9p: move request management to client code

The virtio transport uses a simplified request management system
that I want to use for all transports.  This patch adapts and moves the
exisiting code for managing requests to the client common code.
Later patches will apply these mechanisms to the other transports.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 152 insertions, 0 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
index 712d4f336adc..867031934f75 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -120,6 +120,154 @@ static int parse_opts(char *opts, struct p9_client *clnt)
         return ret;
 }
 
+/**
+ * p9_tag_alloc - lookup/allocate a request by tag
+ * @c: client session to lookup tag within
+ * @tag: numeric id for transaction
+ *
+ * this is a simple array lookup, but will grow the
+ * request_slots as necessary to accomodate transaction
+ * ids which did not previously have a slot.
+ *
+ * this code relies on the client spinlock to manage locks, its
+ * possible we should switch to something else, but I'd rather
+ * stick with something low-overhead for the common case.
+ *
+ */
+
+struct p9_req_t *p9_tag_alloc(struct p9_client *c, u16 tag)
+{
+        unsigned long flags;
+        int row, col;
+
+        /* This looks up the original request by tag so we know which
+         * buffer to read the data into */
+        tag++;
+
+        if (tag >= c->max_tag) {
+                spin_lock_irqsave(&c->lock, flags);
+                /* check again since original check was outside of lock */
+                while (tag >= c->max_tag) {
+                        row = (tag / P9_ROW_MAXTAG);
+                        c->reqs[row] = kcalloc(P9_ROW_MAXTAG,
+                                        sizeof(struct p9_req_t), GFP_ATOMIC);
+
+                        if (!c->reqs[row]) {
+                                printk(KERN_ERR "Couldn't grow tag array\n");
+                                BUG();
+                        }
+                        for (col = 0; col < P9_ROW_MAXTAG; col++) {
+                                c->reqs[row][col].status = REQ_STATUS_IDLE;
+                                c->reqs[row][col].flush_tag = P9_NOTAG;
+                                c->reqs[row][col].wq = kmalloc(
+                                        sizeof(wait_queue_head_t), GFP_ATOMIC);
+                                if (!c->reqs[row][col].wq) {
+                                        printk(KERN_ERR
+                                                "Couldn't grow tag array\n");
+                                        BUG();
+                                }
+                                init_waitqueue_head(c->reqs[row][col].wq);
+                        }
+                        c->max_tag += P9_ROW_MAXTAG;
+                }
+                spin_unlock_irqrestore(&c->lock, flags);
+        }
+        row = tag / P9_ROW_MAXTAG;
+        col = tag % P9_ROW_MAXTAG;
+
+        c->reqs[row][col].status = REQ_STATUS_ALLOC;
+        c->reqs[row][col].flush_tag = P9_NOTAG;
+
+        return &c->reqs[row][col];
+}
+EXPORT_SYMBOL(p9_tag_alloc);
+
+/**
+ * p9_tag_lookup - lookup a request by tag
+ * @c: client session to lookup tag within
+ * @tag: numeric id for transaction
+ *
+ */
+
+struct p9_req_t *p9_tag_lookup(struct p9_client *c, u16 tag)
+{
+        int row, col;
+
+        /* This looks up the original request by tag so we know which
+         * buffer to read the data into */
+        tag++;
+
+        BUG_ON(tag >= c->max_tag);
+
+        row = tag / P9_ROW_MAXTAG;
+        col = tag % P9_ROW_MAXTAG;
+
+        return &c->reqs[row][col];
+}
+EXPORT_SYMBOL(p9_tag_lookup);
+
+/**
+ * p9_tag_init - setup tags structure and contents
+ * @tags: tags structure from the client struct
+ *
+ * This initializes the tags structure for each client instance.
+ *
+ */
+
+static int p9_tag_init(struct p9_client *c)
+{
+        int err = 0;
+
+        c->tagpool = p9_idpool_create();
+        if (IS_ERR(c->tagpool)) {
+                err = PTR_ERR(c->tagpool);
+                c->tagpool = NULL;
+                goto error;
+        }
+
+        p9_idpool_get(c->tagpool); /* reserve tag 0 */
+
+        c->max_tag = 0;
+error:
+        return err;
+}
+
+/**
+ * p9_tag_cleanup - cleans up tags structure and reclaims resources
+ * @tags: tags structure from the client struct
+ *
+ * This frees resources associated with the tags structure
+ *
+ */
+static void p9_tag_cleanup(struct p9_client *c)
+{
+        int row, col;
+
+        /* check to insure all requests are idle */
+        for (row = 0; row < (c->max_tag/P9_ROW_MAXTAG); row++) {
+                for (col = 0; col < P9_ROW_MAXTAG; col++) {
+                        if (c->reqs[row][col].status != REQ_STATUS_IDLE) {
+                                P9_DPRINTK(P9_DEBUG_MUX,
+                                  "Attempting to cleanup non-free tag %d,%d\n",
+                                  row, col);
+                                /* TODO: delay execution of cleanup */
+                                return;
+                        }
+                }
+        }
+
+        if (c->tagpool)
+                p9_idpool_destroy(c->tagpool);
+
+        /* free requests associated with tags */
+        for (row = 0; row < (c->max_tag/P9_ROW_MAXTAG); row++) {
+                for (col = 0; col < P9_ROW_MAXTAG; col++)
+                        kfree(c->reqs[row][col].wq);
+                kfree(c->reqs[row]);
+        }
+        c->max_tag = 0;
+}
+
 static struct p9_fid *p9_fid_create(struct p9_client *clnt)
 {
         int err;
@@ -209,6 +357,8 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
                 goto error;
         }
 
+        p9_tag_init(clnt);
+
         err = parse_opts(options, clnt);
         if (err < 0)
                 goto error;
@@ -285,6 +435,8 @@ void p9_client_destroy(struct p9_client *clnt)
         if (clnt->fidpool)
                 p9_idpool_destroy(clnt->fidpool);
 
+        p9_tag_cleanup(clnt);
+
         kfree(clnt);
 }
 EXPORT_SYMBOL(p9_client_destroy);