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freebsd-src/sys/fs/specfs/spec_vnops.c
Kirk McKusick e03486d198 This checkin reimplements the io-request priority hack in a way 
that works in the new threaded kernel. It was commented out of
the disksort routine earlier this year for the reasons given in
kern/subr_disklabel.c (which is where this code used to reside
before it moved to kern/subr_disk.c):

----------------------------
revision 1.65
date: 2002/04/22 06:53:20;  author: phk;  state: Exp;  lines: +5 -0
Comment out Kirks io-request priority hack until we can do this in a
civilized way which doesn't cause grief.

The problem is that it is not generally safe to cast a "struct bio
*" to a "struct buf *".  Things like ccd, vinum, ata-raid and GEOM
constructs bio's which are not entrails of a struct buf.

Also, curthread may or may not have anything to do with the I/O request
at hand.

The correct solution can either be to tag struct bio's with a
priority derived from the requesting threads nice and have disksort
act on this field, this wouldn't address the "silly-seek syndrome"
where two equal processes bang the diskheads from one edge to the
other of the disk repeatedly.

Alternatively, and probably better: a sleep should be introduced
either at the time the I/O is requested or at the time it is completed
where we can be sure to sleep in the right thread.

The sleep also needs to be in constant timeunits, 1/hz can be practicaly
any sub-second size, at high HZ the current code practically doesn't
do anything.
----------------------------

As suggested in this comment, it is no longer located in the disk sort
routine, but rather now resides in spec_strategy where the disk operations
are being queued by the thread that is associated with the process that
is really requesting the I/O. At that point, the disk queues are not
visible, so the I/O for positively niced processes is always slowed
down whether or not there is other activity on the disk.

On the issue of scaling HZ, I believe that the current scheme is
better than using a fixed quantum of time. As machines and I/O
subsystems get faster, the resolution on the clock also rises.
So, ten years from now we will be slowing things down for shorter
periods of time, but the proportional effect on the system will
be about the same as it is today. So, I view this as a feature
rather than a drawback. Hence this patch sticks with using HZ.

Sponsored by:	DARPA & NAI Labs.
Reviewed by:	Poul-Henning Kamp <phk@critter.freebsd.dk>
2002-10-22 00:59:49 +00:00

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/*
* Copyright (c) 1989, 1993, 1995
* The Regents of the University of California. All rights reserved.
*
* 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 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.
*
* @(#)spec_vnops.c 8.14 (Berkeley) 5/21/95
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/sx.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mutex.h>
#include <sys/conf.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <sys/vmmeter.h>
#include <sys/tty.h>
#include <vm/vm.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
static int spec_advlock(struct vop_advlock_args *);
static int spec_bmap(struct vop_bmap_args *);
static int spec_close(struct vop_close_args *);
static int spec_freeblks(struct vop_freeblks_args *);
static int spec_fsync(struct vop_fsync_args *);
static int spec_getpages(struct vop_getpages_args *);
static int spec_ioctl(struct vop_ioctl_args *);
static int spec_kqfilter(struct vop_kqfilter_args *);
static int spec_open(struct vop_open_args *);
static int spec_poll(struct vop_poll_args *);
static int spec_print(struct vop_print_args *);
static int spec_read(struct vop_read_args *);
static int spec_strategy(struct vop_strategy_args *);
static int spec_write(struct vop_write_args *);
vop_t **spec_vnodeop_p;
static struct vnodeopv_entry_desc spec_vnodeop_entries[] = {
{ &vop_default_desc, (vop_t *) vop_defaultop },
{ &vop_access_desc, (vop_t *) vop_ebadf },
{ &vop_advlock_desc, (vop_t *) spec_advlock },
{ &vop_bmap_desc, (vop_t *) spec_bmap },
{ &vop_close_desc, (vop_t *) spec_close },
{ &vop_create_desc, (vop_t *) vop_panic },
{ &vop_freeblks_desc, (vop_t *) spec_freeblks },
{ &vop_fsync_desc, (vop_t *) spec_fsync },
{ &vop_getpages_desc, (vop_t *) spec_getpages },
{ &vop_getwritemount_desc, (vop_t *) vop_stdgetwritemount },
{ &vop_ioctl_desc, (vop_t *) spec_ioctl },
{ &vop_kqfilter_desc, (vop_t *) spec_kqfilter },
{ &vop_lease_desc, (vop_t *) vop_null },
{ &vop_link_desc, (vop_t *) vop_panic },
{ &vop_mkdir_desc, (vop_t *) vop_panic },
{ &vop_mknod_desc, (vop_t *) vop_panic },
{ &vop_open_desc, (vop_t *) spec_open },
{ &vop_pathconf_desc, (vop_t *) vop_stdpathconf },
{ &vop_poll_desc, (vop_t *) spec_poll },
{ &vop_print_desc, (vop_t *) spec_print },
{ &vop_read_desc, (vop_t *) spec_read },
{ &vop_readdir_desc, (vop_t *) vop_panic },
{ &vop_readlink_desc, (vop_t *) vop_panic },
{ &vop_reallocblks_desc, (vop_t *) vop_panic },
{ &vop_reclaim_desc, (vop_t *) vop_null },
{ &vop_remove_desc, (vop_t *) vop_panic },
{ &vop_rename_desc, (vop_t *) vop_panic },
{ &vop_rmdir_desc, (vop_t *) vop_panic },
{ &vop_setattr_desc, (vop_t *) vop_ebadf },
{ &vop_strategy_desc, (vop_t *) spec_strategy },
{ &vop_symlink_desc, (vop_t *) vop_panic },
{ &vop_write_desc, (vop_t *) spec_write },
{ &vop_lock_desc, (vop_t *) vop_nolock },
{ &vop_unlock_desc, (vop_t *) vop_nounlock },
{ &vop_islocked_desc, (vop_t *) vop_noislocked },
{ NULL, NULL }
};
static struct vnodeopv_desc spec_vnodeop_opv_desc =
{ &spec_vnodeop_p, spec_vnodeop_entries };
VNODEOP_SET(spec_vnodeop_opv_desc);
int
spec_vnoperate(ap)
struct vop_generic_args /* {
struct vnodeop_desc *a_desc;
<other random data follows, presumably>
} */ *ap;
{
return (VOCALL(spec_vnodeop_p, ap->a_desc->vdesc_offset, ap));
}
static void spec_getpages_iodone(struct buf *bp);
/*
* Open a special file.
*/
/* ARGSUSED */
static int
spec_open(ap)
struct vop_open_args /* {
struct vnode *a_vp;
int a_mode;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
struct thread *td = ap->a_td;
struct vnode *vp = ap->a_vp;
dev_t dev = vp->v_rdev;
int error;
struct cdevsw *dsw;
const char *cp;
if (vp->v_type == VBLK)
return (ENXIO);
/* Don't allow open if fs is mounted -nodev. */
if (vp->v_mount && (vp->v_mount->mnt_flag & MNT_NODEV))
return (ENXIO);
dsw = devsw(dev);
if (dsw == NULL || dsw->d_open == NULL)
return (ENXIO);
/* Make this field valid before any I/O in d_open. */
if (dev->si_iosize_max == 0)
dev->si_iosize_max = DFLTPHYS;
/*
* XXX: Disks get special billing here, but it is mostly wrong.
* XXX: Disk partitions can overlap and the real checks should
* XXX: take this into account, and consequently they need to
* XXX: live in the disk slice code. Some checks do.
*/
if (vn_isdisk(vp, NULL) && ap->a_cred != FSCRED &&
(ap->a_mode & FWRITE)) {
/*
* Never allow opens for write if the disk is mounted R/W.
*/
if (vp->v_rdev->si_mountpoint != NULL &&
!(vp->v_rdev->si_mountpoint->mnt_flag & MNT_RDONLY))
return (EBUSY);
/*
* When running in secure mode, do not allow opens
* for writing if the disk is mounted.
*/
error = securelevel_ge(td->td_ucred, 1);
if (error && vfs_mountedon(vp))
return (error);
/*
* When running in very secure mode, do not allow
* opens for writing of any disks.
