svn commit: r268015 - stable/10/sys/kern
Konstantin Belousov
kib at FreeBSD.org
Sun Jun 29 07:02:48 UTC 2014
Author: kib
Date: Sun Jun 29 07:02:47 2014
New Revision: 268015
URL: http://svnweb.freebsd.org/changeset/base/268015
Log:
MFC r267491:
Use vn_io_fault for the writes from core dumping code.
Modified:
stable/10/sys/kern/vfs_vnops.c
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/kern/vfs_vnops.c
==============================================================================
--- stable/10/sys/kern/vfs_vnops.c Sun Jun 29 02:28:05 2014 (r268014)
+++ stable/10/sys/kern/vfs_vnops.c Sun Jun 29 07:02:47 2014 (r268015)
@@ -8,7 +8,7 @@
* the permission of UNIX System Laboratories, Inc.
*
* Copyright (c) 2012 Konstantin Belousov <kib at FreeBSD.org>
- * Copyright (c) 2013 The FreeBSD Foundation
+ * Copyright (c) 2013, 2014 The FreeBSD Foundation
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
@@ -106,6 +106,53 @@ struct fileops vnops = {
.fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
};
+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");
+
+/*
+ * Returns true if vn_io_fault mode of handling the i/o request should
+ * be used.
+ */
+static bool
+do_vn_io_fault(struct vnode *vp, struct uio *uio)
+{
+ struct mount *mp;
+
+ return (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);
+}
+
+/*
+ * Structure used to pass arguments to vn_io_fault1(), to do either
+ * file- or vnode-based I/O calls.
+ */
+struct vn_io_fault_args {
+ enum {
+ VN_IO_FAULT_FOP,
+ VN_IO_FAULT_VOP
+ } kind;
+ struct ucred *cred;
+ int flags;
+ union {
+ struct fop_args_tag {
+ struct file *fp;
+ fo_rdwr_t *doio;
+ } fop_args;
+ struct vop_args_tag {
+ struct vnode *vp;
+ } vop_args;
+ } args;
+};
+
+static int vn_io_fault1(struct vnode *vp, struct uio *uio,
+ struct vn_io_fault_args *args, struct thread *td);
+
int
vn_open(ndp, flagp, cmode, fp)
struct nameidata *ndp;
@@ -439,6 +486,7 @@ vn_rdwr(enum uio_rw rw, struct vnode *vp
struct mount *mp;
struct ucred *cred;
void *rl_cookie;
+ struct vn_io_fault_args args;
int error, lock_flags;
auio.uio_iov = &aiov;
@@ -493,10 +541,17 @@ vn_rdwr(enum uio_rw rw, struct vnode *vp
cred = file_cred;
else
cred = active_cred;
- if (rw == UIO_READ)
+ if (do_vn_io_fault(vp, &auio)) {
+ args.kind = VN_IO_FAULT_VOP;
+ args.cred = cred;
+ args.flags = ioflg;
+ args.args.vop_args.vp = vp;
+ error = vn_io_fault1(vp, &auio, &args, td);
+ } else if (rw == UIO_READ) {
error = VOP_READ(vp, &auio, ioflg, cred);
- else
+ } else /* if (rw == UIO_WRITE) */ {
error = VOP_WRITE(vp, &auio, ioflg, cred);
+ }
}
if (aresid)
*aresid = auio.uio_resid;
@@ -883,14 +938,6 @@ 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:
@@ -924,38 +971,55 @@ SYSCTL_ULONG(_debug, OID_AUTO, vn_io_fau
* make the current i/o request atomic with respect to other i/os and
* truncations.
*/
+
+/*
+ * Decode vn_io_fault_args and perform the corresponding i/o.
