// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2022-2024 Oracle.
 * All rights reserved.
 */
#include "xfs_platform.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_da_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_btree.h"
#include "xfs_attr.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "xfs_attr_sf.h"
#include "xfs_bmap.h"
#include "xfs_defer.h"
#include "xfs_log.h"
#include "xfs_xattr.h"
#include "xfs_parent.h"
#include "xfs_trans_space.h"
#include "xfs_attr_item.h"
#include "xfs_health.h"
#include "xfs_attr_leaf.h"

struct kmem_cache               *xfs_parent_args_cache;

/*
 * Parent pointer attribute handling.
 *
 * Because the attribute name is a filename component, it will never be longer
 * than 255 bytes and must not contain nulls or slashes.  These are roughly the
 * same constraints that apply to attribute names.
 *
 * The attribute value must always be a struct xfs_parent_rec.  This means the
 * attribute will never be in remote format because 12 bytes is nowhere near
 * xfs_attr_leaf_entsize_local_max() (~75% of block size).
 *
 * Creating a new parent attribute will always create a new attribute - there
 * should never, ever be an existing attribute in the tree for a new inode.
 * ENOSPC behavior is problematic - creating the inode without the parent
 * pointer is effectively a corruption, so we allow parent attribute creation
 * to dip into the reserve block pool to avoid unexpected ENOSPC errors from
 * occurring.
 */

/* Return true if parent pointer attr name is valid. */
bool
xfs_parent_namecheck(
        unsigned int                    attr_flags,
        const void                      *name,
        size_t                          length)
{
        /*
         * Parent pointers always use logged operations, so there should never
         * be incomplete xattrs.
         */
        if (attr_flags & XFS_ATTR_INCOMPLETE)
                return false;

        return xfs_dir2_namecheck(name, length);
}

/* Return true if parent pointer attr value is valid. */
bool
xfs_parent_valuecheck(
        struct xfs_mount                *mp,
        const void                      *value,
        size_t                          valuelen)
{
        const struct xfs_parent_rec     *rec = value;

        if (!xfs_has_parent(mp))
                return false;

        /* The xattr value must be a parent record. */
        if (valuelen != sizeof(struct xfs_parent_rec))
                return false;

        /* The parent record must be local. */
        if (value == NULL)
                return false;

        /* The parent inumber must be valid. */
        if (!xfs_verify_dir_ino(mp, be64_to_cpu(rec->p_ino)))
                return false;

        return true;
}

/* Compute the attribute name hash for a parent pointer. */
xfs_dahash_t
xfs_parent_hashval(
        struct xfs_mount                *mp,
        const uint8_t                   *name,
        int                             namelen,
        xfs_ino_t                       parent_ino)
{
        struct xfs_name                 xname = {
                .name                   = name,
                .len                    = namelen,
        };

        /*
         * Use the same dirent name hash as would be used on the directory, but
         * mix in the parent inode number to avoid collisions on hardlinked
         * files with identical names but different parents.
         */
        return xfs_dir2_hashname(mp, &xname) ^
                upper_32_bits(parent_ino) ^ lower_32_bits(parent_ino);
}

/* Compute the attribute name hash from the xattr components. */
xfs_dahash_t
xfs_parent_hashattr(
        struct xfs_mount                *mp,
        const uint8_t                   *name,
        int                             namelen,
        const void                      *value,
        int                             valuelen)
{
        const struct xfs_parent_rec     *rec = value;

