Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging
[qemu.git] / block / write-threshold.c
1 /*
2 * QEMU System Emulator block write threshold notification
3 *
4 * Copyright Red Hat, Inc. 2014
5 *
6 * Authors:
7 * Francesco Romani <fromani@redhat.com>
8 *
9 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
10 * See the COPYING.LIB file in the top-level directory.
11 */
12
13 #include "qemu/osdep.h"
14 #include "block/block_int.h"
15 #include "qemu/coroutine.h"
16 #include "block/write-threshold.h"
17 #include "qemu/notify.h"
18 #include "qapi/error.h"
19 #include "qapi/qapi-commands-block-core.h"
20 #include "qapi/qapi-events-block-core.h"
21
22 uint64_t bdrv_write_threshold_get(const BlockDriverState *bs)
23 {
24 return bs->write_threshold_offset;
25 }
26
27 bool bdrv_write_threshold_is_set(const BlockDriverState *bs)
28 {
29 return bs->write_threshold_offset > 0;
30 }
31
32 static void write_threshold_disable(BlockDriverState *bs)
33 {
34 if (bdrv_write_threshold_is_set(bs)) {
35 notifier_with_return_remove(&bs->write_threshold_notifier);
36 bs->write_threshold_offset = 0;
37 }
38 }
39
40 uint64_t bdrv_write_threshold_exceeded(const BlockDriverState *bs,
41 const BdrvTrackedRequest *req)
42 {
43 if (bdrv_write_threshold_is_set(bs)) {
44 if (req->offset > bs->write_threshold_offset) {
45 return (req->offset - bs->write_threshold_offset) + req->bytes;
46 }
47 if ((req->offset + req->bytes) > bs->write_threshold_offset) {
48 return (req->offset + req->bytes) - bs->write_threshold_offset;
49 }
50 }
51 return 0;
52 }
53
54 static int coroutine_fn before_write_notify(NotifierWithReturn *notifier,
55 void *opaque)
56 {
57 BdrvTrackedRequest *req = opaque;
58 BlockDriverState *bs = req->bs;
59 uint64_t amount = 0;
60
61 amount = bdrv_write_threshold_exceeded(bs, req);
62 if (amount > 0) {
63 qapi_event_send_block_write_threshold(
64 bs->node_name,
65 amount,
66 bs->write_threshold_offset);
67
68 /* autodisable to avoid flooding the monitor */
69 write_threshold_disable(bs);
70 }
71
72 return 0; /* should always let other notifiers run */
73 }
74
75 static void write_threshold_register_notifier(BlockDriverState *bs)
76 {
77 bs->write_threshold_notifier.notify = before_write_notify;
78 bdrv_add_before_write_notifier(bs, &bs->write_threshold_notifier);
79 }
80
81 static void write_threshold_update(BlockDriverState *bs,
82 int64_t threshold_bytes)
83 {
84 bs->write_threshold_offset = threshold_bytes;
85 }
86
87 void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes)
88 {
89 if (bdrv_write_threshold_is_set(bs)) {
90 if (threshold_bytes > 0) {
91 write_threshold_update(bs, threshold_bytes);
92 } else {
93 write_threshold_disable(bs);
94 }
95 } else {
96 if (threshold_bytes > 0) {
97 /* avoid multiple registration */
98 write_threshold_register_notifier(bs);
99 write_threshold_update(bs, threshold_bytes);
100 }
101 /* discard bogus disable request */
102 }
103 }
104
105 void qmp_block_set_write_threshold(const char *node_name,
106 uint64_t threshold_bytes,
107 Error **errp)
108 {
109 BlockDriverState *bs;
110 AioContext *aio_context;
111
112 bs = bdrv_find_node(node_name);
113 if (!bs) {
114 error_setg(errp, "Device '%s' not found", node_name);
115 return;
116 }
117
118 aio_context = bdrv_get_aio_context(bs);
119 aio_context_acquire(aio_context);
120
121 bdrv_write_threshold_set(bs, threshold_bytes);
122
123 aio_context_release(aio_context);
124 }