NetBSD/sys/uvm/uvm_vnode.c

/*	$NetBSD: uvm_vnode.c,v 1.70 2006/05/14 21:38:18 elad Exp $	*/

/*
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.
 * Copyright (c) 1990 University of Utah.
 *
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Charles D. Cranor,
 *	Washington University, the University of California, Berkeley and
 *	its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)vnode_pager.c       8.8 (Berkeley) 2/13/94
 * from: Id: uvm_vnode.c,v 1.1.2.26 1998/02/02 20:38:07 chuck Exp
 */

/*
 * uvm_vnode.c: the vnode pager.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_vnode.c,v 1.70 2006/05/14 21:38:18 elad Exp $");

#include "fs_nfs.h"
#include "opt_uvmhist.h"
#include "opt_readahead.h"
#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/disklabel.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <sys/conf.h>
#include <sys/pool.h>
#include <sys/mount.h>

#include <miscfs/specfs/specdev.h>

#include <uvm/uvm.h>
#include <uvm/uvm_readahead.h>

/*
 * functions
 */

static void	uvn_detach(struct uvm_object *);
static int	uvn_get(struct uvm_object *, voff_t, struct vm_page **, int *,
			int, vm_prot_t, int, int);
static int	uvn_put(struct uvm_object *, voff_t, voff_t, int);
static void	uvn_reference(struct uvm_object *);

static int	uvn_findpage(struct uvm_object *, voff_t, struct vm_page **,
			     int);

/*
 * master pager structure
 */

struct uvm_pagerops uvm_vnodeops = {
	NULL,
	uvn_reference,
	uvn_detach,
	NULL,
	uvn_get,
	uvn_put,
};

/*
 * the ops!
 */

/*
 * uvn_attach
 *
 * attach a vnode structure to a VM object.  if the vnode is already
 * attached, then just bump the reference count by one and return the
 * VM object.   if not already attached, attach and return the new VM obj.
 * the "accessprot" tells the max access the attaching thread wants to
 * our pages.
 *
 * => caller must _not_ already be holding the lock on the uvm_object.
 * => in fact, nothing should be locked so that we can sleep here.
 * => note that uvm_object is first thing in vnode structure, so their
 *    pointers are equiv.
 */

struct uvm_object *
uvn_attach(void *arg, vm_prot_t accessprot)
{
	struct vnode *vp = arg;
	struct uvm_object *uobj = &vp->v_uobj;
	struct vattr vattr;
	const struct bdevsw *bdev;
	int result;
	struct partinfo pi;
	voff_t used_vnode_size;
	UVMHIST_FUNC("uvn_attach"); UVMHIST_CALLED(maphist);

	UVMHIST_LOG(maphist, "(vn=0x%x)", arg,0,0,0);
	used_vnode_size = (voff_t)0;

	/*
	 * first get a lock on the uobj.
	 */

	simple_lock(&uobj->vmobjlock);
	while (vp->v_flag & VXLOCK) {
		vp->v_flag |= VXWANT;
		UVMHIST_LOG(maphist, "  SLEEPING on blocked vn",0,0,0,0);
		UVM_UNLOCK_AND_WAIT(uobj, &uobj->vmobjlock, FALSE,
		    "uvn_attach", 0);
		simple_lock(&uobj->vmobjlock);
		UVMHIST_LOG(maphist,"  WOKE UP",0,0,0,0);
	}

	/*
	 * if we're mapping a BLK device, make sure it is a disk.
	 */
	if (vp->v_type == VBLK) {
		bdev = bdevsw_lookup(vp->v_rdev);
		if (bdev == NULL || bdev->d_type != D_DISK) {
			simple_unlock(&uobj->vmobjlock);
			UVMHIST_LOG(maphist,"<- done (VBLK not D_DISK!)",
				    0,0,0,0);
			return(NULL);
		}
	}
	KASSERT(vp->v_type == VREG || vp->v_type == VBLK);

