Re: [Qemu-devel] [PATCH v3 26/29] blkdebug: Make required alignment configurable

[Max Reitz]

On 17.01.2014 15:15, Kevin Wolf wrote:
The new 'align' option of blkdebug can be used in order to emulate
backends with a required 4k alignment on hosts which only really require
512 byte alignment.
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
  block/blkdebug.c | 16 ++++++++++++++++
  1 file changed, 16 insertions(+)

The patch itself is okay, but will have to be rebased on the 
blkdebug/blkverify series – specifically, we'll need to add this new 
option to qapi-schema.json (BlockdevOptionsBlkdebug).

diff --git a/block/blkdebug.c b/block/blkdebug.c
index ebc5f13..dc4ba46 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -346,6 +346,11 @@ static QemuOptsList runtime_opts = {
              .type = QEMU_OPT_STRING,
              .help = "[internal use only, will be removed]",
          },
+        {
+            .name = "align",
+            .type = QEMU_OPT_SIZE,
+            .help = "Required alignment in bytes",
+        },
          { /* end of list */ }
      },
  };
@@ -357,6 +362,7 @@ static int blkdebug_open(BlockDriverState *bs, QDict 
*options, int flags,
      QemuOpts *opts;
      Error *local_err = NULL;
      const char *filename, *config;
+    uint64_t align;
      int ret;
  
      opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
@@ -394,6 +400,16 @@ static int blkdebug_open(BlockDriverState *bs, QDict 
*options, int flags,
          goto fail;
      }
  
+    /* Set request alignment */
+    align = qemu_opt_get_size(opts, "align", bs->request_alignment);
+    if (align > 0 && align < INT_MAX && !(align & (align - 1))) {

Hm, I like that test to check whether align is a power of two. ;-)

Max

+        bs->request_alignment = align;
+    } else {
+        error_setg(errp, "Invalid alignment");
+        ret = -EINVAL;
+        goto fail;
+    }
+
      ret = 0;
  fail:
      qemu_opts_del(opts);