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/*

 * 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/sched.h>

#include <linux/fs.h>

#include <linux/stat.h>

#include <linux/errno.h>

#include <linux/locks.h>

#include <asm/uaccess.h>

#include <linux/string.h>

#include <linux/list.h>

#include <linux/coda.h>

#include <linux/coda_linux.h>

#include <linux/coda_psdev.h>

#include <linux/coda_fs_i.h>

#include <linux/coda_cache.h>

/* replace or extend an acl cache hit */

void coda_cache_enter(struct inode *inode, int mask)

{

        struct coda_inode_info *cii = ITOC(inode);

        if ( !coda_cred_ok(&cii->c_cached_cred) ) {

                coda_load_creds(&cii->c_cached_cred);

                cii->c_cached_perm = mask;

        } else

                cii->c_cached_perm |= mask;

}

/* remove cached acl from an inode */

void coda_cache_clear_inode(struct inode *inode)

{

        struct coda_inode_info *cii = ITOC(inode);

        cii->c_cached_perm = 0;

}

/* remove all acl caches for a principal (or all principals when cred == NULL)*/

void coda_cache_clear_all(struct super_block *sb, struct coda_cred *cred)

{

        struct coda_sb_info *sbi;

        struct coda_inode_info *cii;

        struct list_head *tmp;

        sbi = coda_sbp(sb);

        if (!sbi) BUG();

        list_for_each(tmp, &sbi->sbi_cihead)

        {

                cii = list_entry(tmp, struct coda_inode_info, c_cilist);

                if (!cred || coda_cred_eq(cred, &cii->c_cached_cred))

                        cii->c_cached_perm = 0;

        }

}

/* 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;

        hit = ((mask & cii->c_cached_perm) == mask) &&

                coda_cred_ok(&cii->c_cached_cred);

        CDEBUG(D_CACHE, "%s for ino %ld\n", hit ? "HIT" : "MISS", inode->i_ino);

        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 list_head *child;

        struct dentry *de;

        spin_lock(&dcache_lock);

        list_for_each(child, &parent->d_subdirs)

        {

                de = list_entry(child, struct dentry, d_child);

                /* don't know what to do with negative dentries */

                if ( ! de->d_inode )

                        continue;

                CDEBUG(D_DOWNCALL, "%d for %*s/%*s\n", flag,

                       de->d_name.len, de->d_name.name,

                       de->d_parent->d_name.len, de->d_parent->d_name.name);

                coda_flag_inode(de->d_inode, flag);

        }

        spin_unlock(&dcache_lock);

        return;

}

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);

}