text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   * All Rights Reserved.
   */
  #include "xfs.h"
  #include "xfs_fs.h"
  #include "xfs_shared.h"
  #include "xfs_format.h"
  #include "xfs_log_format.h"
  #include "xfs_trans_resv.h"
  #include "xfs_mount.h"
  #include "xfs_inode.h"
  #include "xfs_acl.h"
  #include "xfs_quota.h"
  #include "xfs_attr.h"
  #include "xfs_trans.h"
  #include "xfs_trace.h"
  #include "xfs_icache.h"
  #include "xfs_symlink.h"
  #include "xfs_dir2.h"
  #include "xfs_iomap.h"
  #include "xfs_error.h"
  #include "xfs_ioctl.h"
  
  #include <linux/posix_acl.h>
  #include <linux/security.h>
  #include <linux/iversion.h>
  #include <linux/fiemap.h>
  
  /*
   * Directories have different lock order w.r.t. mmap_lock compared to regular
   * files. This is due to readdir potentially triggering page faults on a user
   * buffer inside filldir(), and this happens with the ilock on the directory
   * held. For regular files, the lock order is the other way around - the
   * mmap_lock is taken during the page fault, and then we lock the ilock to do
   * block mapping. Hence we need a different class for the directory ilock so
   * that lockdep can tell them apart.
   */
  static struct lock_class_key xfs_nondir_ilock_class;
  static struct lock_class_key xfs_dir_ilock_class;
  
  static int
  xfs_initxattrs(
  	struct inode		*inode,
  	const struct xattr	*xattr_array,
  	void			*fs_info)
  {
  	const struct xattr	*xattr;
  	struct xfs_inode	*ip = XFS_I(inode);
  	int			error = 0;
  
  	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
  		struct xfs_da_args	args = {
  			.dp		= ip,
  			.attr_filter	= XFS_ATTR_SECURE,
  			.name		= xattr->name,
  			.namelen	= strlen(xattr->name),
  			.value		= xattr->value,
  			.valuelen	= xattr->value_len,
  		};
  		error = xfs_attr_set(&args);
  		if (error < 0)
  			break;
  	}
  	return error;
  }
  
  /*
   * Hook in SELinux.  This is not quite correct yet, what we really need
   * here (as we do for default ACLs) is a mechanism by which creation of
   * these attrs can be journalled at inode creation time (along with the
   * inode, of course, such that log replay can't cause these to be lost).
   */
  
  STATIC int
  xfs_init_security(
  	struct inode	*inode,
  	struct inode	*dir,
  	const struct qstr *qstr)
  {
  	return security_inode_init_security(inode, dir, qstr,
  					     &xfs_initxattrs, NULL);
  }
  
  static void
  xfs_dentry_to_name(
  	struct xfs_name	*namep,
  	struct dentry	*dentry)
  {
  	namep->name = dentry->d_name.name;
  	namep->len = dentry->d_name.len;
  	namep->type = XFS_DIR3_FT_UNKNOWN;
  }
  
  static int
  xfs_dentry_mode_to_name(
  	struct xfs_name	*namep,
  	struct dentry	*dentry,
  	int		mode)
  {
  	namep->name = dentry->d_name.name;
  	namep->len = dentry->d_name.len;
  	namep->type = xfs_mode_to_ftype(mode);
  
  	if (unlikely(namep->type == XFS_DIR3_FT_UNKNOWN))
  		return -EFSCORRUPTED;
  
  	return 0;
  }
  
  STATIC void
  xfs_cleanup_inode(
  	struct inode	*dir,
  	struct inode	*inode,
  	struct dentry	*dentry)
  {
  	struct xfs_name	teardown;
  
  	/* Oh, the horror.
  	 * If we can't add the ACL or we fail in
  	 * xfs_init_security we must back out.
  	 * ENOSPC can hit here, among other things.
  	 */
  	xfs_dentry_to_name(&teardown, dentry);
  
  	xfs_remove(XFS_I(dir), &teardown, XFS_I(inode));
  }
  
  /*
   * Check to see if we are likely to need an extended attribute to be added to
   * the inode we are about to allocate. This allows the attribute fork to be
   * created during the inode allocation, reducing the number of transactions we
   * need to do in this fast path.
   *
   * The security checks are optimistic, but not guaranteed. The two LSMs that
   * require xattrs to be added here (selinux and smack) are also the only two
   * LSMs that add a sb->s_security structure to the superblock. Hence if security
   * is enabled and sb->s_security is set, we have a pretty good idea that we are
   * going to be asked to add a security xattr immediately after allocating the
   * xfs inode and instantiating the VFS inode.
   */
  static inline bool
  xfs_create_need_xattr(
  	struct inode	*dir,
  	struct posix_acl *default_acl,
  	struct posix_acl *acl)
  {
  	if (acl)
  		return true;
  	if (default_acl)
  		return true;
  #if IS_ENABLED(CONFIG_SECURITY)
  	if (dir->i_sb->s_security)
  		return true;
  #endif
  	return false;
  }
  
  
  STATIC int
  xfs_generic_create(
  	struct user_namespace	*mnt_userns,
  	struct inode	*dir,
  	struct dentry	*dentry,
  	umode_t		mode,
  	dev_t		rdev,
  	bool		tmpfile)	/* unnamed file */
  {
  	struct inode	*inode;
  	struct xfs_inode *ip = NULL;
  	struct posix_acl *default_acl, *acl;
  	struct xfs_name	name;
  	int		error;
  
  	/*
  	 * Irix uses Missed'em'V split, but doesn't want to see
  	 * the upper 5 bits of (14bit) major.
  	 */
  	if (S_ISCHR(mode) || S_ISBLK(mode)) {
  		if (unlikely(!sysv_valid_dev(rdev) || MAJOR(rdev) & ~0x1ff))
  			return -EINVAL;
  	} else {
  		rdev = 0;
  	}
  
  	error = posix_acl_create(dir, &mode, &default_acl, &acl);
  	if (error)
  		return error;
  
