Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Block pull request

# gpg: Signature made Wed 28 May 2014 13:31:15 BST using RSA key ID 81AB73C8
# gpg: Can't check signature: public key not found

* remotes/stefanha/tags/block-pull-request: (33 commits)
  block/sheepdog: Don't use qerror_report()
  block/sheepdog: Fix silent sd_open(), sd_create() failures
  block/sheepdog: Propagate errors to open and create methods
  block/sheepdog: Propagate errors through find_vdi_name()
  block/sheepdog: Propagate errors through do_sd_create()
  block/sheepdog: Propagate errors through sd_prealloc()
  block/sheepdog: Propagate errors through get_sheep_fd()
  block/sheepdog: Propagate errors through connect_to_sdog()
  block/vvfat: Propagate errors through init_directories()
  block/vvfat: Propagate errors through enable_write_target()
  block/ssh: Propagate errors to open and create methods
  block/ssh: Propagate errors through connect_to_ssh()
  block/ssh: Propagate errors through authenticate()
  block/ssh: Propagate errors through check_host_key()
  block/ssh: Drop superfluous libssh2_session_last_errno() calls
  block/rbd: Propagate errors to open and create methods
  qemu-nbd: Don't use qerror_report()
  blockdev: Don't use qerror_report() in do_drive_del()
  blockdev: Don't use qerror_report_err() in drive_init()
  docs: Define refcount_bits value
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>