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nsfs: add open_namespace()

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and call it from open_related_ns().

Link: https://lore.kernel.org/r/20240627-work-pidfs-v1-3-7e9ab6cc3bb1@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2024-06-27 16:11:41 +02:00
parent 85e4daaeb7
commit 460695a294
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
2 changed files with 34 additions and 25 deletions
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2
fs/internal.h
View File

@ -17,6 +17,7 @@ struct fs_context;
struct pipe_inode_info;
struct iov_iter;
struct mnt_idmap;
struct ns_common;
/*
* block/bdev.c
@ -321,3 +322,4 @@ struct stashed_operations {
int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data,
struct path *path);
void stashed_dentry_prune(struct dentry *dentry);
int open_namespace(struct ns_common *ns);

57
fs/nsfs.c
View File

@ -82,40 +82,47 @@ int ns_get_path(struct path *path, struct task_struct *task,
return ns_get_path_cb(path, ns_get_path_task, &args);
}
int open_related_ns(struct ns_common *ns,
struct ns_common *(*get_ns)(struct ns_common *ns))
/**
* open_namespace - open a namespace
* @ns: the namespace to open
*
* This will consume a reference to @ns indendent of success or failure.
*
* Return: A file descriptor on success or a negative error code on failure.
*/
int open_namespace(struct ns_common *ns)
{
struct path path = {};
struct ns_common *relative;
struct path path __free(path_put) = {};
struct file *f;
int err;
int fd;
fd = get_unused_fd_flags(O_CLOEXEC);
/* call first to consume reference */
err = path_from_stashed(&ns->stashed, nsfs_mnt, ns, &path);
if (err < 0)
return err;
CLASS(get_unused_fd, fd)(O_CLOEXEC);
if (fd < 0)
return fd;
relative = get_ns(ns);
if (IS_ERR(relative)) {
put_unused_fd(fd);
return PTR_ERR(relative);
}
err = path_from_stashed(&relative->stashed, nsfs_mnt, relative, &path);
if (err < 0) {
put_unused_fd(fd);
return err;
}
f = dentry_open(&path, O_RDONLY, current_cred());
path_put(&path);
if (IS_ERR(f)) {
put_unused_fd(fd);
fd = PTR_ERR(f);
} else
fd_install(fd, f);
if (IS_ERR(f))
return PTR_ERR(f);
return fd;
fd_install(fd, f);
return take_fd(fd);
}
int open_related_ns(struct ns_common *ns,
struct ns_common *(*get_ns)(struct ns_common *ns))
{
struct ns_common *relative;
relative = get_ns(ns);
if (IS_ERR(relative))
return PTR_ERR(relative);
return open_namespace(relative);
}
EXPORT_SYMBOL_GPL(open_related_ns);