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1c2a07f598
__btrfs_free_extent() is doing two things: 1. Reduce the refs number of an extent backref Either it's an inline extent backref (inside EXTENT/METADATA item) or a keyed extent backref (SHARED_* item). We only need to locate that backref line, either reduce the number or remove the backref line completely. 2. Update the refs count in EXTENT/METADATA_ITEM During step 1), we will try to locate the EXTENT/METADATA_ITEM without triggering another btrfs_search_slot() as fast path. Only when we fail to locate that item, we will trigger another btrfs_search_slot() to get that EXTENT/METADATA_ITEM after we updated/deleted the backref line. And we have a lot of strict checks on things like refs_to_drop against extent refs and special case checks for single ref extents. There are 7 BUG_ON()s, although they're doing correct checks, they can be triggered by crafted images. This patch improves the function: - Introduce two examples to show what __btrfs_free_extent() is doing One inline backref case and one keyed case. Should cover most cases. - Kill all BUG_ON()s with proper error message and optional leaf dump - Add comment to show the overall flow Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202819 [ The report triggers one BUG_ON() in __btrfs_free_extent() ] Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Qu Wenruo <wqu@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 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.