On Sat, Jun 11, 2022 at 02:42:00AM -0700, Allison Henderson wrote:
> This patch adds a new file ioctl to retrieve the parent pointer of a
> given inode
>
> Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
> ---
> fs/xfs/Makefile | 1 +
> fs/xfs/libxfs/xfs_fs.h | 46 +++++++++++++
> fs/xfs/libxfs/xfs_parent.c | 10 +++
> fs/xfs/libxfs/xfs_parent.h | 2 +
> fs/xfs/xfs_ioctl.c | 90 ++++++++++++++++++++++++-
> fs/xfs/xfs_ondisk.h | 4 ++
> fs/xfs/xfs_parent_utils.c | 133 +++++++++++++++++++++++++++++++++++++
> fs/xfs/xfs_parent_utils.h | 22 ++++++
> 8 files changed, 306 insertions(+), 2 deletions(-)
>
> diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
> index fc717dc3470c..da86f6231f2e 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..e6c8873cd234 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 +753,50 @@ 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[];
Unless you want to conserve space in the userspace buffer by making the
size of xfs_parent_ptr itself variable? Userspace would have to walk
the entire buffer by hand like it does for listxattr, but it saves a
fair amount of space.
> +};
> +
> +#define XFS_PPTR_INFO_SIZEOF(nr_ptrs) sizeof (struct xfs_pptr_info) + \
> + nr_ptrs * sizeof(struct xfs_parent_ptr)
> +
> +#define XFS_PPINFO_TO_PP(info, idx) \
> + (&(((struct xfs_parent_ptr *)((char *)(info) + sizeof(*(info))))[(idx)]))
Turn these into static inline functions so that client programs get some
proper typechecking by the C compiler.
> +
> /*
> * ioctl limits
> */
> @@ -797,6 +842,7 @@ 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 cb546652bde9..a5b99f30bc63 100644
> --- a/fs/xfs/libxfs/xfs_parent.c
> +++ b/fs/xfs/libxfs/xfs_parent.c
> @@ -33,6 +33,16 @@
> #include "xfs_attr_sf.h"
> #include "xfs_bmap.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)
Indenting...
> +{
> + 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 10dc576ce693..fa50ada0d6a9 100644
> --- a/fs/xfs/libxfs/xfs_parent.h
> +++ b/fs/xfs/libxfs/xfs_parent.h
> @@ -28,4 +28,6 @@ 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);
> #endif /* __XFS_PARENT_H__ */
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index e1612e99e0c5..4cd1de3e9d0b 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;
> @@ -1672,6 +1676,87 @@ 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;
> + }
> +
> + /*
> + * 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 != 0 && ppi->pi_flags != XFS_PPTR_IFLAG_HANDLE) {
Flags validation should come before the big memory allocation.
> + error = -EINVAL;
> + goto out;
> + }
> +
> + 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;
This ought to be checking the generation number in the file handle.
> + }
> +
> + 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)
> @@ -1961,7 +2046,8 @@ 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..9880718395c6
> --- /dev/null
> +++ b/fs/xfs/xfs_parent_utils.c
> @@ -0,0 +1,133 @@
> +/*
> + * 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)
> +
Indenting. Also, should this go in xfs_parent.c ?
> +{
> +
> + 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;
> + struct xfs_da_args args;
> +
> + /* 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++) {
> + 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;
> +
> + memset(&args, 0, sizeof(args));
> + args.geo = ip->i_mount->m_attr_geo;
> + args.whichfork = XFS_ATTR_FORK;
> + args.dp = ip;
> + args.name = (char *)xpnr;
> + args.namelen = sizeof(struct xfs_parent_name_rec);
> + args.attr_filter = flags;
> + args.hashval = xfs_da_hashname(args.name, args.namelen);
> + args.value = (unsigned char *)(xpp->xpp_name);
> + args.valuelen = name_len;
> + args.op_flags = XFS_DA_OP_OKNOENT;
You might want to convert this to a C99 named initialization inside the
loop body.
Otherwise looks ok.
--D
> +
> + 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
>
