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: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 647e321..d9e5ee5 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -429,6 +429,7 @@
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 @@
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) {
