[PATCH RESEND v2 18/18] xfs: Add parent pointer ioctl

Allison Henderson
2022-08-04T19:40:51Z

This patch adds a new file ioctl to retrieve the parent pointer of a
given inode

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
---
fs/xfs/Makefile | 1 +
fs/xfs/libxfs/xfs_fs.h | 57 ++++++++++++++++
fs/xfs/libxfs/xfs_parent.c | 10 +++
fs/xfs/libxfs/xfs_parent.h | 2 +
fs/xfs/xfs_ioctl.c | 95 +++++++++++++++++++++++++-
fs/xfs/xfs_ondisk.h | 4 ++
fs/xfs/xfs_parent_utils.c | 134 +++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_parent_utils.h | 22 ++++++
8 files changed, 323 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index caeea8d968ba..998658e40ab4 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -86,6 +86,7 @@ xfs-y += xfs_aops.o \
xfs_mount.o \
xfs_mru_cache.o \
xfs_pwork.o \
+ xfs_parent_utils.o \
xfs_reflink.o \
xfs_stats.o \
xfs_super.o \
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index b0b4d7a3aa15..ba6ec82a0272 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -574,6 +574,7 @@ typedef struct xfs_fsop_handlereq {
#define XFS_IOC_ATTR_SECURE 0x0008 /* use attrs in security namespace */
#define XFS_IOC_ATTR_CREATE 0x0010 /* fail if attr already exists */
#define XFS_IOC_ATTR_REPLACE 0x0020 /* fail if attr does not exist */
+#define XFS_IOC_ATTR_PARENT 0x0040 /* use attrs in parent namespace */

typedef struct xfs_attrlist_cursor {
__u32 opaque[4];
@@ -752,6 +753,61 @@ struct xfs_scrub_metadata {
XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED)
#define XFS_SCRUB_FLAGS_ALL (XFS_SCRUB_FLAGS_IN | XFS_SCRUB_FLAGS_OUT)

+#define XFS_PPTR_MAXNAMELEN 256
+
+/* return parents of the handle, not the open fd */
+#define XFS_PPTR_IFLAG_HANDLE (1U << 0)
+
+/* target was the root directory */
+#define XFS_PPTR_OFLAG_ROOT (1U << 1)
+
+/* Cursor is done iterating pptrs */
+#define XFS_PPTR_OFLAG_DONE (1U << 2)
+
+/* Get an inode parent pointer through ioctl */
+struct xfs_parent_ptr {
+ __u64 xpp_ino; /* Inode */
+ __u32 xpp_gen; /* Inode generation */
+ __u32 xpp_diroffset; /* Directory offset */
+ __u32 xpp_namelen; /* File name length */
+ __u32 xpp_pad;
+ __u8 xpp_name[XFS_PPTR_MAXNAMELEN]; /* File name */
+};
+
+/* Iterate through an inodes parent pointers */
+struct xfs_pptr_info {
+ struct xfs_handle pi_handle;
+ struct xfs_attrlist_cursor pi_cursor;
+ __u32 pi_flags;
+ __u32 pi_reserved;
+ __u32 pi_ptrs_size;
+ __u32 pi_ptrs_used;
+ __u64 pi_reserved2[6];
+
+ /*
+ * An array of struct xfs_parent_ptr follows the header
+ * information. Use XFS_PPINFO_TO_PP() to access the
+ * parent pointer array entries.
+ */
+ struct xfs_parent_ptr pi_parents[];
+};
+
+static inline size_t
+xfs_pptr_info_sizeof(int nr_ptrs)
+{
+ return sizeof(struct xfs_pptr_info) +
+ (nr_ptrs * sizeof(struct xfs_parent_ptr));
+}
+
+static inline struct xfs_parent_ptr*
+xfs_ppinfo_to_pp(
+ struct xfs_pptr_info *info,
+ int idx)
+{
+
+ return &info->pi_parents[idx];
+}
+
/*
* ioctl limits
*/
@@ -797,6 +853,7 @@ struct xfs_scrub_metadata {
/* XFS_IOC_GETFSMAP ------ hoisted 59 */
#define XFS_IOC_SCRUB_METADATA _IOWR('X', 60, struct xfs_scrub_metadata)
#define XFS_IOC_AG_GEOMETRY _IOWR('X', 61, struct xfs_ag_geometry)
+#define XFS_IOC_GETPPOINTER _IOR ('X', 62, struct xfs_parent_ptr)

