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ac2b067b9a
freebsd/sys/kern/vfs_vnops.c
Kirk McKusick 9b97113391 This patch corrects the first round of panics and hangs reported 
with the new snapshot code.

Update addaliasu to correctly implement the semantics of the old
checkalias function. When a device vnode first comes into existence,
check to see if an anonymous vnode for the same device was created
at boot time by bdevvp(). If so, adopt the bdevvp vnode rather than
creating a new vnode for the device. This corrects a problem which
caused the kernel to panic when taking a snapshot of the root
filesystem.

Change the calling convention of vn_write_suspend_wait() to be the
same as vn_start_write().

Split out softdep_flushworklist() from softdep_flushfiles() so that
it can be used to clear the work queue when suspending filesystem
operations.

Access to buffers becomes recursive so that snapshots can recursively
traverse their indirect blocks using ffs_copyonwrite() when checking
for the need for copy on write when flushing one of their own indirect
blocks. This eliminates a deadlock between the syncer daemon and a
process taking a snapshot.

Ensure that softdep_process_worklist() can never block because of a
snapshot being taken. This eliminates a problem with buffer starvation.

Cleanup change in ffs_sync() which did not synchronously wait when
MNT_WAIT was specified. The result was an unclean filesystem panic
when doing forcible unmount with heavy filesystem I/O in progress.

Return a zero'ed block when reading a block that was not in use at
the time that a snapshot was taken. Normally, these blocks should
never be read. However, the readahead code will occationally read
them which can cause unexpected behavior.

Clean up the debugging code that ensures that no blocks be written
on a filesystem while it is suspended. Snapshots must explicitly
label the blocks that they are writing during the suspension so that
they do not cause a `write on suspended filesystem' panic.

Reorganize ffs_copyonwrite() to eliminate a deadlock and also to
prevent a race condition that would permit the same block to be
copied twice. This change eliminates an unexpected soft updates
inconsistency in fsck caused by the double allocation.

Use bqrelse rather than brelse for buffers that will be needed
soon again by the snapshot code. This improves snapshot performance.
2000-07-24 05:28:33 +00:00

876 lines
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/*
* 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
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* 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.
*
* @(#)vfs_vnops.c 8.2 (Berkeley) 1/21/94
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/filio.h>
#include <sys/ttycom.h>
#include <sys/conf.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
static int vn_closefile __P((struct file *fp, struct proc *p));
static int vn_ioctl __P((struct file *fp, u_long com, caddr_t data,
struct proc *p));
static int vn_read __P((struct file *fp, struct uio *uio,
struct ucred *cred, int flags, struct proc *p));
static int vn_poll __P((struct file *fp, int events, struct ucred *cred,
struct proc *p));
static int vn_statfile __P((struct file *fp, struct stat *sb, struct proc *p));
static int vn_write __P((struct file *fp, struct uio *uio,
struct ucred *cred, int flags, struct proc *p));
struct fileops vnops =
{ vn_read, vn_write, vn_ioctl, vn_poll, vn_statfile, vn_closefile };
static int filt_nullattach(struct knote *kn);
static int filt_vnattach(struct knote *kn);
static void filt_vndetach(struct knote *kn);
static int filt_vnode(struct knote *kn, long hint);
static int filt_vnread(struct knote *kn, long hint);
struct filterops vn_filtops =
{ 1, filt_vnattach, filt_vndetach, filt_vnode };
/*
* XXX
* filt_vnread is ufs-specific, so the attach routine should really
* switch out to different filterops based on the vn filetype
*/
struct filterops vn_rwfiltops[] = {
{ 1, filt_vnattach, filt_vndetach, filt_vnread },
{ 1, filt_nullattach, NULL, NULL },
};
/*
* Common code for vnode open operations.
* Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
*
* Note that this does NOT free nameidata for the successful case,
* due to the NDINIT being done elsewhere.
*/
int
vn_open(ndp, flagp, cmode)
register struct nameidata *ndp;
int *flagp, cmode;
{
struct vnode *vp;
struct mount *mp;
struct proc *p = ndp->ni_cnd.cn_proc;
struct ucred *cred = p->p_ucred;
struct vattr vat;
struct vattr *vap = &vat;
int mode, fmode, error;
restart:
fmode = *flagp;
if (fmode & O_CREAT) {
ndp->ni_cnd.cn_nameiop = CREATE;
ndp->ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF;
if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
ndp->ni_cnd.cn_flags |= FOLLOW;
bwillwrite();
if ((error = namei(ndp)) != 0)
return (error);
if (ndp->ni_vp == NULL) {
VATTR_NULL(vap);
vap->va_type = VREG;
vap->va_mode = cmode;
if (fmode & O_EXCL)
vap->va_vaflags |= VA_EXCLUSIVE;
if (vn_start_write(ndp->ni_dvp, &mp, V_NOWAIT) != 0) {
NDFREE(ndp, NDF_ONLY_PNBUF);
vput(ndp->ni_dvp);
if ((error = vn_start_write(NULL, &mp,
V_XSLEEP | PCATCH)) != 0)
return (error);
goto restart;
}
VOP_LEASE(ndp->ni_dvp, p, cred, LEASE_WRITE);
error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp,
&ndp->ni_cnd, vap);
vput(ndp->ni_dvp);
vn_finished_write(mp);
if (error) {
NDFREE(ndp, NDF_ONLY_PNBUF);
return (error);
}
ASSERT_VOP_UNLOCKED(ndp->ni_dvp, "create");
ASSERT_VOP_LOCKED(ndp->ni_vp, "create");
fmode &= ~O_TRUNC;
vp = ndp->ni_vp;
} else {
if (ndp->ni_dvp == ndp->ni_vp)
vrele(ndp->ni_dvp);
else
vput(ndp->ni_dvp);
ndp->ni_dvp = NULL;
vp = ndp->ni_vp;
if (fmode & O_EXCL) {
error = EEXIST;
goto bad;
}
fmode &= ~O_CREAT;
}
} else {
ndp->ni_cnd.cn_nameiop = LOOKUP;
ndp->ni_cnd.cn_flags =
((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
if ((error = namei(ndp)) != 0)
return (error);
vp = ndp->ni_vp;
}
