[src/trunk]: src/sys/kern physio can issue multiple concurrent I/O requests f...

[mlelstv <mlelstv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d09048e11dac
branches:  trunk
changeset: 449845:d09048e11dac
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Tue Mar 26 09:33:58 2019 +0000

description:
physio can issue multiple concurrent I/O requests for scatter/gather and
split requests, concurrent requests are limited to use multiple-of-DEV_BSIZE
offsets.

Restrict this to D_DISK devices.

For other devices fix uio accounting to allow arbitrary offsets again.

diffstat:

 sys/kern/kern_physio.c |  65 ++++++++++++++++++++++++++++++++++++++++----------
 1 files changed, 52 insertions(+), 13 deletions(-)

diffs (131 lines):

diff -r 9e399aa9523e -r d09048e11dac sys/kern/kern_physio.c
--- a/sys/kern/kern_physio.c    Tue Mar 26 09:22:17 2019 +0000
+++ b/sys/kern/kern_physio.c    Tue Mar 26 09:33:58 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_physio.c,v 1.93 2015/04/21 10:54:52 pooka Exp $   */
+/*     $NetBSD: kern_physio.c,v 1.94 2019/03/26 09:33:58 mlelstv Exp $ */
 
 /*-
  * Copyright (c) 1982, 1986, 1990, 1993
@@ -71,10 +71,11 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_physio.c,v 1.93 2015/04/21 10:54:52 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_physio.c,v 1.94 2019/03/26 09:33:58 mlelstv Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
+#include <sys/conf.h>
 #include <sys/buf.h>
 #include <sys/proc.h>
 #include <sys/once.h>
@@ -100,6 +101,7 @@
        int ps_error;
        int ps_failed;
        off_t ps_endoffset;
+       size_t ps_resid;
        buf_t *ps_orig_bp;
        kmutex_t ps_lock;
        kcondvar_t ps_cv;
@@ -152,6 +154,8 @@
                        ps->ps_error = bp->b_error;
                }
                ps->ps_failed++;
+
+               ps->ps_resid += todo - done;
        } else {
                KASSERT(bp->b_error == 0);
        }
@@ -220,6 +224,7 @@
        struct buf *bp = NULL;
        struct physio_stat *ps;
        int concurrency = physio_concurrency - 1;
+       int isdisk;
 
        error = RUN_ONCE(&physio_initialized, physio_init);
        if (__predict_false(error != 0)) {
@@ -237,9 +242,15 @@
        /* ps->ps_failed = 0; */
        ps->ps_orig_bp = obp;
        ps->ps_endoffset = -1;
+       ps->ps_resid = 0;
        mutex_init(&ps->ps_lock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&ps->ps_cv, "physio");
 
+       /* Allow concurrent I/O only for disks */
+       isdisk = cdev_type(dev) == D_DISK;
+       if (!isdisk)
+               concurrency = 0;
+
        /* Make sure we have a buffer, creating one if necessary. */
        if (obp != NULL) {
                mutex_enter(&bufcache_lock);
@@ -291,11 +302,30 @@
 
                        /* Set up the buffer for a maximum-sized transfer. */
                        bp->b_blkno = btodb(uio->uio_offset);
-                       if (dbtob(bp->b_blkno) != uio->uio_offset) {
-                               error = EINVAL;
-                               goto done;
+                       if (isdisk) {
+                               /*
+                                * For disks, check that offsets are at least block
+                                * aligned, the block addresses are used to track
+                                * errors of finished requests.
+                                */
+                               if (dbtob(bp->b_blkno) != uio->uio_offset) {
+                                       error = EINVAL;
+                                       goto done;
+                               }
+                               /*
+                                * Split request into MAXPHYS chunks
+                                */
+                               bp->b_bcount = MIN(MAXPHYS, iovp->iov_len);
+                       } else {
+                               /*
+                                * Verify that buffer can handle size
+                                */
+                               if (iovp->iov_len > MAXBSIZE) {
+                                       error = EINVAL;
+                                       goto done;
+                               }
+                               bp->b_bcount = iovp->iov_len;
                        }
-                       bp->b_bcount = MIN(MAXPHYS, iovp->iov_len);
                        bp->b_data = iovp->iov_base;
 
                        /*
@@ -364,16 +394,25 @@
        physio_wait(ps, 0);
        mutex_exit(&ps->ps_lock);
 
-       if (ps->ps_failed != 0) {
-               off_t delta;
+       KASSERT(ps->ps_failed || ps->ps_endoffset == -1);
+
+       /*
+        * Compute residual, for disks adjust for the
+        * lowest numbered block that returned an error.
+        */
+       if (isdisk) {
+               if (ps->ps_failed != 0) {
+                       off_t delta;
 
-               delta = uio->uio_offset - ps->ps_endoffset;
-               KASSERT(delta > 0);
-               uio->uio_resid += delta;
-               /* uio->uio_offset = ps->ps_endoffset; */
+                       delta = uio->uio_offset - ps->ps_endoffset;
+                       KASSERT(delta > 0);
+                       uio->uio_resid += delta;
+                       /* uio->uio_offset = ps->ps_endoffset; */
+               }
        } else {
-               KASSERT(ps->ps_endoffset == -1);
+               uio->uio_resid += ps->ps_resid;
        }
+
        if (bp != NULL && bp != obp) {
                putiobuf(bp);
        }