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Commit 85710a83 authored by Weston Andros Adamson's avatar Weston Andros Adamson Committed by Trond Myklebust
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nfs: nfs_page should take a ref on the head req 



nfs_pages that aren't the the head of a group must take a reference on the
head as long as ->wb_head is set to it. This stops the head from hitting
a refcount of 0 while there is still an active nfs_page for the page group.

This avoids kref warnings in the writeback code when the page group head
is found and referenced.

Signed-off-by: default avatarWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 17089a29

fs/nfs/pagelist.c

+10 −0
Original line number Diff line number Diff line
@@ -239,15 +239,21 @@ nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev) 
	WARN_ON_ONCE(prev == req);



	if (!prev) {

		/* a head request */

		req->wb_head = req;

		req->wb_this_page = req;

	} else {

		/* a subrequest */

		WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);

		WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));

		req->wb_head = prev->wb_head;

		req->wb_this_page = prev->wb_this_page;

		prev->wb_this_page = req;



		/* All subrequests take a ref on the head request until

		 * nfs_page_group_destroy is called */

		kref_get(&req->wb_head->wb_kref);



		/* grab extra ref if head request has extra ref from

		 * the write/commit path to handle handoff between write

		 * and commit lists */
@@ -271,6 +277,10 @@ nfs_page_group_destroy(struct kref *kref) 
	struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);

	struct nfs_page *tmp, *next;



	/* subrequests must release the ref on the head request */

	if (req->wb_head != req)

		nfs_release_request(req->wb_head);



	if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))

		return;