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- Conditionally acquire Giant in mdstart_vnode(), mdcreate_vnode(), and

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mddestroy() only if the file is from a non-MPSAFE VFS.
- No longer unconditionally hold Giant in the md kthread for vnode-backed
  kthreads.
- Improve the handling of the thread exit race when destroying an md
  device.
This commit is contained in:
John Baldwin 2006-03-28 21:25:11 +00:00
parent 861dab08e7
commit a08d2e7fe1
1 changed files with 23 additions and 29 deletions
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52
sys/dev/md/md.c
View File

@ -67,6 +67,7 @@
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mdioctl.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/sx.h>
#include <sys/namei.h>
@ -88,7 +89,8 @@
#define MD_MODVER 1
#define MD_SHUTDOWN 0x10000 /* Tell worker thread to terminate. */
#define MD_SHUTDOWN 0x10000 /* Tell worker thread to terminate. */
#define MD_EXITING 0x20000 /* Worker thread is exiting. */
#ifndef MD_NSECT
#define MD_NSECT (10000 * 2)
@ -485,12 +487,11 @@ mdstart_preload(struct md_s *sc, struct bio *bp)
static int
mdstart_vnode(struct md_s *sc, struct bio *bp)
{
int error;
int error, vfslocked;
struct uio auio;
struct iovec aiov;
struct mount *mp;
mtx_assert(&Giant, MA_OWNED);
/*
* VNODE I/O
*
@ -519,6 +520,7 @@ mdstart_vnode(struct md_s *sc, struct bio *bp)
* When reading set IO_DIRECT to try to avoid double-caching
* the data. When writing IO_DIRECT is not optimal.
*/
vfslocked = VFS_LOCK_GIANT(sc->vnode->v_mount);
if (bp->bio_cmd == BIO_READ) {
vn_lock(sc->vnode, LK_EXCLUSIVE | LK_RETRY, curthread);
error = VOP_READ(sc->vnode, &auio, IO_DIRECT, sc->cred);
@ -531,6 +533,7 @@ mdstart_vnode(struct md_s *sc, struct bio *bp)
VOP_UNLOCK(sc->vnode, 0, curthread);
vn_finished_write(mp);
}
VFS_UNLOCK_GIANT(vfslocked);
bp->bio_resid = auio.uio_resid;
return (error);
}
@ -641,35 +644,20 @@ md_kthread(void *arg)
{
struct md_s *sc;
struct bio *bp;
int error, hasgiant;
int error;
sc = arg;
mtx_lock_spin(&sched_lock);
sched_prio(curthread, PRIBIO);
mtx_unlock_spin(&sched_lock);
switch (sc->type) {
case MD_VNODE:
mtx_lock(&Giant);
hasgiant = 1;
break;
case MD_MALLOC:
case MD_PRELOAD:
case MD_SWAP:
default:
hasgiant = 0;
break;
}
for (;;) {
mtx_lock(&sc->queue_mtx);
if (sc->flags & MD_SHUTDOWN) {
sc->procp = NULL;
wakeup(&sc->procp);
if (hasgiant)
mtx_unlock(&Giant);
sc->flags |= MD_EXITING;
mtx_unlock(&sc->queue_mtx);
kthread_exit(0);
}
mtx_lock(&sc->queue_mtx);
bp = bioq_takefirst(&sc->bio_queue);
if (!bp) {
msleep(sc, &sc->queue_mtx, PRIBIO | PDROP, "mdwait", 0);
@ -867,7 +855,7 @@ mdcreate_vnode(struct md_s *sc, struct md_ioctl *mdio, struct thread *td)
{
struct vattr vattr;
struct nameidata nd;
int error, flags;
int error, flags, vfslocked;
error = copyinstr(mdio->md_file, sc->file, sizeof(sc->file), NULL);
if (error != 0)
@ -879,15 +867,17 @@ mdcreate_vnode(struct md_s *sc, struct md_ioctl *mdio, struct thread *td)
*/
if ((mdio->md_options & MD_READONLY) != 0)
flags &= ~FWRITE;
NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, sc->file, td);
NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, sc->file, td);
error = vn_open(&nd, &flags, 0, -1);
if (error != 0)
return (error);
vfslocked = NDHASGIANT(&nd);
NDFREE(&nd, NDF_ONLY_PNBUF);
if (nd.ni_vp->v_type != VREG ||
(error = VOP_GETATTR(nd.ni_vp, &vattr, td->td_ucred, td))) {
VOP_UNLOCK(nd.ni_vp, 0, td);
(void)vn_close(nd.ni_vp, flags, td->td_ucred, td);
VFS_UNLOCK_GIANT(vfslocked);
return (error ? error : EINVAL);
}
VOP_UNLOCK(nd.ni_vp, 0, td);
@ -904,15 +894,17 @@ mdcreate_vnode(struct md_s *sc, struct md_ioctl *mdio, struct thread *td)
error = mdsetcred(sc, td->td_ucred);
if (error != 0) {
(void)vn_close(nd.ni_vp, flags, td->td_ucred, td);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
VFS_UNLOCK_GIANT(vfslocked);
return (0);
}
static int
mddestroy(struct md_s *sc, struct thread *td)
{
int vfslocked;
if (sc->gp) {
sc->gp->softc = NULL;
@ -922,16 +914,18 @@ mddestroy(struct md_s *sc, struct thread *td)
sc->gp = NULL;
sc->pp = NULL;
}
mtx_lock(&sc->queue_mtx);
sc->flags |= MD_SHUTDOWN;
wakeup(sc);
while (sc->procp != NULL)
tsleep(&sc->procp, PRIBIO, "mddestroy", hz / 10);
while (!(sc->flags & MD_EXITING))
msleep(sc->procp, &sc->queue_mtx, PRIBIO, "mddestroy", hz / 10);
mtx_unlock(&sc->queue_mtx);
mtx_destroy(&sc->queue_mtx);
if (sc->vnode != NULL) {
mtx_lock(&Giant);
vfslocked = VFS_LOCK_GIANT(sc->vnode->v_mount);
(void)vn_close(sc->vnode, sc->flags & MD_READONLY ?
FREAD : (FREAD|FWRITE), sc->cred, td);
mtx_unlock(&Giant);
VFS_UNLOCK_GIANT(vfslocked);
}
if (sc->cred != NULL)
crfree(sc->cred);