diff options
| -rw-r--r-- | include/net/9p/client.h | 77 | ||||
| -rw-r--r-- | net/9p/client.c | 152 | ||||
| -rw-r--r-- | net/9p/trans_virtio.c | 136 |
3 files changed, 238 insertions, 127 deletions
diff --git a/include/net/9p/client.h b/include/net/9p/client.h index c35fb54..140cf1d 100644 --- a/include/net/9p/client.h +++ b/include/net/9p/client.h @@ -26,6 +26,9 @@ #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 @@ -43,6 +46,62 @@ enum p9_trans_status { }; /** + * 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 @@ -52,9 +111,20 @@ enum p9_trans_status { * @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. */ @@ -70,6 +140,10 @@ struct p9_client { struct p9_idpool *fidpool; struct list_head fidlist; + + struct p9_idpool *tagpool; + struct p9_req_t *reqs[P9_ROW_MAXTAG]; + int max_tag; }; /** @@ -131,4 +205,7 @@ struct p9_stat *p9_client_stat(struct p9_fid *fid); 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 */ diff --git a/net/9p/client.c b/net/9p/client.c index 712d4f3..8670319 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); diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 72493f0..36bce45 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -1,12 +1,10 @@ /* - * 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 @@ -54,49 +52,6 @@ static DEFINE_MUTEX(virtio_9p_lock); /* 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 @@ -121,67 +76,14 @@ static struct virtio_chan { 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) { @@ -200,22 +102,10 @@ 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; } /** @@ -241,7 +131,7 @@ static void req_done(struct virtqueue *vq) 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); } @@ -311,13 +201,13 @@ p9_virtio_rpc(struct p9_client *c, struct p9_fcall *tc, struct p9_fcall **rc) 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); @@ -357,8 +247,8 @@ p9_virtio_rpc(struct p9_client *c, struct p9_fcall *tc, struct p9_fcall **rc) } #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; @@ -463,16 +353,8 @@ p9_virtio_create(struct p9_client *client, const char *devname, char *args) 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; } |
