LXR linux/fs/xfs/xfs

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (c) 2004-2005 Silicon Graphics, Inc.
   4 * All Rights Reserved.
   5 */
   6#include "xfs.h"
   7#include "xfs_shared.h"
   8#include "xfs_format.h"
   9#include "xfs_log_format.h"
  10#include "xfs_trans_resv.h"
  11#include "xfs_mount.h"
  12#include "xfs_dir2.h"
  13#include "xfs_export.h"
  14#include "xfs_inode.h"
  15#include "xfs_trans.h"
  16#include "xfs_inode_item.h"
  17#include "xfs_icache.h"
  18#include "xfs_log.h"
  19#include "xfs_pnfs.h"
  20
  21/*
  22 * Note that we only accept fileids which are long enough rather than allow
  23 * the parent generation number to default to zero.  XFS considers zero a
  24 * valid generation number not an invalid/wildcard value.
  25 */
  26static int xfs_fileid_length(int fileid_type)
  27{
  28        switch (fileid_type) {
  29        case FILEID_INO32_GEN:
  30                return 2;
  31        case FILEID_INO32_GEN_PARENT:
  32                return 4;
  33        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  34                return 3;
  35        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  36                return 6;
  37        }
  38        return FILEID_INVALID;
  39}
  40
  41STATIC int
  42xfs_fs_encode_fh(
  43        struct inode    *inode,
  44        __u32           *fh,
  45        int             *max_len,
  46        struct inode    *parent)
  47{
  48        struct fid              *fid = (struct fid *)fh;
  49        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  50        int                     fileid_type;
  51        int                     len;
  52
  53        /* Directories don't need their parent encoded, they have ".." */
  54        if (!parent)
  55                fileid_type = FILEID_INO32_GEN;
  56        else
  57                fileid_type = FILEID_INO32_GEN_PARENT;
  58
  59        /*
  60         * If the the filesystem may contain 64bit inode numbers, we need
  61         * to use larger file handles that can represent them.
  62         *
  63         * While we only allocate inodes that do not fit into 32 bits any
  64         * large enough filesystem may contain them, thus the slightly
  65         * confusing looking conditional below.
  66         */
  67        if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  68            (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  69                fileid_type |= XFS_FILEID_TYPE_64FLAG;
  70
  71        /*
  72         * Only encode if there is enough space given.  In practice
  73         * this means we can't export a filesystem with 64bit inodes
  74         * over NFSv2 with the subtree_check export option; the other
  75         * seven combinations work.  The real answer is "don't use v2".
  76         */
  77        len = xfs_fileid_length(fileid_type);
  78        if (*max_len < len) {
  79                *max_len = len;
  80                return FILEID_INVALID;
  81        }
  82        *max_len = len;
  83
  84        switch (fileid_type) {
  85        case FILEID_INO32_GEN_PARENT:
  86                fid->i32.parent_ino = XFS_I(parent)->i_ino;
  87                fid->i32.parent_gen = parent->i_generation;
  88                /*FALLTHRU*/
  89        case FILEID_INO32_GEN:
  90                fid->i32.ino = XFS_I(inode)->i_ino;
  91                fid->i32.gen = inode->i_generation;
  92                break;
  93        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  94                fid64->parent_ino = XFS_I(parent)->i_ino;
  95                fid64->parent_gen = parent->i_generation;
  96                /*FALLTHRU*/
  97        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  98                fid64->ino = XFS_I(inode)->i_ino;
  99                fid64->gen = inode->i_generation;
 100                break;
 101        }
 102
 103        return fileid_type;
 104}
 105
 106STATIC struct inode *
 107xfs_nfs_get_inode(
 108        struct super_block      *sb,
 109        u64                     ino,
 110        u32                     generation)
 111{
 112        xfs_mount_t             *mp = XFS_M(sb);
 113        xfs_inode_t             *ip;
 114        int                     error;
 115
 116        /*
 117         * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 118         */
 119        if (ino == 0)
 120                return ERR_PTR(-ESTALE);
 121
 122        /*
 123         * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 124         * fine and not an indication of a corrupted filesystem as clients can
 125         * send invalid file handles and we have to handle it gracefully..
