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Commit d9156f9f authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Allow the nfs_pageio_descriptor to signal that a re-coalesce is needed 



If an attempt to do pNFS fails, and we have to fall back to writing through
the MDS, then we may want to re-coalesce the requests that we already have
since the block size for the MDS read/writes may be different to that of
the DS read/writes.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent d097971d

fs/nfs/pagelist.c

+54 −3
Original line number Diff line number Diff line
@@ -240,6 +240,7 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc, 
	desc->pg_bsize = bsize;

	desc->pg_base = 0;

	desc->pg_moreio = 0;

	desc->pg_recoalesce = 0;

	desc->pg_inode = inode;

	desc->pg_ops = pg_ops;

	desc->pg_ioflags = io_flags;
@@ -331,7 +332,7 @@ static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc) 
 * Returns true if the request 'req' was successfully coalesced into the

 * existing list of pages 'desc'.

 */

int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,

static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,

			   struct nfs_page *req)

{

	while (!nfs_pageio_do_add_request(desc, req)) {
@@ -340,17 +341,67 @@ int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc, 
		if (desc->pg_error < 0)

			return 0;

		desc->pg_moreio = 0;

		if (desc->pg_recoalesce)

			return 0;

	}

	return 1;

}



static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)

{

	LIST_HEAD(head);



	do {

		list_splice_init(&desc->pg_list, &head);

		desc->pg_bytes_written -= desc->pg_count;

		desc->pg_count = 0;

		desc->pg_base = 0;

		desc->pg_recoalesce = 0;



		while (!list_empty(&head)) {

			struct nfs_page *req;



			req = list_first_entry(&head, struct nfs_page, wb_list);

			nfs_list_remove_request(req);

			if (__nfs_pageio_add_request(desc, req))

				continue;

			if (desc->pg_error < 0)

				return 0;

			break;

		}

	} while (desc->pg_recoalesce);

	return 1;

}



int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,

		struct nfs_page *req)

{

	int ret;



	do {

		ret = __nfs_pageio_add_request(desc, req);

		if (ret)

			break;

		if (desc->pg_error < 0)

			break;

		ret = nfs_do_recoalesce(desc);

	} while (ret);

	return ret;

}



/**

 * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor

 * @desc: pointer to io descriptor

 */

void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)

{

	for (;;) {

		nfs_pageio_doio(desc);

		if (!desc->pg_recoalesce)

			break;

		if (!nfs_do_recoalesce(desc))

			break;

	}

}



/**
@@ -369,7 +420,7 @@ void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index) 
	if (!list_empty(&desc->pg_list)) {

		struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);

		if (index != prev->wb_index + 1)

			nfs_pageio_doio(desc);

			nfs_pageio_complete(desc);

	}

}

include/linux/nfs_page.h

+2 −1
Original line number Diff line number Diff line
@@ -68,7 +68,8 @@ struct nfs_pageio_descriptor { 
	size_t			pg_count;

	size_t			pg_bsize;

	unsigned int		pg_base;

	char			pg_moreio;

	unsigned char		pg_moreio : 1,

				pg_recoalesce : 1;



	struct inode		*pg_inode;

	const struct nfs_pageio_ops *pg_ops;