[src/netbsd-3]: src/sys/ufs/ffs Pull up following revision(s) (requested by y...

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

details:   https://anonhg.NetBSD.org/src/rev/8cd5ade6997d
branches:  netbsd-3
changeset: 577381:8cd5ade6997d
user:      tron <tron%NetBSD.org@localhost>
date:      Fri Oct 21 11:27:00 2005 +0000

description:
Pull up following revision(s) (requested by yamt in ticket #845):
        sys/ufs/ffs/ffs_softdep.c: revision 1.70 via patch
- for pagecache dependency, track which page in the block
  has been written or not individually by (ab)using b_resid
  in pcbp as a bitmap.
- add a comment to explain why it's needed.
PR/15364.  reviewed by Chuck Silvers.

diffstat:

 sys/ufs/ffs/ffs_softdep.c |  44 +++++++++++++++++++++++++++++---------------
 1 files changed, 29 insertions(+), 15 deletions(-)

diffs (111 lines):

diff -r 5c4f8ac78128 -r 8cd5ade6997d sys/ufs/ffs/ffs_softdep.c
--- a/sys/ufs/ffs/ffs_softdep.c Fri Oct 21 11:25:56 2005 +0000
+++ b/sys/ufs/ffs/ffs_softdep.c Fri Oct 21 11:27:00 2005 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ffs_softdep.c,v 1.63.2.1 2005/05/07 15:04:48 tron Exp $        */
+/*     $NetBSD: ffs_softdep.c,v 1.63.2.2 2005/10/21 11:27:00 tron Exp $        */
 
 /*
  * Copyright 1998 Marshall Kirk McKusick. All Rights Reserved.
@@ -33,7 +33,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ffs_softdep.c,v 1.63.2.1 2005/05/07 15:04:48 tron Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ffs_softdep.c,v 1.63.2.2 2005/10/21 11:27:00 tron Exp $");
 
 #include <sys/param.h>
 #include <sys/buf.h>
@@ -197,6 +197,9 @@
 void softdep_flush_vnode __P((struct vnode *, daddr_t));
 static void softdep_trackbufs(struct inode *, int, boolean_t);
 
+#define        PCBP_BITMAP(off, size) \
+       (((1 << howmany((size), PAGE_SIZE)) - 1) << ((off) >> PAGE_SHIFT))
+
 /*
  * Exported softdep operations.
  */
@@ -5792,6 +5795,11 @@
         * Enter pagecache dependency buf in hash.
         * Always reset b_resid to be the full amount of data in the block
         * since the caller has the corresponding pages locked and dirty.
+        *
+        * Note that we are using b_resid as a bitmap, so that
+        * we can track which pages are written.  As pages can be re-dirtied
+        * and re-written in the mean time, byte-count is not suffice for
+        * our purpose.
         */
 
        bp = softdep_lookup_pcbp(vp, lbn);
@@ -5803,9 +5811,13 @@
                LIST_INSERT_HEAD(&pcbphashhead[PCBPHASH(vp, lbn)], bp, b_hash);
                LIST_INSERT_HEAD(&ip->i_pcbufhd, bp, b_vnbufs);
        }
-       bp->b_bcount = bp->b_resid = size;
-       UVMHIST_LOG(ubchist, "vp = %p, lbn = %" PRId64
-           ", bp = %p, bcount = resid = %ld", vp, lbn, bp, size);
+       bp->b_bcount = size;
+       KASSERT(size <= PAGE_SIZE * sizeof(bp->b_resid) * CHAR_BIT);
+       bp->b_resid = PCBP_BITMAP(0, size);
+       UVMHIST_LOG(ubchist, "vp = %p, lbn = %ld, "
+           "bp = %p, bcount = %ld", vp, lbn, bp, size);
+       UVMHIST_LOG(ubchist, "b_resid = %ld",
+           bp->b_resid, 0, 0, 0);
        return bp;
 }
 
@@ -5932,7 +5944,7 @@
        struct worklist *wk;
        daddr_t lbn;
        voff_t off;
-       long iosize = bp->b_bcount;
+       int iosize = bp->b_bcount;
        int size, asize, bshift, bsize;
        int i;
        UVMHIST_FUNC("softdep_pageiodone"); UVMHIST_CALLED(ubchist);
@@ -5945,12 +5957,14 @@
        for (i = 0; i < npages; i++) {
                pg = uvm_pageratop((vaddr_t)bp->b_data + (i << PAGE_SHIFT));
                if (pg == NULL) {
-                       continue;
+                       panic("%s: no page", __func__);
                }
 
                for (off = pg->offset;
                     off < pg->offset + PAGE_SIZE;
                     off += bsize) {
+                       int pgmask;
+
                        size = MIN(asize, iosize);
                        iosize -= size;
                        lbn = off >> bshift;
@@ -5961,20 +5975,20 @@
                                continue;
                        }
                        UVMHIST_LOG(ubchist,
-                           "bcount %ld resid %ld vp %p lbn %" PRId64,
+                           "bcount %ld resid %ld vp %p lbn %ld",
                            pcbp ? pcbp->b_bcount : -1,
                            pcbp ? pcbp->b_resid : -1, vp, lbn);
                        UVMHIST_LOG(ubchist,
                            "pcbp %p iosize %ld, size %d, asize %d",
                            pcbp, iosize, size, asize);
-                       pcbp->b_resid -= size;
-                       if (pcbp->b_resid < 0) {
-                               panic("softdep_pageiodone: "
-                                   "resid < 0, vp %p lbn 0x%" PRIx64 " pcbp %p"
-                                   " iosize %ld, size %d, asize %d, bsize %d",
-                                   vp, lbn, pcbp, iosize, size, asize, bsize);
+                       pgmask = PCBP_BITMAP(off & (bsize - 1), size);
+                       if ((~pcbp->b_resid & pgmask) != 0) {
+                               UVMHIST_LOG(ubchist,
+                                   "multiple write resid %lx, pgmask %lx",
+                                   pcbp->b_resid, pgmask, 0, 0);
                        }
-                       if (pcbp->b_resid > 0) {
+                       pcbp->b_resid &= ~pgmask;
+                       if (pcbp->b_resid != 0) {
                                continue;
                        }