Date: Fri, 13 Mar 2015 21:07:05 +0100 From: Mateusz Guzik <mjguzik@gmail.com> To: Tiwei Bie <btw@mail.ustc.edu.cn> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Ryan Stone <rysto32@gmail.com>, wca@freebsd.org Subject: Re: [PATCH] Finish the task 'Convert mountlist_mtx to rwlock' Message-ID: <20150313200705.GA32157@dft-labs.eu> In-Reply-To: <20150312132338.GA57932@freebsd> References: <1426079434-51568-1-git-send-email-btw@mail.ustc.edu.cn> <CAFMmRNyLJgLuk-VPSuyBCpO1bkdmyGf3s89X-An1vCCMwn=B=A@mail.gmail.com> <20150312132338.GA57932@freebsd>
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On Thu, Mar 12, 2015 at 09:26:00PM +0800, Tiwei Bie wrote:
> On Thu, Mar 12, 2015 at 12:06:02AM -0400, Ryan Stone wrote:
> > On Wed, Mar 11, 2015 at 9:10 AM, Tiwei Bie <btw@mail.ustc.edu.cn> wrote:
> > > Hi, Mateusz!
> > >
> > > I have finished the task: Convert mountlist_mtx to rwlock [1].
> >
> > My first comment is, are we sure that we actually want an rwlock here
> > instead of an rmlock? An rmlock will offer much better performance in
> > workloads that mostly only take read locks, and rmlocks do not suffer
> > the priority inversion problems that rwlocks do. From the description
> > on the wiki page, it sounds like an rmlock would be ideal here:
> >
> > > Interested person can upgrade this task to non-junior by coming up with a
> > > solution exploiting rare need to modify the list. Example approaches include
> > > designing a locking primitive with cheap shared locking (think: per-cpu) at
> > > the expense of exclusive locking.
> >
>
> I think rmlock is okay. But one more argument needs to be added
> to vfs_busy(), that is 'struct rm_priotracker *tracker' which is
> used to track read owners of mountlist_lock in vfs_busy().
So, this is not a simple s/rw_lock/rm_rlock and the like after all, sorry. :)
I'll have to go over this and possibly gather some ACKs before
committing.
>
> Following is my patch:
>
> ---
> share/man/man9/vfs_busy.9 | 7 ++-
> .../compat/opensolaris/kern/opensolaris_lookup.c | 2 +-
> sys/cddl/compat/opensolaris/kern/opensolaris_vfs.c | 5 ++-
> .../opensolaris/uts/common/fs/zfs/zfs_ioctl.c | 6 ++-
> .../opensolaris/uts/common/fs/zfs/zfs_vfsops.c | 6 ++-
> sys/compat/linprocfs/linprocfs.c | 6 ++-
> sys/fs/fuse/fuse_vnops.c | 4 +-
> sys/fs/nfsclient/nfs_clstate.c | 2 +-
> sys/fs/nfsclient/nfs_clvfsops.c | 2 +-
> sys/fs/nfsclient/nfs_clvnops.c | 4 +-
> sys/fs/nfsserver/nfs_nfsdport.c | 4 +-
> sys/fs/nfsserver/nfs_nfsdserv.c | 2 +-
> sys/fs/pseudofs/pseudofs_vnops.c | 6 +--
> sys/fs/smbfs/smbfs_vnops.c | 4 +-
> sys/fs/tmpfs/tmpfs_vnops.c | 2 +-
> sys/geom/journal/g_journal.c | 13 +++---
> sys/kern/vfs_extattr.c | 2 +-
> sys/kern/vfs_lookup.c | 2 +-
> sys/kern/vfs_mount.c | 26 ++++++-----
> sys/kern/vfs_mountroot.c | 14 +++---
> sys/kern/vfs_subr.c | 51 ++++++++++++----------
> sys/kern/vfs_syscalls.c | 33 +++++++-------
> sys/kern/vfs_vnops.c | 4 +-
> sys/sys/mount.h | 8 ++--
> sys/ufs/ffs/ffs_softdep.c | 8 ++--
> sys/ufs/ffs/ffs_suspend.c | 2 +-
> sys/ufs/ufs/ufs_quota.c | 2 +-
> 27 files changed, 127 insertions(+), 100 deletions(-)
>
> diff --git a/share/man/man9/vfs_busy.9 b/share/man/man9/vfs_busy.9
> index 8b9ba86..155e1e6 100644
> --- a/share/man/man9/vfs_busy.9
> +++ b/share/man/man9/vfs_busy.9
> @@ -36,7 +36,7 @@
> .In sys/param.h
> .In sys/mount.h
> .Ft int
> -.Fn vfs_busy "struct mount *mp" "int flags"
> +.Fn vfs_busy "struct mount *mp" "int flags" "struct rm_priotracker *tracker"
> .Sh DESCRIPTION
> The
> .Fn vfs_busy
> @@ -68,8 +68,11 @@ do not sleep if
> .Dv MNTK_UNMOUNT
> is set.
> .It Dv MBF_MNTLSTLOCK
> -drop the mountlist_mtx in the critical path.
> +drop the mountlist_lock in the critical path.
> .El
> +.It Fa tracker
> +The tracker used to track read owners of mountlist_lock
> +for priority propagation.
> .El
> .Sh RETURN VALUES
> A 0 value is returned on success.
> diff --git a/sys/cddl/compat/opensolaris/kern/opensolaris_lookup.c b/sys/cddl/compat/opensolaris/kern/opensolaris_lookup.c
> index 848007e..8e1c657b 100644
> --- a/sys/cddl/compat/opensolaris/kern/opensolaris_lookup.c
> +++ b/sys/cddl/compat/opensolaris/kern/opensolaris_lookup.c
> @@ -88,7 +88,7 @@ traverse(vnode_t **cvpp, int lktype)
> vfsp = vn_mountedvfs(cvp);
> if (vfsp == NULL)
> break;
> - error = vfs_busy(vfsp, 0);
> + error = vfs_busy(vfsp, 0, NULL);
> /*
> * tvp is NULL for *cvpp vnode, which we can't unlock.
