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freebsd/sys/kern/vfs_vnops.c
Konstantin Belousov 9bec6325ad When opening or closing fifo, ensure that the vnode is locked 
exclusively.  Filesystems are assumed to disable shared locking for
the fifo vnode locks, but some do not.

Reported and tested by:	olgeni
Discussed with:	avg
Sponsored by:   The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (glebius)
2013-09-13 06:52:23 +00:00

2086 lines
52 KiB
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Raw Blame History

/*-
* 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.
*
* Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
* Copyright (c) 2013 The FreeBSD Foundation
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
*
* 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.
* 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
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/disk.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/kdb.h>
#include <sys/stat.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/filio.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/ttycom.h>
#include <sys/conf.h>
#include <sys/syslog.h>
#include <sys/unistd.h>
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
static fo_rdwr_t vn_read;
static fo_rdwr_t vn_write;
static fo_rdwr_t vn_io_fault;
static fo_truncate_t vn_truncate;
static fo_ioctl_t vn_ioctl;
static fo_poll_t vn_poll;
static fo_kqfilter_t vn_kqfilter;
static fo_stat_t vn_statfile;
static fo_close_t vn_closefile;
struct fileops vnops = {
.fo_read = vn_io_fault,
.fo_write = vn_io_fault,
.fo_truncate = vn_truncate,
.fo_ioctl = vn_ioctl,
.fo_poll = vn_poll,
.fo_kqfilter = vn_kqfilter,
.fo_stat = vn_statfile,
.fo_close = vn_closefile,
.fo_chmod = vn_chmod,
.fo_chown = vn_chown,
.fo_sendfile = vn_sendfile,
.fo_seek = vn_seek,
.fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
};
int
vn_open(ndp, flagp, cmode, fp)
struct nameidata *ndp;
int *flagp, cmode;
struct file *fp;
{
struct thread *td = ndp->ni_cnd.cn_thread;
return (vn_open_cred(ndp, flagp, cmode, 0, td->td_ucred, fp));
}
/*
* Common code for vnode open operations via a name lookup.
* Lookup the vnode and invoke VOP_CREATE if needed.
* 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_cred(struct nameidata *ndp, int *flagp, int cmode, u_int vn_open_flags,
struct ucred *cred, struct file *fp)
{
struct vnode *vp;
struct mount *mp;
struct thread *td = ndp->ni_cnd.cn_thread;
struct vattr vat;
struct vattr *vap = &vat;
int fmode, error;
restart:
fmode = *flagp;
if (fmode & O_CREAT) {
ndp->ni_cnd.cn_nameiop = CREATE;
ndp->ni_cnd.cn_flags = ISOPEN | LOCKPARENT | LOCKLEAF;
if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
ndp->ni_cnd.cn_flags |= FOLLOW;
if (!(vn_open_flags & VN_OPEN_NOAUDIT))
ndp->ni_cnd.cn_flags |= AUDITVNODE1;
if (vn_open_flags & VN_OPEN_NOCAPCHECK)
ndp->ni_cnd.cn_flags |= NOCAPCHECK;
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;
}
#ifdef MAC
error = mac_vnode_check_create(cred, ndp->ni_dvp,
&ndp->ni_cnd, vap);
if (error == 0)
#endif
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);
}
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 = ISOPEN |
((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
if (!(fmode & FWRITE))
ndp->ni_cnd.cn_flags |= LOCKSHARED;
if (!(vn_open_flags & VN_OPEN_NOAUDIT))
ndp->ni_cnd.cn_flags |= AUDITVNODE1;
if (vn_open_flags & VN_OPEN_NOCAPCHECK)
ndp->ni_cnd.cn_flags |= NOCAPCHECK;
if ((error = namei(ndp)) != 0)
return (error);
vp = ndp->ni_vp;
}
error = vn_open_vnode(vp, fmode, cred, td, fp);
if (error)
goto bad;
*flagp = fmode;
return (0);
bad:
NDFREE(ndp, NDF_ONLY_PNBUF);
vput(vp);
*flagp = fmode;
ndp->ni_vp = NULL;
return (error);
}
/*
* Common code for vnode open operations once a vnode is located.
* Check permissions, and call the VOP_OPEN routine.
*/
int
vn_open_vnode(struct vnode *vp, int fmode, struct ucred *cred,
struct thread *td, struct file *fp)
{
struct mount *mp;
accmode_t accmode;
struct flock lf;
int error, have_flock, lock_flags, type;
if (vp->v_type == VLNK)
return (EMLINK);
if (vp->v_type == VSOCK)
return (EOPNOTSUPP);
if (vp->v_type != VDIR && fmode & O_DIRECTORY)
return (ENOTDIR);
accmode = 0;
if (fmode & (FWRITE | O_TRUNC)) {
if (vp->v_type == VDIR)
return (EISDIR);
accmode |= VWRITE;
}
if (fmode & FREAD)
accmode |= VREAD;
if (fmode & FEXEC)
accmode |= VEXEC;
if ((fmode & O_APPEND) && (fmode & FWRITE))
accmode |= VAPPEND;
#ifdef MAC
error = mac_vnode_check_open(cred, vp, accmode);
if (error)
return (error);
#endif
if ((fmode & O_CREAT) == 0) {
if (accmode & VWRITE) {
error = vn_writechk(vp);
if (error)
return (error);
}
if (accmode) {
error = VOP_ACCESS(vp, accmode, cred, td);
if (error)
return (error);
}
}
if (vp->v_type == VFIFO && VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
vn_lock(vp, LK_UPGRADE | LK_RETRY);
if ((error = VOP_OPEN(vp, fmode, cred, td, fp)) != 0)
return (error);
if (fmode & (O_EXLOCK | O_SHLOCK)) {
KASSERT(fp != NULL, ("open with flock requires fp"));
lock_flags = VOP_ISLOCKED(vp);
VOP_UNLOCK(vp, 0);
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
if (fmode & O_EXLOCK)
lf.l_type = F_WRLCK;
else
lf.l_type = F_RDLCK;
type = F_FLOCK;
if ((fmode & FNONBLOCK) == 0)
type |= F_WAIT;
error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, type);
have_flock = (error == 0);
vn_lock(vp, lock_flags | LK_RETRY);
if (error == 0 && vp->v_iflag & VI_DOOMED)
error = ENOENT;
/*
* Another thread might have used this vnode as an
* executable while the vnode lock was dropped.
* Ensure the vnode is still able to be opened for
* writing after the lock has been obtained.
*/
if (error == 0 && accmode & VWRITE)
error = vn_writechk(vp);
if (error) {
VOP_UNLOCK(vp, 0);
if (have_flock) {
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
lf.l_type = F_UNLCK;
(void) VOP_ADVLOCK(vp, fp, F_UNLCK, &lf,
F_FLOCK);
}
vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, lock_flags | LK_RETRY);
(void)VOP_CLOSE(vp, fmode, cred, td);
vn_finished_write(mp);
return (error);
}
fp->f_flag |= FHASLOCK;
}
if (fmode & FWRITE) {
VOP_ADD_WRITECOUNT(vp, 1);
CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
__func__, vp, vp->v_writecount);
}
ASSERT_VOP_LOCKED(vp, "vn_open_vnode");
return (0);
}
/*
* Check for write permissions on the specified vnode.
