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On unix, always use fdatasync() instead of fsync() when available, even if

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the file size changes, since (we are told) fdatasync() will automatically
flush the inode when the file size changes. (CVS 6367)

FossilOrigin-Name: 0d6b11bcf67f86e5554806869d32338e5831833e
This commit is contained in:
drh 2009-03-21 14:41:04 +00:00
parent 2b31b211c3
commit 0b647ffd47
3 changed files with 26 additions and 16 deletions
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14
manifest
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@ -1,5 +1,5 @@
C Add\sa\stest\sto\stry\sto\shit\sthe\srace-condition\sfixed\sby\s(6363).\s(CVS\s6366)
D 2009-03-20T15:16:06
C On\sunix,\salways\suse\sfdatasync()\sinstead\sof\sfsync()\swhen\savailable,\seven\sif\nthe\sfile\ssize\schanges,\ssince\s(we\sare\stold)\sfdatasync()\swill\sautomatically\nflush\sthe\sinode\swhen\sthe\sfile\ssize\schanges.\s(CVS\s6367)
D 2009-03-21T14:41:04
F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
F Makefile.in 583e87706abc3026960ed759aff6371faf84c211
F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@ -141,7 +141,7 @@ F src/os.c ed93a6b46132a602c4fd7a58142e2981c829c79d
F src/os.h fa3f4aa0119ff721a2da4b47ffd74406ac864c05
F src/os_common.h 8c61457df58f1a4bd5f5adc3e90e01b37bf7afbc
F src/os_os2.c bed77dc26e3a95ce4a204936b9a1ca6fe612fcc5
F src/os_unix.c 52352674c19688026a72cd0e8620e6a29bacba4a
F src/os_unix.c 8f6ffa95c8dc79b94565b517bc37abb426f09a23
F src/os_win.c 40636702058ed4dcd35d68151bfab56d4997cdc1
F src/pager.c 01e3facb2f7c5f307e36a0f4ed9343cf3761711a
F src/pager.h 0c9f3520c00d8a3b8e792ca56c9a11b6b02b4b0f
@ -709,7 +709,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81
F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
P a08324d16d1e9a4e7c1b294bc71fc939d173f826
R 87fff081bb6bfc825b1acb6eabea142e
U danielk1977
Z 5f0bd3312fbc59ec4534315ac49a7c31
P 4310411f5027dba18e017023e21cb09982e26752
R da4300d409cda801b0b75c2eee2c6174
U drh
Z 669efac6174bfcb881ee9f0e80879f8c

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4310411f5027dba18e017023e21cb09982e26752
0d6b11bcf67f86e5554806869d32338e5831833e

26
src/os_unix.c
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@ -43,7 +43,7 @@
** * Definitions of sqlite3_vfs objects for all locking methods
** plus implementations of sqlite3_os_init() and sqlite3_os_end().
**
** $Id: os_unix.c,v 1.242 2009/03/01 22:29:20 drh Exp $
** $Id: os_unix.c,v 1.243 2009/03/21 14:41:04 drh Exp $
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX /* This file is used on unix only */
@ -2853,6 +2853,19 @@ int sqlite3_fullsync_count = 0;
** You are strongly advised *not* to deploy with SQLITE_NO_SYNC
** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash
** or power failure will likely corrupt the database file.
**
** SQLite sets the dataOnly flag if the size of the file is unchanged.
** The idea behind dataOnly is that it should only write the file content
** to disk, not the inode. We only set dataOnly if the file size is
** unchanged since the file size is part of the inode. However,
** Ted Ts'o tells us that fdatasync() will also write the inode if the
** file size has changed. The only real difference between fdatasync()
** and fsync(), Ted tells us, is that fdatasync() will not flush the
** inode if the mtime or owner or other inode attributes have changed.
** We only care about the file size, not the other file attributes, so
** as far as SQLite is concerned, an fdatasync() is always adequate.
** So, we always use fdatasync() if it is available, regardless of
** the value of the dataOnly flag.
*/
static int full_fsync(int fd, int fullSync, int dataOnly){
int rc;
@ -2869,6 +2882,7 @@ static int full_fsync(int fd, int fullSync, int dataOnly){
UNUSED_PARAMETER(dataOnly);
#else
UNUSED_PARAMETER(fullSync);
UNUSED_PARAMETER(dataOnly);
#endif
/* Record the number of times that we do a normal fsync() and
@ -2902,16 +2916,12 @@ static int full_fsync(int fd, int fullSync, int dataOnly){
if( rc ) rc = fsync(fd);
#else
if( dataOnly ){
rc = fdatasync(fd);
rc = fdatasync(fd);
#if OS_VXWORKS
if( rc==-1 && errno==ENOTSUP ){
rc = fsync(fd);
}
#endif
}else{
if( rc==-1 && errno==ENOTSUP ){
rc = fsync(fd);
}
#endif /* OS_VXWORKS */
#endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */
if( OS_VXWORKS && rc!= -1 ){