diff -ruN bcache-tools-1.0.8/69-bcache.rules bcache-tools-1.0.8.2/69-bcache.rules
--- bcache-tools-1.0.8/69-bcache.rules 2014-12-04 23:51:24.000000000 +0100
+++ bcache-tools-1.0.8.2/69-bcache.rules 2015-02-07 22:32:35.000000000 +0100
@@ -22,11 +22,14 @@
RUN+="bcache-register $tempnode"
LABEL="bcache_backing_end"
-# Cached devices: symlink
-DRIVER=="bcache", ENV{CACHED_UUID}=="?*", \
- SYMLINK+="bcache/by-uuid/$env{CACHED_UUID}"
-DRIVER=="bcache", ENV{CACHED_LABEL}=="?*", \
- SYMLINK+="bcache/by-label/$env{CACHED_LABEL}"
+# Handling of cached devices
+DRIVER!="bcache", GOTO="bcache_end"
+
+# Apply kernel cmdline parameters
+RUN+="bcache-params $kernel"
+# Symlink
+ENV{CACHED_UUID}=="?*", SYMLINK+="bcache/by-uuid/$env{CACHED_UUID}"
+ENV{CACHED_LABEL}=="?*", SYMLINK+="bcache/by-label/$env{CACHED_LABEL}"
LABEL="bcache_end"
diff -ruN bcache-tools-1.0.8/bcache-params.c bcache-tools-1.0.8.2/bcache-params.c
--- bcache-tools-1.0.8/bcache-params.c 1970-01-01 01:00:00.000000000 +0100
+++ bcache-tools-1.0.8.2/bcache-params.c 2015-02-07 22:32:35.000000000 +0100
@@ -0,0 +1,196 @@
+/*
+ * Author: Rolf Fokkens <rolf@rolffokkens.nl>
+ *
+ * GPLv2
+ *
+ * For experimenting (or production) it may be useful to set bcache
+ * parameters in an early stage during boot, for example to tune the
+ * boot performance when the root fs is on a bcache device. The best
+ * moment is right before the root fs is actually mounted, which means
+ * it may need to be done in the initramfs.
+ *
+ * The bcache kernel driver does not support passing kernel cmdline
+ * arguments to it. This udev helper can be excuted from udev rules to
+ * take care of cmdline arguments by changing bcache parameters using
+ * the /sys interface right after a bcache device is brought up. This
+ * works both in the initramfs and later.
+ *
+ * It recognizes cmdline arguments like these:
+ * bcache=sco:0,crdthr:0,cache/congested_write_threshold_us:0
+ * This means:
+ * - for any bcache device set the following parameters:
+ * - sequential_cutoff (sco) is set to 0
+ * - cache/congested_read_threshold_us (crdthr) is set to 0
+ * - cache/congested_write_threshold_us (cwrthr) is set to 0
+ * Both short aliases (for user convenience) and full parameters can be used,
+ * they are defined in the parm_map below.
+ *
+ * Other parameters are not accepted, because they're not useful or
+ * potentially harmful (e.g. changing the label, stopping bcache devices)
+ *
+ * Parsing of each kernel cmdline argument is done in a simple way:
+ * - does the argument start with "bcache="? If not: next argument.
+ * - for the rest of the argument, identify "subarguments":
+ * - is what follows of the form <stringP>:<stringV>? If not: next argument
+ * - is <stringP> a know parameter name? If not: next subargument
+ * - process the subargument
+ * - next subargument
+ */
+
+#include <ctype.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <error.h>
+#include <errno.h>
+
+#ifndef TESTING
+# define CMDLINE "/proc/cmdline"
+# define SYSPFX "/sys/block"
+#else
+# define CMDLINE "/tmp/cmdline"
+# define SYSPFX "/tmp"
+#endif
+
+struct parm_map {
+ char *id;
+ char *full;
+};
+
+/*
+ * The list of kernel cmdline patameters that can be processed by
+ * bcache-patams.
+ */
+struct parm_map parm_map[] = {
+ { "crdthr", "cache/congested_read_threshold_us" }
+, { "cwrthr", "cache/congested_write_threshold_us" }
+, { "rdahed", "readahead" }
+, { "sctoff", "sequential_cutoff" }
+, { "wrbdly", "writeback_delay" }
+, { "wrbpct", "writeback_percent" }
+, { "wrbupd", "writeback_rate_update_seconds" }
+, { NULL , NULL }
+};
+
+/*
+ * Read characters from fp (/proc/cmdline) into buf until maxlen characters are
+ * read or until a character is read that is in the list of terminators.
+ *
+ * lookaheadp points to the current lookahead symbol, and is returned as such to
+ * the caller.
+ *
+ * When a characters is read that is a terminator charachter, the lookehead is moved
+ * one character ahead and the encountered terminator is returned.
+ *
+ * If for another reason reading characters stops, 0 is returned.
