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authorChristoph Hellwig <hch@lst.de>2009-10-27 11:05:28 +0100
committerJan Kara <jack@suse.cz>2009-12-10 15:02:50 +0100
commit6b2f3d1f769be5779b479c37800229d9a4809fc3 (patch)
tree046ef6736ec6c25ab1c68741ba715d13645af336 /arch
parent59bc055211b8d266ab6089158058bf8268e02006 (diff)
downloadlinux-stericsson-6b2f3d1f769be5779b479c37800229d9a4809fc3.tar.gz
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')
-rw-r--r--arch/alpha/include/asm/fcntl.h19
-rw-r--r--arch/blackfin/include/asm/fcntl.h2
-rw-r--r--arch/mips/include/asm/fcntl.h17
-rw-r--r--arch/mips/kernel/kspd.c1
-rw-r--r--arch/mips/loongson/common/mem.c2
-rw-r--r--arch/mips/mm/cache.c2
-rw-r--r--arch/parisc/include/asm/fcntl.h5
-rw-r--r--arch/sparc/include/asm/fcntl.h19
-rw-r--r--arch/x86/mm/pat.c3
9 files changed, 54 insertions, 16 deletions
diff --git a/arch/alpha/include/asm/fcntl.h b/arch/alpha/include/asm/fcntl.h
index 25da0017ec87..21b1117a0c61 100644
--- a/arch/alpha/include/asm/fcntl.h
+++ b/arch/alpha/include/asm/fcntl.h
@@ -1,8 +1,6 @@
#ifndef _ALPHA_FCNTL_H
#define _ALPHA_FCNTL_H
-/* open/fcntl - O_SYNC is only implemented on blocks devices and on files
- located on an ext2 file system */
#define O_CREAT 01000 /* not fcntl */
#define O_TRUNC 02000 /* not fcntl */
#define O_EXCL 04000 /* not fcntl */
@@ -10,13 +8,28 @@
#define O_NONBLOCK 00004
#define O_APPEND 00010
-#define O_SYNC 040000
+#define O_DSYNC 040000 /* used to be O_SYNC, see below */
#define O_DIRECTORY 0100000 /* must be a directory */
#define O_NOFOLLOW 0200000 /* don't follow links */
#define O_LARGEFILE 0400000 /* will be set by the kernel on every open */
#define O_DIRECT 02000000 /* direct disk access - should check with OSF/1 */
#define O_NOATIME 04000000
#define O_CLOEXEC 010000000 /* set close_on_exec */
+/*
+ * 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.
+ */
+#define __O_SYNC 020000000
+#define O_SYNC (__O_SYNC|O_DSYNC)
#define F_GETLK 7
#define F_SETLK 8
diff --git a/arch/blackfin/include/asm/fcntl.h b/arch/blackfin/include/asm/fcntl.h
index 8727b2b382f1..251c911d59c1 100644
--- a/arch/blackfin/include/asm/fcntl.h
+++ b/arch/blackfin/include/asm/fcntl.h
@@ -7,8 +7,6 @@
#ifndef _BFIN_FCNTL_H
#define _BFIN_FCNTL_H
-/* open/fcntl - O_SYNC is only implemented on blocks devices and on files
- located on an ext2 file system */
#define O_DIRECTORY 040000 /* must be a directory */
#define O_NOFOLLOW 0100000 /* don't follow links */
#define O_DIRECT 0200000 /* direct disk access hint - currently ignored */
diff --git a/arch/mips/include/asm/fcntl.h b/arch/mips/include/asm/fcntl.h
index 2a52333a062d..7c6681aa2ab8 100644
--- a/arch/mips/include/asm/fcntl.h
+++ b/arch/mips/include/asm/fcntl.h
@@ -10,7 +10,7 @@
#define O_APPEND 0x0008
-#define O_SYNC 0x0010
+#define O_DSYNC 0x0010 /* used to be O_SYNC, see below */
#define O_NONBLOCK 0x0080
#define O_CREAT 0x0100 /* not fcntl */
#define O_TRUNC 0x0200 /* not fcntl */
@@ -18,6 +18,21 @@
#define O_NOCTTY 0x0800 /* not fcntl */
#define FASYNC 0x1000 /* fcntl, for BSD compatibility */
#define O_LARGEFILE 0x2000 /* allow large file opens */
+/*
+ * 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.