*/
error = securelevel_ge(td->td_ucred, 2);
if (error)
return (error);
}
/* XXX: Special casing of ttys for deadfs. Probably redundant. */
if (dsw->d_flags & D_TTY)
vp->v_vflag |= VV_ISTTY;
VOP_UNLOCK(vp, 0, td);
if(dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_open(dev, ap->a_mode, S_IFCHR, td);
PICKUP_GIANT();
} else
error = dsw->d_open(dev, ap->a_mode, S_IFCHR, td);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (error)
return (error);
if (dsw->d_flags & D_TTY) {
if (dev->si_tty) {
struct tty *tp;
tp = dev->si_tty;
if (!tp->t_stop) {
printf("Warning:%s: no t_stop, using nottystop\n", devtoname(dev));
tp->t_stop = nottystop;
}
}
}
if (vn_isdisk(vp, NULL)) {
if (!dev->si_bsize_phys)
dev->si_bsize_phys = DEV_BSIZE;
}
if ((dsw->d_flags & D_DISK) == 0) {
cp = devtoname(dev);
if (*cp == '#' && (dsw->d_flags & D_NAGGED) == 0) {
printf("WARNING: driver %s should register devices with make_dev() (dev_t = \"%s\")\n",
dsw->d_name, cp);
dsw->d_flags |= D_NAGGED;
}
}
return (error);
}
/*
* Vnode op for read
*/
/* ARGSUSED */
static int
spec_read(ap)
struct vop_read_args /* {
struct vnode *a_vp;
struct uio *a_uio;
int a_ioflag;
struct ucred *a_cred;
} */ *ap;
{
struct vnode *vp;
struct thread *td;
struct uio *uio;
dev_t dev;
int error, resid;
struct cdevsw *dsw;
vp = ap->a_vp;
dev = vp->v_rdev;
uio = ap->a_uio;
td = uio->uio_td;
resid = uio->uio_resid;
if (resid == 0)
return (0);
dsw = devsw(dev);
VOP_UNLOCK(vp, 0, td);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_read(dev, uio, ap->a_ioflag);
PICKUP_GIANT();
} else
error = dsw->d_read(dev, uio, ap->a_ioflag);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (uio->uio_resid != resid || (error == 0 && resid != 0))
vfs_timestamp(&dev->si_atime);
return (error);
}
/*
* Vnode op for write
*/
/* ARGSUSED */
static int
spec_write(ap)
struct vop_write_args /* {
struct vnode *a_vp;
struct uio *a_uio;
int a_ioflag;
struct ucred *a_cred;
} */ *ap;
{
struct vnode *vp;
struct thread *td;
struct uio *uio;
dev_t dev;
int error, resid;
struct cdevsw *dsw;
vp = ap->a_vp;
dev = vp->v_rdev;
dsw = devsw(dev);
uio = ap->a_uio;
td = uio->uio_td;
resid = uio->uio_resid;
VOP_UNLOCK(vp, 0, td);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_write(dev, uio, ap->a_ioflag);
PICKUP_GIANT();
} else
error = dsw->d_write(dev, uio, ap->a_ioflag);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (uio->uio_resid != resid || (error == 0 && resid != 0)) {
vfs_timestamp(&dev->si_ctime);
dev->si_mtime = dev->si_ctime;
}
return (error);
}
/*
* Device ioctl operation.
