tentatively merged to cifs-2.6.git for-next pending more testing/review
On Tue, Feb 11, 2025 at 4:01 AM <nspmangalore@xxxxxxxxx> wrote:
>
> From: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
>
> The netfs library could break down a read request into
> multiple subrequests. When multichannel is used, there is
> potential to improve performance when each of these
> subrequests pick a different channel.
>
> Today we call cifs_pick_channel when the main read request
> is initialized in cifs_init_request. This change moves this to
> cifs_prepare_read, which is the right place to pick channel since
> it gets called for each subrequest.
>
> Interestingly cifs_prepare_write already does channel selection
> for individual subreq, but looks like it was missed for read.
> This is especially important when multichannel is used with
> increased rasize.
>
> In my test setup, with rasize set to 8MB, a sequential read
> of large file was taking 11.5s without this change. With the
> change, it completed in 9s. The difference is even more signigicant
> with bigger rasize.
>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Cc: David Howells <dhowells@xxxxxxxxxx>
> Signed-off-by: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
> ---
> fs/smb/client/cifsglob.h | 1 -
> fs/smb/client/file.c | 7 ++++---
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
> index a68434ad744a..243e4881528c 100644
> --- a/fs/smb/client/cifsglob.h
> +++ b/fs/smb/client/cifsglob.h
> @@ -1508,7 +1508,6 @@ struct cifs_io_parms {
> struct cifs_io_request {
> struct netfs_io_request rreq;
> struct cifsFileInfo *cfile;
> - struct TCP_Server_Info *server;
> pid_t pid;
> };
>
> diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
> index 79de2f2f9c41..8582cf61242c 100644
> --- a/fs/smb/client/file.c
> +++ b/fs/smb/client/file.c
> @@ -147,7 +147,7 @@ static int cifs_prepare_read(struct netfs_io_subrequest *subreq)
> struct netfs_io_request *rreq = subreq->rreq;
> struct cifs_io_subrequest *rdata = container_of(subreq, struct cifs_io_subrequest, subreq);
> struct cifs_io_request *req = container_of(subreq->rreq, struct cifs_io_request, rreq);
> - struct TCP_Server_Info *server = req->server;
> + struct TCP_Server_Info *server;
> struct cifs_sb_info *cifs_sb = CIFS_SB(rreq->inode->i_sb);
> size_t size;
> int rc = 0;
> @@ -156,6 +156,8 @@ static int cifs_prepare_read(struct netfs_io_subrequest *subreq)
> rdata->xid = get_xid();
> rdata->have_xid = true;
> }
> +
> + server = cifs_pick_channel(tlink_tcon(req->cfile->tlink)->ses);
> rdata->server = server;
>
> if (cifs_sb->ctx->rsize == 0)
> @@ -198,7 +200,7 @@ static void cifs_issue_read(struct netfs_io_subrequest *subreq)
> struct netfs_io_request *rreq = subreq->rreq;
> struct cifs_io_subrequest *rdata = container_of(subreq, struct cifs_io_subrequest, subreq);
> struct cifs_io_request *req = container_of(subreq->rreq, struct cifs_io_request, rreq);
> - struct TCP_Server_Info *server = req->server;
> + struct TCP_Server_Info *server = rdata->server;
> int rc = 0;
>
> cifs_dbg(FYI, "%s: op=%08x[%x] mapping=%p len=%zu/%zu\n",
> @@ -266,7 +268,6 @@ static int cifs_init_request(struct netfs_io_request *rreq, struct file *file)
> open_file = file->private_data;
> rreq->netfs_priv = file->private_data;
> req->cfile = cifsFileInfo_get(open_file);
> - req->server = cifs_pick_channel(tlink_tcon(req->cfile->tlink)->ses);
> if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
> req->pid = req->cfile->pid;
> } else if (rreq->origin != NETFS_WRITEBACK) {
> --
> 2.43.0
>
--
Thanks,
Steve
