[Qemu-devel] [v9 Patch 0/6]Qemu: Host pagecache setting from cmdline and monitor

[Supriya Kannery]

Following patchset is for enabling dynamic change of
host pagecache setting of block devices through qemu 
monitor. 

This patchset introduces 
a. monitor command 'block_set_hostcache' using which host 
   pagecache setting for a block device can be changed 
   dynamically. 
b. a new option for setting host cache from qemu
   commandline option -drive  "hostcache=on/off".
c. BDRVReopenState, a generic structure which can be 
   extended by each of the block drivers to reopen 
   respective image files.
   Extension of this structure for drivers raw-posix 
   is done here.
   Note: 'hostcache and 'cache' options when used together,
   cache=xx will override hostcache=yy.

v9:
 1. Rebased patchset to use qapi interfaces
 2. Approach of extending BDRVReopenState changed
    to use container_of()

v8:
 1. Mandate implementation of all three reopen 
    related functions by block drivers.
 2. If 'cache=xx' and 'hostcache=yy' specified
    in cmdline, 'cache=' overrides 'hostcache='.
    
v7:
 1. Added structure BDRVReopenState to support safe 
    reopening of image files.
 2. Implemented reopen functions for raw-posix driver

v6:
 1. "block_set_hostcache" to replace "block_set" command

v5:
 1. Defined qerror class for incorrect command syntax.
 2. Changed error_report() calls to qerror_report()

v4:
    Added 'hostcache' option to '-drive' commandline option.

v3:
  1. Command "block_set" for changing various block params
  2. Enhanced info-block to display hostcache setting 
  3. Added qmp interfaces for setting and querying hostcache

v2:
  1. Support of dynamic cache change only for hostcache.
  2. Monitor command "hostcache_get" added to display cache setting
  3. Backed off the changes for display of cache setting in "info block"

v1:
     Dynamic cache change through monitor

New block command added:
"block_set_hostcache"
    -- Sets hostcache parameter for block device  while guest is running.

Usage:
 block_set_hostcache  <device> <option>
   <device> = block device
   <option>  = on/off


New 'hostcache' option added to -drive:
 -drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
        ....
"       [,readonly=on|off][,hostcache=on|off]\n"

 qemu/block.c           |  111 
+++++++++++++++++++++++++++++++++++++++++++++---- 
 qemu/block.h           |    5 +  
 qemu/block/raw-posix.c |   72 ++++++++++++++++++++++++++++++++
 qemu/block/raw.c       |   23 +++++++++-
 qemu/block_int.h       |   13 +++++
 qemu/blockdev.c        |   33 ++++++++++++++
 qemu/blockdev.h        |    2
 qemu/hmp-commands.hx   |   14 ++++++
 qemu/hmp.c             |    2
 qemu/qapi-schema.json  |    4 +
 qemu/qapi-types.h      |    1
 qemu/qemu-common.h     |    1
 qemu/qemu-config.c     |    4 +
 qemu/qemu-options.hx   |    2
 qemu/qerror.c          |    8 +++
 qemu/qerror.h          |    6 ++
 qemu/qmp-commands.hx   |   27 ++++++++++++
 20 files changed, 315 insertions(+), 13 deletions(-)

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