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authorSteven J. Magnani <steve.magnani@digidescorp.com>2019-07-11 08:38:52 -0500
committerJan Kara <jack@suse.cz>2019-07-31 12:04:42 +0200
commit6fbacb8539a6659d446a9efabb538cfc007c1427 (patch)
tree5f9649197f4f6df4c766a0a629e11dafc16f5843 /fs/udf
parentba54aef0313322d9eea0fca648170d5a3c906de4 (diff)
udf: support 2048-byte spacing of VRS descriptors on 4K media
Some UDF creators (specifically Microsoft, but perhaps others) mishandle the ECMA-167 corner case that requires descriptors within a Volume Recognition Sequence to be placed at 4096-byte intervals on media where the block size is 4K. Instead, the descriptors are placed at the 2048- byte interval mandated for media with smaller blocks. This nonconformity currently prevents Linux from recognizing the filesystem as UDF. Modify the driver to tolerate a misformatted VRS on 4K media. [JK: Simplified descriptor checking] Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Tested-by: Steven J. Magnani <steve@digidescorp.com> Link: https://lore.kernel.org/r/20190711133852.16887-2-steve@digidescorp.com Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/udf')
-rw-r--r--fs/udf/super.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/fs/udf/super.c b/fs/udf/super.c
index 14a91955507b..f34e06b4d8fa 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -739,6 +739,22 @@ static int udf_check_vsd(struct super_block *sb)
vsd = (struct volStructDesc *)(bh->b_data +
(sector & (sb->s_blocksize - 1)));
nsr = identify_vsd(vsd);
+ /* Found NSR or end? */
+ if (nsr) {
+ brelse(bh);
+ break;
+ }
+ /*
+ * Special handling for improperly formatted VRS (e.g., Win10)
+ * where components are separated by 2048 bytes even though
+ * sectors are 4K
+ */
+ if (sb->s_blocksize == 4096) {
+ nsr = identify_vsd(vsd + 1);
+ /* Ignore unknown IDs... */
+ if (nsr < 0)
+ nsr = 0;
+ }
brelse(bh);
}