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Subject[PATCH bpf-next 1/2] libfs: support RENAME_EXCHANGE in simple_rename()
Date
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@cloudflare.com>
---
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);

--
2.30.2
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