1 files changed, 952 insertions, 0 deletions

diff --git a/fs/xfs/xfs_handle.c b/fs/xfs/xfs_handle.c
new file mode 100644
index 000000000000..c8785ed59543
--- /dev/null
+++ b/fs/xfs/xfs_handle.c
@@ -0,0 +1,952 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * Copyright (c) 2022-2024 Oracle.
+ * All rights reserved.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_shared.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_inode.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_trans.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_attr.h"
+#include "xfs_ioctl.h"
+#include "xfs_parent.h"
+#include "xfs_da_btree.h"
+#include "xfs_handle.h"
+#include "xfs_health.h"
+#include "xfs_icache.h"
+#include "xfs_export.h"
+#include "xfs_xattr.h"
+#include "xfs_acl.h"
+
+#include <linux/namei.h>
+
+static inline size_t
+xfs_filehandle_fid_len(void)
+{
+	struct xfs_handle	*handle = NULL;
+
+	return sizeof(struct xfs_fid) - sizeof(handle->ha_fid.fid_len);
+}
+
+static inline size_t
+xfs_filehandle_init(
+	struct xfs_mount	*mp,
+	xfs_ino_t		ino,
+	uint32_t		gen,
+	struct xfs_handle	*handle)
+{
+	memcpy(&handle->ha_fsid, mp->m_fixedfsid, sizeof(struct xfs_fsid));
+
+	handle->ha_fid.fid_len = xfs_filehandle_fid_len();
+	handle->ha_fid.fid_pad = 0;
+	handle->ha_fid.fid_gen = gen;
+	handle->ha_fid.fid_ino = ino;
+
+	return sizeof(struct xfs_handle);
+}
+
+static inline size_t
+xfs_fshandle_init(
+	struct xfs_mount	*mp,
+	struct xfs_handle	*handle)
+{
+	memcpy(&handle->ha_fsid, mp->m_fixedfsid, sizeof(struct xfs_fsid));
+	memset(&handle->ha_fid, 0, sizeof(handle->ha_fid));
+
+	return sizeof(struct xfs_fsid);
+}
+
+/*
+ * xfs_find_handle maps from userspace xfs_fsop_handlereq structure to
+ * a file or fs handle.
+ *
+ * XFS_IOC_PATH_TO_FSHANDLE
+ *    returns fs handle for a mount point or path within that mount point
+ * XFS_IOC_FD_TO_HANDLE
+ *    returns full handle for a FD opened in user space
+ * XFS_IOC_PATH_TO_HANDLE
+ *    returns full handle for a path
+ */
+int
+xfs_find_handle(
+	unsigned int		cmd,
+	xfs_fsop_handlereq_t	*hreq)
+{
+	int			hsize;
+	xfs_handle_t		handle;
+	struct inode		*inode;
+	struct fd		f = {NULL};
+	struct path		path;
+	int			error;
+	struct xfs_inode	*ip;
+
+	if (cmd == XFS_IOC_FD_TO_HANDLE) {
+		f = fdget(hreq->fd);
+		if (!f.file)
+			return -EBADF;
+		inode = file_inode(f.file);
+	} else {
+		error = user_path_at(AT_FDCWD, hreq->path, 0, &path);
+		if (error)
+			return error;
+		inode = d_inode(path.dentry);
+	}
+	ip = XFS_I(inode);
+
+	/*
+	 * We can only generate handles for inodes residing on a XFS filesystem,
+	 * and only for regular files, directories or symbolic links.
