Regular block devices (/dev/sda*, /dev/nvme*, etc) interface is not limited
by the underlying storage limits, but rather the kernel block layer
takes care to split the requests that are too large/fragmented.
Doing so allows us to have less overhead in qemu.
Signed-off-by: Maxim Levitsky <mlevi...@redhat.com>
---
block/file-posix.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index ab05b51a66..66dad34f8a 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1038,15 +1038,13 @@ static void raw_reopen_abort(BDRVReopenState *state)
s->reopen_state = NULL;
}
-static int hdev_get_max_transfer_length(BlockDriverState *bs, int fd)
+static int sg_get_max_transfer_length(BlockDriverState *bs, int fd)
{
#ifdef BLKSECTGET
int max_bytes = 0;
- short max_sectors = 0;
- if (bs->sg && ioctl(fd, BLKSECTGET, &max_bytes) == 0) {
+
+ if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) {
return max_bytes;
- } else if (!bs->sg && ioctl(fd, BLKSECTGET, &max_sectors) == 0) {
- return max_sectors << BDRV_SECTOR_BITS;
} else {
return -errno;
}
@@ -1055,7 +1053,7 @@ static int hdev_get_max_transfer_length(BlockDriverState
*bs, int fd)
#endif
}
-static int hdev_get_max_segments(const struct stat *st)
+static int sg_get_max_segments(const struct stat *st)
{
#ifdef CONFIG_LINUX
char buf[32];
@@ -1106,12 +1104,12 @@ static void raw_refresh_limits(BlockDriverState *bs,
Error **errp)
struct stat st;
if (!fstat(s->fd, &st)) {
- if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode)) {
- int ret = hdev_get_max_transfer_length(bs, s->fd);
+ if (bs->sg) {
+ int ret = sg_get_max_transfer_length(bs, s->fd);
if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) {
bs->bl.max_transfer = pow2floor(ret);
}
- ret = hdev_get_max_segments(&st);
+ ret = sg_get_max_segments(&st);
if (ret > 0) {
bs->bl.max_transfer = MIN(bs->bl.max_transfer,
ret * getpagesize());
--
2.17.2
