From: Matthew Wilcox <willy@infradead.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>,
Christoph Hellwig <hch@lst.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Michael Ellerman <mpe@ellerman.id.au>,
x86@kernel.org, linux-fsdevel@vger.kernel.org,
linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org
Subject: Re: remove the last set_fs() in common code, and remove it for x86 and powerpc v2
Date: Tue, 1 Sep 2020 18:42:16 +0100 [thread overview]
Message-ID: <20200901174216.GT14765@casper.infradead.org> (raw)
In-Reply-To: <20200901172512.GI1236603@ZenIV.linux.org.uk>
On Tue, Sep 01, 2020 at 06:25:12PM +0100, Al Viro wrote:
> On Tue, Sep 01, 2020 at 07:13:00PM +0200, Christophe Leroy wrote:
>
> > 10.92% dd [kernel.kallsyms] [k] iov_iter_zero
>
> Interesting... Could you get an instruction-level profile inside iov_iter_zero(),
> along with the disassembly of that sucker?
Also, does [1] make any difference? Probably not since it's translating
O flags into IOCB flags instead of RWF flags into IOCB flags. I wonder
if there's a useful trick we can play here ... something like:
static inline int iocb_flags(struct file *file)
{
int res = 0;
if (likely(!file->f_flags & O_APPEND | O_DIRECT | O_DSYNC | __O_SYNC)) && !IS_SYNC(file->f_mapping->host))
return res;
if (file->f_flags & O_APPEND)
res |= IOCB_APPEND;
if (file->f_flags & O_DIRECT)
res |= IOCB_DIRECT;
if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))
res |= IOCB_DSYNC;
if (file->f_flags & __O_SYNC)
res |= IOCB_SYNC;
return res;
}
Can we do something like force O_DSYNC to be set if the inode IS_SYNC()
at the time of open? Or is setting the sync bit on the inode required
to affect currently-open files?
[1] https://lore.kernel.org/linux-fsdevel/95de7ce4-9254-39f1-304f-4455f66bf0f4@kernel.dk/
next prev parent reply other threads:[~2020-09-01 17:42 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 15:00 remove the last set_fs() in common code, and remove it for x86 and powerpc v2 Christoph Hellwig
2020-08-27 15:00 ` [PATCH 01/10] fs: don't allow kernel reads and writes without iter ops Christoph Hellwig
2020-08-27 15:58 ` David Laight
2020-08-29 9:23 ` 'Christoph Hellwig'
[not found] ` <20200901064849.GI4299@shao2-debian>
2020-09-01 7:08 ` [fs] ef30fb3c60: kernel write not supported for file /sys/kernel/softlockup_panic Christoph Hellwig
2020-08-27 15:00 ` [PATCH 02/10] fs: don't allow splice read/write without explicit ops Christoph Hellwig
2020-08-27 15:00 ` [PATCH 03/10] uaccess: add infrastructure for kernel builds with set_fs() Christoph Hellwig
2020-08-27 15:00 ` [PATCH 04/10] test_bitmap: skip user bitmap tests for !CONFIG_SET_FS Christoph Hellwig
2020-08-27 15:00 ` [PATCH 05/10] lkdtm: disable set_fs-based " Christoph Hellwig
2020-08-27 18:06 ` Linus Torvalds
2020-08-29 9:24 ` Christoph Hellwig
2020-09-01 18:52 ` Kees Cook
2020-09-01 18:57 ` Kees Cook
2020-09-02 8:09 ` Christoph Hellwig
2020-08-27 15:00 ` [PATCH 06/10] x86: move PAGE_OFFSET, TASK_SIZE & friends to page_{32,64}_types.h Christoph Hellwig
2020-08-27 15:00 ` [PATCH 07/10] x86: make TASK_SIZE_MAX usable from assembly code Christoph Hellwig
2020-08-27 15:00 ` [PATCH 08/10] x86: remove address space overrides using set_fs() Christoph Hellwig
2020-08-27 18:15 ` Linus Torvalds
2020-08-29 9:25 ` Christoph Hellwig
2020-08-27 15:00 ` [PATCH 09/10] powerpc: use non-set_fs based maccess routines Christoph Hellwig
2020-08-27 15:00 ` [PATCH 10/10] powerpc: remove address space overrides using set_fs() Christoph Hellwig
2020-09-02 6:15 ` Christophe Leroy
2020-09-02 12:36 ` Christoph Hellwig
2020-09-02 13:13 ` David Laight
2020-09-02 13:24 ` Christophe Leroy
2020-09-02 13:51 ` David Laight
2020-09-02 14:12 ` Christophe Leroy
2020-09-02 15:02 ` David Laight
2020-09-02 15:17 ` Christophe Leroy
2020-09-02 18:02 ` Linus Torvalds
2020-09-03 7:11 ` Christoph Hellwig
2020-09-03 7:27 ` Christophe Leroy
2020-09-03 8:55 ` Christophe Leroy
2020-09-03 7:20 ` Christophe Leroy
2020-08-27 15:31 ` remove the last set_fs() in common code, and remove it for x86 and powerpc v2 Christoph Hellwig
2020-09-01 17:13 ` Christophe Leroy
2020-09-01 17:25 ` Al Viro
2020-09-01 17:42 ` Matthew Wilcox [this message]
2020-09-01 18:39 ` Christophe Leroy
2020-09-01 19:01 ` Christophe Leroy
2020-09-02 8:10 ` Christoph Hellwig
2020-10-27 9:29 ` [PATCH 02/10] fs: don't allow splice read/write without explicit ops David Howells
2020-10-27 9:51 ` David Howells
2020-10-27 9:54 ` Christoph Hellwig
2020-10-27 10:38 ` David Howells
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