Merge in the unified buffer cache code as found in NetBSD 2001/03/10. The

code is written mostly by Chuck Silvers <chuq@chuq.com>/<chs@netbsd.org>.

Tested for the past few weeks by many developers, should be in a pretty stable
state, but will require optimizations and additional cleanups.

1 files changed, 680 insertions, 3 deletions

diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c
index 8f426b3a3f5..61f6d0217e9 100644
--- a/sys/kern/vfs_default.c
+++ b/sys/kern/vfs_default.c
@@ -1,10 +1,9 @@
-/*       $OpenBSD: vfs_default.c,v 1.7 2001/06/25 03:28:03 csapuntz Exp $  */
-
+/*       $OpenBSD: vfs_default.c,v 1.8 2001/11/27 05:27:12 art Exp $  */
 
 /*
  *    Portions of this code are:
  *
- * Copyright (c) 1989, 1993
+ * Copyright (c) 1982, 1986, 1989, 1993
  *	The Regents of the University of California.  All rights reserved.
  * (c) UNIX System Laboratories, Inc.
  * All or some portions of this file are derived from material licensed
@@ -49,9 +48,11 @@
 #include <sys/vnode.h>
 #include <sys/namei.h>
 #include <sys/malloc.h>
+#include <sys/pool.h>
 #include <sys/event.h>
 #include <miscfs/specfs/specdev.h>
 
+#include <uvm/uvm.h>
 
 extern struct simplelock spechash_slock;
 
@@ -310,3 +311,679 @@ lease_check(void *v)
 {
 	return (0);
 }
+
+/*
+ * generic VM getpages routine.
+ * Return PG_BUSY pages for the given range,
+ * reading from backing store if necessary.
+ */
+
+int
+genfs_getpages(v)
+	void *v;
+{
+	struct vop_getpages_args /* {
+		struct vnode *a_vp;
+		voff_t a_offset;
+		vm_page_t *a_m;
+		int *a_count;
+		int a_centeridx;
+		vm_prot_t a_access_type;
+		int a_advice;
+		int a_flags;
+	} */ *ap = v;
+
+	off_t newsize, diskeof, memeof;
+	off_t offset, origoffset, startoffset, endoffset, raoffset;
+	daddr_t lbn, blkno;
+	int s, i, error, npages, orignpages, npgs, run, ridx, pidx, pcount;
+	int fs_bshift, fs_bsize, dev_bshift, dev_bsize;
+	int flags = ap->a_flags;
+	size_t bytes, iobytes, tailbytes, totalbytes, skipbytes;
+	vaddr_t kva;
+	struct buf *bp, *mbp;
+	struct vnode *vp = ap->a_vp;
+	struct uvm_object *uobj = &vp->v_uvm.u_obj;
+	struct vm_page *pgs[16];			/* XXXUBC 16 */
+	struct ucred *cred = curproc->p_ucred;		/* XXXUBC curproc */
+	boolean_t async = (flags & PGO_SYNCIO) == 0;
+	boolean_t write = (ap->a_access_type & VM_PROT_WRITE) != 0;
+	boolean_t sawhole = FALSE;
+	struct proc *p = curproc;
+	UVMHIST_FUNC("genfs_getpages"); UVMHIST_CALLED(ubchist);
+
+	UVMHIST_LOG(ubchist, "vp %p off 0x%x/%x count %d",
+		    vp, ap->a_offset >> 32, ap->a_offset, *ap->a_count);
+
+	/* XXXUBC temp limit */
+	if (*ap->a_count > 16) {
+		return EINVAL;
+	}
+
+	error = 0;
+	origoffset = ap->a_offset;
+	orignpages = *ap->a_count;
+	error = VOP_SIZE(vp, vp->v_uvm.u_size, &diskeof);
+	if (error) {
+		return error;
+	}
+	if (flags & PGO_PASTEOF) {
+		newsize = MAX(vp->v_uvm.u_size,
+			      origoffset + (orignpages << PAGE_SHIFT));
+		error = VOP_SIZE(vp, newsize, &memeof);
+		if (error) {
+			return error;
+		}
+	} else {
+		memeof = diskeof;
+	}
+	KASSERT(ap->a_centeridx >= 0 || ap->a_centeridx <= orignpages);
+	KASSERT((origoffset & (PAGE_SIZE - 1)) == 0 && origoffset >= 0);
+	KASSERT(orignpages > 0);
+
+	/*
+	 * Bounds-check the request.
