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authorDavid Howells <dhowells@redhat.com>2018-11-01 23:07:25 +0000
committerAl Viro <viro@zeniv.linux.org.uk>2019-02-28 03:29:29 -0500
commit935c6912b198f60a812b7dada21027b5aac7c461 (patch)
treeb948022b6e597e4e108d773fd9ceeea2985965d6 /ipc
parent66f592e2ece0389c018d74d1bbb2d0b9738cfe48 (diff)
downloadlinux-stericsson-935c6912b198f60a812b7dada21027b5aac7c461.tar.gz
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: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/mqueue.c94
-rw-r--r--ipc/namespace.c2
2 files changed, 73 insertions, 23 deletions
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index c595bed7bfcb..2a9a8be49f5b 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;