// SPDX-License-Identifier: GPL-2.0-only
/*
*
* Copyright (C) 2011 Novell Inc.
*/
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/xattr.h>
#include <linux/posix_acl.h>
#include <linux/ratelimit.h>
#include <linux/fiemap.h>
#include "overlayfs.h"
int ovl_setattr(struct dentry *dentry, struct iattr *attr)
{
int err;
bool full_copy_up = false;
struct dentry *upperdentry;
const struct cred *old_cred;
err = setattr_prepare(dentry, attr);
if (err)
return err;
err = ovl_want_write(dentry);
if (err)
goto out;
if (attr->ia_valid & ATTR_SIZE) {
struct inode *realinode = d_inode(ovl_dentry_real(dentry));
err = -ETXTBSY;
if (atomic_read(&realinode->i_writecount) < 0)
goto out_drop_write;
/* Truncate should trigger data copy up as well */
full_copy_up = true;
}
if (!full_copy_up)
err = ovl_copy_up(dentry);
else
err = ovl_copy_up_with_data(dentry);
if (!err) {
struct inode *winode = NULL;
upperdentry = ovl_dentry_upper(dentry);
if (attr->ia_valid & ATTR_SIZE) {
winode = d_inode(upperdentry);
err = get_write_access(winode);
if (err)
goto out_drop_write;
}
if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
attr->ia_valid &= ~ATTR_MODE;
/*
* We might have to translate ovl file into real file object
* once use cases emerge. For now, simply don't let underlying
* filesystem rely on attr->ia_file
*/
attr->ia_valid &= ~ATTR_FILE;
/*
* If open(O_TRUNC) is done, VFS calls ->setattr with ATTR_OPEN
* set. Overlayfs does not pass O_TRUNC flag to underlying
* filesystem during open -> do not pass ATTR_OPEN. This
* disables optimization in fuse which assumes open(O_TRUNC)
* already set file size to 0. But we never passed O_TRUNC to
* fuse. So by clearing ATTR_OPEN, fuse will be forced to send
* setattr request to server.
*/
attr->ia_valid &= ~ATTR_OPEN;
inode_lock(upperdentry->d_inode);
old_cred = ovl_override_creds(dentry->d_sb);
err = notify_change(upperdentry, attr, NULL);
revert_creds(old_cred);
if (!err)
ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
inode_unlock(upperdentry->d_inode);
if (winode)
put_write_access(winode);
}
out_drop_write:
ovl_drop_write(dentry);
out:
return err;
}
static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
{
bool samefs = ovl_same_fs(dentry->d_sb);
unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
unsigned int xinoshift = 64 - xinobits;
if (samefs) {
/*
* When all layers are on the same fs, all real inode
* number are unique, so we use the overlay st_dev,
* which is friendly to du -x.
*/
stat->dev = dentry->d_sb->s_dev;
return 0;
} else if (xinobits) {
/*
* All inode numbers of underlying fs should not be using the
* high xinobits, so we use high xinobits to partition the
* overlay st_ino address space. The high bits holds the fsid
* (upper fsid is 0). The lowest xinobit is reserved for mapping
* the non-peresistent inode numbers range in case of overflow.
* This way all overlay inode numbers are unique and use the
* overlay st_dev.
*/
if (likely(!(stat->ino >> xinoshift))) {
stat->ino |= ((u64)fsid) << (xinoshift + 1);
stat->dev = dentry->d_sb->s_dev;
return 0;
} else if (ovl_xino_warn(dentry->d_sb)) {
pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
dentry, stat->ino, xinobits);
}
}
/* The inode could not be mapped to a unified st_ino address space */
if (S_ISDIR(dentry->d_inode->i_mode)) {
/*
* Always use the overlay st_dev for directories, so 'find
* -xdev' will scan the entire overlay mount and won't cross the
* overlay mount boundaries.
*
* If not all layers are on the same fs the pair {real st_ino;
* overlay st_dev} is not unique, so use the non persistent
* overlay st_ino for directories.
*/
stat->dev = dentry->d_sb->s_dev;
stat->ino = dentry->d_inode->i_ino;
}