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

# gpg: Signature made Tue 05 Sep 2017 14:28:52 BST
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  block: document semantics of bdrv_co_preadv|pwritev
  qemu-iotests: use context managers for resource cleanup in 194
  iotests.py: add FilePath context manager
  qemu.py: make VM() a context manager

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

1 files changed, 31 insertions, 0 deletions

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 7571c0aaaf..7816b43a27 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -146,12 +146,43 @@ struct BlockDriver {
 
     int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
+
+    /**
+     * @offset: position in bytes to read at
+     * @bytes: number of bytes to read
+     * @qiov: the buffers to fill with read data
+     * @flags: currently unused, always 0
+     *
+     * @offset and @bytes will be a multiple of 'request_alignment',
+     * but the length of individual @qiov elements does not have to
+     * be a multiple.
+     *
+     * @bytes will always equal the total size of @qiov, and will be
+     * no larger than 'max_transfer'.
+     *
+     * The buffer in @qiov may point directly to guest memory.
+     */
     int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs,
         uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
     int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
     int coroutine_fn (*bdrv_co_writev_flags)(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags);
+    /**
+     * @offset: position in bytes to write at
+     * @bytes: number of bytes to write
+     * @qiov: the buffers containing data to write
+     * @flags: zero or more bits allowed by 'supported_write_flags'
+     *
+     * @offset and @bytes will be a multiple of 'request_alignment',
+     * but the length of individual @qiov elements does not have to
+     * be a multiple.
+     *
+     * @bytes will always equal the total size of @qiov, and will be
+     * no larger than 'max_transfer'.
+     *
+     * The buffer in @qiov may point directly to guest memory.
+     */
     int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs,
         uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);