7caadd02df
Different from non-compact indexes, several lclusters are packed
as the compact form at once and an unique base blkaddr is stored for
each pack, so each lcluster index would take less space on avarage
(e.g. 2 bytes for COMPACT_2B.) btw, that is also why BIG_PCLUSTER
switch should be consistent for compact head0/1.
Prior to big pcluster, the size of all pclusters was 1 lcluster.
Therefore, when a new HEAD lcluster was scanned, blkaddr would be
bumped by 1 lcluster. However, that way doesn't work anymore for
big pcluster since we actually don't know the compressed size of
pclusters in advance (before reading CBLKCNT lcluster).
So, instead, let blkaddr of each pack be the first pcluster blkaddr
with a valid CBLKCNT, in detail,
1) if CBLKCNT starts at the pack, this first valid pcluster is
itself, e.g.
_____________________________________________________________
|_CBLKCNT0_|_NONHEAD_| .. |_HEAD_|_CBLKCNT1_| ... |_HEAD_| ...
^ = blkaddr base ^ += CBLKCNT0 ^ += CBLKCNT1
2) if CBLKCNT doesn't start at the pack, the first valid pcluster
is the next pcluster, e.g.
_________________________________________________________
| NONHEAD_| .. |_HEAD_|_CBLKCNT0_| ... |_HEAD_|_HEAD_| ...
^ = blkaddr base ^ += CBLKCNT0
^ += 1
When a CBLKCNT is found, blkaddr will be increased by CBLKCNT
lclusters, or a new HEAD is found immediately, bump blkaddr by 1
instead (see the picture above.)
Also noted if CBLKCNT is the end of the pack, instead of storing
delta1 (distance of the next HEAD lcluster) as normal NONHEADs,
it still uses the compressed block count (delta0) since delta1
can be calculated indirectly but the block count can't.
Adjust decoding logic to fit big pcluster compact indexes as well.
Link: https://lore.kernel.org/r/20210407043927.10623-9-xiang@kernel.org
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Change-Id: Ia9dc0c8bf03b630edc4dfcedf61ef0632e1fcb05
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| android | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| techpack | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .mailmap | ||
| AndroidKernel.mk | ||
| build.config.aarch64 | ||
| build.config.allmodconfig | ||
| build.config.allmodconfig.aarch64 | ||
| build.config.allmodconfig.arm | ||
| build.config.allmodconfig.x86_64 | ||
| build.config.arm | ||
| build.config.common | ||
| build.config.gki | ||
| build.config.gki_kasan | ||
| build.config.gki_kasan.aarch64 | ||
| build.config.gki_kasan.x86_64 | ||
| build.config.gki_kprobes | ||
| build.config.gki_kprobes.aarch64 | ||
| build.config.gki_kprobes.x86_64 | ||
| build.config.gki-debug.aarch64 | ||
| build.config.gki-debug.x86_64 | ||
| build.config.gki.aarch64 | ||
| build.config.gki.x86_64 | ||
| build.config.goldfish.arm | ||
| build.config.goldfish.arm64 | ||
| build.config.goldfish.mips | ||
| build.config.goldfish.mips64 | ||
| build.config.goldfish.x86 | ||
| build.config.goldfish.x86_64 | ||
| build.config.x86_64 | ||
| COPYING | ||
| CREDITS | ||
| gen_headers_arm64.bp | ||
| gen_headers_arm.bp | ||
| Kbuild | ||
| Kconfig | ||
| kernel_headers.py | ||
| MAINTAINERS | ||
| Makefile | ||
| OWNERS | ||
| README | ||
| verity_dev_keys.x509 | ||
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.