*/
/* ARGSUSED */
static int
spec_ioctl(ap)
struct vop_ioctl_args /* {
struct vnode *a_vp;
u_long a_command;
caddr_t a_data;
int a_fflag;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
dev_t dev;
int error;
struct cdevsw *dsw;
dev = ap->a_vp->v_rdev;
dsw = devsw(dev);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_ioctl(dev, ap->a_command,
ap->a_data, ap->a_fflag, ap->a_td);
PICKUP_GIANT();
} else
error = dsw->d_ioctl(dev, ap->a_command,
ap->a_data, ap->a_fflag, ap->a_td);
if (error == ENOIOCTL)
error = ENOTTY;
return (error);
}
/* ARGSUSED */
static int
spec_poll(ap)
struct vop_poll_args /* {
struct vnode *a_vp;
int a_events;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
dev_t dev;
struct cdevsw *dsw;
int error;
dev = ap->a_vp->v_rdev;
dsw = devsw(dev);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_poll(dev, ap->a_events, ap->a_td);
PICKUP_GIANT();
} else
error = dsw->d_poll(dev, ap->a_events, ap->a_td);
return(error);
}
/* ARGSUSED */
static int
spec_kqfilter(ap)
struct vop_kqfilter_args /* {
struct vnode *a_vp;
struct knote *a_kn;
} */ *ap;
{
dev_t dev;
struct cdevsw *dsw;
int error;
dev = ap->a_vp->v_rdev;
dsw = devsw(dev);
if (!(dsw->d_flags & D_KQFILTER))
return (1);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_kqfilter(dev, ap->a_kn);
PICKUP_GIANT();
} else
error = dsw->d_kqfilter(dev, ap->a_kn);
return (error);
}
/*
* Synch buffers associated with a block device
*/
/* ARGSUSED */
static int
spec_fsync(ap)
struct vop_fsync_args /* {
struct vnode *a_vp;
struct ucred *a_cred;
int a_waitfor;
struct thread *a_td;
} */ *ap;
{
struct vnode *vp = ap->a_vp;
struct buf *bp;
struct buf *nbp;
int s;
int maxretry = 10000; /* large, arbitrarily chosen */
if (!vn_isdisk(vp, NULL))
return (0);
VI_LOCK(vp);
loop1:
/*
* MARK/SCAN initialization to avoid infinite loops.
*/
s = splbio();
TAILQ_FOREACH(bp, &vp->v_dirtyblkhd, b_vnbufs) {
bp->b_flags &= ~B_SCANNED;
}
splx(s);
/*
* Flush all dirty buffers associated with a block device.
*/
loop2:
s = splbio();
for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp != NULL; bp = nbp) {
nbp = TAILQ_NEXT(bp, b_vnbufs);
if ((bp->b_flags & B_SCANNED) != 0)
continue;
VI_UNLOCK(vp);
bp->b_flags |= B_SCANNED;
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
VI_LOCK(vp);
continue;
}
if ((bp->b_flags & B_DELWRI) == 0)
panic("spec_fsync: not dirty");
if ((vp->v_vflag & VV_OBJBUF) && (bp->b_flags & B_CLUSTEROK)) {
BUF_UNLOCK(bp);
vfs_bio_awrite(bp);
splx(s);
} else {
bremfree(bp);
splx(s);
bawrite(bp);
}
VI_LOCK(vp);
goto loop2;
}
/*
* If synchronous the caller expects us to completely resolve all
* dirty buffers in the system. Wait for in-progress I/O to
* complete (which could include background bitmap writes), then
* retry if dirty blocks still exist.
*/
if (ap->a_waitfor == MNT_WAIT) {
while (vp->v_numoutput) {
vp->v_iflag |= VI_BWAIT;
msleep((caddr_t)&vp->v_numoutput, VI_MTX(vp),
PRIBIO + 1, "spfsyn", 0);
}
if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
if (--maxretry != 0) {
splx(s);
goto loop1;
}
vprint("spec_fsync: giving up on dirty", vp);
}
}
VI_UNLOCK(vp);
splx(s);
return (0);
}
/*
* Mutex to use when delaying niced I/O bound processes in spec_strategy().
*/
static struct mtx strategy_mtx;
static void
strategy_init(void)
{
mtx_init(&strategy_mtx, "strategy", NULL, MTX_DEF);
}
SYSINIT(strategy, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, strategy_init, NULL)
/*
* Just call the device strategy routine
*/
static int
spec_strategy(ap)
struct vop_strategy_args /* {
struct vnode *a_vp;
struct buf *a_bp;
} */ *ap;
{
struct buf *bp;
struct vnode *vp;
struct mount *mp;
int error;
struct cdevsw *dsw;
struct thread *td = curthread;
/*
* Slow down disk requests for niced processes.
