LVM2 tools/lvmcmdline.c liblvm/lvm_base.c lib/ ...

LVM2 tools/lvmcmdline.c liblvm/lvm_base.c lib/ ...

[mornfall]

CVSROOT:	/cvs/lvm2
Module name:	LVM2
Changes by:	mornfall at sourceware.org	2011-05-07 13:50:13

Modified files:
	tools          : lvmcmdline.c 
	liblvm         : lvm_base.c 
	lib/commands   : toolcontext.c toolcontext.h 
	daemons/clvmd  : lvm-functions.c 

Log message:
	When glibc needs buffers for line buffering of input and output buffers, it
	allocates these buffers in such way it adds memory page for each such buffer
	and size of unlock memory check will mismatch by 1 or 2 pages.
	
	This happens when we print or read lines without '\n' so these buffers are
	used. To avoid this extra allocation, use setvbuf to set these bufffers ahead.
	
	Signed-off-by: Zdenek Kabelac <zkabelac@redhat.com>
	Reviewed-by: Milan Broz <mbroz@redhat.com>
	Reviewed-by: Petr Rockai <prockai@redhat.com>

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/tools/lvmcmdline.c.diff?cvsroot=lvm2&r1=1.141&r2=1.142
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/liblvm/lvm_base.c.diff?cvsroot=lvm2&r1=1.20&r2=1.21
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/lib/commands/toolcontext.c.diff?cvsroot=lvm2&r1=1.118&r2=1.119
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/lib/commands/toolcontext.h.diff?cvsroot=lvm2&r1=1.42&r2=1.43
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/daemons/clvmd/lvm-functions.c.diff?cvsroot=lvm2&r1=1.115&r2=1.116

--- LVM2/tools/lvmcmdline.c	2011/04/22 12:07:35	1.141
+++ LVM2/tools/lvmcmdline.c	2011/05/07 13:50:11	1.142
@@ -1282,7 +1282,7 @@
 	if (!udev_init_library_context())
 		stack;
 
-	if (!(cmd = create_toolcontext(0, NULL)))
+	if (!(cmd = create_toolcontext(0, NULL, 1)))
 		return_NULL;
 
 	_cmdline.arg_props = &_arg_props[0];
--- LVM2/liblvm/lvm_base.c	2010/12/20 13:28:04	1.20
+++ LVM2/liblvm/lvm_base.c	2011/05/07 13:50:11	1.21
@@ -34,7 +34,7 @@
 	/* create context */
 	/* FIXME: split create_toolcontext */
 	/* FIXME: make all globals configurable */
-	cmd = create_toolcontext(0, system_dir);
+	cmd = create_toolcontext(0, system_dir, 1);
 	if (!cmd)
 		return NULL;
 
--- LVM2/lib/commands/toolcontext.c	2011/04/29 16:23:39	1.118
+++ LVM2/lib/commands/toolcontext.c	2011/05/07 13:50:12	1.119
@@ -58,6 +58,8 @@
 #  include <malloc.h>
 #endif
 
+static const size_t linebuffer_size = 4096;
+
 static int _get_env_vars(struct cmd_context *cmd)
 {
 	const char *e;
@@ -1148,7 +1150,8 @@
 
 /* Entry point */
 struct cmd_context *create_toolcontext(unsigned is_long_lived,
-				       const char *system_dir)
+				       const char *system_dir,
+				       unsigned set_buffering)
 {
 	struct cmd_context *cmd;
 
@@ -1183,6 +1186,22 @@
 	/* FIXME Make this configurable? */
 	reset_lvm_errno(1);
 
