diff options
Diffstat (limited to '')
| -rw-r--r-- | net/sunrpc/backchannel_rqst.c | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c new file mode 100644 index 000000000..65a6c6429 --- /dev/null +++ b/net/sunrpc/backchannel_rqst.c @@ -0,0 +1,376 @@ +// SPDX-License-Identifier: GPL-2.0-only +/****************************************************************************** + +(c) 2007 Network Appliance, Inc. All Rights Reserved. +(c) 2009 NetApp. All Rights Reserved. + + +******************************************************************************/ + +#include <linux/tcp.h> +#include <linux/slab.h> +#include <linux/sunrpc/xprt.h> +#include <linux/export.h> +#include <linux/sunrpc/bc_xprt.h> + +#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) +#define RPCDBG_FACILITY RPCDBG_TRANS +#endif + +#define BC_MAX_SLOTS 64U + +unsigned int xprt_bc_max_slots(struct rpc_xprt *xprt) +{ + return BC_MAX_SLOTS; +} + +/* + * Helper routines that track the number of preallocation elements + * on the transport. + */ +static inline int xprt_need_to_requeue(struct rpc_xprt *xprt) +{ + return xprt->bc_alloc_count < xprt->bc_alloc_max; +} + +/* + * Free the preallocated rpc_rqst structure and the memory + * buffers hanging off of it. + */ +static void xprt_free_allocation(struct rpc_rqst *req) +{ + struct xdr_buf *xbufp; + + dprintk("RPC: free allocations for req= %p\n", req); + WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); + xbufp = &req->rq_rcv_buf; + free_page((unsigned long)xbufp->head[0].iov_base); + xbufp = &req->rq_snd_buf; + free_page((unsigned long)xbufp->head[0].iov_base); + kfree(req); +} + +static void xprt_bc_reinit_xdr_buf(struct xdr_buf *buf) +{ + buf->head[0].iov_len = PAGE_SIZE; + buf->tail[0].iov_len = 0; + buf->pages = NULL; + buf->page_len = 0; + buf->flags = 0; + buf->len = 0; + buf->buflen = PAGE_SIZE; +} + +static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags) +{ + struct page *page; + /* Preallocate one XDR receive buffer */ + page = alloc_page(gfp_flags); + if (page == NULL) + return -ENOMEM; + xdr_buf_init(buf, page_address(page), PAGE_SIZE); + return 0; +} + +static struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt) +{ + gfp_t gfp_flags = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN; + struct rpc_rqst *req; + + /* Pre-allocate one backchannel rpc_rqst */ + req = kzalloc(sizeof(*req), gfp_flags); + if (req == NULL) + return NULL; + + req->rq_xprt = xprt; + INIT_LIST_HEAD(&req->rq_bc_list); + + /* Preallocate one XDR receive buffer */ + if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) { + printk(KERN_ERR "Failed to create bc receive xbuf\n"); + goto out_free; + } + req->rq_rcv_buf.len = PAGE_SIZE; + + /* Preallocate one XDR send buffer */ + if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) { + printk(KERN_ERR "Failed to create bc snd xbuf\n"); + goto out_free; + } + return req; +out_free: + xprt_free_allocation(req); + return NULL; +} + +/* + * Preallocate up to min_reqs structures and related buffers for use + * by the backchannel. This function can be called multiple times + * when creating new sessions that use the same rpc_xprt. The + * preallocated buffers are added to the pool of resources used by + * the rpc_xprt. Any one of these resources may be used by an + * incoming callback request. It's up to the higher levels in the + * stack to enforce that the maximum number of session slots is not + * being exceeded. + * + * Some callback arguments can be large. For example, a pNFS server + * using multiple deviceids. The list can be unbound, but the client + * has the ability to tell the server the maximum size of the callback + * requests. Each deviceID is 16 bytes, so allocate