        /* Requires a local attr value in xfs_parent_rec format */
        if (valuelen != sizeof(struct xfs_parent_rec)) {
                ASSERT(valuelen == sizeof(struct xfs_parent_rec));
                return 0;
        }

        if (!value) {
                ASSERT(value != NULL);
                return 0;
        }

        return xfs_parent_hashval(mp, name, namelen, be64_to_cpu(rec->p_ino));
}

/*
 * Initialize the parent pointer arguments structure.  Caller must have zeroed
 * the contents of @args.  @tp is only required for updates.
 */
static void
xfs_parent_da_args_init(
        struct xfs_da_args      *args,
        struct xfs_trans        *tp,
        struct xfs_parent_rec   *rec,
        struct xfs_inode        *child,
        xfs_ino_t               owner,
        const struct xfs_name   *parent_name)
{
        args->geo = child->i_mount->m_attr_geo;
        args->whichfork = XFS_ATTR_FORK;
        args->attr_filter = XFS_ATTR_PARENT;
        args->op_flags = XFS_DA_OP_LOGGED | XFS_DA_OP_OKNOENT;
        args->trans = tp;
        args->dp = child;
        args->owner = owner;
        args->name = parent_name->name;
        args->namelen = parent_name->len;
        args->value = rec;
        args->valuelen = sizeof(struct xfs_parent_rec);
        xfs_attr_sethash(args);
}

/* Make sure the incore state is ready for a parent pointer query/update. */
static inline int
xfs_parent_iread_extents(
        struct xfs_trans        *tp,
        struct xfs_inode        *child)
{
        /* Parent pointers require that the attr fork must exist. */
        if (XFS_IS_CORRUPT(child->i_mount, !xfs_inode_has_attr_fork(child))) {
                xfs_inode_mark_sick(child, XFS_SICK_INO_PARENT);
                return -EFSCORRUPTED;
        }

        return xfs_iread_extents(tp, child, XFS_ATTR_FORK);
}

/* Add a parent pointer to reflect a dirent addition. */
int
xfs_parent_addname(
        struct xfs_trans        *tp,
        struct xfs_parent_args  *ppargs,
        struct xfs_inode        *dp,
        const struct xfs_name   *parent_name,
        struct xfs_inode        *child)
{
        int                     error;

        error = xfs_parent_iread_extents(tp, child);
        if (error)
                return error;

        xfs_inode_to_parent_rec(&ppargs->rec, dp);
        xfs_parent_da_args_init(&ppargs->args, tp, &ppargs->rec, child,
                        child->i_ino, parent_name);

        return xfs_attr_setname(&ppargs->args, 0);
}

/* Remove a parent pointer to reflect a dirent removal. */
int
xfs_parent_removename(
        struct xfs_trans        *tp,
        struct xfs_parent_args  *ppargs,
        struct xfs_inode        *dp,
        const struct xfs_name   *parent_name,
        struct xfs_inode        *child)
{
        int                     error;

        error = xfs_parent_iread_extents(tp, child);
        if (error)
                return error;

        xfs_inode_to_parent_rec(&ppargs->rec, dp);
        xfs_parent_da_args_init(&ppargs->args, tp, &ppargs->rec, child,
                        child->i_ino, parent_name);

        return xfs_attr_removename(&ppargs->args);
}

/* Replace one parent pointer with another to reflect a rename. */
int
xfs_parent_replacename(
        struct xfs_trans        *tp,
        struct xfs_parent_args  *ppargs,
        struct xfs_inode        *old_dp,
        const struct xfs_name   *old_name,
        struct xfs_inode        *new_dp,
        const struct xfs_name   *new_name,
        struct xfs_inode        *child)
{
        int                     error;

        error = xfs_parent_iread_extents(tp, child);
        if (error)
                return error;

        xfs_inode_to_parent_rec(&ppargs->rec, old_dp);
        xfs_parent_da_args_init(&ppargs->args, tp, &ppargs->rec, child,
                        child->i_ino, old_name);

        xfs_inode_to_parent_rec(&ppargs->new_rec, new_dp);

        ppargs->args.new_name = new_name->name;
        ppargs->args.new_namelen = new_name->len;
        ppargs->args.new_value = &ppargs->new_rec;
        ppargs->args.new_valuelen = sizeof(struct xfs_parent_rec);

        return xfs_attr_replacename(&ppargs->args, 0);
}

/*
 * Extract parent pointer information from any parent pointer xattr into
 * @parent_ino/gen.  The last two parameters can be NULL pointers.
 *
 * Returns 0 if this is not a parent pointer xattr at all; or -EFSCORRUPTED for
 * garbage.
 */
int
xfs_parent_from_attr(
        struct xfs_mount        *mp,
        unsigned int            attr_flags,
        const unsigned char     *name,
        unsigned int            namelen,
        const void              *value,
        unsigned int            valuelen,
        xfs_ino_t               *parent_ino,
        uint32_t                *parent_gen)
{
        const struct xfs_parent_rec     *rec = value;

