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Commit 7d6ddf88 authored by Benjamin Coddington's avatar Benjamin Coddington Committed by Trond Myklebust
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NFS: Add an iocounter wait function for async RPC tasks 



By sleeping on a new NFS Unlock-On-Close waitqueue, rpc tasks may wait for
a lock context's iocounter to reach zero.  The rpc waitqueue is only woken
when the open_context has the NFS_CONTEXT_UNLOCK flag set in order to
mitigate spurious wake-ups for any iocounter reaching zero.

Signed-off-by: default avatarBenjamin Coddington <bcodding@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 50f2112c

fs/nfs/client.c

+1 −0
Original line number Diff line number Diff line
@@ -218,6 +218,7 @@ static void nfs_cb_idr_remove_locked(struct nfs_client *clp) 
static void pnfs_init_server(struct nfs_server *server)

{

	rpc_init_wait_queue(&server->roc_rpcwaitq, "pNFS ROC");

	rpc_init_wait_queue(&server->uoc_rpcwaitq, "NFS UOC");

}



#else

fs/nfs/pagelist.c

+33 −1
Original line number Diff line number Diff line
@@ -102,6 +102,35 @@ nfs_iocounter_wait(struct nfs_lock_context *l_ctx) 
			TASK_KILLABLE);

}



/**

 * nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O

 * to complete

 * @task: the rpc_task that should wait

 * @l_ctx: nfs_lock_context with io_counter to check

 *

 * Returns true if there is outstanding I/O to wait on and the

 * task has been put to sleep.

 */

bool

nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)

{

	struct inode *inode = d_inode(l_ctx->open_context->dentry);

	bool ret = false;



	if (atomic_read(&l_ctx->io_count) > 0) {

		rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);

		ret = true;

	}



	if (atomic_read(&l_ctx->io_count) == 0) {

		rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);

		ret = false;

	}



	return ret;

}

EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);



/*

 * nfs_page_group_lock - lock the head of the page group

 * @req - request in group that is to be locked
@@ -385,8 +414,11 @@ static void nfs_clear_request(struct nfs_page *req) 
		req->wb_page = NULL;

	}

	if (l_ctx != NULL) {

		if (atomic_dec_and_test(&l_ctx->io_count))

		if (atomic_dec_and_test(&l_ctx->io_count)) {

			wake_up_atomic_t(&l_ctx->io_count);

			if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))

				rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);

		}

		nfs_put_lock_context(l_ctx);

		req->wb_lock_context = NULL;

	}

include/linux/nfs_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ struct nfs_open_context { 
#define NFS_CONTEXT_ERROR_WRITE		(0)

#define NFS_CONTEXT_RESEND_WRITES	(1)

#define NFS_CONTEXT_BAD			(2)

#define NFS_CONTEXT_UNLOCK	(3)

	int error;



	struct list_head list;

include/linux/nfs_fs_sb.h

+1 −0
Original line number Diff line number Diff line
@@ -222,6 +222,7 @@ struct nfs_server { 
	u32			mountd_version;

	unsigned short		mountd_port;

	unsigned short		mountd_protocol;

	struct rpc_wait_queue	uoc_rpcwaitq;

};



/* Server capabilities */

include/linux/nfs_page.h

+1 −0
Original line number Diff line number Diff line
@@ -141,6 +141,7 @@ extern int nfs_page_group_lock(struct nfs_page *, bool); 
extern void nfs_page_group_lock_wait(struct nfs_page *);

extern void nfs_page_group_unlock(struct nfs_page *);

extern bool nfs_page_group_sync_on_bit(struct nfs_page *, unsigned int);

extern bool nfs_async_iocounter_wait(struct rpc_task *, struct nfs_lock_context *);



/*

 * Lock the page of an asynchronous request