dm flakey: add corrupt_bio_byte feature (a3998799) · Commits · e / devices / android_kernel_samsung_universal8895

Documentation/device-mapper/dm-flakey.txt

+19 −0

Original line number	Original line	Diff line number	Diff line
	@@ -32,3 +32,22 @@ Optional feature parameters:
	drop_writes:		drop_writes:
	All write I/O is silently ignored.		All write I/O is silently ignored.
	Read I/O is handled correctly.		Read I/O is handled correctly.

			corrupt_bio_byte <Nth_byte> <direction> <value> <flags>:
			During <down interval>, replace <Nth_byte> of the data of
			each matching bio with <value>.

			<Nth_byte>: The offset of the byte to replace.
			Counting starts at 1, to replace the first byte.
			<direction>: Either 'r' to corrupt reads or 'w' to corrupt writes.
			'w' is incompatible with drop_writes.
			<value>: The value (from 0-255) to write.
			<flags>: Perform the replacement only if bio->bi_rw has all the
			selected flags set.

			Examples:
			corrupt_bio_byte 32 r 1 0
			- replaces the 32nd byte of READ bios with the value 1

			corrupt_bio_byte 224 w 0 32
			- replaces the 224th byte of REQ_META (=32) bios with the value 0

drivers/md/dm-flakey.c

+140 −15

Original line number	Original line	Diff line number	Diff line
	/*		/*
	* Copyright (C) 2003 Sistina Software (UK) Limited.		* Copyright (C) 2003 Sistina Software (UK) Limited.
	* Copyright (C) 2004, 2010 Red Hat, Inc. All rights reserved.		* Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
	*		*
	* This file is released under the GPL.		* This file is released under the GPL.
	*/		*/
	@@ -15,6 +15,9 @@

	#define DM_MSG_PREFIX "flakey"		#define DM_MSG_PREFIX "flakey"

			#define all_corrupt_bio_flags_match(bio, fc) \
			(((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)

	/*		/*
	* Flakey: Used for testing only, simulates intermittent,		* Flakey: Used for testing only, simulates intermittent,
	* catastrophic device failure.		* catastrophic device failure.
	@@ -26,6 +29,10 @@ struct flakey_c {
	unsigned up_interval;		unsigned up_interval;
	unsigned down_interval;		unsigned down_interval;
	unsigned long flags;		unsigned long flags;
			unsigned corrupt_bio_byte;
			unsigned corrupt_bio_rw;
			unsigned corrupt_bio_value;
			unsigned corrupt_bio_flags;
	};		};

	enum feature_flag_bits {		enum feature_flag_bits {
	@@ -40,7 +47,10 @@ static int parse_features(struct dm_arg_set as, struct flakey_c fc,
	const char *arg_name;		const char *arg_name;

	static struct dm_arg _args[] = {		static struct dm_arg _args[] = {
	{0, 1, "Invalid number of feature args"},		{0, 6, "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"},
	};		};

	/* No feature arguments supplied. */		/* No feature arguments supplied. */
	@@ -49,9 +59,9 @@ static int parse_features(struct dm_arg_set as, struct flakey_c fc,

	r = dm_read_arg_group(_args, as, &argc, &ti->error);		r = dm_read_arg_group(_args, as, &argc, &ti->error);
	if (r)		if (r)
	return -EINVAL;		return r;

	while (argc && !r) {		while (argc) {
	arg_name = dm_shift_arg(as);		arg_name = dm_shift_arg(as);
	argc--;		argc--;

	@@ -67,11 +77,61 @@ static int parse_features(struct dm_arg_set as, struct flakey_c fc,
	continue;		continue;
	}		}

	ti->error = "Unrecognised flakey feature requested";		/*
	r = -EINVAL;		* corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
			*/
			if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
			if (!argc)
			ti->error = "Feature corrupt_bio_byte requires parameters";

			r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
			if (r)
			return r;
			argc--;

			/*
			* Direction r or w?
			*/
			arg_name = dm_shift_arg(as);
			if (!strcasecmp(arg_name, "w"))
			fc->corrupt_bio_rw = WRITE;
			else if (!strcasecmp(arg_name, "r"))
			fc->corrupt_bio_rw = READ;
			else {
			ti->error = "Invalid corrupt bio direction (r or w)";
			return -EINVAL;
	}		}
			argc--;

			/*
			* Value of byte (0-255) to write in place of correct one.
			*/
			r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
			if (r)
			return r;
			argc--;

