[PATCH] proc: Fix proc_kill_inodes to kill dentries on all proc superblocks

[ebiederm@xmission.com (Eric W. Biederman)]

It appears we overlooked support for removing generic proc files
when we added support for multiple proc super blocks.  Handle
that now.

Since all of the relevant code is already inside of a spin_lock
we can just grab the superblock lock and walk through all of
the instances of proc superblocks.

Heavy weight but it is simple and should work.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/proc/generic.c  |   38 +++++++++++++++++++++-----------------
 fs/proc/internal.h |    2 ++
 fs/proc/root.c     |    2 +-
 3 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 1bdb624..3906770 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -561,28 +561,32 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
 static void proc_kill_inodes(struct proc_dir_entry *de)
 {
 	struct list_head *p;
-	struct super_block *sb = proc_mnt->mnt_sb;
+	struct super_block *sb;
 
 	/*
 	 * Actually it's a partial revoke().
 	 */
-	file_list_lock();
-	list_for_each(p, &sb->s_files) {
-		struct file * filp = list_entry(p, struct file, f_u.fu_list);
-		struct dentry * dentry = filp->f_path.dentry;
-		struct inode * inode;
-		const struct file_operations *fops;
-
-		if (dentry->d_op != &proc_dentry_operations)
-			continue;
-		inode = dentry->d_inode;
-		if (PDE(inode) != de)
-			continue;
-		fops = filp->f_op;
-		filp->f_op = NULL;
-		fops_put(fops);
+	spin_lock(&sb_lock);
+	list_for_each_entry(sb, &proc_fs_type.fs_supers, s_instances) {
+		file_list_lock();
+		list_for_each(p, &sb->s_files) {
+			struct file * filp = list_entry(p, struct file, f_u.fu_list);
+			struct dentry * dentry = filp->f_path.dentry;
+			struct inode * inode;
+			const struct file_operations *fops;
+
+			if (dentry->d_op != &proc_dentry_operations)
+				continue;
+			inode = dentry->d_inode;
+			if (PDE(inode) != de)
+				continue;
+			fops = filp->f_op;
+			filp->f_op = NULL;
+			fops_put(fops);
+		}
+		file_list_unlock();
 	}
-	file_list_unlock();
+	spin_unlock(&sb_lock);
 }
 
 static struct proc_dir_entry *proc_create(struct proc_dir_entry **parent,
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 1820eb2..1b2b6c6 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -78,3 +78,5 @@ static inline int proc_fd(struct inode *inode)
 {
 	return PROC_I(inode)->fd;
 }
+
+extern struct file_system_type proc_fs_type;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index ec9cb3b..1f86bb8 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -98,7 +98,7 @@ static void proc_kill_sb(struct super_block *sb)
 	put_pid_ns(ns);
 }
 
-static struct file_system_type proc_fs_type = {
+struct file_system_type proc_fs_type = {
 	.name		= "proc",
 	.get_sb		= proc_get_sb,
 	.kill_sb	= proc_kill_sb,
-- 
1.5.3.rc6.17.g1911