Cleanup macros for distinguishing mandatory locks

The combination of S_ISGID bit set and S_IXGRP bit unset is used to mark the
inode as "mandatory lockable" and there's a macro for this check called
MANDATORY_LOCK(inode).  However, fs/locks.c and some filesystems still perform
the explicit i_mode checking.  Besides, Andrew pointed out, that this macro is
buggy itself, as it dereferences the inode arg twice.

Convert this macro into static inline function and switch its users to it,
making the code shorter and more readable.

The __mandatory_lock() helper is to be used in places where the IS_MANDLOCK()
for superblock is already known to be true.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 4 insertions, 10 deletions

diff --git a/fs/locks.c b/fs/locks.c
index 43dbc7f566fa..9a3fe0d8285b 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1119,7 +1119,7 @@ int locks_mandatory_area(int read_write, struct inode *inode,
                          * If we've been sleeping someone might have
                          * changed the permissions behind our back.
                          */
-                        if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
+                        if (__mandatory_lock(inode))
                                 continue;
                 }
 
@@ -1761,9 +1761,7 @@ int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
         /* Don't allow mandatory locks on files that may be memory mapped
          * and shared.
          */
-        if (IS_MANDLOCK(inode) &&
-            (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
-            mapping_writably_mapped(filp->f_mapping)) {
+        if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
                 error = -EAGAIN;
                 goto out;
         }
@@ -1887,9 +1885,7 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
         /* Don't allow mandatory locks on files that may be memory mapped
          * and shared.
          */
-        if (IS_MANDLOCK(inode) &&
-            (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
-            mapping_writably_mapped(filp->f_mapping)) {
+        if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
                 error = -EAGAIN;
                 goto out;
         }
@@ -2083,9 +2079,7 @@ static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx)
                 out += sprintf(out, "%6s %s ",
                              (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
                              (inode == NULL) ? "*NOINODE*" :
-                             (IS_MANDLOCK(inode) &&
-                              (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ?
-                             "MANDATORY" : "ADVISORY ");
+                             mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
         } else if (IS_FLOCK(fl)) {
                 if (fl->fl_type & LOCK_MAND) {
                         out += sprintf(out, "FLOCK  MSNFS     ");