sysfs: Remove usage of S_BIAS to avoid merge conflict with the vfs tree

In Al's latest vfs tree the code is reworked and S_BIAS has been removed.

It turns out that checking to see if a super block is in the
middle of an unmount in sysfs_exit_ns is unnecessary because we
remove the super_block from the s_supers/s_instances list before
struct sysfs_super_info pointed to by sb->s_fs_info is freed.

For now just delete the unnecessary check to see if a superblock is in the
middle of an unmount, it isn't necessary with or without Al's changes
and it just causes a needless conflict.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 1afa32b..281c0c9 100644 (file)
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -138,6 +138,9 @@ static void sysfs_kill_sb(struct super_block *sb)
 {
        struct sysfs_super_info *info = sysfs_info(sb);
 
+       /* Remove the superblock from fs_supers/s_instances
+        * so we can't find it, before freeing sysfs_super_info.
+        */
        kill_anon_super(sb);
        kfree(info);
 }
@@ -156,9 +159,11 @@ void sysfs_exit_ns(enum kobj_ns_type type, const void *ns)
        spin_lock(&sb_lock);
        list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) {
                struct sysfs_super_info *info = sysfs_info(sb);
-               /* Ignore superblocks that are in the process of unmounting */
-               if (sb->s_count <= S_BIAS)
-                       continue;
+               /*
+                * If we see a superblock on the fs_supers/s_instances
+                * list the unmount has not completed and sb->s_fs_info
+                * points to a valid struct sysfs_super_info.
+                */
                /* Ignore superblocks with the wrong ns */
                if (info->ns[type] != ns)
                        continue;