diff options
| author | Christoph Hellwig <hch@lst.de> | 2009-10-27 11:05:28 +0100 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2009-12-10 15:02:50 +0100 |
| commit | 6b2f3d1f769be5779b479c37800229d9a4809fc3 (patch) | |
| tree | 046ef6736ec6c25ab1c68741ba715d13645af336 /arch/parisc | |
| parent | 59bc055211b8d266ab6089158058bf8268e02006 (diff) | |
vfs: Implement proper O_SYNC semantics
While Linux provided an O_SYNC flag basically since day 1, it took until
Linux 2.4.0-test12pre2 to actually get it implemented for filesystems,
since that day we had generic_osync_around with only minor changes and the
great "For now, when the user asks for O_SYNC, we'll actually give
O_DSYNC" comment. This patch intends to actually give us real O_SYNC
semantics in addition to the O_DSYNC semantics. After Jan's O_SYNC
patches which are required before this patch it's actually surprisingly
simple, we just need to figure out when to set the datasync flag to
vfs_fsync_range and when not.
This patch renames the existing O_SYNC flag to O_DSYNC while keeping it's
numerical value to keep binary compatibility, and adds a new real O_SYNC
flag. To guarantee backwards compatiblity it is defined as expanding to
both the O_DSYNC and the new additional binary flag (__O_SYNC) to make
sure we are backwards-compatible when compiled against the new headers.
This also means that all places that don't care about the differences can
just check O_DSYNC and get the right behaviour for O_SYNC, too - only
places that actuall care need to check __O_SYNC in addition. Drivers and
network filesystems have been updated in a fail safe way to always do the
full sync magic if O_DSYNC is set. The few places setting O_SYNC for
lower layers are kept that way for now to stay failsafe.
We enforce that O_DSYNC is set when __O_SYNC is set early in the open path
to make sure we always get these sane options.
Note that parisc really screwed up their headers as they already define a
O_DSYNC that has always been a no-op. We try to repair it by using it for
the new O_DSYNC and redefinining O_SYNC to send both the traditional
O_SYNC numerical value _and_ the O_DSYNC one.
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger@sun.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'arch/parisc')
| -rw-r--r-- | arch/parisc/include/asm/fcntl.h | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/parisc/include/asm/fcntl.h b/arch/parisc/include/asm/fcntl.h index 1e1c824764e..f357fc693c8 100644 --- a/arch/parisc/include/asm/fcntl.h +++ b/arch/parisc/include/asm/fcntl.h @@ -1,14 +1,13 @@ #ifndef _PARISC_FCNTL_H #define _PARISC_FCNTL_H -/* open/fcntl - O_SYNC is only implemented on blocks devices and on files - located on an ext2 file system */ #define O_APPEND 000000010 #define O_BLKSEEK 000000100 /* HPUX only */ #define O_CREAT 000000400 /* not fcntl */ #define O_EXCL 000002000 /* not fcntl */ #define O_LARGEFILE 000004000 -#define O_SYNC 000100000 +#define __O_SYNC 000100000 +#define O_SYNC (__O_SYNC|O_DSYNC) #define O_NONBLOCK 000200004 /* HPUX has separate NDELAY & NONBLOCK */ #define O_NOCTTY 000400000 /* not fcntl */ #define O_DSYNC 001000000 /* HPUX only */ |