// SPDX-License-Identifier: GPL-2.0/* * Cache operations for Coda. * For Linux 2.1: (C) 1997 Carnegie Mellon University * For Linux 2.3: (C) 2000 Carnegie Mellon University * * Carnegie Mellon encourages users of this code to contribute improvements * to the Coda project http://www.coda.cs.cmu.edu/ <coda@cs.cmu.edu>. */ #include <linux/types.h>#include <linux/kernel.h>#include <linux/time.h>#include <linux/fs.h>#include <linux/stat.h>#include <linux/errno.h>#include <linux/uaccess.h>#include <linux/string.h>#include <linux/list.h>#include <linux/sched.h>#include <linux/spinlock.h> #include <linux/coda.h>#include "coda_psdev.h"#include "coda_linux.h"#include "coda_cache.h" static atomic_t permission_epoch = ATOMIC_INIT(0); /* replace or extend an acl cache hit */void coda_cache_enter(struct inode *inode, int mask){	struct coda_inode_info *cii = ITOC(inode); 	spin_lock(&cii->c_lock);	cii->c_cached_epoch = atomic_read(&permission_epoch);	if (!uid_eq(cii->c_uid, current_fsuid())) {		cii->c_uid = current_fsuid();                cii->c_cached_perm = mask;        } else                cii->c_cached_perm |= mask;	spin_unlock(&cii->c_lock);} /* remove cached acl from an inode */void coda_cache_clear_inode(struct inode *inode){	struct coda_inode_info *cii = ITOC(inode);	spin_lock(&cii->c_lock);	cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;	spin_unlock(&cii->c_lock);} /* remove all acl caches */void coda_cache_clear_all(struct super_block *sb){	atomic_inc(&permission_epoch);}  /* check if the mask has been matched against the acl already */int coda_cache_check(struct inode *inode, int mask){	struct coda_inode_info *cii = ITOC(inode);	int hit;		spin_lock(&cii->c_lock);	hit = (mask & cii->c_cached_perm) == mask &&	    uid_eq(cii->c_uid, current_fsuid()) &&	    cii->c_cached_epoch == atomic_read(&permission_epoch);	spin_unlock(&cii->c_lock); 	return hit;}  /* Purging dentries and children *//* The following routines drop dentries which are not   in use and flag dentries which are in use to be    zapped later.    The flags are detected by:   - coda_dentry_revalidate (for lookups) if the flag is C_PURGE   - coda_dentry_delete: to remove dentry from the cache when d_count     falls to zero   - an inode method coda_revalidate (for attributes) if the      flag is C_VATTR*/ /* this won't do any harm: just flag all children */static void coda_flag_children(struct dentry *parent, int flag){	struct dentry *de; 	spin_lock(&parent->d_lock);	rcu_read_lock();	hlist_for_each_entry(de, &parent->d_children, d_sib) {		struct inode *inode = d_inode_rcu(de);		/* don't know what to do with negative dentries */		if (inode)			coda_flag_inode(inode, flag);	}	rcu_read_unlock();	spin_unlock(&parent->d_lock);} void coda_flag_inode_children(struct inode *inode, int flag){	struct dentry *alias_de; 	if ( !inode || !S_ISDIR(inode->i_mode)) 		return;  	alias_de = d_find_alias(inode);	if (!alias_de)		return;	coda_flag_children(alias_de, flag);	shrink_dcache_parent(alias_de);	dput(alias_de);}