linux/drivers/md/dm-flakey.c

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/*
* 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.
*/
dm flakey: fix crash on read when corrupt_bio_byte not set The following BUG is hit on the first read that is submitted to a dm flakey test device while the device is "down" if the corrupt_bio_byte feature wasn't requested when the device's table was loaded. Example DM table that will hit this BUG: 0 2097152 flakey 8:0 2048 0 30 This bug was introduced by commit a3998799fb4df0b0af8271a7d50c4269032397aa (dm flakey: add corrupt_bio_byte feature) in v3.1-rc1. BUG: unable to handle kernel paging request at ffff8801cfce3fff IP: [<ffffffffa008c233>] corrupt_bio_data+0x6e/0xae [dm_flakey] PGD 1606063 PUD 0 Oops: 0002 [#1] SMP ... Call Trace: <IRQ> [<ffffffffa008c2b5>] flakey_end_io+0x42/0x48 [dm_flakey] [<ffffffffa00dca98>] clone_endio+0x54/0xb6 [dm_mod] [<ffffffff81130587>] bio_endio+0x2d/0x2f [<ffffffff811c819a>] req_bio_endio+0x96/0x9f [<ffffffff811c94b9>] blk_update_request+0x1dc/0x3a9 [<ffffffff812f5ee2>] ? rcu_read_unlock+0x21/0x23 [<ffffffff811c96a6>] blk_update_bidi_request+0x20/0x6e [<ffffffff811c9713>] blk_end_bidi_request+0x1f/0x5d [<ffffffff811c978d>] blk_end_request+0x10/0x12 [<ffffffff8128f450>] scsi_io_completion+0x1e5/0x4b1 [<ffffffff812882a9>] scsi_finish_command+0xec/0xf5 [<ffffffff8128f830>] scsi_softirq_done+0xff/0x108 [<ffffffff811ce284>] blk_done_softirq+0x84/0x98 [<ffffffff81048d19>] __do_softirq+0xe3/0x1d5 [<ffffffff8138f83f>] ? _raw_spin_lock+0x62/0x69 [<ffffffff810997cf>] ? handle_irq_event+0x4c/0x61 [<ffffffff8139833c>] call_softirq+0x1c/0x30 [<ffffffff81003b37>] do_softirq+0x4b/0xa3 [<ffffffff81048a39>] irq_exit+0x53/0xca [<ffffffff81398acd>] do_IRQ+0x9d/0xb4 [<ffffffff81390333>] common_interrupt+0x73/0x73 ... Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org # 3.1+ Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-03-07 19:09:39 +00:00
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,
unsigned status_flags, char *result, unsigned 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");