			/*
			* Only corrupt bios with these flags set.
			*/
			r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
			if (r)
	return r;		return r;
			argc--;

			continue;
			}

			ti->error = "Unrecognised flakey feature requested";
			return -EINVAL;
			}

			if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
			ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
			return -EINVAL;
			}

			return 0;
	}		}

	/*		/*
	@@ -80,6 +140,11 @@ static int parse_features(struct dm_arg_set as, struct flakey_c fc,
	*		*
	* Feature args:		* Feature args:
	* [drop_writes]		* [drop_writes]
			* [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
			*
			* Nth_byte starts from 1 for the first byte.
			* Direction is r for READ or w for WRITE.
			* bio_flags is ignored if 0.
	*/		*/
	static int flakey_ctr(struct dm_target ti, unsigned int argc, char *argv)		static int flakey_ctr(struct dm_target ti, unsigned int argc, char *argv)
	{		{
	@@ -178,31 +243,64 @@ static void flakey_map_bio(struct dm_target ti, struct bio bio)
	bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);		bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
	}		}

			static void corrupt_bio_data(struct bio bio, struct flakey_c fc)
			{
			unsigned bio_bytes = bio_cur_bytes(bio);
			char *data = bio_data(bio);

			/*
			* Overwrite the Nth byte of the data returned.
			*/
			if (data && bio_bytes >= fc->corrupt_bio_byte) {
			data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;

			DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
			"(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
			bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
			(bio_data_dir(bio) == WRITE) ? 'w' : 'r',
			bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
			}
			}

	static int flakey_map(struct dm_target ti, struct bio bio,		static int flakey_map(struct dm_target ti, struct bio bio,
	union map_info *map_context)		union map_info *map_context)
	{		{
	struct flakey_c *fc = ti->private;		struct flakey_c *fc = ti->private;
	unsigned elapsed;		unsigned elapsed;
	unsigned rw;

	/* Are we alive ? */		/* Are we alive ? */
	elapsed = (jiffies - fc->start_time) / HZ;		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) {
	rw = bio_data_dir(bio);		/*
			* Flag this bio as submitted while down.
			*/
			map_context->ll = 1;

	/*		/*
	* Drop writes. Map reads as normal.		* Map reads as normal.
			*/
			if (bio_data_dir(bio) == READ)
			goto map_bio;

			/*
			* Drop writes?
	*/		*/
	if (test_bit(DROP_WRITES, &fc->flags)) {		if (test_bit(DROP_WRITES, &fc->flags)) {
	if (rw == WRITE) {
	bio_endio(bio, 0);		bio_endio(bio, 0);
	return DM_MAPIO_SUBMITTED;		return DM_MAPIO_SUBMITTED;
	}		}

			/*
			* Corrupt matching writes.
			*/
			if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
			if (all_corrupt_bio_flags_match(bio, fc))
			corrupt_bio_data(bio, fc);
	goto map_bio;		goto map_bio;
	}		}

	/*		/*
	* Default setting errors all I/O.		* By default, error all I/O.
	*/		*/
	return -EIO;		return -EIO;
	}		}
	@@ -213,6 +311,24 @@ map_bio:
	return DM_MAPIO_REMAPPED;		return DM_MAPIO_REMAPPED;
	}		}

			static int flakey_end_io(struct dm_target ti, struct bio bio,
			int error, union map_info *map_context)
			{
			struct flakey_c *fc = ti->private;
			unsigned bio_submitted_while_down = map_context->ll;

			/*
			* Corrupt successful READs while in down state.
			* If flags were specified, only corrupt those that match.
			*/
			if (!error && bio_submitted_while_down &&
			(bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
			all_corrupt_bio_flags_match(bio, fc))
			corrupt_bio_data(bio, fc);

			return error;
			}

	static int flakey_status(struct dm_target *ti, status_type_t type,		static int flakey_status(struct dm_target *ti, status_type_t type,
	char *result, unsigned int maxlen)		char *result, unsigned int maxlen)
	{		{
	@@ -231,9 +347,17 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
	fc->down_interval);		fc->down_interval);

	drop_writes = test_bit(DROP_WRITES, &fc->flags);		drop_writes = test_bit(DROP_WRITES, &fc->flags);
	DMEMIT("%u ", drop_writes);		DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);

	if (drop_writes)		if (drop_writes)
	DMEMIT("drop_writes ");		DMEMIT("drop_writes ");

			if (fc->corrupt_bio_byte)
			DMEMIT("corrupt_bio_byte %u %c %u %u ",
			fc->corrupt_bio_byte,
			(fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
			fc->corrupt_bio_value, fc->corrupt_bio_flags);

	break;		break;
	}		}
	return 0;		return 0;
	@@ -275,6 +399,7 @@ static struct target_type flakey_target = {
	.ctr = flakey_ctr,		.ctr = flakey_ctr,
	.dtr = flakey_dtr,		.dtr = flakey_dtr,
	.map = flakey_map,		.map = flakey_map,
			.end_io = flakey_end_io,
	.status = flakey_status,		.status = flakey_status,
	.ioctl = flakey_ioctl,		.ioctl = flakey_ioctl,
	.merge = flakey_merge,		.merge = flakey_merge,