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Inside lock_delalloc_folios(), there are several problems related to
sector size < page size handling:
- Set the writer locks without checking if the folio is still valid
We call btrfs_folio_start_writer_lock() just like it's folio_lock().
But since the folio may not even be the folio of the current mapping,
we can easily screw up the folio->private.
- The range is not clamped inside the page
This means we can over write other bitmaps if the start/len is not
properly handled, and trigger the btrfs_subpage_assert().
- @processed_end is always rounded up to page end
If the delalloc range is not page aligned, and we need to retry
(returning -EAGAIN), then we will unlock to the page end.
Thankfully this is not a huge problem, as now
btrfs_folio_end_writer_lock() can handle range larger than the locked
range, and only unlock what is already locked.
Fix all these problems by:
- Lock and check the folio first, then call
btrfs_folio_set_writer_lock()
So that if we got a folio not belonging to the inode, we won't
touch folio->private.
- Properly truncate the range inside the page
- Update @processed_end to the locked range end
Fixes:
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||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.