        ASSERT(attr_flags & XFS_ATTR_PARENT);

        if (!xfs_parent_namecheck(attr_flags, name, namelen))
                return -EFSCORRUPTED;
        if (!xfs_parent_valuecheck(mp, value, valuelen))
                return -EFSCORRUPTED;

        if (parent_ino)
                *parent_ino = be64_to_cpu(rec->p_ino);
        if (parent_gen)
                *parent_gen = be32_to_cpu(rec->p_gen);
        return 0;
}

/*
 * Look up a parent pointer record (@parent_name -> @pptr) of @ip.
 *
 * Caller must hold at least ILOCK_SHARED.  The scratchpad need not be
 * initialized.
 *
 * Returns 0 if the pointer is found, -ENOATTR if there is no match, or a
 * negative errno.
 */
int
xfs_parent_lookup(
        struct xfs_trans                *tp,
        struct xfs_inode                *ip,
        const struct xfs_name           *parent_name,
        struct xfs_parent_rec           *pptr,
        struct xfs_da_args              *scratch)
{
        memset(scratch, 0, sizeof(struct xfs_da_args));
        xfs_parent_da_args_init(scratch, tp, pptr, ip, ip->i_ino, parent_name);
        return xfs_attr_get_ilocked(scratch);
}

/* Sanity-check a parent pointer before we try to perform repairs. */
static inline bool
xfs_parent_sanity_check(
        struct xfs_mount                *mp,
        const struct xfs_name           *parent_name,
        const struct xfs_parent_rec     *pptr)
{
        if (!xfs_parent_namecheck(XFS_ATTR_PARENT, parent_name->name,
                                parent_name->len))
                return false;

        if (!xfs_parent_valuecheck(mp, pptr, sizeof(*pptr)))
                return false;

        return true;
}


/*
 * Attach the parent pointer (@parent_name -> @pptr) to @ip immediately.
 * Caller must not have a transaction or hold the ILOCK.  This is for
 * specialized repair functions only.  The scratchpad need not be initialized.
 */
int
xfs_parent_set(
        struct xfs_inode        *ip,
        xfs_ino_t               owner,
        const struct xfs_name   *parent_name,
        struct xfs_parent_rec   *pptr,
        struct xfs_da_args      *scratch)
{
        if (!xfs_parent_sanity_check(ip->i_mount, parent_name, pptr)) {
                ASSERT(0);
                return -EFSCORRUPTED;
        }

        memset(scratch, 0, sizeof(struct xfs_da_args));
        xfs_parent_da_args_init(scratch, NULL, pptr, ip, owner, parent_name);
        return xfs_attr_set(scratch, XFS_ATTRUPDATE_CREATE, false);
}

/*
 * Remove the parent pointer (@parent_name -> @pptr) from @ip immediately.
 * Caller must not have a transaction or hold the ILOCK.  This is for
 * specialized repair functions only.  The scratchpad need not be initialized.
 */
int
xfs_parent_unset(
        struct xfs_inode                *ip,
        xfs_ino_t                       owner,
        const struct xfs_name           *parent_name,
        struct xfs_parent_rec           *pptr,
        struct xfs_da_args              *scratch)
{
        if (!xfs_parent_sanity_check(ip->i_mount, parent_name, pptr)) {
                ASSERT(0);
                return -EFSCORRUPTED;
        }

        memset(scratch, 0, sizeof(struct xfs_da_args));
        xfs_parent_da_args_init(scratch, NULL, pptr, ip, owner, parent_name);
        return xfs_attr_set(scratch, XFS_ATTRUPDATE_REMOVE, false);
}