[RFC][PATCH] simple_set_mnt() should return void

[Sukadev Bhattiprolu]

From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Date: Wed, 28 Jan 2009 17:11:13 -0800
Subject: [RFC][PATCH] simple_set_mnt() should return void

simple_set_mnt() is defined to return int but always returns 0.
Callers assume simple_set_mnt() never fails and don't properly
cleanup if it were to _ever_ fail. For instance, get_sb_single()
and get_sb_nodev() should:

        up_write(sb->s_unmount);
        deactivate_super(sb);

if simple_set_mnt() fails.

Since simple_set_mnt() never fails, would be cleaner if it did
not return anything.

This is a quick rfc patch, tested with only devpts fs.

Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
---
 drivers/mtd/mtdsuper.c |    7 +++++--
 fs/9p/vfs_super.c      |    5 +++--
 fs/cifs/cifsfs.c       |    3 ++-
 fs/devpts/inode.c      |    3 ++-
 fs/libfs.c             |    3 ++-
 fs/namespace.c         |    3 +--
 fs/proc/root.c         |    3 ++-
 fs/super.c             |    9 ++++++---
 fs/ubifs/super.c       |    3 ++-
 include/linux/fs.h     |    2 +-
 kernel/cgroup.c        |    3 ++-
 11 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c
index 00d46e1..92285d0 100644
--- a/drivers/mtd/mtdsuper.c
+++ b/drivers/mtd/mtdsuper.c
@@ -81,13 +81,16 @@ static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
 
 	/* go */
 	sb->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+
+	return 0;
 
 	/* new mountpoint for an already mounted superblock */
 already_mounted:
 	DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
 	      mtd->index, mtd->name);
-	ret = simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	ret = 0;
 	goto out_put;
 
 out_error:
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 93212e4..5f8ab8a 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -168,8 +168,9 @@ static int v9fs_get_sb(struct file_system_type *fs_type, int flags,
 	p9stat_free(st);
 	kfree(st);
 
-P9_DPRINTK(P9_DEBUG_VFS, " return simple set mount\n");
-	return simple_set_mnt(mnt, sb);
+P9_DPRINTK(P9_DEBUG_VFS, " simple set mount, return 0\n");
+	simple_set_mnt(mnt, sb);
+	return 0;
 
 release_sb:
 	if (sb) {
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 13ea532..38491fd 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -606,7 +606,8 @@ cifs_get_sb(struct file_system_type *fs_type,
 		return rc;
 	}
 	sb->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	return 0;
 }
 
 static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 5f3231b..d008105 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -458,7 +458,8 @@ static int get_init_pts_sb(struct file_system_type *fs_type, int flags,
 		s->s_flags |= MS_ACTIVE;
 	}
 	do_remount_sb(s, flags, data, 0);
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 }
 
 /*
diff --git a/fs/libfs.c b/fs/libfs.c
index 49b4409..8e77e11 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -242,7 +242,8 @@ int get_sb_pseudo(struct file_system_type *fs_type, char *name,
 	d_instantiate(dentry, root);
 	s->s_root = dentry;
 	s->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 
 Enomem:
 	up_write(&s->s_umount);
diff --git a/fs/namespace.c b/fs/namespace.c
index 228d8c4..c2594d5 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -397,11 +397,10 @@ static void __mnt_unmake_readonly(struct vfsmount *mnt)
 	spin_unlock(&vfsmount_lock);
 }
 
-int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
+void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
 {
 	mnt->mnt_sb = sb;
 	mnt->mnt_root = dget(sb->s_root);
-	return 0;
 }
 
 EXPORT_SYMBOL(simple_set_mnt);
diff --git a/fs/proc/root.c b/fs/proc/root.c
index f6299a2..1e15a2b 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -83,7 +83,8 @@ static int proc_get_sb(struct file_system_type *fs_type,
 		ns->proc_mnt = mnt;
 	}
 
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	return 0;
 }
 
 static void proc_kill_sb(struct super_block *sb)
diff --git a/fs/super.c b/fs/super.c
index 645e540..17e05f1 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -813,7 +813,8 @@ int get_sb_bdev(struct file_system_type *fs_type,
 		bdev->bd_super = s;
 	}
 
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 
 error_s:
 	error = PTR_ERR(s);
@@ -859,7 +860,8 @@ int get_sb_nodev(struct file_system_type *fs_type,
 		return error;
 	}
 	s->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 }
 
 EXPORT_SYMBOL(get_sb_nodev);
@@ -891,7 +893,8 @@ int get_sb_single(struct file_system_type *fs_type,
 		s->s_flags |= MS_ACTIVE;
 	}
 	do_remount_sb(s, flags, data, 0);
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 }
 
 EXPORT_SYMBOL(get_sb_single);
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 89556ee..cd01c06 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -2032,7 +2032,8 @@ static int ubifs_get_sb(struct file_system_type *fs_type, int flags,
 	/* 'fill_super()' opens ubi again so we must close it here */
 	ubi_close_volume(ubi);
 
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	return 0;
 
 out_deact:
 	up_write(&sb->s_umount);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6022f44..e60b263 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1600,7 +1600,7 @@ struct super_block *sget(struct file_system_type *type,
 extern int get_sb_pseudo(struct file_system_type *, char *,
 	const struct super_operations *ops, unsigned long,
 	struct vfsmount *mnt);
-extern int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb);
+extern void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb);
 int __put_super_and_need_restart(struct super_block *sb);
 
 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c298310..8168d3c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1071,7 +1071,8 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
 		mutex_unlock(&cgroup_mutex);
 	}
 
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	return 0;
 
  free_cg_links:
 	free_cg_links(&tmp_cg_links);
-- 
1.5.2.5

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