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use the new flags PG_RDONLY and UFP_NORDONLY to ensure that
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any page which becomes dirty will have backing store allocated.
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chs committed Jun 2, 1999
1 parent 7c5f902 commit 7f88834
Showing 1 changed file with 66 additions and 56 deletions.
122 changes: 66 additions & 56 deletions sys/ufs/ffs/ffs_vnops.c
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@@ -1,4 +1,4 @@
/* $NetBSD: ffs_vnops.c,v 1.16.2.5 1999/05/30 15:16:01 chs Exp $ */ /* $NetBSD: ffs_vnops.c,v 1.16.2.6 1999/06/02 05:05:24 chs Exp $ */


/* /*
* Copyright (c) 1982, 1986, 1989, 1993 * Copyright (c) 1982, 1986, 1989, 1993
Expand Down Expand Up @@ -282,13 +282,14 @@ ffs_getpages(v)
int a_flags; int a_flags;
} */ *ap = v; } */ *ap = v;


int error, npages; int error, npages, cidx, i;
struct buf tmpbuf, *bp; struct buf tmpbuf, *bp;
struct vnode *vp = ap->a_vp; struct vnode *vp = ap->a_vp;
struct uvm_object *uobj = &vp->v_uvm.u_obj; struct uvm_object *uobj = &vp->v_uvm.u_obj;
struct inode *ip = VTOI(vp); struct inode *ip = VTOI(vp);
struct fs *fs = ip->i_fs; struct fs *fs = ip->i_fs;
struct vm_page *pg; struct vm_page *pg, *pgs[16]; /* XXX 16 */
struct ucred *cred = curproc->p_ucred;
off_t offset; off_t offset;
UVMHIST_FUNC("ffs_getpages"); UVMHIST_CALLED(ubchist); UVMHIST_FUNC("ffs_getpages"); UVMHIST_CALLED(ubchist);


Expand All @@ -301,7 +302,7 @@ ffs_getpages(v)


if (ap->a_flags & PGO_LOCKED) { if (ap->a_flags & PGO_LOCKED) {
uvn_findpages(uobj, ap->a_offset, ap->a_count, ap->a_m, uvn_findpages(uobj, ap->a_offset, ap->a_count, ap->a_m,
UFP_NOWAIT|UFP_NOALLOC); UFP_NOWAIT|UFP_NOALLOC|UFP_NORDONLY);


/* XXX PGO_ALLPAGES? */ /* XXX PGO_ALLPAGES? */
return ap->a_m[ap->a_centeridx] == NULL ? return ap->a_m[ap->a_centeridx] == NULL ?
Expand Down Expand Up @@ -346,18 +347,21 @@ ffs_getpages(v)
* if the page is already resident, just return it. * if the page is already resident, just return it.
*/ */


if (pg && (pg->flags & PG_FAKE) == 0) { if ((pg->flags & PG_FAKE) == 0 &&
!((ap->a_access_type & VM_PROT_WRITE) && (pg->flags & PG_RDONLY))) {
ap->a_m[ap->a_centeridx] = pg; ap->a_m[ap->a_centeridx] = pg;
return VM_PAGER_OK; return VM_PAGER_OK;
} }


UVMHIST_LOG(ubchist, "pg %p flags 0x%x access_type 0x%x",
pg, (int)pg->flags, (int)ap->a_access_type, 0);

/* /*
* ok, really read the desired page. * ok, really read the desired page.
*/ */


bp = &tmpbuf; bp = &tmpbuf;
bzero(bp, sizeof *bp); bzero(bp, sizeof *bp);

bp->b_lblkno = lblkno(fs, offset); bp->b_lblkno = lblkno(fs, offset);
error = VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL); error = VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL);
if (error) { if (error) {
Expand All @@ -366,48 +370,77 @@ ffs_getpages(v)
goto out; goto out;
} }
if (bp->b_blkno == (daddr_t)-1) { if (bp->b_blkno == (daddr_t)-1) {
UVMHIST_LOG(ubchist, "lbn 0x%x -> HOLE", bp->b_lblkno,0,0,0);

/*
* for read faults, we can skip the block allocation
* by marking the page PG_RDONLY and PG_CLEAN.
*/

if ((ap->a_access_type & VM_PROT_WRITE) == 0) {
uvm_pagezero(pg);
pg->flags |= PG_CLEAN|PG_RDONLY;
UVMHIST_LOG(ubchist, "setting PG_RDONLY", 0,0,0,0);
goto out;
}


