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c3aab9a0bd
Functions like filemap_write_and_wait_range() should do nothing if inode has no dirty pages or pages currently under writeback. But they anyway construct struct writeback_control and this does some atomic operations if CONFIG_CGROUP_WRITEBACK=y - on fast path it locks inode->i_lock and updates state of writeback ownership, on slow path might be more work. Current this path is safely avoided only when inode mapping has no pages. For example generic_file_read_iter() calls filemap_write_and_wait_range() at each O_DIRECT read - pretty hot path. This patch skips starting new writeback if mapping has no dirty tags set. If writeback is already in progress filemap_write_and_wait_range() will wait for it. Link: http://lkml.kernel.org/r/156378816804.1087.8607636317907921438.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
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| 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 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.