* Prototype text segments cannot be written.
*/
int
vn_writechk(vp)
register struct vnode *vp;
{
ASSERT_VOP_LOCKED(vp, "vn_writechk");
/*
* If there's shared text associated with
* the vnode, try to free it up once. If
* we fail, we can't allow writing.
*/
if (VOP_IS_TEXT(vp))
return (ETXTBSY);
return (0);
}
/*
* Vnode close call
*/
int
vn_close(vp, flags, file_cred, td)
register struct vnode *vp;
int flags;
struct ucred *file_cred;
struct thread *td;
{
struct mount *mp;
int error, lock_flags;
if (vp->v_type != VFIFO && !(flags & FWRITE) && vp->v_mount != NULL &&
vp->v_mount->mnt_kern_flag & MNTK_EXTENDED_SHARED)
lock_flags = LK_SHARED;
else
lock_flags = LK_EXCLUSIVE;
vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, lock_flags | LK_RETRY);
if (flags & FWRITE) {
VNASSERT(vp->v_writecount > 0, vp,
("vn_close: negative writecount"));
VOP_ADD_WRITECOUNT(vp, -1);
CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
__func__, vp, vp->v_writecount);
}
error = VOP_CLOSE(vp, flags, file_cred, td);
vput(vp);
vn_finished_write(mp);
return (error);
}
/*
* Heuristic to detect sequential operation.
*/
static int
sequential_heuristic(struct uio *uio, struct file *fp)
{
if (atomic_load_acq_int(&(fp->f_flag)) & FRDAHEAD)
return (fp->f_seqcount << IO_SEQSHIFT);
/*
* Offset 0 is handled specially. open() sets f_seqcount to 1 so
* that the first I/O is normally considered to be slightly
* sequential. Seeking to offset 0 doesn't change sequentiality
* unless previous seeks have reduced f_seqcount to 0, in which
* case offset 0 is not special.
*/
if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
uio->uio_offset == fp->f_nextoff) {
/*
* f_seqcount is in units of fixed-size blocks so that it
* depends mainly on the amount of sequential I/O and not
* much on the number of sequential I/O's. The fixed size
* of 16384 is hard-coded here since it is (not quite) just
* a magic size that works well here. This size is more
* closely related to the best I/O size for real disks than
* to any block size used by software.
*/
fp->f_seqcount += howmany(uio->uio_resid, 16384);
if (fp->f_seqcount > IO_SEQMAX)
fp->f_seqcount = IO_SEQMAX;
return (fp->f_seqcount << IO_SEQSHIFT);
}
/* Not sequential. Quickly draw-down sequentiality. */
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(enum uio_rw rw, struct vnode *vp, void *base, int len, off_t offset,
enum uio_seg segflg, int ioflg, struct ucred *active_cred,
struct ucred *file_cred, ssize_t *aresid, struct thread *td)
{
struct uio auio;
struct iovec aiov;
struct mount *mp;
struct ucred *cred;
void *rl_cookie;
int error, lock_flags;
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_td = td;
error = 0;
if ((ioflg & IO_NODELOCKED) == 0) {
if (rw == UIO_READ) {
rl_cookie = vn_rangelock_rlock(vp, offset,
offset + len);
} else {
rl_cookie = vn_rangelock_wlock(vp, offset,
offset + len);
}
mp = NULL;
if (rw == UIO_WRITE) {
if (vp->v_type != VCHR &&
(error = vn_start_write(vp, &mp, V_WAIT | PCATCH))
!= 0)
goto out;
if (MNT_SHARED_WRITES(mp) ||
((mp == NULL) && MNT_SHARED_WRITES(vp->v_mount)))
lock_flags = LK_SHARED;
else
lock_flags = LK_EXCLUSIVE;
} else
lock_flags = LK_SHARED;
vn_lock(vp, lock_flags | LK_RETRY);
} else
rl_cookie = NULL;
ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
#ifdef MAC
if ((ioflg & IO_NOMACCHECK) == 0) {
if (rw == UIO_READ)
error = mac_vnode_check_read(active_cred, file_cred,
vp);
else
error = mac_vnode_check_write(active_cred, file_cred,
vp);
}
#endif
if (error == 0) {
if (file_cred != NULL)
cred = file_cred;
else
cred = active_cred;
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) {
VOP_UNLOCK(vp, 0);
if (mp != NULL)
vn_finished_write(mp);
}
out:
if (rl_cookie != NULL)
vn_rangelock_unlock(vp, rl_cookie);
return (error);
}
/*
* Package up an I/O request on a vnode into a uio and do it. The I/O
* request is split up into smaller chunks and we try to avoid saturating
* the buffer cache while potentially holding a vnode locked, so we
* check bwillwrite() before calling vn_rdwr(). We also call kern_yield()
* to give other processes a chance to lock the vnode (either other processes
* core'ing the same binary, or unrelated processes scanning the directory).
*/
int
vn_rdwr_inchunks(rw, vp, base, len, offset, segflg, ioflg, active_cred,
file_cred, aresid, td)
enum uio_rw rw;
struct vnode *vp;
void *base;
size_t len;
off_t offset;
enum uio_seg segflg;
int ioflg;
struct ucred *active_cred;
struct ucred *file_cred;
size_t *aresid;
struct thread *td;
{
int error = 0;
ssize_t iaresid;
do {
int chunk;
/*
* Force `offset' to a multiple of MAXBSIZE except possibly
* for the first chunk, so that filesystems only need to
* write full blocks except possibly for the first and last
* chunks.
*/
chunk = MAXBSIZE - (uoff_t)offset % MAXBSIZE;
if (chunk > len)
chunk = len;
if (rw != UIO_READ && vp->v_type == VREG)
bwillwrite();
iaresid = 0;
error = vn_rdwr(rw, vp, base, chunk, offset, segflg,
ioflg, active_cred, file_cred, &iaresid, td);
len -= chunk; /* aresid calc already includes length */
if (error)
break;
offset += chunk;
base = (char *)base + chunk;
kern_yield(PRI_USER);
} while (len);
if (aresid)
*aresid = len + iaresid;
return (error);
}
off_t
foffset_lock(struct file *fp, int flags)
{
struct mtx *mtxp;
off_t res;
KASSERT((flags & FOF_OFFSET) == 0, ("FOF_OFFSET passed"));
#if OFF_MAX <= LONG_MAX
/*
* Caller only wants the current f_offset value. Assume that
* the long and shorter integer types reads are atomic.
*/
if ((flags & FOF_NOLOCK) != 0)
return (fp->f_offset);
#endif
/*
* According to McKusick the vn lock was protecting f_offset here.
* It is now protected by the FOFFSET_LOCKED flag.
