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-rw-r--r--sys/kern/vfs_mount.c34
-rw-r--r--sys/kern/vfs_subr.c14
-rw-r--r--sys/sys/mount.h28
3 files changed, 61 insertions, 15 deletions
diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index 2015a43..0e7aa86 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -405,6 +405,24 @@ nmount(td, uap)
* Various utility functions
*/
+void
+vfs_ref(struct mount *mp)
+{
+
+ MNT_ILOCK(mp);
+ MNT_REF(mp);
+ MNT_IUNLOCK(mp);
+}
+
+void
+vfs_rel(struct mount *mp)
+{
+
+ MNT_ILOCK(mp);
+ MNT_REL(mp);
+ MNT_IUNLOCK(mp);
+}
+
/*
* Allocate and initialize the mount point struct.
*/
@@ -420,9 +438,10 @@ vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp,
mtx_init(&mp->mnt_mtx, "struct mount mtx", NULL, MTX_DEF);
lockinit(&mp->mnt_lock, PVFS, "vfslock", 0, 0);
(void) vfs_busy(mp, LK_NOWAIT, 0, td);
+ mp->mnt_ref = 0;
mp->mnt_op = vfsp->vfc_vfsops;
mp->mnt_vfc = vfsp;
- vfsp->vfc_refcount++;
+ vfsp->vfc_refcount++; /* XXX Unlocked */
mp->mnt_stat.f_type = vfsp->vfc_typenum;
mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK;
strlcpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
@@ -445,8 +464,19 @@ vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp,
static void
vfs_mount_destroy(struct mount *mp, struct thread *td)
{
+ int i;
MNT_ILOCK(mp);
+ for (i = 0; mp->mnt_ref && i < 3; i++)
+ msleep(mp, MNT_MTX(mp), PVFS, "mntref", hz);
+ /*
+ * This will always cause a 3 second delay in rebooting due to
+ * refs on the root mountpoint that never go away. Most of these
+ * are held by init which never exits.
+ */
+ if (i == 3 && (!rebooting || bootverbose))
+ printf("Mount point %s had %d dangling refs\n",
+ mp->mnt_stat.f_mntonname, mp->mnt_ref);
if (mp->mnt_holdcnt != 0) {
printf("Waiting for mount point to be unheld\n");
while (mp->mnt_holdcnt != 0) {
@@ -1305,8 +1335,8 @@ devfs_fixup(struct thread *td)
TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
mtx_unlock(&mountlist_mtx);
VOP_UNLOCK(vp, 0, td);
- vfs_unbusy(mp, td);
vput(dvp);
+ vfs_unbusy(mp, td);
/* Unlink the no longer needed /dev/dev -> / symlink */
kern_unlink(td, "/dev/dev", UIO_SYSSPACE);
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index ca85214..5017c72 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -785,6 +785,8 @@ vdestroy(struct vnode *vp)
mtx_destroy(&vp->v_pollinfo->vpi_lock);
uma_zfree(vnodepoll_zone, vp->v_pollinfo);
}
+ if (vp->v_mount)
+ vfs_rel(vp->v_mount);
#ifdef INVARIANTS
/* XXX Elsewhere we can detect an already freed vnode via NULL v_op. */
vp->v_op = NULL;
@@ -918,7 +920,6 @@ getnewvnode(const char *tag, struct mount *mp, struct vop_vector *vops,
else if (mp == NULL)
printf("NULL mp in getnewvnode()\n");
#endif
- delmntque(vp);
if (mp != NULL) {
insmntque(vp, mp);
bo->bo_bsize = mp->mnt_stat.f_iosize;
@@ -939,15 +940,15 @@ delmntque(struct vnode *vp)
{
struct mount *mp;
- if (vp->v_mount == NULL)
- return;
mp = vp->v_mount;
+ if (mp == NULL)
+ return;
MNT_ILOCK(mp);
- vp->v_mount = NULL;
VNASSERT(mp->mnt_nvnodelistsize > 0, vp,
("bad mount point vnode list size"));
TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
mp->mnt_nvnodelistsize--;
+ /* mnt ref is released in vdestroy. */
MNT_IUNLOCK(mp);
}
@@ -960,12 +961,13 @@ insmntque(struct vnode *vp, struct mount *mp)
vp->v_mount = mp;
VNASSERT(mp != NULL, vp, ("Don't call insmntque(foo, NULL)"));
- MNT_ILOCK(vp->v_mount);
+ MNT_ILOCK(mp);
+ MNT_REF(mp);
TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
VNASSERT(mp->mnt_nvnodelistsize >= 0, vp,
("neg mount point vnode list size"));
mp->mnt_nvnodelistsize++;
- MNT_IUNLOCK(vp->v_mount);
+ MNT_IUNLOCK(mp);
}
/*
diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index ccec2fc..6c741cb 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -134,21 +134,30 @@ struct vfsopt;
* array of operations and an instance record. The filesystems are
* put on a doubly linked list.
*
+ * Lock reference:
+ * m - mountlist_mtx
+ * i - interlock
+ * l - mnt_lock
+ *
+ * Unmarked fields are considered stable as long as a ref is held.
+ *
*/
struct mount {
- TAILQ_ENTRY(mount) mnt_list; /* mount list */
+ TAILQ_ENTRY(mount) mnt_list; /* (m) mount list */
struct vfsops *mnt_op; /* operations on fs */
struct vfsconf *mnt_vfc; /* configuration info */
struct vnode *mnt_vnodecovered; /* vnode we mounted on */
struct vnode *mnt_syncer; /* syncer vnode */
- struct vnodelst mnt_nvnodelist; /* list of vnodes this mount */
struct lock mnt_lock; /* mount structure lock */
struct mtx mnt_mtx; /* mount structure interlock */
- int mnt_writeopcount; /* write syscalls in progress */
+ int mnt_ref; /* (i) Reference count */
+ struct vnodelst mnt_nvnodelist; /* (i) list of vnodes */
+ int mnt_nvnodelistsize; /* (i) # of vnodes */
+ int mnt_writeopcount; /* (i) write syscalls pending */
+ int mnt_kern_flag; /* (i) kernel only flags */
u_int mnt_flag; /* flags shared with user */
struct vfsoptlist *mnt_opt; /* current mount options */
struct vfsoptlist *mnt_optnew; /* new options passed to fs */
- int mnt_kern_flag; /* kernel only flags */
int mnt_maxsymlinklen; /* max size of short symlink */
struct statfs mnt_stat; /* cache of filesystem stats */
struct ucred *mnt_cred; /* credentials of mounter */
@@ -158,7 +167,6 @@ struct mount {
struct netexport *mnt_export; /* export list */
struct label *mnt_mntlabel; /* MAC label for the mount */
struct label *mnt_fslabel; /* MAC label for the fs */
- int mnt_nvnodelistsize; /* # of vnodes on this mount */
u_int mnt_hashseed; /* Random seed for vfs_hash */
int mnt_markercnt; /* marker vnodes in use */
int mnt_holdcnt; /* hold count */
@@ -186,6 +194,12 @@ void __mnt_vnode_markerfree(struct vnode **mvp, struct mount *mp);
#define MNT_ILOCK(mp) mtx_lock(&(mp)->mnt_mtx)
#define MNT_IUNLOCK(mp) mtx_unlock(&(mp)->mnt_mtx)
#define MNT_MTX(mp) (&(mp)->mnt_mtx)
+#define MNT_REF(mp) (mp)->mnt_ref++
+#define MNT_REL(mp) do { \
+ (mp)->mnt_ref--; \
+ if ((mp)->mnt_ref == 0) \
+ wakeup((mp)); \
+} while (0)
#endif /* _KERNEL */
@@ -629,9 +643,7 @@ int vfs_filteropt(struct vfsoptlist *, const char **legal);
int vfs_scanopt(struct vfsoptlist *opts, const char *name, const char *fmt, ...);
int vfs_setpublicfs /* set publicly exported fs */
(struct mount *, struct netexport *, struct export_args *);
-int vfs_lock(struct mount *); /* lock a vfs */
void vfs_msync(struct mount *, int);
-void vfs_unlock(struct mount *); /* unlock a vfs */
int vfs_busy(struct mount *, int, struct mtx *, struct thread *);
int vfs_export /* process mount export info */
(struct mount *, struct export_args *);
@@ -643,6 +655,8 @@ int vfs_modevent(module_t, int, void *);
void vfs_mount_error(struct mount *, const char *, ...);
void vfs_mountroot(void); /* mount our root filesystem */
void vfs_mountedfrom(struct mount *, const char *from);
+void vfs_ref(struct mount *);
+void vfs_rel(struct mount *);
int vfs_suser(struct mount *, struct thread *);
void vfs_unbusy(struct mount *, struct thread *);
void vfs_unmountall(void);
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