Commit 4b9bb25b authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Switch to using mapping->private_lock for page writeback lookups. 



Switch from using the inode->i_lock for this to avoid contention with
other metadata manipulation.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 5cb953d4

fs/nfs/write.c

+16 −11
Original line number Diff line number Diff line
@@ -172,18 +172,18 @@ nfs_page_private_request(struct page *page) 
static struct nfs_page *

nfs_page_find_private_request(struct page *page)

{

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

	struct address_space *mapping = page_file_mapping(page);

	struct nfs_page *req;



	if (!PagePrivate(page))

		return NULL;

	spin_lock(&inode->i_lock);

	spin_lock(&mapping->private_lock);

	req = nfs_page_private_request(page);

	if (req) {

		WARN_ON_ONCE(req->wb_head != req);

		kref_get(&req->wb_kref);

	}

	spin_unlock(&inode->i_lock);

	spin_unlock(&mapping->private_lock);

	return req;

}
@@ -743,6 +743,7 @@ int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc) 
 */

static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)

{

	struct address_space *mapping = page_file_mapping(req->wb_page);

	struct nfs_inode *nfsi = NFS_I(inode);



	WARN_ON_ONCE(req->wb_this_page != req);
@@ -750,19 +751,23 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req) 
	/* Lock the request! */

	nfs_lock_request(req);



	spin_lock(&inode->i_lock);

	if (!nfs_have_writebacks(inode) &&

	    NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))

		inode->i_version++;

	/*

	 * Swap-space should not get truncated. Hence no need to plug the race

	 * with invalidate/truncate.

	 */

	spin_lock(&mapping->private_lock);

	if (!nfs_have_writebacks(inode) &&

	    NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE)) {

		spin_lock(&inode->i_lock);

		inode->i_version++;

		spin_unlock(&inode->i_lock);

	}

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

		set_bit(PG_MAPPED, &req->wb_flags);

		SetPagePrivate(req->wb_page);

		set_page_private(req->wb_page, (unsigned long)req);

	}

	spin_unlock(&mapping->private_lock);

	atomic_long_inc(&nfsi->nrequests);

	/* this a head request for a page group - mark it as having an

	 * extra reference so sub groups can follow suit.
@@ -770,7 +775,6 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req) 
	 * adding subrequests. */

	WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));

	kref_get(&req->wb_kref);

	spin_unlock(&inode->i_lock);

}



/*
@@ -778,7 +782,8 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req) 
 */

static void nfs_inode_remove_request(struct nfs_page *req)

{

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

	struct address_space *mapping = page_file_mapping(req->wb_page);

	struct inode *inode = mapping->host;

	struct nfs_inode *nfsi = NFS_I(inode);

	struct nfs_page *head;
@@ -786,13 +791,13 @@ static void nfs_inode_remove_request(struct nfs_page *req) 
	if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {

		head = req->wb_head;



		spin_lock(&inode->i_lock);

		spin_lock(&mapping->private_lock);

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

			set_page_private(head->wb_page, 0);

			ClearPagePrivate(head->wb_page);

			clear_bit(PG_MAPPED, &head->wb_flags);

		}

		spin_unlock(&inode->i_lock);

		spin_unlock(&mapping->private_lock);

	}



	if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))