On Wed, 2022-06-29 at 11:52 -0700, Darrick J. Wong wrote:
> 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.
Oh i see, I can take a look at it. Honestly I think the only thing in
user space that's interested in parent pointers might be the test case,
so I'm not too worried about it atm. But let me see if I can cut down
the buffer usage a bit.
>
> > +};
> > +
> > +#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.
>
Sure, will do
> > +
> > /*
> > * 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...
>
Will fix
> > +{
> > + 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.
>
Alrighty, will scoot up
> > + 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.
Oh I see, sure I will add that in
>
> > + }
> > +
> > + 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 ?
>
Will fix indenting. I think the reason I put it here was to avoid
unnecessary porting to libxfs. Since parent.c is in libxfs and utils
is not.
> > +{
> > +
> > + 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.
Ok, will do.
>
> Otherwise looks ok.
>
Great! Thanks!
Allison
> --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
> >