	/*
	 * set up our idea of the size
	 * if this hasn't been done already.
	 */
	if (vp->v_size == VSIZENOTSET) {


	vp->v_flag |= VXLOCK;
	simple_unlock(&uobj->vmobjlock); /* drop lock in case we sleep */
		/* XXX: curproc? */
	if (vp->v_type == VBLK) {
		/*
		 * We could implement this as a specfs getattr call, but:
		 *
		 *	(1) VOP_GETATTR() would get the file system
		 *	    vnode operation, not the specfs operation.
		 *
		 *	(2) All we want is the size, anyhow.
		 */
		bdev = bdevsw_lookup(vp->v_rdev);
		if (bdev != NULL) {
			result = (*bdev->d_ioctl)(vp->v_rdev, DIOCGPART,
						  (caddr_t)&pi, FREAD, curlwp);
		} else {
			result = ENXIO;
		}
		if (result == 0) {
			/* XXX should remember blocksize */
			used_vnode_size = (voff_t)pi.disklab->d_secsize *
			    (voff_t)pi.part->p_size;
		}
	} else {
		result = VOP_GETATTR(vp, &vattr, curproc->p_cred, curlwp);
		if (result == 0)
			used_vnode_size = vattr.va_size;
	}

	/* relock object */
	simple_lock(&uobj->vmobjlock);

	if (vp->v_flag & VXWANT) {
		wakeup(vp);
	}
	vp->v_flag &= ~(VXLOCK|VXWANT);

	if (result != 0) {
		simple_unlock(&uobj->vmobjlock);
		UVMHIST_LOG(maphist,"<- done (VOP_GETATTR FAILED!)", 0,0,0,0);
		return(NULL);
	}
	vp->v_size = used_vnode_size;

	}

	simple_unlock(&uobj->vmobjlock);
	UVMHIST_LOG(maphist,"<- done, refcnt=%d", vp->v_usecount,
	    0, 0, 0);
	return uobj;
}


/*
 * uvn_reference
 *
 * duplicate a reference to a VM object.  Note that the reference
 * count must already be at least one (the passed in reference) so
 * there is no chance of the uvn being killed or locked out here.
 *
 * => caller must call with object unlocked.
 * => caller must be using the same accessprot as was used at attach time
 */

static void
uvn_reference(struct uvm_object *uobj)
{
	VREF((struct vnode *)uobj);
}


/*
 * uvn_detach
 *
 * remove a reference to a VM object.
 *
 * => caller must call with object unlocked and map locked.
 */

static void
uvn_detach(struct uvm_object *uobj)
{
	vrele((struct vnode *)uobj);
}

/*
 * uvn_put: flush page data to backing store.
 *
 * => object must be locked on entry!   VOP_PUTPAGES must unlock it.
 * => flags: PGO_SYNCIO -- use sync. I/O
 * => note: caller must set PG_CLEAN and pmap_clear_modify (if needed)
 */

static int
uvn_put(struct uvm_object *uobj, voff_t offlo, voff_t offhi, int flags)
{
	struct vnode *vp = (struct vnode *)uobj;
	int error;

	LOCK_ASSERT(simple_lock_held(&vp->v_interlock));
	error = VOP_PUTPAGES(vp, offlo, offhi, flags);
	LOCK_ASSERT(!simple_lock_held(&vp->v_interlock));
	return error;
}


/*
 * uvn_get: get pages (synchronously) from backing store
 *
 * => prefer map unlocked (not required)
 * => object must be locked!  we will _unlock_ it before starting any I/O.
 * => flags: PGO_ALLPAGES: get all of the pages
 *           PGO_LOCKED: fault data structures are locked
 * => NOTE: offset is the offset of pps[0], _NOT_ pps[centeridx]
 * => NOTE: caller must check for released pages!!
 */

static int
uvn_get(struct uvm_object *uobj, voff_t offset,
    struct vm_page **pps /* IN/OUT */,
    int *npagesp /* IN (OUT if PGO_LOCKED)*/,
    int centeridx, vm_prot_t access_type, int advice, int flags)
{
	struct vnode *vp = (struct vnode *)uobj;
	int error;
#if defined(READAHEAD_STATS)
	int orignpages = *npagesp;
#endif /* defined(READAHEAD_STATS) */

