From 6e15fb6cb6ac678786e98f673ac5ba1bc33e319b Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 29 Mar 2021 16:46:05 -0400 Subject: [PATCH] NFS: Deal correctly with attribute generation counter overflow [ Upstream commit 9fdbfad1777cb4638f489eeb62d85432010c0031 ] We need to use unsigned long subtraction and then convert to signed in order to deal correcly with C overflow rules. Fixes: f5062003465c ("NFS: Set an attribute barrier on all updates") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- fs/nfs/inode.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 6c0035761d17..7a94f5a5f8c8 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -1469,10 +1469,10 @@ EXPORT_SYMBOL_GPL(_nfs_display_fhandle); */ static int nfs_inode_attrs_need_update(const struct inode *inode, const struct nfs_fattr *fattr) { - const struct nfs_inode *nfsi = NFS_I(inode); + unsigned long attr_gencount = NFS_I(inode)->attr_gencount; - return ((long)fattr->gencount - (long)nfsi->attr_gencount) > 0 || - ((long)nfsi->attr_gencount - (long)nfs_read_attr_generation_counter() > 0); + return (long)(fattr->gencount - attr_gencount) > 0 || + (long)(attr_gencount - nfs_read_attr_generation_counter()) > 0; } static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr) @@ -1882,7 +1882,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr) nfsi->attrtimeo_timestamp = now; } /* Set the barrier to be more recent than this fattr */ - if ((long)fattr->gencount - (long)nfsi->attr_gencount > 0) + if ((long)(fattr->gencount - nfsi->attr_gencount) > 0) nfsi->attr_gencount = fattr->gencount; } -- 2.20.1