[PATCH 18/25] fsinfo: proc - add sb operation fsinfo() [ver #14]
From: David Howells <dhowells@redhat.com>
Date: 2019-06-24 14:11:39
Also in:
linux-fsdevel, lkml
Subsystem:
filesystems (vfs and infrastructure), proc filesystem, the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
From: Ian Kent <raven@themaw.net> The new fsinfo() system call adds a new super block operation ->fsinfo() which is used by file systems to provide file system specific information for fsinfo() requests. The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same function as sb operation ->show_options() so it needs to be implemented by any file system that provides ->show_options() as a minimum. Also add a simple FSINFO_ATTR_CAPABILITIES implementation. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: David Howells <dhowells@redhat.com> --- fs/proc/inode.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+)
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 5f8d215b3fd0..28c287aff6aa 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c@@ -24,6 +24,7 @@ #include <linux/seq_file.h> #include <linux/slab.h> #include <linux/mount.h> +#include <linux/fsinfo.h> #include <linux/uaccess.h>
@@ -115,6 +116,39 @@ static int proc_show_options(struct seq_file *seq, struct dentry *root) return 0; } +#ifdef CONFIG_FSINFO +/* + * Get filesystem information. + */ +static int proc_fsinfo(struct path *path, struct fsinfo_kparams *params) +{ + struct super_block *sb = path->dentry->d_sb; + struct pid_namespace *pid = sb->s_fs_info; + struct fsinfo_capabilities *caps; + + switch (params->request) { + case FSINFO_ATTR_CAPABILITIES: + caps = params->buffer; + fsinfo_set_cap(caps, FSINFO_CAP_IS_KERNEL_FS); + fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT); + return sizeof(*caps); + + case FSINFO_ATTR_PARAMETERS: + fsinfo_note_sb_params(params, sb->s_flags); + if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID)) + fsinfo_note_paramf(params, "gid", "%u", + from_kgid_munged(&init_user_ns, pid->pid_gid)); + if (pid->hide_pid != HIDEPID_OFF) + fsinfo_note_paramf(params, "hidepid", + "%u", pid->hide_pid); + return params->usage; + + default: + return generic_fsinfo(path, params); + } +} +#endif /* CONFIG_FSINFO */ + const struct super_operations proc_sops = { .alloc_inode = proc_alloc_inode, .free_inode = proc_free_inode,
@@ -122,6 +156,9 @@ const struct super_operations proc_sops = { .evict_inode = proc_evict_inode, .statfs = simple_statfs, .show_options = proc_show_options, +#ifdef CONFIG_FSINFO + .fsinfo = proc_fsinfo, +#endif }; enum {BIAS = -1U<<31};