[PATCH 3/6] sysemu/block-backend: Document blk_read()/blk_pwrite()

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

The blk_read()/blk_pwrite() return value is not obvious,
document it.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/sysemu/block-backend.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index f2dcf63ae3..823b8e94a7 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -153,7 +153,31 @@ BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
                                   int bytes, BdrvRequestFlags flags,
                                   BlockCompletionFunc *cb, void *opaque);
 int blk_make_zero(BlockBackend *blk, BdrvRequestFlags flags);
+
+/**
+ * blk_pread:
+ *
+ * @blk - the block backend where the buffer content is going to be read from
+ * @offset: position in bytes to read at
+ * @buf: the data buffer
+ * @bytes: number of bytes to read
+ *
+ * Returns: the number of bytes read on success, or a negative errno otherwise.
+ */
 int blk_pread(BlockBackend *blk, int64_t offset, void *buf, int bytes);
+
+/**
+ * blk_pwrite:
+ *
+ * @blk - the block backend where the buffer content is going to be written to
+ * @offset: position in bytes to write at
+ * @buf: the data buffer
+ * @bytes: number of bytes of @buf to write
+ * @flags: request flags
+ *
+ * Returns: the number of bytes consumed on success,
+ *          or a negative errno otherwise.
+ */
 int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int bytes,
                BdrvRequestFlags flags);
 int64_t blk_getlength(BlockBackend *blk);
-- 
2.21.3