*/
mtxp = mtx_pool_find(mtxpool_sleep, fp);
mtx_lock(mtxp);
if ((flags & FOF_NOLOCK) == 0) {
while (fp->f_vnread_flags & FOFFSET_LOCKED) {
fp->f_vnread_flags |= FOFFSET_LOCK_WAITING;
msleep(&fp->f_vnread_flags, mtxp, PUSER -1,
"vofflock", 0);
}
fp->f_vnread_flags |= FOFFSET_LOCKED;
}
res = fp->f_offset;
mtx_unlock(mtxp);
return (res);
}
void
foffset_unlock(struct file *fp, off_t val, int flags)
{
struct mtx *mtxp;
KASSERT((flags & FOF_OFFSET) == 0, ("FOF_OFFSET passed"));
#if OFF_MAX <= LONG_MAX
if ((flags & FOF_NOLOCK) != 0) {
if ((flags & FOF_NOUPDATE) == 0)
fp->f_offset = val;
if ((flags & FOF_NEXTOFF) != 0)
fp->f_nextoff = val;
return;
}
#endif
mtxp = mtx_pool_find(mtxpool_sleep, fp);
mtx_lock(mtxp);
if ((flags & FOF_NOUPDATE) == 0)
fp->f_offset = val;
if ((flags & FOF_NEXTOFF) != 0)
fp->f_nextoff = val;
if ((flags & FOF_NOLOCK) == 0) {
KASSERT((fp->f_vnread_flags & FOFFSET_LOCKED) != 0,
("Lost FOFFSET_LOCKED"));
if (fp->f_vnread_flags & FOFFSET_LOCK_WAITING)
wakeup(&fp->f_vnread_flags);
fp->f_vnread_flags = 0;
}
mtx_unlock(mtxp);
}
void
foffset_lock_uio(struct file *fp, struct uio *uio, int flags)
{
if ((flags & FOF_OFFSET) == 0)
uio->uio_offset = foffset_lock(fp, flags);
}
void
foffset_unlock_uio(struct file *fp, struct uio *uio, int flags)
{
if ((flags & FOF_OFFSET) == 0)
foffset_unlock(fp, uio->uio_offset, flags);
}
static int
get_advice(struct file *fp, struct uio *uio)
{
struct mtx *mtxp;
int ret;
ret = POSIX_FADV_NORMAL;
if (fp->f_advice == NULL)
return (ret);
mtxp = mtx_pool_find(mtxpool_sleep, fp);
mtx_lock(mtxp);
if (uio->uio_offset >= fp->f_advice->fa_start &&
uio->uio_offset + uio->uio_resid <= fp->f_advice->fa_end)
ret = fp->f_advice->fa_advice;
mtx_unlock(mtxp);
return (ret);
}
/*
* File table vnode read routine.
*/
static int
vn_read(fp, uio, active_cred, flags, td)
struct file *fp;
struct uio *uio;
struct ucred *active_cred;
int flags;
struct thread *td;
{
struct vnode *vp;
struct mtx *mtxp;
int error, ioflag;
int advice;
off_t offset, start, end;
KASSERT(uio->uio_td == td, ("uio_td %p is not td %p",
uio->uio_td, td));
KASSERT(flags & FOF_OFFSET, ("No FOF_OFFSET"));
vp = fp->f_vnode;
ioflag = 0;
if (fp->f_flag & FNONBLOCK)
ioflag |= IO_NDELAY;
if (fp->f_flag & O_DIRECT)
ioflag |= IO_DIRECT;
advice = get_advice(fp, uio);
vn_lock(vp, LK_SHARED | LK_RETRY);
switch (advice) {
case POSIX_FADV_NORMAL:
case POSIX_FADV_SEQUENTIAL:
case POSIX_FADV_NOREUSE:
ioflag |= sequential_heuristic(uio, fp);
break;
case POSIX_FADV_RANDOM:
/* Disable read-ahead for random I/O. */
break;
}
offset = uio->uio_offset;
#ifdef MAC
error = mac_vnode_check_read(active_cred, fp->f_cred, vp);
if (error == 0)
#endif
error = VOP_READ(vp, uio, ioflag, fp->f_cred);
fp->f_nextoff = uio->uio_offset;
VOP_UNLOCK(vp, 0);
if (error == 0 && advice == POSIX_FADV_NOREUSE &&
offset != uio->uio_offset) {
/*
* Use POSIX_FADV_DONTNEED to flush clean pages and
* buffers for the backing file after a
* POSIX_FADV_NOREUSE read(2). To optimize the common
* case of using POSIX_FADV_NOREUSE with sequential
* access, track the previous implicit DONTNEED
* request and grow this request to include the
* current read(2) in addition to the previous
* DONTNEED. With purely sequential access this will
* cause the DONTNEED requests to continously grow to
* cover all of the previously read regions of the
* file. This allows filesystem blocks that are
* accessed by multiple calls to read(2) to be flushed
* once the last read(2) finishes.
*/
start = offset;
end = uio->uio_offset - 1;
mtxp = mtx_pool_find(mtxpool_sleep, fp);
mtx_lock(mtxp);
if (fp->f_advice != NULL &&
fp->f_advice->fa_advice == POSIX_FADV_NOREUSE) {
if (start != 0 && fp->f_advice->fa_prevend + 1 == start)
start = fp->f_advice->fa_prevstart;
else if (fp->f_advice->fa_prevstart != 0 &&
fp->f_advice->fa_prevstart == end + 1)
end = fp->f_advice->fa_prevend;
fp->f_advice->fa_prevstart = start;
fp->f_advice->fa_prevend = end;
}
mtx_unlock(mtxp);
error = VOP_ADVISE(vp, start, end, POSIX_FADV_DONTNEED);
}
return (error);
}
/*
* File table vnode write routine.
*/
static int
vn_write(fp, uio, active_cred, flags, td)
struct file *fp;
struct uio *uio;
struct ucred *active_cred;
int flags;
struct thread *td;
{
struct vnode *vp;
struct mount *mp;
struct mtx *mtxp;
int error, ioflag, lock_flags;
int advice;
off_t offset, start, end;
KASSERT(uio->uio_td == td, ("uio_td %p is not td %p",
uio->uio_td, td));
KASSERT(flags & FOF_OFFSET, ("No FOF_OFFSET"));
vp = fp->f_vnode;
if (vp->v_type == VREG)
bwillwrite();
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_DIRECT)
ioflag |= IO_DIRECT;
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 &&
(error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) != 0)
goto unlock;
advice = get_advice(fp, uio);
if (MNT_SHARED_WRITES(mp) ||
(mp == NULL && MNT_SHARED_WRITES(vp->v_mount))) {
lock_flags = LK_SHARED;
} else {
lock_flags = LK_EXCLUSIVE;
}
vn_lock(vp, lock_flags | LK_RETRY);
switch (advice) {
case POSIX_FADV_NORMAL:
case POSIX_FADV_SEQUENTIAL:
case POSIX_FADV_NOREUSE:
ioflag |= sequential_heuristic(uio, fp);
break;
case POSIX_FADV_RANDOM:
/* XXX: Is this correct? */
break;
}
offset = uio->uio_offset;
#ifdef MAC
error = mac_vnode_check_write(active_cred, fp->f_cred, vp);
if (error == 0)
#endif
error = VOP_WRITE(vp, uio, ioflag, fp->f_cred);
fp->f_nextoff = uio->uio_offset;
VOP_UNLOCK(vp, 0);
if (vp->v_type != VCHR)
vn_finished_write(mp);
if (error == 0 && advice == POSIX_FADV_NOREUSE &&
offset != uio->uio_offset) {
/*
* Use POSIX_FADV_DONTNEED to flush clean pages and
* buffers for the backing file after a
* POSIX_FADV_NOREUSE write(2). To optimize the
* common case of using POSIX_FADV_NOREUSE with
* sequential access, track the previous implicit
* DONTNEED request and grow this request to include
* the current write(2) in addition to the previous
* DONTNEED. With purely sequential access this will
* cause the DONTNEED requests to continously grow to
* cover all of the previously written regions of the
* file.
