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/include/linux/coda_fs_i.h b/include/linux/coda_fs_i.h
index b3ef0c4..e35071b 100644
--- a/include/linux/coda_fs_i.h
+++ b/include/linux/coda_fs_i.h
@@ -10,19 +10,24 @@
#include <linux/types.h>
#include <linux/list.h>
+#include <linux/spinlock.h>
#include <linux/coda.h>
/*
* coda fs inode data
+ * c_lock protects accesses to c_flags, c_mapcount, c_cached_epoch, c_uid and
+ * c_cached_perm.
+ * vfs_inode is set only when the inode is created and never changes.
+ * c_fid is set when the inode is created and should be considered immutable.
*/
struct coda_inode_info {
- struct CodaFid c_fid; /* Coda identifier */
- u_short c_flags; /* flags (see below) */
- struct list_head c_cilist; /* list of all coda inodes */
+ struct CodaFid c_fid; /* Coda identifier */
+ u_short c_flags; /* flags (see below) */
unsigned int c_mapcount; /* nr of times this inode is mapped */
unsigned int c_cached_epoch; /* epoch for cached permissions */
vuid_t c_uid; /* fsuid for cached permissions */
- unsigned int c_cached_perm; /* cached access permissions */
+ unsigned int c_cached_perm; /* cached access permissions */
+ spinlock_t c_lock;
struct inode vfs_inode;
};
diff --git a/include/linux/coda_linux.h b/include/linux/coda_linux.h
index dcc228a..2e914d0 100644
--- a/include/linux/coda_linux.h
+++ b/include/linux/coda_linux.h
@@ -89,7 +89,11 @@
/* this will not zap the inode away */
static __inline__ void coda_flag_inode(struct inode *inode, int flag)
{
- ITOC(inode)->c_flags |= flag;
+ struct coda_inode_info *cii = ITOC(inode);
+
+ spin_lock(&cii->c_lock);
+ cii->c_flags |= flag;
+ spin_unlock(&cii->c_lock);
}
#endif