  	/* Verify mode is valid also for tmpfile case */
  	error = xfs_dentry_mode_to_name(&name, dentry, mode);
  	if (unlikely(error))
  		goto out_free_acl;
  
  	if (!tmpfile) {
  		error = xfs_create(mnt_userns, XFS_I(dir), &name, mode, rdev,
  				xfs_create_need_xattr(dir, default_acl, acl),
  				&ip);
  	} else {
  		error = xfs_create_tmpfile(mnt_userns, XFS_I(dir), mode, &ip);
  	}
  	if (unlikely(error))
  		goto out_free_acl;
  
  	inode = VFS_I(ip);
  
  	error = xfs_init_security(inode, dir, &dentry->d_name);
  	if (unlikely(error))
  		goto out_cleanup_inode;
  
  #ifdef CONFIG_XFS_POSIX_ACL
  	if (default_acl) {
  		error = __xfs_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
  		if (error)
  			goto out_cleanup_inode;
  	}
  	if (acl) {
  		error = __xfs_set_acl(inode, acl, ACL_TYPE_ACCESS);
  		if (error)
  			goto out_cleanup_inode;
  	}
  #endif
  
  	xfs_setup_iops(ip);
  
  	if (tmpfile) {
  		/*
  		 * The VFS requires that any inode fed to d_tmpfile must have
  		 * nlink == 1 so that it can decrement the nlink in d_tmpfile.
  		 * However, we created the temp file with nlink == 0 because
  		 * we're not allowed to put an inode with nlink > 0 on the
  		 * unlinked list.  Therefore we have to set nlink to 1 so that
  		 * d_tmpfile can immediately set it back to zero.
  		 */
  		set_nlink(inode, 1);
  		d_tmpfile(dentry, inode);
  	} else
  		d_instantiate(dentry, inode);
  
  	xfs_finish_inode_setup(ip);
  
   out_free_acl:
  	posix_acl_release(default_acl);
  	posix_acl_release(acl);
  	return error;
  
   out_cleanup_inode:
  	xfs_finish_inode_setup(ip);
  	if (!tmpfile)
  		xfs_cleanup_inode(dir, inode, dentry);
  	xfs_irele(ip);
  	goto out_free_acl;
  }
  
  STATIC int
  xfs_vn_mknod(
  	struct user_namespace	*mnt_userns,
  	struct inode		*dir,
  	struct dentry		*dentry,
  	umode_t			mode,
  	dev_t			rdev)
  {
  	return xfs_generic_create(mnt_userns, dir, dentry, mode, rdev, false);
  }
  
  STATIC int
  xfs_vn_create(
  	struct user_namespace	*mnt_userns,
  	struct inode		*dir,
  	struct dentry		*dentry,
  	umode_t			mode,
  	bool			flags)
  {
  	return xfs_generic_create(mnt_userns, dir, dentry, mode, 0, false);
  }
  
  STATIC int
  xfs_vn_mkdir(
  	struct user_namespace	*mnt_userns,
  	struct inode		*dir,
  	struct dentry		*dentry,
  	umode_t			mode)
  {
  	return xfs_generic_create(mnt_userns, dir, dentry, mode | S_IFDIR, 0,
  				  false);
  }
  
  STATIC struct dentry *
  xfs_vn_lookup(
  	struct inode	*dir,
  	struct dentry	*dentry,
  	unsigned int flags)
  {
  	struct inode *inode;
  	struct xfs_inode *cip;
  	struct xfs_name	name;
  	int		error;
  
  	if (dentry->d_name.len >= MAXNAMELEN)
  		return ERR_PTR(-ENAMETOOLONG);
  
  	xfs_dentry_to_name(&name, dentry);
  	error = xfs_lookup(XFS_I(dir), &name, &cip, NULL);
  	if (likely(!error))
  		inode = VFS_I(cip);
  	else if (likely(error == -ENOENT))
  		inode = NULL;
  	else
  		inode = ERR_PTR(error);
  	return d_splice_alias(inode, dentry);
  }
  
  STATIC struct dentry *
  xfs_vn_ci_lookup(
  	struct inode	*dir,
  	struct dentry	*dentry,
  	unsigned int flags)
  {
  	struct xfs_inode *ip;
  	struct xfs_name	xname;
  	struct xfs_name ci_name;
  	struct qstr	dname;
  	int		error;
  
  	if (dentry->d_name.len >= MAXNAMELEN)
  		return ERR_PTR(-ENAMETOOLONG);
  
  	xfs_dentry_to_name(&xname, dentry);
  	error = xfs_lookup(XFS_I(dir), &xname, &ip, &ci_name);
  	if (unlikely(error)) {
  		if (unlikely(error != -ENOENT))
  			return ERR_PTR(error);
  		/*
  		 * call d_add(dentry, NULL) here when d_drop_negative_children
  		 * is called in xfs_vn_mknod (ie. allow negative dentries
  		 * with CI filesystems).
  		 */
  		return NULL;
  	}
  
  	/* if exact match, just splice and exit */
  	if (!ci_name.name)
  		return d_splice_alias(VFS_I(ip), dentry);
  
  	/* else case-insensitive match... */
  	dname.name = ci_name.name;
  	dname.len = ci_name.len;
  	dentry = d_add_ci(dentry, VFS_I(ip), &dname);
  	kmem_free(ci_name.name);
  	return dentry;
  }
  
  STATIC int
  xfs_vn_link(
  	struct dentry	*old_dentry,
  	struct inode	*dir,
  	struct dentry	*dentry)
  {
  	struct inode	*inode = d_inode(old_dentry);
  	struct xfs_name	name;
  	int		error;
  
  	error = xfs_dentry_mode_to_name(&name, dentry, inode->i_mode);
  	if (unlikely(error))
  		return error;
  
  	error = xfs_link(XFS_I(dir), XFS_I(inode), &name);
  	if (unlikely(error))
  		return error;
  
  	ihold(inode);
  	d_instantiate(dentry, inode);
  	return 0;
  }
  
  STATIC int
  xfs_vn_unlink(
  	struct inode	*dir,
  	struct dentry	*dentry)
  {
  	struct xfs_name	name;
  	int		error;
  
  	xfs_dentry_to_name(&name, dentry);
  
  	error = xfs_remove(XFS_I(dir), &name, XFS_I(d_inode(dentry)));
  	if (error)
  		return error;
  