+	 */
+
+	if (origoffset + (ap->a_centeridx << PAGE_SHIFT) >= memeof) {
+		if ((flags & PGO_LOCKED) == 0) {
+			simple_unlock(&uobj->vmobjlock);
+		}
+		UVMHIST_LOG(ubchist, "off 0x%x count %d goes past EOF 0x%x",
+			    origoffset, *ap->a_count, memeof,0);
+		return EINVAL;
+	}
+
+	/*
+	 * For PGO_LOCKED requests, just return whatever's in memory.
+	 */
+
+	if (flags & PGO_LOCKED) {
+		uvn_findpages(uobj, origoffset, ap->a_count, ap->a_m,
+			      UFP_NOWAIT|UFP_NOALLOC|UFP_NORDONLY);
+
+		return ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0;
+	}
+
+	/* vnode is VOP_LOCKed, uobj is locked */
+
+	if (write && (vp->v_bioflag & VBIOONSYNCLIST) == 0) {
+		vn_syncer_add_to_worklist(vp, syncdelay);
+	}
+
+	/*
+	 * find the requested pages and make some simple checks.
+	 * leave space in the page array for a whole block.
+	 */
+
+	fs_bshift = vp->v_mount->mnt_fs_bshift;
+	fs_bsize = 1 << fs_bshift;
+	dev_bshift = vp->v_mount->mnt_dev_bshift;
+	dev_bsize = 1 << dev_bshift;
+	KASSERT((diskeof & (dev_bsize - 1)) == 0);
+	KASSERT((memeof & (dev_bsize - 1)) == 0);
+
+	orignpages = MIN(orignpages,
+	    round_page(memeof - origoffset) >> PAGE_SHIFT);
+	npages = orignpages;
+	startoffset = origoffset & ~(fs_bsize - 1);
+	endoffset = round_page((origoffset + (npages << PAGE_SHIFT)
+				+ fs_bsize - 1) & ~(fs_bsize - 1));
+	endoffset = MIN(endoffset, round_page(memeof));
+	ridx = (origoffset - startoffset) >> PAGE_SHIFT;
+
+	memset(pgs, 0, sizeof(pgs));
+	uvn_findpages(uobj, origoffset, &npages, &pgs[ridx], UFP_ALL);
+
+	/*
+	 * if PGO_OVERWRITE is set, don't bother reading the pages.
+	 * PGO_OVERWRITE also means that the caller guarantees
+	 * that the pages already have backing store allocated.
+	 */
+
+	if (flags & PGO_OVERWRITE) {
+		UVMHIST_LOG(ubchist, "PGO_OVERWRITE",0,0,0,0);
+
+		for (i = 0; i < npages; i++) {
+			struct vm_page *pg = pgs[ridx + i];
+
+			if (pg->flags & PG_FAKE) {
+				uvm_pagezero(pg);
+				pg->flags &= ~(PG_FAKE);
+			}
+			pg->flags &= ~(PG_RDONLY);
+		}
+		npages += ridx;
+		goto out;
+	}
+
+	/*
+	 * if the pages are already resident, just return them.
+	 */
+
+	for (i = 0; i < npages; i++) {
+		struct vm_page *pg = pgs[ridx + i];
+
+		if ((pg->flags & PG_FAKE) ||
+		    (write && (pg->flags & PG_RDONLY))) {
+			break;
+		}
+	}
+	if (i == npages) {
+		UVMHIST_LOG(ubchist, "returning cached pages", 0,0,0,0);
+		raoffset = origoffset + (orignpages << PAGE_SHIFT);
+		npages += ridx;
+		goto raout;
+	}
+
+	/*
+	 * the page wasn't resident and we're not overwriting,
+	 * so we're going to have to do some i/o.
