On Thu, Jan 04, 2024 at 09:39:04AM +0200, Amir Goldstein wrote: > On Wed, Jan 3, 2024 at 5:19 PM Chuck Lever <cel@xxxxxxxxxx> wrote: > > > > From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> > > > > The fallback implementation for the get_name export operation uses > > readdir() to try to match the inode number to a filename. That filename > > is then used together with lookup_one() to produce a dentry. > > A problem arises when we match the '.' or '..' entries, since that > > causes lookup_one() to fail. This has sometimes been seen to occur for > > filesystems that violate POSIX requirements around uniqueness of inode > > numbers, something that is common for snapshot directories. > > > > This patch just ensures that we skip '.' and '..' rather than allowing a > > match. > > > > Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> > > Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx> > > Acked-by: Amir Goldstein <amir73il@xxxxxxxxx> > > Link: https://lore.kernel.org/linux-nfs/CAOQ4uxiOZobN76OKB-VBNXWeFKVwLW_eK5QtthGyYzWU9mjb7Q@xxxxxxxxxxxxxx/ > > Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> > > --- > > fs/exportfs/expfs.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c > > index 3ae0154c5680..84af58eaf2ca 100644 > > --- a/fs/exportfs/expfs.c > > +++ b/fs/exportfs/expfs.c > > @@ -255,7 +255,9 @@ static bool filldir_one(struct dir_context *ctx, const char *name, int len, > > container_of(ctx, struct getdents_callback, ctx); > > > > buf->sequence++; > > - if (buf->ino == ino && len <= NAME_MAX) { > > + /* Ignore the '.' and '..' entries */ > > + if ((len > 2 || name[0] != '.' || (len == 2 && name[1] != '.')) && > > + buf->ino == ino && len <= NAME_MAX) { > > > Thank you for creating the helper, but if you already went to this trouble, > I think it is better to introduce is_dot_dotdot() as a local helper already > in this backportable patch, so that stable kernel code is same as upstream > code (good for future fixes) and then dedupe the local helper with the rest > of the local helpers in patch 2? There's now no Fixes: nor a Cc: stable on 1/2. You convinced me that 1/2 will not result in any external behavior change. The upshot is I do not expect 1/2 will be backported, unless I have grossly misread your emails. -- Chuck Lever
