Coda: add spin lock to protect accesses to struct coda_inode_info.
We mostly need it to protect cached user permissions. The c_flags field
is advisory, reading the wrong value is harmless and in the worst case
we hit a slow path where we have to make an extra upcall to the
userspace cache manager when revalidating a dentry or inode.
Signed-off-by: Yoshihisa Abe <yoshiabe@cs.cmu.edu>
Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/coda/cache.c b/fs/coda/cache.c
index a5bf577..9060f08 100644
--- a/fs/coda/cache.c
+++ b/fs/coda/cache.c
@@ -17,6 +17,7 @@
#include <linux/string.h>
#include <linux/list.h>
#include <linux/sched.h>
+#include <linux/spinlock.h>
#include <linux/coda.h>
#include <linux/coda_linux.h>
@@ -31,19 +32,23 @@
{
struct coda_inode_info *cii = ITOC(inode);
+ spin_lock(&cii->c_lock);
cii->c_cached_epoch = atomic_read(&permission_epoch);
if (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 */
@@ -57,13 +62,15 @@
int coda_cache_check(struct inode *inode, int mask)
{
struct coda_inode_info *cii = ITOC(inode);
- int hit;
+ int hit;
- hit = (mask & cii->c_cached_perm) == mask &&
- cii->c_uid == current_fsuid() &&
- cii->c_cached_epoch == atomic_read(&permission_epoch);
+ spin_lock(&cii->c_lock);
+ hit = (mask & cii->c_cached_perm) == mask &&
+ cii->c_uid == current_fsuid() &&
+ cii->c_cached_epoch == atomic_read(&permission_epoch);
+ spin_unlock(&cii->c_lock);
- return hit;
+ return hit;
}