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e2462113 FR |
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 | ||
80c71a24 | 13 | #include "qemu/osdep.h" |
e2462113 | 14 | #include "block/block_int.h" |
10817bf0 | 15 | #include "qemu/coroutine.h" |
e2462113 FR |
16 | #include "block/write-threshold.h" |
17 | #include "qemu/notify.h" | |
18 | #include "qapi-event.h" | |
19 | #include "qmp-commands.h" | |
20 | ||
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 | &error_abort); | |
68 | ||
69 | /* autodisable to avoid flooding the monitor */ | |
70 | write_threshold_disable(bs); | |
71 | } | |
72 | ||
73 | return 0; /* should always let other notifiers run */ | |
74 | } | |
75 | ||
76 | static void write_threshold_register_notifier(BlockDriverState *bs) | |
77 | { | |
78 | bs->write_threshold_notifier.notify = before_write_notify; | |
79 | notifier_with_return_list_add(&bs->before_write_notifiers, | |
80 | &bs->write_threshold_notifier); | |
81 | } | |
82 | ||
83 | static void write_threshold_update(BlockDriverState *bs, | |
84 | int64_t threshold_bytes) | |
85 | { | |
86 | bs->write_threshold_offset = threshold_bytes; | |
87 | } | |
88 | ||
89 | void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes) | |
90 | { | |
91 | if (bdrv_write_threshold_is_set(bs)) { | |
92 | if (threshold_bytes > 0) { | |
93 | write_threshold_update(bs, threshold_bytes); | |
94 | } else { | |
95 | write_threshold_disable(bs); | |
96 | } | |
97 | } else { | |
98 | if (threshold_bytes > 0) { | |
99 | /* avoid multiple registration */ | |
100 | write_threshold_register_notifier(bs); | |
101 | write_threshold_update(bs, threshold_bytes); | |
102 | } | |
103 | /* discard bogus disable request */ | |
104 | } | |
105 | } | |
106 | ||
107 | void qmp_block_set_write_threshold(const char *node_name, | |
108 | uint64_t threshold_bytes, | |
109 | Error **errp) | |
110 | { | |
111 | BlockDriverState *bs; | |
112 | AioContext *aio_context; | |
113 | ||
114 | bs = bdrv_find_node(node_name); | |
115 | if (!bs) { | |
6ec46ad5 | 116 | error_setg(errp, "Device '%s' not found", node_name); |
e2462113 FR |
117 | return; |
118 | } | |
119 | ||
120 | aio_context = bdrv_get_aio_context(bs); | |
121 | aio_context_acquire(aio_context); | |
122 | ||
123 | bdrv_write_threshold_set(bs, threshold_bytes); | |
124 | ||
125 | aio_context_release(aio_context); | |
126 | } |