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diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -933,7 +933,6 @@
int lkflags_save;
int ni_dvp_unlocked;
int crosslkflags;
- bool crosslock;
/*
* Setup: break out flag bits into variables.
@@ -1301,39 +1300,24 @@
mp = dp->v_mountedhere;
KASSERT(mp != NULL,
("%s: NULL mountpoint for VIRF_MOUNTPOINT vnode", __func__));
- crosslock = (dp->v_vflag & VV_CROSSLOCK) != 0;
crosslkflags = compute_cn_lkflags(mp, cnp->cn_lkflags,
cnp->cn_flags);
- if (__predict_false(crosslock)) {
- /*
- * We are going to be holding the vnode lock, which
- * in this case is shared by the root vnode of the
- * filesystem mounted at mp, across the call to
- * VFS_ROOT(). Make the situation clear to the
- * filesystem by passing LK_CANRECURSE if the
- * lock is held exclusive, or by clearinng
- * LK_NODDLKTREAT to allow recursion on the shared
- * lock in the presence of an exclusive waiter.
- */
- if (VOP_ISLOCKED(dp) == LK_EXCLUSIVE) {
- crosslkflags &= ~LK_SHARED;
- crosslkflags |= LK_EXCLUSIVE | LK_CANRECURSE;
- } else if ((crosslkflags & LK_EXCLUSIVE) != 0) {
- vn_lock(dp, LK_UPGRADE | LK_RETRY);
- if (VN_IS_DOOMED(dp)) {
- error = ENOENT;
- goto bad2;
- }
- if (dp->v_mountedhere != mp) {
- continue;
- }
- } else
- crosslkflags &= ~LK_NODDLKTREAT;
+ error = vfs_busy(mp, MBF_NOWAIT);
+ if (__predict_false(error != 0)) {
+ int lkflags = compute_cn_lkflags(dp->v_mount,
+ cnp->cn_lkflags, cnp->cn_flags);
+ VOP_UNLOCK(dp);
+ error = vfs_busy(mp, 0);
+ vn_lock(dp, lkflags | LK_RETRY);
+ if (error != 0) {
+ error = 0;
+ continue;
+ } else if (dp->v_mountedhere != mp) {
+ vfs_unbusy(mp);
+ continue;
+ }
}
- if (vfs_busy(mp, 0) != 0)
- continue;
- if (__predict_true(!crosslock))
- vput(dp);
+ vput(dp);
if (dp != ndp->ni_dvp)
vput(ndp->ni_dvp);
else
@@ -1342,8 +1326,6 @@
ndp->ni_dvp = vp_crossmp;
error = VFS_ROOT(mp, crosslkflags, &tdp);
vfs_unbusy(mp);
- if (__predict_false(crosslock))
- vput(dp);
if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
panic("vp_crossmp exclusively locked or reclaimed");
if (error != 0) {
diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -1814,7 +1814,7 @@
}
static void
-dounmount_cleanup(struct mount *mp, struct vnode *coveredvp, int mntkflags)
+dounmount_cleanup(struct mount *mp, int mntkflags)
{
mtx_assert(MNT_MTX(mp), MA_OWNED);
@@ -1825,10 +1825,6 @@
}
vfs_op_exit_locked(mp);
MNT_IUNLOCK(mp);
- if (coveredvp != NULL) {
- VOP_UNLOCK(coveredvp);
- vdrop(coveredvp);
- }
vn_finished_write(mp);
vfs_rel(mp);
}
@@ -2125,7 +2121,6 @@
struct vnode *coveredvp, *rootvp;
int error;
uint64_t async_flag;
- int mnt_gen_r;
unsigned int retries;
KASSERT((flags & MNT_DEFERRED) == 0 ||
@@ -2235,24 +2230,6 @@
if ((flags & MNT_DEFERRED) != 0)
vfs_ref(mp);
- if ((coveredvp = mp->mnt_vnodecovered) != NULL) {
- mnt_gen_r = mp->mnt_gen;
- VI_LOCK(coveredvp);
- vholdl(coveredvp);
- vn_lock(coveredvp, LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY);
- /*
- * Check for mp being unmounted while waiting for the
- * covered vnode lock.
- */
- if (coveredvp->v_mountedhere != mp ||
- coveredvp->v_mountedhere->mnt_gen != mnt_gen_r) {
- VOP_UNLOCK(coveredvp);
- vdrop(coveredvp);
- vfs_rel(mp);
- return (EBUSY);
- }
- }
-
vfs_op_enter(mp);
vn_start_write(NULL, &mp, V_WAIT);
@@ -2260,12 +2237,12 @@
if ((mp->mnt_kern_flag & MNTK_UNMOUNT) != 0 ||
(mp->mnt_flag & MNT_UPDATE) != 0 ||
!TAILQ_EMPTY(&mp->mnt_uppers)) {
- dounmount_cleanup(mp, coveredvp, 0);
+ dounmount_cleanup(mp, 0);
return (EBUSY);
}
mp->mnt_kern_flag |= MNTK_UNMOUNT;
rootvp = vfs_cache_root_clear(mp);
- if (coveredvp != NULL)
+ if ((coveredvp = mp->mnt_vnodecovered) != NULL)
vn_seqc_write_begin(coveredvp);
if (flags & MNT_NONBUSY) {
MNT_IUNLOCK(mp);
@@ -2273,7 +2250,7 @@
MNT_ILOCK(mp);
if (error != 0) {
vn_seqc_write_end(coveredvp);
- dounmount_cleanup(mp, coveredvp, MNTK_UNMOUNT);
+ dounmount_cleanup(mp, MNTK_UNMOUNT);
if (rootvp != NULL) {
vn_seqc_write_end(rootvp);
vrele(rootvp);
@@ -2297,6 +2274,9 @@
mp->mnt_kern_flag |= MNTK_DRAINING;
error = msleep(&mp->mnt_lockref, MNT_MTX(mp), PVFS,
"mount drain", 0);
+ KASSERT((mp->mnt_kern_flag & MNTK_DRAINING) == 0,
+ ("%s: MNTK_DRAINING not cleared on mp %p @ %s:%d",
+ __func__, mp, __FILE__, __LINE__));
}
MNT_IUNLOCK(mp);
KASSERT(mp->mnt_lockref == 0,
@@ -2306,6 +2286,16 @@
("%s: invalid return value for msleep in the drain path @ %s:%d",
__func__, __FILE__, __LINE__));
+ if (coveredvp != NULL) {
+ vn_lock(coveredvp, LK_EXCLUSIVE | LK_RETRY);
+ KASSERT(coveredvp->v_mountedhere == mp,
+ ("%s: coveredvp->v_mountedhere(%p) != mp(%p) with MNTK_UNMOUNT set",
+ __func__, coveredvp->v_mountedhere, mp));
+ KASSERT(mp->mnt_vnodecovered == coveredvp,
+ ("%s: mp->mnt_vnodecovered(%p) != coveredvp(%p) with MNTK_UNMOUNT set",
+ __func__, mp->mnt_vnodecovered, coveredvp));
+ }
+
/*
* We want to keep the vnode around so that we can vn_seqc_write_end
* after we are done with unmount. Downgrade our reference to a mere
@@ -2356,7 +2346,6 @@
if (coveredvp) {
vn_seqc_write_end(coveredvp);
VOP_UNLOCK(coveredvp);
- vdrop(coveredvp);
}
if (rootvp != NULL) {
vn_seqc_write_end(rootvp);
@@ -2376,7 +2365,6 @@
vn_seqc_write_end_locked(coveredvp);
VI_UNLOCK(coveredvp);
VOP_UNLOCK(coveredvp);
- vdrop(coveredvp);
}
mount_devctl_event("UNMOUNT", mp, false);
if (rootvp != NULL) {

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