+	 * find any additional pages needed to cover the expanded range.
+	 */
+
+	if (startoffset != origoffset) {
+
+		/*
+		 * XXXUBC we need to avoid deadlocks caused by locking
+		 * additional pages at lower offsets than pages we
+		 * already have locked.  for now, unlock them all and
+		 * start over.
+		 */
+
+		for (i = 0; i < npages; i++) {
+			struct vm_page *pg = pgs[ridx + i];
+
+			if (pg->flags & PG_FAKE) {
+				pg->flags |= PG_RELEASED;
+			}
+		}
+		uvm_page_unbusy(&pgs[ridx], npages);
+		memset(pgs, 0, sizeof(pgs));
+
+		UVMHIST_LOG(ubchist, "reset npages start 0x%x end 0x%x",
+			    startoffset, endoffset, 0,0);
+		npages = (endoffset - startoffset) >> PAGE_SHIFT;
+		npgs = npages;
+		uvn_findpages(uobj, startoffset, &npgs, pgs, UFP_ALL);
+	}
+	simple_unlock(&uobj->vmobjlock);
+
+	/*
+	 * read the desired page(s).
+	 */
+
+	totalbytes = npages << PAGE_SHIFT;
+	bytes = MIN(totalbytes, MAX(diskeof - startoffset, 0));
+	tailbytes = totalbytes - bytes;
+	skipbytes = 0;
+
+	kva = uvm_pagermapin(pgs, npages, UVMPAGER_MAPIN_WAITOK |
+			     UVMPAGER_MAPIN_READ);
+
+	s = splbio();
+	mbp = pool_get(&bufpool, PR_WAITOK);
+	splx(s);
+	mbp->b_bufsize = totalbytes;
+	mbp->b_data = (void *)kva;
+	mbp->b_resid = mbp->b_bcount = bytes;
+	mbp->b_flags = B_BUSY|B_READ| (async ? B_CALL : 0);
+	mbp->b_iodone = uvm_aio_biodone;
+	mbp->b_vp = vp;
+	LIST_INIT(&mbp->b_dep);
+
+	/*
+	 * if EOF is in the middle of the range, zero the part past EOF.
+	 */
+
+	if (tailbytes > 0) {
+		memset((void *)(kva + bytes), 0, tailbytes);
+	}
+
+	/*
+	 * now loop over the pages, reading as needed.
+	 */
+
+	if (write) {
+		lockmgr(&vp->v_glock, LK_EXCLUSIVE, NULL, p);
+	} else {
+		lockmgr(&vp->v_glock, LK_SHARED, NULL, p);
+	}
+
+	bp = NULL;
+	for (offset = startoffset;
+	     bytes > 0;
+	     offset += iobytes, bytes -= iobytes) {
+
+		/*
+		 * skip pages which don't need to be read.
+		 */
+
+		pidx = (offset - startoffset) >> PAGE_SHIFT;
+		while ((pgs[pidx]->flags & PG_FAKE) == 0) {
+			size_t b;
+
+			KASSERT((offset & (PAGE_SIZE - 1)) == 0);
+			b = MIN(PAGE_SIZE, bytes);
+			offset += b;
+			bytes -= b;
+			skipbytes += b;
+			pidx++;
+			UVMHIST_LOG(ubchist, "skipping, new offset 0x%x",
+				    offset, 0,0,0);
+			if (bytes == 0) {
+				goto loopdone;
+			}
+		}
+
+		/*
+		 * bmap the file to find out the blkno to read from and
+		 * how much we can read in one i/o.  if bmap returns an error,
+		 * skip the rest of the top-level i/o.