  	/*
  	 * With unlink, the VFS makes the dentry "negative": no inode,
  	 * but still hashed. This is incompatible with case-insensitive
  	 * mode, so invalidate (unhash) the dentry in CI-mode.
  	 */
  	if (xfs_has_asciici(XFS_M(dir->i_sb)))
  		d_invalidate(dentry);
  	return 0;
  }
  
  STATIC int
  xfs_vn_symlink(
  	struct user_namespace	*mnt_userns,
  	struct inode		*dir,
  	struct dentry		*dentry,
  	const char		*symname)
  {
  	struct inode	*inode;
  	struct xfs_inode *cip = NULL;
  	struct xfs_name	name;
  	int		error;
  	umode_t		mode;
  
  	mode = S_IFLNK |
  		(irix_symlink_mode ? 0777 & ~current_umask() : S_IRWXUGO);
  	error = xfs_dentry_mode_to_name(&name, dentry, mode);
  	if (unlikely(error))
  		goto out;
  
  	error = xfs_symlink(mnt_userns, XFS_I(dir), &name, symname, mode, &cip);
  	if (unlikely(error))
  		goto out;
  
  	inode = VFS_I(cip);
  
  	error = xfs_init_security(inode, dir, &dentry->d_name);
  	if (unlikely(error))
  		goto out_cleanup_inode;
  
  	xfs_setup_iops(cip);
  
  	d_instantiate(dentry, inode);
  	xfs_finish_inode_setup(cip);
  	return 0;
  
   out_cleanup_inode:
  	xfs_finish_inode_setup(cip);
  	xfs_cleanup_inode(dir, inode, dentry);
  	xfs_irele(cip);
   out:
  	return error;
  }
  
  STATIC int
  xfs_vn_rename(
  	struct user_namespace	*mnt_userns,
  	struct inode		*odir,
  	struct dentry		*odentry,
  	struct inode		*ndir,
  	struct dentry		*ndentry,
  	unsigned int		flags)
  {
  	struct inode	*new_inode = d_inode(ndentry);
  	int		omode = 0;
  	int		error;
  	struct xfs_name	oname;
  	struct xfs_name	nname;
  
  	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
  		return -EINVAL;
  
  	/* if we are exchanging files, we need to set i_mode of both files */
  	if (flags & RENAME_EXCHANGE)
  		omode = d_inode(ndentry)->i_mode;
  
  	error = xfs_dentry_mode_to_name(&oname, odentry, omode);
  	if (omode && unlikely(error))
  		return error;
  
  	error = xfs_dentry_mode_to_name(&nname, ndentry,
  					d_inode(odentry)->i_mode);
  	if (unlikely(error))
  		return error;
  
  	return xfs_rename(mnt_userns, XFS_I(odir), &oname,
  			  XFS_I(d_inode(odentry)), XFS_I(ndir), &nname,
  			  new_inode ? XFS_I(new_inode) : NULL, flags);
  }
  
  /*
   * careful here - this function can get called recursively, so
   * we need to be very careful about how much stack we use.
   * uio is kmalloced for this reason...
   */
  STATIC const char *
  xfs_vn_get_link(
  	struct dentry		*dentry,
  	struct inode		*inode,
  	struct delayed_call	*done)
  {
  	char			*link;
  	int			error = -ENOMEM;
  
  	if (!dentry)
  		return ERR_PTR(-ECHILD);
  
  	link = kmalloc(XFS_SYMLINK_MAXLEN+1, GFP_KERNEL);
  	if (!link)
  		goto out_err;
  
  	error = xfs_readlink(XFS_I(d_inode(dentry)), link);
  	if (unlikely(error))
  		goto out_kfree;
  
  	set_delayed_call(done, kfree_link, link);
  	return link;
  
   out_kfree:
  	kfree(link);
   out_err:
  	return ERR_PTR(error);
  }
  
  static uint32_t
  xfs_stat_blksize(
  	struct xfs_inode	*ip)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  
  	/*
  	 * If the file blocks are being allocated from a realtime volume, then
  	 * always return the realtime extent size.
  	 */
  	if (XFS_IS_REALTIME_INODE(ip))
  		return XFS_FSB_TO_B(mp, xfs_get_extsz_hint(ip));
  
  	/*
  	 * Allow large block sizes to be reported to userspace programs if the
  	 * "largeio" mount option is used.
  	 *
  	 * If compatibility mode is specified, simply return the basic unit of
  	 * caching so that we don't get inefficient read/modify/write I/O from
  	 * user apps. Otherwise....
  	 *
  	 * If the underlying volume is a stripe, then return the stripe width in
  	 * bytes as the recommended I/O size. It is not a stripe and we've set a
  	 * default buffered I/O size, return that, otherwise return the compat
  	 * default.
  	 */
  	if (xfs_has_large_iosize(mp)) {
  		if (mp->m_swidth)
  			return XFS_FSB_TO_B(mp, mp->m_swidth);
  		if (xfs_has_allocsize(mp))
  			return 1U << mp->m_allocsize_log;
  	}
  
  	return PAGE_SIZE;
  }
  
  STATIC int
  xfs_vn_getattr(
  	struct user_namespace	*mnt_userns,
  	const struct path	*path,
  	struct kstat		*stat,
  	u32			request_mask,
  	unsigned int		query_flags)
  {
  	struct inode		*inode = d_inode(path->dentry);
  	struct xfs_inode	*ip = XFS_I(inode);
  	struct xfs_mount	*mp = ip->i_mount;
  
  	trace_xfs_getattr(ip);
  
  	if (xfs_is_shutdown(mp))
  		return -EIO;
  
  	stat->size = XFS_ISIZE(ip);
  	stat->dev = inode->i_sb->s_dev;
  	stat->mode = inode->i_mode;
  	stat->nlink = inode->i_nlink;
  	stat->uid = i_uid_into_mnt(mnt_userns, inode);
  	stat->gid = i_gid_into_mnt(mnt_userns, inode);
  	stat->ino = ip->i_ino;
  	stat->atime = inode->i_atime;
  	stat->mtime = inode->i_mtime;
  	stat->ctime = inode->i_ctime;
  	stat->blocks = XFS_FSB_TO_BB(mp, ip->i_nblocks + ip->i_delayed_blks);
  
  	if (xfs_has_v3inodes(mp)) {
  		if (request_mask & STATX_BTIME) {
  			stat->result_mask |= STATX_BTIME;
  			stat->btime = ip->i_crtime;
  		}
  	}
  
