[Qemu-devel] [RFC v2 0/6] block: Error parameter for opening/creating images

[Max Reitz]

This RFC adds an Error ** parameter to bdrv_open, bdrv_file_open,
bdrv_create and the respective functions provided by a block driver.

This results in more specific error information than just -errno provided
to the user when opening or creating images (disregarding the fact that
block drivers often already use error_report, which is generally changed
to error_setg through this patch).

The fifth patch in this series changes the qcow2 block driver to set an
example of usage in a block driver.

Note that several I/O tests break by applying this RFC since they expect
different error messages (generally, previously, an error message on
image opening/creation consisted of two lines; the first of which would be
generated by the driver through error_report, the second by the block
layer itself through strerror(-ret); this patch is designed to merge these
two lines into a single one). This applies to the tests 49, 51, 54 and 60.

v2:
 - included all block drivers
 - split open/create patches (old 1 into 1/2 and old 2 into 3/4)
 - added a patch (6) for printing out error messages from blk_open,
   blk_file_open and blk_create in all block drivers (except qcow2, for
   which there is a dedicated patch (5))
   I intentionally made this an own commit since I think this to be
   real functionality, whereas the patches 3 and 4 are more for
   introducing Error into block.c and making sure everything compiles
   with these changes (without actually adding functionality to any
   other code). However, I'm well aware that this in some way breaks
   the code between patches 3/4 and 6, since some error messages may be
   discarded between these commits. Therefore I wouldn't object too much
   to merging patch 6 with 3/4.

Max Reitz (6):
  bdrv: Use "Error" for opening images
  bdrv: Use "Error" for creating images
  block: Error parameter for open functions
  block: Error parameter for create functions
  qcow2: Use Error parameter
  bdrv: No silent error message discarding

 block.c                   | 164 ++++++++++++++++++++++++++++++----------------
 block/blkdebug.c          |   7 +-
 block/blkverify.c         |  11 +++-
 block/bochs.c             |   3 +-
 block/cloop.c             |   3 +-
 block/cow.c               |  15 +++--
 block/curl.c              |   3 +-
 block/dmg.c               |   3 +-
 block/gluster.c           |   4 +-
 block/iscsi.c             |   6 +-
 block/mirror.c            |   5 +-
 block/nbd.c               |   3 +-
 block/parallels.c         |   3 +-
 block/qcow.c              |  15 +++--
 block/qcow2.c             | 143 ++++++++++++++++++++++++++--------------
 block/qed.c               |  18 +++--
 block/raw-posix.c         |  18 +++--
 block/raw-win32.c         |   9 ++-
 block/raw_bsd.c           |  16 ++++-
 block/rbd.c               |   6 +-
 block/sheepdog.c          |  14 ++--
 block/snapshot.c          |   2 +-
 block/ssh.c               |   6 +-
 block/vdi.c               |   6 +-
 block/vhdx.c              |   3 +-
 block/vmdk.c              |  17 +++--
 block/vpc.c               |   6 +-
 block/vvfat.c             |  13 +++-
 blockdev.c                |  30 ++++-----
 include/block/block.h     |  11 ++--
 include/block/block_int.h |   9 ++-
 qemu-img.c                |  39 +++++------
 qemu-io.c                 |  14 ++--
 qemu-nbd.c                |   6 +-
 34 files changed, 410 insertions(+), 221 deletions(-)

-- 
1.8.3.1