Add two new states FSS_CREATING and FSS_DESTROYING and use them
while creating or destroying a snapshot. Remove now unneeded sc_lock that made fss_ioctl mutually exclusive. Fss_ioctl no longer blocks forever because a snapshot gets created or destroyed. Serialize snapshot creation and make it interruptible.
This commit is contained in:
hannken
parent
1624e66471
commit
bdbfbc99b0
106
sys/dev/fss.c
106
sys/dev/fss.c
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@ -1,4 +1,4 @@
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/* $NetBSD: fss.c,v 1.105 2018/08/29 09:04:03 hannken Exp $ */
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/* $NetBSD: fss.c,v 1.106 2018/08/29 09:04:40 hannken Exp $ */
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/*-
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* Copyright (c) 2003 The NetBSD Foundation, Inc.
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@ -36,7 +36,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.105 2018/08/29 09:04:03 hannken Exp $");
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__KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.106 2018/08/29 09:04:40 hannken Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -93,6 +93,8 @@ static int fss_bs_io(struct fss_softc *, fss_io_type,
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static u_int32_t *fss_bs_indir(struct fss_softc *, u_int32_t);
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static kmutex_t fss_device_lock; /* Protect all units. */
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static kcondvar_t fss_device_cv; /* Serialize snapshot creation. */
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static bool fss_creating = false; /* Currently creating a snapshot. */
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static int fss_num_attached = 0; /* Number of attached devices. */
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static struct vfs_hooks fss_vfs_hooks = {
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.vh_unmount = fss_unmount_hook
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@ -136,6 +138,7 @@ fssattach(int num)
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{
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mutex_init(&fss_device_lock, MUTEX_DEFAULT, IPL_NONE);
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cv_init(&fss_device_cv, "snapwait");
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if (config_cfattach_attach(fss_cd.cd_name, &fss_ca))
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aprint_error("%s: unable to register\n", fss_cd.cd_name);
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}
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@ -154,7 +157,6 @@ fss_attach(device_t parent, device_t self, void *aux)
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sc->sc_dev = self;
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sc->sc_bdev = NODEV;
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mutex_init(&sc->sc_slock, MUTEX_DEFAULT, IPL_NONE);
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mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NONE);
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cv_init(&sc->sc_work_cv, "fssbs");
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cv_init(&sc->sc_cache_cv, "cowwait");
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bufq_alloc(&sc->sc_bufq, "fcfs", 0);
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@ -185,7 +187,6 @@ fss_detach(device_t self, int flags)
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pmf_device_deregister(self);
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mutex_destroy(&sc->sc_slock);
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mutex_destroy(&sc->sc_lock);
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cv_destroy(&sc->sc_work_cv);
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cv_destroy(&sc->sc_cache_cv);
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bufq_drain(sc->sc_bufq);
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@ -341,36 +342,83 @@ fss_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
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fss->fss_flags = 0;
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/* Fall through */
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case FSSIOCSET:
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mutex_enter(&sc->sc_lock);
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mutex_enter(&sc->sc_slock);
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if ((flag & FWRITE) == 0)
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error = EPERM;
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mutex_enter(&sc->sc_slock);
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if (error == 0 && sc->sc_state != FSS_IDLE)
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if (error == 0 && sc->sc_state != FSS_IDLE) {
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error = EBUSY;
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} else {
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sc->sc_state = FSS_CREATING;
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copyinstr(fss->fss_mount, sc->sc_mntname,
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sizeof(sc->sc_mntname), NULL);
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memset(&sc->sc_time, 0, sizeof(sc->sc_time));
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sc->sc_clshift = 0;
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}
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mutex_exit(&sc->sc_slock);
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if (error == 0)
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error = fss_create_snapshot(sc, fss, l);
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if (error == 0)
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if (error)
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break;
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/*
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* Serialize snapshot creation.