+		 */
+
+		lbn = offset >> fs_bshift;
+		error = VOP_BMAP(vp, lbn, NULL, &blkno, &run);
+		if (error) {
+			UVMHIST_LOG(ubchist, "VOP_BMAP lbn 0x%x -> %d\n",
+				    lbn, error,0,0);
+			skipbytes += bytes;
+			goto loopdone;
+		}
+
+		/*
+		 * see how many pages can be read with this i/o.
+		 * reduce the i/o size if necessary to avoid
+		 * overwriting pages with valid data.
+		 */
+
+		iobytes = MIN((((off_t)lbn + 1 + run) << fs_bshift) - offset,
+		    bytes);
+		if (offset + iobytes > round_page(offset)) {
+			pcount = 1;
+			while (pidx + pcount < npages &&
+			       pgs[pidx + pcount]->flags & PG_FAKE) {
+				pcount++;
+			}
+			iobytes = MIN(iobytes, (pcount << PAGE_SHIFT) -
+				      (offset - trunc_page(offset)));
+		}
+
+		/*
+		 * if this block isn't allocated, zero it instead of reading it.
+		 * if this is a read access, mark the pages we zeroed PG_RDONLY.
+		 */
+
+		if (blkno < 0) {
+			UVMHIST_LOG(ubchist, "lbn 0x%x -> HOLE", lbn,0,0,0);
+
+			sawhole = TRUE;
+			memset((char *)kva + (offset - startoffset), 0,
+			       iobytes);
+			skipbytes += iobytes;
+
+			if (!write) {
+				int holepages =
+					(round_page(offset + iobytes) - 
+					 trunc_page(offset)) >> PAGE_SHIFT;
+				for (i = 0; i < holepages; i++) {
+					pgs[pidx + i]->flags |= PG_RDONLY;
+				}
+			}
+			continue;
+		}
+
+		/*
+		 * allocate a sub-buf for this piece of the i/o
+		 * (or just use mbp if there's only 1 piece),
+		 * and start it going.
+		 */
+
+		if (offset == startoffset && iobytes == bytes) {
+			bp = mbp;
+		} else {
+			s = splbio();
+			bp = pool_get(&bufpool, PR_WAITOK);
+			splx(s);
+			bp->b_data = (char *)kva + offset - startoffset;
+			bp->b_resid = bp->b_bcount = iobytes;
+			bp->b_flags = B_BUSY|B_READ|B_CALL;
+			bp->b_iodone = uvm_aio_biodone1;
+			bp->b_vp = vp;
+			LIST_INIT(&bp->b_dep);
+		}
+		bp->b_lblkno = 0;
+		bp->b_private = mbp;
+
+		/* adjust physical blkno for partial blocks */
+		bp->b_blkno = blkno + ((offset - ((off_t)lbn << fs_bshift)) >>
+				       dev_bshift);
+
+		UVMHIST_LOG(ubchist, "bp %p offset 0x%x bcount 0x%x blkno 0x%x",
+			    bp, offset, iobytes, bp->b_blkno);
+
+		VOP_STRATEGY(bp);
+	}
+
+loopdone:
+	if (skipbytes) {
+		s = splbio();
+		if (error) {
+			mbp->b_flags |= B_ERROR;
+			mbp->b_error = error;
+		}
+		mbp->b_resid -= skipbytes;
+		if (mbp->b_resid == 0) {
+			biodone(mbp);
+		}
+		splx(s);
+	}
+
+	if (async) {
+		UVMHIST_LOG(ubchist, "returning PEND",0,0,0,0);
+		lockmgr(&vp->v_glock, LK_RELEASE, NULL, p);
+		return EINPROGRESS;
+	}
+	if (bp != NULL) {
+		error = biowait(mbp);
+	}
+	s = splbio();
+	pool_put(&bufpool, mbp);
+	splx(s);
+	uvm_pagermapout(kva, npages);
+	raoffset = startoffset + totalbytes;
+
+	/*
+	 * if this we encountered a hole then we have to do a little more work.