+ */
+#define __O_SYNC 0x4000
+#define O_SYNC (__O_SYNC|O_DSYNC)
#define O_DIRECT 0x8000 /* direct disk access hint */
#define F_GETLK 14
diff --git a/arch/mips/kernel/kspd.c b/arch/mips/kernel/kspd.c
index ad4e017ed2f3..80e2ba694bab 100644
--- a/arch/mips/kernel/kspd.c
+++ b/arch/mips/kernel/kspd.c
@@ -82,6 +82,7 @@ static int sp_stopping;
#define MTSP_O_SHLOCK 0x0010
#define MTSP_O_EXLOCK 0x0020
#define MTSP_O_ASYNC 0x0040
+/* XXX: check which of these is actually O_SYNC vs O_DSYNC */
#define MTSP_O_FSYNC O_SYNC
#define MTSP_O_NOFOLLOW 0x0100
#define MTSP_O_SYNC 0x0080
diff --git a/arch/mips/loongson/common/mem.c b/arch/mips/loongson/common/mem.c
index 7c92f79b6480..e94ef158f980 100644
--- a/arch/mips/loongson/common/mem.c
+++ b/arch/mips/loongson/common/mem.c
@@ -26,7 +26,7 @@ void __init prom_init_memory(void)
/* override of arch/mips/mm/cache.c: __uncached_access */
int __uncached_access(struct file *file, unsigned long addr)
{
- if (file->f_flags & O_SYNC)
+ if (file->f_flags & O_DSYNC)
return 1;
return addr >= __pa(high_memory) ||
diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index 694d51f523d1..102b2dfa542a 100644
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -194,7 +194,7 @@ void __devinit cpu_cache_init(void)
int __weak __uncached_access(struct file *file, unsigned long addr)
{
- if (file->f_flags & O_SYNC)
+ if (file->f_flags & O_DSYNC)
return 1;
return addr >= __pa(high_memory);
diff --git a/arch/parisc/include/asm/fcntl.h b/arch/parisc/include/asm/fcntl.h
index 1e1c824764ee..f357fc693c89 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 */
diff --git a/arch/sparc/include/asm/fcntl.h b/arch/sparc/include/asm/fcntl.h
index d4d9c9d852c3..3b9cfb39175e 100644
--- a/arch/sparc/include/asm/fcntl.h
+++ b/arch/sparc/include/asm/fcntl.h
@@ -1,14 +1,12 @@
#ifndef _SPARC_FCNTL_H
#define _SPARC_FCNTL_H
-/* open/fcntl - O_SYNC is only implemented on blocks devices and on files
- located on an ext2 file system */
#define O_APPEND 0x0008
#define FASYNC 0x0040 /* fcntl, for BSD compatibility */
#define O_CREAT 0x0200 /* not fcntl */
#define O_TRUNC 0x0400 /* not fcntl */
#define O_EXCL 0x0800 /* not fcntl */
-#define O_SYNC 0x2000
+#define O_DSYNC 0x2000 /* used to be O_SYNC, see below */
#define O_NONBLOCK 0x4000
#if defined(__sparc__) && defined(__arch64__)
#define O_NDELAY 0x0004
@@ -20,6 +18,21 @@
#define O_DIRECT 0x100000 /* direct disk access hint */
#define O_NOATIME 0x200000
#define O_CLOEXEC 0x400000
+/*
+ * 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.
+ */
+#define __O_SYNC 0x800000
+#define O_SYNC (__O_SYNC|O_DSYNC)
#define F_GETOWN 5 /* for sockets. */
#define F_SETOWN 6 /* for sockets. */
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 66b55d6e69ed..ae9648eb1c7f 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -704,9 +704,8 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
if (!range_is_allowed(pfn, size))
return 0;
- if (file->f_flags & O_SYNC) {
+ if (file->f_flags & O_DSYNC)
flags = _PAGE_CACHE_UC_MINUS;
- }
#ifdef CONFIG_X86_32
/*