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>

diff --git a/daemons/clvmd/lvm-functions.c b/daemons/clvmd/lvm-functions.c
index 166cd7f13649c35d0e5eecdd423f19f0f0d28861..8e68ed983bb7610eb16d54f17a3aede6fae45213 100644 (file)
--- a/daemons/clvmd/lvm-functions.c
+++ b/daemons/clvmd/lvm-functions.c
@@ -919,7 +919,7 @@ int init_clvm(int using_gulm, char **argv)
        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;
        }

diff --git a/lib/commands/toolcontext.c b/lib/commands/toolcontext.c
index 9b3e27f4e7ebf944f7620731765c4b002456dbe1..918362cef692106e98d592357ab478cf38e24d95 100644 (file)
--- a/lib/commands/toolcontext.c
+++ b/lib/commands/toolcontext.c
@@ -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 @@ static void _init_globals(struct cmd_context *cmd)
 
 /* 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 @@ struct cmd_context *create_toolcontext(unsigned is_long_lived,
        /* 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 @@ void destroy_toolcontext(struct cmd_context *cmd)
        _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();

diff --git a/lib/commands/toolcontext.h b/lib/commands/toolcontext.h
index 4628c7c2563935ccc007c2b805f4ab5a5a12afb8..1c3368e6949ebb2639704d2d1be05b6c66cacd3d 100644 (file)
--- a/lib/commands/toolcontext.h
+++ b/lib/commands/toolcontext.h
@@ -66,6 +66,7 @@ struct cmd_context {
        const char *kernel_vsn;
 
        unsigned rand_seed;
+       char *linebuffer;
        const char *cmd_line;
        struct command *command;
        char **argv;
@@ -109,7 +110,8 @@ struct cmd_context {
  * 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);

diff --git a/liblvm/lvm_base.c b/liblvm/lvm_base.c
index 9e1a8ecd87241d81085f0428c2354cc26e694338..f44b786cb12834bed79e4addef182d29cd579bdb 100644 (file)
--- a/liblvm/lvm_base.c
+++ b/liblvm/lvm_base.c
@@ -34,7 +34,7 @@ lvm_t lvm_init(const char *system_dir)
        /* 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;
 

diff --git a/tools/lvmcmdline.c b/tools/lvmcmdline.c
index 197cd1431859d96409e0dfb9e3b6ceabed183d2f..3e13a27d65980b28a1a71d8ba687f98733871f58 100644 (file)
--- a/tools/lvmcmdline.c
+++ b/tools/lvmcmdline.c
@@ -1282,7 +1282,7 @@ struct cmd_context *init_lvm(void)
        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];