1 files changed, 442 insertions, 0 deletions

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
new file mode 100644
index 00000000..ac49c01f
--- /dev/null
+++ b/drivers/md/dm-flakey.c
@@ -0,0 +1,442 @@
+/*
+ * Copyright (C) 2003 Sistina Software (UK) Limited.
+ * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/device-mapper.h>
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/slab.h>
+
+#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.
+ */
+struct flakey_c {
+	struct dm_dev *dev;
+	unsigned long start_time;
+	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";
+				return -EINVAL;
+			}
+
+			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> [<#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 tmpll;
+	struct dm_arg_set as;
+	const char *devname;
+	char dummy;
+
+	as.argc = argc;
+	as.argv = argv;
+
+	if (argc < 4) {
+		ti->error = "Invalid argument count";
+		return -EINVAL;
+	}
+
+	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
+	if (!fc) {
+		ti->error = "Cannot allocate linear context";
+		return -ENOMEM;
+	}
+	fc->start_time = jiffies;
+
+	devname = dm_shift_arg(&as);
+
+	if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
+		ti->error = "Invalid device sector";
+		goto bad;
+	}
+	fc->start = tmpll;
+
+	r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
+	if (r)
+		goto bad;
+
+	r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
+	if (r)
+		goto bad;
+
+	if (!(fc->up_interval + fc->down_interval)) {
+		ti->error = "Total (up + down) interval is zero";
+		goto bad;
+	}
+
+	if (fc->up_interval + fc->down_interval < fc->up_interval) {
+		ti->error = "Interval overflow";
+		goto bad;
+	}
+
+	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;
+
+bad:
+	kfree(fc);
+	return -EINVAL;
+}
+
+static void flakey_dtr(struct dm_target *ti)
+{
+	struct flakey_c *fc = ti->private;
+
+	dm_put_device(ti, fc->dev);
+	kfree(fc);
+}
+
+static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
+{
+	struct flakey_c *fc = ti->private;
+
+	return fc->start + dm_target_offset(ti, bi_sector);
+}
+
+static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
+{
+	struct flakey_c *fc = ti->private;
+
+	bio->bi_bdev = fc->dev->bdev;
+	if (bio_sectors(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)
+{
+	struct flakey_c *fc = ti->private;
+	unsigned elapsed;
+
+	/* Are we alive ? */
+	elapsed = (jiffies - fc->start_time) / HZ;
+	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 (fc->corrupt_bio_byte && !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:
+		result[0] = '\0';
+		break;
+
+	case STATUSTYPE_TABLE:
+		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;
+}
+
+static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
+{
+	struct flakey_c *fc = ti->private;
+	struct dm_dev *dev = fc->dev;
+	int r = 0;
+
+	/*
+	 * Only pass ioctls through if the device sizes match exactly.
+	 */
+	if (fc->start ||
+	    ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
+		r = scsi_verify_blk_ioctl(NULL, cmd);
+
+	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
+}
+
+static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+			struct bio_vec *biovec, int max_size)
+{
+	struct flakey_c *fc = ti->private;
+	struct request_queue *q = bdev_get_queue(fc->dev->bdev);
+
+	if (!q->merge_bvec_fn)
+		return max_size;
+
+	bvm->bi_bdev = fc->dev->bdev;
+	bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
+
+	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
+static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
+{
+	struct flakey_c *fc = ti->private;
+
+	return fn(ti, fc->dev, fc->start, ti->len, data);
+}
+
+static struct target_type flakey_target = {
+	.name   = "flakey",
+	.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,
+	.iterate_devices = flakey_iterate_devices,
+};
+
+static int __init dm_flakey_init(void)
+{
+	int r = dm_register_target(&flakey_target);
+
+	if (r < 0)
+		DMERR("register failed %d", r);
+
+	return r;
+}
+
+static void __exit dm_flakey_exit(void)
+{
+	dm_unregister_target(&flakey_target);
+}
+
+/* Module hooks */
+module_init(dm_flakey_init);
+module_exit(dm_flakey_exit);
+
+MODULE_DESCRIPTION(DM_NAME " flakey target");
+MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");