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15fb05fd28
UDF 2.60 standard states in section 2.2.14.2:
A partition with Access Type 3 (rewritable) shall define a Freed
Space Bitmap or a Freed Space Table, see 2.3.3. All other partitions
shall not define a Freed Space Bitmap or a Freed Space Table.
Rewritable partitions are used on media that require some form of
preprocessing before re-writing data (for example legacy MO). Such
partitions shall use Access Type 3.
Overwritable partitions are used on media that do not require
preprocessing before overwriting data (for example: CD-RW, DVD-RW,
DVD+RW, DVD-RAM, BD-RE, HD DVD-Rewritable). Such partitions shall
use Access Type 4.
however older versions of the standard didn't have this wording and
there are tools out there that create UDF filesystems with rewritable
partitions but that don't contain a Freed Space Bitmap or a Freed Space
Table on media that does not require pre-processing before overwriting a
block. So instead of forcing media with rewritable partition read-only,
base this decision on presence of a Freed Space Bitmap or a Freed Space
Table.
Reported-by: Pali Rohár <pali.rohar@gmail.com>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Fixes: b085fbe2ef ("udf: Fix crash during mount")
Link: https://lore.kernel.org/linux-fsdevel/20200112144735.hj2emsoy4uwsouxz@pali
Signed-off-by: Jan Kara <jack@suse.cz>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.