Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs mount infrastructure updates from Al Viro:
 "The rest of core infrastructure; no new syscalls in that pile, but the
  old parts are switched to new infrastructure. At that point
  conversions of individual filesystems can happen independently; some
  are done here (afs, cgroup, procfs, etc.), there's also a large series
  outside of that pile dealing with NFS (quite a bit of option-parsing
  stuff is getting used there - it's one of the most convoluted
  filesystems in terms of mount-related logics), but NFS bits are the
  next cycle fodder.

  It got seriously simplified since the last cycle; documentation is
  probably the weakest bit at the moment - I considered dropping the
  commit introducing Documentation/filesystems/mount_api.txt (cutting
  the size increase by quarter ;-), but decided that it would be better
  to fix it up after -rc1 instead.

  That pile allows to do followup work in independent branches, which
  should make life much easier for the next cycle. fs/super.c size
  increase is unpleasant; there's a followup series that allows to
  shrink it considerably, but I decided to leave that until the next
  cycle"

* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits)
  afs: Use fs_context to pass parameters over automount
  afs: Add fs_context support
  vfs: Add some logging to the core users of the fs_context log
  vfs: Implement logging through fs_context
  vfs: Provide documentation for new mount API
  vfs: Remove kern_mount_data()
  hugetlbfs: Convert to fs_context
  cpuset: Use fs_context
  kernfs, sysfs, cgroup, intel_rdt: Support fs_context
  cgroup: store a reference to cgroup_ns into cgroup_fs_context
  cgroup1_get_tree(): separate "get cgroup_root to use" into a separate helper
  cgroup_do_mount(): massage calling conventions
  cgroup: stash cgroup_root reference into cgroup_fs_context
  cgroup2: switch to option-by-option parsing
  cgroup1: switch to option-by-option parsing
  cgroup: take options parsing into ->parse_monolithic()
  cgroup: fold cgroup1_mount() into cgroup1_get_tree()
  cgroup: start switching to fs_context
  ipc: Convert mqueue fs to fs_context
  proc: Add fs_context support to procfs
  ...

2 files changed, 73 insertions, 23 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index c839bf83231d..aea30530c472 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -18,6 +18,7 @@
 #include <linux/pagemap.h>
 #include <linux/file.h>
 #include <linux/mount.h>
+#include <linux/fs_context.h>
 #include <linux/namei.h>
 #include <linux/sysctl.h>
 #include <linux/poll.h>
@@ -42,6 +43,10 @@
 #include <net/sock.h>
 #include "util.h"
 
+struct mqueue_fs_context {
+        struct ipc_namespace    *ipc_ns;
+};
+
 #define MQUEUE_MAGIC    0x19800202
 #define DIRENT_SIZE     20
 #define FILENT_SIZE     80
@@ -87,9 +92,11 @@ struct mqueue_inode_info {
         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
 };
 
+static struct file_system_type mqueue_fs_type;
 static const struct inode_operations mqueue_dir_inode_operations;
 static const struct file_operations mqueue_file_operations;
 static const struct super_operations mqueue_super_ops;
+static const struct fs_context_operations mqueue_fs_context_ops;
 static void remove_notification(struct mqueue_inode_info *info);
 
 static struct kmem_cache *mqueue_inode_cachep;
@@ -322,7 +329,7 @@ err:
         return ERR_PTR(ret);
 }
 
-static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
+static int mqueue_fill_super(struct super_block *sb, struct fs_context *fc)
 {
         struct inode *inode;
         struct ipc_namespace *ns = sb->s_fs_info;
@@ -343,18 +350,56 @@ static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
         return 0;
 }
 
-static struct dentry *mqueue_mount(struct file_system_type *fs_type,
-                         int flags, const char *dev_name,
-                         void *data)
+static int mqueue_get_tree(struct fs_context *fc)
 {
-        struct ipc_namespace *ns;
-        if (flags & SB_KERNMOUNT) {
-                ns = data;
-                data = NULL;
-        } else {
-                ns = current->nsproxy->ipc_ns;
-        }
-        return mount_ns(fs_type, flags, data, ns, ns->user_ns, mqueue_fill_super);
+        struct mqueue_fs_context *ctx = fc->fs_private;
+
+        put_user_ns(fc->user_ns);
+        fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
+        fc->s_fs_info = ctx->ipc_ns;
+        return vfs_get_super(fc, vfs_get_keyed_super, mqueue_fill_super);
+}
+
+static void mqueue_fs_context_free(struct fs_context *fc)
+{
+        struct mqueue_fs_context *ctx = fc->fs_private;
+
+        if (ctx->ipc_ns)
+                put_ipc_ns(ctx->ipc_ns);
+        kfree(ctx);
+}
+
+static int mqueue_init_fs_context(struct fs_context *fc)
+{
+        struct mqueue_fs_context *ctx;
+
+        ctx = kzalloc(sizeof(struct mqueue_fs_context), GFP_KERNEL);
+        if (!ctx)
+                return -ENOMEM;
+
+        ctx->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
+        fc->fs_private = ctx;
+        fc->ops = &mqueue_fs_context_ops;
+        return 0;
+}
+
+static struct vfsmount *mq_create_mount(struct ipc_namespace *ns)
+{
+        struct mqueue_fs_context *ctx;
+        struct fs_context *fc;
+        struct vfsmount *mnt;
+
+        fc = fs_context_for_mount(&mqueue_fs_type, SB_KERNMOUNT);
+        if (IS_ERR(fc))
+                return ERR_CAST(fc);
+
+        ctx = fc->fs_private;
+        put_ipc_ns(ctx->ipc_ns);
+        ctx->ipc_ns = get_ipc_ns(ns);
+
+        mnt = fc_mount(fc);
+        put_fs_context(fc);
+        return mnt;
 }
 
 static void init_once(void *foo)
@@ -1522,15 +1567,22 @@ static const struct super_operations mqueue_super_ops = {
         .statfs = simple_statfs,
 };
 
+static const struct fs_context_operations mqueue_fs_context_ops = {
+        .free           = mqueue_fs_context_free,
+        .get_tree       = mqueue_get_tree,
+};
+
 static struct file_system_type mqueue_fs_type = {
-        .name = "mqueue",
-        .mount = mqueue_mount,
-        .kill_sb = kill_litter_super,
-        .fs_flags = FS_USERNS_MOUNT,
+        .name                   = "mqueue",
+        .init_fs_context        = mqueue_init_fs_context,
+        .kill_sb                = kill_litter_super,
+        .fs_flags               = FS_USERNS_MOUNT,
 };
 
 int mq_init_ns(struct ipc_namespace *ns)
 {
+        struct vfsmount *m;
+
         ns->mq_queues_count  = 0;
         ns->mq_queues_max    = DFLT_QUEUESMAX;
         ns->mq_msg_max       = DFLT_MSGMAX;
@@ -1538,12 +1590,10 @@ int mq_init_ns(struct ipc_namespace *ns)
         ns->mq_msg_default   = DFLT_MSG;
         ns->mq_msgsize_default  = DFLT_MSGSIZE;
 
-        ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
-        if (IS_ERR(ns->mq_mnt)) {
-                int err = PTR_ERR(ns->mq_mnt);
-                ns->mq_mnt = NULL;
-                return err;
-        }
+        m = mq_create_mount(ns);
+        if (IS_ERR(m))
+                return PTR_ERR(m);
+        ns->mq_mnt = m;
         return 0;
 }
 
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 21607791d62c..b3ca1476ca51 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -42,7 +42,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
                 goto fail;
 
         err = -ENOMEM;
-        ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
+        ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
         if (ns == NULL)
                 goto fail_dec;