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dm flakey: add an "error_reads" option

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dm-flakey returns error on reads if no other argument is specified.
This commit simplifies associated logic while formalizing an
"error_reads" argument and an ERROR_READS flag.

If no argument is specified, set ERROR_READS flag so that it behaves
just like before this commit.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mikulas Patocka 2023-04-18 15:56:41 -04:00 committed by Mike Snitzer
parent e3675dc1e7
commit aa7d7bc99f
2 changed files with 31 additions and 12 deletions
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4
Documentation/admin-guide/device-mapper/dm-flakey.rst
View file

@ -39,6 +39,10 @@ Optional feature parameters:
If no feature parameters are present, during the periods of
unreliability, all I/O returns errors.
error_reads:
All read I/O is failed with an error signalled.
Write I/O is handled correctly.
drop_writes:
All write I/O is silently ignored.
Read I/O is handled correctly.

39
drivers/md/dm-flakey.c
View file

@ -37,6 +37,7 @@ struct flakey_c {
};
enum feature_flag_bits {
ERROR_READS,
DROP_WRITES,
ERROR_WRITES
};
@ -53,7 +54,7 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
const char *arg_name;
static const struct dm_arg _args[] = {
{0, 6, "Invalid number of feature args"},
{0, 7, "Invalid number of feature args"},
{1, UINT_MAX, "Invalid corrupt bio byte"},
{0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
{0, UINT_MAX, "Invalid corrupt bio flags mask"},
@ -76,6 +77,17 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
return -EINVAL;
}
/*
* error_reads
*/
if (!strcasecmp(arg_name, "error_reads")) {
if (test_and_set_bit(ERROR_READS, &fc->flags)) {
ti->error = "Feature error_reads duplicated";
return -EINVAL;
}
continue;
}
/*
* drop_writes
*/
@ -171,6 +183,12 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
return -EINVAL;
}
if (!fc->corrupt_bio_byte && !test_bit(ERROR_READS, &fc->flags) &&
!test_bit(DROP_WRITES, &fc->flags) && !test_bit(ERROR_WRITES, &fc->flags)) {
set_bit(ERROR_WRITES, &fc->flags);
set_bit(ERROR_READS, &fc->flags);
}
return 0;
}
@ -346,8 +364,7 @@ static int flakey_map(struct dm_target *ti, struct bio *bio)
* Otherwise, flakey_end_io() will decide if the reads should be modified.
*/
if (bio_data_dir(bio) == READ) {
if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
!test_bit(ERROR_WRITES, &fc->flags))
if (test_bit(ERROR_READS, &fc->flags))
return DM_MAPIO_KILL;
goto map_bio;
}
@ -373,11 +390,6 @@ static int flakey_map(struct dm_target *ti, struct bio *bio)
}
goto map_bio;
}
/*
* By default, error all I/O.
*/
return DM_MAPIO_KILL;
}
map_bio:
@ -404,8 +416,8 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio,
*/
corrupt_bio_data(bio, fc);
}
} else if (!test_bit(DROP_WRITES, &fc->flags) &&
!test_bit(ERROR_WRITES, &fc->flags)) {
}
if (test_bit(ERROR_READS, &fc->flags)) {
/*
* Error read during the down_interval if drop_writes
* and error_writes were not configured.
@ -422,7 +434,7 @@ static void flakey_status(struct dm_target *ti, status_type_t type,
{
unsigned int sz = 0;
struct flakey_c *fc = ti->private;
unsigned int drop_writes, error_writes;
unsigned int error_reads, drop_writes, error_writes;
switch (type) {
case STATUSTYPE_INFO:
@ -434,10 +446,13 @@ static void flakey_status(struct dm_target *ti, status_type_t type,
(unsigned long long)fc->start, fc->up_interval,
fc->down_interval);
error_reads = test_bit(ERROR_READS, &fc->flags);
drop_writes = test_bit(DROP_WRITES, &fc->flags);
error_writes = test_bit(ERROR_WRITES, &fc->flags);
DMEMIT(" %u", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
DMEMIT(" %u", error_reads + drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
if (error_reads)
DMEMIT(" error_reads");
if (drop_writes)
DMEMIT(" drop_writes");
else if (error_writes)