fs: get_acl() must be allowed to return EOPNOTSUPP

posix_acl_xattr_get requires get_acl() to return EOPNOTSUPP if the
filesystem cannot support acls. This is needed for NFS, which can't
know whether or not the server supports acls until it tries to get/set
one.
This patch converts posix_acl_chmod and posix_acl_create to deal with
EOPNOTSUPP return values from get_acl().

Reported-by: Russell King <linux@arm.linux.org.uk>
Link: http://lkml.kernel.org/r/20140130140834.GW15937@n2100.arm.linux.org.uk
Cc: Al Viro viro@zeniv.linux.org.uk>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 38bae5a..11c54fd 100644 (file)
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -521,8 +521,11 @@ posix_acl_chmod(struct inode *inode, umode_t mode)
                return -EOPNOTSUPP;
 
        acl = get_acl(inode, ACL_TYPE_ACCESS);
-       if (IS_ERR_OR_NULL(acl))
+       if (IS_ERR_OR_NULL(acl)) {
+               if (acl == ERR_PTR(-EOPNOTSUPP))
+                       return 0;
                return PTR_ERR(acl);
+       }
 
        ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
        if (ret)
@@ -544,14 +547,15 @@ posix_acl_create(struct inode *dir, umode_t *mode,
                goto no_acl;
 
        p = get_acl(dir, ACL_TYPE_DEFAULT);
-       if (IS_ERR(p))
+       if (IS_ERR(p)) {
+               if (p == ERR_PTR(-EOPNOTSUPP))
+                       goto apply_umask;
                return PTR_ERR(p);
-
-       if (!p) {
-               *mode &= ~current_umask();
-               goto no_acl;
        }
 
+       if (!p)
+               goto apply_umask;
+
        *acl = posix_acl_clone(p, GFP_NOFS);
        if (!*acl)
                return -ENOMEM;
@@ -575,6 +579,8 @@ posix_acl_create(struct inode *dir, umode_t *mode,
        }
        return 0;
 
+apply_umask:
+       *mode &= ~current_umask();
 no_acl:
        *default_acl = NULL;
        *acl = NULL;