/* /*
* XXX pre-allocate blocks here someday? * for write faults, we must now allocate the backing store
* ... only for write accesses. * and make sure the block is zeroed.
* for read accesses we can skip the block allocation
* if we can arrange to be called again
* when a subsequent write access occurs.
* needs support in uvm_fault().
*/ */


uvm_pagezero(pg); error = ffs_balloc(ip, bp->b_lblkno,
UVMHIST_LOG(ubchist, "VOP_BMAP lbn 0x%x -> blkno 0x%x\n", blksize(fs, ip, bp->b_lblkno),
bp->b_lblkno, bp->b_blkno,0,0); cred, NULL, &bp->b_blkno, 0);
if (error) {
UVMHIST_LOG(ubchist, "ffs_balloc lbn 0x%x -> %d",
bp->b_lblkno, error,0,0);
goto out;
}

simple_lock(&uobj->vmobjlock);
uvm_pager_dropcluster(uobj, NULL, &pg, &npages, 0, 0);
npages = fs->fs_bsize >> PAGE_SHIFT;
uvn_findpages(uobj, offset & ~((off_t)fs->fs_bsize - 1),
&npages, pgs, 0);
for (i = 0; i < npages; i++) {
uvm_pagezero(pgs[i]);
uvm_pageactivate(pgs[i]);

/*
* don't bother clearing mod/ref, the block is
* being modified anyways.
*/

pgs[i]->flags &= ~(PG_FAKE|PG_RDONLY);
}
cidx = (offset >> PAGE_SHIFT) - (pgs[0]->offset >> PAGE_SHIFT);
pg = pgs[cidx];
pgs[cidx] = NULL;
uvm_pager_dropcluster(uobj, NULL, pgs, &npages, 0, 0);
simple_unlock(&uobj->vmobjlock);
UVMHIST_LOG(ubchist, "cleared pages",0,0,0,0);
goto out; goto out;
} }


/* adjust physical blkno for partial blocks */ /* adjust physical blkno for partial blocks */
bp->b_blkno += (offset - lblktosize(fs, bp->b_lblkno)) >> DEV_BSHIFT; bp->b_blkno += (offset - lblktosize(fs, bp->b_lblkno)) >> DEV_BSHIFT;

UVMHIST_LOG(ubchist, "vp %p bp %p lblkno 0x%x blkno 0x%x",
UVMHIST_LOG(ubchist, "vp %p lblkno 0x%x blkno 0x%x", vp, bp, bp->b_lblkno, bp->b_blkno);
vp, bp->b_lblkno, bp->b_blkno, 0);


/* /*
* don't bother reading the pages if we're just going to * don't bother reading the pages if we're just going to
* overwrite them. * overwrite them.
*/ */
if (ap->a_flags & PGO_OVERWRITE) { if (ap->a_flags & PGO_OVERWRITE) {

UVMHIST_LOG(ubchist, "PGO_OVERWRITE",0,0,0,0); UVMHIST_LOG(ubchist, "PGO_OVERWRITE",0,0,0,0);


/* XXX for now, zero the page */ /* XXX for now, zero the page */
if (pg->flags & PG_FAKE) { if (pg->flags & PG_FAKE) {
uvm_pagezero(pg); uvm_pagezero(pg);
pg->flags &= ~(PG_FAKE);
uvm_pageactivate(pg);
} }


UVMHIST_LOG(ubchist, "m[%d] <- pg %p", ap->a_centeridx, pg,0,0); goto out;

/* XXX what about *ap->a_count > 1 ? */
ap->a_m[ap->a_centeridx] = pg;
return VM_PAGER_OK;
} }


bp->b_bufsize = PAGE_SIZE; bp->b_bufsize = PAGE_SIZE;
Expand All @@ -416,12 +449,8 @@ UVMHIST_LOG(ubchist, "vp %p lblkno 0x%x blkno 0x%x",
min(bp->b_bufsize, fragroundup(fs, vp->v_uvm.u_size - offset)); min(bp->b_bufsize, fragroundup(fs, vp->v_uvm.u_size - offset));
bp->b_vp = vp; bp->b_vp = vp;
bp->b_flags = B_BUSY|B_READ; bp->b_flags = B_BUSY|B_READ;

UVMHIST_LOG(ubchist, "bp %p vp %p lblkno 0x%x", bp, vp, bp->b_lblkno, 0);

