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Commit fedb595c authored by Chuck Lever's avatar Chuck Lever Committed by Trond Myklebust
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NFS: "open code" the NFS direct write rescheduler 



An NFSv3/v4 client must reschedule on-the-wire writes if the writes are
UNSTABLE, and the server reboots before the client can complete a
subsequent COMMIT request.

To support direct asynchronous scatter-gather writes, the write
rescheduler in fs/nfs/direct.c must not depend on the I/O parameters
in the controlling nfs_direct_req structure.  iovecs can be somewhat
arbitrarily complex, so there could be an unbounded amount of information
to save for a rarely encountered requirement.

Refactor the direct write rescheduler so it uses information from each
nfs_write_data structure to reschedule writes, instead of caching that
information in the controlling nfs_direct_req structure.

Signed-off-by: default avatarChuck Lever <cel@netapp.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent b1c5921c

fs/nfs/direct.c

+43 −8
Original line number Diff line number Diff line
@@ -94,8 +94,8 @@ struct nfs_direct_req { 
	struct nfs_writeverf	verf;		/* unstable write verifier */

};



static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync);

static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);

static const struct rpc_call_ops nfs_write_direct_ops;



static inline void get_dreq(struct nfs_direct_req *dreq)

{
@@ -435,14 +435,51 @@ static void nfs_direct_free_writedata(struct nfs_direct_req *dreq) 
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)

static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)

{

	struct list_head *pos;

	struct inode *inode = dreq->inode;

	struct list_head *p;

	struct nfs_write_data *data;



	list_splice_init(&dreq->rewrite_list, &dreq->list);

	list_for_each(pos, &dreq->list)

		get_dreq(dreq);

	dreq->count = 0;

	get_dreq(dreq);



	list_for_each(p, &dreq->rewrite_list) {

		data = list_entry(p, struct nfs_write_data, pages);



		get_dreq(dreq);



		/*

		 * Reset data->res.

		 */

		nfs_fattr_init(&data->fattr);

		data->res.count = data->args.count;

		memset(&data->verf, 0, sizeof(data->verf));



		/*

		 * Reuse data->task; data->args should not have changed

		 * since the original request was sent.

		 */

		rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,

				&nfs_write_direct_ops, data);

		NFS_PROTO(inode)->write_setup(data, FLUSH_STABLE);



	nfs_direct_write_schedule(dreq, FLUSH_STABLE);

		data->task.tk_priority = RPC_PRIORITY_NORMAL;

		data->task.tk_cookie = (unsigned long) inode;



		/*

		 * We're called via an RPC callback, so BKL is already held.

		 */

		rpc_execute(&data->task);



		dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",

				data->task.tk_pid,

				inode->i_sb->s_id,

				(long long)NFS_FILEID(inode),

				data->args.count,

				(unsigned long long)data->args.offset);

	}



	if (put_dreq(dreq))

		nfs_direct_write_complete(dreq, inode);

}



static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
@@ -612,8 +649,6 @@ static void nfs_direct_write_result(struct rpc_task *task, void *calldata) 
				}

		}

	}

	/* In case we have to resend */

	data->args.stable = NFS_FILE_SYNC;



	spin_unlock(&dreq->lock);

}