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
......@@ -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);
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);
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;
}
......
......@@ -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) {
......
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