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| author | Steven J. Magnani <steve.magnani@digidescorp.com> | 2019-07-11 08:38:52 -0500 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2019-07-31 12:04:42 +0200 |
| commit | 6fbacb8539a6659d446a9efabb538cfc007c1427 (patch) | |
| tree | 5f9649197f4f6df4c766a0a629e11dafc16f5843 /fs/udf | |
| parent | ba54aef0313322d9eea0fca648170d5a3c906de4 (diff) | |
| download | lwn-6fbacb8539a6659d446a9efabb538cfc007c1427.tar.gz lwn-6fbacb8539a6659d446a9efabb538cfc007c1427.zip | |
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.c | 16 |
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); } |