  	/*
  	 * Note: If you add another clause to set an attribute flag, please
  	 * update attributes_mask below.
  	 */
  	if (ip->i_diflags & XFS_DIFLAG_IMMUTABLE)
  		stat->attributes |= STATX_ATTR_IMMUTABLE;
  	if (ip->i_diflags & XFS_DIFLAG_APPEND)
  		stat->attributes |= STATX_ATTR_APPEND;
  	if (ip->i_diflags & XFS_DIFLAG_NODUMP)
  		stat->attributes |= STATX_ATTR_NODUMP;
  
  	stat->attributes_mask |= (STATX_ATTR_IMMUTABLE |
  				  STATX_ATTR_APPEND |
  				  STATX_ATTR_NODUMP);
  
  	switch (inode->i_mode & S_IFMT) {
  	case S_IFBLK:
  	case S_IFCHR:
  		stat->blksize = BLKDEV_IOSIZE;
  		stat->rdev = inode->i_rdev;
  		break;
  	default:
  		stat->blksize = xfs_stat_blksize(ip);
  		stat->rdev = 0;
  		break;
  	}
  
  	return 0;
  }
  
  static void
  xfs_setattr_mode(
  	struct xfs_inode	*ip,
  	struct iattr		*iattr)
  {
  	struct inode		*inode = VFS_I(ip);
  	umode_t			mode = iattr->ia_mode;
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  
  	inode->i_mode &= S_IFMT;
  	inode->i_mode |= mode & ~S_IFMT;
  }
  
  void
  xfs_setattr_time(
  	struct xfs_inode	*ip,
  	struct iattr		*iattr)
  {
  	struct inode		*inode = VFS_I(ip);
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  
  	if (iattr->ia_valid & ATTR_ATIME)
  		inode->i_atime = iattr->ia_atime;
  	if (iattr->ia_valid & ATTR_CTIME)
  		inode->i_ctime = iattr->ia_ctime;
  	if (iattr->ia_valid & ATTR_MTIME)
  		inode->i_mtime = iattr->ia_mtime;
  }
  
  static int
  xfs_vn_change_ok(
  	struct user_namespace	*mnt_userns,
  	struct dentry		*dentry,
  	struct iattr		*iattr)
  {
  	struct xfs_mount	*mp = XFS_I(d_inode(dentry))->i_mount;
  
  	if (xfs_is_readonly(mp))
  		return -EROFS;
  
  	if (xfs_is_shutdown(mp))
  		return -EIO;
  
  	return setattr_prepare(mnt_userns, dentry, iattr);
  }
  
  /*
   * Set non-size attributes of an inode.
   *
   * Caution: The caller of this function is responsible for calling
   * setattr_prepare() or otherwise verifying the change is fine.
   */
  static int
  xfs_setattr_nonsize(
  	struct user_namespace	*mnt_userns,
  	struct xfs_inode	*ip,
  	struct iattr		*iattr)
  {
  	xfs_mount_t		*mp = ip->i_mount;
  	struct inode		*inode = VFS_I(ip);
  	int			mask = iattr->ia_valid;
  	xfs_trans_t		*tp;
  	int			error;
  	kuid_t			uid = GLOBAL_ROOT_UID, iuid = GLOBAL_ROOT_UID;
  	kgid_t			gid = GLOBAL_ROOT_GID, igid = GLOBAL_ROOT_GID;
  	struct xfs_dquot	*udqp = NULL, *gdqp = NULL;
  	struct xfs_dquot	*olddquot1 = NULL, *olddquot2 = NULL;
  
  	ASSERT((mask & ATTR_SIZE) == 0);
  
  	/*
  	 * If disk quotas is on, we make sure that the dquots do exist on disk,
  	 * before we start any other transactions. Trying to do this later
  	 * is messy. We don't care to take a readlock to look at the ids
  	 * in inode here, because we can't hold it across the trans_reserve.
  	 * If the IDs do change before we take the ilock, we're covered
  	 * because the i_*dquot fields will get updated anyway.
  	 */
  	if (XFS_IS_QUOTA_ON(mp) && (mask & (ATTR_UID|ATTR_GID))) {
  		uint	qflags = 0;
  
  		if ((mask & ATTR_UID) && XFS_IS_UQUOTA_ON(mp)) {
  			uid = iattr->ia_uid;
  			qflags |= XFS_QMOPT_UQUOTA;
  		} else {
  			uid = inode->i_uid;
  		}
  		if ((mask & ATTR_GID) && XFS_IS_GQUOTA_ON(mp)) {
  			gid = iattr->ia_gid;
  			qflags |= XFS_QMOPT_GQUOTA;
  		}  else {
  			gid = inode->i_gid;
  		}
  
  		/*
  		 * We take a reference when we initialize udqp and gdqp,
  		 * so it is important that we never blindly double trip on
  		 * the same variable. See xfs_create() for an example.
  		 */
  		ASSERT(udqp == NULL);
  		ASSERT(gdqp == NULL);
  		error = xfs_qm_vop_dqalloc(ip, uid, gid, ip->i_projid,
  					   qflags, &udqp, &gdqp, NULL);
  		if (error)
  			return error;
  	}
  
  	error = xfs_trans_alloc_ichange(ip, udqp, gdqp, NULL,
  			capable(CAP_FOWNER), &tp);
  	if (error)
  		goto out_dqrele;
  