	UVMHIST_FUNC("uvn_get"); UVMHIST_CALLED(ubchist);

	UVMHIST_LOG(ubchist, "vp %p off 0x%x", vp, (int)offset, 0,0);

	if ((access_type & VM_PROT_WRITE) == 0 && (flags & PGO_LOCKED) == 0) {
		simple_unlock(&vp->v_interlock);
		vn_ra_allocctx(vp);
		uvm_ra_request(vp->v_ractx, advice, uobj, offset,
		    *npagesp << PAGE_SHIFT);
		simple_lock(&vp->v_interlock);
	}

	error = VOP_GETPAGES(vp, offset, pps, npagesp, centeridx,
			     access_type, advice, flags);

#if defined(READAHEAD_STATS)
	if (((flags & PGO_LOCKED) != 0 && *npagesp > 0) ||
	    ((flags & (PGO_LOCKED|PGO_SYNCIO)) == PGO_SYNCIO && error == 0)) {
		int i;

		if ((flags & PGO_LOCKED) == 0) {
			simple_lock(&uobj->vmobjlock);
		}
		for (i = 0; i < orignpages; i++) {
			struct vm_page *pg = pps[i];

			if (pg == NULL || pg == PGO_DONTCARE) {
				continue;
			}
			if ((pg->flags & PG_SPECULATIVE) != 0) {
				pg->flags &= ~PG_SPECULATIVE;
				uvm_ra_hit.ev_count++;
			}
		}
		if ((flags & PGO_LOCKED) == 0) {
			simple_unlock(&uobj->vmobjlock);
		}
	}
#endif /* defined(READAHEAD_STATS) */

	return error;
}


/*
 * uvn_findpages:
 * return the page for the uobj and offset requested, allocating if needed.
 * => uobj must be locked.
 * => returned pages will be BUSY.
 */

int
uvn_findpages(struct uvm_object *uobj, voff_t offset, int *npagesp,
    struct vm_page **pgs, int flags)
{
	int i, count, found, npages, rv;

	count = found = 0;
	npages = *npagesp;
	if (flags & UFP_BACKWARD) {
		for (i = npages - 1; i >= 0; i--, offset -= PAGE_SIZE) {
			rv = uvn_findpage(uobj, offset, &pgs[i], flags);
			if (rv == 0) {
				if (flags & UFP_DIRTYONLY)
					break;
			} else
				found++;
			count++;
		}
	} else {
		for (i = 0; i < npages; i++, offset += PAGE_SIZE) {
			rv = uvn_findpage(uobj, offset, &pgs[i], flags);
			if (rv == 0) {
				if (flags & UFP_DIRTYONLY)
					break;
			} else
				found++;
			count++;
		}
	}
	*npagesp = count;
	return (found);
}

static int
uvn_findpage(struct uvm_object *uobj, voff_t offset, struct vm_page **pgp,
    int flags)
{
	struct vm_page *pg;
	boolean_t dirty;
	UVMHIST_FUNC("uvn_findpage"); UVMHIST_CALLED(ubchist);
	UVMHIST_LOG(ubchist, "vp %p off 0x%lx", uobj, offset,0,0);

	if (*pgp != NULL) {
		UVMHIST_LOG(ubchist, "dontcare", 0,0,0,0);
		return 0;
	}
	for (;;) {
		/* look for an existing page */
		pg = uvm_pagelookup(uobj, offset);

