1 files changed, 244 insertions, 26 deletions

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index ea79062..89f73ca 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -1,6 +1,6 @@
 /*
  * 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.
  */
@@ -15,6 +15,9 @@
 
 #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,
  * catastrophic device failure.
@@ -25,60 +28,189 @@ struct flakey_c {
 	sector_t start;
 	unsigned up_interval;
 	unsigned down_interval;
+	unsigned long flags;
+	unsigned corrupt_bio_byte;
+	unsigned corrupt_bio_rw;
+	unsigned corrupt_bio_value;
+	unsigned corrupt_bio_flags;
+};
+
+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, 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. */
+	if (!as->argc)
+		return 0;
+
+	r = dm_read_arg_group(_args, as, &argc, &ti->error);
+	if (r)
+		return r;
+
+	while (argc) {
+		arg_name = dm_shift_arg(as);
+		argc--;
+
+		/*
+		 * drop_writes
+		 */
+		if (!strcasecmp(arg_name, "drop_writes")) {
+			if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
+				ti->error = "Feature drop_writes duplicated";
+				return -EINVAL;
+			}
+
+			continue;
+		}
+
+		/*
+		 * 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;
+			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;
+}
+
 /*
- * Construct a flakey mapping: <dev_path> <offset> <up interval> <down interval>
+ * Construct a flakey mapping:
+ * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
+ *
+ *   Feature args:
+ *     [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 struct dm_arg _args[] = {
+		{0, UINT_MAX, "Invalid up interval"},
+		{0, UINT_MAX, "Invalid down interval"},
+	};
+
+	int r;
 	struct flakey_c *fc;
-	unsigned long long tmp;
+	unsigned long long tmpll;
+	struct dm_arg_set as;
+	const char *devname;
 
-	if (argc != 4) {
-		ti->error = "dm-flakey: Invalid argument count";
+	as.argc = argc;
+	as.argv = argv;
+
+	if (argc < 4) {
+		ti->error = "Invalid argument count";
 		return -EINVAL;
 	}
 
-	fc = kmalloc(sizeof(*fc), GFP_KERNEL);
+	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 	if (!fc) {
-		ti->error = "dm-flakey: Cannot allocate linear context";
+		ti->error = "Cannot allocate linear context";
 		return -ENOMEM;
 	}
 	fc->start_time = jiffies;
 
-	if (sscanf(argv[1], "%llu", &tmp) != 1) {
-		ti->error = "dm-flakey: Invalid device sector";
+	devname = dm_shift_arg(&as);
+
+	if (sscanf(dm_shift_arg(&as), "%llu", &tmpll) != 1) {
+		ti->error = "Invalid device sector";
 		goto bad;
 	}
-	fc->start = tmp;
+	fc->start = tmpll;
 
-	if (sscanf(argv[2], "%u", &fc->up_interval) != 1) {
-		ti->error = "dm-flakey: Invalid up interval";
+	r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
+	if (r)
 		goto bad;
-	}
 
-	if (sscanf(argv[3], "%u", &fc->down_interval) != 1) {
-		ti->error = "dm-flakey: Invalid down interval";
+	r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
+	if (r)
 		goto bad;
-	}
 
 	if (!(fc->up_interval + fc->down_interval)) {
-		ti->error = "dm-flakey: Total (up + down) interval is zero";
+		ti->error = "Total (up + down) interval is zero";
 		goto bad;
 	}
 
 	if (fc->up_interval + fc->down_interval < fc->up_interval) {
-		ti->error = "dm-flakey: Interval overflow";
+		ti->error = "Interval overflow";
 		goto bad;
 	}
 
-	if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &fc->dev)) {
-		ti->error = "dm-flakey: Device lookup failed";
+	r = parse_features(&as, fc, ti);
+	if (r)
+		goto bad;
+
+	if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
+		ti->error = "Device lookup failed";
 		goto bad;
 	}
 
 	ti->num_flush_requests = 1;
+	ti->num_discard_requests = 1;
 	ti->private = fc;
 	return 0;
 
@@ -99,7 +231,7 @@ static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 {
 	struct flakey_c *fc = ti->private;
 
-	return fc->start + (bi_sector - ti->begin);
+	return fc->start + dm_target_offset(ti, bi_sector);
 }
 
 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
@@ -111,6 +243,25 @@ static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
 		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,
 		      union map_info *map_context)
 {
@@ -119,18 +270,71 @@ 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) {
+		/*
+		 * Flag this bio as submitted while down.
+		 */
+		map_context->ll = 1;
+
+		/*
+		 * Map reads as normal.
+		 */
+		if (bio_data_dir(bio) == READ)
+			goto map_bio;
+
+		/*
+		 * Drop writes?
+		 */
+		if (test_bit(DROP_WRITES, &fc->flags)) {
+			bio_endio(bio, 0);
+			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;
+		}
+
+		/*
+		 * By default, error all I/O.
+		 */
 		return -EIO;
+	}
 
+map_bio:
 	flakey_map_bio(ti, bio);
 
 	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,
 			 char *result, unsigned int maxlen)
 {
+	unsigned sz = 0;
 	struct flakey_c *fc = ti->private;
+	unsigned drop_writes;
 
 	switch (type) {
 	case STATUSTYPE_INFO:
@@ -138,9 +342,22 @@ 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 + (fc->corrupt_bio_byte > 0) * 5);
+
+		if (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;
 	}
 	return 0;
@@ -177,11 +394,12 @@ static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_
 
 static struct target_type flakey_target = {
 	.name   = "flakey",
-	.version = {1, 1, 0},
+	.version = {1, 2, 0},
 	.module = THIS_MODULE,
 	.ctr    = flakey_ctr,
 	.dtr    = flakey_dtr,
 	.map    = flakey_map,
+	.end_io = flakey_end_io,
 	.status = flakey_status,
 	.ioctl	= flakey_ioctl,
 	.merge	= flakey_merge,