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-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     AioContext *aio_context;
  37
  38     bs = bdrv_find_node(node_name);
  39     if (!bs) {
  40         error_setg(errp, "Device '%s' not found", node_name);
  41         return;
  42     }
  43
  44     aio_context = bdrv_get_aio_context(bs);
  45     aio_context_acquire(aio_context);
  46
  47     bdrv_write_threshold_set(bs, threshold_bytes);
  48
  49     aio_context_release(aio_context);
  50 }
  51
  52 void bdrv_write_threshold_check_write(BlockDriverState *bs, int64_t offset,
  53                                       int64_t bytes)
  54 {
  55     int64_t end = offset + bytes;
  56     uint64_t wtr = bs->write_threshold_offset;
  57
  58     if (wtr > 0 && end > wtr) {
  59         qapi_event_send_block_write_threshold(bs->node_name, end - wtr, wtr);
  60
  61         /* autodisable to avoid flooding the monitor */
  62         bdrv_write_threshold_set(bs, 0);
  63     }
  64 }