Attached are a series of three patches affecting swaponoff.
Patch #1 fixes two small logic errors: (a) the bb_strtou function was called
inside an instantiation of the MIN macro, which would cause the function to be
called twice in the common case; and (b) the actual maximum allowable swap
priority is SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT, not simply
SWAP_FLAG_PRIO_MASK as the code previously assumed. It just so happens that
SWAP_FLAG_PRIO_SHIFT == 0, but one should not rely on that serendipity.
Patch #2 fixes the interaction of the -a and -p options to swapon. When -p is
given on the command line, the specified priority should be applied to any swap
areas given in /etc/fstab that lack a 'pri' option. This is the way swapon from
util-linux does it, and it's the rational behavior, or else -p and -a should be
mutually exclusive options.
Patch #3 adds a -d option to swapon, which sets SWAP_FLAG_DISCARD and
potentially SWAP_FLAG_DISCARD_ONCE or SWAP_FLAG_DISCARD_PAGES if a policy is
given. The patch also adds support for the 'discard' option in swap entries in
/etc/fstab.
>From 1509caf8e5088ed92ae6c7ab54d65785df570351 Mon Sep 17 00:00:00 2001
From: Matt Whitlock <busy...@mattwhitlock.name>
Date: Sat, 22 Mar 2014 18:54:24 -0400
Subject: [PATCH 1/3] avoid calling bb_strtou twice in MIN macro expansion
Also, the maximum allowable value of swap priority is technically SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT.
---
util-linux/swaponoff.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/util-linux/swaponoff.c b/util-linux/swaponoff.c
index 3f22334..d35e30e 100644
--- a/util-linux/swaponoff.c
+++ b/util-linux/swaponoff.c
@@ -100,12 +100,12 @@ static int do_em_all(void)
g_flags = 0; /* each swap space might have different flags */
p = hasmntopt(m, "pri");
if (p) {
- /* Max allowed 32767 (==SWAP_FLAG_PRIO_MASK) */
- unsigned int swap_prio = MIN(bb_strtou(p + 4 , NULL, 10), SWAP_FLAG_PRIO_MASK);
+ /* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT) */
+ unsigned prio = bb_strtou(p + 4, NULL, 10);
/* We want to allow "NNNN,foo", thus errno == EINVAL is allowed too */
if (errno != ERANGE) {
g_flags = SWAP_FLAG_PREFER |
- (swap_prio << SWAP_FLAG_PRIO_SHIFT);
+ MIN(prio, SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT) << SWAP_FLAG_PRIO_SHIFT;
}
}
#endif
@@ -124,6 +124,9 @@ int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
{
int ret;
+#if ENABLE_FEATURE_SWAPON_PRI
+ unsigned prio;
+#endif
INIT_G();
@@ -132,11 +135,11 @@ int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
#else
if (applet_name[5] == 'n')
opt_complementary = "p+";
- ret = getopt32(argv, (applet_name[5] == 'n') ? "ap:" : "a", &g_flags);
+ ret = getopt32(argv, (applet_name[5] == 'n') ? "ap:" : "a", &prio);
if (ret & 2) { // -p
g_flags = SWAP_FLAG_PREFER |
- ((g_flags & SWAP_FLAG_PRIO_MASK) << SWAP_FLAG_PRIO_SHIFT);
+ MIN(prio, SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT) << SWAP_FLAG_PRIO_SHIFT;
ret &= 1;
}
#endif
--
1.9.1
>From e7d0d02ca14aea0e12c2ca6b84e124db25172209 Mon Sep 17 00:00:00 2001
From: Matt Whitlock <busy...@mattwhitlock.name>
Date: Sat, 22 Mar 2014 19:10:08 -0400
Subject: [PATCH 2/3] fix interaction of -a and -p options in swapon
Swap entries in /etc/fstab inherit the priority specified on the command line unless they have 'pri' in their mount options.