one page + * for the arguments to have enough room to receive a number of these + * deviceIDs. The NFS client indicates to the pNFS server that its + * callback requests can be up to 4096 bytes in size. + */ +int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs) +{ + if (!xprt->ops->bc_setup) + return 0; + return xprt->ops->bc_setup(xprt, min_reqs); +} +EXPORT_SYMBOL_GPL(xprt_setup_backchannel); + +int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs) +{ + struct rpc_rqst *req; + struct list_head tmp_list; + int i; + + dprintk("RPC: setup backchannel transport\n"); + + if (min_reqs > BC_MAX_SLOTS) + min_reqs = BC_MAX_SLOTS; + + /* + * We use a temporary list to keep track of the preallocated + * buffers. Once we're done building the list we splice it + * into the backchannel preallocation list off of the rpc_xprt + * struct. This helps minimize the amount of time the list + * lock is held on the rpc_xprt struct. It also makes cleanup + * easier in case of memory allocation errors. + */ + INIT_LIST_HEAD(&tmp_list); + for (i = 0; i < min_reqs; i++) { + /* Pre-allocate one backchannel rpc_rqst */ + req = xprt_alloc_bc_req(xprt); + if (req == NULL) { + printk(KERN_ERR "Failed to create bc rpc_rqst\n"); + goto out_free; + } + + /* Add the allocated buffer to the tmp list */ + dprintk("RPC: adding req= %p\n", req); + list_add(&req->rq_bc_pa_list, &tmp_list); + } + + /* + * Add the temporary list to the backchannel preallocation list + */ + spin_lock(&xprt->bc_pa_lock); + list_splice(&tmp_list, &xprt->bc_pa_list); + xprt->bc_alloc_count += min_reqs; + xprt->bc_alloc_max += min_reqs; + atomic_add(min_reqs, &xprt->bc_slot_count); + spin_unlock(&xprt->bc_pa_lock); + + dprintk("RPC: setup backchannel transport done\n"); + return 0; + +out_free: + /* + * Memory allocation failed, free the temporary list + */ + while (!list_empty(&tmp_list)) { + req = list_first_entry(&tmp_list, + struct rpc_rqst, + rq_bc_pa_list); + list_del(&req->rq_bc_pa_list); + xprt_free_allocation(req); + } + + dprintk("RPC: setup backchannel transport failed\n"); + return -ENOMEM; +} + +/** + * xprt_destroy_backchannel - Destroys the backchannel preallocated structures. + * @xprt: the transport holding the preallocated strucures + * @max_reqs: the maximum number of preallocated structures to destroy + * + * Since these structures may have been allocated by multiple calls + * to xprt_setup_backchannel, we only destroy up to the maximum number + * of reqs specified by the caller. + */ +void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs) +{ + if (xprt->ops->bc_destroy) + xprt->ops->bc_destroy(xprt, max_reqs); +} +EXPORT_SYMBOL_GPL(xprt_destroy_backchannel); + +void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs) +{ + struct rpc_rqst *req = NULL, *tmp = NULL; + + dprintk("RPC: destroy backchannel transport\n"); + + if (max_reqs == 0) + goto out; + + spin_lock_bh(&xprt->bc_pa_lock); + xprt->bc_alloc_max -= min(max_reqs, xprt->bc_alloc_max); + list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { + dprintk("RPC: req=%p\n", req); + list_del(&req->rq_bc_pa_list); + xprt_free_allocation(req); + xprt->bc_alloc_count--; + atomic_dec(&xprt->bc_slot_count); + if (--max_reqs == 0) + break; + } + spin_unlock_bh(&xprt->bc_pa_lock); + +out: + dprintk("RPC: backchannel list empty= %s\n", + list_empty(&xprt->bc_pa_list) ? "true" : "false"); +} + +static struct rpc_rqst *xprt_get_bc_request(struct rpc_xprt *xprt, __be32 xid, + struct rpc_rqst *new) +{ + struct rpc_rqst *req = NULL; + + dprintk("RPC: allocate a backchannel request\n"); + if (list_empty(&xprt->bc_pa_list)) { + if (!new) + goto not_found; + if (atomic_read(&xprt->bc_slot_count) >= BC_MAX_SLOTS) + goto