		/* nope?  allocate one now */
		if (pg == NULL) {
			if (flags & UFP_NOALLOC) {
				UVMHIST_LOG(ubchist, "noalloc", 0,0,0,0);
				return 0;
			}
			pg = uvm_pagealloc(uobj, offset, NULL, 0);
			if (pg == NULL) {
				if (flags & UFP_NOWAIT) {
					UVMHIST_LOG(ubchist, "nowait",0,0,0,0);
					return 0;
				}
				simple_unlock(&uobj->vmobjlock);
				uvm_wait("uvn_fp1");
				simple_lock(&uobj->vmobjlock);
				continue;
			}
			UVMHIST_LOG(ubchist, "alloced %p", pg,0,0,0);
			break;
		} else if (flags & UFP_NOCACHE) {
			UVMHIST_LOG(ubchist, "nocache",0,0,0,0);
			return 0;
		}

		/* page is there, see if we need to wait on it */
		if ((pg->flags & PG_BUSY) != 0) {
			if (flags & UFP_NOWAIT) {
				UVMHIST_LOG(ubchist, "nowait",0,0,0,0);
				return 0;
			}
			pg->flags |= PG_WANTED;
			UVMHIST_LOG(ubchist, "wait %p", pg,0,0,0);
			UVM_UNLOCK_AND_WAIT(pg, &uobj->vmobjlock, 0,
					    "uvn_fp2", 0);
			simple_lock(&uobj->vmobjlock);
			continue;
		}

		/* skip PG_RDONLY pages if requested */
		if ((flags & UFP_NORDONLY) && (pg->flags & PG_RDONLY)) {
			UVMHIST_LOG(ubchist, "nordonly",0,0,0,0);
			return 0;
		}

		/* stop on clean pages if requested */
		if (flags & UFP_DIRTYONLY) {
			dirty = pmap_clear_modify(pg) ||
				(pg->flags & PG_CLEAN) == 0;
			pg->flags |= PG_CLEAN;
			if (!dirty) {
				UVMHIST_LOG(ubchist, "dirtonly", 0,0,0,0);
				return 0;
			}
		}

		/* mark the page BUSY and we're done. */
		pg->flags |= PG_BUSY;
		UVM_PAGE_OWN(pg, "uvn_findpage");
		UVMHIST_LOG(ubchist, "found %p", pg,0,0,0);
		break;
	}
	*pgp = pg;
	return 1;
}

/*
 * uvm_vnp_setsize: grow or shrink a vnode uobj
 *
 * grow   => just update size value
 * shrink => toss un-needed pages
 *
 * => we assume that the caller has a reference of some sort to the
 *	vnode in question so that it will not be yanked out from under
 *	us.
 */

void
uvm_vnp_setsize(struct vnode *vp, voff_t newsize)
{
	struct uvm_object *uobj = &vp->v_uobj;
	voff_t pgend = round_page(newsize);
	UVMHIST_FUNC("uvm_vnp_setsize"); UVMHIST_CALLED(ubchist);

	simple_lock(&uobj->vmobjlock);
	UVMHIST_LOG(ubchist, "vp %p old 0x%x new 0x%x",
	    vp, vp->v_size, newsize, 0);

	/*
	 * now check if the size has changed: if we shrink we had better
	 * toss some pages...
	 */

	if (vp->v_size > pgend && vp->v_size != VSIZENOTSET) {
		(void) uvn_put(uobj, pgend, 0, PGO_FREE | PGO_SYNCIO);
	} else {
		simple_unlock(&uobj->vmobjlock);
	}
	vp->v_size = newsize;
}

/*
 * uvm_vnp_zerorange:  set a range of bytes in a file to zero.
 */

void
uvm_vnp_zerorange(struct vnode *vp, off_t off, size_t len)
{
	void *win;
	int flags;

	/*
	 * XXXUBC invent kzero() and use it
	 */

	while (len) {
		vsize_t bytelen = len;

		win = ubc_alloc(&vp->v_uobj, off, &bytelen, UVM_ADV_NORMAL,
		    UBC_WRITE);
		memset(win, 0, bytelen);
		flags = UBC_WANT_UNMAP(vp) ? UBC_UNMAP : 0;
		ubc_release(win, flags);

		off += bytelen;
		len -= bytelen;
	}
}