mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-03 18:12:25 -04:00
c3a22c2e4b
The attribute fork scrubber can optionally scan the reverse mapping records of the filesystem to determine if the fork is missing mappings that it should have. However, this is a very expensive operation, so we only want to do this if we suspect that the fork is missing records. For attribute forks the criteria for suspicion is that the attr fork is in EXTENTS format and has zero extents. However, there are several ways that a file can end up in this state through regular filesystem usage. For example, an LSM can set a s_security hook but then decide not to set an ACL; or an attr set can create the attr fork but then the actual set operation fails with ENOSPC; or we can delete all the attrs on a file whose data fork is in btree format, in which case we do not delete the attr fork. We don't want to run the expensive check for any case that can be arrived at through regular operations. However. When online inode repair decides to zap an attribute fork, it cannot determine if it is zapping ACL information. As a precaution it removes all the discretionary access control permissions and sets the user and group ids to zero. Check these three additional conditions to decide if we want to scan the rmap records. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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.