vfs: check i_nlink limits in vfs_{mkdir,rename_dir,link}

New field of struct super_block - ->s_max_links.  Maximal allowed
value of ->i_nlink or 0; in the latter case all checks still need
to be done in ->link/->mkdir/->rename instances.  Note that this
limit applies both to directoris and to non-directories.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 69cd5bb640f5..0ab89426ba55 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1459,6 +1459,7 @@ struct super_block {
         u8 s_uuid[16];                          /* UUID */
 
         void                    *s_fs_info;     /* Filesystem private info */
+        unsigned int            s_max_links;
         fmode_t                 s_mode;
 
         /* Granularity of c/m/atime in ns.