[Qemu-devel] [PATCH 3/7] raw: support discard on block devices

[Paolo Bonzini <pbonzini@redhat.com>]

Block devices use a ioctl instead of fallocate, so add a separate
implementation.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/raw-posix.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index b647cfb..1d32139 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1345,6 +1345,40 @@ static BlockDriverAIOCB *hdev_aio_ioctl(BlockDriverState *bs,
     return thread_pool_submit_aio(aio_worker, acb, cb, opaque);
 }
 
+static coroutine_fn int hdev_co_discard(BlockDriverState *bs,
+    int64_t sector_num, int nb_sectors)
+{
+    BDRVRawState *s = bs->opaque;
+    int ret;
+
+    if (s->has_discard == 0) {
+        return 0;
+    }
+    ret = fd_open(bs);
+    if (ret < 0) {
+        return ret;
+    }
+
+    ret = -EOPNOTSUPP;
+#ifdef BLKDISCARD
+    do {
+        uint64_t range[2] = { sector_num * 512, (uint64_t)nb_sectors * 512 };
+        if (ioctl(s->fd, BLKDISCARD, range) == 0) {
+            return 0;
+        }
+    } while (errno == EINTR);
+
+    ret = -errno;
+#endif
+    if (ret == -ENODEV || ret == -ENOSYS || ret == -EOPNOTSUPP ||
+        ret == -ENOTTY) {
+        s->has_discard = 0;
+        ret = 0;
+    }
+    return ret;
+
+}
+
 #elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 static int fd_open(BlockDriverState *bs)
 {
@@ -1413,6 +1447,8 @@ static BlockDriver bdrv_host_device = {
     .create_options     = raw_create_options,
     .bdrv_has_zero_init = hdev_has_zero_init,
 
+    .bdrv_co_discard    = hdev_co_discard,
+
     .bdrv_aio_readv	= raw_aio_readv,
     .bdrv_aio_writev	= raw_aio_writev,
     .bdrv_aio_flush	= raw_aio_flush,
-- 
1.8.1