commit 35851f133bf39da0e814e9681d6a7fcc62431de6
parent 49223b2df217f4c5db24126b00f82a623f0f91f7
Author: Oswald Buddenhagen <ossi@users.sf.net>
Date: Sat, 15 Sep 2012 15:15:22 +0200
add option to control amount of fsync()ing
Diffstat:
8 files changed, 50 insertions(+), 6 deletions(-)
diff --git a/NEWS b/NEWS
@@ -10,6 +10,8 @@ UIDPLUS extension (e.g., M$ Exchange).
More automatic handling of SSL certificates.
+Data safety in case of system crashes is improved.
+
[1.0.0]
Essentially a rewrite. Synchronization state storage concept, configuration
diff --git a/TODO b/TODO
@@ -1,5 +1,7 @@
find out why mutt's message size calc is confused.
+f{,data}sync() usage could be optimized by batching the calls.
+
add some marker about message being already [remotely] trashed.
real transactions would be certainly not particularly useful ...
diff --git a/src/config.c b/src/config.c
@@ -39,6 +39,7 @@ channel_conf_t *channels;
group_conf_t *groups;
int global_ops[2];
char *global_sync_state;
+int FSyncLevel = FSYNC_NORMAL;
#define ARG_OPTIONAL 0
#define ARG_REQUIRED 1
@@ -448,6 +449,16 @@ load_config( const char *where, int pseudo )
}
break;
}
+ else if (!strcasecmp( "FSync", cfile.cmd ))
+ {
+ arg = cfile.val;
+ if (!strcasecmp( "None", arg ))
+ FSyncLevel = FSYNC_NONE;
+ else if (!strcasecmp( "Normal", arg ))
+ FSyncLevel = FSYNC_NORMAL;
+ else if (!strcasecmp( "Thorough", arg ))
+ FSyncLevel = FSYNC_THOROUGH;
+ }
else if (!getopt_helper( &cfile, &gcops, global_ops, &global_sync_state ))
{
error( "%s:%d: unknown section keyword '%s'\n",
diff --git a/src/drv_maildir.c b/src/drv_maildir.c
@@ -432,7 +432,7 @@ maildir_store_uid( maildir_store_t *ctx )
n = sprintf( buf, "%d\n%d\n", ctx->gen.uidvalidity, ctx->nuid );
lseek( ctx->uvfd, 0, SEEK_SET );
- if (write( ctx->uvfd, buf, n ) != n || ftruncate( ctx->uvfd, n ) || fdatasync( ctx->uvfd )) {
+ if (write( ctx->uvfd, buf, n ) != n || ftruncate( ctx->uvfd, n ) || (FSyncLevel >= FSYNC_NORMAL && fdatasync( ctx->uvfd ))) {
error( "Maildir error: cannot write UIDVALIDITY.\n" );
return DRV_BOX_BAD;
}
@@ -1204,7 +1204,7 @@ maildir_store_msg( store_t *gctx, msg_data_t *data, int to_trash,
}
ret = write( fd, data->data, data->len );
free( data->data );
- if (ret != data->len || (ret = fsync( fd ))) {
+ if (ret != data->len || ((FSyncLevel >= FSYNC_NORMAL) && (ret = fsync( fd )))) {
if (ret < 0)
sys_error( "Maildir error: cannot write %s", buf );
else
diff --git a/src/isync.h b/src/isync.h
@@ -481,6 +481,12 @@ extern group_conf_t *groups;
extern int global_ops[2];
extern char *global_sync_state;
+#define FSYNC_NONE 0
+#define FSYNC_NORMAL 1
+#define FSYNC_THOROUGH 2
+
+extern int FSyncLevel;
+
int parse_bool( conffile_t *cfile );
int parse_int( conffile_t *cfile );
int parse_size( conffile_t *cfile );
diff --git a/src/mbsync.1 b/src/mbsync.1
@@ -20,7 +20,7 @@
\" As a special exception, mbsync may be linked with the OpenSSL library,
\" despite that library's more restrictive license.
..
-.TH mbsync 1 "2012 Aug 25"
+.TH mbsync 1 "2012 Sep 15"
..
.SH NAME
mbsync - synchronize IMAP4 and Maildir mailboxes
@@ -477,6 +477,26 @@ line, except that there newlines can be used as mailbox name separators as well.
Add the specified channels to the group. This option can be specified multiple
times within a Group.
..
+.SS Global Options
+.TP
+\fBFSync\fR {\fINone\fR|\fINormal\fR|\fIThorough\fR}
+.br
+Select the amount of forced flushing \fBmbsync\fR performs, which determines
+the level of data safety after system crashes and power outages:
+.br
+\fBNone\fR - no flushing at all. This is reasonably safe for file systems
+which are mounted with data=ordered mode.
+.br
+\fBNormal\fR - message and critical metadata writes are flushed. No data
+should be lost due to crashes, though it is still possible that messages
+are duplicated after crashes. This is the default, and is a wise choice for
+file systems mounted with data=writeback, in particular modern systems like
+ext4, btrfs and xfs. The performance impact on older file systems may be
+disproportionate.
+.br
+\fBThorough\fR - this avoids message duplication after crashes as well,
+at some additional performance cost.
+..
.SH SSL CERTIFICATES
[to be done]
..
diff --git a/src/run-tests.pl b/src/run-tests.pl
@@ -256,7 +256,9 @@ sub writecfg($$$)
open(FILE, ">", ".mbsyncrc") or
die "Cannot open .mbsyncrc.\n";
print FILE
-"MaildirStore master
+"FSync None
+
+MaildirStore master
Path ./
Inbox ./master
".shift()."
diff --git a/src/sync.c b/src/sync.c
@@ -42,7 +42,7 @@ const char *str_ms[] = { "master", "slave" }, *str_hl[] = { "push", "pull" };
void
Fclose( FILE *f, int safe )
{
- if ((safe && (fflush( f ) || fdatasync( fileno( f ) ))) || fclose( f ) == EOF) {
+ if ((safe && (fflush( f ) || (FSyncLevel >= FSYNC_NORMAL && fdatasync( fileno( f ) )))) || fclose( f ) == EOF) {
sys_error( "Error: cannot close file. Disk full?" );
exit( 1 );
}
@@ -1202,7 +1202,8 @@ box_loaded( int sts, void *aux )
cv->srec = srec;
cv->msg = tmsg;
Fprintf( svars->jfp, "# %d %d %." stringify(TUIDL) "s\n", srec->uid[M], srec->uid[S], srec->tuid );
- fdatasync( fileno( svars->jfp ) );
+ if (FSyncLevel >= FSYNC_THOROUGH)
+ fdatasync( fileno( svars->jfp ) );
debug( " -> %sing message, TUID %." stringify(TUIDL) "s\n", str_hl[t], srec->tuid );
if (copy_msg( cv ))
return;
