Francesco Romani | e246211 | 2015-01-12 14:11:13 +0100 | [diff] [blame] | 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 | |
Peter Maydell | 80c71a2 | 2016-01-18 18:01:42 +0000 | [diff] [blame] | 13 | #include "qemu/osdep.h" |
Francesco Romani | e246211 | 2015-01-12 14:11:13 +0100 | [diff] [blame] | 14 | #include "block/block_int.h" |
Daniel P. Berrange | 10817bf | 2015-09-01 14:48:02 +0100 | [diff] [blame] | 15 | #include "qemu/coroutine.h" |
Francesco Romani | e246211 | 2015-01-12 14:11:13 +0100 | [diff] [blame] | 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) { |
Markus Armbruster | 6ec46ad | 2015-03-13 18:51:38 +0100 | [diff] [blame] | 116 | error_setg(errp, "Device '%s' not found", node_name); |
Francesco Romani | e246211 | 2015-01-12 14:11:13 +0100 | [diff] [blame] | 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 | } |