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*/
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mutex_enter(&fss_device_lock);
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while (fss_creating) {
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error = cv_wait_sig(&fss_device_cv, &fss_device_lock);
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if (error) {
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mutex_enter(&sc->sc_slock);
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KASSERT(sc->sc_state == FSS_CREATING);
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sc->sc_state = FSS_IDLE;
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mutex_exit(&sc->sc_slock);
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mutex_exit(&fss_device_lock);
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break;
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}
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}
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fss_creating = true;
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mutex_exit(&fss_device_lock);
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error = fss_create_snapshot(sc, fss, l);
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mutex_enter(&sc->sc_slock);
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if (error == 0) {
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KASSERT(sc->sc_state == FSS_ACTIVE);
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sc->sc_uflags = fss->fss_flags;
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mutex_exit(&sc->sc_lock);
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} else {
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KASSERT(sc->sc_state == FSS_CREATING);
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sc->sc_state = FSS_IDLE;
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}
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mutex_exit(&sc->sc_slock);
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mutex_enter(&fss_device_lock);
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fss_creating = false;
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cv_broadcast(&fss_device_cv);
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mutex_exit(&fss_device_lock);
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break;
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case FSSIOCCLR:
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mutex_enter(&sc->sc_lock);
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if ((flag & FWRITE) == 0)
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error = EPERM;
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mutex_enter(&sc->sc_slock);
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if (error == 0 && sc->sc_state == FSS_IDLE)
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error = ENXIO;
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if ((flag & FWRITE) == 0) {
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error = EPERM;
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} else if (sc->sc_state != FSS_ACTIVE &&
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sc->sc_state != FSS_ERROR) {
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error = EBUSY;
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} else {
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sc->sc_state = FSS_DESTROYING;
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}
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mutex_exit(&sc->sc_slock);
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if (error)
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break;
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error = fss_delete_snapshot(sc, l);
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mutex_enter(&sc->sc_slock);
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if (error)
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fss_error(sc, "Failed to delete snapshot");
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else
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KASSERT(sc->sc_state == FSS_IDLE);
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mutex_exit(&sc->sc_slock);
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if (error == 0)
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error = fss_delete_snapshot(sc, l);
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mutex_exit(&sc->sc_lock);
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break;
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#ifndef _LP64
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case FSSIOCGET50:
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mutex_enter(&sc->sc_lock);
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mutex_enter(&sc->sc_slock);
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if (sc->sc_state == FSS_IDLE) {
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error = ENXIO;
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@ -390,12 +438,10 @@ fss_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
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error = 0;
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}
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mutex_exit(&sc->sc_slock);
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mutex_exit(&sc->sc_lock);
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break;
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#endif /* _LP64 */
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case FSSIOCGET:
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mutex_enter(&sc->sc_lock);
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mutex_enter(&sc->sc_slock);
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if (sc->sc_state == FSS_IDLE) {
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error = ENXIO;
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@ -415,7 +461,6 @@ fss_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
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error = 0;
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}
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mutex_exit(&sc->sc_slock);
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mutex_exit(&sc->sc_lock);
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break;
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case FSSIOFSET:
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@ -902,20 +947,23 @@ fss_delete_snapshot(struct fss_softc *sc, struct lwp *l)
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if ((sc->sc_flags & FSS_PERSISTENT) == 0 && sc->sc_state != FSS_ERROR) {
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mutex_exit(&sc->sc_slock);
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fscow_disestablish(sc->sc_mount, fss_copy_on_write, sc);
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mutex_enter(&sc->sc_slock);
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} else {
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mutex_exit(&sc->sc_slock);
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}
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sc->sc_state = FSS_IDLE;
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sc->sc_mount = NULL;
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sc->sc_bdev = NODEV;
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mutex_exit(&sc->sc_slock);
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fss_softc_free(sc);
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if (sc->sc_flags & FSS_PERSISTENT)
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vrele(sc->sc_bs_vp);
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else
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vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred);
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mutex_enter(&sc->sc_slock);
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sc->sc_state = FSS_IDLE;
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sc->sc_mount = NULL;
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sc->sc_bdev = NODEV;
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sc->sc_bs_vp = NULL;
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sc->sc_flags &= ~FSS_PERSISTENT;
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mutex_exit(&sc->sc_slock);
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return 0;
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}
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@ -1323,6 +1371,7 @@ fss_modcmd(modcmd_t cmd, void *arg)
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switch (cmd) {
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case MODULE_CMD_INIT:
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mutex_init(&fss_device_lock, MUTEX_DEFAULT, IPL_NONE);
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cv_init(&fss_device_cv, "snapwait");
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error = config_cfdriver_attach(&fss_cd);
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if (error) {
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mutex_destroy(&fss_device_lock);
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@ -1361,6 +1410,7 @@ fss_modcmd(modcmd_t cmd, void *arg)
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&fss_cdevsw, &fss_cmajor);
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break;
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}
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cv_destroy(&fss_device_cv);
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mutex_destroy(&fss_device_lock);
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break;
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@ -1,4 +1,4 @@
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/* $NetBSD: fssvar.h,v 1.30 2018/08/29 09:04:03 hannken Exp $ */
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/* $NetBSD: fssvar.h,v 1.31 2018/08/29 09:04:40 hannken Exp $ */
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/*-
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* Copyright (c) 2003, 2007 The NetBSD Foundation, Inc.
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@ -135,14 +135,15 @@ struct fss_cache {
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typedef enum {
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FSS_IDLE, /* Device is unconfigured */
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FSS_CREATING, /* Device is currently configuring */
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FSS_ACTIVE, /* Device is configured */
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FSS_DESTROYING, /* Device is currently unconfiguring */
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FSS_ERROR /* Device had errors */
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} fss_state_t;
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struct fss_softc {
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device_t sc_dev; /* Self */
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kmutex_t sc_slock; /* Protect this softc */
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kmutex_t sc_lock; /* Sleep lock for fss_ioctl */
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kcondvar_t sc_work_cv; /* Signals work for the kernel thread */
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kcondvar_t sc_cache_cv; /* Signals free cache slot */
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fss_state_t sc_state; /* Current state */
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