kernfs: attach uuid for every kernfs and report it in fsid

The following two commits added the same thing for tmpfs:

* commit 2b4db79618 ("tmpfs: generate random sb->s_uuid")
* commit 59cda49ecf ("shmem: allow reporting fanotify events with file handles on tmpfs")

Having fsid allows using fanotify, which is especially handy for cgroups,
where one might be interested in knowing when they are created or removed.

Signed-off-by: Ivan Babrou <ivan@cloudflare.com>
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230731184731.64568-1-ivan@cloudflare.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ivan Babrou 2023-07-31 11:47:31 -07:00 committed by Greg Kroah-Hartman
parent 79038a9944
commit 0ce7c12e88

View File

@ -16,6 +16,8 @@
#include <linux/namei.h>
#include <linux/seq_file.h>
#include <linux/exportfs.h>
#include <linux/uuid.h>
#include <linux/statfs.h>
#include "kernfs-internal.h"
@ -45,8 +47,15 @@ static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
return 0;
}
static int kernfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
simple_statfs(dentry, buf);
buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
return 0;
}
const struct super_operations kernfs_sops = {
.statfs = simple_statfs,
.statfs = kernfs_statfs,
.drop_inode = generic_delete_inode,
.evict_inode = kernfs_evict_inode,
@ -351,6 +360,8 @@ int kernfs_get_tree(struct fs_context *fc)
}
sb->s_flags |= SB_ACTIVE;
uuid_gen(&sb->s_uuid);
down_write(&root->kernfs_supers_rwsem);
list_add(&info->node, &info->root->supers);
up_write(&root->kernfs_supers_rwsem);