fs/xfs/xfs_symlink_remote.c

   1 /*
   2  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   3  * Copyright (c) 2012-2013 Red Hat, Inc.
   4  * All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it would be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write the Free Software Foundation,
  17  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19 #include "xfs.h"
  20 #include "xfs_fs.h"
  21 #include "xfs_format.h"
  22 #include "xfs_log_format.h"
  23 #include "xfs_shared.h"
  24 #include "xfs_trans_resv.h"
  25 #include "xfs_ag.h"
  26 #include "xfs_sb.h"
  27 #include "xfs_mount.h"
  28 #include "xfs_bmap_btree.h"
  29 #include "xfs_inode.h"
  30 #include "xfs_error.h"
  31 #include "xfs_trace.h"
  32 #include "xfs_symlink.h"
  33 #include "xfs_cksum.h"
  34 #include "xfs_trans.h"
  35 #include "xfs_buf_item.h"
  36
  37
  38 /*
  39  * Each contiguous block has a header, so it is not just a simple pathlen
  40  * to FSB conversion.
  41  */
  42 int
  43 xfs_symlink_blocks(
  44         struct xfs_mount *mp,
  45         int             pathlen)
  46 {
  47         int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
  48
  49         return (pathlen + buflen - 1) / buflen;
  50 }
  51
  52 int
  53 xfs_symlink_hdr_set(
  54         struct xfs_mount        *mp,
  55         xfs_ino_t               ino,
  56         uint32_t                offset,
  57         uint32_t                size,
  58         struct xfs_buf          *bp)
  59 {
  60         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  61
  62         if (!xfs_sb_version_hascrc(&mp->m_sb))
  63                 return 0;
  64
  65         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  66         dsl->sl_offset = cpu_to_be32(offset);
  67         dsl->sl_bytes = cpu_to_be32(size);
  68         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
  69         dsl->sl_owner = cpu_to_be64(ino);
  70         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  71         bp->b_ops = &xfs_symlink_buf_ops;
  72
  73         return sizeof(struct xfs_dsymlink_hdr);
  74 }
  75
  76 /*
  77  * Checking of the symlink header is split into two parts. the verifier does
  78  * CRC, location and bounds checking, the unpacking function checks the path
  79  * parameters and owner.
  80  */
  81 bool
  82 xfs_symlink_hdr_ok(
  83         xfs_ino_t               ino,
  84         uint32_t                offset,
  85         uint32_t                size,
  86         struct xfs_buf          *bp)
  87 {
  88         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  89
  90         if (offset != be32_to_cpu(dsl->sl_offset))
  91                 return false;
  92         if (size != be32_to_cpu(dsl->sl_bytes))
  93                 return false;
  94         if (ino != be64_to_cpu(dsl->sl_owner))
  95                 return false;
  96
  97         /* ok */
  98         return true;
  99 }
 100
 101 static bool
 102 xfs_symlink_verify(
 103         struct xfs_buf          *bp)
 104 {
 105         struct xfs_mount        *mp = bp->b_target->bt_mount;
 106         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 107
 108         if (!xfs_sb_version_hascrc(&mp->m_sb))
 109                 return false;
 110         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 111                 return false;
 112         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
 113                 return false;
 114         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 115                 return false;
 116         if (be32_to_cpu(dsl->sl_offset) +
 117                                 be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
 118                 return false;
 119         if (dsl->sl_owner == 0)
 120                 return false;
 121
 122         return true;
 123 }
 124
 125 static void
 126 xfs_symlink_read_verify(
 127         struct xfs_buf  *bp)
 128 {
 129         struct xfs_mount *mp = bp->b_target->bt_mount;
 130
 131         /* no verification of non-crc buffers */
 132         if (!xfs_sb_version_hascrc(&mp->m_sb))
 133                 return;
 134
 135         if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
 136                 xfs_buf_ioerror(bp, EFSBADCRC);
 137         else if (!xfs_symlink_verify(bp))
 138                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 139
 140         if (bp->b_error)
 141                 xfs_verifier_error(bp);
 142 }
 143
 144 static void
 145 xfs_symlink_write_verify(
 146         struct xfs_buf  *bp)
 147 {
 148         struct xfs_mount *mp = bp->b_target->bt_mount;
 149         struct xfs_buf_log_item *bip = bp->b_fspriv;
 150
 151         /* no verification of non-crc buffers */
 152         if (!xfs_sb_version_hascrc(&mp->m_sb))
 153                 return;
 154
 155         if (!xfs_symlink_verify(bp)) {
 156                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 157                 xfs_verifier_error(bp);
 158                 return;
 159         }
 160
 161         if (bip) {
 162                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 163                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 164         }
 165         xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
 166 }
 167
 168 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 169         .verify_read = xfs_symlink_read_verify,
 170         .verify_write = xfs_symlink_write_verify,
 171 };
 172
 173 void
 174 xfs_symlink_local_to_remote(
 175         struct xfs_trans        *tp,
 176         struct xfs_buf          *bp,
 177         struct xfs_inode        *ip,
 178         struct xfs_ifork        *ifp)
 179 {
 180         struct xfs_mount        *mp = ip->i_mount;
 181         char                    *buf;
 182
 183         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 184                 bp->b_ops = NULL;
 185                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 186                 return;
 187         }
 188
 189         /*
 190          * As this symlink fits in an inode literal area, it must also fit in
 191          * the smallest buffer the filesystem supports.
 192          */
 193         ASSERT(BBTOB(bp->b_length) >=
 194                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 195
 196         bp->b_ops = &xfs_symlink_buf_ops;
 197
 198         buf = bp->b_addr;
 199         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 200         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 201 }