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>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/coda/dir.c b/fs/coda/dir.c
index ccd98b0f2b0..69fbbea75f1 100644
--- a/fs/coda/dir.c
+++ b/fs/coda/dir.c
@@ -18,6 +18,7 @@
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/smp_lock.h>
+#include <linux/spinlock.h>
 
 #include <asm/uaccess.h>
 
@@ -617,7 +618,9 @@ static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd)
                 goto out;
 
         /* clear the flags. */
+        spin_lock(&cii->c_lock);
         cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
+        spin_unlock(&cii->c_lock);
 
 bad:
         unlock_kernel();
@@ -691,7 +694,10 @@ int coda_revalidate_inode(struct dentry *dentry)
                         goto return_bad;
                 
                 coda_flag_inode_children(inode, C_FLUSH);
+
+                spin_lock(&cii->c_lock);
                 cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
+                spin_unlock(&cii->c_lock);
         }
 
 ok: