diff options
Diffstat (limited to 'net/sunrpc/backchannel_rqst.c')
| -rw-r--r-- | net/sunrpc/backchannel_rqst.c | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c new file mode 100644 index 00000000000..553621fb2c4 --- /dev/null +++ b/net/sunrpc/backchannel_rqst.c @@ -0,0 +1,281 @@ +/****************************************************************************** + +(c) 2007 Network Appliance, Inc. All Rights Reserved. +(c) 2009 NetApp. All Rights Reserved. + +NetApp provides this source code under the GPL v2 License. +The GPL v2 license is available at +http://opensource.org/licenses/gpl-license.php. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR +CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, +EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR +PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF +LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING +NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +******************************************************************************/ + +#include <linux/tcp.h> +#include <linux/sunrpc/xprt.h> + +#ifdef RPC_DEBUG +#define RPCDBG_FACILITY RPCDBG_TRANS +#endif + +#if defined(CONFIG_NFS_V4_1) + +/* + * 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 > 0; +} + +static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n) +{ + xprt->bc_alloc_count += n; +} + +static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n) +{ + return xprt->bc_alloc_count -= n; +} + +/* + * 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); + BUG_ON(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); + xbufp = &req->rq_private_buf; + free_page((unsigned long)xbufp->head[0].iov_base); + xbufp = &req->rq_snd_buf; + free_page((unsigned long)xbufp->head[0].iov_base); + list_del(&req->rq_bc_pa_list); + kfree(req); +} + +/* + * 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. Anyone of these resources may be used 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) +{ + struct page *page_rcv = NULL, *page_snd = NULL; + struct xdr_buf *xbufp = NULL; + struct rpc_rqst *req, *tmp; + struct list_head tmp_list; + int i; + + dprintk("RPC: setup backchannel transport\n"); + + /* + * 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 = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL); + 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); + + req->rq_xprt = xprt; + INIT_LIST_HEAD(&req->rq_list); + INIT_LIST_HEAD(&req->rq_bc_list); + + /* Preallocate one XDR receive buffer */ + page_rcv = alloc_page(GFP_KERNEL); + if (page_rcv == NULL) { + printk(KERN_ERR "Failed to create bc receive xbuf\n"); + goto out_free; + } + xbufp = &req->rq_rcv_buf; + xbufp->head[0].iov_base = page_address(page_rcv); + xbufp->head[0].iov_len = PAGE_SIZE; + xbufp->tail[0].iov_base = NULL; + xbufp->tail[0].iov_len = 0; + xbufp->page_len = 0; + xbufp->len = PAGE_SIZE; + xbufp->buflen = PAGE_SIZE; + + /* Preallocate one XDR send buffer */ + page_snd = alloc_page(GFP_KERNEL); + if (page_snd == NULL) { + printk(KERN_ERR "Failed to create bc snd xbuf\n"); + goto out_free; + } + + xbufp = &req->rq_snd_buf; + xbufp->head[0].iov_base = page_address(page_snd); + xbufp->head[0].iov_len = 0; + xbufp->tail[0].iov_base = NULL; + xbufp->tail[0].iov_len = 0; + xbufp->page_len = 0; + xbufp->len = 0; + xbufp->buflen = PAGE_SIZE; + } + + /* + * Add the temporary list to the backchannel preallocation list + */ + spin_lock_bh(&xprt->bc_pa_lock); + list_splice(&tmp_list, &xprt->bc_pa_list); + xprt_inc_alloc_count(xprt, min_reqs); + spin_unlock_bh(&xprt->bc_pa_lock); + + dprintk("RPC: setup backchannel transport done\n"); + return 0; + +out_free: + /* + * Memory allocation failed, free the temporary list + */ + list_for_each_entry_safe(req, tmp, &tmp_list, rq_bc_pa_list) + xprt_free_allocation(req); + + dprintk("RPC: setup backchannel transport failed\n"); + return -1; +} +EXPORT_SYMBOL(xprt_setup_backchannel); + +/* + * Destroys the backchannel preallocated structures. + * 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. + * @xprt: the transport holding the preallocated strucures + * @max_reqs the maximum number of preallocated structures to destroy + */ +void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs) +{ + struct rpc_rqst *req = NULL, *tmp = NULL; + + dprintk("RPC: destroy backchannel transport\n"); + + BUG_ON(max_reqs == 0); + spin_lock_bh(&xprt->bc_pa_lock); + xprt_dec_alloc_count(xprt, max_reqs); + list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { + dprintk("RPC: req=%p\n", req); + xprt_free_allocation(req); + if (--max_reqs == 0) + break; + } + spin_unlock_bh(&xprt->bc_pa_lock); + + dprintk("RPC: backchannel list empty= %s\n", + list_empty(&xprt->bc_pa_list) ? "true" : "false"); +} +EXPORT_SYMBOL(xprt_destroy_backchannel); + +/* + * 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_alloc_bc_request(struct rpc_xprt *xprt) +{ + struct rpc_rqst *req; + + dprintk("RPC: allocate a backchannel request\n"); + spin_lock(&xprt->bc_pa_lock); + if (!list_empty(&xprt->bc_pa_list)) { + req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst, + rq_bc_pa_list); + list_del(&req->rq_bc_pa_list); + } else { + req = NULL; + } + spin_unlock(&xprt->bc_pa_lock); + + if (req != NULL) { + set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); + req->rq_reply_bytes_recvd = 0; + req->rq_bytes_sent = 0; + memcpy(&req->rq_private_buf, &req->rq_rcv_buf, + sizeof(req->rq_private_buf)); + } + dprintk("RPC: backchannel req=%p\n", req); + 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; + + dprintk("RPC: free backchannel req=%p\n", req); + + smp_mb__before_clear_bit(); + BUG_ON(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); + clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); + smp_mb__after_clear_bit(); + + if (!xprt_need_to_requeue(xprt)) { + /* + * 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); + return; + } + + /* + * 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); + list_add(&req->rq_bc_pa_list, &xprt->bc_pa_list); + spin_unlock_bh(&xprt->bc_pa_lock); +} + +#endif /* CONFIG_NFS_V4_1 */ |