  	/*
  	 * Change file ownership.  Must be the owner or privileged.
  	 */
  	if (mask & (ATTR_UID|ATTR_GID)) {
  		/*
  		 * These IDs could have changed since we last looked at them.
  		 * But, we're assured that if the ownership did change
  		 * while we didn't have the inode locked, inode's dquot(s)
  		 * would have changed also.
  		 */
  		iuid = inode->i_uid;
  		igid = inode->i_gid;
  		gid = (mask & ATTR_GID) ? iattr->ia_gid : igid;
  		uid = (mask & ATTR_UID) ? iattr->ia_uid : iuid;
  
  		/*
  		 * CAP_FSETID overrides the following restrictions:
  		 *
  		 * The set-user-ID and set-group-ID bits of a file will be
  		 * cleared upon successful return from chown()
  		 */
  		if ((inode->i_mode & (S_ISUID|S_ISGID)) &&
  		    !capable(CAP_FSETID))
  			inode->i_mode &= ~(S_ISUID|S_ISGID);
  
  		/*
  		 * Change the ownerships and register quota modifications
  		 * in the transaction.
  		 */
  		if (!uid_eq(iuid, uid)) {
  			if (XFS_IS_UQUOTA_ON(mp)) {
  				ASSERT(mask & ATTR_UID);
  				ASSERT(udqp);
  				olddquot1 = xfs_qm_vop_chown(tp, ip,
  							&ip->i_udquot, udqp);
  			}
  			inode->i_uid = uid;
  		}
  		if (!gid_eq(igid, gid)) {
  			if (XFS_IS_GQUOTA_ON(mp)) {
  				ASSERT(xfs_has_pquotino(mp) ||
  				       !XFS_IS_PQUOTA_ON(mp));
  				ASSERT(mask & ATTR_GID);
  				ASSERT(gdqp);
  				olddquot2 = xfs_qm_vop_chown(tp, ip,
  							&ip->i_gdquot, gdqp);
  			}
  			inode->i_gid = gid;
  		}
  	}
  
  	if (mask & ATTR_MODE)
  		xfs_setattr_mode(ip, iattr);
  	if (mask & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME))
  		xfs_setattr_time(ip, iattr);
  
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	XFS_STATS_INC(mp, xs_ig_attrchg);
  
  	if (xfs_has_wsync(mp))
  		xfs_trans_set_sync(tp);
  	error = xfs_trans_commit(tp);
  
  	/*
  	 * Release any dquot(s) the inode had kept before chown.
  	 */
  	xfs_qm_dqrele(olddquot1);
  	xfs_qm_dqrele(olddquot2);
  	xfs_qm_dqrele(udqp);
  	xfs_qm_dqrele(gdqp);
  
  	if (error)
  		return error;
  
  	/*
  	 * XXX(hch): Updating the ACL entries is not atomic vs the i_mode
  	 * 	     update.  We could avoid this with linked transactions
  	 * 	     and passing down the transaction pointer all the way
  	 *	     to attr_set.  No previous user of the generic
  	 * 	     Posix ACL code seems to care about this issue either.
  	 */
  	if (mask & ATTR_MODE) {
  		error = posix_acl_chmod(mnt_userns, inode, inode->i_mode);
  		if (error)
  			return error;
  	}
  
  	return 0;
  
  out_dqrele:
  	xfs_qm_dqrele(udqp);
  	xfs_qm_dqrele(gdqp);
  	return error;
  }
  
  /*
   * Truncate file.  Must have write permission and not be a directory.
   *
   * Caution: The caller of this function is responsible for calling
   * setattr_prepare() or otherwise verifying the change is fine.
   */
  STATIC int
  xfs_setattr_size(
  	struct user_namespace	*mnt_userns,
  	struct xfs_inode	*ip,
  	struct iattr		*iattr)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct inode		*inode = VFS_I(ip);
  	xfs_off_t		oldsize, newsize;
  	struct xfs_trans	*tp;
  	int			error;
  	uint			lock_flags = 0;
  	bool			did_zeroing = false;
  
  	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
  	ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));
  	ASSERT(S_ISREG(inode->i_mode));
  	ASSERT((iattr->ia_valid & (ATTR_UID|ATTR_GID|ATTR_ATIME|ATTR_ATIME_SET|
  		ATTR_MTIME_SET|ATTR_TIMES_SET)) == 0);
  
  	oldsize = inode->i_size;
  	newsize = iattr->ia_size;
  
  	/*
  	 * Short circuit the truncate case for zero length files.
  	 */
  	if (newsize == 0 && oldsize == 0 && ip->i_df.if_nextents == 0) {
  		if (!(iattr->ia_valid & (ATTR_CTIME|ATTR_MTIME)))
  			return 0;
  
  		/*
  		 * Use the regular setattr path to update the timestamps.
  		 */
  		iattr->ia_valid &= ~ATTR_SIZE;
  		return xfs_setattr_nonsize(mnt_userns, ip, iattr);
  	}
  
  	/*
  	 * Make sure that the dquots are attached to the inode.
  	 */
  	error = xfs_qm_dqattach(ip);
  	if (error)
  		return error;
  
  	/*
  	 * Wait for all direct I/O to complete.
  	 */
  	inode_dio_wait(inode);
  
