[ Upstream commit 996d5b4db4b191f2676cf8775565cab8a5e2753b ]
Replace the custom batch allocation with a slab. Use an IDR to store pointers to the active requests instead of an array. We don't try to handle P9_NOTAG specially; the IDR will happily shrink all the way back once the TVERSION call has completed.
Link: http://lkml.kernel.org/r/20180711210225.19730-6-willy@infradead.org Signed-off-by: Matthew Wilcox willy@infradead.org Cc: Eric Van Hensbergen ericvh@gmail.com Cc: Ron Minnich rminnich@sandia.gov Cc: Latchesar Ionkov lucho@ionkov.net Signed-off-by: Dominique Martinet dominique.martinet@cea.fr Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/9p/client.h | 51 ++------- net/9p/client.c | 238 ++++++++++++++-------------------------- net/9p/mod.c | 9 +- 3 files changed, 102 insertions(+), 196 deletions(-)
diff --git a/include/net/9p/client.h b/include/net/9p/client.h index 0fa0fbab33b0..a4dc42c53d18 100644 --- a/include/net/9p/client.h +++ b/include/net/9p/client.h @@ -64,22 +64,15 @@ enum p9_trans_status {
/** * enum p9_req_status_t - status of a request - * @REQ_STATUS_IDLE: request slot unused * @REQ_STATUS_ALLOC: request has been allocated but not sent * @REQ_STATUS_UNSENT: request waiting to be sent * @REQ_STATUS_SENT: request sent to server * @REQ_STATUS_RCVD: response received from server * @REQ_STATUS_FLSHD: request has been flushed * @REQ_STATUS_ERROR: 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_UNSENT, REQ_STATUS_SENT, @@ -92,24 +85,12 @@ enum p9_req_status_t { * struct p9_req_t - request slots * @status: status of this request slot * @t_err: transport error - * @flush_tag: tag of request being flushed (for flush requests) * @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) * @req_list: link for higher level objects to chain requests - * - * 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 accommodate - * 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; @@ -117,40 +98,26 @@ struct p9_req_t { struct p9_fcall *tc; struct p9_fcall *rc; void *aux; - struct list_head req_list; };
/** * struct p9_client - per client instance state - * @lock: protect @fidlist + * @lock: protect @fids and @reqs * @msize: maximum data size negotiated by protocol - * @dotu: extension flags negotiated by protocol * @proto_version: 9P protocol version to use * @trans_mod: module API instantiated with this client + * @status: connection state * @trans: tranport instance state and API * @fids: All active FID handles - * @tagpool - transaction id accounting for session - * @reqs - 2D array of requests - * @max_tag - current maximum tag id allocated - * @name - node name used as client id + * @reqs: All active requests. + * @name: node name used as client id * * 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_client { - spinlock_t lock; /* protect client structure */ + spinlock_t lock; unsigned int msize; unsigned char proto_version; struct p9_trans_module *trans_mod; @@ -170,10 +137,7 @@ struct p9_client { } trans_opts;
struct idr fids; - - struct p9_idpool *tagpool; - struct p9_req_t *reqs[P9_ROW_MAXTAG]; - int max_tag; + struct idr reqs;
char name[__NEW_UTS_LEN + 1]; }; @@ -279,4 +243,7 @@ struct p9_fid *p9_client_xattrwalk(struct p9_fid *, const char *, u64 *); int p9_client_xattrcreate(struct p9_fid *, const char *, u64, int); int p9_client_readlink(struct p9_fid *fid, char **target);
+int p9_client_init(void); +void p9_client_exit(void); + #endif /* NET_9P_CLIENT_H */ diff --git a/net/9p/client.c b/net/9p/client.c index 23ec6187dc07..d8949c59d46e 100644 --- a/net/9p/client.c +++ b/net/9p/client.c @@ -248,132 +248,102 @@ static struct p9_fcall *p9_fcall_alloc(int alloc_msize) return fc; }
+static struct kmem_cache *p9_req_cache; + /** - * 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 accommodate 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. + * p9_req_alloc - Allocate a new request. + * @c: Client session. + * @type: Transaction type. + * @max_size: Maximum packet size for this request. * + * Context: Process context. + * Return: Pointer to new request. */ - static struct p9_req_t * -p9_tag_alloc(struct p9_client *c, u16 tag, unsigned int max_size) +p9_tag_alloc(struct p9_client *c, int8_t type, unsigned int max_size) { - unsigned long flags; - int row, col; - struct p9_req_t *req; + struct p9_req_t *req = kmem_cache_alloc(p9_req_cache, GFP_NOFS); int alloc_msize = min(c->msize, max_size); + int tag;
- /* 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]) { - pr_err("Couldn't grow tag array\n"); - spin_unlock_irqrestore(&c->lock, flags); - return ERR_PTR(-ENOMEM); - } - for (col = 0; col < P9_ROW_MAXTAG; col++) { - req = &c->reqs[row][col]; - req->status = REQ_STATUS_IDLE; - init_waitqueue_head(&req->wq); - } - c->max_tag += P9_ROW_MAXTAG; - } - spin_unlock_irqrestore(&c->lock, flags); - } - row = tag / P9_ROW_MAXTAG; - col = tag % P9_ROW_MAXTAG; + if (!req) + return NULL;
- req = &c->reqs[row][col]; - if (!req->tc) - req->tc = p9_fcall_alloc(alloc_msize); - if (!req->rc) - req->rc = p9_fcall_alloc(alloc_msize); + req->tc = p9_fcall_alloc(alloc_msize); + req->rc = p9_fcall_alloc(alloc_msize); if (!req->tc || !req->rc) - goto grow_failed; + goto free;
p9pdu_reset(req->tc); p9pdu_reset(req->rc); - - req->tc->tag = tag-1; req->status = REQ_STATUS_ALLOC; + init_waitqueue_head(&req->wq); + INIT_LIST_HEAD(&req->req_list); + + idr_preload(GFP_NOFS); + spin_lock_irq(&c->lock); + if (type == P9_TVERSION) + tag = idr_alloc(&c->reqs, req, P9_NOTAG, P9_NOTAG + 1, + GFP_NOWAIT); + else + tag = idr_alloc(&c->reqs, req, 0, P9_NOTAG, GFP_NOWAIT); + req->tc->tag = tag; + spin_unlock_irq(&c->lock); + idr_preload_end(); + if (tag < 0) + goto free;
return req;
-grow_failed: - pr_err("Couldn't grow tag array\n"); +free: kfree(req->tc); kfree(req->rc); - req->tc = req->rc = NULL; + kmem_cache_free(p9_req_cache, req); return ERR_PTR(-ENOMEM); }
/** - * p9_tag_lookup - lookup a request by tag - * @c: client session to lookup tag within - * @tag: numeric id for transaction + * p9_tag_lookup - Look up a request by tag. + * @c: Client session. + * @tag: Transaction ID. * + * Context: Any context. + * Return: A request, or %NULL if there is no request with that tag. */ - 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++; - - if (tag >= c->max_tag) - return NULL; + struct p9_req_t *req;
- row = tag / P9_ROW_MAXTAG; - col = tag % P9_ROW_MAXTAG; + rcu_read_lock(); + req = idr_find(&c->reqs, tag); + /* There's no refcount on the req; a malicious server could cause + * us to dereference a NULL pointer + */ + rcu_read_unlock();
- return &c->reqs[row][col]; + return req; } EXPORT_SYMBOL(p9_tag_lookup);
/** - * p9_tag_init - setup tags structure and contents - * @c: v9fs client struct - * - * This initializes the tags structure for each client instance. + * p9_free_req - Free a request. + * @c: Client session. + * @r: Request to free. * + * Context: Any context. */ - -static int p9_tag_init(struct p9_client *c) +static void p9_free_req(struct p9_client *c, struct p9_req_t *r) { - int err = 0; + unsigned long flags; + u16 tag = r->tc->tag;
- c->tagpool = p9_idpool_create(); - if (IS_ERR(c->tagpool)) { - err = PTR_ERR(c->tagpool); - goto error; - } - err = p9_idpool_get(c->tagpool); /* reserve tag 0 */ - if (err < 0) { - p9_idpool_destroy(c->tagpool); - goto error; - } - c->max_tag = 0; -error: - return err; + p9_debug(P9_DEBUG_MUX, "clnt %p req %p tag: %d\n", c, r, tag); + spin_lock_irqsave(&c->lock, flags); + idr_remove(&c->reqs, tag); + spin_unlock_irqrestore(&c->lock, flags); + kfree(r->tc); + kfree(r->rc); + kmem_cache_free(p9_req_cache, r); }
