From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 fs/coda/cache.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)
 create mode 100644 fs/coda/cache.c

(limited to 'fs/coda/cache.c')

diff --git a/fs/coda/cache.c b/fs/coda/cache.c
new file mode 100644
index 000000000..5bb630a76
--- /dev/null
+++ b/fs/coda/cache.c
@@ -0,0 +1,118 @@
+/*
+ * 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 <linux/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);
+	list_for_each_entry(de, &parent->d_subdirs, d_child) {
+		/* don't know what to do with negative dentries */
+		if (d_inode(de) ) 
+			coda_flag_inode(d_inode(de), flag);
+	}
+	spin_unlock(&parent->d_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);
+}
+
-- 
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