On Tue, Feb 27, 2024 at 03:28:18PM +0200, Amir Goldstein wrote: > > +int ovl_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, > > + const struct vfs_caps *caps, int setxattr_flags) > > +{ > > + int err; > > + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); > > + struct dentry *upperdentry = ovl_dentry_upper(dentry); > > + struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry); > > + const struct cred *old_cred; > > + > > + /* > > + * If the fscaps are to be remove from a lower file, check that they > > + * exist before copying up. > > + */ > > Don't you need to convert -ENODATA to 0 return value in this case? Do you mean that trying to remove an xattr that does not exist should return 0? Standard behavior is to return -ENODATA in this situation. > > > + if (!caps && !upperdentry) { > > + struct path realpath; > > + struct vfs_caps lower_caps; > > + > > + ovl_path_lower(dentry, &realpath); > > + old_cred = ovl_override_creds(dentry->d_sb); > > + err = vfs_get_fscaps(mnt_idmap(realpath.mnt), realdentry, > > + &lower_caps); > > + revert_creds(old_cred); > > + if (err) > > + goto out; > > + } > > + > > + err = ovl_want_write(dentry); > > + if (err) > > + goto out; > > + > > ovl_want_write() should after ovl_copy_up(), see: > 162d06444070 ("ovl: reorder ovl_want_write() after ovl_inode_lock()") Fixed. > > @@ -758,6 +826,8 @@ static const struct inode_operations ovl_symlink_inode_operations = { > > .get_link = ovl_get_link, > > .getattr = ovl_getattr, > > .listxattr = ovl_listxattr, > > + .get_fscaps = ovl_get_fscaps, > > + .set_fscaps = ovl_set_fscaps, > > .update_time = ovl_update_time, > > }; > > > > @@ -769,6 +839,8 @@ static const struct inode_operations ovl_special_inode_operations = { > > .get_inode_acl = ovl_get_inode_acl, > > .get_acl = ovl_get_acl, > > .set_acl = ovl_set_acl, > > + .get_fscaps = ovl_get_fscaps, > > + .set_fscaps = ovl_set_fscaps, > > .update_time = ovl_update_time, > > }; > > > > > Sorry, I did not understand the explanation why fscaps ops are needed > for non regular files. It does not look right to me. The kernel does not forbid XATTR_NAME_CAPS for non-regular files and will internally even try to read them from non-regular files during killpriv checks. If we do not add handlers then we will end up using the normal ovl xattr handlers, which call vfs_*xattr(). These will return an error for fscaps xattrs after this series, which would be a change in behavior for overlayfs and make it behave differently from other filesystems.