+	 * for read faults, we marked the page PG_RDONLY so that future
+	 * write accesses to the page will fault again.
+	 * for write faults, we must make sure that the backing store for
+	 * the page is completely allocated while the pages are locked.
+	 */
+
+	if (error == 0 && sawhole && write) {
+		error = VOP_BALLOCN(vp, startoffset, npages << PAGE_SHIFT,
+				   cred, 0);
+		if (error) {
+			UVMHIST_LOG(ubchist, "balloc lbn 0x%x -> %d",
+				    lbn, error,0,0);
+			lockmgr(&vp->v_glock, LK_RELEASE, NULL, p);
+			simple_lock(&uobj->vmobjlock);
+			goto out;
+		}
+	}
+	lockmgr(&vp->v_glock, LK_RELEASE, NULL, p);
+	simple_lock(&uobj->vmobjlock);
+
+	/*
+	 * see if we want to start any readahead.
+	 * XXXUBC for now, just read the next 128k on 64k boundaries.
+	 * this is pretty nonsensical, but it is 50% faster than reading
+	 * just the next 64k.
+	 */
+
+raout:
+	if (!error && !async && !write && ((int)raoffset & 0xffff) == 0 &&
+	    PAGE_SHIFT <= 16) {
+		int racount;
+
+		racount = 1 << (16 - PAGE_SHIFT);
+		(void) VOP_GETPAGES(vp, raoffset, NULL, &racount, 0,
+				    VM_PROT_READ, 0, 0);
+		simple_lock(&uobj->vmobjlock);
+
+		racount = 1 << (16 - PAGE_SHIFT);
+		(void) VOP_GETPAGES(vp, raoffset + 0x10000, NULL, &racount, 0,
+				    VM_PROT_READ, 0, 0);
+		simple_lock(&uobj->vmobjlock);
+	}
+
+	/*
+	 * we're almost done!  release the pages...
+	 * for errors, we free the pages.
+	 * otherwise we activate them and mark them as valid and clean.
+	 * also, unbusy pages that were not actually requested.
+	 */
+
+out:
+	if (error) {
+		uvm_lock_pageq();
+		for (i = 0; i < npages; i++) {
+			if (pgs[i] == NULL) {
+				continue;
+			}
+			UVMHIST_LOG(ubchist, "examining pg %p flags 0x%x",
+				    pgs[i], pgs[i]->flags, 0,0);
+			if (pgs[i]->flags & PG_WANTED) {
+				wakeup(pgs[i]);
+			}
+			if (pgs[i]->flags & PG_RELEASED) {
+				uvm_unlock_pageq();
+				(uobj->pgops->pgo_releasepg)(pgs[i], NULL);
+				uvm_lock_pageq();
+				continue;
+			}
+			if (pgs[i]->flags & PG_FAKE) {
+				uvm_pagefree(pgs[i]);
+				continue;
+			}
+			uvm_pageactivate(pgs[i]);
+			pgs[i]->flags &= ~(PG_WANTED|PG_BUSY);
+			UVM_PAGE_OWN(pgs[i], NULL);
+		}
+		uvm_unlock_pageq();
+		simple_unlock(&uobj->vmobjlock);
+		UVMHIST_LOG(ubchist, "returning error %d", error,0,0,0);
+		return error;
+	}
+
+	UVMHIST_LOG(ubchist, "succeeding, npages %d", npages,0,0,0);
+	uvm_lock_pageq();
+	for (i = 0; i < npages; i++) {
+		if (pgs[i] == NULL) {
+			continue;
+		}
+		UVMHIST_LOG(ubchist, "examining pg %p flags 0x%x",
+			    pgs[i], pgs[i]->flags, 0,0);
