kernel/linux.git/include/linux/pipe_fs_i.h, branch v6.12.80

fs/pipe: move check to pipe_has_watch_queue()

2023-10-19T09:02:47+00:00

This declutters the code by reducing the number of #ifdefs and makes the watch_queue checks simpler. This has no runtime effect; the machine code is identical. Signed-off-by: Max Kellermann Message-Id: <20230921075755.1378787-2-max.kellermann@ionos.com> Reviewed-by: David Howells Signed-off-by: Christian Brauner

pipe: reduce padding in struct pipe_inode_info

2023-10-19T09:02:47+00:00

This has no effect on 64 bit because there are 10 32-bit integers surrounding the two bools, but on 32 bit architectures, this reduces the struct size by 4 bytes by merging the two bools into one word. Signed-off-by: Max Kellermann Message-Id: <20230921075755.1378787-1-max.kellermann@ionos.com> Signed-off-by: Christian Brauner

pipe: Pass argument of pipe_fcntl as int

2023-07-10T12:36:12+00:00

The interface for fcntl expects the argument passed for the command F_SETPIPE_SZ to be of type int. The current code wrongly treats it as a long. In order to avoid access to undefined bits, we should explicitly cast the argument to int. Cc: Alexander Viro Cc: Christian Brauner Cc: Jeff Layton Cc: Chuck Lever Cc: Kevin Brodsky Cc: Vincenzo Frascino Cc: Szabolcs Nagy Cc: "Theodore Ts'o" Cc: David Laight Cc: Mark Rutland Cc: linux-fsdevel@vger.kernel.org Cc: linux-morello@op-lists.linaro.org Signed-off-by: Luca Vizzarro Message-Id: <20230414152459.816046-4-Luca.Vizzarro@arm.com> Signed-off-by: Christian Brauner

fs: pipe: reveal missing function protoypes

2023-05-17T07:16:59+00:00

A couple of functions from fs/pipe.c are used both internally and for the watch queue code, but the declaration is only visible when the latter is enabled: fs/pipe.c:1254:5: error: no previous prototype for 'pipe_resize_ring' fs/pipe.c:758:15: error: no previous prototype for 'account_pipe_buffers' fs/pipe.c:764:6: error: no previous prototype for 'too_many_pipe_buffers_soft' fs/pipe.c:771:6: error: no previous prototype for 'too_many_pipe_buffers_hard' fs/pipe.c:777:6: error: no previous prototype for 'pipe_is_unprivileged_user' Make the visible unconditionally to avoid these warnings. Fixes: c73be61cede5 ("pipe: Add general notification queue support") Signed-off-by: Arnd Bergmann Message-Id: <20230516195629.551602-1-arnd@kernel.org> Signed-off-by: Christian Brauner

splice: Add a func to do a splice from a buffered file without ITER_PIPE

2023-02-20T23:25:43+00:00

Provide a function to do splice read from a buffered file, pulling the folios out of the pagecache directly by calling filemap_get_pages() to do any required reading and then pasting the returned folios into the pipe. A helper function is provided to do the actual folio pasting and will handle multipage folios by splicing as many of the relevant subpages as will fit into the pipe. The code is loosely based on filemap_read() and might belong in mm/filemap.c with that as it needs to use filemap_get_pages(). Signed-off-by: David Howells Reviewed-by: Jens Axboe cc: Christoph Hellwig cc: Al Viro cc: David Hildenbrand cc: John Hubbard cc: linux-mm@kvack.org cc: linux-block@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French

ITER_PIPE: fold data_start() and pipe_space_for_user() together

2022-08-09T02:37:19+00:00

All their callers are next to each other; all of them want the total amount of pages and, possibly, the offset in the partial final buffer. Combine into a new helper (pipe_npages()), fix the bogosity in pipe_space_for_user(), while we are at it. Signed-off-by: Al Viro

fix short copy handling in copy_mc_pipe_to_iter()

2022-06-28T21:37:11+00:00

Unlike other copying operations on ITER_PIPE, copy_mc_to_iter() can result in a short copy. In that case we need to trim the unused buffers, as well as the length of partially filled one - it's not enough to set ->head, ->iov_offset and ->count to reflect how much had we copied. Not hard to fix, fortunately... I'd put a helper (pipe_discard_from(pipe, head)) into pipe_fs_i.h, rather than iov_iter.c - it has nothing to do with iov_iter and having it will allow us to avoid an ugly kludge in fs/splice.c. We could put it into lib/iov_iter.c for now and move it later, but I don't see the point going that way... Cc: stable@kernel.org # 4.19+ Fixes: ca146f6f091e "lib/iov_iter: Fix pipe handling in _copy_to_iter_mcsafe()" Reviewed-by: Jeff Layton Reviewed-by: Christian Brauner (Microsoft) Signed-off-by: Al Viro

