Fork of alistair23 Linux kernel for reMarkable from https://github.com/alistair23/linux
ad6672bbc5
For the case when sbi->segs_per_sec > 1 with lfs mode, take section:segment = 5 for example, if the section prefree_map is ...previous section | current section (1 1 0 1 1) | next section..., then the start = x, end = x + 1, after start = start_segno + sbi->segs_per_sec, start = x + 5, then it will skip x + 3 and x + 4, but their bitmap is still set, which will cause duplicated f2fs_issue_discard of this same section in the next write_checkpoint: round 1: section bitmap : 1 1 1 1 1, all valid, prefree_map: 0 0 0 0 0 then rm data block NO.2, block NO.2 becomes invalid, prefree_map: 0 0 1 0 0 write_checkpoint: section bitmap: 1 1 0 1 1, prefree_map: 0 0 0 0 0, prefree of NO.2 is cleared, and no discard issued round 2: rm data block NO.0, NO.1, NO.3, NO.4 all invalid, but prefree bit of NO.2 is set and cleared in round 1, then prefree_map: 1 1 0 1 1 write_checkpoint: section bitmap: 0 0 0 0 0, prefree_map: 0 0 0 1 1, no valid blocks of this section, so discard issued, but this time prefree bit of NO.3 and NO.4 is skipped due to start = start_segno + sbi->segs_per_sec; round 3: write_checkpoint: section bitmap: 0 0 0 0 0, prefree_map: 0 0 0 1 1 -> 0 0 0 0 0, no valid blocks of this section, so discard issued, this time prefree bit of NO.3 and NO.4 is cleared, but the discard of this section is sent again... To fix this problem, we can align the start and end value to section boundary for fstrim and real-time discard operation, and decide to issue discard only when the whole section is invalid, which can issue discard aligned to section size as much as possible and avoid redundant discard. Signed-off-by: Yunlong Song <yunlong.song@huawei.com> Signed-off-by: Chao Yu <yuchao0@huawei.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> |
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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.
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.