+		if (pgs[i]->flags & PG_FAKE) {
+			UVMHIST_LOG(ubchist, "unfaking pg %p offset 0x%x",
+				    pgs[i], pgs[i]->offset,0,0);
+			pgs[i]->flags &= ~(PG_FAKE);
+			pmap_clear_modify(pgs[i]);
+			pmap_clear_reference(pgs[i]);
+		}
+		if (write) {
+			pgs[i]->flags &= ~(PG_RDONLY);
+		}
+		if (i < ridx || i >= ridx + orignpages || async) {
+			UVMHIST_LOG(ubchist, "unbusy pg %p offset 0x%x",
+				    pgs[i], pgs[i]->offset,0,0);
+			if (pgs[i]->flags & PG_WANTED) {
+				wakeup(pgs[i]);
+			}
+			if (pgs[i]->flags & PG_RELEASED) {
+				uvm_unlock_pageq();
+				(uobj->pgops->pgo_releasepg)(pgs[i], NULL);
+				uvm_lock_pageq();
+				continue;
+			}
+			uvm_pageactivate(pgs[i]);
+			pgs[i]->flags &= ~(PG_WANTED|PG_BUSY);
+			UVM_PAGE_OWN(pgs[i], NULL);
+		}
+	}
+	uvm_unlock_pageq();
+	simple_unlock(&uobj->vmobjlock);
+	if (ap->a_m != NULL) {
+		memcpy(ap->a_m, &pgs[ridx],
+		       orignpages * sizeof(struct vm_page *));
+	}
+	return 0;
+}
+
+/*
+ * generic VM putpages routine.
+ * Write the given range of pages to backing store.
+ */
+
+int
+genfs_putpages(v)
+	void *v;
+{
+	struct vop_putpages_args /* {
+		struct vnode *a_vp;
+		struct vm_page **a_m;
+		int a_count;
+		int a_flags;
+		int *a_rtvals;
+	} */ *ap = v;
+
+	int s, error, npages, run;
+	int fs_bshift, dev_bshift, dev_bsize;
+	vaddr_t kva;
+	off_t eof, offset, startoffset;
+	size_t bytes, iobytes, skipbytes;
+	daddr_t lbn, blkno;
+	struct vm_page *pg;
+	struct buf *mbp, *bp;
+	struct vnode *vp = ap->a_vp;
+	boolean_t async = (ap->a_flags & PGO_SYNCIO) == 0;
+	UVMHIST_FUNC("genfs_putpages"); UVMHIST_CALLED(ubchist);
+	UVMHIST_LOG(ubchist, "vp %p offset 0x%x count %d",
+		    vp, ap->a_m[0]->offset, ap->a_count, 0);
+
+	simple_unlock(&vp->v_uvm.u_obj.vmobjlock);
+
+	error = VOP_SIZE(vp, vp->v_uvm.u_size, &eof);
+	if (error) {
+		return error;
+	}
+
+	error = 0;
+	npages = ap->a_count;
+	fs_bshift = vp->v_mount->mnt_fs_bshift;
+	dev_bshift = vp->v_mount->mnt_dev_bshift;
+	dev_bsize = 1 << dev_bshift;
+	KASSERT((eof & (dev_bsize - 1)) == 0);
+
+	pg = ap->a_m[0];
+	startoffset = pg->offset;
+	bytes = MIN(npages << PAGE_SHIFT, eof - startoffset);
+	skipbytes = 0;
+	KASSERT(bytes != 0);
+
+	kva = uvm_pagermapin(ap->a_m, npages, UVMPAGER_MAPIN_WAITOK);
+
+	s = splbio();
+	vp->v_numoutput += 2;
+	mbp = pool_get(&bufpool, PR_WAITOK);
+	UVMHIST_LOG(ubchist, "vp %p mbp %p num now %d bytes 0x%x",
+		    vp, mbp, vp->v_numoutput, bytes);
+	splx(s);
+	mbp->b_bufsize = npages << PAGE_SHIFT;
+	mbp->b_data = (void *)kva;
+	mbp->b_resid = mbp->b_bcount = bytes;
