mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-03 07:36:10 -04:00
6b9857b208
Some of the folio_end_*() helpers are prone to overflow of signed 64-bit types because the mapping is only limited by the max value of loff_t and the associated helpers return the start offset of the next folio. Therefore, a folio_end_pos() of the max allowable folio in a mapping returns a value that overflows loff_t. This makes it hard to rely on such values when doing folio processing across a range of a file, as bcachefs attempts to do with the recent folio changes. For example, generic/564 causes problems in the buffered write path when testing writes at max boundary conditions. The current understanding is that the pagecache historically limited the mapping to one less page to avoid this problem and this was dropped with some of the folio conversions, but may be reinstated to properly address the problem. In the meantime, update the internal folio_end_*() helpers in bcachefs to return a u64, and all of the associated code to use or cast to u64 to avoid overflow problems. This allows generic/564 to pass and can be reverted back to using loff_t if at any point the pagecache subsystem can guarantee these boundary conditions will not overflow. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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.