  	/*
  	 * File data changes must be complete before we start the transaction to
  	 * modify the inode.  This needs to be done before joining the inode to
  	 * the transaction because the inode cannot be unlocked once it is a
  	 * part of the transaction.
  	 *
  	 * Start with zeroing any data beyond EOF that we may expose on file
  	 * extension, or zeroing out the rest of the block on a downward
  	 * truncate.
  	 */
  	if (newsize > oldsize) {
  		trace_xfs_zero_eof(ip, oldsize, newsize - oldsize);
  		error = xfs_zero_range(ip, oldsize, newsize - oldsize,
  				&did_zeroing);
  	} else {
  		/*
  		 * iomap won't detect a dirty page over an unwritten block (or a
  		 * cow block over a hole) and subsequently skips zeroing the
  		 * newly post-EOF portion of the page. Flush the new EOF to
  		 * convert the block before the pagecache truncate.
  		 */
  		error = filemap_write_and_wait_range(inode->i_mapping, newsize,
  						     newsize);
  		if (error)
  			return error;
  		error = xfs_truncate_page(ip, newsize, &did_zeroing);
  	}
  
  	if (error)
  		return error;
  
  	/*
  	 * We've already locked out new page faults, so now we can safely remove
  	 * pages from the page cache knowing they won't get refaulted until we
  	 * drop the XFS_MMAP_EXCL lock after the extent manipulations are
  	 * complete. The truncate_setsize() call also cleans partial EOF page
  	 * PTEs on extending truncates and hence ensures sub-page block size
  	 * filesystems are correctly handled, too.
  	 *
  	 * We have to do all the page cache truncate work outside the
  	 * transaction context as the "lock" order is page lock->log space
  	 * reservation as defined by extent allocation in the writeback path.
  	 * Hence a truncate can fail with ENOMEM from xfs_trans_alloc(), but
  	 * having already truncated the in-memory version of the file (i.e. made
  	 * user visible changes). There's not much we can do about this, except
  	 * to hope that the caller sees ENOMEM and retries the truncate
  	 * operation.
  	 *
  	 * And we update in-core i_size and truncate page cache beyond newsize
  	 * before writeback the [i_disk_size, newsize] range, so we're
  	 * guaranteed not to write stale data past the new EOF on truncate down.
  	 */
  	truncate_setsize(inode, newsize);
  
  	/*
  	 * We are going to log the inode size change in this transaction so
  	 * any previous writes that are beyond the on disk EOF and the new
  	 * EOF that have not been written out need to be written here.  If we
  	 * do not write the data out, we expose ourselves to the null files
  	 * problem. Note that this includes any block zeroing we did above;
  	 * otherwise those blocks may not be zeroed after a crash.
  	 */
  	if (did_zeroing ||
  	    (newsize > ip->i_disk_size && oldsize != ip->i_disk_size)) {
  		error = filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
  						ip->i_disk_size, newsize - 1);
  		if (error)
  			return error;
  	}
  
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
  	if (error)
  		return error;
  
  	lock_flags |= XFS_ILOCK_EXCL;
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, 0);
  
  	/*
  	 * Only change the c/mtime if we are changing the size or we are
  	 * explicitly asked to change it.  This handles the semantic difference
  	 * between truncate() and ftruncate() as implemented in the VFS.
  	 *
  	 * The regular truncate() case without ATTR_CTIME and ATTR_MTIME is a
  	 * special case where we need to update the times despite not having
  	 * these flags set.  For all other operations the VFS set these flags
  	 * explicitly if it wants a timestamp update.
  	 */
  	if (newsize != oldsize &&
  	    !(iattr->ia_valid & (ATTR_CTIME | ATTR_MTIME))) {
  		iattr->ia_ctime = iattr->ia_mtime =
  			current_time(inode);
  		iattr->ia_valid |= ATTR_CTIME | ATTR_MTIME;
  	}
  
  	/*
  	 * The first thing we do is set the size to new_size permanently on
  	 * disk.  This way we don't have to worry about anyone ever being able
  	 * to look at the data being freed even in the face of a crash.
  	 * What we're getting around here is the case where we free a block, it
  	 * is allocated to another file, it is written to, and then we crash.
  	 * If the new data gets written to the file but the log buffers
  	 * containing the free and reallocation don't, then we'd end up with
  	 * garbage in the blocks being freed.  As long as we make the new size
  	 * permanent before actually freeing any blocks it doesn't matter if
  	 * they get written to.
  	 */
  	ip->i_disk_size = newsize;
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	if (newsize <= oldsize) {
  		error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK, newsize);
  		if (error)
  			goto out_trans_cancel;
  
  		/*
  		 * Truncated "down", so we're removing references to old data
  		 * here - if we delay flushing for a long time, we expose
  		 * ourselves unduly to the notorious NULL files problem.  So,
  		 * we mark this inode and flush it when the file is closed,
  		 * and do not wait the usual (long) time for writeout.
  		 */
  		xfs_iflags_set(ip, XFS_ITRUNCATED);
  
  		/* A truncate down always removes post-EOF blocks. */
  		xfs_inode_clear_eofblocks_tag(ip);
  	}
  
  	if (iattr->ia_valid & ATTR_MODE)
  		xfs_setattr_mode(ip, iattr);
  	if (iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME))
  		xfs_setattr_time(ip, iattr);
  
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	XFS_STATS_INC(mp, xs_ig_attrchg);
  
  	if (xfs_has_wsync(mp))
  		xfs_trans_set_sync(tp);
  
  	error = xfs_trans_commit(tp);
  out_unlock:
  	if (lock_flags)
  		xfs_iunlock(ip, lock_flags);
  	return error;
  
  out_trans_cancel:
  	xfs_trans_cancel(tp);
  	goto out_unlock;
  }
  
  int
  xfs_vn_setattr_size(
  	struct user_namespace	*mnt_userns,
  	struct dentry		*dentry,
  	struct iattr		*iattr)
  {
  	struct xfs_inode	*ip = XFS_I(d_inode(dentry));
  	int error;
  
  	trace_xfs_setattr(ip);
  
  	error = xfs_vn_change_ok(mnt_userns, dentry, iattr);
  	if (error)
  		return error;
  	return xfs_setattr_size(mnt_userns, ip, iattr);
  }
  
  STATIC int
  xfs_vn_setattr(
  	struct user_namespace	*mnt_userns,
  	struct dentry		*dentry,
  	struct iattr		*iattr)
  {
  	struct inode		*inode = d_inode(dentry);
  	struct xfs_inode	*ip = XFS_I(inode);
  	int			error;
  
  	if (iattr->ia_valid & ATTR_SIZE) {
  		uint			iolock;
  
  		xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
  		iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
  
  		error = xfs_break_layouts(inode, &iolock, BREAK_UNMAP);
  		if (error) {
  			xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
  			return error;
  		}
  
  		error = xfs_vn_setattr_size(mnt_userns, dentry, iattr);
  		xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
  	} else {
  		trace_xfs_setattr(ip);
  
  		error = xfs_vn_change_ok(mnt_userns, dentry, iattr);
  		if (!error)
  			error = xfs_setattr_nonsize(mnt_userns, ip, iattr);
  	}
  
  	return error;
  }
  
  STATIC int
  xfs_vn_update_time(
  	struct inode		*inode,
  	struct timespec64	*now,
  	int			flags)
  {
  	struct xfs_inode	*ip = XFS_I(inode);
  	struct xfs_mount	*mp = ip->i_mount;
  	int			log_flags = XFS_ILOG_TIMESTAMP;
  	struct xfs_trans	*tp;
  	int			error;
  
  	trace_xfs_update_time(ip);
  
  	if (inode->i_sb->s_flags & SB_LAZYTIME) {
  		if (!((flags & S_VERSION) &&
  		      inode_maybe_inc_iversion(inode, false)))
  			return generic_update_time(inode, now, flags);
  
  		/* Capture the iversion update that just occurred */
  		log_flags |= XFS_ILOG_CORE;
  	}
  
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
  	if (error)
  		return error;
  
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	if (flags & S_CTIME)
  		inode->i_ctime = *now;
  	if (flags & S_MTIME)
  		inode->i_mtime = *now;
  	if (flags & S_ATIME)
  		inode->i_atime = *now;
  
  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
  	xfs_trans_log_inode(tp, ip, log_flags);
  	return xfs_trans_commit(tp);
  }
  
  STATIC int
  xfs_vn_fiemap(
  	struct inode		*inode,
  	struct fiemap_extent_info *fieinfo,
  	u64			start,
  	u64			length)
  {
  	int			error;
  
  	xfs_ilock(XFS_I(inode), XFS_IOLOCK_SHARED);
  	if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
  		fieinfo->fi_flags &= ~FIEMAP_FLAG_XATTR;
  		error = iomap_fiemap(inode, fieinfo, start, length,
  				&xfs_xattr_iomap_ops);
  	} else {
  		error = iomap_fiemap(inode, fieinfo, start, length,
  				&xfs_read_iomap_ops);
  	}
  	xfs_iunlock(XFS_I(inode), XFS_IOLOCK_SHARED);
  
  	return error;
  }
  
  STATIC int
  xfs_vn_tmpfile(
  	struct user_namespace	*mnt_userns,
  	struct inode		*dir,
  	struct dentry		*dentry,
  	umode_t			mode)
  {
  	return xfs_generic_create(mnt_userns, dir, dentry, mode, 0, true);
  }
  
  static const struct inode_operations xfs_inode_operations = {
  	.get_acl		= xfs_get_acl,
  	.set_acl		= xfs_set_acl,
  	.getattr		= xfs_vn_getattr,
  	.setattr		= xfs_vn_setattr,
  	.listxattr		= xfs_vn_listxattr,
  	.fiemap			= xfs_vn_fiemap,
  	.update_time		= xfs_vn_update_time,
  	.fileattr_get		= xfs_fileattr_get,
  	.fileattr_set		= xfs_fileattr_set,
  };
  
  static const struct inode_operations xfs_dir_inode_operations = {
  	.create			= xfs_vn_create,
  	.lookup			= xfs_vn_lookup,
  	.link			= xfs_vn_link,
  	.unlink			= xfs_vn_unlink,
  	.symlink		= xfs_vn_symlink,
  	.mkdir			= xfs_vn_mkdir,
  	/*
  	 * Yes, XFS uses the same method for rmdir and unlink.
  	 *
  	 * There are some subtile differences deeper in the code,
  	 * but we use S_ISDIR to check for those.
  	 */
  	.rmdir			= xfs_vn_unlink,
  	.mknod			= xfs_vn_mknod,
  	.rename			= xfs_vn_rename,
  	.get_acl		= xfs_get_acl,
  	.set_acl		= xfs_set_acl,
  	.getattr		= xfs_vn_getattr,
  	.setattr		= xfs_vn_setattr,
  	.listxattr		= xfs_vn_listxattr,
  	.update_time		= xfs_vn_update_time,
  	.tmpfile		= xfs_vn_tmpfile,
  	.fileattr_get		= xfs_fileattr_get,
  	.fileattr_set		= xfs_fileattr_set,
  };
  
  static const struct inode_operations xfs_dir_ci_inode_operations = {
  	.create			= xfs_vn_create,
  	.lookup			= xfs_vn_ci_lookup,
  	.link			= xfs_vn_link,
  	.unlink			= xfs_vn_unlink,
  	.symlink		= xfs_vn_symlink,
  	.mkdir			= xfs_vn_mkdir,
  	/*
  	 * Yes, XFS uses the same method for rmdir and unlink.
  	 *
  	 * There are some subtile differences deeper in the code,
  	 * but we use S_ISDIR to check for those.
  	 */
  	.rmdir			= xfs_vn_unlink,
  	.mknod			= xfs_vn_mknod,
  	.rename			= xfs_vn_rename,
  	.get_acl		= xfs_get_acl,
  	.set_acl		= xfs_set_acl,
  	.getattr		= xfs_vn_getattr,
  	.setattr		= xfs_vn_setattr,
  	.listxattr		= xfs_vn_listxattr,
  	.update_time		= xfs_vn_update_time,
  	.tmpfile		= xfs_vn_tmpfile,
  	.fileattr_get		= xfs_fileattr_get,
  	.fileattr_set		= xfs_fileattr_set,
  };
  
  static const struct inode_operations xfs_symlink_inode_operations = {
  	.get_link		= xfs_vn_get_link,
  	.getattr		= xfs_vn_getattr,
  	.setattr		= xfs_vn_setattr,
  	.listxattr		= xfs_vn_listxattr,
  	.update_time		= xfs_vn_update_time,
  };
  