*/
if (td && td->td_ksegrp->kg_nice > 0) {
mtx_lock(&strategy_mtx);
msleep(&strategy_mtx, &strategy_mtx,
PPAUSE | PCATCH | PDROP, "ioslow",
td->td_ksegrp->kg_nice);
}
bp = ap->a_bp;
vp = ap->a_vp;
if (bp->b_iocmd == BIO_WRITE) {
if ((bp->b_flags & B_VALIDSUSPWRT) == 0 &&
bp->b_vp != NULL && bp->b_vp->v_mount != NULL &&
(bp->b_vp->v_mount->mnt_kern_flag & MNTK_SUSPENDED) != 0)
panic("spec_strategy: bad I/O");
bp->b_flags &= ~B_VALIDSUSPWRT;
if (LIST_FIRST(&bp->b_dep) != NULL)
buf_start(bp);
mp_fixme("This should require the vnode lock.");
if ((vp->v_vflag & VV_COPYONWRITE) &&
vp->v_rdev->si_copyonwrite &&
(error = (*vp->v_rdev->si_copyonwrite)(vp, bp)) != 0 &&
error != EOPNOTSUPP) {
bp->b_io.bio_error = error;
bp->b_io.bio_flags |= BIO_ERROR;
biodone(&bp->b_io);
return (0);
}
}
/*
* Collect statistics on synchronous and asynchronous read
* and write counts for disks that have associated filesystems.
*/
if (vn_isdisk(vp, NULL) && (mp = vp->v_rdev->si_mountpoint) != NULL) {
if (bp->b_iocmd == BIO_WRITE) {
if (bp->b_lock.lk_lockholder == LK_KERNPROC)
mp->mnt_stat.f_asyncwrites++;
else
mp->mnt_stat.f_syncwrites++;
} else {
if (bp->b_lock.lk_lockholder == LK_KERNPROC)
mp->mnt_stat.f_asyncreads++;
else
mp->mnt_stat.f_syncreads++;
}
}
if (devsw(bp->b_dev) == NULL) {
bp->b_io.bio_error = ENXIO;
bp->b_io.bio_flags |= BIO_ERROR;
biodone(&bp->b_io);
return (0);
}
dsw = devsw(bp->b_dev);
KASSERT(dsw->d_strategy != NULL,
("No strategy on dev %s responsible for buffer %p\n",
devtoname(bp->b_dev), bp));
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
DEV_STRATEGY(bp, 0);
PICKUP_GIANT();
} else
DEV_STRATEGY(bp, 0);
return (0);
}
static int
spec_freeblks(ap)
struct vop_freeblks_args /* {
struct vnode *a_vp;
daddr_t a_addr;
daddr_t a_length;
} */ *ap;
{
struct cdevsw *bsw;
struct buf *bp;
/*
* XXX: This assumes that strategy does the deed right away.
* XXX: this may not be TRTTD.
*/
bsw = devsw(ap->a_vp->v_rdev);
if ((bsw->d_flags & D_CANFREE) == 0)
return (0);
bp = geteblk(ap->a_length);
bp->b_iocmd = BIO_DELETE;
bp->b_dev = ap->a_vp->v_rdev;
bp->b_blkno = ap->a_addr;
bp->b_offset = dbtob(ap->a_addr);
bp->b_bcount = ap->a_length;
BUF_KERNPROC(bp);
DEV_STRATEGY(bp, 0);
return (0);
}
/*
* Implement degenerate case where the block requested is the block
* returned, and assume that the entire device is contiguous in regards
* to the contiguous block range (runp and runb).
*/
static int
spec_bmap(ap)
struct vop_bmap_args /* {
struct vnode *a_vp;
daddr_t a_bn;
struct vnode **a_vpp;
daddr_t *a_bnp;
int *a_runp;
int *a_runb;
} */ *ap;
{
struct vnode *vp = ap->a_vp;
int runp = 0;
int runb = 0;
if (ap->a_vpp != NULL)
*ap->a_vpp = vp;
if (ap->a_bnp != NULL)
*ap->a_bnp = ap->a_bn;
if (vp->v_mount != NULL)
runp = runb = MAXBSIZE / vp->v_mount->mnt_stat.f_iosize;
if (ap->a_runp != NULL)
*ap->a_runp = runp;
if (ap->a_runb != NULL)
*ap->a_runb = runb;
return (0);
}
/*
* Device close routine
*/
/* ARGSUSED */
static int
spec_close(ap)
struct vop_close_args /* {
struct vnode *a_vp;
int a_fflag;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
struct vnode *vp = ap->a_vp, *oldvp;
struct thread *td = ap->a_td;
dev_t dev = vp->v_rdev;
struct cdevsw *dsw;
int error;
/*
* Hack: a tty device that is a controlling terminal
* has a reference from the session structure.