> * At least some callers expect the reference to be
> diff --git a/sys/cddl/compat/opensolaris/kern/opensolaris_vfs.c b/sys/cddl/compat/opensolaris/kern/opensolaris_vfs.c
> index a2532f8..9476641 100644
> --- a/sys/cddl/compat/opensolaris/kern/opensolaris_vfs.c
> +++ b/sys/cddl/compat/opensolaris/kern/opensolaris_vfs.c
> @@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
> #include <sys/vfs.h>
> #include <sys/priv.h>
> #include <sys/libkern.h>
> +#include <sys/rmlock.h>
>
> MALLOC_DECLARE(M_MOUNT);
>
> @@ -222,9 +223,9 @@ mount_snapshot(kthread_t *td, vnode_t **vpp, const char *fstype, char *fspath,
>
> vp->v_mountedhere = mp;
> /* Put the new filesystem on the mount list. */
> - mtx_lock(&mountlist_mtx);
> + rm_wlock(&mountlist_lock);
> TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
> - mtx_unlock(&mountlist_mtx);
> + rm_wunlock(&mountlist_lock);
> vfs_event_signal(NULL, VQ_MOUNT, 0);
> if (VFS_ROOT(mp, LK_EXCLUSIVE, &mvp))
> panic("mount: lost mount");
> diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
> index a829b06..a684516 100644
> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
> @@ -142,6 +142,7 @@
> #include <sys/lock.h>
> #include <sys/malloc.h>
> #include <sys/mutex.h>
> +#include <sys/rmlock.h>
> #include <sys/proc.h>
> #include <sys/errno.h>
> #include <sys/uio.h>
> @@ -3014,15 +3015,16 @@ static vfs_t *
> zfs_get_vfs(const char *resource)
> {
> vfs_t *vfsp;
> + struct rm_priotracker tracker;
>
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH(vfsp, &mountlist, mnt_list) {
> if (strcmp(refstr_value(vfsp->vfs_resource), resource) == 0) {
> VFS_HOLD(vfsp);
> break;
> }
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> return (vfsp);
> }
>
> diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
> index 415db9e..55e11a1 100644
> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
> @@ -62,6 +62,7 @@
> #include <sys/dmu_objset.h>
> #include <sys/spa_boot.h>
> #include <sys/jail.h>
> +#include <sys/rmlock.h>
> #include "zfs_comutil.h"
>
> struct mtx zfs_debug_mtx;
> @@ -2532,12 +2533,13 @@ zfsvfs_update_fromname(const char *oldname, const char *newname)
> {
> char tmpbuf[MAXPATHLEN];
> struct mount *mp;
> + struct rm_priotracker tracker;
> char *fromname;
> size_t oldlen;
>
> oldlen = strlen(oldname);
>
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH(mp, &mountlist, mnt_list) {
> fromname = mp->mnt_stat.f_mntfromname;
> if (strcmp(fromname, oldname) == 0) {
> @@ -2554,6 +2556,6 @@ zfsvfs_update_fromname(const char *oldname, const char *newname)
> continue;
> }
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> }
> #endif
> diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
> index 8607646..2d5a538 100644
> --- a/sys/compat/linprocfs/linprocfs.c
> +++ b/sys/compat/linprocfs/linprocfs.c
> @@ -63,6 +63,7 @@ __FBSDID("$FreeBSD$");
> #include <sys/proc.h>
> #include <sys/ptrace.h>
> #include <sys/resourcevar.h>
> +#include <sys/rmlock.h>
> #include <sys/sbuf.h>
> #include <sys/sem.h>
> #include <sys/smp.h>
> @@ -327,6 +328,7 @@ linprocfs_domtab(PFS_FILL_ARGS)
> {
> struct nameidata nd;
> struct mount *mp;
> + struct rm_priotracker tracker;
> const char *lep;
> char *dlep, *flep, *mntto, *mntfrom, *fstype;
> size_t lep_len;
> @@ -344,7 +346,7 @@ linprocfs_domtab(PFS_FILL_ARGS)
> }
> lep_len = strlen(lep);
>
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> error = 0;
> TAILQ_FOREACH(mp, &mountlist, mnt_list) {
> /* determine device name */
> @@ -387,7 +389,7 @@ linprocfs_domtab(PFS_FILL_ARGS)
> /* a real Linux mtab will also show NFS options */
> sbuf_printf(sb, " 0 0\n");
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> free(flep, M_TEMP);
> return (error);
> }
> diff --git a/sys/fs/fuse/fuse_vnops.c b/sys/fs/fuse/fuse_vnops.c
> index 12b9778..b9827df 100644
> --- a/sys/fs/fuse/fuse_vnops.c
> +++ b/sys/fs/fuse/fuse_vnops.c
> @@ -902,11 +902,11 @@ calldaemon:
> */
> mp = dvp->v_mount;
> ltype = VOP_ISLOCKED(dvp);
> - err = vfs_busy(mp, MBF_NOWAIT);
> + err = vfs_busy(mp, MBF_NOWAIT, NULL);
> if (err != 0) {
> vfs_ref(mp);
> VOP_UNLOCK(dvp, 0);
> - err = vfs_busy(mp, 0);
> + err = vfs_busy(mp, 0, NULL);
> vn_lock(dvp, ltype | LK_RETRY);
> vfs_rel(mp);
> if (err)
> diff --git a/sys/fs/nfsclient/nfs_clstate.c b/sys/fs/nfsclient/nfs_clstate.c
> index 2600b80..8737003 100644
> --- a/sys/fs/nfsclient/nfs_clstate.c
> +++ b/sys/fs/nfsclient/nfs_clstate.c
> @@ -3621,7 +3621,7 @@ nfscl_getmnt(int minorvers, uint8_t *sessionid, u_int32_t cbident,
