From 94628ad9440800ca0bd2436203a27c7576f769b7 Mon Sep 17 00:00:00 2001
From: Lee Trager <lee@trager.us>
Date: Thu, 10 Aug 2023 18:44:35 -0700
Subject: [PATCH] btrfs: copy dir permission and time when creating a stub
subvolume
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btrfs supports creating nested subvolumes however snapshots are not
recursive. When a snapshot is taken of a volume which contains a
subvolume the subvolume is replaced with a stub subvolume which has the
same name and uses inode number 2[1]. The stub subvolume kept the
directory name but did not set the time or permissions of the stub
subvolume. This resulted in all time information being the current time
and ownership defaulting to root. When subvolumes and snapshots are
created using unshare this results in a snapshot directory the user
created but has no permissions for.
Test case:
[vmuser@archvm ~]# sudo -i
[root@archvm ~]# mkdir -p /mnt/btrfs/test
[root@archvm ~]# chown vmuser:users /mnt/btrfs/test/
[root@archvm ~]# exit
logout
[vmuser@archvm ~]$ cd /mnt/btrfs/test
[vmuser@archvm test]$ unshare --user --keep-caps --map-auto --map-root-user
[root@archvm test]# btrfs subvolume create subvolume
Create subvolume './subvolume'
[root@archvm test]# btrfs subvolume create subvolume/subsubvolume
Create subvolume 'subvolume/subsubvolume'
[root@archvm test]# btrfs subvolume snapshot subvolume snapshot
Create a snapshot of 'subvolume' in './snapshot'
[root@archvm test]# exit
logout
[vmuser@archvm test]$ tree -ug
[vmuser users ] .
├── [vmuser users ] snapshot
│  └── [vmuser users ] subsubvolume <-- Without patch perm is root:root
└── [vmuser users ] subvolume
└── [vmuser users ] subsubvolume
5 directories, 0 files
[1] https://btrfs.readthedocs.io/en/latest/btrfs-subvolume.html#nested-subvolumes
Signed-off-by: Lee Trager <lee@trager.us>
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/inode.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ca0f4781b0e53..e211e88c6545f 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5585,11 +5585,11 @@ struct inode *btrfs_iget(struct super_block *s, u64 ino, struct btrfs_root *root
return btrfs_iget_path(s, ino, root, NULL);
}
-static struct inode *new_simple_dir(struct super_block *s,
+static struct inode *new_simple_dir(struct inode *dir,
struct btrfs_key *key,
struct btrfs_root *root)
{
- struct inode *inode = new_inode(s);
+ struct inode *inode = new_inode(dir->i_sb);
if (!inode)
return ERR_PTR(-ENOMEM);
@@ -5608,9 +5608,11 @@ static struct inode *new_simple_dir(struct super_block *s,
inode->i_fop = &simple_dir_operations;
inode->i_mode = S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO;
inode->i_mtime = current_time(inode);
- inode->i_atime = inode->i_mtime;
- inode->i_ctime = inode->i_mtime;
+ inode->i_atime = dir->i_atime;
+ inode->i_ctime = dir->i_ctime;
BTRFS_I(inode)->i_otime = inode->i_mtime;
+ inode->i_uid = dir->i_uid;
+ inode->i_gid = dir->i_gid;
return inode;
}
@@ -5669,7 +5671,7 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
if (ret != -ENOENT)
inode = ERR_PTR(ret);
else
- inode = new_simple_dir(dir->i_sb, &location, root);
+ inode = new_simple_dir(dir, &location, root);
} else {
inode = btrfs_iget(dir->i_sb, location.objectid, sub_root);
btrfs_put_root(sub_root);
--
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