diff options
| -rw-r--r-- | Documentation/device-mapper/dm-flakey.txt | 17 | ||||
| -rw-r--r-- | drivers/md/Kconfig | 6 | ||||
| -rw-r--r-- | drivers/md/Makefile | 1 | ||||
| -rw-r--r-- | drivers/md/dm-flakey.c | 212 |
4 files changed, 236 insertions, 0 deletions
diff --git a/Documentation/device-mapper/dm-flakey.txt b/Documentation/device-mapper/dm-flakey.txt new file mode 100644 index 0000000..c8efdfd --- /dev/null +++ b/Documentation/device-mapper/dm-flakey.txt @@ -0,0 +1,17 @@ +dm-flakey +========= + +This target is the same as the linear target except that it returns I/O +errors periodically. It's been found useful in simulating failing +devices for testing purposes. + +Starting from the time the table is loaded, the device is available for +<up interval> seconds, then returns errors for <down interval> seconds, +and then this cycle repeats. + +Parameters: <dev path> <offset> <up interval> <down interval> + <dev path>: Full pathname to the underlying block-device, or a + "major:minor" device-number. + <offset>: Starting sector within the device. + <up interval>: Number of seconds device is available. + <down interval>: Number of seconds device returns errors. diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index 98d9ec8..8420129 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -327,4 +327,10 @@ config DM_UEVENT ---help--- Generate udev events for DM events. +config DM_FLAKEY + tristate "Flakey target (EXPERIMENTAL)" + depends on BLK_DEV_DM && EXPERIMENTAL + ---help--- + A target that intermittently fails I/O for debugging purposes. + endif # MD diff --git a/drivers/md/Makefile b/drivers/md/Makefile index d013860..448838b 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -29,6 +29,7 @@ obj-$(CONFIG_BLK_DEV_MD) += md-mod.o obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o obj-$(CONFIG_DM_CRYPT) += dm-crypt.o obj-$(CONFIG_DM_DELAY) += dm-delay.o +obj-$(CONFIG_DM_FLAKEY) += dm-flakey.o obj-$(CONFIG_DM_MULTIPATH) += dm-multipath.o dm-round-robin.o obj-$(CONFIG_DM_MULTIPATH_QL) += dm-queue-length.o obj-$(CONFIG_DM_MULTIPATH_ST) += dm-service-time.o diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c new file mode 100644 index 0000000..ea79062 --- /dev/null +++ b/drivers/md/dm-flakey.c @@ -0,0 +1,212 @@ +/* + * Copyright (C) 2003 Sistina Software (UK) Limited. + * Copyright (C) 2004, 2010 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" + +/* + * 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; +}; + +/* + * Construct a flakey mapping: <dev_path> <offset> <up interval> <down interval> + */ +static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv) +{ + struct flakey_c *fc; + unsigned long long tmp; + + if (argc != 4) { + ti->error = "dm-flakey: Invalid argument count"; + return -EINVAL; + } + + fc = kmalloc(sizeof(*fc), GFP_KERNEL); + if (!fc) { + ti->error = "dm-flakey: Cannot allocate linear context"; + return -ENOMEM; + } + fc->start_time = jiffies; + + if (sscanf(argv[1], "%llu", &tmp) != 1) { + ti->error = "dm-flakey: Invalid device sector"; + goto bad; + } + fc->start = tmp; + + if (sscanf(argv[2], "%u", &fc->up_interval) != 1) { + ti->error = "dm-flakey: Invalid up interval"; + goto bad; + } + + if (sscanf(argv[3], "%u", &fc->down_interval) != 1) { + ti->error = "dm-flakey: Invalid down interval"; + goto bad; + } + + if (!(fc->up_interval + fc->down_interval)) { + ti->error = "dm-flakey: Total (up + down) interval is zero"; + goto bad; + } + + if (fc->up_interval + fc->down_interval < fc->up_interval) { + ti->error = "dm-flakey: 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"; + goto bad; + } + + ti->num_flush_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 + (bi_sector - ti->begin); +} + +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 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) + return -EIO; + + flakey_map_bio(ti, bio); + + return DM_MAPIO_REMAPPED; +} + +static int flakey_status(struct dm_target *ti, status_type_t type, + char *result, unsigned int maxlen) +{ + struct flakey_c *fc = ti->private; + + switch (type) { + case STATUSTYPE_INFO: + result[0] = '\0'; + 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); + break; + } + return 0; +} + +static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg) +{ + struct flakey_c *fc = ti->private; + + return __blkdev_driver_ioctl(fc->dev->bdev, fc->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, 1, 0}, + .module = THIS_MODULE, + .ctr = flakey_ctr, + .dtr = flakey_dtr, + .map = flakey_map, + .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"); |
