| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <E1G65Rj-0002hJ-00@dorka.pomaz.szeredi.hu>
Date: Thu, 27 Jul 2006 14:58:35 +0200
From: Miklos Szeredi <miklos@...redi.hu>
To: akpm@...l.org
CC: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 2/5] fuse: use jiffies_64
It is entirely possible (though rare) that jiffies half-wraps around,
while a dentry/inode remains in the cache. This could mean that the
dentry/inode is not invalidated for another half wraparound-time.
To get around this problem, use 64-bit jiffies. The only problem with
this is that dentry->d_time is 32 bits on 32-bit archs. So use
d_fsdata as the high 32 bits. This is an ugly hack, but far simpler,
than having to allocate private data just for this purpose.
Since 64-bit jiffies can be assumed never to wrap around, simple
comparison can be used, and a zero time value can represent "invalid".
Signed-off-by: Miklos Szeredi <miklos@...redi.hu>
---
Index: linux/fs/fuse/dir.c
===================================================================
--- linux.orig/fs/fuse/dir.c 2006-07-27 14:37:59.000000000 +0200
+++ linux/fs/fuse/dir.c 2006-07-27 14:38:04.000000000 +0200
@@ -14,6 +14,33 @@
#include <linux/sched.h>
#include <linux/namei.h>
+#if BITS_PER_LONG >= 64
+static inline void fuse_dentry_settime(struct dentry *entry, u64 time)
+{
+ entry->d_time = time;
+}
+
+static inline u64 fuse_dentry_time(struct dentry *entry)
+{
+ return entry->d_time;
+}
+#else
+/*
+ * On 32 bit archs store the high 32 bits of time in d_fsdata
+ */
+static void fuse_dentry_settime(struct dentry *entry, u64 time)
+{
+ entry->d_time = time;
+ entry->d_fsdata = (void *) (unsigned long) (time >> 32);
+}
+
+static u64 fuse_dentry_time(struct dentry *entry)
+{
+ return (u64) entry->d_time +
+ ((u64) (unsigned long) entry->d_fsdata << 32);
+}
+#endif
+
/*
* FUSE caches dentries and attributes with separate timeout. The
* time in jiffies until the dentry/attributes are valid is stored in
@@ -23,13 +50,13 @@
/*
* Calculate the time in jiffies until a dentry/attributes are valid
*/
-static unsigned long time_to_jiffies(unsigned long sec, unsigned long nsec)
+static u64 time_to_jiffies(unsigned long sec, unsigned long nsec)
{
if (sec || nsec) {
struct timespec ts = {sec, nsec};
- return jiffies + timespec_to_jiffies(&ts);
+ return get_jiffies_64() + timespec_to_jiffies(&ts);
} else
- return jiffies - 1;
+ return 0;
}
/*
@@ -38,7 +65,8 @@ static unsigned long time_to_jiffies(uns
*/
static void fuse_change_timeout(struct dentry *entry, struct fuse_entry_out *o)
{
- entry->d_time = time_to_jiffies(o->entry_valid, o->entry_valid_nsec);
+ fuse_dentry_settime(entry,
+ time_to_jiffies(o->entry_valid, o->entry_valid_nsec));
if (entry->d_inode)
get_fuse_inode(entry->d_inode)->i_time =
time_to_jiffies(o->attr_valid, o->attr_valid_nsec);
@@ -50,7 +78,7 @@ static void fuse_change_timeout(struct d
*/
void fuse_invalidate_attr(struct inode *inode)
{
- get_fuse_inode(inode)->i_time = jiffies - 1;
+ get_fuse_inode(inode)->i_time = 0;
}
/*
@@ -63,7 +91,7 @@ void fuse_invalidate_attr(struct inode *
*/
static void fuse_invalidate_entry_cache(struct dentry *entry)
{
- entry->d_time = jiffies - 1;
+ fuse_dentry_settime(entry, 0);
}
/*
@@ -105,7 +133,7 @@ static int fuse_dentry_revalidate(struct
if (inode && is_bad_inode(inode))
return 0;
- else if (time_after(jiffies, entry->d_time)) {
+ else if (fuse_dentry_time(entry) < get_jiffies_64()) {
int err;
struct fuse_entry_out outarg;
struct fuse_conn *fc;
@@ -669,7 +697,7 @@ static int fuse_revalidate(struct dentry
if (!fuse_allow_task(fc, current))
return -EACCES;
if (get_node_id(inode) != FUSE_ROOT_ID &&
- time_before_eq(jiffies, fi->i_time))
+ fi->i_time >= get_jiffies_64())
return 0;
return fuse_do_getattr(inode);
Index: linux/fs/fuse/fuse_i.h
===================================================================
--- linux.orig/fs/fuse/fuse_i.h 2006-07-27 14:35:14.000000000 +0200
+++ linux/fs/fuse/fuse_i.h 2006-07-27 14:38:04.000000000 +0200
@@ -59,7 +59,7 @@ struct fuse_inode {
struct fuse_req *forget_req;
/** Time in jiffies until the file attributes are valid */
- unsigned long i_time;
+ u64 i_time;
};
/** FUSE specific file data */
Index: linux/fs/fuse/inode.c
===================================================================
--- linux.orig/fs/fuse/inode.c 2006-07-27 14:35:15.000000000 +0200
+++ linux/fs/fuse/inode.c 2006-07-27 14:38:04.000000000 +0200
@@ -51,7 +51,7 @@ static struct inode *fuse_alloc_inode(st
return NULL;
fi = get_fuse_inode(inode);
- fi->i_time = jiffies - 1;
+ fi->i_time = 0;
fi->nodeid = 0;
fi->nlookup = 0;
fi->forget_req = fuse_request_alloc();
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists