Tomo, Please find attached a patch that adds a new argument to tgtimg to allow to create thin-provisioned files. The default for tgtimg is to fully allocate all device files it creates. Using this flag allows to create a "sparse" file for use by the LUN. regards ronnie sahlberg
Attachment:
0001-TGTIMG-Add-support-for-thin-provisioning.patch.gz
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From fc6859e6ab9dea7bbf71a8f411519dbf5f02f0ef Mon Sep 17 00:00:00 2001
From: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
Date: Fri, 30 Mar 2012 16:46:38 +1100
Subject: [PATCH 1/2] TGTIMG: Add support for thin-provisioning
A new flag --ting-provisioning is added to the tgtimg command.
When used this flag will create a sparse file without any
allocation guarantee.
It will also verify that FALLOC_FL_PUNCH_HOLE works.
If such files are created, a future patch to tgtd will add
support for the UNMAP command that is used by initiators to
release blocks that are no longer in use.
Signed-off-by: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
---
doc/tgtimg.8.xml | 22 ++++++++++++++++++++++
usr/tgtimg.c | 45 ++++++++++++++++++++++++++++++++++++---------
2 files changed, 58 insertions(+), 9 deletions(-)
diff --git a/doc/tgtimg.8.xml b/doc/tgtimg.8.xml
index 5a787af..e067db0 100644
--- a/doc/tgtimg.8.xml
+++ b/doc/tgtimg.8.xml
@@ -21,6 +21,7 @@
<arg choice="opt">-s --size <size></arg>
<arg choice="opt">-t --type <media-type></arg>
<arg choice="opt">-f --file <path></arg>
+ <arg choice="opt">-T --thin-provisioning</arg>
</cmdsynopsis>
<cmdsynopsis>
<command>tgtimg --help</command>
@@ -126,6 +127,27 @@ Supported media types for tape devices are :
</listitem>
</varlistentry>
+ <varlistentry><term><option>-T, --thin-provisioning</option></term>
+ <listitem>
+ <para>
+ This argument makes the allocation of the image format use
+ thin-provisioning. This means that the file created will be a
+ sparse file that will allocate blocks from the filesystem on demand.
+ </para>
+ <para>
+ Be careful when using thin-provisioning. If the filesystem
+ fills up a iSCSI write to a thin-provisioned LUN
+ can fail. Initiators generally do not handle "out of space" errors
+ gracefully.
+ </para>
+ <para>
+ Thin-provisioning uses FALLOC_FL_PUNCH_HOLE which is only available
+ on some linux filesystems. Thin-provisioning can only be used for
+ DISK images.
+ </para>
+ </listitem>
+ </varlistentry>
+
</variablelist>
</refsect1>
diff --git a/usr/tgtimg.c b/usr/tgtimg.c
index f4388d9..bb417fe 100644
--- a/usr/tgtimg.c
+++ b/usr/tgtimg.c
@@ -1,5 +1,5 @@
/*
- * Create blank media files for bs_tape backing store
+ * Create media files for TGTD devices
*
* Copyright (C) 2008 Mark Harvey markh794@xxxxxxxxx
*
@@ -22,6 +22,7 @@
#define _XOPEN_SOURCE 600
#include <errno.h>
#include <fcntl.h>
+#include <linux/falloc.h>
#include <getopt.h>
#include <inttypes.h>
#include <stdio.h>
@@ -59,6 +60,7 @@ struct option const long_options[] = {
{"size", required_argument, NULL, 's'},
{"type", required_argument, NULL, 't'},
{"file", required_argument, NULL, 'f'},
+ {"thin-provisioning", no_argument, NULL, 'T'},
{NULL, 0, NULL, 0},
};
@@ -71,7 +73,7 @@ static void usage(int status)
printf("\
Linux SCSI Target Framework Image File Utility, version %s\n\
\n\
- --op new --device-type tape --barcode=[code] --size=[size] --type=[type] --file=[path]\n\
+ --op new --device-type tape --barcode=[code] --size=[size] --type=[type] --file=[path] [--thin-provisioning]\n\
create a new tape image file.\n\
[code] is a string of chars.\n\
[size] is media size(in megabytes).\n\
@@ -83,6 +85,7 @@ Linux SCSI Target Framework Image File Utility, version %s\n\
--op show --device-type tape --file=[path]\n\
dump the tape image file contents.\n\
[path] is the tape image file\n\
+ --thin-provisioning create a sparse file for the media\n\
--help display this help and exit\n\
\n\
Report bugs to <stgt@xxxxxxxxxxxxxxx>.\n", TGT_VERSION);
@@ -414,7 +417,7 @@ static int mmc_ops(int op, char *path, char *media_type)
return 0;
}
-static int sbc_new(int op, char *path, char *capacity, char *media_type)
+static int sbc_new(int op, char *path, char *capacity, char *media_type, int thin)
{
int fd;
@@ -438,9 +441,29 @@ static int sbc_new(int op, char *path, char *capacity, char *media_type)
perror("Failed creating file");
exit(2);
}
- if (posix_fallocate(fd, 0, size*1024*1024LL) == -1) {
- perror("posix_fallocate failed.");
- exit(3);
+ if (thin) {
+#ifdef FALLOC_FL_PUNCH_HOLE
+ if (ftruncate(fd, size*1024*1024LL) != 0) {
+ perror("Failed to set file size");
+ exit(6);
+ }
+ if (fallocate(fd,
+ FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+ 0, size*1024*1024LL) != 0) {
+ perror("Thin provisioning not available on"
+ " this file");
+ exit(5);
+ }
+#else
+ perror("This version of tgtimg is not compiled "
+ "with thin-provisioning support.");
+ exit(6);
+#endif
+ } else {
+ if (posix_fallocate(fd, 0, size*1024*1024LL) == -1) {
+ perror("posix_fallocate failed.");
+ exit(3);
+ }
}
free(buf);
@@ -456,7 +479,7 @@ static int sbc_new(int op, char *path, char *capacity, char *media_type)
return 0;
}
-static int sbc_ops(int op, char *path, char *capacity, char *media_type)
+static int sbc_ops(int op, char *path, char *capacity, char *media_type, int thin)
{
if (op == OP_NEW) {
if (!media_type) {
@@ -471,7 +494,7 @@ static int sbc_ops(int op, char *path, char *capacity, char *media_type)
eprintf("Missing the capacity param\n");
usage(1);
}
- return sbc_new(op, path, capacity, media_type);
+ return sbc_new(op, path, capacity, media_type, thin);
} else {
eprintf("unknown the operation type\n");
usage(1);
@@ -489,6 +512,7 @@ int main(int argc, char **argv)
int dev_type = TYPE_TAPE;
int op = -1;
char *path = NULL;
+ int thin = 0;
while ((ch = getopt_long(argc, argv, short_options,
long_options, &longindex)) >= 0) {
@@ -514,6 +538,9 @@ int main(int argc, char **argv)
case 'h':
usage(0);
break;
+ case 'T':
+ thin = 1;
+ break;
default:
eprintf("unrecognized option '%s'\n", optarg);
usage(1);
@@ -543,7 +570,7 @@ int main(int argc, char **argv)
mmc_ops(op, path, media_type);
break;
case TYPE_DISK:
- sbc_ops(op, path, media_capacity, media_type);
+ sbc_ops(op, path, media_capacity, media_type, thin);
break;
default:
eprintf("unsupported the device type operation\n");
--
1.7.3.1
