Differential D21574 Diff 62183 head/sys/kern/vfs_subr.c

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head/sys/kern/vfs_subr.c

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*/		*/
int		int
vfs_busy(struct mount *mp, int flags)		vfs_busy(struct mount *mp, int flags)
{		{

MPASS((flags & ~MBF_MASK) == 0);		MPASS((flags & ~MBF_MASK) == 0);
CTR3(KTR_VFS, "%s: mp %p with flags %d", __func__, mp, flags);		CTR3(KTR_VFS, "%s: mp %p with flags %d", __func__, mp, flags);

		if (vfs_op_thread_enter(mp)) {
		MPASS((mp->mnt_kern_flag & MNTK_DRAINING) == 0);
		MPASS((mp->mnt_kern_flag & MNTK_UNMOUNT) == 0);
		MPASS((mp->mnt_kern_flag & MNTK_REFEXPIRE) == 0);
		MNT_REF_UNLOCKED(mp);
		atomic_add_int(&mp->mnt_lockref, 1);
		vfs_op_thread_exit(mp);
		if (flags & MBF_MNTLSTLOCK)
		mtx_unlock(&mountlist_mtx);
		return (0);
		}

MNT_ILOCK(mp);		MNT_ILOCK(mp);
MNT_REF(mp);		MNT_REF(mp);
/*		/*
* If mount point is currently being unmounted, sleep until the		* If mount point is currently being unmounted, sleep until the
* mount point fate is decided. If thread doing the unmounting fails,		* mount point fate is decided. If thread doing the unmounting fails,
* it will clear MNTK_UNMOUNT flag before waking us up, indicating		* it will clear MNTK_UNMOUNT flag before waking us up, indicating
* that this mount point has survived the unmount attempt and vfs_busy		* that this mount point has survived the unmount attempt and vfs_busy
* should retry. Otherwise the unmounter thread will set MNTK_REFEXPIRE		* should retry. Otherwise the unmounter thread will set MNTK_REFEXPIRE
Show All 16 Lines	while (mp->mnt_kern_flag & MNTK_UNMOUNT) {
mp->mnt_kern_flag \|= MNTK_MWAIT;		mp->mnt_kern_flag \|= MNTK_MWAIT;
msleep(mp, MNT_MTX(mp), PVFS \| PDROP, "vfs_busy", 0);		msleep(mp, MNT_MTX(mp), PVFS \| PDROP, "vfs_busy", 0);
if (flags & MBF_MNTLSTLOCK)		if (flags & MBF_MNTLSTLOCK)
mtx_lock(&mountlist_mtx);		mtx_lock(&mountlist_mtx);
MNT_ILOCK(mp);		MNT_ILOCK(mp);
}		}
if (flags & MBF_MNTLSTLOCK)		if (flags & MBF_MNTLSTLOCK)
mtx_unlock(&mountlist_mtx);		mtx_unlock(&mountlist_mtx);
mp->mnt_lockref++;		atomic_add_int(&mp->mnt_lockref, 1);
MNT_IUNLOCK(mp);		MNT_IUNLOCK(mp);
return (0);		return (0);
}		}

/*		/*
* Free a busy filesystem.		* Free a busy filesystem.
*/		*/
void		void
vfs_unbusy(struct mount *mp)		vfs_unbusy(struct mount *mp)
{		{
		int c;

CTR2(KTR_VFS, "%s: mp %p", __func__, mp);		CTR2(KTR_VFS, "%s: mp %p", __func__, mp);

		if (vfs_op_thread_enter(mp)) {
		MPASS((mp->mnt_kern_flag & MNTK_DRAINING) == 0);
		c = atomic_fetchadd_int(&mp->mnt_lockref, -1) - 1;
		KASSERT(c >= 0, ("%s: negative mnt_lockref %d\n", __func__, c));
		MNT_REL_UNLOCKED(mp);
		vfs_op_thread_exit(mp);
		return;
		}

MNT_ILOCK(mp);		MNT_ILOCK(mp);
MNT_REL(mp);		MNT_REL(mp);
KASSERT(mp->mnt_lockref > 0, ("negative mnt_lockref"));		c = atomic_fetchadd_int(&mp->mnt_lockref, -1) - 1;
mp->mnt_lockref--;		KASSERT(c >= 0, ("%s: negative mnt_lockref %d\n", __func__, c));
if (mp->mnt_lockref == 0 && (mp->mnt_kern_flag & MNTK_DRAINING) != 0) {		if (c == 0 && (mp->mnt_kern_flag & MNTK_DRAINING) != 0) {
MPASS(mp->mnt_kern_flag & MNTK_UNMOUNT);		MPASS(mp->mnt_kern_flag & MNTK_UNMOUNT);
CTR1(KTR_VFS, "%s: waking up waiters", __func__);		CTR1(KTR_VFS, "%s: waking up waiters", __func__);
mp->mnt_kern_flag &= ~MNTK_DRAINING;		mp->mnt_kern_flag &= ~MNTK_DRAINING;
wakeup(&mp->mnt_lockref);		wakeup(&mp->mnt_lockref);
}		}
MNT_IUNLOCK(mp);		MNT_IUNLOCK(mp);
}		}

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