VOP_STRATEGY(bp); VOP_STRATEGY(bp);
error = biowait(bp); error = biowait(bp);

uvm_pagermapout((vaddr_t)bp->b_data, *ap->a_count); uvm_pagermapout((vaddr_t)bp->b_data, *ap->a_count);


out: out:
Expand All @@ -442,9 +471,7 @@ UVMHIST_LOG(ubchist, "bp %p vp %p lblkno 0x%x", bp, vp, bp->b_lblkno, 0);
uvm_pageactivate(pg); uvm_pageactivate(pg);
ap->a_m[ap->a_centeridx] = pg; ap->a_m[ap->a_centeridx] = pg;
} }

UVMHIST_LOG(ubchist, "returning, error %d", error,0,0,0); UVMHIST_LOG(ubchist, "returning, error %d", error,0,0,0);

return error ? VM_PAGER_ERROR : VM_PAGER_OK; return error ? VM_PAGER_ERROR : VM_PAGER_OK;
} }


Expand All @@ -471,7 +498,6 @@ ffs_putpages(v)
struct vnode *vp = ap->a_vp; struct vnode *vp = ap->a_vp;
struct inode *ip = VTOI(vp); struct inode *ip = VTOI(vp);
struct fs *fs = ip->i_fs; struct fs *fs = ip->i_fs;
struct ucred *cred = curproc->p_ucred; /* XXX curproc */
UVMHIST_FUNC("ffs_putpages"); UVMHIST_CALLED(ubchist); UVMHIST_FUNC("ffs_putpages"); UVMHIST_CALLED(ubchist);


pg = ap->a_m[0]; pg = ap->a_m[0];
Expand Down Expand Up @@ -513,53 +539,37 @@ ffs_putpages(v)
bp->b_flags |= B_BUSY|B_WRITE; bp->b_flags |= B_BUSY|B_WRITE;
bp->b_vp = vp; bp->b_vp = vp;


/*
* if the blkno wasn't set in the page, do a bmap to find it.
* this should only happen if the block is unallocated.
* we'll always want to set the page's blkno if it's allocated
* to help prevent memory deadlocks. we probably even want to
* allocate blocks in VOP_GETPAGES() for this same reason.
*
* once we switch to doing that, the page should always have a blkno.
* but for now, we'll handle allocating blocks here too.
*
* XXX this doesn't handle blocksizes smaller than PAGE_SIZE.
*/


bp->b_blkno = 0; bsize = blksize(fs, ip, bp->b_lblkno);
bsize = blksize(fs, ip, lblkno(fs, offset)); error = VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL);
error = ffs_balloc(ip, bp->b_lblkno, bsize, cred, NULL,
&bp->b_blkno, 0);
if (error) { if (error) {
UVMHIST_LOG(ubchist, "ffs_balloc -> %d", error, 0,0,0); UVMHIST_LOG(ubchist, "ffs_balloc -> %d", error, 0,0,0);
goto out; goto out;
} }


/* this could be ifdef DIAGNOSTIC, but it's really important */
if (bp->b_blkno == (daddr_t)-1) { if (bp->b_blkno == (daddr_t)-1) {
panic("XXX alloc from putpages vp %p", vp); panic("ffs_putpages: no backing store vp %p lbn 0x%x",
vp, bp->b_lblkno);
} }


/* adjust physical blkno for partial blocks */ /* adjust physical blkno for partial blocks */
bp->b_blkno += (offset - lblktosize(fs, bp->b_lblkno)) bp->b_blkno += (offset - lblktosize(fs, bp->b_lblkno)) >> DEV_BSHIFT;
>> DEV_BSHIFT;

UVMHIST_LOG(ubchist, "pg %p vp %p lblkno 0x%x blkno 0x%x", UVMHIST_LOG(ubchist, "pg %p vp %p lblkno 0x%x blkno 0x%x",
pg, vp, bp->b_lblkno, bp->b_blkno); pg, vp, bp->b_lblkno, bp->b_blkno);


s = splbio(); s = splbio();
vp->v_numoutput++; vp->v_numoutput++;
splx(s); splx(s);

VOP_STRATEGY(bp); VOP_STRATEGY(bp);
if (!ap->a_sync) { if (!ap->a_sync) {
return VM_PAGER_PEND; return VM_PAGER_PEND;
} }

error = biowait(bp); error = biowait(bp);


out: out:
UVMHIST_LOG(ubchist, "error %d", error,0,0,0);
uvm_pagermapout(kva, ap->a_count); uvm_pagermapout(kva, ap->a_count);
UVMHIST_LOG(ubchist, "returning, error %d", error,0,0,0);


return error ? VM_PAGER_ERROR : VM_PAGER_OK; return error ? VM_PAGER_ERROR : VM_PAGER_OK;
} }
Expand Down

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