REQ_ZERO_WRITE) {
+ ret = notifier_with_return_list_notify(&bs->before_write_notifiers, &req);
+
+ if (ret < 0) {
+ /* Do nothing, write notifier decided to fail this request */
+ } else if (flags & BDRV_REQ_ZERO_WRITE) {
ret = bdrv_co_do_write_zeroes(bs, sector_num, nb_sectors);
} else {
ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
@@ -4581,3 +4576,9 @@ AioContext *bdrv_get_aio_context(BlockDriverState *bs)
/* Currently BlockDriverState always uses the main loop AioContext */
return qemu_get_aio_context();
}
+
+void bdrv_add_before_write_notifier(BlockDriverState *bs,
+ NotifierWithReturn *notifier)
+{
+ notifier_with_return_list_add(&bs->before_write_notifiers, notifier);
+}
diff --git a/include/block/block_int.h b/include/block/block_int.h
index ba52247..2d00955 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -59,7 +59,16 @@
#define BLOCK_OPT_LAZY_REFCOUNTS "lazy_refcounts"
#define BLOCK_OPT_ADAPTER_TYPE "adapter_type"
-typedef struct BdrvTrackedRequest BdrvTrackedRequest;
+typedef struct BdrvTrackedRequest {
+ BlockDriverState *bs;
+ int64_t sector_num;
+ int nb_sectors;
+ bool is_write;
+ QLIST_ENTRY(BdrvTrackedRequest) list;
+ Coroutine *co; /* owner, used for deadlock detection */
+ CoQueue wait_queue; /* coroutines blocked on this request */
+} BdrvTrackedRequest;
+
typedef struct BlockIOLimit {
int64_t bps[3];
@@ -248,6 +257,9 @@ struct BlockDriverState {
NotifierList close_notifiers;
+ /* Callback before write request is processed */
+ NotifierWithReturnList before_write_notifiers;
+
/* number of in-flight copy-on-read requests */
unsigned int copy_on_read_in_flight;
@@ -299,6 +311,15 @@ void bdrv_set_io_limits(BlockDriverState *bs,
BlockIOLimit *io_limits);
/**
+ * bdrv_add_before_write_notifier:
+ *
+ * Register a callback that is invoked before write requests are processed but
+ * after any throttling or waiting for overlapping requests.
+ */
+void bdrv_add_before_write_notifier(BlockDriverState *bs,
+ NotifierWithReturn *notifier);
+
+/**
* bdrv_get_aio_context:
*
* Returns: the currently bound #AioContext
--
1.8.1.4
- [Qemu-devel] [PULL 00/20] Block patches, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 01/20] raw-posix: Fix /dev/cdrom magic on OS X, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 02/20] notify: add NotiferWithReturn so notifier list can abort, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 03/20] block: add bdrv_add_before_write_notifier(),
Kevin Wolf <=
- [Qemu-devel] [PULL 06/20] blockdev: use bdrv_getlength() in qmp_drive_mirror(), Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 04/20] block: add basic backup support to block driver, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 05/20] blockdev: drop redundant proto_drv check, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 09/20] blockdev: allow BdrvActionOps->commit() to be NULL, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 07/20] block: add drive-backup QMP command, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 10/20] blockdev: add DriveBackup transaction, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 08/20] blockdev: rename BlkTransactionStates to singular, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 11/20] blockdev: add Abort transaction, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 12/20] qemu-iotests: extract wait_until_completed() into iotests.py, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 15/20] block/ssh: Set bdrv_has_zero_init according to the file type., Kevin Wolf, 2013/06/28