> mp = clp->nfsc_nmp->nm_mountp;
> vfs_ref(mp);
> NFSUNLOCKCLSTATE();
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vfs_rel(mp);
> if (error != 0)
> return (NULL);
> diff --git a/sys/fs/nfsclient/nfs_clvfsops.c b/sys/fs/nfsclient/nfs_clvfsops.c
> index 9758b4c..aa8f8bc 100644
> --- a/sys/fs/nfsclient/nfs_clvfsops.c
> +++ b/sys/fs/nfsclient/nfs_clvfsops.c
> @@ -287,7 +287,7 @@ nfs_statfs(struct mount *mp, struct statfs *sbp)
>
> td = curthread;
>
> - error = vfs_busy(mp, MBF_NOWAIT);
> + error = vfs_busy(mp, MBF_NOWAIT, NULL);
> if (error)
> return (error);
> error = ncl_nget(mp, nmp->nm_fh, nmp->nm_fhsize, &np, LK_EXCLUSIVE);
> diff --git a/sys/fs/nfsclient/nfs_clvnops.c b/sys/fs/nfsclient/nfs_clvnops.c
> index 513abf4..64a2eea 100644
> --- a/sys/fs/nfsclient/nfs_clvnops.c
> +++ b/sys/fs/nfsclient/nfs_clvnops.c
> @@ -1228,11 +1228,11 @@ nfs_lookup(struct vop_lookup_args *ap)
>
> if (flags & ISDOTDOT) {
> ltype = NFSVOPISLOCKED(dvp);
> - error = vfs_busy(mp, MBF_NOWAIT);
> + error = vfs_busy(mp, MBF_NOWAIT, NULL);
> if (error != 0) {
> vfs_ref(mp);
> NFSVOPUNLOCK(dvp, 0);
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> NFSVOPLOCK(dvp, ltype | LK_RETRY);
> vfs_rel(mp);
> if (error == 0 && (dvp->v_iflag & VI_DOOMED)) {
> diff --git a/sys/fs/nfsserver/nfs_nfsdport.c b/sys/fs/nfsserver/nfs_nfsdport.c
> index 0ea48cd..c8a80c8 100644
> --- a/sys/fs/nfsserver/nfs_nfsdport.c
> +++ b/sys/fs/nfsserver/nfs_nfsdport.c
> @@ -1985,7 +1985,7 @@ again:
> mp = vp->v_mount;
> vfs_ref(mp);
> NFSVOPUNLOCK(vp, 0);
> - nd->nd_repstat = vfs_busy(mp, 0);
> + nd->nd_repstat = vfs_busy(mp, 0, NULL);
> vfs_rel(mp);
> if (nd->nd_repstat != 0) {
> vrele(vp);
> @@ -2134,7 +2134,7 @@ again:
> nvp->v_type == VDIR &&
> nvp->v_mountedhere != NULL) {
> new_mp = nvp->v_mountedhere;
> - r = vfs_busy(new_mp, 0);
> + r = vfs_busy(new_mp, 0, NULL);
> vput(nvp);
> nvp = NULL;
> if (r == 0) {
> diff --git a/sys/fs/nfsserver/nfs_nfsdserv.c b/sys/fs/nfsserver/nfs_nfsdserv.c
> index e6e02d7..39f87c4 100644
> --- a/sys/fs/nfsserver/nfs_nfsdserv.c
> +++ b/sys/fs/nfsserver/nfs_nfsdserv.c
> @@ -271,7 +271,7 @@ nfsrvd_getattr(struct nfsrv_descript *nd, int isdgram,
> at_root = 0;
> }
> if (nd->nd_repstat == 0)
> - nd->nd_repstat = vfs_busy(mp, 0);
> + nd->nd_repstat = vfs_busy(mp, 0, NULL);
> vfs_rel(mp);
> if (nd->nd_repstat == 0) {
> (void)nfsvno_fillattr(nd, mp, vp, &nva,
> diff --git a/sys/fs/pseudofs/pseudofs_vnops.c b/sys/fs/pseudofs/pseudofs_vnops.c
> index f00b4b2..a0852ce 100644
> --- a/sys/fs/pseudofs/pseudofs_vnops.c
> +++ b/sys/fs/pseudofs/pseudofs_vnops.c
> @@ -392,7 +392,7 @@ pfs_vptocnp(struct vop_vptocnp_args *ap)
> pfs_unlock(pd);
>
> mp = vp->v_mount;
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> if (error)
> return (error);
>
> @@ -481,11 +481,11 @@ pfs_lookup(struct vop_cachedlookup_args *va)
> if (cnp->cn_flags & ISDOTDOT) {
> if (pd->pn_type == pfstype_root)
> PFS_RETURN (EIO);
> - error = vfs_busy(mp, MBF_NOWAIT);
> + error = vfs_busy(mp, MBF_NOWAIT, NULL);
> if (error != 0) {
> vfs_ref(mp);
> VOP_UNLOCK(vn, 0);
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vn_lock(vn, LK_EXCLUSIVE | LK_RETRY);
> vfs_rel(mp);
> if (error != 0)
> diff --git a/sys/fs/smbfs/smbfs_vnops.c b/sys/fs/smbfs/smbfs_vnops.c
> index 8ea1198..e0736fd 100644
> --- a/sys/fs/smbfs/smbfs_vnops.c
> +++ b/sys/fs/smbfs/smbfs_vnops.c
> @@ -1324,11 +1324,11 @@ smbfs_lookup(ap)
> }
> if (flags & ISDOTDOT) {
> mp = dvp->v_mount;
> - error = vfs_busy(mp, MBF_NOWAIT);
> + error = vfs_busy(mp, MBF_NOWAIT, NULL);
> if (error != 0) {
> vfs_ref(mp);
> VOP_UNLOCK(dvp, 0);
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY);
> vfs_rel(mp);
> if (error) {
> diff --git a/sys/fs/tmpfs/tmpfs_vnops.c b/sys/fs/tmpfs/tmpfs_vnops.c
> index 885f84c..a366170 100644
> --- a/sys/fs/tmpfs/tmpfs_vnops.c
> +++ b/sys/fs/tmpfs/tmpfs_vnops.c
> @@ -789,7 +789,7 @@ tmpfs_rename(struct vop_rename_args *v)
> if (fdvp != tdvp && fdvp != tvp) {
> if (vn_lock(fdvp, LK_EXCLUSIVE | LK_NOWAIT) != 0) {
> mp = tdvp->v_mount;
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> if (error != 0) {
> mp = NULL;
> goto out;
> diff --git a/sys/geom/journal/g_journal.c b/sys/geom/journal/g_journal.c
> index 9cc324c..3c2066e 100644
> --- a/sys/geom/journal/g_journal.c
> +++ b/sys/geom/journal/g_journal.c
> @@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
> #include <sys/limits.h>
> #include <sys/lock.h>
