With that option it is possible to tell the kernel via the writable
module parameter 'rq_mode' that it should use the request function
mode (request-by-request) instead of the default make request
function mode (bio-by-bio). The advantage is that a scheduler can
be used and the block layer cares for statistics.
Signed-off-by: Sebastian Parschauer <sebastian.riemer@xxxxxxxxxxxxxxxx>
---
Assemble.c | 4 ++++
Create.c | 4 ++++
ReadMe.c | 3 +++
mdadm.c | 5 +++++
mdadm.h | 3 +++
util.c | 34 ++++++++++++++++++++++++++++++++++
6 files changed, 53 insertions(+)
diff --git a/Assemble.c b/Assemble.c
index a57d384..d35d218 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -1275,6 +1275,10 @@ int Assemble(struct supertype *st, char *mddev,
mddev ? mddev : "further assembly");
return 1;
}
+ if (set_rq_mode(c->use_requestfn) != 0) {
+ pr_err("Cannot set the request function mode - cannot assemble.\n");
+ return 1;
+ }
if (devlist == NULL)
devlist = conf_get_devs();
diff --git a/Create.c b/Create.c
index 330c5b4..dc576f1 100644
--- a/Create.c
+++ b/Create.c
@@ -138,6 +138,10 @@ int Create(struct supertype *st, char *mddev,
pr_err("This level does not support spare devices\n");
return 1;
}
+ if (set_rq_mode(c->use_requestfn) != 0) {
+ pr_err("Cannot set the request function mode.\n");
+ return 1;
+ }
if (subdevs == 1 && strcmp(devlist->devname, "missing") != 0) {
/* If given a single device, it might be a container, and we can
diff --git a/ReadMe.c b/ReadMe.c
index bd8c85e..ecb829f 100644
--- a/ReadMe.c
+++ b/ReadMe.c
@@ -150,6 +150,7 @@ struct option long_options[] = {
{"force", 0, 0, Force},
{"update", 1, 0, 'U'},
{"freeze-reshape", 0, 0, FreezeReshape},
+ {"use-requestfn", 0, 0, UseRequestFn},
/* Management */
{"add", 0, 0, Add},
@@ -372,6 +373,7 @@ char Help_create[] =
" --name= -N : Textual name for array - max 32 characters\n"
" --bitmap-chunk= : bitmap chunksize in Kilobytes.\n"
" --delay= -d : bitmap update delay in seconds.\n"
+" --use-requestfn : Tell the kernel to process requests instead of bios.\n"
"\n"
;
@@ -456,6 +458,7 @@ char Help_assemble[] =
" --update= -U : Update superblock: try '-A --update=?' for option list.\n"
" --no-degraded : Assemble but do not start degraded arrays.\n"
" --readonly -o : Mark the array as read-only. No resync will start.\n"
+" --use-requestfn : Tell the kernel to process requests instead of bios.\n"
;
char Help_manage[] =
diff --git a/mdadm.c b/mdadm.c
index be990b8..35ff339 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -652,6 +652,11 @@ int main(int argc, char *argv[])
case O(INCREMENTAL, FreezeReshape):
c.freeze_reshape = 1;
continue;
+ case O(CREATE, UseRequestFn):
+ case O(ASSEMBLE, UseRequestFn):
+ case O(INCREMENTAL, UseRequestFn):
+ c.use_requestfn = 1;
+ continue;
case O(CREATE,'u'): /* uuid of array */
case O(ASSEMBLE,'u'): /* uuid of array */
if (ident.uuid_set) {
diff --git a/mdadm.h b/mdadm.h
index c0726bf..bb9f043 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -343,6 +343,7 @@ enum special_options {
Dump,
Restore,
Action,
+ UseRequestFn,
};
enum prefix_standard {
@@ -417,6 +418,7 @@ struct context {
char *backup_file;
int invalid_backup;
char *action;
+ int use_requestfn;
};
struct shape {
@@ -1355,6 +1357,7 @@ extern int remove_disk(int mdfd, struct supertype *st,
struct mdinfo *sra, struct mdinfo *info);
extern int set_array_info(int mdfd, struct supertype *st, struct mdinfo *info);
unsigned long long min_recovery_start(struct mdinfo *array);
+extern int set_rq_mode(int use_requestfn);
extern char *human_size(long long bytes);
extern char *human_size_brief(long long bytes, int prefix);
diff --git a/util.c b/util.c
index 7937eb6..b9c6cc3 100644
--- a/util.c
+++ b/util.c
@@ -1968,3 +1968,37 @@ void reopen_mddev(int mdfd)
if (fd >= 0 && fd != mdfd)
dup2(fd, mdfd);
}
+
+/*
+ * 0: make request fn mode (bio-by-bio)
+ * 1: request fn mode (request-by-request)
+ */
+#define BIO_MODE "0\n"
+#define REQ_MODE "1\n"
+
+int set_rq_mode(int use_requestfn)
+{
+ int fd, rv = 0;
+ ssize_t size, wbytes;
+ char *mode;
+
+ fd = open("/sys/module/md_mod/parameters/rq_mode", O_WRONLY);
+ if (fd < 0) {
+ if (errno != ENOENT || use_requestfn)
+ rv = 1;
+ goto out;
+ }
+ if (use_requestfn) {
+ mode = REQ_MODE;
+ size = sizeof(REQ_MODE);
+ } else {
+ mode = BIO_MODE;
+ size = sizeof(BIO_MODE);
+ }
+ wbytes = write(fd, mode, size);
+ if (wbytes != size)
+ rv = 1;
+ close(fd);
+out:
+ return rv;
+}
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
