OpenCloudOS-Kernel/net/sunrpc/backchannel_rqst.c

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nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
/******************************************************************************
(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 cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 16:04:11 +08:00
#include <linux/slab.h>
nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
#include <linux/sunrpc/xprt.h>
#include <linux/export.h>
#include <linux/sunrpc/bc_xprt.h>
nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
#ifdef RPC_DEBUG
#define RPCDBG_FACILITY RPCDBG_TRANS
#endif
/*
* 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_GPL(xprt_setup_backchannel);
nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
/*
* 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_GPL(xprt_destroy_backchannel);
nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
/*
* 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.
*
nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
* 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);
nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
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);
nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
if (req != NULL) {
set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
req->rq_reply_bytes_recvd = 0;
nfs41: New backchannel helper routines This patch introduces support to setup the callback xprt on the client side. It allocates/ destroys the preallocated memory structures used to process backchannel requests. At setup time, xprt_setup_backchannel() is invoked to allocate one or more rpc_rqst structures and substructures. This ensures that they are available when an RPC callback arrives. The rpc_rqst structures are maintained in a linked list attached to the rpc_xprt structure. We keep track of the number of allocations so that they can be correctly removed when the channel is destroyed. When an RPC callback arrives, xprt_alloc_bc_request() is invoked to obtain a preallocated rpc_rqst structure. An rpc_xprt structure is returned, and its RPC_BC_PREALLOC_IN_USE bit is set in rpc_xprt->bc_flags. The structure is removed from the the list since it is now in use, and it will be later added back when its user is done with it. After the RPC callback replies, the rpc_rqst structure is returned by invoking xprt_free_bc_request(). This clears the RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it to be reused by a subsequent RPC callback request. To be consistent with the reception of RPC messages, the backchannel requests should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn copied to the 'struct rpc_rqst' rq_private_buf. [nfs41: Preallocate rpc_rqst receive buffer for handling callbacks] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Update copyright notice and explain page allocation] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:00 +08:00
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);
}