mainlining shenanigans
052a82d85a
As Eric reported: On xfstest generic/204 on f2fs, I'm getting a kernel BUG. allocate_segment_by_default+0x9d/0x100 [f2fs] f2fs_allocate_data_block+0x3c0/0x5c0 [f2fs] do_write_page+0x62/0x110 [f2fs] f2fs_do_write_node_page+0x2b/0xa0 [f2fs] __write_node_page+0x2ec/0x590 [f2fs] f2fs_sync_node_pages+0x756/0x7e0 [f2fs] block_operations+0x25b/0x350 [f2fs] f2fs_write_checkpoint+0x104/0x1150 [f2fs] f2fs_sync_fs+0xa2/0x120 [f2fs] f2fs_balance_fs_bg+0x33c/0x390 [f2fs] f2fs_write_node_pages+0x4c/0x1f0 [f2fs] do_writepages+0x1c/0x70 __writeback_single_inode+0x45/0x320 writeback_sb_inodes+0x273/0x5c0 wb_writeback+0xff/0x2e0 wb_workfn+0xa1/0x370 process_one_work+0x138/0x350 worker_thread+0x4d/0x3d0 kthread+0x109/0x140 The root cause of this issue is, in a very small partition, e.g. in generic/204 testcase of fstest suit, filesystem's free space is 50MB, so at most we can write 12800 inline inode with command: `echo XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > $SCRATCH_MNT/$i`, then filesystem will have: - 12800 dirty inline data page - 12800 dirty inode page - and 12800 dirty imeta (dirty inode) When we flush node-inode's page cache, we can also flush inline data with each inode page, however it will run out-of-free-space in device, then once it triggers checkpoint, there is no room for huge number of imeta, at this time, GC is useless, as there is no dirty segment at all. In order to fix this, we try to recognize inode page during node_inode's page flushing, and update inode page from dirty inode, so that later another imeta (dirty inode) flush can be avoided. Reported-and-tested-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> |
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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.