qemu

FORK: QEMU emulator
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write-threshold.c (1699B)

      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 "block/write-threshold.h"
     16 #include "qapi/error.h"
     17 #include "qapi/qapi-commands-block-core.h"
     18 #include "qapi/qapi-events-block-core.h"
     19 
     20 uint64_t bdrv_write_threshold_get(const BlockDriverState *bs)
     21 {
     22     return bs->write_threshold_offset;
     23 }
     24 
     25 void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes)
     26 {
     27     bs->write_threshold_offset = threshold_bytes;
     28 }
     29 
     30 void qmp_block_set_write_threshold(const char *node_name,
     31                                    uint64_t threshold_bytes,
     32                                    Error **errp)
     33 {
     34     BlockDriverState *bs;
     35     AioContext *aio_context;
     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     aio_context = bdrv_get_aio_context(bs);
     44     aio_context_acquire(aio_context);
     45 
     46     bdrv_write_threshold_set(bs, threshold_bytes);
     47 
     48     aio_context_release(aio_context);
     49 }
     50 
     51 void bdrv_write_threshold_check_write(BlockDriverState *bs, int64_t offset,
     52                                       int64_t bytes)
     53 {
     54     int64_t end = offset + bytes;
     55     uint64_t wtr = bs->write_threshold_offset;
     56 
     57     if (wtr > 0 && end > wtr) {
     58         qapi_event_send_block_write_threshold(bs->node_name, end - wtr, wtr);
     59 
     60         /* autodisable to avoid flooding the monitor */
     61         bdrv_write_threshold_set(bs, 0);
     62     }
     63 }