---
util-linux/swaponoff.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/util-linux/swaponoff.c b/util-linux/swaponoff.c
index d35e30e..df0c524 100644
--- a/util-linux/swaponoff.c
+++ b/util-linux/swaponoff.c
@@ -82,6 +82,9 @@ static int do_em_all(void)
struct mntent *m;
FILE *f;
int err;
+#ifdef G
+ int cl_flags = g_flags;
+#endif
f = setmntent("/etc/fstab", "r");
if (f == NULL)
@@ -97,14 +100,14 @@ static int do_em_all(void)
) {
#if ENABLE_FEATURE_SWAPON_PRI
char *p;
- g_flags = 0; /* each swap space might have different flags */
+ g_flags = cl_flags; /* each swap space might have different flags */
p = hasmntopt(m, "pri");
if (p) {
/* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT) */
unsigned prio = bb_strtou(p + 4, NULL, 10);
/* We want to allow "NNNN,foo", thus errno == EINVAL is allowed too */
if (errno != ERANGE) {
- g_flags = SWAP_FLAG_PREFER |
+ g_flags = (g_flags & ~SWAP_FLAG_PRIO_MASK) | SWAP_FLAG_PREFER |
MIN(prio, SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT) << SWAP_FLAG_PRIO_SHIFT;
}
}
--
1.9.1
>From b2b2e65829785c959881d643bcff8843a6cddf7e Mon Sep 17 00:00:00 2001
From: Matt Whitlock <busy...@mattwhitlock.name>
Date: Sat, 22 Mar 2014 19:21:01 -0400
Subject: [PATCH 3/3] add discard option -d to swapon
---
util-linux/Config.src | 9 ++++++
util-linux/swaponoff.c | 85 ++++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 85 insertions(+), 9 deletions(-)
diff --git a/util-linux/Config.src b/util-linux/Config.src
index 5a8b006..c1cd6da 100644
--- a/util-linux/Config.src
+++ b/util-linux/Config.src
@@ -599,6 +599,15 @@ config SWAPONOFF
space. If you are not using any swap space, you can leave this
option disabled.
+config FEATURE_SWAPON_DISCARD
+ bool "Support discard option -d"
+ default y
+ depends on SWAPONOFF
+ help
+ Enable support for discarding swap area blocks at swapon and/or as
+ the kernel frees them. This option enables both the -d option on
+ 'swapon' and the 'discard' option for swap entries in /etc/fstab.
+
config FEATURE_SWAPON_PRI
bool "Support priority option -p"
default y
diff --git a/util-linux/swaponoff.c b/util-linux/swaponoff.c
index df0c524..0080ea7c 100644
--- a/util-linux/swaponoff.c
+++ b/util-linux/swaponoff.c
@@ -8,10 +8,14 @@
*/
//usage:#define swapon_trivial_usage
-//usage: "[-a]" IF_FEATURE_SWAPON_PRI(" [-p PRI]") " [DEVICE]"
+//usage: "[-a]" IF_FEATURE_SWAPON_DISCARD(" [-d[POL]]") IF_FEATURE_SWAPON_PRI(" [-p PRI]") " [DEVICE]"
//usage:#define swapon_full_usage "\n\n"
//usage: "Start swapping on DEVICE\n"
//usage: "\n -a Start swapping on all swap devices"
+//usage: IF_FEATURE_SWAPON_DISCARD(
+//usage: "\n -d[POL] Discard blocks at swapon (POL=once),"
+//usage: "\n as freed (POL=pages), or both (POL omitted)"
+//usage: )
//usage: IF_FEATURE_SWAPON_PRI(
//usage: "\n -p PRI Set swap device priority"
//usage: )
@@ -38,7 +42,22 @@
# define MNTTYPE_SWAP "swap"
#endif
-#if ENABLE_FEATURE_SWAPON_PRI
+#if ENABLE_FEATURE_SWAPON_DISCARD
+#ifndef SWAP_FLAG_DISCARD
+#define SWAP_FLAG_DISCARD 0x10000
+#endif
