#ifndef NET_9P_CLIENT_H
#define NET_9P_CLIENT_H
+/* Number of requests per row */
+#define P9_ROW_MAXTAG 255
+
/**
* enum p9_trans_status - different states of underlying transports
* @Connected: transport is connected and healthy
};
/**
+ * enum p9_req_status_t - virtio request status
+ * @REQ_STATUS_IDLE: request slot unused
+ * @REQ_STATUS_ALLOC: request has been allocated but not sent
+ * @REQ_STATUS_SENT: request sent to server
+ * @REQ_STATUS_FLSH: a flush has been sent for this request
+ * @REQ_STATUS_RCVD: response received from server
+ * @REQ_STATUS_FLSHD: request has been flushed
+ * @REQ_STATUS_ERR: request encountered an error on the client side
+ *
+ * The @REQ_STATUS_IDLE state is used to mark a request slot as unused
+ * but use is actually tracked by the idpool structure which handles tag
+ * id allocation.
+ *
+ */
+
+enum p9_req_status_t {
+ REQ_STATUS_IDLE,
+ REQ_STATUS_ALLOC,
+ REQ_STATUS_SENT,
+ REQ_STATUS_FLSH,
+ REQ_STATUS_RCVD,
+ REQ_STATUS_FLSHD,
+ REQ_STATUS_ERROR,
+};
+
+/**
+ * struct p9_req_t - request slots
+ * @status: status of this request slot
+ * @t_err: transport error
+ * @wq: wait_queue for the client to block on for this request
+ * @tc: the request fcall structure
+ * @rc: the response fcall structure
+ * @aux: transport specific data (provided for trans_fd migration)
+ *
+ * Transport use an array to track outstanding requests
+ * instead of a list. While this may incurr overhead during initial
+ * allocation or expansion, it makes request lookup much easier as the
+ * tag id is a index into an array. (We use tag+1 so that we can accomodate
+ * the -1 tag for the T_VERSION request).
+ * This also has the nice effect of only having to allocate wait_queues
+ * once, instead of constantly allocating and freeing them. Its possible
+ * other resources could benefit from this scheme as well.
+ *
+ */
+
+struct p9_req_t {
+ int status;
+ int t_err;
+ wait_queue_head_t *wq;
+ struct p9_fcall *tc;
+ struct p9_fcall *rc;
+ u16 flush_tag;
+ void *aux;
+};
+
+/**
* struct p9_client - per client instance state
* @lock: protect @fidlist
* @msize: maximum data size negotiated by protocol
* @conn: connection state information used by trans_fd
* @fidpool: fid handle accounting for session
* @fidlist: List of active fid handles
+ * @tagpool - transaction id accounting for session
+ * @reqs - 2D array of requests
+ * @max_tag - current maximum tag id allocated
*
* The client structure is used to keep track of various per-client
* state that has been instantiated.
+ * In order to minimize per-transaction overhead we use a
+ * simple array to lookup requests instead of a hash table
+ * or linked list. In order to support larger number of
+ * transactions, we make this a 2D array, allocating new rows
+ * when we need to grow the total number of the transactions.
+ *
+ * Each row is 256 requests and we'll support up to 256 rows for
+ * a total of 64k concurrent requests per session.
*
* Bugs: duplicated data and potentially unnecessary elements.
*/
struct p9_idpool *fidpool;
struct list_head fidlist;
+
+ struct p9_idpool *tagpool;
+ struct p9_req_t *reqs[P9_ROW_MAXTAG];
+ int max_tag;
};
/**
int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst);
struct p9_stat *p9_client_dirread(struct p9_fid *fid, u64 offset);
+struct p9_req_t *p9_tag_alloc(struct p9_client *, u16);
+struct p9_req_t *p9_tag_lookup(struct p9_client *, u16);
+
#endif /* NET_9P_CLIENT_H */
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;
goto error;
}
+ p9_tag_init(clnt);
+
err = parse_opts(options, clnt);
if (err < 0)
goto error;
if (clnt->fidpool)
p9_idpool_destroy(clnt->fidpool);
+ p9_tag_cleanup(clnt);
+
kfree(clnt);
}
EXPORT_SYMBOL(p9_client_destroy);
/*
- * The Guest 9p transport driver
+ * The Virtio 9p transport driver
*
* This is a block based transport driver based on the lguest block driver
* code.
*
- */
-/*
- * Copyright (C) 2007 Eric Van Hensbergen, IBM Corporation
+ * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
*
* Based on virtio console driver
* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
/* global which tracks highest initialized channel */
static int chan_index;
-#define P9_INIT_MAXTAG 16
-
-/**
- * enum p9_req_status_t - virtio request status
- * @REQ_STATUS_IDLE: request slot unused
- * @REQ_STATUS_SENT: request sent to server
- * @REQ_STATUS_RCVD: response received from server
- * @REQ_STATUS_FLSH: request has been flushed
- *
- * The @REQ_STATUS_IDLE state is used to mark a request slot as unused
- * but use is actually tracked by the idpool structure which handles tag
- * id allocation.
