xref: /qemu/block/write-threshold.c (revision 4bda8224)
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-io.h"
15 #include "block/block_int.h"
16 #include "block/write-threshold.h"
17 #include "qapi/error.h"
18 #include "qapi/qapi-commands-block-core.h"
19 #include "qapi/qapi-events-block-core.h"
20 
21 uint64_t bdrv_write_threshold_get(const BlockDriverState *bs)
22 {
23     return bs->write_threshold_offset;
24 }
25 
26 void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes)
27 {
28     bs->write_threshold_offset = threshold_bytes;
29 }
30 
31 void qmp_block_set_write_threshold(const char *node_name,
32                                    uint64_t threshold_bytes,
33                                    Error **errp)
34 {
35     BlockDriverState *bs;
36 
37     bs = bdrv_find_node(node_name);
38     if (!bs) {
39         error_setg(errp, "Device '%s' not found", node_name);
40         return;
41     }
42 
43     bdrv_write_threshold_set(bs, threshold_bytes);
44 }
45 
46 void bdrv_write_threshold_check_write(BlockDriverState *bs, int64_t offset,
47                                       int64_t bytes)
48 {
49     int64_t end = offset + bytes;
50     uint64_t wtr = bs->write_threshold_offset;
51 
52     if (wtr > 0 && end > wtr) {
53         qapi_event_send_block_write_threshold(bs->node_name, end - wtr, wtr);
54 
55         /* autodisable to avoid flooding the monitor */
56         bdrv_write_threshold_set(bs, 0);
57     }
58 }
59