> #include <sys/mutex.h>
> +#include <sys/rmlock.h>
> #include <sys/bio.h>
> #include <sys/sysctl.h>
> #include <sys/malloc.h>
> @@ -2867,6 +2868,7 @@ g_journal_do_switch(struct g_class *classp)
> const struct g_journal_desc *desc;
> struct g_geom *gp;
> struct mount *mp;
> + struct rm_priotracker tracker;
> struct bintime bt;
> char *mountpoint;
> int error, save;
> @@ -2888,7 +2890,7 @@ g_journal_do_switch(struct g_class *classp)
> g_topology_unlock();
> PICKUP_GIANT();
>
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH(mp, &mountlist, mnt_list) {
> if (mp->mnt_gjprovider == NULL)
> continue;
> @@ -2897,9 +2899,10 @@ g_journal_do_switch(struct g_class *classp)
> desc = g_journal_find_desc(mp->mnt_stat.f_fstypename);
> if (desc == NULL)
> continue;
> - if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK))
> + if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK, &tracker))
> continue;
> - /* mtx_unlock(&mountlist_mtx) was done inside vfs_busy() */
> + /* rm_runlock(&mountlist_lock, &tracker) was done inside
> + * vfs_busy() */
>
> DROP_GIANT();
> g_topology_lock();
> @@ -2977,10 +2980,10 @@ g_journal_do_switch(struct g_class *classp)
>
> vfs_write_resume(mp, 0);
> next:
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> vfs_unbusy(mp);
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
>
> sc = NULL;
> for (;;) {
> diff --git a/sys/kern/vfs_extattr.c b/sys/kern/vfs_extattr.c
> index 24935ce..a82eddaf 100644
> --- a/sys/kern/vfs_extattr.c
> +++ b/sys/kern/vfs_extattr.c
> @@ -104,7 +104,7 @@ sys_extattrctl(td, uap)
> if (error)
> goto out;
> mp = nd.ni_vp->v_mount;
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> if (error) {
> NDFREE(&nd, 0);
> mp = NULL;
> diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
> index f2ffab2..610aa5f 100644
> --- a/sys/kern/vfs_lookup.c
> +++ b/sys/kern/vfs_lookup.c
> @@ -779,7 +779,7 @@ unionlookup:
> */
> while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
> (cnp->cn_flags & NOCROSSMOUNT) == 0) {
> - if (vfs_busy(mp, 0))
> + if (vfs_busy(mp, 0, NULL))
> continue;
> vput(dp);
> if (dp != ndp->ni_dvp)
> diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
> index 09fa7ed..636a55f 100644
> --- a/sys/kern/vfs_mount.c
> +++ b/sys/kern/vfs_mount.c
> @@ -51,6 +51,7 @@ __FBSDID("$FreeBSD$");
> #include <sys/proc.h>
> #include <sys/filedesc.h>
> #include <sys/reboot.h>
> +#include <sys/rmlock.h>
> #include <sys/sbuf.h>
> #include <sys/syscallsubr.h>
> #include <sys/sysproto.h>
> @@ -85,8 +86,8 @@ static uma_zone_t mount_zone;
> struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);
>
> /* For any iteration/modification of mountlist */
> -struct mtx mountlist_mtx;
> -MTX_SYSINIT(mountlist, &mountlist_mtx, "mountlist", MTX_DEF);
> +struct rmlock mountlist_lock;
> +RM_SYSINIT(mountlist, &mountlist_lock, "mountlist");
>
> /*
> * Global opts, taken by all filesystems
> @@ -462,7 +463,7 @@ vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp, const char *fspath,
> TAILQ_INIT(&mp->mnt_activevnodelist);
> mp->mnt_activevnodelistsize = 0;
> mp->mnt_ref = 0;
> - (void) vfs_busy(mp, MBF_NOWAIT);
> + (void) vfs_busy(mp, MBF_NOWAIT, NULL);
> atomic_add_acq_int(&vfsp->vfc_refcount, 1);
> mp->mnt_op = vfsp->vfc_vfsops;
> mp->mnt_vfc = vfsp;
> @@ -852,9 +853,9 @@ vfs_domount_first(
> VI_UNLOCK(vp);
> vp->v_mountedhere = mp;
> /* Place the new filesystem at the end of the mount list. */
> - mtx_lock(&mountlist_mtx);
> + rm_wlock(&mountlist_lock);
> TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
> - mtx_unlock(&mountlist_mtx);
> + rm_wunlock(&mountlist_lock);
> vfs_event_signal(NULL, VQ_MOUNT, 0);
> if (VFS_ROOT(mp, LK_EXCLUSIVE, &newdp))
> panic("mount: lost mount");
> @@ -918,7 +919,7 @@ vfs_domount_update(
> vput(vp);
> return (error);
> }
> - if (vfs_busy(mp, MBF_NOWAIT)) {
> + if (vfs_busy(mp, MBF_NOWAIT, NULL)) {
> vput(vp);
> return (EBUSY);
> }
> @@ -1137,6 +1138,7 @@ sys_unmount(td, uap)
> {
> struct nameidata nd;
> struct mount *mp;
> + struct rm_priotracker tracker;
> char *pathbuf;
> int error, id0, id1;
>
> @@ -1161,13 +1163,13 @@ sys_unmount(td, uap)
> return (EINVAL);
> }
>
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH_REVERSE(mp, &mountlist, mntlist, mnt_list) {
> if (mp->mnt_stat.f_fsid.val[0] == id0 &&
> mp->mnt_stat.f_fsid.val[1] == id1)
> break;
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> } else {
> /*
> * Try to find global path for path argument.
