diff mbox series

[v2] kernfs: attach uuid for every kernfs and report it in fsid

Message ID 20230731184731.64568-1-ivan@cloudflare.com
State New
Headers
Series [v2] kernfs: attach uuid for every kernfs and report it in fsid |

Commit Message

Ivan Babrou July 31, 2023, 6:47 p.m. UTC 
  The following two commits added the same thing for tmpfs:

* commit 2b4db79618ad ("tmpfs: generate random sb->s_uuid")
* commit 59cda49ecf6c ("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>

---
v2: Added a missing static and an ack from Jan Kara
---
 fs/kernfs/mount.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index d49606accb07..930026842359 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -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;
 }
 
+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);