From: Andreas Dilger <adilger@sun.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
akpm@linux-foundation.org, drepper@redhat.com,
viro@zeniv.linux.org.uk, kyle@mcmartin.ca
Subject: Re: [PATCH 18/16] implement posix O_SYNC and O_DSYNC semantics
Date: Fri, 11 Sep 2009 01:07:55 +0200 [thread overview]
Message-ID: <20090910230755.GQ9372@webber.adilger.int> (raw)
In-Reply-To: <20090910202521.GA20261@lst.de>
On Sep 10, 2009 22:25 +0200, Christoph Hellwig wrote:
> +/*
> + * Before Linux 2.6.32 only O_DSYNC semantics were implemented, but using
> + * the O_SYNC flag. We continue to use the existing numerical value
> + * for O_DSYNC semantics now, but using the correct symbolic name for it.
> + * This new value is used to request true Posix O_SYNC semantics. It is
> + * defined in this strange way to make sure applications compiled against
> + * new headers get at least O_DSYNC semantics on older kernels.
> + *
> + * This has the nice side-effect that we can simply test for O_DSYNC
> + * wherever we do not care if O_DSYNC or O_SYNC is used.
> +
> + * Note: __O_SYNC must never be used directly.
Doesn't it make sense that applications that actually know what they are
doing may want to start using __O_SYNC directly at some point in the
future? It makes sense to code the kernel to handle both of these flags
appropriately (i.e. if __O_SYNC is set, but O_DSYNC is not then treat
this as the proper "O_SYNC").
> Index: linux-2.6/arch/alpha/include/asm/fcntl.h
> ===================================================================
> --- linux-2.6.orig/arch/alpha/include/asm/fcntl.h 2009-09-10 16:31:47.720004025 -0300
> +++ linux-2.6/arch/alpha/include/asm/fcntl.h 2009-09-10 16:33:55.087294444 -0300
> #define O_CLOEXEC 010000000 /* set close_on_exec */
> +#define __O_SYNC 010000000
These two flags have the same value...
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
next prev parent reply other threads:[~2009-09-10 23:08 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-02 13:59 [PATCH 0/16] Make O_SYNC handling use standard syncing path (version 4) Jan Kara
2009-09-02 13:59 ` [PATCH 01/16] vfs: Introduce filemap_fdatawait_range Jan Kara
2009-09-02 13:59 ` [PATCH 02/16] vfs: Export __generic_file_aio_write() and add some comments Jan Kara
2009-09-02 13:59 ` [PATCH 03/16] vfs: Remove syncing from generic_file_direct_write() and generic_file_buffered_write() Jan Kara
2009-09-02 13:59 ` [PATCH 04/16] pohmelfs: Use __generic_file_aio_write instead of generic_file_aio_write_nolock Jan Kara
2009-09-02 13:59 ` [PATCH 05/16] ocfs2: " Jan Kara
2009-09-02 13:59 ` [PATCH 06/16] vfs: Rename generic_file_aio_write_nolock Jan Kara
2009-09-02 21:47 ` Christoph Hellwig
2009-09-03 10:24 ` Jan Kara
2009-09-03 15:37 ` Christoph Hellwig
2009-09-02 13:59 ` [PATCH 07/16] vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode Jan Kara
2009-09-02 13:59 ` [PATCH 08/16] ext2: Update comment about generic_osync_inode Jan Kara
2009-09-02 13:59 ` [PATCH 09/16] ext3: Remove syncing logic from ext3_file_write Jan Kara
2009-09-02 13:59 ` [PATCH 10/16] ext4: Remove syncing logic from ext4_file_write Jan Kara
2009-09-02 13:59 ` [PATCH 11/16] ntfs: Use new syncing helpers and update comments Jan Kara
2009-09-02 13:59 ` [PATCH 12/16] ocfs2: Update syncing after splicing to match generic version Jan Kara
2009-09-02 13:59 ` [PATCH 13/16] xfs: Convert sync_page_range() to simple filemap_write_and_wait_range() Jan Kara
2009-09-02 13:59 ` [PATCH 14/16] pohmelfs: Use new syncing helper Jan Kara
2009-09-02 13:59 ` [PATCH 15/16] fat: Opencode sync_page_range_nolock() Jan Kara
2009-09-02 13:59 ` [PATCH 16/16] vfs: Remove generic_osync_inode() and sync_page_range{_nolock}() Jan Kara
2009-09-02 14:16 ` [PATCH 0/16] Make O_SYNC handling use standard syncing path (version 4) Christoph Hellwig
2009-09-02 22:18 ` [PATCH] fsync: wait for data writeout completion before calling ->fsync Christoph Hellwig
2009-09-02 22:37 ` Joel Becker
2009-09-03 10:47 ` Jan Kara
2009-09-03 15:39 ` Christoph Hellwig
2009-09-10 20:25 ` [PATCH 18/16] implement posix O_SYNC and O_DSYNC semantics Christoph Hellwig
2009-09-10 20:38 ` Trond Myklebust
2009-09-10 20:40 ` Christoph Hellwig
2009-09-10 20:43 ` Trond Myklebust
2009-09-10 20:44 ` Christoph Hellwig
2009-09-10 23:07 ` Andreas Dilger [this message]
2009-09-10 23:18 ` Christoph Hellwig
2009-09-11 19:16 ` [PATCHv2 " Christoph Hellwig
2009-09-14 16:54 ` Jan Kara
2009-09-14 17:02 ` Christoph Hellwig
2009-09-15 13:12 ` [PATCH] " Christoph Hellwig
2009-09-15 14:10 ` Jan Kara
2009-09-15 14:50 ` Ulrich Drepper
2009-09-17 17:16 ` Christoph Hellwig
2009-09-17 21:03 ` Kyle McMartin
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