/*
* ioctl commands that replace IRIX syssgi()'s
diff --git a/fs/xfs/libxfs/xfs_parent.c b/fs/xfs/libxfs/xfs_parent.c
index 03f03f731d02..d9c922a78617 100644
--- a/fs/xfs/libxfs/xfs_parent.c
+++ b/fs/xfs/libxfs/xfs_parent.c
@@ -26,6 +26,16 @@
#include "xfs_xattr.h"
#include "xfs_parent.h"

+/* Initializes a xfs_parent_ptr from an xfs_parent_name_rec */
+void
+xfs_init_parent_ptr(struct xfs_parent_ptr *xpp,
+ struct xfs_parent_name_rec *rec)
+{
+ xpp->xpp_ino = be64_to_cpu(rec->p_ino);
+ xpp->xpp_gen = be32_to_cpu(rec->p_gen);
+ xpp->xpp_diroffset = be32_to_cpu(rec->p_diroffset);
+}
+
/*
* Parent pointer attribute handling.
*
diff --git a/fs/xfs/libxfs/xfs_parent.h b/fs/xfs/libxfs/xfs_parent.h
index 67948f4b3834..53161b79d1e2 100644
--- a/fs/xfs/libxfs/xfs_parent.h
+++ b/fs/xfs/libxfs/xfs_parent.h
@@ -23,6 +23,8 @@ void xfs_init_parent_name_rec(struct xfs_parent_name_rec *rec,
uint32_t p_diroffset);
void xfs_init_parent_name_irec(struct xfs_parent_name_irec *irec,
struct xfs_parent_name_rec *rec);
+void xfs_init_parent_ptr(struct xfs_parent_ptr *xpp,
+ struct xfs_parent_name_rec *rec);
int xfs_parent_init(xfs_mount_t *mp, xfs_inode_t *ip,
struct xfs_name *target_name,
struct xfs_parent_defer **parentp);
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 5b600d3f7981..8a9530588ef4 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -37,6 +37,7 @@
#include "xfs_health.h"
#include "xfs_reflink.h"
#include "xfs_ioctl.h"
+#include "xfs_parent_utils.h"
#include "xfs_xattr.h"

#include <linux/mount.h>
@@ -355,6 +356,8 @@ xfs_attr_filter(
return XFS_ATTR_ROOT;
if (ioc_flags & XFS_IOC_ATTR_SECURE)
return XFS_ATTR_SECURE;
+ if (ioc_flags & XFS_IOC_ATTR_PARENT)
+ return XFS_ATTR_PARENT;
return 0;
}

@@ -422,7 +425,8 @@ xfs_ioc_attr_list(
/*
* Reject flags, only allow namespaces.
*/
- if (flags & ~(XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE))
+ if (flags & ~(XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE |
+ XFS_IOC_ATTR_PARENT))
return -EINVAL;
if (flags == (XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE))
return -EINVAL;
@@ -1679,6 +1683,92 @@ xfs_ioc_scrub_metadata(
return 0;
}