- *
- */
-
-enum p9_req_status_t {
- REQ_STATUS_IDLE,
- REQ_STATUS_SENT,
- REQ_STATUS_RCVD,
- REQ_STATUS_FLSH,
-};
-
-/**
- * struct p9_req_t - virtio request slots
- * @status: status of this request slot
- * @wq: wait_queue for the client to block on for this request
- *
- * The virtio transport uses an array to track outstanding requests
- * instead of a list. While this may incurr overhead during initial
- * allocation or expansion, it makes request lookup much easier as the
- * tag id is a index into an array. (We use tag+1 so that we can accomodate
- * the -1 tag for the T_VERSION request).
- * This also has the nice effect of only having to allocate wait_queues
- * once, instead of constantly allocating and freeing them. Its possible
- * other resources could benefit from this scheme as well.
- *
- */
-
-struct p9_req_t {
- int status;
- wait_queue_head_t *wq;
-};
-
/**
* struct virtio_chan - per-instance transport information
* @initialized: whether the channel is initialized
spinlock_t lock;
+ struct p9_client *client;
struct virtio_device *vdev;
struct virtqueue *vq;
- struct p9_idpool *tagpool;
- struct p9_req_t *reqs;
- int max_tag;
-
/* Scatterlist: can be too big for stack. */
struct scatterlist sg[VIRTQUEUE_NUM];
} channels[MAX_9P_CHAN];
-/**
- * p9_lookup_tag - Lookup requests by tag
- * @c: virtio channel 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.
- *
- * Bugs: there is currently no upper limit on request slots set
- * here, but that should be constrained by the id accounting.
- */
-
-static struct p9_req_t *p9_lookup_tag(struct virtio_chan *c, u16 tag)
-{
- /* This looks up the original request by tag so we know which
- * buffer to read the data into */
- tag++;
-
- while (tag >= c->max_tag) {
- int old_max = c->max_tag;
- int count;
-
- if (c->max_tag)
- c->max_tag *= 2;
- else
- c->max_tag = P9_INIT_MAXTAG;
-
- c->reqs = krealloc(c->reqs, sizeof(struct p9_req_t)*c->max_tag,
- GFP_ATOMIC);
- if (!c->reqs) {
- printk(KERN_ERR "Couldn't grow tag array\n");
- BUG();
- }
- for (count = old_max; count < c->max_tag; count++) {
- c->reqs[count].status = REQ_STATUS_IDLE;
- c->reqs[count].wq = kmalloc(sizeof(wait_queue_head_t),
- GFP_ATOMIC);
- if (!c->reqs[count].wq) {
- printk(KERN_ERR "Couldn't grow tag array\n");
- BUG();
- }
- init_waitqueue_head(c->reqs[count].wq);
- }
- }
-
- return &c->reqs[tag];
-}
-
-
/* How many bytes left in this page. */
static unsigned int rest_of_page(void *data)
{
static void p9_virtio_close(struct p9_client *client)
{
struct virtio_chan *chan = client->trans;
- int count;
- unsigned long flags;
-
- spin_lock_irqsave(&chan->lock, flags);
- p9_idpool_destroy(chan->tagpool);
- for (count = 0; count < chan->max_tag; count++)
- kfree(chan->reqs[count].wq);
- kfree(chan->reqs);
- chan->max_tag = 0;
- spin_unlock_irqrestore(&chan->lock, flags);
mutex_lock(&virtio_9p_lock);
chan->inuse = false;
mutex_unlock(&virtio_9p_lock);
-
- client->trans = NULL;
}
/**
spin_lock_irqsave(&chan->lock, flags);
while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
- req = p9_lookup_tag(chan, rc->tag);
+ req = p9_tag_lookup(chan->client, rc->tag);
req->status = REQ_STATUS_RCVD;
wake_up(req->wq);
}
n = P9_NOTAG;
if (tc->id != P9_TVERSION) {
- n = p9_idpool_get(chan->tagpool);
+ n = p9_idpool_get(c->tagpool);
if (n < 0)
return -ENOMEM;
}
spin_lock_irqsave(&chan->lock, flags);
- req = p9_lookup_tag(chan, n);
+ req = p9_tag_alloc(c, n);
spin_unlock_irqrestore(&chan->lock, flags);
p9_set_tag(tc, n);
}
#endif
- if (n != P9_NOTAG && p9_idpool_check(n, chan->tagpool))
- p9_idpool_put(n, chan->tagpool);
+ if (n != P9_NOTAG && p9_idpool_check(n, c->tagpool))
+ p9_idpool_put(n, c->tagpool);
req->status = REQ_STATUS_IDLE;
return -ENODEV;
}
- chan->tagpool = p9_idpool_create();
- if (IS_ERR(chan->tagpool)) {
- printk(KERN_ERR "9p: couldn't allocate tagpool\n");
- return -ENOMEM;
- }
- p9_idpool_get(chan->tagpool); /* reserve tag 0 */
- chan->max_tag = 0;
- chan->reqs = NULL;
-
client->trans = (void *)chan;
+ chan->client = client;
return 0;
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / commitdiff