+	 */
+	error = -EINVAL;
+	if (inode->i_sb->s_magic != XFS_SB_MAGIC)
+		goto out_put;
+
+	error = -EBADF;
+	if (!S_ISREG(inode->i_mode) &&
+	    !S_ISDIR(inode->i_mode) &&
+	    !S_ISLNK(inode->i_mode))
+		goto out_put;
+
+
+	memcpy(&handle.ha_fsid, ip->i_mount->m_fixedfsid, sizeof(xfs_fsid_t));
+
+	if (cmd == XFS_IOC_PATH_TO_FSHANDLE)
+		hsize = xfs_fshandle_init(ip->i_mount, &handle);
+	else
+		hsize = xfs_filehandle_init(ip->i_mount, ip->i_ino,
+				inode->i_generation, &handle);
+
+	error = -EFAULT;
+	if (copy_to_user(hreq->ohandle, &handle, hsize) ||
+	    copy_to_user(hreq->ohandlen, &hsize, sizeof(__s32)))
+		goto out_put;
+
+	error = 0;
+
+ out_put:
+	if (cmd == XFS_IOC_FD_TO_HANDLE)
+		fdput(f);
+	else
+		path_put(&path);
+	return error;
+}
+
+/*
+ * No need to do permission checks on the various pathname components
+ * as the handle operations are privileged.
+ */
+STATIC int
+xfs_handle_acceptable(
+	void			*context,
+	struct dentry		*dentry)
+{
+	return 1;
+}
+
+/* Convert handle already copied to kernel space into a dentry. */
+static struct dentry *
+xfs_khandle_to_dentry(
+	struct file		*file,
+	struct xfs_handle	*handle)
+{
+	struct xfs_fid64        fid = {
+		.ino		= handle->ha_fid.fid_ino,
+		.gen		= handle->ha_fid.fid_gen,
+	};
+
+	/*
+	 * Only allow handle opens under a directory.
+	 */
+	if (!S_ISDIR(file_inode(file)->i_mode))
+		return ERR_PTR(-ENOTDIR);
+
+	if (handle->ha_fid.fid_len != xfs_filehandle_fid_len())
+		return ERR_PTR(-EINVAL);
+
+	return exportfs_decode_fh(file->f_path.mnt, (struct fid *)&fid, 3,
+			FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG,
+			xfs_handle_acceptable, NULL);
+}
+
+/* Convert handle already copied to kernel space into an xfs_inode. */
+static struct xfs_inode *
+xfs_khandle_to_inode(
+	struct file		*file,
+	struct xfs_handle	*handle)
+{
+	struct xfs_inode	*ip = XFS_I(file_inode(file));
+	struct xfs_mount	*mp = ip->i_mount;
+	struct inode		*inode;
+
+	if (!S_ISDIR(VFS_I(ip)->i_mode))
+		return ERR_PTR(-ENOTDIR);
+
+	if (handle->ha_fid.fid_len != xfs_filehandle_fid_len())
+		return ERR_PTR(-EINVAL);
+
+	inode = xfs_nfs_get_inode(mp->m_super, handle->ha_fid.fid_ino,
+			handle->ha_fid.fid_gen);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+
+	return XFS_I(inode);
+}
+
+/*
+ * Convert userspace handle data into a dentry.
+ */
+struct dentry *
+xfs_handle_to_dentry(
+	struct file		*parfilp,
+	void __user		*uhandle,
+	u32			hlen)
+{
+	xfs_handle_t		handle;
+
+	if (hlen != sizeof(xfs_handle_t))
+		return ERR_PTR(-EINVAL);
+	if (copy_from_user(&handle, uhandle, hlen))
+		return ERR_PTR(-EFAULT);
+
+	return xfs_khandle_to_dentry(parfilp, &handle);
+}
+
+STATIC struct dentry *
+xfs_handlereq_to_dentry(
+	struct file		*parfilp,
+	xfs_fsop_handlereq_t	*hreq)
+{
+	return xfs_handle_to_dentry(parfilp, hreq->ihandle, hreq->ihandlen);
+}
+
+int
+xfs_open_by_handle(
+	struct file		*parfilp,
+	xfs_fsop_handlereq_t	*hreq)
+{
+	const struct cred	*cred = current_cred();
+	int			error;
+	int			fd;
+	int			permflag;
+	struct file		*filp;
+	struct inode		*inode;
+	struct dentry		*dentry;
+	fmode_t			fmode;
+	struct path		path;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	dentry = xfs_handlereq_to_dentry(parfilp, hreq);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+	inode = d_inode(dentry);
+
+	/* Restrict xfs_open_by_handle to directories & regular files. */
+	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) {
+		error = -EPERM;
+		goto out_dput;
+	}
+
+#if BITS_PER_LONG != 32
+	hreq->oflags |= O_LARGEFILE;
+#endif
+
+	permflag = hreq->oflags;
+	fmode = OPEN_FMODE(permflag);
+	if ((!(permflag & O_APPEND) || (permflag & O_TRUNC)) &&
+	    (fmode & FMODE_WRITE) && IS_APPEND(inode)) {
+		error = -EPERM;
+		goto out_dput;
+	}
+
+	if ((fmode & FMODE_WRITE) && IS_IMMUTABLE(inode)) {
+		error = -EPERM;
+		goto out_dput;
+	}
+
+	/* Can't write directories. */
+	if (S_ISDIR(inode->i_mode) && (fmode & FMODE_WRITE)) {
+		error = -EISDIR;
+		goto out_dput;
+	}
+
+	fd = get_unused_fd_flags(0);
+	if (fd < 0) {
+		error = fd;
+		goto out_dput;
+	}
+
+	path.mnt = parfilp->f_path.mnt;
+	path.dentry = dentry;
+	filp = dentry_open(&path, hreq->oflags, cred);
+	dput(dentry);
+	if (IS_ERR(filp)) {
+		put_unused_fd(fd);
+		return PTR_ERR(filp);
+	}
+
+	if (S_ISREG(inode->i_mode)) {
+		filp->f_flags |= O_NOATIME;
+		filp->f_mode |= FMODE_NOCMTIME;
+	}
+
+	fd_install(fd, filp);
+	return fd;
+
+ out_dput:
+	dput(dentry);
+	return error;
+}
+
+int
+xfs_readlink_by_handle(
+	struct file		*parfilp,
+	xfs_fsop_handlereq_t	*hreq)
+{
+	struct dentry		*dentry;
+	__u32			olen;
+	int			error;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	dentry = xfs_handlereq_to_dentry(parfilp, hreq);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	/* Restrict this handle operation to symlinks only. */
+	if (!d_is_symlink(dentry)) {
+		error = -EINVAL;
+		goto out_dput;
+	}
+
+	if (copy_from_user(&olen, hreq->ohandlen, sizeof(__u32))) {
+		error = -EFAULT;
+		goto out_dput;
+	}
+
+	error = vfs_readlink(dentry, hreq->ohandle, olen);
+
+ out_dput:
+	dput(dentry);
+	return error;
+}
+
+/*
+ * Format an attribute and copy it out to the user's buffer.
+ * Take care to check values and protect against them changing later,
+ * we may be reading them directly out of a user buffer.
+ */
+static void
+xfs_ioc_attr_put_listent(
+	struct xfs_attr_list_context *context,
+	int			flags,
+	unsigned char		*name,
+	int			namelen,
+	void			*value,
+	int			valuelen)
+{
+	struct xfs_attrlist	*alist = context->buffer;
+	struct xfs_attrlist_ent	*aep;
+	int			arraytop;
+
+	ASSERT(!context->seen_enough);
+	ASSERT(context->count >= 0);
+	ASSERT(context->count < (ATTR_MAX_VALUELEN/8));
+	ASSERT(context->firstu >= sizeof(*alist));
+	ASSERT(context->firstu <= context->bufsize);
+
+	/*
+	 * Only list entries in the right namespace.
+	 */
+	if (context->attr_filter != (flags & XFS_ATTR_NSP_ONDISK_MASK))
+		return;
+
+	arraytop = sizeof(*alist) +
+			context->count * sizeof(alist->al_offset[0]);
+
+	/* decrement by the actual bytes used by the attr */
+	context->firstu -= round_up(offsetof(struct xfs_attrlist_ent, a_name) +
+			namelen + 1, sizeof(uint32_t));
+	if (context->firstu < arraytop) {
+		trace_xfs_attr_list_full(context);
+		alist->al_more = 1;
+		context->seen_enough = 1;
+		return;
+	}
+
+	aep = context->buffer + context->firstu;
+	aep->a_valuelen = valuelen;
+	memcpy(aep->a_name, name, namelen);
+	aep->a_name[namelen] = 0;
+	alist->al_offset[context->count++] = context->firstu;
+	alist->al_count = context->count;
+	trace_xfs_attr_list_add(context);
+}
+
+static unsigned int
+xfs_attr_filter(
+	u32			ioc_flags)
+{
+	if (ioc_flags & XFS_IOC_ATTR_ROOT)
+		return XFS_ATTR_ROOT;
+	if (ioc_flags & XFS_IOC_ATTR_SECURE)
+		return XFS_ATTR_SECURE;
+	return 0;
+}
+
+static inline enum xfs_attr_update
+xfs_xattr_flags(
+	u32			ioc_flags,
+	void			*value)
+{
+	if (!value)
+		return XFS_ATTRUPDATE_REMOVE;
+	if (ioc_flags & XFS_IOC_ATTR_CREATE)
+		return XFS_ATTRUPDATE_CREATE;
+	if (ioc_flags & XFS_IOC_ATTR_REPLACE)
+		return XFS_ATTRUPDATE_REPLACE;
+	return XFS_ATTRUPDATE_UPSERT;
+}
+
+int
+xfs_ioc_attr_list(
+	struct xfs_inode		*dp,
+	void __user			*ubuf,
+	size_t				bufsize,
+	int				flags,
+	struct xfs_attrlist_cursor __user *ucursor)
+{
+	struct xfs_attr_list_context	context = { };
+	struct xfs_attrlist		*alist;
+	void				*buffer;
+	int				error;
+
+	if (bufsize < sizeof(struct xfs_attrlist) ||
+	    bufsize > XFS_XATTR_LIST_MAX)
+		return -EINVAL;
+
+	/*
+	 * Reject flags, only allow namespaces.
+	 */
+	if (flags & ~(XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE))
+		return -EINVAL;
+	if (flags == (XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE))
+		return -EINVAL;
+
+	/*
+	 * Validate the cursor.
+	 */
+	if (copy_from_user(&context.cursor, ucursor, sizeof(context.cursor)))
+		return -EFAULT;
+	if (context.cursor.pad1 || context.cursor.pad2)
+		return -EINVAL;
+	if (!context.cursor.initted &&
+	    (context.cursor.hashval || context.cursor.blkno ||
+	     context.cursor.offset))
+		return -EINVAL;
+
+	buffer = kvzalloc(bufsize, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	/*
+	 * Initialize the output buffer.
+	 */
+	context.dp = dp;
+	context.resynch = 1;
+	context.attr_filter = xfs_attr_filter(flags);
+	context.buffer = buffer;
+	context.bufsize = round_down(bufsize, sizeof(uint32_t));
+	context.firstu = context.bufsize;
+	context.put_listent = xfs_ioc_attr_put_listent;
+
+	alist = context.buffer;
+	alist->al_count = 0;
+	alist->al_more = 0;
+	alist->al_offset[0] = context.bufsize;
+
+	error = xfs_attr_list(&context);
+	if (error)
+		goto out_free;
+
+	if (copy_to_user(ubuf, buffer, bufsize) ||
+	    copy_to_user(ucursor, &context.cursor, sizeof(context.cursor)))
+		error = -EFAULT;
+out_free:
+	kvfree(buffer);
+	return error;
+}
+
+int
+xfs_attrlist_by_handle(
+	struct file		*parfilp,
+	struct xfs_fsop_attrlist_handlereq __user *p)
+{
+	struct xfs_fsop_attrlist_handlereq al_hreq;
+	struct dentry		*dentry;
+	int			error = -ENOMEM;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	if (copy_from_user(&al_hreq, p, sizeof(al_hreq)))
+		return -EFAULT;
+
+	dentry = xfs_handlereq_to_dentry(parfilp, &al_hreq.hreq);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	error = xfs_ioc_attr_list(XFS_I(d_inode(dentry)), al_hreq.buffer,
+				  al_hreq.buflen, al_hreq.flags, &p->pos);
+	dput(dentry);
+	return error;
+}
+
+static int
+xfs_attrmulti_attr_get(
+	struct inode		*inode,
+	unsigned char		*name,
+	unsigned char		__user *ubuf,
+	uint32_t		*len,
+	uint32_t		flags)
+{
+	struct xfs_da_args	args = {
+		.dp		= XFS_I(inode),
+		.attr_filter	= xfs_attr_filter(flags),
+		.name		= name,
+		.namelen	= strlen(name),
+		.valuelen	= *len,
+	};
+	int			error;
+
+	if (*len > XFS_XATTR_SIZE_MAX)
+		return -EINVAL;
+
+	error = xfs_attr_get(&args);
+	if (error)
+		goto out_kfree;
+
+	*len = args.valuelen;
+	if (copy_to_user(ubuf, args.value, args.valuelen))
+		error = -EFAULT;
+
+out_kfree:
+	kvfree(args.value);
+	return error;
+}
+
+static int
+xfs_attrmulti_attr_set(
+	struct inode		*inode,
+	unsigned char		*name,
+	const unsigned char	__user *ubuf,
+	uint32_t		len,
+	uint32_t		flags)
+{
+	struct xfs_da_args	args = {
+		.dp		= XFS_I(inode),
+		.attr_filter	= xfs_attr_filter(flags),
+		.name		= name,
+		.namelen	= strlen(name),
+	};
+	int			error;
+
+	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+		return -EPERM;
+
+	if (ubuf) {
+		if (len > XFS_XATTR_SIZE_MAX)
+			return -EINVAL;
+		args.value = memdup_user(ubuf, len);
+		if (IS_ERR(args.value))
+			return PTR_ERR(args.value);
+		args.valuelen = len;
+	}
+
+	error = xfs_attr_change(&args, xfs_xattr_flags(flags, args.value));
+	if (!error && (flags & XFS_IOC_ATTR_ROOT))
+		xfs_forget_acl(inode, name);
+	kfree(args.value);
+	return error;
+}
+
+int
+xfs_ioc_attrmulti_one(
+	struct file		*parfilp,
+	struct inode		*inode,
+	uint32_t		opcode,
+	void __user		*uname,
+	void __user		*value,
+	uint32_t		*len,
+	uint32_t		flags)
+{
+	unsigned char		*name;
+	int			error;
+
+	if ((flags & XFS_IOC_ATTR_ROOT) && (flags & XFS_IOC_ATTR_SECURE))
+		return -EINVAL;
+
+	name = strndup_user(uname, MAXNAMELEN);
+	if (IS_ERR(name))
+		return PTR_ERR(name);
+
+	switch (opcode) {
+	case ATTR_OP_GET:
+		error = xfs_attrmulti_attr_get(inode, name, value, len, flags);
+		break;
+	case ATTR_OP_REMOVE:
+		value = NULL;
+		*len = 0;
+		fallthrough;
+	case ATTR_OP_SET:
+		error = mnt_want_write_file(parfilp);
+		if (error)
+			break;
+		error = xfs_attrmulti_attr_set(inode, name, value, *len, flags);
+		mnt_drop_write_file(parfilp);
+		break;
+	default:
+		error = -EINVAL;
+		break;
+	}
+
+	kfree(name);
+	return error;
+}
+
+int
+xfs_attrmulti_by_handle(
+	struct file		*parfilp,
+	void			__user *arg)
+{
+	int			error;
+	xfs_attr_multiop_t	*ops;
+	xfs_fsop_attrmulti_handlereq_t am_hreq;
+	struct dentry		*dentry;
+	unsigned int		i, size;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	if (copy_from_user(&am_hreq, arg, sizeof(xfs_fsop_attrmulti_handlereq_t)))
+		return -EFAULT;
+
+	/* overflow check */
+	if (am_hreq.opcount >= INT_MAX / sizeof(xfs_attr_multiop_t))
+		return -E2BIG;
+
+	dentry = xfs_handlereq_to_dentry(parfilp, &am_hreq.hreq);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	error = -E2BIG;
+	size = am_hreq.opcount * sizeof(xfs_attr_multiop_t);
+	if (!size || size > 16 * PAGE_SIZE)
+		goto out_dput;
+
+	ops = memdup_user(am_hreq.ops, size);
+	if (IS_ERR(ops)) {
+		error = PTR_ERR(ops);
+		goto out_dput;
+	}
+
+	error = 0;
+	for (i = 0; i < am_hreq.opcount; i++) {
+		ops[i].am_error = xfs_ioc_attrmulti_one(parfilp,
+				d_inode(dentry), ops[i].am_opcode,
+				ops[i].am_attrname, ops[i].am_attrvalue,
+				&ops[i].am_length, ops[i].am_flags);
+	}
+
+	if (copy_to_user(am_hreq.ops, ops, size))
+		error = -EFAULT;
+
+	kfree(ops);
+ out_dput:
+	dput(dentry);
+	return error;
+}
+
+struct xfs_getparents_ctx {
+	struct xfs_attr_list_context	context;
+	struct xfs_getparents_by_handle	gph;
+
+	/* File to target */
+	struct xfs_inode		*ip;
+
+	/* Internal buffer where we format records */
+	void				*krecords;
+
+	/* Last record filled out */
+	struct xfs_getparents_rec	*lastrec;
+
+	unsigned int			count;
+};
+
+static inline unsigned int
+xfs_getparents_rec_sizeof(
+	unsigned int		namelen)
+{
+	return round_up(sizeof(struct xfs_getparents_rec) + namelen + 1,
+			sizeof(uint64_t));
+}
+
+static void
+xfs_getparents_put_listent(
+	struct xfs_attr_list_context	*context,
+	int				flags,
+	unsigned char			*name,
+	int				namelen,
+	void				*value,
+	int				valuelen)
+{
+	struct xfs_getparents_ctx	*gpx =
+		container_of(context, struct xfs_getparents_ctx, context);
+	struct xfs_inode		*ip = context->dp;
+	struct xfs_mount		*mp = ip->i_mount;
+	struct xfs_getparents		*gp = &gpx->gph.gph_request;
+	struct xfs_getparents_rec	*gpr = gpx->krecords + context->firstu;
+	unsigned short			reclen =
+		xfs_getparents_rec_sizeof(namelen);
+	xfs_ino_t			ino;
+	uint32_t			gen;
+	int				error;
+
+	if (!(flags & XFS_ATTR_PARENT))
+		return;
+
+	error = xfs_parent_from_attr(mp, flags, name, namelen, value, valuelen,
+			&ino, &gen);
+	if (error) {
+		xfs_inode_mark_sick(ip, XFS_SICK_INO_PARENT);
+		context->seen_enough = -EFSCORRUPTED;
+		return;
+	}
+
+	/*
+	 * We found a parent pointer, but we've filled up the buffer.  Signal
+	 * to the caller that we did /not/ reach the end of the parent pointer
+	 * recordset.
+	 */
+	if (context->firstu > context->bufsize - reclen) {
+		context->seen_enough = 1;
+		return;
+	}
+
+	/* Format the parent pointer directly into the caller buffer. */
+	gpr->gpr_reclen = reclen;
+	xfs_filehandle_init(mp, ino, gen, &gpr->gpr_parent);
+	memcpy(gpr->gpr_name, name, namelen);
+	gpr->gpr_name[namelen] = 0;
+
+	trace_xfs_getparents_put_listent(ip, gp, context, gpr);
+
+	context->firstu += reclen;
+	gpx->count++;
+	gpx->lastrec = gpr;
+}
+
+/* Expand the last record to fill the rest of the caller's buffer. */
+static inline void
+xfs_getparents_expand_lastrec(
+	struct xfs_getparents_ctx	*gpx)
+{
+	struct xfs_getparents		*gp = &gpx->gph.gph_request;
+	struct xfs_getparents_rec	*gpr = gpx->lastrec;
+
+	if (!gpx->lastrec)
+		gpr = gpx->krecords;
+
+	gpr->gpr_reclen = gp->gp_bufsize - ((void *)gpr - gpx->krecords);
+
+	trace_xfs_getparents_expand_lastrec(gpx->ip, gp, &gpx->context, gpr);
+}
+
+static inline void __user *u64_to_uptr(u64 val)
+{
+	return (void __user *)(uintptr_t)val;
+}
+
+/* Retrieve the parent pointers for a given inode. */
+STATIC int
+xfs_getparents(
+	struct xfs_getparents_ctx	*gpx)
+{
+	struct xfs_getparents		*gp = &gpx->gph.gph_request;
+	struct xfs_inode		*ip = gpx->ip;
+	struct xfs_mount		*mp = ip->i_mount;
+	size_t				bufsize;
+	int				error;
+
+	/* Check size of buffer requested by user */
+	if (gp->gp_bufsize > XFS_XATTR_LIST_MAX)
+		return -ENOMEM;
+	if (gp->gp_bufsize < xfs_getparents_rec_sizeof(1))
+		return -EINVAL;
+
+	if (gp->gp_iflags & ~XFS_GETPARENTS_IFLAGS_ALL)
+		return -EINVAL;
+	if (gp->gp_reserved)
+		return -EINVAL;
+
+	bufsize = round_down(gp->gp_bufsize, sizeof(uint64_t));
+	gpx->krecords = kvzalloc(bufsize, GFP_KERNEL);
+	if (!gpx->krecords) {
+		bufsize = min(bufsize, PAGE_SIZE);
+		gpx->krecords = kvzalloc(bufsize, GFP_KERNEL);
+		if (!gpx->krecords)
+			return -ENOMEM;
+	}
+
+	gpx->context.dp = ip;
+	gpx->context.resynch = 1;
+	gpx->context.put_listent = xfs_getparents_put_listent;
+	gpx->context.bufsize = bufsize;
+	/* firstu is used to track the bytes filled in the buffer */
+	gpx->context.firstu = 0;
+
+	/* Copy the cursor provided by caller */
+	memcpy(&gpx->context.cursor, &gp->gp_cursor,
+			sizeof(struct xfs_attrlist_cursor));
+	gpx->count = 0;
+	gp->gp_oflags = 0;
+
+	trace_xfs_getparents_begin(ip, gp, &gpx->context.cursor);
+
+	error = xfs_attr_list(&gpx->context);
+	if (error)
+		goto out_free_buf;
+	if (gpx->context.seen_enough < 0) {
+		error = gpx->context.seen_enough;
+		goto out_free_buf;
+	}
+	xfs_getparents_expand_lastrec(gpx);
+
+	/* Update the caller with the current cursor position */
+	memcpy(&gp->gp_cursor, &gpx->context.cursor,
+			sizeof(struct xfs_attrlist_cursor));
+
+	/* Is this the root directory? */
+	if (ip->i_ino == mp->m_sb.sb_rootino)
+		gp->gp_oflags |= XFS_GETPARENTS_OFLAG_ROOT;
+
+	if (gpx->context.seen_enough == 0) {
+		/*
+		 * If we did not run out of buffer space, then we reached the
+		 * end of the pptr recordset, so set the DONE flag.