+/*
+ * IOCTL routine to get the parent pointers of an inode and return it to user
+ * space. Caller must pass a buffer space containing a struct xfs_pptr_info,
+ * followed by a region large enough to contain an array of struct
+ * xfs_parent_ptr of a size specified in pi_ptrs_size. If the inode contains
+ * more parent pointers than can fit in the buffer space, caller may re-call
+ * the function using the returned pi_cursor to resume iteration. The
+ * number of xfs_parent_ptr returned will be stored in pi_ptrs_used.
+ *
+ * Returns 0 on success or non-zero on failure
+ */
+STATIC int
+xfs_ioc_get_parent_pointer(
+ struct file *filp,
+ void __user *arg)
+{
+ struct xfs_pptr_info *ppi = NULL;
+ int error = 0;
+ struct xfs_inode *ip = XFS_I(file_inode(filp));
+ struct xfs_mount *mp = ip->i_mount;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* Allocate an xfs_pptr_info to put the user data */
+ ppi = kmem_alloc(sizeof(struct xfs_pptr_info), 0);
+ if (!ppi)
+ return -ENOMEM;
+
+ /* Copy the data from the user */
+ error = copy_from_user(ppi, arg, sizeof(struct xfs_pptr_info));
+ if (error)
+ goto out;
+
+ /* Check size of buffer requested by user */
+ if (xfs_pptr_info_sizeof(ppi->pi_ptrs_size) > XFS_XATTR_LIST_MAX) {
+ error = -ENOMEM;
+ goto out;
+ }
+
+ if (ppi->pi_flags != 0 && ppi->pi_flags != XFS_PPTR_IFLAG_HANDLE) {
+ error = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * Now that we know how big the trailing buffer is, expand
+ * our kernel xfs_pptr_info to be the same size
+ */
+ ppi = krealloc(ppi, xfs_pptr_info_sizeof(ppi->pi_ptrs_size),
+ GFP_NOFS | __GFP_NOFAIL);
+ if (!ppi)
+ return -ENOMEM;
+
+ if (ppi->pi_flags == XFS_PPTR_IFLAG_HANDLE) {
+ error = xfs_iget(mp, NULL, ppi->pi_handle.ha_fid.fid_ino,
+ 0, 0, &ip);
+ if (error)
+ goto out;
+
+ if (VFS_I(ip)->i_generation != ppi->pi_handle.ha_fid.fid_gen) {
+ error = -EINVAL;
+ goto out;
+ }
+ }
+
+ if (ip->i_ino == mp->m_sb.sb_rootino)
+ ppi->pi_flags |= XFS_PPTR_OFLAG_ROOT;
+
+ /* Get the parent pointers */
+ error = xfs_attr_get_parent_pointer(ip, ppi);
+
+ if (error)
+ goto out;
+
+ /* Copy the parent pointers back to the user */
+ error = copy_to_user(arg, ppi,
+ xfs_pptr_info_sizeof(ppi->pi_ptrs_size));
+ if (error)
+ goto out;
+
+out:
+ kmem_free(ppi);
+ return error;
+}
+
int
xfs_ioc_swapext(
xfs_swapext_t *sxp)
@@ -1968,7 +2058,8 @@ xfs_file_ioctl(

case XFS_IOC_FSGETXATTRA:
return xfs_ioc_fsgetxattra(ip, arg);
-
+ case XFS_IOC_GETPPOINTER:
+ return xfs_ioc_get_parent_pointer(filp, arg);
case XFS_IOC_GETBMAP:
case XFS_IOC_GETBMAPA:
case XFS_IOC_GETBMAPX:
diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index 758702b9495f..765eb514a917 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -135,6 +135,10 @@ xfs_check_ondisk_structs(void)
XFS_CHECK_STRUCT_SIZE(struct xfs_attri_log_format, 40);
XFS_CHECK_STRUCT_SIZE(struct xfs_attrd_log_format, 16);

