Hello,
one small question... Will O_DSYNC flag be available in Linux?
It is available at least on AIX, and HP-UX. The difference with O_SYNC is the
same as between fsync and fdatasync.
Any comments?
--
Sincerely Yours,
Denis Perchine
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fdatasync() is the same as fsync(), in linux. until fdatasync() is
implimented (ie, syncs the data only), there's no reason to define O_DSYNC.
just use:
#ifndef O_DSYNC
# define O_DSYNC O_SYNC
#endif
On Sat, Mar 10, 2001 at 01:03:57PM +0600, Denis Perchine wrote:
> one small question... Will O_DSYNC flag be available in Linux?
> It is available at least on AIX, and HP-UX. The difference with O_SYNC is the
> same as between fsync and fdatasync.
--
Tom Vier <[email protected]>
DSA Key id 0x27371A2C
Hi,
On Wed, Mar 14, 2001 at 10:26:42PM -0500, Tom Vier wrote:
> fdatasync() is the same as fsync(), in linux.
No, in 2.4 fdatasync does the right thing and skips the inode flush if
only the timestamps have changed.
> until fdatasync() is
> implimented (ie, syncs the data only)
fdatasync is required to sync more than just the data: it has to sync
the inode too if any fields other than the timestamps have changed.
So, for appending to files or writing new files from scratch, fsync ==
fdatasync (because each write also changes the inode size). Only for
updating existing files in place does fdatasync behave differently.
> #ifndef O_DSYNC
> # define O_DSYNC O_SYNC
> #endif
2.4's O_SYNC actually does a fdatasync internally. This is also the
default behaviour of HPUX, which requires you to set a sysctl variable
if you want O_SYNC to flush timestamp changes to disk.
Cheers,
Stephen