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Commit bc0fb201 authored by Chuck Lever's avatar Chuck Lever Committed by Trond Myklebust
Browse files

NFS: create common routine for waiting for direct I/O to complete 



We're about to add asynchrony to the NFS direct write path.  Begin by
abstracting out the common pieces in the read path.

The first piece is nfs_direct_read_wait, which works the same whether the
process is waiting for a read or a write.

Test plan:
Compile kernel with CONFIG_NFS and CONFIG_NFS_DIRECTIO enabled.

Signed-off-by: default avatarChuck Lever <cel@netapp.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 487b8372

fs/nfs/direct.c

+26 −31
Original line number Diff line number Diff line
@@ -158,6 +158,30 @@ static void nfs_direct_req_release(struct kref *kref) 
	kmem_cache_free(nfs_direct_cachep, dreq);

}



/*

 * Collects and returns the final error value/byte-count.

 */

static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)

{

	int result = -EIOCBQUEUED;



	/* Async requests don't wait here */

	if (dreq->iocb)

		goto out;



	result = wait_event_interruptible(dreq->wait,

					(atomic_read(&dreq->complete) == 0));



	if (!result)

		result = atomic_read(&dreq->error);

	if (!result)

		result = atomic_read(&dreq->count);



out:

	kref_put(&dreq->kref, nfs_direct_req_release);

	return (ssize_t) result;

}



/*

 * Note we also set the number of requests we have in the dreq when we are

 * done.  This prevents races with I/O completion so we will always wait
@@ -213,7 +237,7 @@ static struct nfs_direct_req *nfs_direct_read_alloc(size_t nbytes, size_t rsize) 
/*

 * We must hold a reference to all the pages in this direct read request

 * until the RPCs complete.  This could be long *after* we are woken up in

 * nfs_direct_read_wait (for instance, if someone hits ^C on a slow server).

 * nfs_direct_wait (for instance, if someone hits ^C on a slow server).

 *

 * In addition, synchronous I/O uses a stack-allocated iocb.  Thus we

 * can't trust the iocb is still valid here if this is a synchronous
@@ -315,35 +339,6 @@ static void nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long 
	} while (count != 0);

}



/*

 * Collects and returns the final error value/byte-count.

 */

static ssize_t nfs_direct_read_wait(struct nfs_direct_req *dreq, int intr)

{

	int result = -EIOCBQUEUED;



	/* Async requests don't wait here */

 	if (dreq->iocb)

		goto out;



	result = 0;

	if (intr) {

		result = wait_event_interruptible(dreq->wait,

					(atomic_read(&dreq->complete) == 0));

	} else {

		wait_event(dreq->wait, (atomic_read(&dreq->complete) == 0));

	}



	if (!result)

		result = atomic_read(&dreq->error);

	if (!result)

		result = atomic_read(&dreq->count);



out:

	kref_put(&dreq->kref, nfs_direct_req_release);

	return (ssize_t) result;

}



static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t file_offset, struct page **pages, unsigned int nr_pages)

{

	ssize_t result;
@@ -366,7 +361,7 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size 
	nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count);

	rpc_clnt_sigmask(clnt, &oldset);

	nfs_direct_read_schedule(dreq, user_addr, count, file_offset);

	result = nfs_direct_read_wait(dreq, clnt->cl_intr);

	result = nfs_direct_wait(dreq);

	rpc_clnt_sigunmask(clnt, &oldset);



	return result;