 126         */
 127        error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 128        if (error) {
 129
 130                /*
 131                 * EINVAL means the inode cluster doesn't exist anymore.
 132                 * EFSCORRUPTED means the metadata pointing to the inode cluster
 133                 * or the inode cluster itself is corrupt.  This implies the
 134                 * filehandle is stale, so we should translate it here.
 135                 * We don't use ESTALE directly down the chain to not
 136                 * confuse applications using bulkstat that expect EINVAL.
 137                 */
 138                switch (error) {
 139                case -EINVAL:
 140                case -ENOENT:
 141                case -EFSCORRUPTED:
 142                        error = -ESTALE;
 143                        break;
 144                default:
 145                        break;
 146                }
 147                return ERR_PTR(error);
 148        }
 149
 150        if (VFS_I(ip)->i_generation != generation) {
 151                xfs_irele(ip);
 152                return ERR_PTR(-ESTALE);
 153        }
 154
 155        return VFS_I(ip);
 156}
 157
 158STATIC struct dentry *
 159xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 160                 int fh_len, int fileid_type)
 161{
 162        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 163        struct inode            *inode = NULL;
 164
 165        if (fh_len < xfs_fileid_length(fileid_type))
 166                return NULL;
 167
 168        switch (fileid_type) {
 169        case FILEID_INO32_GEN_PARENT:
 170        case FILEID_INO32_GEN:
 171                inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 172                break;
 173        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 174        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 175                inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 176                break;
 177        }
 178
 179        return d_obtain_alias(inode);
 180}
 181
 182STATIC struct dentry *
 183xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 184                 int fh_len, int fileid_type)
 185{
 186        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 187        struct inode            *inode = NULL;
 188
 189        if (fh_len < xfs_fileid_length(fileid_type))
 190                return NULL;
 191
 192        switch (fileid_type) {
 193        case FILEID_INO32_GEN_PARENT:
 194                inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 195                                              fid->i32.parent_gen);
 196                break;
 197        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 198                inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 199                                              fid64->parent_gen);
 200                break;
 201        }
 202
 203        return d_obtain_alias(inode);
 204}
 205
 206STATIC struct dentry *
 207xfs_fs_get_parent(
 208        struct dentry           *child)
 209{
 210        int                     error;
 211        struct xfs_inode        *cip;
 212
 213        error = xfs_lookup(XFS_I(d_inode(child)), &xfs_name_dotdot, &cip, NULL);
 214        if (unlikely(error))
 215                return ERR_PTR(error);
 216
 217        return d_obtain_alias(VFS_I(cip));
 218}
 219
 220STATIC int
 221xfs_fs_nfs_commit_metadata(
 222        struct inode            *inode)
 223{
 224        struct xfs_inode        *ip = XFS_I(inode);
 225        struct xfs_mount        *mp = ip->i_mount;
 226        xfs_lsn_t               lsn = 0;
 227
 228        xfs_ilock(ip, XFS_ILOCK_SHARED);
 229        if (xfs_ipincount(ip))
 230                lsn = ip->i_itemp->ili_last_lsn;
 231        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 232
 233        if (!lsn)
 234                return 0;
 235        return xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 236}
 237
 238const struct export_operations xfs_export_operations = {
 239        .encode_fh              = xfs_fs_encode_fh,
 240        .fh_to_dentry           = xfs_fs_fh_to_dentry,
 241        .fh_to_parent           = xfs_fs_fh_to_parent,
 242        .get_parent             = xfs_fs_get_parent,
 243        .commit_metadata        = xfs_fs_nfs_commit_metadata,
 244#ifdef CONFIG_EXPORTFS_BLOCK_OPS
 245        .get_uuid               = xfs_fs_get_uuid,
 246        .map_blocks             = xfs_fs_map_blocks,
 247        .commit_blocks          = xfs_fs_commit_blocks,
 248#endif
 249};
 250