[Qemu-devel] [PATCH 16/17] vvfat: Implement .bdrv_co_preadv/pwritev interfaces

[Kevin Wolf]

This doesn't really convert any of the actual vvfat logic to use
vectored I/O (and it's doubtful whether that would make sense), but
instead just adapts the wrappers to the modern interface.

Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
 block/vvfat.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 46 insertions(+), 9 deletions(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index 6b85314..ad7c22a 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1177,6 +1177,7 @@ static int vvfat_open(BlockDriverState *bs, QDict 
*options, int flags,
         bs->read_only = 0;
     }
 
+    bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
     bs->total_sectors = cyls * heads * secs;
 
     if (init_directories(s, dirname, heads, secs, errp)) {
@@ -1419,14 +1420,31 @@ DLOG(fprintf(stderr, "sector %d not allocated\n", 
(int)sector_num));
     return 0;
 }
 
-static coroutine_fn int vvfat_co_read(BlockDriverState *bs, int64_t sector_num,
-                                      uint8_t *buf, int nb_sectors)
+static int coroutine_fn
+vvfat_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+                QEMUIOVector *qiov, int flags)
 {
     int ret;
     BDRVVVFATState *s = bs->opaque;
+    uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
+    int nb_sectors = bytes >> BDRV_SECTOR_BITS;
+    void *buf;
+
+    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
+    assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
+
+    buf = g_try_malloc(bytes);
+    if (bytes && buf == NULL) {
+        return -ENOMEM;
+    }
+
     qemu_co_mutex_lock(&s->lock);
     ret = vvfat_read(bs, sector_num, buf, nb_sectors);
     qemu_co_mutex_unlock(&s->lock);
+
+    qemu_iovec_from_buf(qiov, 0, buf, bytes);
+    g_free(buf);
+
     return ret;
 }
 
@@ -2873,14 +2891,31 @@ DLOG(checkpoint());
     return 0;
 }
 
-static coroutine_fn int vvfat_co_write(BlockDriverState *bs, int64_t 
sector_num,
-                                       const uint8_t *buf, int nb_sectors)
+static int coroutine_fn
+vvfat_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+                 QEMUIOVector *qiov, int flags)
 {
     int ret;
     BDRVVVFATState *s = bs->opaque;
+    uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
+    int nb_sectors = bytes >> BDRV_SECTOR_BITS;
+    void *buf;
+
+    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
+    assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
+
+    buf = g_try_malloc(bytes);
+    if (bytes && buf == NULL) {
+        return -ENOMEM;
+    }
+    qemu_iovec_to_buf(qiov, 0, buf, bytes);
+
     qemu_co_mutex_lock(&s->lock);
     ret = vvfat_write(bs, sector_num, buf, nb_sectors);
     qemu_co_mutex_unlock(&s->lock);
+
+    g_free(buf);
+
     return ret;
 }
 
@@ -2897,8 +2932,10 @@ static int64_t coroutine_fn 
vvfat_co_get_block_status(BlockDriverState *bs,
     return BDRV_BLOCK_DATA;
 }
 
-static int write_target_commit(BlockDriverState *bs, int64_t sector_num,
-       const uint8_t* buffer, int nb_sectors) {
+static int coroutine_fn
+write_target_commit(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+                    QEMUIOVector *qiov, int flags)
+{
     BDRVVVFATState* s = *((BDRVVVFATState**) bs->opaque);
     return try_commit(s);
 }
@@ -2911,7 +2948,7 @@ static void write_target_close(BlockDriverState *bs) {
 
 static BlockDriver vvfat_write_target = {
     .format_name        = "vvfat_write_target",
-    .bdrv_write         = write_target_commit,
+    .bdrv_co_pwritev    = write_target_commit,
     .bdrv_close         = write_target_close,
 };
 
@@ -3007,8 +3044,8 @@ static BlockDriver bdrv_vvfat = {
     .bdrv_file_open         = vvfat_open,
     .bdrv_close             = vvfat_close,
 
-    .bdrv_read              = vvfat_co_read,
-    .bdrv_write             = vvfat_co_write,
+    .bdrv_co_preadv         = vvfat_co_preadv,
+    .bdrv_co_pwritev        = vvfat_co_pwritev,
     .bdrv_co_get_block_status = vvfat_co_get_block_status,
 };
 
-- 
1.8.3.1