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/cnode.c b/fs/coda/cnode.c
index a7a7809..6022405 100644
--- a/fs/coda/cnode.c
+++ b/fs/coda/cnode.c
@@ -45,13 +45,15 @@
static int coda_test_inode(struct inode *inode, void *data)
{
struct CodaFid *fid = (struct CodaFid *)data;
- return coda_fideq(&(ITOC(inode)->c_fid), fid);
+ struct coda_inode_info *cii = ITOC(inode);
+ return coda_fideq(&cii->c_fid, fid);
}
static int coda_set_inode(struct inode *inode, void *data)
{
struct CodaFid *fid = (struct CodaFid *)data;
- ITOC(inode)->c_fid = *fid;
+ struct coda_inode_info *cii = ITOC(inode);
+ cii->c_fid = *fid;
return 0;
}
@@ -71,6 +73,7 @@
cii = ITOC(inode);
/* we still need to set i_ino for things like stat(2) */
inode->i_ino = hash;
+ /* inode is locked and unique, no need to grab cii->c_lock */
cii->c_mapcount = 0;
unlock_new_inode(inode);
}
@@ -107,14 +110,20 @@
}
+/* Although we treat Coda file identifiers as immutable, there is one
+ * special case for files created during a disconnection where they may
+ * not be globally unique. When an identifier collision is detected we
+ * first try to flush the cached inode from the kernel and finally
+ * resort to renaming/rehashing in-place. Userspace remembers both old
+ * and new values of the identifier to handle any in-flight upcalls.
+ * The real solution is to use globally unique UUIDs as identifiers, but
+ * retrofitting the existing userspace code for this is non-trivial. */
void coda_replace_fid(struct inode *inode, struct CodaFid *oldfid,
struct CodaFid *newfid)
{
- struct coda_inode_info *cii;
+ struct coda_inode_info *cii = ITOC(inode);
unsigned long hash = coda_f2i(newfid);
- cii = ITOC(inode);
-
BUG_ON(!coda_fideq(&cii->c_fid, oldfid));
/* replace fid and rehash inode */