+		 */
+		gp->gp_oflags |= XFS_GETPARENTS_OFLAG_DONE;
+	} else if (gpx->count == 0) {
+		/*
+		 * If we ran out of buffer space before copying any parent
+		 * pointers at all, the caller's buffer was too short.  Tell
+		 * userspace that, erm, the message is too long.
+		 */
+		error = -EMSGSIZE;
+		goto out_free_buf;
+	}
+
+	trace_xfs_getparents_end(ip, gp, &gpx->context.cursor);
+
+	ASSERT(gpx->context.firstu <= gpx->gph.gph_request.gp_bufsize);
+
+	/* Copy the records to userspace. */
+	if (copy_to_user(u64_to_uptr(gpx->gph.gph_request.gp_buffer),
+				gpx->krecords, gpx->context.firstu))
+		error = -EFAULT;
+
+out_free_buf:
+	kvfree(gpx->krecords);
+	gpx->krecords = NULL;
+	return error;
+}
+
+/* Retrieve the parents of this file and pass them back to userspace. */
+int
+xfs_ioc_getparents(
+	struct file			*file,
+	struct xfs_getparents __user	*ureq)
+{
+	struct xfs_getparents_ctx	gpx = {
+		.ip			= XFS_I(file_inode(file)),
+	};
+	struct xfs_getparents		*kreq = &gpx.gph.gph_request;
+	struct xfs_mount		*mp = gpx.ip->i_mount;
+	int				error;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	if (!xfs_has_parent(mp))
+		return -EOPNOTSUPP;
+	if (copy_from_user(kreq, ureq, sizeof(*kreq)))
+		return -EFAULT;
+
+	error = xfs_getparents(&gpx);
+	if (error)
+		return error;
+
+	if (copy_to_user(ureq, kreq, sizeof(*kreq)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/* Retrieve the parents of this file handle and pass them back to userspace. */
+int
+xfs_ioc_getparents_by_handle(
+	struct file			*file,
+	struct xfs_getparents_by_handle __user	*ureq)
+{
+	struct xfs_getparents_ctx	gpx = { };
+	struct xfs_inode		*ip = XFS_I(file_inode(file));
+	struct xfs_mount		*mp = ip->i_mount;
+	struct xfs_getparents_by_handle	*kreq = &gpx.gph;
+	struct xfs_handle		*handle = &kreq->gph_handle;
+	int				error;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	if (!xfs_has_parent(mp))
+		return -EOPNOTSUPP;
+	if (copy_from_user(kreq, ureq, sizeof(*kreq)))
+		return -EFAULT;
+
+	/*
+	 * We don't use exportfs_decode_fh because it does too much work here.
+	 * If the handle refers to a directory, the exportfs code will walk
+	 * upwards through the directory tree to connect the dentries to the
+	 * root directory dentry.  For GETPARENTS we don't care about that
+	 * because we're not actually going to open a file descriptor; we only
+	 * want to open an inode and read its parent pointers.
+	 *
+	 * Note that xfs_scrub uses GETPARENTS to log that it will try to fix a
+	 * corrupted file's metadata.  For this usecase we would really rather
+	 * userspace single-step the path reconstruction to avoid loops or
+	 * other strange things if the directory tree is corrupt.
+	 */
+	gpx.ip = xfs_khandle_to_inode(file, handle);
+	if (IS_ERR(gpx.ip))
+		return PTR_ERR(gpx.ip);
+
+	error = xfs_getparents(&gpx);
+	if (error)
+		goto out_rele;
+
+	if (copy_to_user(ureq, kreq, sizeof(*kreq)))
+		error = -EFAULT;
+
+out_rele:
+	xfs_irele(gpx.ip);
+	return error;
+}