Commit 20633f04 authored by Weston Andros Adamson's avatar Weston Andros Adamson Committed by Trond Myklebust
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nfs: page group syncing in write path 



Operations that modify state for a whole page must be syncronized across
all requests within a page group. In the write path, this is calling
end_page_writeback and removing the head request from an inode.
Both of these operations should not be called until all requests
in a page group have reached the point where they would call them.

This patch should have no effect yet since all page groups currently
have one request, but will come into play when pg_test functions are
modified to split pages into sub-page regions.

Signed-off-by: default avatarWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 67d0338e

fs/nfs/pagelist.c

+2 −0
Original line number Diff line number Diff line
@@ -397,6 +397,8 @@ static void nfs_free_request(struct nfs_page *req) 
	WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));

	WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));

	WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));

	WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));

	WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));



	/* Release struct file and open context */

	nfs_clear_request(req);

fs/nfs/write.c

+20 −12
Original line number Diff line number Diff line
@@ -201,12 +201,15 @@ static void nfs_set_page_writeback(struct page *page) 
	}

}



static void nfs_end_page_writeback(struct page *page)

static void nfs_end_page_writeback(struct nfs_page *req)

{

	struct inode *inode = page_file_mapping(page)->host;

	struct inode *inode = page_file_mapping(req->wb_page)->host;

	struct nfs_server *nfss = NFS_SERVER(inode);



	end_page_writeback(page);

	if (!nfs_page_group_sync_on_bit(req, PG_WB_END))

		return;



	end_page_writeback(req->wb_page);

	if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)

		clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);

}
@@ -397,15 +400,20 @@ static void nfs_inode_remove_request(struct nfs_page *req) 
{

	struct inode *inode = req->wb_context->dentry->d_inode;

	struct nfs_inode *nfsi = NFS_I(inode);

	struct nfs_page *head;



	if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {

		head = req->wb_head;



		spin_lock(&inode->i_lock);

	if (likely(!PageSwapCache(req->wb_page))) {

		set_page_private(req->wb_page, 0);

		ClearPagePrivate(req->wb_page);

		clear_bit(PG_MAPPED, &req->wb_flags);

		if (likely(!PageSwapCache(head->wb_page))) {

			set_page_private(head->wb_page, 0);

			ClearPagePrivate(head->wb_page);

			clear_bit(PG_MAPPED, &head->wb_flags);

		}

		nfsi->npages--;

		spin_unlock(&inode->i_lock);

	}

	nfs_release_request(req);

}
@@ -599,7 +607,7 @@ remove_req: 
		nfs_inode_remove_request(req);

next:

		nfs_unlock_request(req);

		nfs_end_page_writeback(req->wb_page);

		nfs_end_page_writeback(req);

		do_destroy = !test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags);

		nfs_release_request(req);

	}
@@ -964,7 +972,7 @@ static void nfs_redirty_request(struct nfs_page *req) 
{

	nfs_mark_request_dirty(req);

	nfs_unlock_request(req);

	nfs_end_page_writeback(req->wb_page);

	nfs_end_page_writeback(req);

	nfs_release_request(req);

}

include/linux/nfs_page.h

+2 −0
Original line number Diff line number Diff line
@@ -31,6 +31,8 @@ enum { 
	PG_TEARDOWN,		/* page group sync for destroy */

	PG_UNLOCKPAGE,		/* page group sync bit in read path */

	PG_UPTODATE,		/* page group sync bit in read path */

	PG_WB_END,		/* page group sync bit in write path */

	PG_REMOVE,		/* page group sync bit in write path */

};



struct nfs_inode;

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