+	/* Set in/out stream buffering before glibc */
+	if (set_buffering) {
+		/* Allocate 2 buffers */
+		if (!(cmd->linebuffer = dm_malloc(2 * linebuffer_size))) {
+			log_error("Failed to allocate line buffer.");
+			goto out;
+		}
+		if ((setvbuf(stdin, cmd->linebuffer, _IOLBF, linebuffer_size) ||
+		     setvbuf(stdout, cmd->linebuffer + linebuffer_size,
+			     _IOLBF, linebuffer_size))) {
+			log_sys_error("setvbuf", "");
+			goto out;
+		}
+		/* Buffers are used for lines without '\n' */
+	}
+
 	/*
 	 * Environment variable LVM_SYSTEM_DIR overrides this below.
 	 */
@@ -1419,6 +1438,15 @@
 	_destroy_tag_configs(cmd);
 	if (cmd->libmem)
 		dm_pool_destroy(cmd->libmem);
+
+	if (cmd->linebuffer) {
+		/* Reset stream buffering to defaults */
+		setlinebuf(stdin);
+		fflush(stdout);
+		setlinebuf(stdout);
+		dm_free(cmd->linebuffer);
+	}
+
 	dm_free(cmd);
 
 	release_log_memory();
--- LVM2/lib/commands/toolcontext.h	2010/12/10 22:39:54	1.42
+++ LVM2/lib/commands/toolcontext.h	2011/05/07 13:50:12	1.43
@@ -66,6 +66,7 @@
 	const char *kernel_vsn;
 
 	unsigned rand_seed;
+	char *linebuffer;
 	const char *cmd_line;
 	struct command *command;
 	char **argv;
@@ -109,7 +110,8 @@
  * The environment variable LVM_SYSTEM_DIR always takes precedence.
  */
 struct cmd_context *create_toolcontext(unsigned is_long_lived,
-				       const char *system_dir);
+				       const char *system_dir,
+				       unsigned set_buffering);
 void destroy_toolcontext(struct cmd_context *cmd);
 int refresh_toolcontext(struct cmd_context *cmd);
 int refresh_filters(struct cmd_context *cmd);
--- LVM2/daemons/clvmd/lvm-functions.c	2011/03/29 20:30:06	1.115
+++ LVM2/daemons/clvmd/lvm-functions.c	2011/05/07 13:50:13	1.116
@@ -919,7 +919,7 @@
 	init_syslog(LOG_DAEMON);
 	openlog("clvmd", LOG_PID, LOG_DAEMON);
 
-	if (!(cmd = create_toolcontext(1, NULL))) {
+	if (!(cmd = create_toolcontext(1, NULL, 0))) {
 		log_error("Failed to allocate command context");
 		return 0;
 	}

LVM2 tools/lvmcmdline.c liblvm/lvm_base.c lib/ ...

[Alasdair G Kergon]

On Sat, May 07, 2011 at 01:50:19PM -0000, mornfall at sourceware.org wrote:
> +	/* Set in/out stream buffering before glibc */

Please add more explanatory comments inline.

I mentioned this on IRC but there's been a trend towards not giving
explanations inline which I'd like to see reversed.  Patch headers
are becoming too long, containing information about the new version
of the code which should instead have been placed inline.

Alasdair

LVM2 tools/lvmcmdline.c liblvm/lvm_base.c lib/ ...

[Petr Rockai]

Hi,

Alasdair G Kergon <agk@redhat.com> writes:
> On Sat, May 07, 2011 at 01:50:19PM -0000, mornfall at sourceware.org wrote:
>> +	/* Set in/out stream buffering before glibc */
>
> Please add more explanatory comments inline.
>
> I mentioned this on IRC but there's been a trend towards not giving
> explanations inline which I'd like to see reversed.  Patch headers
> are becoming too long, containing information about the new version
> of the code which should instead have been placed inline.

I'd delegate this,

>> +  Avoid memlock size mismatch by preallocating stdio line buffers.

> If it fixed this, can't the temporary warning message suppression be
> removed now?

and this to Zden?k, since he's the author of the patch in question and
might therefore be better qualified to answer. Zden?k, if you'd prefer
to not deal with those, just bounce it back to me.

Yours,
   Petr

-- 
id' Ash = Ash; id' Dust = Dust; id' _ = undefined