From 935c6912b198f60a812b7dada21027b5aac7c461 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 1 Nov 2018 23:07:25 +0000 Subject: 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 Signed-off-by: Al Viro --- ipc/mqueue.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 72 insertions(+), 22 deletions(-) (limited to 'ipc/mqueue.c') 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 #include #include +#include #include #include #include @@ -42,6 +43,10 @@ #include #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; } -- cgit v1.2.3-70-g09d2