Commit 2b82f190 authored by Trond Myklebust's avatar Trond Myklebust Committed by Linus Torvalds
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NFS: Fix race in nfs_set_page_dirty 



Protect nfs_set_page_dirty() against races with nfs_inode_add_request.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 612c9384

fs/nfs/write.c

+14 −3
Original line number Diff line number Diff line
@@ -388,6 +388,8 @@ static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req) 
	}

	SetPagePrivate(req->wb_page);

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

	if (PageDirty(req->wb_page))

		set_bit(PG_NEED_FLUSH, &req->wb_flags);

	nfsi->npages++;

	atomic_inc(&req->wb_count);

	return 0;
@@ -407,6 +409,8 @@ static void nfs_inode_remove_request(struct nfs_page *req) 
	set_page_private(req->wb_page, 0);

	ClearPagePrivate(req->wb_page);

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

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

		__set_page_dirty_nobuffers(req->wb_page);

	nfsi->npages--;

	if (!nfsi->npages) {

		spin_unlock(&nfsi->req_lock);
@@ -1527,15 +1531,22 @@ int nfs_wb_page(struct inode *inode, struct page* page) 


int nfs_set_page_dirty(struct page *page)

{

	spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;

	struct nfs_page *req;

	int ret;



	req = nfs_page_find_request(page);

	spin_lock(req_lock);

	req = nfs_page_find_request_locked(page);

	if (req != NULL) {

		/* Mark any existing write requests for flushing */

		set_bit(PG_NEED_FLUSH, &req->wb_flags);

		ret = !test_and_set_bit(PG_NEED_FLUSH, &req->wb_flags);

		spin_unlock(req_lock);

		nfs_release_request(req);

		return ret;

	}

	return __set_page_dirty_nobuffers(page);

	ret = __set_page_dirty_nobuffers(page);

	spin_unlock(req_lock);

	return ret;

}