+ /* parent pointer ioctls */
+ XFS_CHECK_STRUCT_SIZE(struct xfs_parent_ptr, 280);
+ XFS_CHECK_STRUCT_SIZE(struct xfs_pptr_info, 104);
+
/*
* The v5 superblock format extended several v4 header structures with
* additional data. While new fields are only accessible on v5
diff --git a/fs/xfs/xfs_parent_utils.c b/fs/xfs/xfs_parent_utils.c
new file mode 100644
index 000000000000..3351ce173075
--- /dev/null
+++ b/fs/xfs/xfs_parent_utils.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2015 Red Hat, Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation
+ */
+#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"
+
+/*
+ * Get the parent pointers for a given inode
+ *
+ * Returns 0 on success and non zero on error
+ */
+int
+xfs_attr_get_parent_pointer(struct xfs_inode *ip,
+ struct xfs_pptr_info *ppi)
+
+{
+
+ struct xfs_attrlist *alist;
+ struct xfs_attrlist_ent *aent;
+ struct xfs_parent_ptr *xpp;
+ struct xfs_parent_name_rec *xpnr;
+ char *namebuf;
+ unsigned int namebuf_size;
+ int name_len;
+ int error = 0;
+ unsigned int ioc_flags = XFS_IOC_ATTR_PARENT;
+ unsigned int flags = XFS_ATTR_PARENT;
+ int i;
+ struct xfs_attr_list_context context;
+
+ /* Allocate a buffer to store the attribute names */
+ namebuf_size = sizeof(struct xfs_attrlist) +
+ (ppi->pi_ptrs_size) * sizeof(struct xfs_attrlist_ent);
+ namebuf = kvzalloc(namebuf_size, GFP_KERNEL);
+ if (!namebuf)
+ return -ENOMEM;
+
+ memset(&context, 0, sizeof(struct xfs_attr_list_context));
+ error = xfs_ioc_attr_list_context_init(ip, namebuf, namebuf_size,
+ ioc_flags, &context);
+
+ /* Copy the cursor provided by caller */
+ memcpy(&context.cursor, &ppi->pi_cursor,
+ sizeof(struct xfs_attrlist_cursor));
+
+ if (error)
+ goto out_kfree;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+
+ error = xfs_attr_list_ilocked(&context);
+ if (error)
+ goto out_kfree;
+
+ alist = (struct xfs_attrlist *)namebuf;
+ for (i = 0; i < alist->al_count; i++) {
+ struct xfs_da_args args = {
+ .geo = ip->i_mount->m_attr_geo,
+ .whichfork = XFS_ATTR_FORK,
+ .dp = ip,
+ .namelen = sizeof(struct xfs_parent_name_rec),
+ .attr_filter = flags,
+ .op_flags = XFS_DA_OP_OKNOENT,
+ };
+
+ xpp = xfs_ppinfo_to_pp(ppi, i);
+ memset(xpp, 0, sizeof(struct xfs_parent_ptr));
+ aent = (struct xfs_attrlist_ent *)
+ &namebuf[alist->al_offset[i]];
+ xpnr = (struct xfs_parent_name_rec *)(aent->a_name);
+
+ if (aent->a_valuelen > XFS_PPTR_MAXNAMELEN) {
+ error = -ERANGE;
+ goto out_kfree;
+ }
+ name_len = aent->a_valuelen;
+
+ args.name = (char *)xpnr;
+ args.hashval = xfs_da_hashname(args.name, args.namelen),
+ args.value = (unsigned char *)(xpp->xpp_name);
+ args.valuelen = name_len;
+
+ error = xfs_attr_get_ilocked(&args);
+ error = (error == -EEXIST ? 0 : error);
+ if (error)
+ goto out_kfree;
+
+ xpp->xpp_namelen = name_len;
+ xfs_init_parent_ptr(xpp, xpnr);
+ }
+ ppi->pi_ptrs_used = alist->al_count;
+ if (!alist->al_more)
+ ppi->pi_flags |= XFS_PPTR_OFLAG_DONE;
+
+ /* Update the caller with the current cursor position */
+ memcpy(&ppi->pi_cursor, &context.cursor,
+ sizeof(struct xfs_attrlist_cursor));
+
+out_kfree:
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ kmem_free(namebuf);
+
+ return error;
+}
+
diff --git a/fs/xfs/xfs_parent_utils.h b/fs/xfs/xfs_parent_utils.h
new file mode 100644
index 000000000000..0e952b2ebd4a
--- /dev/null
+++ b/fs/xfs/xfs_parent_utils.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2017 Oracle, Inc.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation Inc.
+ */
+#ifndef __XFS_PARENT_UTILS_H__
+#define __XFS_PARENT_UTILS_H__
+
+int xfs_attr_get_parent_pointer(struct xfs_inode *ip,
+ struct xfs_pptr_info *ppi);
+#endif /* __XFS_PARENT_UTILS_H__ */
--
2.25.1