Re: [Virtio-fs] [PATCH] virtiofsd: make FUSE_REMOVEMAPPING support multiple entries

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peng Tao (tao.peng@linux.alibaba.com) wrote:
> The fuse wire protocol is changed so that we can unmap multiple
> mappings in a single call.
> 
> Signed-off-by: Peng Tao <tao.peng@linux.alibaba.com>

Hi,
  Thanks for the patch and apologies for not responding sooner

> ---
>  contrib/virtiofsd/fuse_kernel.h    |  9 +++++++--
>  contrib/virtiofsd/fuse_lowlevel.c  | 21 ++++++++++++++------
>  contrib/virtiofsd/fuse_lowlevel.h  |  5 +++--
>  contrib/virtiofsd/passthrough_ll.c | 31 ++++++++++++++++++++----------
>  4 files changed, 46 insertions(+), 20 deletions(-)
> 
> diff --git a/contrib/virtiofsd/fuse_kernel.h b/contrib/virtiofsd/fuse_kernel.h
> index ce46046a4f..093cacff02 100644
> --- a/contrib/virtiofsd/fuse_kernel.h
> +++ b/contrib/virtiofsd/fuse_kernel.h
> @@ -830,9 +830,14 @@ struct fuse_setupmapping_out {
>          uint64_t        len[FUSE_SETUPMAPPING_ENTRIES];
>  };
>  
> -struct fuse_removemapping_in {
> +struct fuse_removemapping_in_header {
>          /* An already open handle */
> -	uint64_t	fh;
> +        uint64_t        fh;
> +        /* number of fuse_removemapping_in follows */
> +        unsigned        num;

I think all fields in fuse structures are fixed length - e.g. uint32_t
or uint64_t.

> +};
> +
> +struct fuse_removemapping_in {
>          /* Offset into the dax to start the unmapping */
>          uint64_t        moffset;
>          /* Length of mapping required */

Miklos: Does this make sense for a fuse structure? It's that header
followed by 'num' of fuse_removemapping_in.

   
This is an interface change so we do have to coordinate with your kernel
change.

> diff --git a/contrib/virtiofsd/fuse_lowlevel.c b/contrib/virtiofsd/fuse_lowlevel.c
> index 111c6e1636..4619865c2c 100644
> --- a/contrib/virtiofsd/fuse_lowlevel.c
> +++ b/contrib/virtiofsd/fuse_lowlevel.c
> @@ -1907,21 +1907,30 @@ static void do_setupmapping(fuse_req_t req, fuse_ino_t nodeid,
>  static void do_removemapping(fuse_req_t req, fuse_ino_t nodeid,
>  			     struct fuse_mbuf_iter *iter)
>  {
> -	struct fuse_removemapping_in *arg;
> +	struct fuse_removemapping_in_header *header;
> +	struct fuse_removemapping_in *argp;
>          struct fuse_file_info fi;
>  
> -	arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
> -	if (!arg) {
> +	header = fuse_mbuf_iter_advance(iter, sizeof(*header));
> +	if (!header || header->num <= 0) {
> +		fprintf(stderr, "do_removemapping: invalid header %p\n", header);
> +		fuse_reply_err(req, EINVAL);
> +		return;
> +	}
> +
> +	argp = fuse_mbuf_iter_advance(iter, header->num * sizeof(*argp));
> +	if (!argp) {
> +		fprintf(stderr, "do_removemapping: invalid in, expected %d * %ld, has %ld - %ld\n",
> +				header->num, sizeof(*argp), iter->size, iter->pos);
>  		fuse_reply_err(req, EINVAL);
>  		return;
>  	}
>          memset(&fi, 0, sizeof(fi));
> -	fi.fh = arg->fh;
> +	fi.fh = header->fh;
>  
>  	if (req->se->op.removemapping)
> -		req->se->op.removemapping(req, req->se, nodeid, arg->moffset,
> -                                          arg->len, &fi);
> +		req->se->op.removemapping(req, req->se, nodeid, header->num, argp, &fi);
>  	else
>  		fuse_reply_err(req, ENOSYS);
>  }
> diff --git a/contrib/virtiofsd/fuse_lowlevel.h b/contrib/virtiofsd/fuse_lowlevel.h
> index 6a001c4605..b2b8747074 100644
> --- a/contrib/virtiofsd/fuse_lowlevel.h
> +++ b/contrib/virtiofsd/fuse_lowlevel.h
> @@ -23,6 +23,7 @@
>  #endif
>  
>  #include "fuse_common.h"
> +#include "fuse_kernel.h"
>  
>  #include <utime.h>
>  #include <fcntl.h>
> @@ -1200,8 +1201,8 @@ struct fuse_lowlevel_ops {
>           * TODO
>           */
>          void (*removemapping) (fuse_req_t req, struct fuse_session *se,
> -                               fuse_ino_t ino, uint64_t moffset,
> -                               uint64_t len, struct fuse_file_info *fi);
> +                               fuse_ino_t ino, unsigned num,
> +                               struct fuse_removemapping_in *args, struct fuse_file_info *fi);
>  };
>  
>  /**
> diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passthrough_ll.c
> index 1ddb68f1db..96d5468ead 100644
> --- a/contrib/virtiofsd/passthrough_ll.c
> +++ b/contrib/virtiofsd/passthrough_ll.c
> @@ -1925,20 +1925,31 @@ err:
>  }
>  
>  static void lo_removemapping(fuse_req_t req, struct fuse_session *se,
> -                             fuse_ino_t ino, uint64_t moffset,
> -                             uint64_t len, struct fuse_file_info *fi)
> +                             fuse_ino_t ino, unsigned num,
> +			     struct fuse_removemapping_in *argsp,
> +			     struct fuse_file_info *fi)
>  {
>          VhostUserFSSlaveMsg msg = { 0 };
>  	int ret = 0;
>  
> -	msg.len[0] = len;
> -	msg.c_offset[0] = moffset;
> -        if (fuse_virtio_unmap(se, &msg)) {
> -                fprintf(stderr,
> -                        "%s: unmap over virtio failed "
> -                        "(offset=0x%lx, len=0x%lx)\n", __func__, moffset, len);
> -                ret = EINVAL;
> -        }
> +	for (int i = 0; num > 0; i++, argsp++) {

Probably best to make 'i' unsigned as well.

Dave

> +		msg.len[i] = argsp->len;
> +		msg.c_offset[i] = argsp->moffset;
> +
> +		if (--num == 0 || i == VHOST_USER_FS_SLAVE_ENTRIES - 1) {
> +			if (fuse_virtio_unmap(se, &msg)) {
> +				fprintf(stderr,
> +					"%s: unmap over virtio failed "
> +					"(offset=0x%lx, len=0x%lx)\n", __func__, argsp->moffset, argsp->len);
> +				ret = EINVAL;
> +				break;
> +			}
> +			if (num > 0) {
> +				i = 0;
> +				memset(&msg, 0, sizeof(msg));
> +			}
> +		}
> +	}
>  
>  	fuse_reply_err(req, ret);
>  }
> -- 
> 2.17.1
> 
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--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK