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1// SPDX-License-Identifier: GPL-2.02/*3 * Cache operations for Coda.4 * For Linux 2.1: (C) 1997 Carnegie Mellon University5 * For Linux 2.3: (C) 2000 Carnegie Mellon University6 *7 * Carnegie Mellon encourages users of this code to contribute improvements8 * to the Coda project http://www.coda.cs.cmu.edu/ <coda@cs.cmu.edu>.9 */10 11#include <linux/types.h>12#include <linux/kernel.h>13#include <linux/time.h>14#include <linux/fs.h>15#include <linux/stat.h>16#include <linux/errno.h>17#include <linux/uaccess.h>18#include <linux/string.h>19#include <linux/list.h>20#include <linux/sched.h>21#include <linux/spinlock.h>22 23#include <linux/coda.h>24#include "coda_psdev.h"25#include "coda_linux.h"26#include "coda_cache.h"27 28static atomic_t permission_epoch = ATOMIC_INIT(0);29 30/* replace or extend an acl cache hit */31void coda_cache_enter(struct inode *inode, int mask)32{33 struct coda_inode_info *cii = ITOC(inode);34 35 spin_lock(&cii->c_lock);36 cii->c_cached_epoch = atomic_read(&permission_epoch);37 if (!uid_eq(cii->c_uid, current_fsuid())) {38 cii->c_uid = current_fsuid();39 cii->c_cached_perm = mask;40 } else41 cii->c_cached_perm |= mask;42 spin_unlock(&cii->c_lock);43}44 45/* remove cached acl from an inode */46void coda_cache_clear_inode(struct inode *inode)47{48 struct coda_inode_info *cii = ITOC(inode);49 spin_lock(&cii->c_lock);50 cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;51 spin_unlock(&cii->c_lock);52}53 54/* remove all acl caches */55void coda_cache_clear_all(struct super_block *sb)56{57 atomic_inc(&permission_epoch);58}59 60 61/* check if the mask has been matched against the acl already */62int coda_cache_check(struct inode *inode, int mask)63{64 struct coda_inode_info *cii = ITOC(inode);65 int hit;66 67 spin_lock(&cii->c_lock);68 hit = (mask & cii->c_cached_perm) == mask &&69 uid_eq(cii->c_uid, current_fsuid()) &&70 cii->c_cached_epoch == atomic_read(&permission_epoch);71 spin_unlock(&cii->c_lock);72 73 return hit;74}75 76 77/* Purging dentries and children */78/* The following routines drop dentries which are not79 in use and flag dentries which are in use to be 80 zapped later.81 82 The flags are detected by:83 - coda_dentry_revalidate (for lookups) if the flag is C_PURGE84 - coda_dentry_delete: to remove dentry from the cache when d_count85 falls to zero86 - an inode method coda_revalidate (for attributes) if the 87 flag is C_VATTR88*/89 90/* this won't do any harm: just flag all children */91static void coda_flag_children(struct dentry *parent, int flag)92{93 struct dentry *de;94 95 spin_lock(&parent->d_lock);96 hlist_for_each_entry(de, &parent->d_children, d_sib) {97 struct inode *inode = d_inode_rcu(de);98 /* don't know what to do with negative dentries */99 if (inode)100 coda_flag_inode(inode, flag);101 }102 spin_unlock(&parent->d_lock);103}104 105void coda_flag_inode_children(struct inode *inode, int flag)106{107 struct dentry *alias_de;108 109 if ( !inode || !S_ISDIR(inode->i_mode)) 110 return; 111 112 alias_de = d_find_alias(inode);113 if (!alias_de)114 return;115 coda_flag_children(alias_de, flag);116 shrink_dcache_parent(alias_de);117 dput(alias_de);118}119 120