To debug this I added this temporary patch:
diff --git a/block/gluster.c b/block/gluster.c
index d2d187490b..790ef4251b 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -912,6 +912,7 @@ out:
static bool gluster_is_io_aligned(struct glfs_fd *fd, void *buf, size_t len)
{
ssize_t ret = glfs_pread(fd, buf, len, 0, 0, NULL);
+ printf("gluster_is_io_aligned len=%ld ret=%ld errno=%d\n", len, ret, errno);
return ret >= 0 || errno != EINVAL;
}
@@ -940,6 +941,9 @@ static void gluster_probe_alignment(BlockDriverState *bs, struct glfs_fd *fd,
error_setg(errp, "Could not find working O_DIRECT alignment");
error_append_hint(errp, "Try cache.direct=off\n");
}
+
+ printf("Probed aligment for %s request_alignment=%d\n",
+ bs->filename, bs->bl.request_alignment);
}
static void qemu_gluster_refresh_limits(BlockDriverState *bs, Error **errp)
Here is example run with volume with sector size of 512 bytes:
$ sudo mount -t glusterfs gluster1:/gv1 /tmp/gv1
$ dd if=/dev/zero bs=1M count=100 | tr "\0" "x" > /tmp/gv1/src.raw
$ truncate -s 100m /tmp/gv1/dst.raw
$ dd if=/dev/zero bs=1 count=1 of=/tmp/gv1/dst.raw conv=notrunc
$ ./qemu-img convert -n -f raw -O raw -t none -T none gluster://gluster1/gv1/src.raw gluster://gluster1/gv1/dst.raw
gluster_is_io_aligned len=1 ret=-1 errno=22
gluster_is_io_aligned len=512 ret=512 errno=0
Probed aligment for gluster://gluster1/gv1/src.raw request_alignment=512
gluster_is_io_aligned len=1 ret=-1 errno=22
gluster_is_io_aligned len=512 ret=512 errno=0
Probed aligment for gluster://gluster1/gv1/dst.raw request_alignment=512
And with volume with sector size of 4096 bytes:
$ sudo mount -t glusterfs gluster1:/gv0 /tmp/gv0
$ dd if=/dev/zero bs=1M count=100 | tr "\0" "x" > /tmp/gv0/src.raw
$ truncate -s 100m /tmp/gv0/dst.raw
$ dd if=/dev/zero bs=1 count=1 of=/tmp/gv0/dst.raw conv=notrunc
$ ./qemu-img convert -n -f raw -O raw -t none -T none gluster://gluster1/gv0/src.raw gluster://gluster1/gv0/dst.raw
gluster_is_io_aligned len=1 ret=-1 errno=22
gluster_is_io_aligned len=512 ret=-1 errno=22
gluster_is_io_aligned len=1024 ret=-1 errno=22
gluster_is_io_aligned len=2048 ret=-1 errno=22
gluster_is_io_aligned len=4096 ret=4096 errno=0
Probed aligment for gluster://gluster1/gv0/src.raw request_alignment=4096
gluster_is_io_aligned len=1 ret=-1 errno=22
gluster_is_io_aligned len=512 ret=-1 errno=22
gluster_is_io_aligned len=1024 ret=-1 errno=22
gluster_is_io_aligned len=2048 ret=-1 errno=22
gluster_is_io_aligned len=4096 ret=4096 errno=0
Probed aligment for gluster://gluster1/gv0/dst.raw request_alignment=4096