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Commit deb7d638 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Fix a race with PG_private and nfs_release_page() 



We don't need to set PG_private for readahead pages, since they never get
unlocked while I/O is in progress. However there is a small race in
nfs_readpage_release() whereby the page may be unlocked, and have
PG_private set.

Fix is to have PG_private set only for the case of writes...

Also fix a bug in nfs_clear_page_writeback(): Don't attempt to clear the
radix_tree tag if we've already deleted the radix tree entry.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 1dd761e9

fs/nfs/pagelist.c

+5 −5
Original line number Diff line number Diff line
@@ -88,7 +88,6 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode, 
	BUG_ON(PagePrivate(page));

	BUG_ON(!PageLocked(page));

	BUG_ON(page->mapping->host != inode);

	SetPagePrivate(page);

	req->wb_offset  = offset;

	req->wb_pgbase	= offset;

	req->wb_bytes   = count;
@@ -136,9 +135,11 @@ void nfs_clear_page_writeback(struct nfs_page *req) 
{

	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);



	if (req->wb_page != NULL) {

		spin_lock(&nfsi->req_lock);

		radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);

		spin_unlock(&nfsi->req_lock);

	}

	nfs_unlock_request(req);

}
@@ -153,7 +154,6 @@ void nfs_clear_request(struct nfs_page *req) 
{

	struct page *page = req->wb_page;

	if (page != NULL) {

		ClearPagePrivate(page);

		page_cache_release(page);

		req->wb_page = NULL;

	}

fs/nfs/write.c

+2 −0
Original line number Diff line number Diff line
@@ -429,6 +429,7 @@ static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req) 
		if (nfs_have_delegation(inode, FMODE_WRITE))

			nfsi->change_attr++;

	}

	SetPagePrivate(req->wb_page);

	nfsi->npages++;

	atomic_inc(&req->wb_count);

	return 0;
@@ -445,6 +446,7 @@ static void nfs_inode_remove_request(struct nfs_page *req) 
	BUG_ON (!NFS_WBACK_BUSY(req));



	spin_lock(&nfsi->req_lock);

	ClearPagePrivate(req->wb_page);

	radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);

	nfsi->npages--;

	if (!nfsi->npages) {