Hi Markus,
On Fri, Feb 12, 2016 at 04:08:17PM +0100, Markus Pargmann wrote:
> For devices smaller than 4096 the current code results in a blockdevice
> size of 0.
>
> For devices with a different blocksize than 4096 the code potentially
> leads to more dropped blocks at the end of the file than necessary. For
> example a device with size 6144 would have only 4096 bytes available on
> client side even if the blocksize is set to 512.
>
> This patch tries to use the user-given blocksize if possible. Otherwise
> it falls back to using 4096.
>
> Signed-off-by: Markus Pargmann <[email protected]>
Applied, thanks.
> ---
> nbd-client.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/nbd-client.c b/nbd-client.c
> index 2c387f8c8c4c..40d6b7abac3c 100644
> --- a/nbd-client.c
> +++ b/nbd-client.c
> @@ -462,14 +462,25 @@ void setsizes(int nbd, u64 size64, int blocksize, u32
> flags) {
> if (size64>>12 > (uint64_t)~0UL)
> err("Device too large.\n");
> else {
> - if (ioctl(nbd, NBD_SET_BLKSIZE, 4096UL) < 0)
> + int tmp_blocksize = 4096;
> + if (size64 / (u64)blocksize <= (uint64_t)~0UL)
> + tmp_blocksize = blocksize;
> + if (ioctl(nbd, NBD_SET_BLKSIZE, tmp_blocksize) < 0) {
> + fprintf(stderr, "Failed to set blocksize %d\n",
> + tmp_blocksize);
> err("Ioctl/1.1a failed: %m\n");
> - size = (unsigned long)(size64>>12);
> + }
> + size = (unsigned long)(size64 / (u64)tmp_blocksize);
> if (ioctl(nbd, NBD_SET_SIZE_BLOCKS, size) < 0)
> err("Ioctl/1.1b failed: %m\n");
> - if (ioctl(nbd, NBD_SET_BLKSIZE, (unsigned long)blocksize) < 0)
> - err("Ioctl/1.1c failed: %m\n");
> - fprintf(stderr, "bs=%d, sz=%llu bytes\n", blocksize,
> 4096ULL*size);
> + if (tmp_blocksize != blocksize) {
> + if (ioctl(nbd, NBD_SET_BLKSIZE, (unsigned
> long)blocksize) < 0) {
> + fprintf(stderr, "Failed to set blocksize %d\n",
> + blocksize);
> + err("Ioctl/1.1c failed: %m\n");
> + }
> + }
> + fprintf(stderr, "bs=%d, sz=%llu bytes\n", blocksize,
> (u64)tmp_blocksize * size);
> }
>
> ioctl(nbd, NBD_CLEAR_SOCK);
> --
> 2.7.0.rc3
>
>
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