cifs: add routines to build sessions and tcons on the fly

This patch is rather large, but it's a bit difficult to do piecemeal...

For non-multiuser mounts, everything will basically work as it does
today. A call to cifs_sb_tlink will return the "master" tcon link.

Turn the tcon pointer in the cifs_sb into a radix tree that uses the
fsuid of the process as a key. The value is a new "tcon_link" struct
that contains info about a tcon that's under construction.

When a new process needs a tcon, it'll call cifs_sb_tcon. That will
then look up the tcon_link in the radix tree. If it exists and is
valid, it's returned.

If it doesn't exist, then we stuff a new tcon_link into the tree and
mark it as pending and then go and try to build the session/tcon.
If that works, the tcon pointer in the tcon_link is updated and the
pending flag is cleared.

If the construction fails, then we set the tcon pointer to an ERR_PTR
and clear the pending flag.

If the radix tree is searched and the tcon_link is marked pending
then we go to sleep and wait for the pending flag to be cleared.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 13 insertions, 19 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index d5324853203b..9a7c472a153f 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -317,42 +317,36 @@ struct cifsTconInfo {
  * "get" on the container.
  */
 struct tcon_link {
-        spinlock_t              tl_lock;
-        u32                     tl_count;
-        u64                     tl_time;
+        unsigned long           tl_index;
+        unsigned long           tl_flags;
+#define TCON_LINK_MASTER        0
+#define TCON_LINK_PENDING       1
+#define TCON_LINK_IN_TREE       2
+        unsigned long           tl_time;
+        atomic_t                tl_count;
         struct cifsTconInfo     *tl_tcon;
 };
 
-static inline struct tcon_link *
-cifs_sb_tlink(struct cifs_sb_info *cifs_sb)
-{
-        return (struct tcon_link *)cifs_sb->ptcon;
-}
+extern struct tcon_link *cifs_sb_tlink(struct cifs_sb_info *cifs_sb);
 
 static inline struct cifsTconInfo *
 tlink_tcon(struct tcon_link *tlink)
 {
-        return (struct cifsTconInfo *)tlink;
+        return tlink->tl_tcon;
 }
 
-static inline void
-cifs_put_tlink(struct tcon_link *tlink)
-{
-        return;
-}
+extern void cifs_put_tlink(struct tcon_link *tlink);
 
 static inline struct tcon_link *
 cifs_get_tlink(struct tcon_link *tlink)
 {
+        if (tlink && !IS_ERR(tlink))
+                atomic_inc(&tlink->tl_count);
         return tlink;
 }
 
 /* This function is always expected to succeed */
-static inline struct cifsTconInfo *
-cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb)
-{
-        return cifs_sb->ptcon;
-}
+extern struct cifsTconInfo *cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb);
 
 /*
  * This info hangs off the cifsFileInfo structure, pointed to by llist.