*
* Note that the blocks just written are almost
* certainly still dirty, so this only works when
* VOP_ADVISE() calls from subsequent writes push out
* the data written by this write(2) once the backing
* buffers are clean. However, as compared to forcing
* IO_DIRECT, this gives much saner behavior. Write
* clustering is still allowed, and clean pages are
* merely moved to the cache page queue rather than
* outright thrown away. This means a subsequent
* read(2) can still avoid hitting the disk if the
* pages have not been reclaimed.
*
* This does make POSIX_FADV_NOREUSE largely useless
* with non-sequential access. However, sequential
* access is the more common use case and the flag is
* merely advisory.
*/
start = offset;
end = uio->uio_offset - 1;
mtxp = mtx_pool_find(mtxpool_sleep, fp);
mtx_lock(mtxp);
if (fp->f_advice != NULL &&
fp->f_advice->fa_advice == POSIX_FADV_NOREUSE) {
if (start != 0 && fp->f_advice->fa_prevend + 1 == start)
start = fp->f_advice->fa_prevstart;
else if (fp->f_advice->fa_prevstart != 0 &&
fp->f_advice->fa_prevstart == end + 1)
end = fp->f_advice->fa_prevend;
fp->f_advice->fa_prevstart = start;
fp->f_advice->fa_prevend = end;
}
mtx_unlock(mtxp);
error = VOP_ADVISE(vp, start, end, POSIX_FADV_DONTNEED);
}
unlock:
return (error);
}
static const int io_hold_cnt = 16;
static int vn_io_fault_enable = 1;
SYSCTL_INT(_debug, OID_AUTO, vn_io_fault_enable, CTLFLAG_RW,
&vn_io_fault_enable, 0, "Enable vn_io_fault lock avoidance");
static u_long vn_io_faults_cnt;
SYSCTL_ULONG(_debug, OID_AUTO, vn_io_faults, CTLFLAG_RD,
&vn_io_faults_cnt, 0, "Count of vn_io_fault lock avoidance triggers");
/*
* The vn_io_fault() is a wrapper around vn_read() and vn_write() to
* prevent the following deadlock:
*
* Assume that the thread A reads from the vnode vp1 into userspace
* buffer buf1 backed by the pages of vnode vp2. If a page in buf1 is
* currently not resident, then system ends up with the call chain
* vn_read() -> VOP_READ(vp1) -> uiomove() -> [Page Fault] ->
* vm_fault(buf1) -> vnode_pager_getpages(vp2) -> VOP_GETPAGES(vp2)
* which establishes lock order vp1->vn_lock, then vp2->vn_lock.
* If, at the same time, thread B reads from vnode vp2 into buffer buf2
* backed by the pages of vnode vp1, and some page in buf2 is not
* resident, we get a reversed order vp2->vn_lock, then vp1->vn_lock.
*
* To prevent the lock order reversal and deadlock, vn_io_fault() does
* not allow page faults to happen during VOP_READ() or VOP_WRITE().
* Instead, it first tries to do the whole range i/o with pagefaults
* disabled. If all pages in the i/o buffer are resident and mapped,
* VOP will succeed (ignoring the genuine filesystem errors).
* Otherwise, we get back EFAULT, and vn_io_fault() falls back to do
* i/o in chunks, with all pages in the chunk prefaulted and held
* using vm_fault_quick_hold_pages().
*
* Filesystems using this deadlock avoidance scheme should use the
* array of the held pages from uio, saved in the curthread->td_ma,
* instead of doing uiomove(). A helper function
* vn_io_fault_uiomove() converts uiomove request into
* uiomove_fromphys() over td_ma array.
*
* Since vnode locks do not cover the whole i/o anymore, rangelocks
* make the current i/o request atomic with respect to other i/os and
* truncations.
*/
static int
vn_io_fault(struct file *fp, struct uio *uio, struct ucred *active_cred,
int flags, struct thread *td)
{
vm_page_t ma[io_hold_cnt + 2];
struct uio *uio_clone, short_uio;
struct iovec short_iovec[1];
fo_rdwr_t *doio;
struct vnode *vp;
void *rl_cookie;
struct mount *mp;
vm_page_t *prev_td_ma;
int cnt, error, save, saveheld, prev_td_ma_cnt;
vm_offset_t addr, end;
vm_prot_t prot;
size_t len, resid;
ssize_t adv;
if (uio->uio_rw == UIO_READ)
doio = vn_read;
else
doio = vn_write;
vp = fp->f_vnode;
foffset_lock_uio(fp, uio, flags);
if (uio->uio_segflg != UIO_USERSPACE || vp->v_type != VREG ||
((mp = vp->v_mount) != NULL &&
(mp->mnt_kern_flag & MNTK_NO_IOPF) == 0) ||
!vn_io_fault_enable) {
error = doio(fp, uio, active_cred, flags | FOF_OFFSET, td);
goto out_last;
}
/*
* The UFS follows IO_UNIT directive and replays back both
* uio_offset and uio_resid if an error is encountered during the
* operation. But, since the iovec may be already advanced,
* uio is still in an inconsistent state.
*
* Cache a copy of the original uio, which is advanced to the redo
* point using UIO_NOCOPY below.
*/
uio_clone = cloneuio(uio);
resid = uio->uio_resid;
short_uio.uio_segflg = UIO_USERSPACE;
short_uio.uio_rw = uio->uio_rw;
short_uio.uio_td = uio->uio_td;
if (uio->uio_rw == UIO_READ) {
prot = VM_PROT_WRITE;
rl_cookie = vn_rangelock_rlock(vp, uio->uio_offset,
uio->uio_offset + uio->uio_resid);
} else {
prot = VM_PROT_READ;
if ((fp->f_flag & O_APPEND) != 0 || (flags & FOF_OFFSET) == 0)
/* For appenders, punt and lock the whole range. */
rl_cookie = vn_rangelock_wlock(vp, 0, OFF_MAX);
else
rl_cookie = vn_rangelock_wlock(vp, uio->uio_offset,
uio->uio_offset + uio->uio_resid);
}
save = vm_fault_disable_pagefaults();
error = doio(fp, uio, active_cred, flags | FOF_OFFSET, td);
if (error != EFAULT)
goto out;
atomic_add_long(&vn_io_faults_cnt, 1);
uio_clone->uio_segflg = UIO_NOCOPY;
uiomove(NULL, resid - uio->uio_resid, uio_clone);
uio_clone->uio_segflg = uio->uio_segflg;
saveheld = curthread_pflags_set(TDP_UIOHELD);
prev_td_ma = td->td_ma;
prev_td_ma_cnt = td->td_ma_cnt;
while (uio_clone->uio_resid != 0) {
len = uio_clone->uio_iov->iov_len;
if (len == 0) {
KASSERT(uio_clone->uio_iovcnt >= 1,
("iovcnt underflow"));
uio_clone->uio_iov++;
uio_clone->uio_iovcnt--;
continue;
}
addr = (vm_offset_t)uio_clone->uio_iov->iov_base;
end = round_page(addr + len);
cnt = howmany(end - trunc_page(addr), PAGE_SIZE);
/*
* A perfectly misaligned address and length could cause
* both the start and the end of the chunk to use partial
* page. +2 accounts for such a situation.
