[v2,07/17] cloop: Implement .bdrv_co_preadv() interface

Commit Message

Kevin Wolf April 28, 2016, 1:16 p.m. UTC

Signed-off-by: Kevin Wolf <[e-mail]>
---
 block/cloop.c | 38 ++++++++++++++++++++++----------------
 1 file changed, 22 insertions(+), 16 deletions(-)

Comments

Eric Blake April 29, 2016, 2:28 a.m. UTC | #1

On 04/28/2016 07:16 AM, Kevin Wolf wrote:
> Signed-off-by: Kevin Wolf <[e-mail]>
> ---
>  block/cloop.c | 38 ++++++++++++++++++++++----------------
>  1 file changed, 22 insertions(+), 16 deletions(-)
> 

>      for (i = 0; i < nb_sectors; i++) {
> +        void *data;
>          uint32_t sector_offset_in_block =
>              ((sector_num + i) % s->sectors_per_block),
>              block_num = (sector_num + i) / s->sectors_per_block;
>          if (cloop_read_block(bs, block_num) != 0) {
> -            return -1;
> +            ret = -EIO;
> +            goto fail;

Might want to mention in the commit message that the fix of the return
value to use negative errno is intentional.

Otherwise,
Reviewed-by: Eric Blake <[e-mail]>

Patch

diff --git a/block/cloop.c b/block/cloop.c
index a84f140..fc1ca3a 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -66,6 +66,7 @@  static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
 
     bs->read_only = 1;
+    bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
 
     /* read header */
     ret = bdrv_pread(bs->file->bs, 128, &s->block_size, 4);
@@ -229,33 +230,38 @@  static inline int cloop_read_block(BlockDriverState *bs, int block_num)
     return 0;
 }
 
-static int cloop_read(BlockDriverState *bs, int64_t sector_num,
-                    uint8_t *buf, int nb_sectors)
+static int coroutine_fn
+cloop_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+                QEMUIOVector *qiov, int flags)
 {
     BDRVCloopState *s = bs->opaque;
-    int i;
+    uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
+    int nb_sectors = bytes >> BDRV_SECTOR_BITS;
+    int ret, i;
+
+    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
+    assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
+
+    qemu_co_mutex_lock(&s->lock);
 
     for (i = 0; i < nb_sectors; i++) {
+        void *data;
         uint32_t sector_offset_in_block =
             ((sector_num + i) % s->sectors_per_block),
             block_num = (sector_num + i) / s->sectors_per_block;
         if (cloop_read_block(bs, block_num) != 0) {
-            return -1;
+            ret = -EIO;
+            goto fail;
         }
-        memcpy(buf + i * 512,
-            s->uncompressed_block + sector_offset_in_block * 512, 512);
+
+        data = s->uncompressed_block + sector_offset_in_block * 512;
+        qemu_iovec_from_buf(qiov, i * 512, data, 512);
     }
-    return 0;
-}
 
-static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num,
-                                      uint8_t *buf, int nb_sectors)
-{
-    int ret;
-    BDRVCloopState *s = bs->opaque;
-    qemu_co_mutex_lock(&s->lock);
-    ret = cloop_read(bs, sector_num, buf, nb_sectors);
+    ret = 0;
+fail:
     qemu_co_mutex_unlock(&s->lock);
+
     return ret;
 }
 
@@ -273,7 +279,7 @@  static BlockDriver bdrv_cloop = {
     .instance_size  = sizeof(BDRVCloopState),
     .bdrv_probe     = cloop_probe,
     .bdrv_open      = cloop_open,
-    .bdrv_read      = cloop_co_read,
+    .bdrv_co_preadv = cloop_co_preadv,
     .bdrv_close     = cloop_close,
 };