not_found; + list_add_tail(&new->rq_bc_pa_list, &xprt->bc_pa_list); + xprt->bc_alloc_count++; + atomic_inc(&xprt->bc_slot_count); + } + req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst, + rq_bc_pa_list); + req->rq_reply_bytes_recvd = 0; + memcpy(&req->rq_private_buf, &req->rq_rcv_buf, + sizeof(req->rq_private_buf)); + req->rq_xid = xid; + req->rq_connect_cookie = xprt->connect_cookie; + dprintk("RPC: backchannel req=%p\n", req); +not_found: + return req; +} + +/* + * Return the preallocated rpc_rqst structure and XDR buffers + * associated with this rpc_task. + */ +void xprt_free_bc_request(struct rpc_rqst *req) +{ + struct rpc_xprt *xprt = req->rq_xprt; + + xprt->ops->bc_free_rqst(req); +} + +void xprt_free_bc_rqst(struct rpc_rqst *req) +{ + struct rpc_xprt *xprt = req->rq_xprt; + + dprintk("RPC: free backchannel req=%p\n", req); + + req->rq_connect_cookie = xprt->connect_cookie - 1; + smp_mb__before_atomic(); + clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); + smp_mb__after_atomic(); + + /* + * Return it to the list of preallocations so that it + * may be reused by a new callback request. + */ + spin_lock_bh(&xprt->bc_pa_lock); + if (xprt_need_to_requeue(xprt)) { + xprt_bc_reinit_xdr_buf(&req->rq_snd_buf); + xprt_bc_reinit_xdr_buf(&req->rq_rcv_buf); + req->rq_rcv_buf.len = PAGE_SIZE; + list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list); + xprt->bc_alloc_count++; + atomic_inc(&xprt->bc_slot_count); + req = NULL; + } + spin_unlock_bh(&xprt->bc_pa_lock); + if (req != NULL) { + /* + * The last remaining session was destroyed while this + * entry was in use. Free the entry and don't attempt + * to add back to the list because there is no need to + * have anymore preallocated entries. + */ + dprintk("RPC: Last session removed req=%p\n", req); + xprt_free_allocation(req); + } + xprt_put(xprt); +} + +/* + * One or more rpc_rqst structure have been preallocated during the + * backchannel setup. Buffer space for the send and private XDR buffers + * has been preallocated as well. Use xprt_alloc_bc_request to allocate + * to this request. Use xprt_free_bc_request to return it. + * + * We know that we're called in soft interrupt context, grab the spin_lock + * since there is no need to grab the bottom half spin_lock. + * + * Return an available rpc_rqst, otherwise NULL if non are available. + */ +struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid) +{ + struct rpc_rqst *req, *new = NULL; + + do { + spin_lock(&xprt->bc_pa_lock); + list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) { + if (req->rq_connect_cookie != xprt->connect_cookie) + continue; + if (req->rq_xid == xid) + goto found; + } + req = xprt_get_bc_request(xprt, xid, new); +found: + spin_unlock(&xprt->bc_pa_lock); + if (new) { + if (req != new) + xprt_free_allocation(new); + break; + } else if (req) + break; + new = xprt_alloc_bc_req(xprt); + } while (new); + return req; +} + +/* + * Add callback request to callback list. The callback + * service sleeps on the sv_cb_waitq waiting for new + * requests. Wake it up after adding enqueing the + * request. + */ +void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied) +{ + struct rpc_xprt *xprt = req->rq_xprt; + struct svc_serv *bc_serv = xprt->bc_serv; + + spin_lock(&xprt->bc_pa_lock); + list_del(&req->rq_bc_pa_list); + xprt->bc_alloc_count--; + spin_unlock(&xprt->bc_pa_lock); + + req->rq_private_buf.len = copied; + set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); + + dprintk("RPC: add callback request to list\n"); + xprt_get(xprt); + spin_lock(&bc_serv->sv_cb_lock); + list_add(&req->rq_bc_list, &bc_serv->sv_cb_list); + wake_up(&bc_serv->sv_cb_waitq); + spin_unlock(&bc_serv->sv_cb_lock); +} |