User may specify a series of bio->bi_rw flags that must be seen in order
to trigger corruption (e.g. 33 = REQ_WRITE|REQ_META).

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
drivers/md/dm-flakey.c | 35 ++++++++++++++++++++++-------------
1 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index 54ab455..0205b00 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -28,7 +28,7 @@ struct flakey_c {
unsigned down_interval;
unsigned long flags;
unsigned corrupt_bio_byte;
- unsigned corrupt_bio_data_dir;
+ unsigned corrupt_bio_flags;
};

enum feature_flag_bits {
@@ -45,7 +45,7 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
static struct dm_arg _args[] = {
{0, 4, "invalid number of feature args"},
{1, UINT_MAX, "invalid corrupt bio byte value"},
- {0, 1, "invalid corrupt bio data direction"},
+ {0, UINT_MAX, "invalid corrupt bio flags mask"},
};

r = dm_read_arg(_args, dm_shift_arg(as), &argc, &ti->error);
@@ -59,19 +59,19 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
arg_name = dm_shift_arg(as);
argc--;

- /* corrupt_bio_byte <Nth byte> <READ=0|WRITE=1> */
- /* snitm: could also allow user to only corrupt bios that
- * have specific bi_rw flag(s), e.g.: (REQ_WRITE|REQ_META)?
- */
+ /* corrupt_bio_byte <Nth byte> <bio_flags> */
if (!strnicmp(arg_name, MESG_STR("corrupt_bio_byte")) &&
(argc >= 1)) {
r = dm_read_arg(_args + 1, dm_shift_arg(as),
&fc->corrupt_bio_byte, &ti->error);
argc--;

- /* corrupt reads or writes? */
+ /*
+ * Only corrupt bios that have specific bi_rw flag(s),
+ * e.g.: READ=0 or REQ_WRITE=1|REQ_META=32
+ */
r = dm_read_arg(_args + 2, dm_shift_arg(as),
- &fc->corrupt_bio_data_dir, &ti->error);
+ &fc->corrupt_bio_flags, &ti->error);
argc--;
continue;
}
@@ -193,14 +193,20 @@ static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
}

+#define corrupt_bio_data_dir(fc) ((fc)->corrupt_bio_flags & 1)
+#define all_corrupt_bio_flags_match(fc, bio)
+ (((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
+
static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
{
unsigned bio_bytes = bio_cur_bytes(bio);
char *data = bio_data(bio);

/* write 0 to the specified Nth byte of the bio */
- if (data && bio_bytes >= fc->corrupt_bio_byte)
+ if (data && bio_bytes >= fc->corrupt_bio_byte) {
data[fc->corrupt_bio_byte-1] = 0;
+ printk("corrupting data rw=%lu
", bio_data_dir(bio));
+ }
}

static int flakey_map(struct dm_target *ti, struct bio *bio,
@@ -214,9 +220,11 @@ static int flakey_map(struct dm_target *ti, struct bio *bio,
if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
unsigned rw = bio_data_dir(bio);
if (fc->corrupt_bio_byte) {
- /* only corrupt either reads or writes */
- if (rw == WRITE && rw == fc->corrupt_bio_data_dir)
+ /* corrupt matching writes, defer reads until end_io */
+ if (rw == WRITE && rw == corrupt_bio_data_dir(fc) &&
+ all_corrupt_bio_flags_match(fc, bio))
corrupt_bio_data(bio, fc);
+
/* flag this bio as submitted while down */
map_context->ll = 1;
goto map_bio;
@@ -247,7 +255,8 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio,
unsigned rw = bio_data_dir(bio);

if (!error && bio_submitted_while_down)
- if (rw == READ && rw == fc->corrupt_bio_data_dir)
+ if (rw == READ && rw == corrupt_bio_data_dir(fc) &&
+ all_corrupt_bio_flags_match(fc, bio))
corrupt_bio_data(bio, fc);

return error;
@@ -276,7 +285,7 @@ static int flakey_status(struct dm_target *ti, status_type_t type,

if (fc->corrupt_bio_byte)
DMEMIT("corrupt_bio_byte %u %u ", fc->corrupt_bio_byte,
- fc->corrupt_bio_data_dir);
+ fc->corrupt_bio_flags);
if (drop_writes)
DMEMIT("drop_writes ");
break;
--
1.7.1

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