  /* Figure out if this file actually supports DAX. */
  static bool
  xfs_inode_supports_dax(
  	struct xfs_inode	*ip)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  
  	/* Only supported on regular files. */
  	if (!S_ISREG(VFS_I(ip)->i_mode))
  		return false;
  
  	/* Only supported on non-reflinked files. */
  	if (xfs_is_reflink_inode(ip))
  		return false;
  
  	/* Block size must match page size */
  	if (mp->m_sb.sb_blocksize != PAGE_SIZE)
  		return false;
  
  	/* Device has to support DAX too. */
  	return xfs_inode_buftarg(ip)->bt_daxdev != NULL;
  }
  
  static bool
  xfs_inode_should_enable_dax(
  	struct xfs_inode *ip)
  {
  	if (!IS_ENABLED(CONFIG_FS_DAX))
  		return false;
  	if (xfs_has_dax_never(ip->i_mount))
  		return false;
  	if (!xfs_inode_supports_dax(ip))
  		return false;
  	if (xfs_has_dax_always(ip->i_mount))
  		return true;
  	if (ip->i_diflags2 & XFS_DIFLAG2_DAX)
  		return true;
  	return false;
  }
  
  void
  xfs_diflags_to_iflags(
  	struct xfs_inode	*ip,
  	bool init)
  {
  	struct inode            *inode = VFS_I(ip);
  	unsigned int            xflags = xfs_ip2xflags(ip);
  	unsigned int            flags = 0;
  
  	ASSERT(!(IS_DAX(inode) && init));
  
  	if (xflags & FS_XFLAG_IMMUTABLE)
  		flags |= S_IMMUTABLE;
  	if (xflags & FS_XFLAG_APPEND)
  		flags |= S_APPEND;
  	if (xflags & FS_XFLAG_SYNC)
  		flags |= S_SYNC;
  	if (xflags & FS_XFLAG_NOATIME)
  		flags |= S_NOATIME;
  	if (init && xfs_inode_should_enable_dax(ip))
  		flags |= S_DAX;
  
  	/*
  	 * S_DAX can only be set during inode initialization and is never set by
  	 * the VFS, so we cannot mask off S_DAX in i_flags.
  	 */
  	inode->i_flags &= ~(S_IMMUTABLE | S_APPEND | S_SYNC | S_NOATIME);
  	inode->i_flags |= flags;
  }
  
  /*
   * Initialize the Linux inode.
   *
   * When reading existing inodes from disk this is called directly from xfs_iget,
   * when creating a new inode it is called from xfs_init_new_inode after setting
   * up the inode. These callers have different criteria for clearing XFS_INEW, so
   * leave it up to the caller to deal with unlocking the inode appropriately.
   */
  void
  xfs_setup_inode(
  	struct xfs_inode	*ip)
  {
  	struct inode		*inode = &ip->i_vnode;
  	gfp_t			gfp_mask;
  
  	inode->i_ino = ip->i_ino;
  	inode->i_state |= I_NEW;
  
  	inode_sb_list_add(inode);
  	/* make the inode look hashed for the writeback code */
  	inode_fake_hash(inode);
  
  	i_size_write(inode, ip->i_disk_size);
  	xfs_diflags_to_iflags(ip, true);
  
  	if (S_ISDIR(inode->i_mode)) {
  		/*
  		 * We set the i_rwsem class here to avoid potential races with
  		 * lockdep_annotate_inode_mutex_key() reinitialising the lock
  		 * after a filehandle lookup has already found the inode in
  		 * cache before it has been unlocked via unlock_new_inode().
  		 */
  		lockdep_set_class(&inode->i_rwsem,
  				  &inode->i_sb->s_type->i_mutex_dir_key);
  		lockdep_set_class(&ip->i_lock.mr_lock, &xfs_dir_ilock_class);
  	} else {
  		lockdep_set_class(&ip->i_lock.mr_lock, &xfs_nondir_ilock_class);
  	}
  
  	/*
  	 * Ensure all page cache allocations are done from GFP_NOFS context to
  	 * prevent direct reclaim recursion back into the filesystem and blowing
  	 * stacks or deadlocking.
  	 */
  	gfp_mask = mapping_gfp_mask(inode->i_mapping);
  	mapping_set_gfp_mask(inode->i_mapping, (gfp_mask & ~(__GFP_FS)));
  
  	/*
  	 * If there is no attribute fork no ACL can exist on this inode,
  	 * and it can't have any file capabilities attached to it either.
  	 */
  	if (!XFS_IFORK_Q(ip)) {
  		inode_has_no_xattr(inode);
  		cache_no_acl(inode);
  	}
  }
  
  void
  xfs_setup_iops(
  	struct xfs_inode	*ip)
  {
  	struct inode		*inode = &ip->i_vnode;
  
  	switch (inode->i_mode & S_IFMT) {
  	case S_IFREG:
  		inode->i_op = &xfs_inode_operations;
  		inode->i_fop = &xfs_file_operations;
  		if (IS_DAX(inode))
  			inode->i_mapping->a_ops = &xfs_dax_aops;
  		else
  			inode->i_mapping->a_ops = &xfs_address_space_operations;
  		break;
  	case S_IFDIR:
  		if (xfs_has_asciici(XFS_M(inode->i_sb)))
  			inode->i_op = &xfs_dir_ci_inode_operations;
  		else
  			inode->i_op = &xfs_dir_inode_operations;
  		inode->i_fop = &xfs_dir_file_operations;
  		break;
  	case S_IFLNK:
  		inode->i_op = &xfs_symlink_inode_operations;
  		break;
  	default:
  		inode->i_op = &xfs_inode_operations;
  		init_special_inode(inode, inode->i_mode, inode->i_rdev);
  		break;
  	}
  }
  