+	mbp->b_flags = B_BUSY|B_WRITE|B_AGE |
+		(async ? B_CALL : 0) |
+		(curproc == uvm.pagedaemon_proc ? B_PDAEMON : 0);
+	mbp->b_iodone = uvm_aio_biodone;
+	mbp->b_vp = vp;
+	LIST_INIT(&mbp->b_dep);
+
+	bp = NULL;
+	for (offset = startoffset;
+	     bytes > 0;
+	     offset += iobytes, bytes -= iobytes) {
+		lbn = offset >> fs_bshift;
+		error = VOP_BMAP(vp, lbn, NULL, &blkno, &run);
+		if (error) {
+			UVMHIST_LOG(ubchist, "VOP_BMAP() -> %d", error,0,0,0);
+			skipbytes += bytes;
+			bytes = 0;
+			break;
+		}
+
+		iobytes = MIN((((off_t)lbn + 1 + run) << fs_bshift) - offset,
+		    bytes);
+		if (blkno == (daddr_t)-1) {
+			skipbytes += iobytes;
+			continue;
+		}
+
+		/* if it's really one i/o, don't make a second buf */
+		if (offset == startoffset && iobytes == bytes) {
+			bp = mbp;
+		} else {
+			s = splbio();
+			vp->v_numoutput++;
+			bp = pool_get(&bufpool, PR_WAITOK);
+			UVMHIST_LOG(ubchist, "vp %p bp %p num now %d",
+				    vp, bp, vp->v_numoutput, 0);
+			splx(s);
+			bp->b_data = (char *)kva +
+				(vaddr_t)(offset - pg->offset);
+			bp->b_resid = bp->b_bcount = iobytes;
+			bp->b_flags = B_BUSY|B_WRITE|B_CALL|B_ASYNC;
+			bp->b_iodone = uvm_aio_biodone1;
+			bp->b_vp = vp;
+			LIST_INIT(&bp->b_dep);
+		}
+		bp->b_lblkno = 0;
+		bp->b_private = mbp;
+
+		/* adjust physical blkno for partial blocks */
+		bp->b_blkno = blkno + ((offset - ((off_t)lbn << fs_bshift)) >>
+				       dev_bshift);
+		UVMHIST_LOG(ubchist, "vp %p offset 0x%x bcount 0x%x blkno 0x%x",
+			    vp, offset, bp->b_bcount, bp->b_blkno);
+		VOP_STRATEGY(bp);
+	}
+	if (skipbytes) {
+		UVMHIST_LOG(ubchist, "skipbytes %d", skipbytes, 0,0,0);
+		s = splbio();
+		mbp->b_resid -= skipbytes;
+		if (error) {
+			mbp->b_flags |= B_ERROR;
+			mbp->b_error = error;
+		}
+		if (mbp->b_resid == 0) {
+			biodone(mbp);
+		}
+		splx(s);
+	}
+	if (async) {
+		UVMHIST_LOG(ubchist, "returning PEND", 0,0,0,0);
+		return EINPROGRESS;
+	}
+	if (bp != NULL) {
+		UVMHIST_LOG(ubchist, "waiting for mbp %p", mbp,0,0,0);
+		error = biowait(mbp);
+	}
+	if (bioops.io_pageiodone) {
+		(*bioops.io_pageiodone)(mbp);
+	}
+	s = splbio();
+	if (mbp->b_vp)
+		vwakeup(mbp->b_vp);
+	pool_put(&bufpool, mbp);
+	splx(s);
+	uvm_pagermapout(kva, npages);
+	UVMHIST_LOG(ubchist, "returning, error %d", error,0,0,0);
+	return error;
+}
+
+int
+genfs_size(v)
+	void *v;
+{
+	struct vop_size_args /* {
+		struct vnode *a_vp;
+		off_t a_size;
+		off_t *a_eobp;
+	} */ *ap = v;
+	int bsize;
+
+	bsize = 1 << ap->a_vp->v_mount->mnt_fs_bshift;
+	*ap->a_eobp = (ap->a_size + bsize - 1) & ~(bsize - 1);
+	return 0;
+}