2e504418e4
At try_release_extent_mapping(), called during the release folio callback (btrfs_release_folio() callchain), we don't release any extent maps in the range if the GFP flags don't allow blocking. This behaviour is exaggerated because: 1) Both searching for extent maps and removing them are not blocking operations. The only thing that it is the cond_resched() call at the end of the loop that searches for and removes extent maps; 2) We currently only operate on a single page, so for the case where block size matches the page size, we can only have one extent map, and for the case where the block size is smaller than the page size, we can have at most 16 extent maps. So it's very unlikely the cond_resched() call will ever block even in the block size smaller than page size scenario. So instead of not removing any extent maps at all in case the GFP glags don't allow blocking, keep removing extent maps while we don't need to reschedule. This makes it safe for the subpage case and for a future where we can process folios with a size larger than a page. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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 reStructuredText 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.