From: Ian Kent <ra...@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 <ra...@themaw.net>
Signed-off-by: David Howells <dhowe...@redhat.com>
---

 fs/autofs/inode.c |   63 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/fs/autofs/inode.c b/fs/autofs/inode.c
index 58457ec0ab27..bd9126d8c541 100644
--- a/fs/autofs/inode.c
+++ b/fs/autofs/inode.c
@@ -11,6 +11,7 @@
 #include <linux/pagemap.h>
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
+#include <linux/fsinfo.h>
 
 #include "autofs_i.h"
 
@@ -101,6 +102,65 @@ static int autofs_show_options(struct seq_file *m, struct 
dentry *root)
        return 0;
 }
 
+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int autofs_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+       struct autofs_sb_info *sbi = autofs_sbi(path->dentry->d_sb);
+       struct inode *inode = d_inode(path->dentry->d_sb->s_root);
+       struct fsinfo_capabilities *caps;
+
+       switch (params->request) {
+       case FSINFO_ATTR_CAPABILITIES:
+               caps = params->buffer;
+               fsinfo_set_cap(caps, FSINFO_CAP_IS_AUTOMOUNTER_FS);
+               fsinfo_set_cap(caps, FSINFO_CAP_AUTOMOUNTS);
+               fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT);
+               return sizeof(*caps);
+
+       case FSINFO_ATTR_PARAMETERS:
+               fsinfo_note_paramf(params, "fd", "%d", sbi->pipefd);
+               if (!uid_eq(inode->i_uid, GLOBAL_ROOT_UID))
+                       fsinfo_note_paramf(params, "uid", "%u",
+                               from_kuid_munged(&init_user_ns, inode->i_uid));
+               if (!gid_eq(inode->i_gid, GLOBAL_ROOT_GID))
+                       fsinfo_note_paramf(params, "gid", "%u",
+                               from_kgid_munged(&init_user_ns, inode->i_gid));
+               fsinfo_note_paramf(params, "pgrp", "%d",
+                                  pid_vnr(sbi->oz_pgrp));
+               fsinfo_note_paramf(params, "timeout", "%lu",
+                                  sbi->exp_timeout/HZ);
+               fsinfo_note_paramf(params, "minproto", "%d",
+                                  sbi->min_proto);
+               fsinfo_note_paramf(params, "maxproto", "%d",
+                                  sbi->max_proto);
+               if (autofs_type_offset(sbi->type))
+                       fsinfo_note_param(params, "offset", NULL);
+               else if (autofs_type_direct(sbi->type))
+                       fsinfo_note_param(params, "direct", NULL);
+               else
+                       fsinfo_note_param(params, "indirect", NULL);
+               if (sbi->flags & AUTOFS_SBI_STRICTEXPIRE)
+                       fsinfo_note_param(params, "strictexpire", NULL);
+               if (sbi->flags & AUTOFS_SBI_IGNORE)
+                       fsinfo_note_param(params, "ignore", NULL);
+#ifdef CONFIG_CHECKPOINT_RESTORE
+               if (sbi->pipe)
+                       fsinfo_note_paramf(params, "pipe_ino",
+                                         "%ld", file_inode(sbi->pipe)->i_ino);
+               else
+                       fsinfo_note_param(params, "pipe_ino", "-1");
+#endif
+               return params->usage;
+
+       default:
+               return generic_fsinfo(path, params);
+       }
+}
+#endif /* CONFIG_FSINFO */
+
 static void autofs_evict_inode(struct inode *inode)
 {
        clear_inode(inode);
@@ -111,6 +171,9 @@ static const struct super_operations autofs_sops = {
        .statfs         = simple_statfs,
        .show_options   = autofs_show_options,
        .evict_inode    = autofs_evict_inode,
+#ifdef CONFIG_FSINFO
+       .fsinfo         = autofs_fsinfo,
+#endif
 };
 
 struct autofs_fs_context {

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