> @@ -1181,12 +1183,12 @@ sys_unmount(td, uap)
> if (error == 0 || error == ENODEV)
> vput(nd.ni_vp);
> }
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH_REVERSE(mp, &mountlist, mntlist, mnt_list) {
> if (strcmp(mp->mnt_stat.f_mntonname, pathbuf) == 0)
> break;
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> }
> free(pathbuf, M_TEMP);
> if (mp == NULL) {
> @@ -1353,9 +1355,9 @@ dounmount(mp, flags, td)
> VOP_UNLOCK(coveredvp, 0);
> return (error);
> }
> - mtx_lock(&mountlist_mtx);
> + rm_wlock(&mountlist_lock);
> TAILQ_REMOVE(&mountlist, mp, mnt_list);
> - mtx_unlock(&mountlist_mtx);
> + rm_wunlock(&mountlist_lock);
> EVENTHANDLER_INVOKE(vfs_unmounted, mp, td);
> if (coveredvp != NULL) {
> coveredvp->v_mountedhere = NULL;
> diff --git a/sys/kern/vfs_mountroot.c b/sys/kern/vfs_mountroot.c
> index a050099..ef3e9c9 100644
> --- a/sys/kern/vfs_mountroot.c
> +++ b/sys/kern/vfs_mountroot.c
> @@ -55,6 +55,7 @@ __FBSDID("$FreeBSD$");
> #include <sys/proc.h>
> #include <sys/filedesc.h>
> #include <sys/reboot.h>
> +#include <sys/rmlock.h>
> #include <sys/sbuf.h>
> #include <sys/stat.h>
> #include <sys/syscallsubr.h>
> @@ -231,9 +232,9 @@ vfs_mountroot_devfs(struct thread *td, struct mount **mpp)
> TAILQ_INIT(opts);
> mp->mnt_opt = opts;
>
> - mtx_lock(&mountlist_mtx);
> + rm_wlock(&mountlist_lock);
> TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
> - mtx_unlock(&mountlist_mtx);
> + rm_wunlock(&mountlist_lock);
>
> *mpp = mp;
> set_rootvnode();
> @@ -257,7 +258,7 @@ vfs_mountroot_shuffle(struct thread *td, struct mount *mpdevfs)
> mpnroot = TAILQ_NEXT(mpdevfs, mnt_list);
>
> /* Shuffle the mountlist. */
> - mtx_lock(&mountlist_mtx);
> + rm_wlock(&mountlist_lock);
> mporoot = TAILQ_FIRST(&mountlist);
> TAILQ_REMOVE(&mountlist, mpdevfs, mnt_list);
> if (mporoot != mpdevfs) {
> @@ -265,7 +266,7 @@ vfs_mountroot_shuffle(struct thread *td, struct mount *mpdevfs)
> TAILQ_INSERT_HEAD(&mountlist, mpnroot, mnt_list);
> }
> TAILQ_INSERT_TAIL(&mountlist, mpdevfs, mnt_list);
> - mtx_unlock(&mountlist_mtx);
> + rm_wunlock(&mountlist_lock);
>
> cache_purgevfs(mporoot);
> if (mporoot != mpdevfs)
> @@ -933,6 +934,7 @@ void
> vfs_mountroot(void)
> {
> struct mount *mp;
> + struct rm_priotracker tracker;
> struct sbuf *sb;
> struct thread *td;
> time_t timebase;
> @@ -968,14 +970,14 @@ vfs_mountroot(void)
> * timestamps we encounter.
> */
> timebase = 0;
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> mp = TAILQ_FIRST(&mountlist);
> while (mp != NULL) {
> if (mp->mnt_time > timebase)
> timebase = mp->mnt_time;
> mp = TAILQ_NEXT(mp, mnt_list);
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> inittodr(timebase);
>
> /* Keep prison0's root in sync with the global rootvnode. */
> diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
> index fda80c9..3733178 100644
> --- a/sys/kern/vfs_subr.c
> +++ b/sys/kern/vfs_subr.c
> @@ -68,6 +68,7 @@ __FBSDID("$FreeBSD$");
> #include <sys/pctrie.h>
> #include <sys/priv.h>
> #include <sys/reboot.h>
> +#include <sys/rmlock.h>
> #include <sys/rwlock.h>
> #include <sys/sched.h>
> #include <sys/sleepqueue.h>
> @@ -375,7 +376,7 @@ SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vntblinit, NULL);
>
> /*
> * Mark a mount point as busy. Used to synchronize access and to delay
> - * unmounting. Eventually, mountlist_mtx is not released on failure.
> + * unmounting. Eventually, mountlist_lock is not released on failure.
> *
> * vfs_busy() is a custom lock, it can block the caller.
> * vfs_busy() only sleeps if the unmount is active on the mount point.
> @@ -410,7 +411,7 @@ SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vntblinit, NULL);
> * dounmount() locks B while F is drained.
> */
> int
> -vfs_busy(struct mount *mp, int flags)
> +vfs_busy(struct mount *mp, int flags, struct rm_priotracker *tracker)
> {
>
> MPASS((flags & ~MBF_MASK) == 0);
> @@ -439,15 +440,15 @@ vfs_busy(struct mount *mp, int flags)
> return (ENOENT);
> }
> if (flags & MBF_MNTLSTLOCK)
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, tracker);
> mp->mnt_kern_flag |= MNTK_MWAIT;
> msleep(mp, MNT_MTX(mp), PVFS | PDROP, "vfs_busy", 0);
> if (flags & MBF_MNTLSTLOCK)
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, tracker);
> MNT_ILOCK(mp);
> }
> if (flags & MBF_MNTLSTLOCK)
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, tracker);
> mp->mnt_lockref++;
> MNT_IUNLOCK(mp);
> return (0);
> @@ -481,18 +482,19 @@ struct mount *
> vfs_getvfs(fsid_t *fsid)
> {
> struct mount *mp;
> + struct rm_priotracker tracker;
>
> CTR2(KTR_VFS, "%s: fsid %p", __func__, fsid);
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH(mp, &mountlist, mnt_list) {
> if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
> mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
> vfs_ref(mp);
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> return (mp);
> }
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> CTR2(KTR_VFS, "%s: lookup failed for %p id", __func__, fsid);
> return ((struct mount *) 0);
> }
> @@ -501,7 +503,7 @@ vfs_getvfs(fsid_t *fsid)
> * Lookup a mount point by filesystem identifier, busying it before
> * returning.
> *
> - * To avoid congestion on mountlist_mtx, implement simple direct-mapped
> + * To avoid congestion on mountlist_lock, implement simple direct-mapped
> * cache for popular filesystem identifiers. The cache is lockess, using
> * the fact that struct mount's are never freed. In worst case we may
> * get pointer to unmounted or even different filesystem, so we have to
> @@ -514,6 +516,7 @@ vfs_busyfs(fsid_t *fsid)
> typedef struct mount * volatile vmp_t;
> static vmp_t cache[FSID_CACHE_SIZE];
> struct mount *mp;
> + struct rm_priotracker tracker;
> int error;
> uint32_t hash;
>
> @@ -525,7 +528,7 @@ vfs_busyfs(fsid_t *fsid)
> mp->mnt_stat.f_fsid.val[0] != fsid->val[0] ||
> mp->mnt_stat.f_fsid.val[1] != fsid->val[1])
> goto slow;
> - if (vfs_busy(mp, 0) != 0) {
> + if (vfs_busy(mp, 0, NULL) != 0) {
> cache[hash] = NULL;
> goto slow;
> }
> @@ -536,14 +539,14 @@ vfs_busyfs(fsid_t *fsid)
> vfs_unbusy(mp);
>
> slow:
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH(mp, &mountlist, mnt_list) {
> if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
> mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
> - error = vfs_busy(mp, MBF_MNTLSTLOCK);
> + error = vfs_busy(mp, MBF_MNTLSTLOCK, &tracker);
> if (error) {
> cache[hash] = NULL;
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> return (NULL);
> }
> cache[hash] = mp;
> @@ -551,7 +554,7 @@ slow:
> }
> }
> CTR2(KTR_VFS, "%s: lookup failed for %p id", __func__, fsid);
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> return ((struct mount *) 0);
> }
>
> @@ -891,6 +894,7 @@ vnlru_proc(void)
> struct mount *mp, *nmp;
> int done;
> struct proc *p = vnlruproc;
> + struct rm_priotracker tracker;
>
> EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, p,
> SHUTDOWN_PRI_FIRST);
> @@ -909,18 +913,18 @@ vnlru_proc(void)
> }
> mtx_unlock(&vnode_free_list_mtx);
> done = 0;
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
> - if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK)) {
> + if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK, &tracker)) {
> nmp = TAILQ_NEXT(mp, mnt_list);
> continue;
> }
> done += vlrureclaim(mp);
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> nmp = TAILQ_NEXT(mp, mnt_list);
> vfs_unbusy(mp);
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> if (done == 0) {
> #if 0
> /* These messages are temporary debugging aids */
> @@ -3397,6 +3401,7 @@ sysctl_vnode(SYSCTL_HANDLER_ARGS)
> struct xvnode *xvn;
> struct mount *mp;
> struct vnode *vp;
> + struct rm_priotracker tracker;
> int error, len, n;
>
> /*
> @@ -3413,9 +3418,9 @@ sysctl_vnode(SYSCTL_HANDLER_ARGS)
> return (error);
> xvn = malloc(len, M_TEMP, M_ZERO | M_WAITOK);
> n = 0;
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH(mp, &mountlist, mnt_list) {
> - if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK))
> + if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK, &tracker))
> continue;
> MNT_ILOCK(mp);
> TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
> @@ -3465,12 +3470,12 @@ sysctl_vnode(SYSCTL_HANDLER_ARGS)
> ++n;
> }
> MNT_IUNLOCK(mp);
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> vfs_unbusy(mp);
> if (n == len)
> break;
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
>
> error = SYSCTL_OUT(req, xvn, n * sizeof *xvn);
> free(xvn, M_TEMP);
> @@ -3760,7 +3765,7 @@ sync_fsync(struct vop_fsync_args *ap)
> * Walk the list of vnodes pushing all that are dirty and
> * not already on the sync list.
