A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-30 03:27:44 -04:00
Code Issues Projects Releases Packages Wiki Activity

vfs: Implement proper O_SYNC semantics

Browse source 
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 <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Grant Grundler <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andreas Dilger <[email protected]>
Acked-by: Trond Myklebust <[email protected]>
Acked-by: Kyle McMartin <[email protected]>
Acked-by: Ulrich Drepper <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
This commit is contained in:
Christoph Hellwig 2009-10-27 11:05:28 +01:00 • committed by Jan Kara
commit 6b2f3d1f76
24 changed files with 109 additions and 40 deletions
Download patch file Download diff file Expand all files Collapse all files

5
arch/parisc/include/asm/fcntl.h
View file

@ -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 */