*/
if (cnt > io_hold_cnt + 2) {
len = io_hold_cnt * PAGE_SIZE;
KASSERT(howmany(round_page(addr + len) -
trunc_page(addr), PAGE_SIZE) <= io_hold_cnt + 2,
("cnt overflow"));
}
cnt = vm_fault_quick_hold_pages(&td->td_proc->p_vmspace->vm_map,
addr, len, prot, ma, io_hold_cnt + 2);
if (cnt == -1) {
error = EFAULT;
break;
}
short_uio.uio_iov = &short_iovec[0];
short_iovec[0].iov_base = (void *)addr;
short_uio.uio_iovcnt = 1;
short_uio.uio_resid = short_iovec[0].iov_len = len;
short_uio.uio_offset = uio_clone->uio_offset;
td->td_ma = ma;
td->td_ma_cnt = cnt;
error = doio(fp, &short_uio, active_cred, flags | FOF_OFFSET,
td);
vm_page_unhold_pages(ma, cnt);
adv = len - short_uio.uio_resid;
uio_clone->uio_iov->iov_base =
(char *)uio_clone->uio_iov->iov_base + adv;
uio_clone->uio_iov->iov_len -= adv;
uio_clone->uio_resid -= adv;
uio_clone->uio_offset += adv;
uio->uio_resid -= adv;
uio->uio_offset += adv;
if (error != 0 || adv == 0)
break;
}
td->td_ma = prev_td_ma;
td->td_ma_cnt = prev_td_ma_cnt;
curthread_pflags_restore(saveheld);
out:
vm_fault_enable_pagefaults(save);
vn_rangelock_unlock(vp, rl_cookie);
free(uio_clone, M_IOV);
out_last:
foffset_unlock_uio(fp, uio, flags);
return (error);
}
/*
* Helper function to perform the requested uiomove operation using
* the held pages for io->uio_iov[0].iov_base buffer instead of
* copyin/copyout. Access to the pages with uiomove_fromphys()
* instead of iov_base prevents page faults that could occur due to
* pmap_collect() invalidating the mapping created by
* vm_fault_quick_hold_pages(), or pageout daemon, page laundry or
* object cleanup revoking the write access from page mappings.
*
* Filesystems specified MNTK_NO_IOPF shall use vn_io_fault_uiomove()
* instead of plain uiomove().
*/
int
vn_io_fault_uiomove(char *data, int xfersize, struct uio *uio)
{
struct uio transp_uio;
struct iovec transp_iov[1];
struct thread *td;
size_t adv;
int error, pgadv;
td = curthread;
if ((td->td_pflags & TDP_UIOHELD) == 0 ||
uio->uio_segflg != UIO_USERSPACE)
return (uiomove(data, xfersize, uio));
KASSERT(uio->uio_iovcnt == 1, ("uio_iovcnt %d", uio->uio_iovcnt));
transp_iov[0].iov_base = data;
transp_uio.uio_iov = &transp_iov[0];
transp_uio.uio_iovcnt = 1;
if (xfersize > uio->uio_resid)
xfersize = uio->uio_resid;
transp_uio.uio_resid = transp_iov[0].iov_len = xfersize;
transp_uio.uio_offset = 0;
transp_uio.uio_segflg = UIO_SYSSPACE;
/*
* Since transp_iov points to data, and td_ma page array
* corresponds to original uio->uio_iov, we need to invert the
* direction of the i/o operation as passed to
* uiomove_fromphys().
*/
switch (uio->uio_rw) {
case UIO_WRITE:
transp_uio.uio_rw = UIO_READ;
break;
case UIO_READ:
transp_uio.uio_rw = UIO_WRITE;
break;
}
transp_uio.uio_td = uio->uio_td;
error = uiomove_fromphys(td->td_ma,
((vm_offset_t)uio->uio_iov->iov_base) & PAGE_MASK,
xfersize, &transp_uio);
adv = xfersize - transp_uio.uio_resid;
pgadv =
(((vm_offset_t)uio->uio_iov->iov_base + adv) >> PAGE_SHIFT) -
(((vm_offset_t)uio->uio_iov->iov_base) >> PAGE_SHIFT);
td->td_ma += pgadv;
KASSERT(td->td_ma_cnt >= pgadv, ("consumed pages %d %d", td->td_ma_cnt,
pgadv));
td->td_ma_cnt -= pgadv;
uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + adv;
uio->uio_iov->iov_len -= adv;
uio->uio_resid -= adv;
uio->uio_offset += adv;
return (error);
}
int
vn_io_fault_pgmove(vm_page_t ma[], vm_offset_t offset, int xfersize,
struct uio *uio)
{
struct thread *td;
vm_offset_t iov_base;
int cnt, pgadv;
td = curthread;
if ((td->td_pflags & TDP_UIOHELD) == 0 ||
uio->uio_segflg != UIO_USERSPACE)
return (uiomove_fromphys(ma, offset, xfersize, uio));
KASSERT(uio->uio_iovcnt == 1, ("uio_iovcnt %d", uio->uio_iovcnt));
cnt = xfersize > uio->uio_resid ? uio->uio_resid : xfersize;
iov_base = (vm_offset_t)uio->uio_iov->iov_base;
switch (uio->uio_rw) {
case UIO_WRITE:
pmap_copy_pages(td->td_ma, iov_base & PAGE_MASK, ma,
offset, cnt);
break;
case UIO_READ:
pmap_copy_pages(ma, offset, td->td_ma, iov_base & PAGE_MASK,
cnt);
break;
}
pgadv = ((iov_base + cnt) >> PAGE_SHIFT) - (iov_base >> PAGE_SHIFT);
td->td_ma += pgadv;
KASSERT(td->td_ma_cnt >= pgadv, ("consumed pages %d %d", td->td_ma_cnt,
pgadv));
td->td_ma_cnt -= pgadv;
uio->uio_iov->iov_base = (char *)(iov_base + cnt);
uio->uio_iov->iov_len -= cnt;
uio->uio_resid -= cnt;
uio->uio_offset += cnt;
return (0);
}
/*
* File table truncate routine.
*/
static int
vn_truncate(struct file *fp, off_t length, struct ucred *active_cred,
struct thread *td)
{
struct vattr vattr;
struct mount *mp;
struct vnode *vp;
void *rl_cookie;
int error;
vp = fp->f_vnode;
/*
* Lock the whole range for truncation. Otherwise split i/o
* might happen partly before and partly after the truncation.