> */
> - if (vfs_busy(mp, MBF_NOWAIT) != 0)
> + if (vfs_busy(mp, MBF_NOWAIT, NULL) != 0)
> return (0);
> if (vn_start_write(NULL, &mp, V_NOWAIT) != 0) {
> vfs_unbusy(mp);
> diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
> index 14be379..0d3ae31 100644
> --- a/sys/kern/vfs_syscalls.c
> +++ b/sys/kern/vfs_syscalls.c
> @@ -60,6 +60,7 @@ __FBSDID("$FreeBSD$");
> #include <sys/filio.h>
> #include <sys/limits.h>
> #include <sys/linker.h>
> +#include <sys/rmlock.h>
> #include <sys/rwlock.h>
> #include <sys/sdt.h>
> #include <sys/stat.h>
> @@ -129,11 +130,12 @@ sys_sync(td, uap)
> struct sync_args *uap;
> {
> struct mount *mp, *nmp;
> + struct rm_priotracker tracker;
> int save;
>
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
> - if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK)) {
> + if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK, &tracker)) {
> nmp = TAILQ_NEXT(mp, mnt_list);
> continue;
> }
> @@ -145,11 +147,11 @@ sys_sync(td, uap)
> curthread_pflags_restore(save);
> vn_finished_write(mp);
> }
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> nmp = TAILQ_NEXT(mp, mnt_list);
> vfs_unbusy(mp);
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> return (0);
> }
>
> @@ -190,7 +192,7 @@ sys_quotactl(td, uap)
> mp = nd.ni_vp->v_mount;
> vfs_ref(mp);
> vput(nd.ni_vp);
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vfs_rel(mp);
> if (error != 0)
> return (error);
> @@ -297,7 +299,7 @@ kern_statfs(struct thread *td, char *path, enum uio_seg pathseg,
> vfs_ref(mp);
> NDFREE(&nd, NDF_ONLY_PNBUF);
> vput(nd.ni_vp);
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vfs_rel(mp);
> if (error != 0)
> return (error);
> @@ -383,7 +385,7 @@ kern_fstatfs(struct thread *td, int fd, struct statfs *buf)
> error = EBADF;
> goto out;
> }
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vfs_rel(mp);
> if (error != 0)
> return (error);
> @@ -449,6 +451,7 @@ kern_getfsstat(struct thread *td, struct statfs **buf, size_t bufsize,
> enum uio_seg bufseg, int flags)
> {
> struct mount *mp, *nmp;
> + struct rm_priotracker tracker;
> struct statfs *sfsp, *sp, sb;
> size_t count, maxcount;
> int error;
> @@ -460,18 +463,18 @@ kern_getfsstat(struct thread *td, struct statfs **buf, size_t bufsize,
> sfsp = *buf;
> else /* if (bufseg == UIO_SYSSPACE) */ {
> count = 0;
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> TAILQ_FOREACH(mp, &mountlist, mnt_list) {
> count++;
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> if (maxcount > count)
> maxcount = count;
> sfsp = *buf = malloc(maxcount * sizeof(struct statfs), M_TEMP,
> M_WAITOK);
> }
> count = 0;
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
> if (prison_canseemount(td->td_ucred, mp) != 0) {
> nmp = TAILQ_NEXT(mp, mnt_list);
> @@ -483,7 +486,7 @@ kern_getfsstat(struct thread *td, struct statfs **buf, size_t bufsize,
> continue;
> }
> #endif
> - if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK)) {
> + if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK, &tracker)) {
> nmp = TAILQ_NEXT(mp, mnt_list);
> continue;
> }
> @@ -504,7 +507,7 @@ kern_getfsstat(struct thread *td, struct statfs **buf, size_t bufsize,
> if (((flags & (MNT_LAZY|MNT_NOWAIT)) == 0 ||
> (flags & MNT_WAIT)) &&
> (error = VFS_STATFS(mp, sp))) {
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> nmp = TAILQ_NEXT(mp, mnt_list);
> vfs_unbusy(mp);
> continue;
> @@ -527,11 +530,11 @@ kern_getfsstat(struct thread *td, struct statfs **buf, size_t bufsize,
> sfsp++;
> }
> count++;
> - mtx_lock(&mountlist_mtx);
> + rm_rlock(&mountlist_lock, &tracker);
> nmp = TAILQ_NEXT(mp, mnt_list);
> vfs_unbusy(mp);
> }
> - mtx_unlock(&mountlist_mtx);
> + rm_runlock(&mountlist_lock, &tracker);
> if (sfsp && count > maxcount)
> td->td_retval[0] = maxcount;
> else
> @@ -741,7 +744,7 @@ sys_fchdir(td, uap)
> AUDIT_ARG_VNODE1(vp);
> error = change_dir(vp, td);
> while (!error && (mp = vp->v_mountedhere) != NULL) {
> - if (vfs_busy(mp, 0))
> + if (vfs_busy(mp, 0, NULL))
> continue;
> error = VFS_ROOT(mp, LK_SHARED, &tdp);
> vfs_unbusy(mp);
> diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
> index ed4ad4d..8d38305 100644
> --- a/sys/kern/vfs_vnops.c
> +++ b/sys/kern/vfs_vnops.c
> @@ -2059,11 +2059,11 @@ vn_vget_ino_gen(struct vnode *vp, vn_get_ino_t alloc, void *alloc_arg,
> ltype = VOP_ISLOCKED(vp);
> KASSERT(ltype == LK_EXCLUSIVE || ltype == LK_SHARED,
> ("vn_vget_ino: vp not locked"));
> - error = vfs_busy(mp, MBF_NOWAIT);
> + error = vfs_busy(mp, MBF_NOWAIT, NULL);
> if (error != 0) {
> vfs_ref(mp);
> VOP_UNLOCK(vp, 0);
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vn_lock(vp, ltype | LK_RETRY);
> vfs_rel(mp);
> if (error != 0)
> diff --git a/sys/sys/mount.h b/sys/sys/mount.h
> index 6fb2d08..6c47d7f 100644
> --- a/sys/sys/mount.h
> +++ b/sys/sys/mount.h
> @@ -38,7 +38,9 @@
> #ifdef _KERNEL
> #include <sys/lock.h>
> #include <sys/lockmgr.h>
> +#include <sys/pcpu.h>
> #include <sys/_mutex.h>
> +#include <sys/_rmlock.h>
> #include <sys/_sx.h>
> #endif
>
> @@ -147,7 +149,7 @@ struct vfsopt {
> * put on a doubly linked list.