if (vp->v_type == VLNK) {
error = EMLINK;
goto bad;
}
if (vp->v_type == VSOCK) {
error = EOPNOTSUPP;
goto bad;
}
if ((fmode & O_CREAT) == 0) {
mode = 0;
if (fmode & (FWRITE | O_TRUNC)) {
if (vp->v_type == VDIR) {
error = EISDIR;
goto bad;
}
error = vn_writechk(vp);
if (error)
goto bad;
mode |= VWRITE;
}
if (fmode & FREAD)
mode |= VREAD;
if (mode) {
error = VOP_ACCESS(vp, mode, cred, p);
if (error)
goto bad;
}
}
if ((error = VOP_OPEN(vp, fmode, cred, p)) != 0)
goto bad;
/*
* Make sure that a VM object is created for VMIO support.
*/
if (vn_canvmio(vp) == TRUE) {
if ((error = vfs_object_create(vp, p, cred)) != 0)
goto bad;
}
if (fmode & FWRITE)
vp->v_writecount++;
*flagp = fmode;
return (0);
bad:
NDFREE(ndp, NDF_ONLY_PNBUF);
vput(vp);
*flagp = fmode;
return (error);
}
/*
* Check for write permissions on the specified vnode.
* Prototype text segments cannot be written.
*/
int
vn_writechk(vp)
register struct vnode *vp;
{
/*
* If there's shared text associated with
* the vnode, try to free it up once. If
* we fail, we can't allow writing.
*/
if (vp->v_flag & VTEXT)
return (ETXTBSY);
return (0);
}
/*
* Vnode close call
*/
int
vn_close(vp, flags, cred, p)
register struct vnode *vp;
int flags;
struct ucred *cred;
struct proc *p;
{
int error;
if (flags & FWRITE)
vp->v_writecount--;
error = VOP_CLOSE(vp, flags, cred, p);
vrele(vp);
return (error);
}
static __inline
int
sequential_heuristic(struct uio *uio, struct file *fp)
{
/*
* Sequential heuristic - detect sequential operation
*/
if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
uio->uio_offset == fp->f_nextoff) {
/*
* XXX we assume that the filesystem block size is
* the default. Not true, but still gives us a pretty
* good indicator of how sequential the read operations
* are.
*/
fp->f_seqcount += (uio->uio_resid + BKVASIZE - 1) / BKVASIZE;
if (fp->f_seqcount >= 127)
fp->f_seqcount = 127;
return(fp->f_seqcount << 16);
}
/*
* Not sequential, quick draw-down of seqcount
*/
if (fp->f_seqcount > 1)
fp->f_seqcount = 1;
else
fp->f_seqcount = 0;
return(0);
}
/*
* Package up an I/O request on a vnode into a uio and do it.
*/
int
vn_rdwr(rw, vp, base, len, offset, segflg, ioflg, cred, aresid, p)
enum uio_rw rw;
struct vnode *vp;
caddr_t base;
int len;
off_t offset;
enum uio_seg segflg;
int ioflg;
struct ucred *cred;
int *aresid;
struct proc *p;
{
struct uio auio;
struct iovec aiov;
struct mount *mp;
int error;
if ((ioflg & IO_NODELOCKED) == 0) {
mp = NULL;
if (rw == UIO_WRITE &&
vp->v_type != VCHR && vp->v_type != VBLK &&
(error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) != 0)
return (error);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
}
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
aiov.iov_base = base;
aiov.iov_len = len;
auio.uio_resid = len;
auio.uio_offset = offset;
auio.uio_segflg = segflg;
auio.uio_rw = rw;
auio.uio_procp = p;
if (rw == UIO_READ) {
error = VOP_READ(vp, &auio, ioflg, cred);
} else {
error = VOP_WRITE(vp, &auio, ioflg, cred);
}
if (aresid)
*aresid = auio.uio_resid;
else
if (auio.uio_resid && error == 0)
error = EIO;
if ((ioflg & IO_NODELOCKED) == 0) {
vn_finished_write(mp);
VOP_UNLOCK(vp, 0, p);
}
return (error);
}
/*
* File table vnode read routine.
*/
static int
vn_read(fp, uio, cred, flags, p)
struct file *fp;
struct uio *uio;
struct ucred *cred;
struct proc *p;
int flags;
{
struct vnode *vp;
int error, ioflag;
KASSERT(uio->uio_procp == p, ("uio_procp %p is not p %p",
uio->uio_procp, p));
vp = (struct vnode *)fp->f_data;
ioflag = 0;