+ */
+int read_until (int *lookaheadp, FILE *fp, char *buf, int maxlen, char *terminators)
+{
+ char *cp = buf, *ep = buf + maxlen;
+ int lookahead = *lookaheadp;
+
+ while ( cp < ep
+ && lookahead != EOF
+ && isprint (lookahead)
+ && !strchr (terminators, lookahead)) {
+ *cp++ = lookahead;
+ lookahead = fgetc (fp);
+ }
+
+ *lookaheadp = lookahead;
+
+ *cp = '\0';
+
+ if (strchr (terminators, lookahead)) {
+ *lookaheadp = fgetc (fp);
+ return lookahead;
+ }
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ char buf[256];
+ int la, bufsz = sizeof (buf);
+ FILE *fp;
+
+ if (argc != 2) {
+ fprintf (stderr, "bcache-params takes exactly one argument\n");
+ return 1;
+ }
+
+ fp = fopen (CMDLINE, "r");
+ if (fp == NULL) {
+ perror ("Error opening /proc/cmdline");
+ return 1;
+ }
+ /* la is our lookahead character */
+ la = fgetc (fp);
+
+ while (la != EOF) {
+ /* skip any spaces */
+ while (la == ' ') {
+ la = fgetc (fp);
+ }
+ /* stop ehen end of the line */
+ if (la == EOF) break;
+
+ /* process until '=' */
+ if (read_until (&la, fp, buf, bufsz, " =") != '=') goto nextarg;
+ /* did we get a "bcache=" prefix? */
+ if (strcmp (buf, "bcache") != 0) goto nextarg;
+
+ /* process subarguments */
+ for (;;) {
+ struct parm_map *pmp;
+ char sysfile[256];
+ int term, fd;
+
+ /* all subargs start with "<string>:" */
+ if (read_until (&la, fp, buf, bufsz, " :") != ':') goto nextarg;
+
+ /* now identify <string> */
+ for (pmp = parm_map; pmp->id != NULL; pmp++) {
+ if (strcmp (buf, pmp->id) == 0) break;
+ if (strcmp (buf, pmp->full) == 0) break;
+ }
+ /* no match for <string>? next subargument */
+ if (pmp->id == NULL) {
+ error (0, 0, "Unknown bcache parameter %s", buf);
+ } else {
+ /* Now we know what /sys file to write to */
+ sprintf (sysfile, "%s/%s/bcache/%s", SYSPFX, argv[1], pmp->full);
+ }
+
+ /* What follows is the data to be written */
+ term = read_until (&la, fp, buf, bufsz, " ,");
+
+ if (pmp->id == NULL) goto nextsubarg;
+
+ /* no data identified? next subargument */
+ if (buf[0] == '\0') {
+ error (0, 0, "Missing data for parameter %s(%s)", pmp->full, pmp->id);
+ goto nextsubarg;
+ }
+ /* we're ready to actually write the data */
+ fd = open (sysfile, O_WRONLY);
+ if (fd < 0) {
+ error (0, errno, "Error opening %s", sysfile);
+ goto nextsubarg;
+ }
+ if (dprintf (fd, "%s\n", buf) < 0) {
+ error (0, errno, "Error writing %s to %s", buf, sysfile);
+ }
+ close (fd);
+ /* From here there's the hope for another subargument */
+ nextsubarg:
+ if (term != ',') break;
+ }
+ nextarg:
+ while (la != EOF && la != ' ') la = fgetc (fp);
+ }
+ return 0;
+}
+
diff -ruN bcache-tools-1.0.8/dracut/module-setup.sh bcache-tools-1.0.8.2/dracut/module-setup.sh
--- bcache-tools-1.0.8/dracut/module-setup.sh 2014-12-04 23:51:24.000000000 +0100
+++ bcache-tools-1.0.8.2/dracut/module-setup.sh 2015-02-07 22:32:35.000000000 +0100
@@ -29,6 +29,9 @@
}
install() {
- inst_multiple ${udevdir}/probe-bcache ${udevdir}/bcache-register
+ inst_multiple \
+ ${udevdir}/probe-bcache \
+ ${udevdir}/bcache-register \
+ ${udevdir}/bcache-params
inst_rules 69-bcache.rules
}
diff -ruN bcache-tools-1.0.8/.gitignore bcache-tools-1.0.8.2/.gitignore
--- bcache-tools-1.0.8/.gitignore 2014-12-04 23:51:24.000000000 +0100
+++ bcache-tools-1.0.8.2/.gitignore 2015-02-07 22:32:35.000000000 +0100
@@ -1,6 +1,7 @@
/bcache-super-show
/bcache-test
/bcache-register
+/bcache-params
/make-bcache
/probe-bcache
.*
diff -ruN bcache-tools-1.0.8/Makefile bcache-tools-1.0.8.2/Makefile
--- bcache-tools-1.0.8/Makefile 2014-12-04 23:51:24.000000000 +0100
+++ bcache-tools-1.0.8.2/Makefile 2015-02-07 22:32:35.000000000 +0100
@@ -5,11 +5,11 @@
INSTALL=install
CFLAGS+=-O2 -Wall -g
-all: make-bcache probe-bcache bcache-super-show bcache-register
+all: make-bcache probe-bcache bcache-super-show bcache-register bcache-params
-install: make-bcache probe-bcache bcache-super-show
+install: make-bcache probe-bcache bcache-super-show bcache-register bcache-params
$(INSTALL) -m0755 make-bcache bcache-super-show $(DESTDIR)${PREFIX}/sbin/
- $(INSTALL) -m0755 probe-bcache bcache-register $(DESTDIR)$(UDEVLIBDIR)/
+ $(INSTALL) -m0755 probe-bcache bcache-register bcache-params $(DESTDIR)$(UDEVLIBDIR)/
$(INSTALL) -m0644 69-bcache.rules $(DESTDIR)$(UDEVLIBDIR)/rules.d/
$(INSTALL) -m0644 -- *.8 $(DESTDIR)${PREFIX}/share/man/man8/
$(INSTALL) -D -m0755 initramfs/hook $(DESTDIR)/usr/share/initramfs-tools/hooks/bcache
@@ -30,3 +30,4 @@
bcache-super-show: CFLAGS += -std=gnu99
bcache-super-show: bcache.o
bcache-register: bcache-register.o
+bcache-params: bcache-params.o