pipe: make poll_usage boolean and annotate its access

2022-04-29T21:38:01+00:00

Patch series "Fix data-races around epoll reported by KCSAN." This series suppresses a false positive KCSAN's message and fixes a real data-race. This patch (of 2): pipe_poll() runs locklessly and assigns 1 to poll_usage. Once poll_usage is set to 1, it never changes in other places. However, concurrent writes of a value trigger KCSAN, so let's make KCSAN happy. BUG: KCSAN: data-race in pipe_poll / pipe_poll write to 0xffff8880042f6678 of 4 bytes by task 174 on cpu 3: pipe_poll (fs/pipe.c:656) ep_item_poll.isra.0 (./include/linux/poll.h:88 fs/eventpoll.c:853) do_epoll_wait (fs/eventpoll.c:1692 fs/eventpoll.c:1806 fs/eventpoll.c:2234) __x64_sys_epoll_wait (fs/eventpoll.c:2246 fs/eventpoll.c:2241 fs/eventpoll.c:2241) do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:113) write to 0xffff8880042f6678 of 4 bytes by task 177 on cpu 1: pipe_poll (fs/pipe.c:656) ep_item_poll.isra.0 (./include/linux/poll.h:88 fs/eventpoll.c:853) do_epoll_wait (fs/eventpoll.c:1692 fs/eventpoll.c:1806 fs/eventpoll.c:2234) __x64_sys_epoll_wait (fs/eventpoll.c:2246 fs/eventpoll.c:2241 fs/eventpoll.c:2241) do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:113) Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 177 Comm: epoll_race Not tainted 5.17.0-58927-gf443e374ae13 #6 Hardware name: Red Hat KVM, BIOS 1.11.0-2.amzn2 04/01/2014 Link: https://lkml.kernel.org/r/20220322002653.33865-1-kuniyu@amazon.co.jp Link: https://lkml.kernel.org/r/20220322002653.33865-2-kuniyu@amazon.co.jp Fixes: 3b844826b6c6 ("pipe: avoid unnecessary EPOLLET wakeups under normal loads") Signed-off-by: Kuniyuki Iwashima Cc: Alexander Duyck Cc: Al Viro Cc: Davidlohr Bueso Cc: Kuniyuki Iwashima Cc: "Soheil Hassas Yeganeh" Cc: "Sridhar Samudrala" Signed-off-by: Andrew Morton

fs: move pipe sysctls to is own file

2022-01-22T06:33:36+00:00

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. So move the pipe sysctls to its own file. Link: https://lkml.kernel.org/r/20211129205548.605569-10-mcgrof@kernel.org Signed-off-by: Luis Chamberlain Cc: Al Viro Cc: Andy Shevchenko Cc: Antti Palosaari Cc: Eric Biederman Cc: Iurii Zaikin Cc: "J. Bruce Fields" Cc: Jeff Layton Cc: Kees Cook Cc: Lukas Middendorf Cc: Stephen Kitt Cc: Xiaoming Ni Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

pipe: avoid unnecessary EPOLLET wakeups under normal loads

2021-08-18T18:39:46+00:00

I had forgotten just how sensitive hackbench is to extra pipe wakeups, and commit 3a34b13a88ca ("pipe: make pipe writes always wake up readers") ended up causing a quite noticeable regression on larger machines. Now, hackbench isn't necessarily a hugely meaningful benchmark, and it's not clear that this matters in real life all that much, but as Mel points out, it's used often enough when comparing kernels and so the performance regression shows up like a sore thumb. It's easy enough to fix at least for the common cases where pipes are used purely for data transfer, and you never have any exciting poll usage at all. So set a special 'poll_usage' flag when there is polling activity, and make the ugly "EPOLLET has crazy legacy expectations" semantics explicit to only that case. I would love to limit it to just the broken EPOLLET case, but the pipe code can't see the difference between epoll and regular select/poll, so any non-read/write waiting will trigger the extra wakeup behavior. That is sufficient for at least the hackbench case. Apart from making the odd extra wakeup cases more explicitly about EPOLLET, this also makes the extra wakeup be at the _end_ of the pipe write, not at the first write chunk. That is actually much saner semantics (as much as you can call any of the legacy edge-triggered expectations for EPOLLET "sane") since it means that you know the wakeup will happen once the write is done, rather than possibly in the middle of one. [ For stable people: I'm putting a "Fixes" tag on this, but I leave it up to you to decide whether you actually want to backport it or not. It likely has no impact outside of synthetic benchmarks - Linus ] Link: https://lore.kernel.org/lkml/20210802024945.GA8372@xsang-OptiPlex-9020/ Fixes: 3a34b13a88ca ("pipe: make pipe writes always wake up readers") Reported-by: kernel test robot Tested-by: Sandeep Patil Tested-by: Mel Gorman Signed-off-by: Linus Torvalds