dm flakey: add drop_writes
Add 'drop_writes' option to drop writes silently while the
device is 'down'. Reads are not touched.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index dd963dc..e7c4c2a 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -25,16 +25,22 @@
sector_t start;
unsigned up_interval;
unsigned down_interval;
+ unsigned long flags;
};
-static int parse_features(struct dm_arg_set *as, struct dm_target *ti)
+enum feature_flag_bits {
+ DROP_WRITES
+};
+
+static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
+ struct dm_target *ti)
{
int r;
unsigned argc;
const char *arg_name;
static struct dm_arg _args[] = {
- {0, 0, "Invalid number of feature args"},
+ {0, 1, "Invalid number of feature args"},
};
/* No feature arguments supplied. */
@@ -49,6 +55,18 @@
arg_name = dm_shift_arg(as);
argc--;
+ /*
+ * drop_writes
+ */
+ if (!strcasecmp(arg_name, "drop_writes")) {
+ if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
+ ti->error = "Feature drop_writes duplicated";
+ return -EINVAL;
+ }
+
+ continue;
+ }
+
ti->error = "Unrecognised flakey feature requested";
r = -EINVAL;
}
@@ -59,6 +77,9 @@
/*
* Construct a flakey mapping:
* <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
+ *
+ * Feature args:
+ * [drop_writes]
*/
static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
@@ -81,7 +102,7 @@
return -EINVAL;
}
- fc = kmalloc(sizeof(*fc), GFP_KERNEL);
+ fc = kzalloc(sizeof(*fc), GFP_KERNEL);
if (!fc) {
ti->error = "Cannot allocate linear context";
return -ENOMEM;
@@ -114,7 +135,7 @@
goto bad;
}
- r = parse_features(&as, ti);
+ r = parse_features(&as, fc, ti);
if (r)
goto bad;
@@ -162,12 +183,31 @@
{
struct flakey_c *fc = ti->private;
unsigned elapsed;
+ unsigned rw;
/* Are we alive ? */
elapsed = (jiffies - fc->start_time) / HZ;
- if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval)
- return -EIO;
+ if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
+ rw = bio_data_dir(bio);
+ /*
+ * Drop writes. Map reads as normal.
+ */
+ if (test_bit(DROP_WRITES, &fc->flags)) {
+ if (rw == WRITE) {
+ bio_endio(bio, 0);
+ return DM_MAPIO_SUBMITTED;
+ }
+ goto map_bio;
+ }
+
+ /*
+ * Default setting errors all I/O.
+ */
+ return -EIO;
+ }
+
+map_bio:
flakey_map_bio(ti, bio);
return DM_MAPIO_REMAPPED;
@@ -176,7 +216,9 @@
static int flakey_status(struct dm_target *ti, status_type_t type,
char *result, unsigned int maxlen)
{
+ unsigned sz = 0;
struct flakey_c *fc = ti->private;
+ unsigned drop_writes;
switch (type) {
case STATUSTYPE_INFO:
@@ -184,9 +226,14 @@
break;
case STATUSTYPE_TABLE:
- snprintf(result, maxlen, "%s %llu %u %u", fc->dev->name,
- (unsigned long long)fc->start, fc->up_interval,
- fc->down_interval);
+ DMEMIT("%s %llu %u %u ", fc->dev->name,
+ (unsigned long long)fc->start, fc->up_interval,
+ fc->down_interval);
+
+ drop_writes = test_bit(DROP_WRITES, &fc->flags);
+ DMEMIT("%u ", drop_writes);
+ if (drop_writes)
+ DMEMIT("drop_writes ");
break;
}
return 0;