Commit bd37d6fc authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFSv4: Convert nfs_lock_and_join_requests() to use nfs_page_find_head_request() 



Hide the locking from nfs_lock_and_join_requests() so that we can
separate out the requirements for swapcache pages.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 7e8a30f8

fs/nfs/write.c

+20 −15
Original line number Diff line number Diff line
@@ -154,6 +154,14 @@ static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error) 
	set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);

}



static struct nfs_page *

nfs_page_private_request(struct page *page)

{

	if (!PagePrivate(page))

		return NULL;

	return (struct nfs_page *)page_private(page);

}



/*

 * nfs_page_find_head_request_locked - find head request associated with @page

 *
@@ -164,11 +172,10 @@ static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error) 
static struct nfs_page *

nfs_page_find_head_request_locked(struct nfs_inode *nfsi, struct page *page)

{

	struct nfs_page *req = NULL;

	struct nfs_page *req;



	if (PagePrivate(page))

		req = (struct nfs_page *)page_private(page);

	else if (unlikely(PageSwapCache(page)))

	req = nfs_page_private_request(page);

	if (!req && unlikely(PageSwapCache(page)))

		req = nfs_page_search_commits_for_head_request_locked(nfsi,

			page);
@@ -448,31 +455,29 @@ nfs_lock_and_join_requests(struct page *page) 
	int ret;



try_again:

	if (!(PagePrivate(page) || PageSwapCache(page)))

		return NULL;

	spin_lock(&inode->i_lock);

	/*

	 * A reference is taken only on the head request which acts as a

	 * reference to the whole page group - the group will not be destroyed

	 * until the head reference is released.

	 */

	head = nfs_page_find_head_request_locked(NFS_I(inode), page);



	if (!head) {

		spin_unlock(&inode->i_lock);

	head = nfs_page_find_head_request(page);

	if (!head)

		return NULL;

	}



	/* lock the page head first in order to avoid an ABBA inefficiency */

	if (!nfs_lock_request(head)) {

		spin_unlock(&inode->i_lock);

		ret = nfs_wait_on_request(head);

		nfs_release_request(head);

		if (ret < 0)

			return ERR_PTR(ret);

		goto try_again;

	}

	spin_unlock(&inode->i_lock);



	/* Ensure that nobody removed the request before we locked it */

	if (head != nfs_page_private_request(page) && !PageSwapCache(page)) {

		nfs_unlock_and_release_request(head);

		goto try_again;

	}



	ret = nfs_page_group_lock(head);

	if (ret < 0) {
@@ -559,7 +564,7 @@ nfs_lock_and_join_requests(struct page *page) 
		return NULL;

	}



	/* still holds ref on head from nfs_page_find_head_request_locked

	/* still holds ref on head from nfs_page_find_head_request

	 * and still has lock on head from lock loop */

	return head;

}