if (fp->f_flag & FNONBLOCK)
ioflag |= IO_NDELAY;
VOP_LEASE(vp, p, cred, LEASE_READ);
vn_lock(vp, LK_SHARED | LK_NOPAUSE | LK_RETRY, p);
if ((flags & FOF_OFFSET) == 0)
uio->uio_offset = fp->f_offset;
ioflag |= sequential_heuristic(uio, fp);
error = VOP_READ(vp, uio, ioflag, cred);
if ((flags & FOF_OFFSET) == 0)
fp->f_offset = uio->uio_offset;
fp->f_nextoff = uio->uio_offset;
VOP_UNLOCK(vp, 0, p);
return (error);
}
/*
* File table vnode write routine.
*/
static int
vn_write(fp, uio, cred, flags, p)
struct file *fp;
struct uio *uio;
struct ucred *cred;
struct proc *p;
int flags;
{
struct vnode *vp;
struct mount *mp;
int error, ioflag;
KASSERT(uio->uio_procp == p, ("uio_procp %p is not p %p",
uio->uio_procp, p));
vp = (struct vnode *)fp->f_data;
if (vp->v_type == VREG)
bwillwrite();
vp = (struct vnode *)fp->f_data; /* XXX needed? */
ioflag = IO_UNIT;
if (vp->v_type == VREG && (fp->f_flag & O_APPEND))
ioflag |= IO_APPEND;
if (fp->f_flag & FNONBLOCK)
ioflag |= IO_NDELAY;
if ((fp->f_flag & O_FSYNC) ||
(vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
ioflag |= IO_SYNC;
mp = NULL;
if (vp->v_type != VCHR && vp->v_type != VBLK &&
(error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) != 0)
return (error);
VOP_LEASE(vp, p, cred, LEASE_WRITE);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
if ((flags & FOF_OFFSET) == 0)
uio->uio_offset = fp->f_offset;
ioflag |= sequential_heuristic(uio, fp);
error = VOP_WRITE(vp, uio, ioflag, cred);
if ((flags & FOF_OFFSET) == 0)
fp->f_offset = uio->uio_offset;
fp->f_nextoff = uio->uio_offset;
VOP_UNLOCK(vp, 0, p);
vn_finished_write(mp);
return (error);
}
/*
* File table vnode stat routine.
*/
static int
vn_statfile(fp, sb, p)
struct file *fp;
struct stat *sb;
struct proc *p;
{
struct vnode *vp = (struct vnode *)fp->f_data;
return vn_stat(vp, sb, p);
}
int
vn_stat(vp, sb, p)
struct vnode *vp;
register struct stat *sb;
struct proc *p;
{
struct vattr vattr;
register struct vattr *vap;
int error;
u_short mode;
vap = &vattr;
error = VOP_GETATTR(vp, vap, p->p_ucred, p);
if (error)
return (error);
/*
* Zero the spare stat fields
*/
sb->st_lspare = 0;
sb->st_qspare[0] = 0;
sb->st_qspare[1] = 0;
/*
* Copy from vattr table
*/
if (vap->va_fsid != VNOVAL)
sb->st_dev = vap->va_fsid;
else
sb->st_dev = vp->v_mount->mnt_stat.f_fsid.val[0];
sb->st_ino = vap->va_fileid;
mode = vap->va_mode;
switch (vap->va_type) {
case VREG:
mode |= S_IFREG;
break;
case VDIR:
mode |= S_IFDIR;
break;
case VBLK:
mode |= S_IFBLK;
break;
case VCHR:
mode |= S_IFCHR;
break;
case VLNK:
mode |= S_IFLNK;
/* This is a cosmetic change, symlinks do not have a mode. */
if (vp->v_mount->mnt_flag & MNT_NOSYMFOLLOW)
sb->st_mode &= ~ACCESSPERMS; /* 0000 */
else
sb->st_mode |= ACCESSPERMS; /* 0777 */
break;
case VSOCK:
mode |= S_IFSOCK;
break;
case VFIFO:
mode |= S_IFIFO;
break;
default:
return (EBADF);
};
sb->st_mode = mode;
sb->st_nlink = vap->va_nlink;
sb->st_uid = vap->va_uid;
sb->st_gid = vap->va_gid;
sb->st_rdev = vap->va_rdev;
sb->st_size = vap->va_size;
sb->st_atimespec = vap->va_atime;
sb->st_mtimespec = vap->va_mtime;
sb->st_ctimespec = vap->va_ctime;
/*
* According to www.opengroup.org, the meaning of st_blksize is
* "a filesystem-specific preferred I/O block size for this
* object. In some filesystem types, this may vary from file
* to file"
* Default to zero to catch bogus uses of this field.
*/
if (vap->va_type == VREG) {
sb->st_blksize = vap->va_blocksize;
} else if (vn_isdisk(vp, NULL)) {
sb->st_blksize = vp->v_rdev->si_bsize_best;
if (sb->st_blksize < vp->v_rdev->si_bsize_phys)
sb->st_blksize = vp->v_rdev->si_bsize_phys;
if (sb->st_blksize < BLKDEV_IOSIZE)
sb->st_blksize = BLKDEV_IOSIZE;
} else {
sb->st_blksize = 0;
}
sb->st_flags = vap->va_flags;
if (suser_xxx(p->p_ucred, 0, 0))
sb->st_gen = 0;
else
sb->st_gen = vap->va_gen;
#if (S_BLKSIZE == 512)
/* Optimize this case */
sb->st_blocks = vap->va_bytes >> 9;
#else
sb->st_blocks = vap->va_bytes / S_BLKSIZE;
#endif
return (0);
}
/*
* File table vnode ioctl routine.
*/
static int
vn_ioctl(fp, com, data, p)
struct file *fp;
u_long com;
caddr_t data;
struct proc *p;
{
register struct vnode *vp = ((struct vnode *)fp->f_data);
struct vattr vattr;
int error;
switch (vp->v_type) {
case VREG:
case VDIR:
if (com == FIONREAD) {
error = VOP_GETATTR(vp, &vattr, p->p_ucred, p);
if (error)
return (error);
*(int *)data = vattr.va_size - fp->f_offset;
return (0);
}
if (com == FIONBIO || com == FIOASYNC) /* XXX */
return (0); /* XXX */
/* fall into ... */
default:
#if 0
return (ENOTTY);
#endif
case VFIFO:
case VCHR:
case VBLK:
if (com == FIODTYPE) {
if (vp->v_type != VCHR && vp->v_type != VBLK)
return (ENOTTY);
*(int *)data = devsw(vp->v_rdev)->d_flags & D_TYPEMASK;
return (0);
}
error = VOP_IOCTL(vp, com, data, fp->f_flag, p->p_ucred, p);
if (error == 0 && com == TIOCSCTTY) {
/* Do nothing if reassigning same control tty */
if (p->p_session->s_ttyvp == vp)
return (0);
/* Get rid of reference to old control tty */
if (p->p_session->s_ttyvp)
vrele(p->p_session->s_ttyvp);
p->p_session->s_ttyvp = vp;
VREF(vp);
}
return (error);
}
}
/*
* File table vnode poll routine.
*/
static int
vn_poll(fp, events, cred, p)
struct file *fp;
int events;
struct ucred *cred;
struct proc *p;
{
return (VOP_POLL(((struct vnode *)fp->f_data), events, cred, p));
}
/*
* Check that the vnode is still valid, and if so
* acquire requested lock.
*/
int
#ifndef DEBUG_LOCKS
vn_lock(vp, flags, p)
#else
debug_vn_lock(vp, flags, p, filename, line)
#endif
struct vnode *vp;
int flags;
struct proc *p;
#ifdef DEBUG_LOCKS
const char *filename;
int line;
#endif
{
int error;
do {
if ((flags & LK_INTERLOCK) == 0)
simple_lock(&vp->v_interlock);
if (vp->v_flag & VXLOCK) {
vp->v_flag |= VXWANT;
simple_unlock(&vp->v_interlock);
tsleep((caddr_t)vp, PINOD, "vn_lock", 0);
error = ENOENT;
} else {
#ifdef DEBUG_LOCKS
vp->filename = filename;
vp->line = line;
#endif
error = VOP_LOCK(vp,
flags | LK_NOPAUSE | LK_INTERLOCK, p);
if (error == 0)
return (error);
}
flags &= ~LK_INTERLOCK;
} while (flags & LK_RETRY);
return (error);
}
/*
* File table vnode close routine.
*/
static int
vn_closefile(fp, p)
struct file *fp;
struct proc *p;
{
fp->f_ops = &badfileops;
return (vn_close(((struct vnode *)fp->f_data), fp->f_flag,
fp->f_cred, p));
}
/*
* Preparing to start a filesystem write operation. If the operation is
* permitted, then we bump the count of operations in progress and
* proceed. If a suspend request is in progress, we wait until the
* suspension is over, and then proceed.
*/
int
vn_start_write(vp, mpp, flags)
struct vnode *vp;
struct mount **mpp;
int flags;
{
struct mount *mp;
int error;
/*
* If a vnode is provided, get and return the mount point that
* to which it will write.
*/
if (vp != NULL) {
if ((error = VOP_GETWRITEMOUNT(vp, mpp)) != 0) {
*mpp = NULL;
if (error != EOPNOTSUPP)
return (error);
return (0);
}
}
if ((mp = *mpp) == NULL)
return (0);
/*
* Check on status of suspension.
*/
while ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
if (flags & V_NOWAIT)
return (EWOULDBLOCK);
error = tsleep(&mp->mnt_flag, (PUSER - 1) | (flags & PCATCH),
"suspfs", 0);
if (error)
return (error);
}
if (flags & V_XSLEEP)
return (0);
mp->mnt_writeopcount++;
return (0);
}
/*
* Secondary suspension. Used by operations such as vop_inactive
* routines that are needed by the higher level functions. These
* are allowed to proceed until all the higher level functions have
* completed (indicated by mnt_writeopcount dropping to zero). At that
* time, these operations are halted until the suspension is over.
*/
int
vn_write_suspend_wait(vp, mp, flags)
struct vnode *vp;
struct mount *mp;
int flags;
{
int error;
if (vp != NULL) {
if ((error = VOP_GETWRITEMOUNT(vp, &mp)) != 0) {
if (error != EOPNOTSUPP)
return (error);
return (0);
}
}
/*
* If we are not suspended or have not yet reached suspended
* mode, then let the operation proceed.
*/
if (mp == NULL || (mp->mnt_kern_flag & MNTK_SUSPENDED) == 0)
return (0);
if (flags & V_NOWAIT)
return (EWOULDBLOCK);
/*
* Wait for the suspension to finish.
*/
return (tsleep(&mp->mnt_flag, (PUSER - 1) | (flags & PCATCH),
"suspfs", 0));
}
/*
* Filesystem write operation has completed. If we are suspending and this
* operation is the last one, notify the suspender that the suspension is
* now in effect.
*/
void
vn_finished_write(mp)
struct mount *mp;
{
if (mp == NULL)
return;
mp->mnt_writeopcount--;
if (mp->mnt_writeopcount < 0)
panic("vn_finished_write: neg cnt");
if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 &&
mp->mnt_writeopcount <= 0)
wakeup(&mp->mnt_writeopcount);
}
/*
* Request a filesystem to suspend write operations.
*/
void
vfs_write_suspend(mp)
struct mount *mp;
{
struct proc *p = curproc;
if (mp->mnt_kern_flag & MNTK_SUSPEND)
return;
mp->mnt_kern_flag |= MNTK_SUSPEND;
if (mp->mnt_writeopcount > 0)
(void) tsleep(&mp->mnt_writeopcount, PUSER - 1, "suspwt", 0);
VFS_SYNC(mp, MNT_WAIT, p->p_ucred, p);
mp->mnt_kern_flag |= MNTK_SUSPENDED;
}
/*
* Request a filesystem to resume write operations.
*/
void
vfs_write_resume(mp)
struct mount *mp;
{
if ((mp->mnt_kern_flag & MNTK_SUSPEND) == 0)
return;
mp->mnt_kern_flag &= ~(MNTK_SUSPEND | MNTK_SUSPENDED);
wakeup(&mp->mnt_writeopcount);
wakeup(&mp->mnt_flag);
}
static int
filt_vnattach(struct knote *kn)
{
struct vnode *vp;
if (kn->kn_fp->f_type != DTYPE_VNODE &&
kn->kn_fp->f_type != DTYPE_FIFO)
return (EBADF);
vp = (struct vnode *)kn->kn_fp->f_data;
/*
* XXX
* this is a hack simply to cause the filter attach to fail
* for non-ufs filesystems, until the support for them is done.
*/
if ((vp)->v_tag != VT_UFS)
return (EOPNOTSUPP);
simple_lock(&vp->v_pollinfo.vpi_lock);
SLIST_INSERT_HEAD(&vp->v_pollinfo.vpi_selinfo.si_note, kn, kn_selnext);
simple_unlock(&vp->v_pollinfo.vpi_lock);
return (0);
}
static void
filt_vndetach(struct knote *kn)
{
struct vnode *vp = (struct vnode *)kn->kn_fp->f_data;
simple_lock(&vp->v_pollinfo.vpi_lock);
SLIST_REMOVE(&vp->v_pollinfo.vpi_selinfo.si_note,
kn, knote, kn_selnext);
simple_unlock(&vp->v_pollinfo.vpi_lock);
}
static int
filt_vnode(struct knote *kn, long hint)
{
if (kn->kn_sfflags & hint)
kn->kn_fflags |= hint;
return (kn->kn_fflags != 0);
}
static int
filt_nullattach(struct knote *kn)
{
return (ENXIO);
}
/*ARGSUSED*/
static int
filt_vnread(struct knote *kn, long hint)
{
struct vnode *vp = (struct vnode *)kn->kn_fp->f_data;
struct inode *ip = VTOI(vp);
kn->kn_data = ip->i_size - kn->kn_fp->f_offset;
return (kn->kn_data != 0);
}
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