*/
rl_cookie = vn_rangelock_wlock(vp, 0, OFF_MAX);
error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
if (error)
goto out1;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
if (vp->v_type == VDIR) {
error = EISDIR;
goto out;
}
#ifdef MAC
error = mac_vnode_check_write(active_cred, fp->f_cred, vp);
if (error)
goto out;
#endif
error = vn_writechk(vp);
if (error == 0) {
VATTR_NULL(&vattr);
vattr.va_size = length;
error = VOP_SETATTR(vp, &vattr, fp->f_cred);
}
out:
VOP_UNLOCK(vp, 0);
vn_finished_write(mp);
out1:
vn_rangelock_unlock(vp, rl_cookie);
return (error);
}
/*
* File table vnode stat routine.
*/
static int
vn_statfile(fp, sb, active_cred, td)
struct file *fp;
struct stat *sb;
struct ucred *active_cred;
struct thread *td;
{
struct vnode *vp = fp->f_vnode;
int error;
vn_lock(vp, LK_SHARED | LK_RETRY);
error = vn_stat(vp, sb, active_cred, fp->f_cred, td);
VOP_UNLOCK(vp, 0);
return (error);
}
/*
* Stat a vnode; implementation for the stat syscall
*/
int
vn_stat(vp, sb, active_cred, file_cred, td)
struct vnode *vp;
register struct stat *sb;
struct ucred *active_cred;
struct ucred *file_cred;
struct thread *td;
{
struct vattr vattr;
register struct vattr *vap;
int error;
u_short mode;
#ifdef MAC
error = mac_vnode_check_stat(active_cred, file_cred, vp);
if (error)
return (error);
#endif
vap = &vattr;
/*
* Initialize defaults for new and unusual fields, so that file
* systems which don't support these fields don't need to know
* about them.
*/
vap->va_birthtime.tv_sec = -1;
vap->va_birthtime.tv_nsec = 0;
vap->va_fsid = VNOVAL;
vap->va_rdev = NODEV;
error = VOP_GETATTR(vp, vap, active_cred);
if (error)
return (error);
/*
* Zero the spare stat fields
*/
bzero(sb, sizeof *sb);
/*
* 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;
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;
if (vap->va_size > OFF_MAX)
return (EOVERFLOW);
sb->st_size = vap->va_size;
sb->st_atim = vap->va_atime;
sb->st_mtim = vap->va_mtime;
sb->st_ctim = vap->va_ctime;
sb->st_birthtim = vap->va_birthtime;
/*
* 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"
* Use miminum/default of PAGE_SIZE (e.g. for VCHR).
*/
sb->st_blksize = max(PAGE_SIZE, vap->va_blocksize);
sb->st_flags = vap->va_flags;
if (priv_check(td, PRIV_VFS_GENERATION))
sb->st_gen = 0;
else
sb->st_gen = vap->va_gen;
sb->st_blocks = vap->va_bytes / S_BLKSIZE;
return (0);
}
/*
* File table vnode ioctl routine.
*/
static int
vn_ioctl(fp, com, data, active_cred, td)
struct file *fp;
u_long com;
void *data;
struct ucred *active_cred;
struct thread *td;
{
struct vattr vattr;
struct vnode *vp;
int error;
vp = fp->f_vnode;
switch (vp->v_type) {
case VDIR:
case VREG:
switch (com) {
case FIONREAD:
vn_lock(vp, LK_SHARED | LK_RETRY);
error = VOP_GETATTR(vp, &vattr, active_cred);
VOP_UNLOCK(vp, 0);
if (error == 0)
*(int *)data = vattr.va_size - fp->f_offset;
return (error);
case FIONBIO:
case FIOASYNC:
return (0);
default:
return (VOP_IOCTL(vp, com, data, fp->f_flag,
active_cred, td));
}
default:
return (ENOTTY);
}
}
/*
* File table vnode poll routine.
*/
static int
vn_poll(fp, events, active_cred, td)
struct file *fp;
int events;
struct ucred *active_cred;
struct thread *td;
{
struct vnode *vp;
int error;
vp = fp->f_vnode;
#ifdef MAC
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
error = mac_vnode_check_poll(active_cred, fp->f_cred, vp);
VOP_UNLOCK(vp, 0);
if (!error)
#endif
error = VOP_POLL(vp, events, fp->f_cred, td);
return (error);
}
/*
* Acquire the requested lock and then check for validity. LK_RETRY
* permits vn_lock to return doomed vnodes.
*/
int
_vn_lock(struct vnode *vp, int flags, char *file, int line)
{
int error;
VNASSERT((flags & LK_TYPE_MASK) != 0, vp,
("vn_lock called with no locktype."));
do {
#ifdef DEBUG_VFS_LOCKS
KASSERT(vp->v_holdcnt != 0,
("vn_lock %p: zero hold count", vp));
#endif
error = VOP_LOCK1(vp, flags, file, line);
flags &= ~LK_INTERLOCK; /* Interlock is always dropped. */
KASSERT((flags & LK_RETRY) == 0 || error == 0,
("LK_RETRY set with incompatible flags (0x%x) or an error occured (%d)",
flags, error));
/*
* Callers specify LK_RETRY if they wish to get dead vnodes.
* If RETRY is not set, we return ENOENT instead.
*/
if (error == 0 && vp->v_iflag & VI_DOOMED &&
(flags & LK_RETRY) == 0) {
VOP_UNLOCK(vp, 0);
error = ENOENT;
break;
}
} while (flags & LK_RETRY && error != 0);
return (error);
}
/*
* File table vnode close routine.
*/
static int
vn_closefile(fp, td)
struct file *fp;
struct thread *td;
{
struct vnode *vp;
struct flock lf;
int error;
vp = fp->f_vnode;
fp->f_ops = &badfileops;
if (fp->f_type == DTYPE_VNODE && fp->f_flag & FHASLOCK)
vref(vp);
error = vn_close(vp, fp->f_flag, fp->f_cred, td);
if (fp->f_type == DTYPE_VNODE && fp->f_flag & FHASLOCK) {
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
lf.l_type = F_UNLCK;
(void) VOP_ADVLOCK(vp, fp, F_UNLCK, &lf, F_FLOCK);
vrele(vp);
}
return (error);
}
/*
* 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.
*/
static int
vn_start_write_locked(struct mount *mp, int flags)
{
int error;
mtx_assert(MNT_MTX(mp), MA_OWNED);
error = 0;
/*
* Check on status of suspension.
*/
if ((curthread->td_pflags & TDP_IGNSUSP) == 0 ||
mp->mnt_susp_owner != curthread) {
while ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
if (flags & V_NOWAIT) {
error = EWOULDBLOCK;
goto unlock;
}
error = msleep(&mp->mnt_flag, MNT_MTX(mp),
(PUSER - 1) | (flags & PCATCH), "suspfs", 0);
if (error)
goto unlock;
}
}
if (flags & V_XSLEEP)
goto unlock;
mp->mnt_writeopcount++;
unlock:
if (error != 0 || (flags & V_XSLEEP) != 0)
MNT_REL(mp);
MNT_IUNLOCK(mp);
return (error);
}
int
vn_start_write(vp, mpp, flags)
struct vnode *vp;
struct mount **mpp;
int flags;
{
struct mount *mp;
int error;
error = 0;
/*
* 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);
/*
* VOP_GETWRITEMOUNT() returns with the mp refcount held through
* a vfs_ref().
