Re: [PATCH bpf-next v2 1/3] libfs: support RENAME_EXCHANGE in simple_rename()
From: Daniel Borkmann
Date: Wed Oct 27 2021 - 19:21:22 EST
[ Adding Miklos & Greg to Cc for review given e0e0be8a8355 ("libfs: support RENAME_NOREPLACE in
simple_rename()"). If you have a chance, would be great if you could take a look, thanks! ]
On 10/21/21 5:15 PM, Lorenz Bauer wrote:
Allow atomic exchange via RENAME_EXCHANGE when using simple_rename.
This affects binderfs, ramfs, hubetlbfs and bpffs. There isn't much
to do except update the various *time fields.
Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
---
fs/libfs.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/libfs.c b/fs/libfs.c
index 51b4de3b3447..93c03d593749 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -455,9 +455,12 @@ int simple_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
struct inode *inode = d_inode(old_dentry);
int they_are_dirs = d_is_dir(old_dentry);
- if (flags & ~RENAME_NOREPLACE)
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
return -EINVAL;
+ if (flags & RENAME_EXCHANGE)
+ goto done;
+
if (!simple_empty(new_dentry))
return -ENOTEMPTY;
@@ -472,6 +475,7 @@ int simple_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
inc_nlink(new_dir);
}
+done:
old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
new_dir->i_mtime = inode->i_ctime = current_time(old_dir);