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>
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66f592e2ec
Коммит
935c6912b1
86
ipc/mqueue.c
86
ipc/mqueue.c
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@ -18,6 +18,7 @@
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#include <linux/pagemap.h>
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#include <linux/file.h>
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#include <linux/mount.h>
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#include <linux/fs_context.h>
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#include <linux/namei.h>
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#include <linux/sysctl.h>
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#include <linux/poll.h>
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@ -42,6 +43,10 @@
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#include <net/sock.h>
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#include "util.h"
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struct mqueue_fs_context {
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struct ipc_namespace *ipc_ns;
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};
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#define MQUEUE_MAGIC 0x19800202
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#define DIRENT_SIZE 20
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#define FILENT_SIZE 80
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@ -87,9 +92,11 @@ struct mqueue_inode_info {
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unsigned long qsize; /* size of queue in memory (sum of all msgs) */
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};
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static struct file_system_type mqueue_fs_type;
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static const struct inode_operations mqueue_dir_inode_operations;
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static const struct file_operations mqueue_file_operations;
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static const struct super_operations mqueue_super_ops;
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static const struct fs_context_operations mqueue_fs_context_ops;
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static void remove_notification(struct mqueue_inode_info *info);
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static struct kmem_cache *mqueue_inode_cachep;
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@ -322,7 +329,7 @@ err:
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return ERR_PTR(ret);
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}
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static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
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static int mqueue_fill_super(struct super_block *sb, struct fs_context *fc)
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{
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struct inode *inode;
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struct ipc_namespace *ns = sb->s_fs_info;
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@ -343,18 +350,56 @@ static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
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return 0;
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}
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static struct dentry *mqueue_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name,
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void *data)
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static int mqueue_get_tree(struct fs_context *fc)
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{
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struct ipc_namespace *ns;
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if (flags & SB_KERNMOUNT) {
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ns = data;
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data = NULL;
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} else {
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ns = current->nsproxy->ipc_ns;
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struct mqueue_fs_context *ctx = fc->fs_private;
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put_user_ns(fc->user_ns);
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fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
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fc->s_fs_info = ctx->ipc_ns;
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return vfs_get_super(fc, vfs_get_keyed_super, mqueue_fill_super);
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}
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return mount_ns(fs_type, flags, data, ns, ns->user_ns, mqueue_fill_super);
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static void mqueue_fs_context_free(struct fs_context *fc)
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{
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struct mqueue_fs_context *ctx = fc->fs_private;
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if (ctx->ipc_ns)
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put_ipc_ns(ctx->ipc_ns);
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kfree(ctx);
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}
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static int mqueue_init_fs_context(struct fs_context *fc)
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{
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struct mqueue_fs_context *ctx;
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ctx = kzalloc(sizeof(struct mqueue_fs_context), GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
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ctx->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
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fc->fs_private = ctx;
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fc->ops = &mqueue_fs_context_ops;
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return 0;
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}
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static struct vfsmount *mq_create_mount(struct ipc_namespace *ns)
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{
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struct mqueue_fs_context *ctx;
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struct fs_context *fc;
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struct vfsmount *mnt;
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fc = fs_context_for_mount(&mqueue_fs_type, SB_KERNMOUNT);
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if (IS_ERR(fc))
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return ERR_CAST(fc);
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ctx = fc->fs_private;
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put_ipc_ns(ctx->ipc_ns);
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ctx->ipc_ns = get_ipc_ns(ns);
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mnt = fc_mount(fc);
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put_fs_context(fc);
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return mnt;
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}
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static void init_once(void *foo)
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@ -1522,15 +1567,22 @@ static const struct super_operations mqueue_super_ops = {
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.statfs = simple_statfs,
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};
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static const struct fs_context_operations mqueue_fs_context_ops = {
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.free = mqueue_fs_context_free,
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.get_tree = mqueue_get_tree,
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};
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static struct file_system_type mqueue_fs_type = {
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.name = "mqueue",
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.mount = mqueue_mount,
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.init_fs_context = mqueue_init_fs_context,
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.kill_sb = kill_litter_super,
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.fs_flags = FS_USERNS_MOUNT,
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};
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int mq_init_ns(struct ipc_namespace *ns)
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{
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struct vfsmount *m;
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ns->mq_queues_count = 0;
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ns->mq_queues_max = DFLT_QUEUESMAX;
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ns->mq_msg_max = DFLT_MSGMAX;
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@ -1538,12 +1590,10 @@ int mq_init_ns(struct ipc_namespace *ns)
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ns->mq_msg_default = DFLT_MSG;
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ns->mq_msgsize_default = DFLT_MSGSIZE;
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ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
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if (IS_ERR(ns->mq_mnt)) {
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int err = PTR_ERR(ns->mq_mnt);
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ns->mq_mnt = NULL;
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return err;
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}
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m = mq_create_mount(ns);
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if (IS_ERR(m))
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return PTR_ERR(m);
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ns->mq_mnt = m;
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return 0;
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}
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@ -42,7 +42,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
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goto fail;
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err = -ENOMEM;
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ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
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ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
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if (ns == NULL)
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goto fail_dec;
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