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9a42891c35
With the following two conditions, bio will be lost:
1) blk plug is not enabled, for example, __blkdev_direct_IO_simple() and
__blkdev_direct_IO_async();
2) bio plug is enabled, for example write IO for raid1/raid10 while
bitmap is enabled;
Root cause is that blk_finish_plug() will add the bio to
curent->bio_list, while such bio will not be handled:
__submit_bio_noacct
current->bio_list = bio_list_on_stack;
blk_start_plug
do {
dm_submit_bio
md_handle_request
raid10_write_request
-> generate new bio for underlying disks
raid1_add_bio_to_plug -> bio is added to plug
} while ((bio = bio_list_pop(&bio_list_on_stack[0])))
-> previous bio are all handled
blk_finish_plug
raid10_unplug
raid1_submit_write
submit_bio_noacct
if (current->bio_list)
bio_list_add(¤t->bio_list[0], bio)
-> add new bio
current->bio_list = NULL
-> new bio is lost
Fix the problem by moving the plug into the while loop, so that
current->bio_list will still be handled after blk_finish_plug().
By the way, enable plug for raid1/raid10 in this case will also prevent
delay IO handling into daemon thread, which should also improve IO
performance.
Fixes:
|
||
|---|---|---|
| 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.