> On Jul 7, 2016, at 01:53, Oleg Drokin <green@xxxxxxxxxxxxxx> wrote: > > It's great when we can shave an extra RPC, but not at the expense > of correctness. > We should not return EPERM (from vfs_create/mknod/mkdir) if the > name already exists, even if we have no write access in parent. > > Since the check in nfs_permission is clearly not enough to stave > off this, just throw in the extra READ access to actually > go through. > > Signed-off-by: Oleg Drokin <green@xxxxxxxxxxxxxx> > --- > fs/nfs/dir.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c > index d8015a0..8c7835b 100644 > --- a/fs/nfs/dir.c > +++ b/fs/nfs/dir.c > @@ -1383,8 +1383,10 @@ struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned in > /* > * If we're doing an exclusive create, optimize away the lookup > * but don't hash the dentry. > + * This optimization only works if we can write in the parent. > */ > - if (nfs_is_exclusive_create(dir, flags)) > + if (nfs_is_exclusive_create(dir, flags) && > + (inode_permission(dir, MAY_WRITE | MAY_READ | MAY_EXEC) == 0)) > return NULL; > NACK. The only write permission we should care about on the client side is whether or not the filesystem is mounted read-only. All other permissions are checked by the server. Cheers Trond -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