+#ifndef SWAP_FLAG_DISCARD_ONCE
+#define SWAP_FLAG_DISCARD_ONCE 0x20000
+#endif
+#ifndef SWAP_FLAG_DISCARD_PAGES
+#define SWAP_FLAG_DISCARD_PAGES 0x40000
+#endif
+#define SWAP_FLAG_DISCARD_MASK \
+ (SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | SWAP_FLAG_DISCARD_PAGES)
+#endif
+
+
+#if ENABLE_FEATURE_SWAPON_DISCARD || ENABLE_FEATURE_SWAPON_PRI
struct globals {
int flags;
} FIX_ALIASING;
@@ -98,9 +117,23 @@ static int do_em_all(void)
if (applet_name[5] != 'n'
|| hasmntopt(m, MNTOPT_NOAUTO) == NULL
) {
-#if ENABLE_FEATURE_SWAPON_PRI
+#if ENABLE_FEATURE_SWAPON_DISCARD || ENABLE_FEATURE_SWAPON_PRI
char *p;
g_flags = cl_flags; /* each swap space might have different flags */
+#if ENABLE_FEATURE_SWAPON_DISCARD
+ p = hasmntopt(m, "discard");
+ if (p) {
+ if (p[7] == '=') {
+ if (strncmp(p + 8, "once", 4) == 0 && (p[12] == ',' || p[12] == '\0'))
+ g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE;
+ else if (strncmp(p + 8, "pages", 5) == 0 && (p[13] == ',' || p[13] == '\0'))
+ g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_PAGES;
+ }
+ else if (p[7] == ',' || p[7] == '\0')
+ g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD;
+ }
+#endif
+#if ENABLE_FEATURE_SWAPON_PRI
p = hasmntopt(m, "pri");
if (p) {
/* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT) */
@@ -112,6 +145,7 @@ static int do_em_all(void)
}
}
#endif
+#endif
err += swap_enable_disable(m->mnt_fsname);
}
}
@@ -127,24 +161,57 @@ int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
{
int ret;
+#if ENABLE_FEATURE_SWAPON_DISCARD
+ char *discard = NULL;
+#endif
#if ENABLE_FEATURE_SWAPON_PRI
unsigned prio;
#endif
INIT_G();
-#if !ENABLE_FEATURE_SWAPON_PRI
+#if !ENABLE_FEATURE_SWAPON_DISCARD && !ENABLE_FEATURE_SWAPON_PRI
ret = getopt32(argv, "a");
#else
+#if ENABLE_FEATURE_SWAPON_PRI
if (applet_name[5] == 'n')
opt_complementary = "p+";
- ret = getopt32(argv, (applet_name[5] == 'n') ? "ap:" : "a", &prio);
+#endif
+ ret = getopt32(argv, (applet_name[5] == 'n') ?
+#if ENABLE_FEATURE_SWAPON_DISCARD
+ "d::"
+#endif
+#if ENABLE_FEATURE_SWAPON_PRI
+ "p:"
+#endif
+ "a" : "a"
+#if ENABLE_FEATURE_SWAPON_DISCARD
+ , &discard
+#endif
+#if ENABLE_FEATURE_SWAPON_PRI
+ , &prio
+#endif
+ );
+#endif
- if (ret & 2) { // -p
- g_flags = SWAP_FLAG_PREFER |
- MIN(prio, SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT) << SWAP_FLAG_PRIO_SHIFT;
- ret &= 1;
+#if ENABLE_FEATURE_SWAPON_DISCARD
+ if (ret & 1) { // -d
+ if (!discard)
+ g_flags |= SWAP_FLAG_DISCARD;
+ else if (strcmp(discard, "once") == 0)
+ g_flags |= SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE;
+ else if (strcmp(discard, "pages") == 0)
+ g_flags |= SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_PAGES;
+ else
+ bb_show_usage();
}
+ ret >>= 1;
+#endif
+#if ENABLE_FEATURE_SWAPON_PRI
+ if (ret & 1) // -p
+ g_flags |= SWAP_FLAG_PREFER |
+ MIN(prio, SWAP_FLAG_PRIO_MASK >> SWAP_FLAG_PRIO_SHIFT) << SWAP_FLAG_PRIO_SHIFT;
+ ret >>= 1;
#endif
if (ret /* & 1: not needed */) // -a
--
1.9.1
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