* As long as a vnode is not provided we need to acquire a
* refcount for the provided mountpoint too, in order to
* emulate a vfs_ref().
*/
MNT_ILOCK(mp);
if (vp == NULL)
MNT_REF(mp);
return (vn_start_write_locked(mp, flags));
}
/*
* 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_start_secondary_write(vp, mpp, flags)
struct vnode *vp;
struct mount **mpp;
int flags;
{
struct mount *mp;
int error;
retry:
if (vp != NULL) {
if ((error = VOP_GETWRITEMOUNT(vp, mpp)) != 0) {
*mpp = NULL;
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 = *mpp) == NULL)
return (0);
/*
* VOP_GETWRITEMOUNT() returns with the mp refcount held through
* a vfs_ref().
* As long as a vnode is not provided we need to acquire a
* refcount for the provided mountpoint too, in order to
* emulate a vfs_ref().
*/
MNT_ILOCK(mp);
if (vp == NULL)
MNT_REF(mp);
if ((mp->mnt_kern_flag & (MNTK_SUSPENDED | MNTK_SUSPEND2)) == 0) {
mp->mnt_secondary_writes++;
mp->mnt_secondary_accwrites++;
MNT_IUNLOCK(mp);
return (0);
}
if (flags & V_NOWAIT) {
MNT_REL(mp);
MNT_IUNLOCK(mp);
return (EWOULDBLOCK);
}
/*
* Wait for the suspension to finish.
*/
error = msleep(&mp->mnt_flag, MNT_MTX(mp),
(PUSER - 1) | (flags & PCATCH) | PDROP, "suspfs", 0);
vfs_rel(mp);
if (error == 0)
goto retry;
return (error);
}
/*
* 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;
MNT_ILOCK(mp);
MNT_REL(mp);
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);
MNT_IUNLOCK(mp);
}
/*
* Filesystem secondary 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_secondary_write(mp)
struct mount *mp;
{
if (mp == NULL)
return;
MNT_ILOCK(mp);
MNT_REL(mp);
mp->mnt_secondary_writes--;
if (mp->mnt_secondary_writes < 0)
panic("vn_finished_secondary_write: neg cnt");
if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 &&
mp->mnt_secondary_writes <= 0)
wakeup(&mp->mnt_secondary_writes);
MNT_IUNLOCK(mp);
}
/*
* Request a filesystem to suspend write operations.
*/
int
vfs_write_suspend(struct mount *mp, int flags)
{
int error;
MNT_ILOCK(mp);
if (mp->mnt_susp_owner == curthread) {
MNT_IUNLOCK(mp);
return (EALREADY);
}
while (mp->mnt_kern_flag & MNTK_SUSPEND)
msleep(&mp->mnt_flag, MNT_MTX(mp), PUSER - 1, "wsuspfs", 0);
/*
* Unmount holds a write reference on the mount point. If we
* own busy reference and drain for writers, we deadlock with
* the reference draining in the unmount path. Callers of
* vfs_write_suspend() must specify VS_SKIP_UNMOUNT if
* vfs_busy() reference is owned and caller is not in the
* unmount context.
*/
if ((flags & VS_SKIP_UNMOUNT) != 0 &&
(mp->mnt_kern_flag & MNTK_UNMOUNT) != 0) {
MNT_IUNLOCK(mp);
return (EBUSY);
}
mp->mnt_kern_flag |= MNTK_SUSPEND;
mp->mnt_susp_owner = curthread;
if (mp->mnt_writeopcount > 0)
(void) msleep(&mp->mnt_writeopcount,
MNT_MTX(mp), (PUSER - 1)|PDROP, "suspwt", 0);
else
MNT_IUNLOCK(mp);
if ((error = VFS_SYNC(mp, MNT_SUSPEND)) != 0)
vfs_write_resume(mp, 0);
return (error);
}
/*
* Request a filesystem to resume write operations.
*/
void
vfs_write_resume(struct mount *mp, int flags)
{
MNT_ILOCK(mp);
if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
KASSERT(mp->mnt_susp_owner == curthread, ("mnt_susp_owner"));
mp->mnt_kern_flag &= ~(MNTK_SUSPEND | MNTK_SUSPEND2 |
MNTK_SUSPENDED);
mp->mnt_susp_owner = NULL;
wakeup(&mp->mnt_writeopcount);
wakeup(&mp->mnt_flag);
curthread->td_pflags &= ~TDP_IGNSUSP;
if ((flags & VR_START_WRITE) != 0) {
MNT_REF(mp);
mp->mnt_writeopcount++;
}
MNT_IUNLOCK(mp);
if ((flags & VR_NO_SUSPCLR) == 0)
VFS_SUSP_CLEAN(mp);
} else if ((flags & VR_START_WRITE) != 0) {
MNT_REF(mp);
vn_start_write_locked(mp, 0);
} else {
MNT_IUNLOCK(mp);
}
}
/*
* Implement kqueues for files by translating it to vnode operation.
*/
static int
vn_kqfilter(struct file *fp, struct knote *kn)
{
return (VOP_KQFILTER(fp->f_vnode, kn));
}
/*
* Simplified in-kernel wrapper calls for extended attribute access.
* Both calls pass in a NULL credential, authorizing as "kernel" access.
* Set IO_NODELOCKED in ioflg if the vnode is already locked.
*/
int
vn_extattr_get(struct vnode *vp, int ioflg, int attrnamespace,
const char *attrname, int *buflen, char *buf, struct thread *td)
{
struct uio auio;
struct iovec iov;
int error;
iov.iov_len = *buflen;
iov.iov_base = buf;
auio.uio_iov = &iov;
auio.uio_iovcnt = 1;
auio.uio_rw = UIO_READ;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_td = td;
auio.uio_offset = 0;
auio.uio_resid = *buflen;
if ((ioflg & IO_NODELOCKED) == 0)
vn_lock(vp, LK_SHARED | LK_RETRY);
ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
/* authorize attribute retrieval as kernel */
error = VOP_GETEXTATTR(vp, attrnamespace, attrname, &auio, NULL, NULL,
td);
if ((ioflg & IO_NODELOCKED) == 0)
VOP_UNLOCK(vp, 0);
if (error == 0) {
*buflen = *buflen - auio.uio_resid;
}
return (error);
}
/*
* XXX failure mode if partially written?
