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dm flakey: add corrupt_bio_byte feature
Add corrupt_bio_byte feature to simulate corruption by overwriting a byte at a specified position with a specified value during intervals when the device is "down". Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mike Snitzer
Alasdair G Kergon
parent
b26f5e3d71
commit
a3998799fb
2 changed files with 159 additions and 15 deletions
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@ -32,3 +32,22 @@ Optional feature parameters:
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drop_writes:
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All write I/O is silently ignored.
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Read I/O is handled correctly.
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corrupt_bio_byte <Nth_byte> <direction> <value> <flags>:
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During <down interval>, replace <Nth_byte> of the data of
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each matching bio with <value>.
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<Nth_byte>: The offset of the byte to replace.
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Counting starts at 1, to replace the first byte.
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<direction>: Either 'r' to corrupt reads or 'w' to corrupt writes.
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'w' is incompatible with drop_writes.
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<value>: The value (from 0-255) to write.
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<flags>: Perform the replacement only if bio->bi_rw has all the
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selected flags set.
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Examples:
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corrupt_bio_byte 32 r 1 0
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- replaces the 32nd byte of READ bios with the value 1
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corrupt_bio_byte 224 w 0 32
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- replaces the 224th byte of REQ_META (=32) bios with the value 0
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@ -1,6 +1,6 @@
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/*
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* Copyright (C) 2003 Sistina Software (UK) Limited.
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* Copyright (C) 2004, 2010 Red Hat, Inc. All rights reserved.
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* Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
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*
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* This file is released under the GPL.
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*/
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@ -15,6 +15,9 @@
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#define DM_MSG_PREFIX "flakey"
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#define all_corrupt_bio_flags_match(bio, fc) \
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(((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
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/*
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* Flakey: Used for testing only, simulates intermittent,
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* catastrophic device failure.
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@ -26,6 +29,10 @@ struct flakey_c {
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unsigned up_interval;
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unsigned down_interval;
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unsigned long flags;
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unsigned corrupt_bio_byte;
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unsigned corrupt_bio_rw;
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unsigned corrupt_bio_value;
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unsigned corrupt_bio_flags;
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};
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enum feature_flag_bits {
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@ -40,7 +47,10 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
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const char *arg_name;
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static struct dm_arg _args[] = {
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{0, 1, "Invalid number of feature args"},
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{0, 6, "Invalid number of feature args"},
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{1, UINT_MAX, "Invalid corrupt bio byte"},
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{0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
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{0, UINT_MAX, "Invalid corrupt bio flags mask"},
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};
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/* No feature arguments supplied. */
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@ -49,9 +59,9 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
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r = dm_read_arg_group(_args, as, &argc, &ti->error);
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if (r)
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return -EINVAL;
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return r;
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while (argc && !r) {
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while (argc) {
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arg_name = dm_shift_arg(as);
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argc--;
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@ -67,11 +77,61 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
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continue;
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}
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/*
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* corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
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*/
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if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
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if (!argc)
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ti->error = "Feature corrupt_bio_byte requires parameters";
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r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
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if (r)
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return r;
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argc--;
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/*
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* Direction r or w?
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*/
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arg_name = dm_shift_arg(as);
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if (!strcasecmp(arg_name, "w"))
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fc->corrupt_bio_rw = WRITE;
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else if (!strcasecmp(arg_name, "r"))
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fc->corrupt_bio_rw = READ;
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else {
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ti->error = "Invalid corrupt bio direction (r or w)";
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return -EINVAL;
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}
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argc--;
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/*
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* Value of byte (0-255) to write in place of correct one.
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*/
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r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
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if (r)
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return r;
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argc--;
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/*
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* Only corrupt bios with these flags set.
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*/
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r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
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if (r)
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return r;
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argc--;
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continue;
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}
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ti->error = "Unrecognised flakey feature requested";
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r = -EINVAL;
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return -EINVAL;
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}
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return r;
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if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
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ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
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return -EINVAL;
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}
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return 0;
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}
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/*
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@ -80,6 +140,11 @@ static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
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*
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* Feature args:
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* [drop_writes]
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* [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
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*
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* Nth_byte starts from 1 for the first byte.
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* Direction is r for READ or w for WRITE.
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* bio_flags is ignored if 0.
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*/
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static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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{
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@ -178,31 +243,64 @@ static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
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bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
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}
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static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
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{
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unsigned bio_bytes = bio_cur_bytes(bio);
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char *data = bio_data(bio);
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/*
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* Overwrite the Nth byte of the data returned.
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*/
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if (data && bio_bytes >= fc->corrupt_bio_byte) {
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data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
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DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
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"(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
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bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
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(bio_data_dir(bio) == WRITE) ? 'w' : 'r',
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bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
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}
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}
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static int flakey_map(struct dm_target *ti, struct bio *bio,
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union map_info *map_context)
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{
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struct flakey_c *fc = ti->private;
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unsigned elapsed;
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unsigned rw;
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/* Are we alive ? */
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elapsed = (jiffies - fc->start_time) / HZ;
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if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
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rw = bio_data_dir(bio);
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/*
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* Flag this bio as submitted while down.
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*/
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map_context->ll = 1;
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/*
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* Drop writes. Map reads as normal.
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* Map reads as normal.
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*/
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if (bio_data_dir(bio) == READ)
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goto map_bio;
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/*
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* Drop writes?
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*/
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if (test_bit(DROP_WRITES, &fc->flags)) {
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if (rw == WRITE) {
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bio_endio(bio, 0);
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return DM_MAPIO_SUBMITTED;
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}
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bio_endio(bio, 0);
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return DM_MAPIO_SUBMITTED;
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}
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/*
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* Corrupt matching writes.
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*/
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if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
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if (all_corrupt_bio_flags_match(bio, fc))
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corrupt_bio_data(bio, fc);
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goto map_bio;
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}
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/*
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* Default setting errors all I/O.
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* By default, error all I/O.
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*/
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return -EIO;
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}
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@ -213,6 +311,24 @@ static int flakey_map(struct dm_target *ti, struct bio *bio,
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return DM_MAPIO_REMAPPED;
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}
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static int flakey_end_io(struct dm_target *ti, struct bio *bio,
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int error, union map_info *map_context)
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{
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struct flakey_c *fc = ti->private;
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unsigned bio_submitted_while_down = map_context->ll;
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/*
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* Corrupt successful READs while in down state.
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* If flags were specified, only corrupt those that match.
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*/
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if (!error && bio_submitted_while_down &&
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(bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
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all_corrupt_bio_flags_match(bio, fc))
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corrupt_bio_data(bio, fc);
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return error;
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}
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static int flakey_status(struct dm_target *ti, status_type_t type,
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char *result, unsigned int maxlen)
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{
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@ -231,9 +347,17 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
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fc->down_interval);
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drop_writes = test_bit(DROP_WRITES, &fc->flags);
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DMEMIT("%u ", drop_writes);
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DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
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if (drop_writes)
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DMEMIT("drop_writes ");
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if (fc->corrupt_bio_byte)
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DMEMIT("corrupt_bio_byte %u %c %u %u ",
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fc->corrupt_bio_byte,
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(fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
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fc->corrupt_bio_value, fc->corrupt_bio_flags);
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break;
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}
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return 0;
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@ -275,6 +399,7 @@ static struct target_type flakey_target = {
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.ctr = flakey_ctr,
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.dtr = flakey_dtr,
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.map = flakey_map,
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.end_io = flakey_end_io,
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.status = flakey_status,
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.ioctl = flakey_ioctl,
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.merge = flakey_merge,
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