Commit aa7d7bc9 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm flakey: add an "error_reads" option 



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: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent e3675dc1

Documentation/admin-guide/device-mapper/dm-flakey.rst

+4 −0
Original line number Diff line number Diff line
@@ -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.

drivers/md/dm-flakey.c

+27 −12
Original line number Diff line number Diff line
@@ -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)