FAQ Search Today's Posts Mark Forums Read
» Video Reviews

» Linux Archive

Linux-archive is a website aiming to archive linux email lists and to make them easily accessible for linux users/developers.


» Sponsor

» Partners

» Sponsor

Go Back   Linux Archive > Redhat > Device-mapper Development

 
 
LinkBack Thread Tools
 
Old 06-27-2011, 07:53 PM
Mike Snitzer
 
Default dm flakey: add drop_writes feature

Add 'drop_writes' feature that will silently drop writes (when the
device is "down"). Reads are not touched.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
drivers/md/dm-flakey.c | 47 +++++++++++++++++++++++++++++++++++++++--------
1 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index ae2107f..618f313 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>

#define DM_MSG_PREFIX "flakey"
+#define MESG_STR(x) x, sizeof(x)

/*
* Flakey: Used for testing only, simulates intermittent,
@@ -25,16 +26,22 @@ struct flakey_c {
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"},
};

r = dm_read_arg(_args, dm_shift_arg(as), &argc, &ti->error);
@@ -48,6 +55,11 @@ static int parse_features(struct dm_arg_set *as, struct dm_target *ti)
arg_name = dm_shift_arg(as);
argc--;

+ if (!strnicmp(arg_name, MESG_STR("drop_writes"))) {
+ set_bit(DROP_WRITES, &fc->flags);
+ continue;
+ }
+
ti->error = "Unrecognised flakey feature request";
r = -EINVAL;
}
@@ -80,7 +92,7 @@ static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
return -EINVAL;
}

- fc = kmalloc(sizeof(*fc), GFP_KERNEL);
+ fc = kzalloc(sizeof(*fc), GFP_KERNEL);
if (!fc) {
ti->error = "dm-flakey: Cannot allocate linear context";
return -ENOMEM;
@@ -117,7 +129,7 @@ static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto bad;
}

- r = parse_features(&as, ti);
+ r = parse_features(&as, fc, ti);
if (r)
goto bad;

@@ -168,9 +180,21 @@ static int flakey_map(struct dm_target *ti, struct bio *bio,

/* Are we alive ? */
elapsed = (jiffies - fc->start_time) / HZ;
- if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval)
+ if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
+ unsigned rw = bio_data_dir(bio);
+ if (test_bit(DROP_WRITES, &fc->flags)) {
+ /* drop writes but don't error reads */
+ if (rw == WRITE) {
+ bio_endio(bio, 0);
+ return DM_MAPIO_SUBMITTED;
+ } else
+ goto map_bio;
+ }
+ /* default, when down without features, is to error all IO */
return -EIO;
+ }

+map_bio:
flakey_map_bio(ti, bio);

return DM_MAPIO_REMAPPED;
@@ -179,7 +203,9 @@ static int flakey_map(struct dm_target *ti, struct bio *bio,
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:
@@ -187,9 +213,14 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
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;
--
1.7.1

--
dm-devel mailing list
dm-devel@redhat.com
https://www.redhat.com/mailman/listinfo/dm-devel
 

Thread Tools




All times are GMT. The time now is 03:00 PM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.
Copyright 2007 - 2008, www.linux-archive.org