NFS: Fix nfs_set_page_dirty()

Be more careful about testing page->mapping.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 7975589..8593965 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1531,10 +1531,18 @@ 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 address_space *mapping = page->mapping;
+       struct inode *inode;
+       spinlock_t *req_lock;
        struct nfs_page *req;
        int ret;
 
+       if (!mapping)
+               goto out_raced;
+       inode = mapping->host;
+       if (!inode)
+               goto out_raced;
+       req_lock = &NFS_I(inode)->req_lock;
        spin_lock(req_lock);
        req = nfs_page_find_request_locked(page);
        if (req != NULL) {
@@ -1547,6 +1555,8 @@ int nfs_set_page_dirty(struct page *page)
        ret = __set_page_dirty_nobuffers(page);
        spin_unlock(req_lock);
        return ret;
+out_raced:
+       return !TestSetPageDirty(page);
 }