* We cannot easily tell that a character device is
* a controlling terminal, unless it is the closing
* process' controlling terminal. In that case,
* if the reference count is 2 (this last descriptor
* plus the session), release the reference from the session.
*/
/*
* This needs to be rewritten to take the vp interlock into
* consideration.
*/
dsw = devsw(dev);
oldvp = NULL;
sx_xlock(&proctree_lock);
if (td && vp == td->td_proc->p_session->s_ttyvp) {
SESS_LOCK(td->td_proc->p_session);
VI_LOCK(vp);
if (vcount(vp) == 2 && (vp->v_iflag & VI_XLOCK) == 0) {
td->td_proc->p_session->s_ttyvp = NULL;
oldvp = vp;
}
VI_UNLOCK(vp);
SESS_UNLOCK(td->td_proc->p_session);
}
sx_xunlock(&proctree_lock);
if (oldvp != NULL)
vrele(oldvp);
/*
* We do not want to really close the device if it
* is still in use unless we are trying to close it
* forcibly. Since every use (buffer, vnode, swap, cmap)
* holds a reference to the vnode, and because we mark
* any other vnodes that alias this device, when the
* sum of the reference counts on all the aliased
* vnodes descends to one, we are on last close.
*/
VI_LOCK(vp);
if (vp->v_iflag & VI_XLOCK) {
/* Forced close. */
} else if (dsw->d_flags & D_TRACKCLOSE) {
/* Keep device updated on status. */
} else if (vcount(vp) > 1) {
VI_UNLOCK(vp);
return (0);
}
VI_UNLOCK(vp);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_close(dev, ap->a_fflag, S_IFCHR, td);
PICKUP_GIANT();
} else
error = dsw->d_close(dev, ap->a_fflag, S_IFCHR, td);
return (error);
}
/*
* Print out the contents of a special device vnode.
*/
static int
spec_print(ap)
struct vop_print_args /* {
struct vnode *a_vp;
} */ *ap;
{
printf("tag %s, dev %s\n", ap->a_vp->v_tag,
devtoname(ap->a_vp->v_rdev));
return (0);
}
/*
* Special device advisory byte-level locks.
*/
/* ARGSUSED */
static int
spec_advlock(ap)
struct vop_advlock_args /* {
struct vnode *a_vp;
caddr_t a_id;
int a_op;
struct flock *a_fl;
int a_flags;
} */ *ap;
{
return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
}
static void
spec_getpages_iodone(bp)
struct buf *bp;
{
bp->b_flags |= B_DONE;
wakeup(bp);
}
static int
spec_getpages(ap)
struct vop_getpages_args *ap;
{
vm_offset_t kva;
int error;
int i, pcount, size, s;
daddr_t blkno;
struct buf *bp;
vm_page_t m;
vm_ooffset_t offset;
int toff, nextoff, nread;
struct vnode *vp = ap->a_vp;
int blksiz;
int gotreqpage;
GIANT_REQUIRED;
error = 0;
pcount = round_page(ap->a_count) / PAGE_SIZE;
/*
* Calculate the offset of the transfer and do a sanity check.
* FreeBSD currently only supports an 8 TB range due to b_blkno
* being in DEV_BSIZE ( usually 512 ) byte chunks on call to
* VOP_STRATEGY. XXX
*/
offset = IDX_TO_OFF(ap->a_m[0]->pindex) + ap->a_offset;
blkno = btodb(offset);
/*
* Round up physical size for real devices. We cannot round using
* v_mount's block size data because v_mount has nothing to do with
* the device. i.e. it's usually '/dev'. We need the physical block
* size for the device itself.
