Commit 935c6912 authored by David Howells's avatar David Howells Committed by Al Viro

ipc: Convert mqueue fs to fs_context

Convert the mqueue filesystem to use the filesystem context stuff.

Notes:

 (1) The relevant ipc namespace is selected in when the context is
     initialised (and it defaults to the current task's ipc namespace).
     The caller can override this before calling vfs_get_tree().

 (2) Rather than simply calling kern_mount_data(), mq_init_ns() and
     mq_internal_mount() create a context, adjust it and then do the rest
     of the mount procedure.

 (3) The lazy mqueue mounting on creation of a new namespace is retained
     from a previous patch, but the avoidance of sget() if no superblock
     yet exists is reverted and the superblock is again keyed on the
     namespace pointer.

     Yes, there was a performance gain in not searching the superblock
     hash, but it's only paid once per ipc namespace - and only if someone
     uses mqueue within that namespace, so I'm not sure it's worth it,
     especially as calling sget() allows avoidance of recursion.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 66f592e2
...@@ -18,6 +18,7 @@ ...@@ -18,6 +18,7 @@
#include <linux/pagemap.h> #include <linux/pagemap.h>
#include <linux/file.h> #include <linux/file.h>
#include <linux/mount.h> #include <linux/mount.h>
#include <linux/fs_context.h>
#include <linux/namei.h> #include <linux/namei.h>
#include <linux/sysctl.h> #include <linux/sysctl.h>
#include <linux/poll.h> #include <linux/poll.h>
...@@ -42,6 +43,10 @@ ...@@ -42,6 +43,10 @@
#include <net/sock.h> #include <net/sock.h>
#include "util.h" #include "util.h"
struct mqueue_fs_context {
struct ipc_namespace *ipc_ns;
};
#define MQUEUE_MAGIC 0x19800202 #define MQUEUE_MAGIC 0x19800202
#define DIRENT_SIZE 20 #define DIRENT_SIZE 20
#define FILENT_SIZE 80 #define FILENT_SIZE 80
...@@ -87,9 +92,11 @@ struct mqueue_inode_info { ...@@ -87,9 +92,11 @@ struct mqueue_inode_info {
unsigned long qsize; /* size of queue in memory (sum of all msgs) */ 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 inode_operations mqueue_dir_inode_operations;
static const struct file_operations mqueue_file_operations; static const struct file_operations mqueue_file_operations;
static const struct super_operations mqueue_super_ops; 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 void remove_notification(struct mqueue_inode_info *info);
static struct kmem_cache *mqueue_inode_cachep; static struct kmem_cache *mqueue_inode_cachep;
...@@ -322,7 +329,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb, ...@@ -322,7 +329,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
return ERR_PTR(ret); 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 inode *inode;
struct ipc_namespace *ns = sb->s_fs_info; 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) ...@@ -343,18 +350,56 @@ static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
return 0; return 0;
} }
static struct dentry *mqueue_mount(struct file_system_type *fs_type, static int mqueue_get_tree(struct fs_context *fc)
int flags, const char *dev_name,
void *data)
{ {
struct ipc_namespace *ns; struct mqueue_fs_context *ctx = fc->fs_private;
if (flags & SB_KERNMOUNT) {
ns = data; put_user_ns(fc->user_ns);
data = NULL; fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
} else { fc->s_fs_info = ctx->ipc_ns;
ns = current->nsproxy->ipc_ns; return vfs_get_super(fc, vfs_get_keyed_super, mqueue_fill_super);
} }
return mount_ns(fs_type, flags, data, ns, ns->user_ns, 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) static void init_once(void *foo)
...@@ -1522,15 +1567,22 @@ static const struct super_operations mqueue_super_ops = { ...@@ -1522,15 +1567,22 @@ static const struct super_operations mqueue_super_ops = {
.statfs = simple_statfs, .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 = { static struct file_system_type mqueue_fs_type = {
.name = "mqueue", .name = "mqueue",
.mount = mqueue_mount, .init_fs_context = mqueue_init_fs_context,
.kill_sb = kill_litter_super, .kill_sb = kill_litter_super,
.fs_flags = FS_USERNS_MOUNT, .fs_flags = FS_USERNS_MOUNT,
}; };
int mq_init_ns(struct ipc_namespace *ns) int mq_init_ns(struct ipc_namespace *ns)
{ {
struct vfsmount *m;
ns->mq_queues_count = 0; ns->mq_queues_count = 0;
ns->mq_queues_max = DFLT_QUEUESMAX; ns->mq_queues_max = DFLT_QUEUESMAX;
ns->mq_msg_max = DFLT_MSGMAX; ns->mq_msg_max = DFLT_MSGMAX;
...@@ -1538,12 +1590,10 @@ int mq_init_ns(struct ipc_namespace *ns) ...@@ -1538,12 +1590,10 @@ int mq_init_ns(struct ipc_namespace *ns)
ns->mq_msg_default = DFLT_MSG; ns->mq_msg_default = DFLT_MSG;
ns->mq_msgsize_default = DFLT_MSGSIZE; ns->mq_msgsize_default = DFLT_MSGSIZE;
ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); m = mq_create_mount(ns);
if (IS_ERR(ns->mq_mnt)) { if (IS_ERR(m))
int err = PTR_ERR(ns->mq_mnt); return PTR_ERR(m);
ns->mq_mnt = NULL; ns->mq_mnt = m;
return err;
}
return 0; return 0;
} }
......
...@@ -42,7 +42,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns, ...@@ -42,7 +42,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
goto fail; goto fail;
err = -ENOMEM; err = -ENOMEM;
ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL); ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
if (ns == NULL) if (ns == NULL)
goto fail_dec; goto fail_dec;
......
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