udf: Simplify handling of Volume Descriptor Pointers

According to ECMA-167 3/8.4.2 Volume Descriptor Pointer is terminating
current extent of Volume Descriptor Sequence. Also according to ECMA-167
3/8.4.3 Volume Descriptor Sequence Number is not significant for Volume
Descriptor Pointers. Simplify the handling of Volume Descriptor Pointers
to take this into account.

Acked-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 5c5d5fd513cce6081eca6ffd2f81b16ae3e25b21..f80b97173acda29a1c7a7b1a23c03425fab72bf4 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1615,7 +1615,6 @@ static noinline int udf_process_sequence(
        bool done = false;
        uint32_t vdsn;
        uint16_t ident;
-       long next_s = 0, next_e = 0;
        int ret;
        unsigned int indirections = 0;
 
@@ -1647,19 +1646,22 @@ static noinline int udf_process_sequence(
                        }
                        break;
                case TAG_IDENT_VDP: /* ISO 13346 3/10.3 */
-                       curr = &vds[VDS_POS_VOL_DESC_PTR];
-                       if (vdsn >= curr->volDescSeqNum) {
-                               curr->volDescSeqNum = vdsn;
-                               curr->block = block;
-
-                               vdp = (struct volDescPtr *)bh->b_data;
-                               next_s = le32_to_cpu(
-                                       vdp->nextVolDescSeqExt.extLocation);
-                               next_e = le32_to_cpu(
-                                       vdp->nextVolDescSeqExt.extLength);
-                               next_e = next_e >> sb->s_blocksize_bits;
-                               next_e += next_s - 1;
+                       if (++indirections > UDF_MAX_TD_NESTING) {
+                               udf_err(sb, "too many Volume Descriptor "
+                                       "Pointers (max %u supported)\n",
+                                       UDF_MAX_TD_NESTING);
+                               brelse(bh);
+                               return -EIO;
                        }
+
+                       vdp = (struct volDescPtr *)bh->b_data;
+                       block = le32_to_cpu(vdp->nextVolDescSeqExt.extLocation);
+                       lastblock = le32_to_cpu(
+                               vdp->nextVolDescSeqExt.extLength) >>
+                               sb->s_blocksize_bits;
+                       lastblock += block - 1;
+                       /* For loop is going to increment 'block' again */
+                       block--;
                        break;
                case TAG_IDENT_IUVD: /* ISO 13346 3/10.4 */
                        curr = &vds[VDS_POS_IMP_USE_VOL_DESC];
@@ -1688,19 +1690,8 @@ static noinline int udf_process_sequence(
                        }
                        break;
                case TAG_IDENT_TD: /* ISO 13346 3/10.9 */
-                       if (++indirections > UDF_MAX_TD_NESTING) {
-                               udf_err(sb, "too many TDs (max %u supported)\n", UDF_MAX_TD_NESTING);
-                               brelse(bh);
-                               return -EIO;
-                       }
-
                        vds[VDS_POS_TERMINATING_DESC].block = block;
-                       if (next_e) {
-                               block = next_s;
-                               lastblock = next_e;
-                               next_s = next_e = 0;
-                       } else
-                               done = true;
+                       done = true;
                        break;
                }
                brelse(bh);