*
* We can't use v_rdev->si_mountpoint because it only exists when the
* block device is mounted. However, we can use v_rdev.
*/
if (vn_isdisk(vp, NULL))
blksiz = vp->v_rdev->si_bsize_phys;
else
blksiz = DEV_BSIZE;
size = (ap->a_count + blksiz - 1) & ~(blksiz - 1);
bp = getpbuf(NULL);
kva = (vm_offset_t)bp->b_data;
/*
* Map the pages to be read into the kva.
*/
pmap_qenter(kva, ap->a_m, pcount);
/* Build a minimal buffer header. */
bp->b_iocmd = BIO_READ;
bp->b_iodone = spec_getpages_iodone;
/* B_PHYS is not set, but it is nice to fill this in. */
KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
bp->b_rcred = crhold(curthread->td_ucred);
bp->b_wcred = crhold(curthread->td_ucred);
bp->b_blkno = blkno;
bp->b_lblkno = blkno;
pbgetvp(ap->a_vp, bp);
bp->b_bcount = size;
bp->b_bufsize = size;
bp->b_resid = 0;
bp->b_runningbufspace = bp->b_bufsize;
runningbufspace += bp->b_runningbufspace;
cnt.v_vnodein++;
cnt.v_vnodepgsin += pcount;
/* Do the input. */
BUF_STRATEGY(bp);
s = splbio();
/* We definitely need to be at splbio here. */
while ((bp->b_flags & B_DONE) == 0)
tsleep(bp, PVM, "spread", 0);
splx(s);
if ((bp->b_ioflags & BIO_ERROR) != 0) {
if (bp->b_error)
error = bp->b_error;
else
error = EIO;
}
nread = size - bp->b_resid;
if (nread < ap->a_count) {
bzero((caddr_t)kva + nread,
ap->a_count - nread);
}
pmap_qremove(kva, pcount);
gotreqpage = 0;
vm_page_lock_queues();
for (i = 0, toff = 0; i < pcount; i++, toff = nextoff) {
nextoff = toff + PAGE_SIZE;
m = ap->a_m[i];
m->flags &= ~PG_ZERO;
if (nextoff <= nread) {
m->valid = VM_PAGE_BITS_ALL;
vm_page_undirty(m);
} else if (toff < nread) {
/*
* Since this is a VM request, we have to supply the
* unaligned offset to allow vm_page_set_validclean()
* to zero sub-DEV_BSIZE'd portions of the page.
*/
vm_page_set_validclean(m, 0, nread - toff);
} else {
m->valid = 0;
vm_page_undirty(m);
}
if (i != ap->a_reqpage) {
/*
* Just in case someone was asking for this page we
* now tell them that it is ok to use.
*/
if (!error || (m->valid == VM_PAGE_BITS_ALL)) {
if (m->valid) {
if (m->flags & PG_WANTED) {
vm_page_activate(m);
} else {
vm_page_deactivate(m);
}
vm_page_wakeup(m);
} else {
vm_page_free(m);
}
} else {
vm_page_free(m);
}
} else if (m->valid) {
gotreqpage = 1;
/*
* Since this is a VM request, we need to make the
* entire page presentable by zeroing invalid sections.
*/
if (m->valid != VM_PAGE_BITS_ALL)
vm_page_zero_invalid(m, FALSE);
}
}
vm_page_unlock_queues();
if (!gotreqpage) {
m = ap->a_m[ap->a_reqpage];
printf(
"spec_getpages:(%s) I/O read failure: (error=%d) bp %p vp %p\n",
devtoname(bp->b_dev), error, bp, bp->b_vp);
printf(
" size: %d, resid: %ld, a_count: %d, valid: 0x%x\n",
size, bp->b_resid, ap->a_count, m->valid);
printf(
" nread: %d, reqpage: %d, pindex: %lu, pcount: %d\n",
nread, ap->a_reqpage, (u_long)m->pindex, pcount);
/*
* Free the buffer header back to the swap buffer pool.
*/
relpbuf(bp, NULL);
return VM_PAGER_ERROR;
}
/*
* Free the buffer header back to the swap buffer pool.
*/
relpbuf(bp, NULL);
return VM_PAGER_OK;
}
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