> *
> * Lock reference:
> - * m - mountlist_mtx
> + * m - mountlist_lock
> * i - interlock
> * v - vnode freelist mutex
> *
> @@ -864,7 +866,7 @@ int vfs_setopts(struct vfsoptlist *opts, const char *name,
> int vfs_setpublicfs /* set publicly exported fs */
> (struct mount *, struct netexport *, struct export_args *);
> void vfs_msync(struct mount *, int);
> -int vfs_busy(struct mount *, int);
> +int vfs_busy(struct mount *, int, struct rm_priotracker *);
> int vfs_export /* process mount export info */
> (struct mount *, struct export_args *);
> void vfs_allocate_syncvnode(struct mount *);
> @@ -890,7 +892,7 @@ int vfs_suser(struct mount *, struct thread *);
> void vfs_unbusy(struct mount *);
> void vfs_unmountall(void);
> extern TAILQ_HEAD(mntlist, mount) mountlist; /* mounted filesystem list */
> -extern struct mtx mountlist_mtx;
> +extern struct rmlock mountlist_lock;
> extern struct nfs_public nfs_pub;
> extern struct sx vfsconf_sx;
> #define vfsconf_lock() sx_xlock(&vfsconf_sx)
> diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
> index 700854e..8545df0 100644
> --- a/sys/ufs/ffs/ffs_softdep.c
> +++ b/sys/ufs/ffs/ffs_softdep.c
> @@ -12274,11 +12274,11 @@ restart:
> FREE_LOCK(ump);
> if (ffs_vgetf(mp, parentino, LK_NOWAIT | LK_EXCLUSIVE, &pvp,
> FFSV_FORCEINSMQ)) {
> - error = vfs_busy(mp, MBF_NOWAIT);
> + error = vfs_busy(mp, MBF_NOWAIT, NULL);
> if (error != 0) {
> vfs_ref(mp);
> VOP_UNLOCK(vp, 0);
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
> vfs_rel(mp);
> if (error != 0)
> @@ -13427,7 +13427,7 @@ clear_remove(mp)
> /*
> * Let unmount clear deps
> */
> - error = vfs_busy(mp, MBF_NOWAIT);
> + error = vfs_busy(mp, MBF_NOWAIT, NULL);
> if (error != 0)
> goto finish_write;
> error = ffs_vgetf(mp, ino, LK_EXCLUSIVE, &vp,
> @@ -13503,7 +13503,7 @@ clear_inodedeps(mp)
> if (vn_start_write(NULL, &mp, V_NOWAIT) != 0)
> continue;
> FREE_LOCK(ump);
> - error = vfs_busy(mp, MBF_NOWAIT); /* Let unmount clear deps */
> + error = vfs_busy(mp, MBF_NOWAIT, NULL); /* Let unmount clear deps */
> if (error != 0) {
> vn_finished_write(mp);
> ACQUIRE_LOCK(ump);
> diff --git a/sys/ufs/ffs/ffs_suspend.c b/sys/ufs/ffs/ffs_suspend.c
> index b50fadc..6513a21 100644
> --- a/sys/ufs/ffs/ffs_suspend.c
> +++ b/sys/ufs/ffs/ffs_suspend.c
> @@ -286,7 +286,7 @@ ffs_susp_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
> error = ENOENT;
> break;
> }
> - error = vfs_busy(mp, 0);
> + error = vfs_busy(mp, 0, NULL);
> vfs_rel(mp);
> if (error != 0)
> break;
> diff --git a/sys/ufs/ufs/ufs_quota.c b/sys/ufs/ufs/ufs_quota.c
> index 4fbb8a1..3d17622 100644
> --- a/sys/ufs/ufs/ufs_quota.c
> +++ b/sys/ufs/ufs/ufs_quota.c
> @@ -519,7 +519,7 @@ quotaon(struct thread *td, struct mount *mp, int type, void *fname)
> }
> NDFREE(&nd, NDF_ONLY_PNBUF);
> vp = nd.ni_vp;
> - error = vfs_busy(mp, MBF_NOWAIT);
> + error = vfs_busy(mp, MBF_NOWAIT, NULL);
> vfs_rel(mp);
> if (error == 0) {
> if (vp->v_type != VREG) {
> --
> 2.1.2
>
> > The rmlock primitive does exactly this optimization. See the manpage
> > for the API (it's mostly very similar to the rwlock API):
> > https://www.freebsd.org/cgi/man.cgi?query=rmlock&apropos=0&sektion=0&manpath=FreeBSD+10.1-RELEASE&arch=default&format=html
> >
> >
> > > void zfs_mountlist_wlock(void);
> > > void zfs_mountlist_wunlock(void);
> > > void zfs_mountlist_rlock(void);
> > > void zfs_mountlist_runlock(void);
> >
> > Why not:
> >
> > #define zfs_mountlist_wlock() _zfs_mountlist_wlock(__FILE__, __LINE__)
> > void _zfs_mountlist_wlock(const char *file, int line);
> >
> > /* etc, etc */
> >
> > (This may be moot if we switch to an rmlock though)
>
> Tiwei Bie
>
--
Mateusz Guzik <mjguzik gmail.com>
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