lockd: save lock state on deferral

We need to keep some state for a pending asynchronous lock request, so this
patch adds that state to struct nlm_block.

This also adds a function which defers the request, by calling
rqstp->rq_chandle.defer and storing the resulting deferred request in a
nlm_block structure which we insert into lockd's global block list.  That
new function isn't called yet, so it's dead code until a later patch.

Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

2 files changed, 35 insertions, 0 deletions

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 3b0e7a4b817b..f2449265e2eb 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -331,6 +331,31 @@ static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 }
 
 /*
+ * Deferred lock request handling for non-blocking lock
+ */
+static u32
+nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
+{
+        u32 status = nlm_lck_denied_nolocks;
+
+        block->b_flags |= B_QUEUED;
+
+        nlmsvc_insert_block(block, NLM_TIMEOUT);
+
+        block->b_cache_req = &rqstp->rq_chandle;
+        if (rqstp->rq_chandle.defer) {
+                block->b_deferred_req =
+                        rqstp->rq_chandle.defer(block->b_cache_req);
+                if (block->b_deferred_req != NULL)
+                        status = nlm_drop_reply;
+        }
+        dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
+                block, block->b_flags, status);
+
+        return status;
+}
+
+/*
  * Attempt to establish a lock, and if it can't be granted, block it
  * if required.
  */
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index ac25b5649c59..d4c4de753bca 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -119,6 +119,9 @@ struct nlm_file {
  * couldn't be granted because of a conflicting lock).
  */
 #define NLM_NEVER               (~(unsigned long) 0)
+/* timeout on non-blocking call: */
+#define NLM_TIMEOUT             (7 * HZ)
+
 struct nlm_block {
         struct kref             b_count;        /* Reference count */
         struct list_head        b_list;         /* linked list of all blocks */
@@ -130,6 +133,13 @@ struct nlm_block {
         unsigned int            b_id;           /* block id */
         unsigned char           b_granted;      /* VFS granted lock */
         struct nlm_file *       b_file;         /* file in question */
+        struct cache_req *      b_cache_req;    /* deferred request handling */
+        struct file_lock *      b_fl;           /* set for GETLK */
+        struct cache_deferred_req * b_deferred_req;
+        unsigned int            b_flags;        /* block flags */
+#define B_QUEUED                1       /* lock queued */
+#define B_GOT_CALLBACK          2       /* got lock or conflicting lock */
+#define B_TIMED_OUT             4       /* filesystem too slow to respond */
 };
 
 /*