*/
int
vn_extattr_set(struct vnode *vp, int ioflg, int attrnamespace,
const char *attrname, int buflen, char *buf, struct thread *td)
{
struct uio auio;
struct iovec iov;
struct mount *mp;
int error;
iov.iov_len = buflen;
iov.iov_base = buf;
auio.uio_iov = &iov;
auio.uio_iovcnt = 1;
auio.uio_rw = UIO_WRITE;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_td = td;
auio.uio_offset = 0;
auio.uio_resid = buflen;
if ((ioflg & IO_NODELOCKED) == 0) {
if ((error = vn_start_write(vp, &mp, V_WAIT)) != 0)
return (error);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
}
ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
/* authorize attribute setting as kernel */
error = VOP_SETEXTATTR(vp, attrnamespace, attrname, &auio, NULL, td);
if ((ioflg & IO_NODELOCKED) == 0) {
vn_finished_write(mp);
VOP_UNLOCK(vp, 0);
}
return (error);
}
int
vn_extattr_rm(struct vnode *vp, int ioflg, int attrnamespace,
const char *attrname, struct thread *td)
{
struct mount *mp;
int error;
if ((ioflg & IO_NODELOCKED) == 0) {
if ((error = vn_start_write(vp, &mp, V_WAIT)) != 0)
return (error);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
}
ASSERT_VOP_LOCKED(vp, "IO_NODELOCKED with no vp lock held");
/* authorize attribute removal as kernel */
error = VOP_DELETEEXTATTR(vp, attrnamespace, attrname, NULL, td);
if (error == EOPNOTSUPP)
error = VOP_SETEXTATTR(vp, attrnamespace, attrname, NULL,
NULL, td);
if ((ioflg & IO_NODELOCKED) == 0) {
vn_finished_write(mp);
VOP_UNLOCK(vp, 0);
}
return (error);
}
int
vn_vget_ino(struct vnode *vp, ino_t ino, int lkflags, struct vnode **rvp)
{
struct mount *mp;
int ltype, error;
mp = vp->v_mount;
ltype = VOP_ISLOCKED(vp);
KASSERT(ltype == LK_EXCLUSIVE || ltype == LK_SHARED,
("vn_vget_ino: vp not locked"));
error = vfs_busy(mp, MBF_NOWAIT);
if (error != 0) {
vfs_ref(mp);
VOP_UNLOCK(vp, 0);
error = vfs_busy(mp, 0);
vn_lock(vp, ltype | LK_RETRY);
vfs_rel(mp);
if (error != 0)
return (ENOENT);
if (vp->v_iflag & VI_DOOMED) {
vfs_unbusy(mp);
return (ENOENT);
}
}
VOP_UNLOCK(vp, 0);
error = VFS_VGET(mp, ino, lkflags, rvp);
vfs_unbusy(mp);
vn_lock(vp, ltype | LK_RETRY);
if (vp->v_iflag & VI_DOOMED) {
if (error == 0)
vput(*rvp);
error = ENOENT;
}
return (error);
}
int
vn_rlimit_fsize(const struct vnode *vp, const struct uio *uio,
const struct thread *td)
{
if (vp->v_type != VREG || td == NULL)
return (0);
PROC_LOCK(td->td_proc);
if ((uoff_t)uio->uio_offset + uio->uio_resid >
lim_cur(td->td_proc, RLIMIT_FSIZE)) {
kern_psignal(td->td_proc, SIGXFSZ);
PROC_UNLOCK(td->td_proc);
return (EFBIG);
}
PROC_UNLOCK(td->td_proc);
return (0);
}
int
vn_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
struct thread *td)
{
struct vnode *vp;
vp = fp->f_vnode;
#ifdef AUDIT
vn_lock(vp, LK_SHARED | LK_RETRY);
AUDIT_ARG_VNODE1(vp);
VOP_UNLOCK(vp, 0);
#endif
return (setfmode(td, active_cred, vp, mode));
}
int
vn_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
struct thread *td)
{
struct vnode *vp;
vp = fp->f_vnode;
#ifdef AUDIT
vn_lock(vp, LK_SHARED | LK_RETRY);
AUDIT_ARG_VNODE1(vp);
VOP_UNLOCK(vp, 0);
#endif
return (setfown(td, active_cred, vp, uid, gid));
}
void
vn_pages_remove(struct vnode *vp, vm_pindex_t start, vm_pindex_t end)
{
vm_object_t object;
if ((object = vp->v_object) == NULL)
return;
VM_OBJECT_WLOCK(object);
vm_object_page_remove(object, start, end, 0);
VM_OBJECT_WUNLOCK(object);
}
int
vn_bmap_seekhole(struct vnode *vp, u_long cmd, off_t *off, struct ucred *cred)
{
struct vattr va;
daddr_t bn, bnp;
uint64_t bsize;
off_t noff;
int error;
KASSERT(cmd == FIOSEEKHOLE || cmd == FIOSEEKDATA,
("Wrong command %lu", cmd));
if (vn_lock(vp, LK_SHARED) != 0)
return (EBADF);
if (vp->v_type != VREG) {
error = ENOTTY;
goto unlock;
}
error = VOP_GETATTR(vp, &va, cred);
if (error != 0)
goto unlock;
noff = *off;
if (noff >= va.va_size) {
error = ENXIO;
goto unlock;
}
bsize = vp->v_mount->mnt_stat.f_iosize;
for (bn = noff / bsize; noff < va.va_size; bn++, noff += bsize) {
error = VOP_BMAP(vp, bn, NULL, &bnp, NULL, NULL);
if (error == EOPNOTSUPP) {
error = ENOTTY;
goto unlock;
}
if ((bnp == -1 && cmd == FIOSEEKHOLE) ||
(bnp != -1 && cmd == FIOSEEKDATA)) {
noff = bn * bsize;
if (noff < *off)
noff = *off;
goto unlock;
}
}
if (noff > va.va_size)
noff = va.va_size;
/* noff == va.va_size. There is an implicit hole at the end of file. */
if (cmd == FIOSEEKDATA)
error = ENXIO;
unlock:
VOP_UNLOCK(vp, 0);
if (error == 0)
*off = noff;
return (error);
}
int
vn_seek(struct file *fp, off_t offset, int whence, struct thread *td)
{
struct ucred *cred;
struct vnode *vp;
struct vattr vattr;
off_t foffset, size;
int error, noneg;
cred = td->td_ucred;
vp = fp->f_vnode;
foffset = foffset_lock(fp, 0);
noneg = (vp->v_type != VCHR);
error = 0;
switch (whence) {
case L_INCR:
if (noneg &&
(foffset < 0 ||
(offset > 0 && foffset > OFF_MAX - offset))) {
error = EOVERFLOW;
break;
}
offset += foffset;
break;
case L_XTND:
vn_lock(vp, LK_SHARED | LK_RETRY);
error = VOP_GETATTR(vp, &vattr, cred);
VOP_UNLOCK(vp, 0);
if (error)
break;
/*
* If the file references a disk device, then fetch
* the media size and use that to determine the ending
* offset.
*/
if (vattr.va_size == 0 && vp->v_type == VCHR &&
fo_ioctl(fp, DIOCGMEDIASIZE, &size, cred, td) == 0)
vattr.va_size = size;
if (noneg &&
(vattr.va_size > OFF_MAX ||
(offset > 0 && vattr.va_size > OFF_MAX - offset))) {
error = EOVERFLOW;
break;
}
offset += vattr.va_size;
break;
case L_SET:
break;
case SEEK_DATA:
error = fo_ioctl(fp, FIOSEEKDATA, &offset, cred, td);
break;
case SEEK_HOLE:
error = fo_ioctl(fp, FIOSEEKHOLE, &offset, cred, td);
break;
default:
error = EINVAL;
}
if (error == 0 && noneg && offset < 0)
error = EINVAL;
if (error != 0)
goto drop;
VFS_KNOTE_UNLOCKED(vp, 0);
*(off_t *)(td->td_retval) = offset;
drop:
foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
return (error);
}
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