+ */
static int
-vn_io_fault(struct file *fp, struct uio *uio, struct ucred *active_cred,
- int flags, struct thread *td)
+vn_io_fault_doio(struct vn_io_fault_args *args, struct uio *uio,
+ struct thread *td)
+{
+
+ switch (args->kind) {
+ case VN_IO_FAULT_FOP:
+ return ((args->args.fop_args.doio)(args->args.fop_args.fp,
+ uio, args->cred, args->flags, td));
+ case VN_IO_FAULT_VOP:
+ if (uio->uio_rw == UIO_READ) {
+ return (VOP_READ(args->args.vop_args.vp, uio,
+ args->flags, args->cred));
+ } else if (uio->uio_rw == UIO_WRITE) {
+ return (VOP_WRITE(args->args.vop_args.vp, uio,
+ args->flags, args->cred));
+ }
+ break;
+ }
+ panic("vn_io_fault_doio: unknown kind of io %d %d", args->kind,
+ uio->uio_rw);
+}
+
+/*
+ * Common code for vn_io_fault(), agnostic to the kind of i/o request.
+ * Uses vn_io_fault_doio() to make the call to an actual i/o function.
+ * Used from vn_rdwr() and vn_io_fault(), which encode the i/o request
+ * into args and call vn_io_fault1() to handle faults during the user
+ * mode buffer accesses.
+ */
+static int
+vn_io_fault1(struct vnode *vp, struct uio *uio, struct vn_io_fault_args *args,
+ 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 error, cnt, save, saveheld, prev_td_ma_cnt;
- vm_offset_t addr, end;
vm_prot_t prot;
+ vm_offset_t addr, end;
size_t len, resid;
ssize_t adv;
+ int error, cnt, save, saveheld, prev_td_ma_cnt;
- 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;
- }
+ prot = uio->uio_rw == UIO_READ ? VM_PROT_WRITE : VM_PROT_READ;
/*
* The UFS follows IO_UNIT directive and replays back both
@@ -973,22 +1037,8 @@ vn_io_fault(struct file *fp, struct uio
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);
+ error = vn_io_fault_doio(args, uio, td);
if (error != EFAULT)
goto out;
@@ -1038,8 +1088,7 @@ vn_io_fault(struct file *fp, struct uio
td->td_ma = ma;
td->td_ma_cnt = cnt;
- error = doio(fp, &short_uio, active_cred, flags | FOF_OFFSET,
- td);
+ error = vn_io_fault_doio(args, &short_uio, td);
vm_page_unhold_pages(ma, cnt);
adv = len - short_uio.uio_resid;
@@ -1060,9 +1109,45 @@ vn_io_fault(struct file *fp, struct uio
curthread_pflags_restore(saveheld);
out:
vm_fault_enable_pagefaults(save);
- vn_rangelock_unlock(vp, rl_cookie);
free(uio_clone, M_IOV);
-out_last:
+ return (error);
+}
+
+static int
+vn_io_fault(struct file *fp, struct uio *uio, struct ucred *active_cred,
+ int flags, struct thread *td)
+{
+ fo_rdwr_t *doio;
+ struct vnode *vp;
+ void *rl_cookie;
+ struct vn_io_fault_args args;
+ int error;
+
+ doio = uio->uio_rw == UIO_READ ? vn_read : vn_write;
+ vp = fp->f_vnode;
+ foffset_lock_uio(fp, uio, flags);
+ if (do_vn_io_fault(vp, uio)) {
+ args.kind = VN_IO_FAULT_FOP;
+ args.args.fop_args.fp = fp;
+ args.args.fop_args.doio = doio;
+ args.cred = active_cred;
+ args.flags = flags | FOF_OFFSET;
+ if (uio->uio_rw == UIO_READ) {
+ rl_cookie = vn_rangelock_rlock(vp, uio->uio_offset,
+ uio->uio_offset + uio->uio_resid);
+ } else 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);
+ }
+ error = vn_io_fault1(vp, uio, &args, td);
+ vn_rangelock_unlock(vp, rl_cookie);
+ } else {
+ error = doio(fp, uio, active_cred, flags | FOF_OFFSET, td);
+ }
foffset_unlock_uio(fp, uio, flags);
return (error);
}
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