/** @@ -385,52 +355,15 @@ static int p9_tag_init(struct p9_client *c) */ 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_debug(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_put(0, c->tagpool); /* free reserved tag 0 */ - p9_idpool_destroy(c->tagpool); - } + struct p9_req_t *req; + int id;
- /* 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].tc); - kfree(c->reqs[row][col].rc); - } - kfree(c->reqs[row]); + rcu_read_lock(); + idr_for_each_entry(&c->reqs, req, id) { + pr_info("Tag %d still in use\n", id); + p9_free_req(c, req); } - c->max_tag = 0; -} - -/** - * p9_free_req - free a request and clean-up as necessary - * c: client state - * r: request to release - * - */ - -static void p9_free_req(struct p9_client *c, struct p9_req_t *r) -{ - int tag = r->tc->tag; - p9_debug(P9_DEBUG_MUX, "clnt %p req %p tag: %d\n", c, r, tag); - - r->status = REQ_STATUS_IDLE; - if (tag != P9_NOTAG && p9_idpool_check(tag, c->tagpool)) - p9_idpool_put(tag, c->tagpool); + rcu_read_unlock(); }
/** @@ -704,7 +637,7 @@ static struct p9_req_t *p9_client_prepare_req(struct p9_client *c, int8_t type, int req_size, const char *fmt, va_list ap) { - int tag, err; + int err; struct p9_req_t *req;
p9_debug(P9_DEBUG_MUX, "client %p op %d\n", c, type); @@ -717,24 +650,17 @@ static struct p9_req_t *p9_client_prepare_req(struct p9_client *c, if ((c->status == BeginDisconnect) && (type != P9_TCLUNK)) return ERR_PTR(-EIO);
- tag = P9_NOTAG; - if (type != P9_TVERSION) { - tag = p9_idpool_get(c->tagpool); - if (tag < 0) - return ERR_PTR(-ENOMEM); - } - - req = p9_tag_alloc(c, tag, req_size); + req = p9_tag_alloc(c, type, req_size); if (IS_ERR(req)) return req;
/* marshall the data */ - p9pdu_prepare(req->tc, tag, type); + p9pdu_prepare(req->tc, req->tc->tag, type); err = p9pdu_vwritef(req->tc, c->proto_version, fmt, ap); if (err) goto reterr; p9pdu_finalize(c, req->tc); - trace_9p_client_req(c, type, tag); + trace_9p_client_req(c, type, req->tc->tag); return req; reterr: p9_free_req(c, req); @@ -1040,14 +966,11 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
spin_lock_init(&clnt->lock); idr_init(&clnt->fids); - - err = p9_tag_init(clnt); - if (err < 0) - goto free_client; + idr_init(&clnt->reqs);
err = parse_opts(options, clnt); if (err < 0) - goto destroy_tagpool; + goto free_client;
if (!clnt->trans_mod) clnt->trans_mod = v9fs_get_default_trans(); @@ -1056,7 +979,7 @@ struct p9_client *p9_client_create(const char *dev_name, char *options) err = -EPROTONOSUPPORT; p9_debug(P9_DEBUG_ERROR, "No transport defined or default transport\n"); - goto destroy_tagpool; + goto free_client; }
p9_debug(P9_DEBUG_MUX, "clnt %p trans %p msize %d protocol %d\n", @@ -1086,8 +1009,6 @@ struct p9_client *p9_client_create(const char *dev_name, char *options) clnt->trans_mod->close(clnt); put_trans: v9fs_put_trans(clnt->trans_mod); -destroy_tagpool: - p9_idpool_destroy(clnt->tagpool); free_client: kfree(clnt); return ERR_PTR(err); @@ -2303,3 +2224,14 @@ int p9_client_readlink(struct p9_fid *fid, char **target) return err; } EXPORT_SYMBOL(p9_client_readlink); + +int __init p9_client_init(void) +{ + p9_req_cache = KMEM_CACHE(p9_req_t, 0); + return p9_req_cache ? 0 : -ENOMEM; +} + +void __exit p9_client_exit(void) +{ + kmem_cache_destroy(p9_req_cache); +} diff --git a/net/9p/mod.c b/net/9p/mod.c index 253ba824a325..0da56d6af73b 100644 --- a/net/9p/mod.c +++ b/net/9p/mod.c @@ -171,11 +171,17 @@ void v9fs_put_trans(struct p9_trans_module *m) */ static int __init init_p9(void) { + int ret; + + ret = p9_client_init(); + if (ret) + return ret; + p9_error_init(); pr_info("Installing 9P2000 support\n"); p9_trans_fd_init();
- return 0; + return ret; }
/** @@ -188,6 +194,7 @@ static void __exit exit_p9(void) pr_info("Unloading 9P2000 support\n");
p9_trans_fd_exit(); + p9_client_exit(); }
module_init(init_p9)