[Qemu-devel] [V3 0/3]block: Dynamically change hostcache setting using new "block_set" command

[Supriya Kannery]

  Currently host page cache setting for a block device cannot be changed
without restarting a running VM. Following patchset [V3] is for enabling
dynamic change of hostcache setting for block devices through qemu monitor
and QMP. Code changes are based on patches from Christoph Hellwig and 
Prerna Saxena.

Changes from patchset V2:
1. Command "block_set" added for changing block device params dynamically
2. Enhanced info-block to display hostcache setting of block device
3. Added qmp interfaces for setting and querying hostcache

New block command added:
"block_set" 
    -- Sets block device parameters while guest is running.

Usage:
 block_set <device> <param> <value> 
   <device> = block device
   <param>  = parameter (say, "hostcache")
   <value>  = on/off

 1/3 Enhance "info block" to display hostcache setting
 2/3 New error classes for file reopen and device insertion
 3/3 Command "block_set" for dynamic params change for block device

 qemu/block.c         |   62 +++++++++++++++++++++++++++++++++++++++++
                             +++++++++----
 qemu/block.h         |    2 ++
 qemu/blockdev.c      |   32 ++++++++++++++++++++++++++++++++
 qemu/blockdev.h      |    1 +
 qemu/hmp-commands.hx |   15 +++++++++++++++
 qemu/qerror.c        |    8 ++++++++
 qemu/qerror.h        |    6 ++++++
 qemu/qmp-commands.hx |    2 ++
 qmp-commands.hx      |   30 +++++++++++++++++++++++++++++-
 9 files changed, 153 insertions(+), 5 deletions(-)
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