da080fe1ba
There is a cap in btrfs in the amount of free extents that a block group can have. When it surpasses that threshold, future extents are placed into bitmaps. Instead of keeping track of if a certain bit is trimmed or not in a second bitmap, keep track of the relative state of the bitmap. With async discard, trimming bitmaps becomes a more frequent operation. As a trade off with simplicity, we keep track of if discarding a bitmap is in progress. If we fully scan a bitmap and trim as necessary, the bitmap is marked clean. This has some caveats as the min block size may skip over regions deemed too small. But this should be a reasonable trade off rather than keeping a second bitmap and making allocation paths more complex. The downside is we may overtrim, but ideally the min block size should prevent us from doing that too often and getting stuck trimming pathological cases. BTRFS_TRIM_STATE_TRIMMING is added to indicate a bitmap is in the process of being trimmed. If additional free space is added to that bitmap, the bit is cleared. A bitmap will be marked BTRFS_TRIM_STATE_TRIMMED if the trimming code was able to reach the end of it and the former is still set. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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 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.