6.15-stable review patch. If anyone has any objections, please let me know.
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From: Benjamin Marzinski bmarzins@redhat.com
[ Upstream commit 13e79076c89f6e96a6cca8f6df38b40d025907b4 ]
dm-flakey corrupts the read bios in the endio function. However, the corrupt_bio_* functions checked bio_has_data() to see if there was data to corrupt. Since this was the endio function, there was no data left to complete, so bio_has_data() was always false. Fix this by saving a copy of the bio's bi_iter in flakey_map(), and using this to initialize the iter for corrupting the read bios. This patch also skips cloning the bio for write bios with no data.
Reported-by: Kent Overstreet kent.overstreet@linux.dev Fixes: a3998799fb4df ("dm flakey: add corrupt_bio_byte feature") Signed-off-by: Benjamin Marzinski bmarzins@redhat.com Signed-off-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-flakey.c | 54 ++++++++++++++++++++++-------------------- 1 file changed, 28 insertions(+), 26 deletions(-)
diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c index 806a80dd3bd9b..347881f323d5b 100644 --- a/drivers/md/dm-flakey.c +++ b/drivers/md/dm-flakey.c @@ -47,7 +47,8 @@ enum feature_flag_bits { };
struct per_bio_data { - bool bio_submitted; + bool bio_can_corrupt; + struct bvec_iter saved_iter; };
static int parse_features(struct dm_arg_set *as, struct flakey_c *fc, @@ -339,7 +340,8 @@ static void flakey_map_bio(struct dm_target *ti, struct bio *bio) }
static void corrupt_bio_common(struct bio *bio, unsigned int corrupt_bio_byte, - unsigned char corrupt_bio_value) + unsigned char corrupt_bio_value, + struct bvec_iter start) { struct bvec_iter iter; struct bio_vec bvec; @@ -348,7 +350,7 @@ static void corrupt_bio_common(struct bio *bio, unsigned int corrupt_bio_byte, * Overwrite the Nth byte of the bio's data, on whichever page * it falls. */ - bio_for_each_segment(bvec, bio, iter) { + __bio_for_each_segment(bvec, bio, iter, start) { if (bio_iter_len(bio, iter) > corrupt_bio_byte) { unsigned char *segment = bvec_kmap_local(&bvec); segment[corrupt_bio_byte] = corrupt_bio_value; @@ -357,36 +359,31 @@ static void corrupt_bio_common(struct bio *bio, unsigned int corrupt_bio_byte, "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n", bio, corrupt_bio_value, corrupt_bio_byte, (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf, - (unsigned long long)bio->bi_iter.bi_sector, - bio->bi_iter.bi_size); + (unsigned long long)start.bi_sector, + start.bi_size); break; } corrupt_bio_byte -= bio_iter_len(bio, iter); } }
-static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc) +static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc, + struct bvec_iter start) { unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
- if (!bio_has_data(bio)) - return; - - corrupt_bio_common(bio, corrupt_bio_byte, fc->corrupt_bio_value); + corrupt_bio_common(bio, corrupt_bio_byte, fc->corrupt_bio_value, start); }
-static void corrupt_bio_random(struct bio *bio) +static void corrupt_bio_random(struct bio *bio, struct bvec_iter start) { unsigned int corrupt_byte; unsigned char corrupt_value;
- if (!bio_has_data(bio)) - return; - - corrupt_byte = get_random_u32() % bio->bi_iter.bi_size; + corrupt_byte = get_random_u32() % start.bi_size; corrupt_value = get_random_u8();
- corrupt_bio_common(bio, corrupt_byte, corrupt_value); + corrupt_bio_common(bio, corrupt_byte, corrupt_value, start); }
static void clone_free(struct bio *clone) @@ -481,7 +478,7 @@ static int flakey_map(struct dm_target *ti, struct bio *bio) unsigned int elapsed; struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
- pb->bio_submitted = false; + pb->bio_can_corrupt = false;
if (op_is_zone_mgmt(bio_op(bio))) goto map_bio; @@ -490,10 +487,11 @@ static int flakey_map(struct dm_target *ti, struct bio *bio) elapsed = (jiffies - fc->start_time) / HZ; if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) { bool corrupt_fixed, corrupt_random; - /* - * Flag this bio as submitted while down. - */ - pb->bio_submitted = true; + + if (bio_has_data(bio)) { + pb->bio_can_corrupt = true; + pb->saved_iter = bio->bi_iter; + }
/* * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set. @@ -516,6 +514,8 @@ static int flakey_map(struct dm_target *ti, struct bio *bio) return DM_MAPIO_SUBMITTED; }
+ if (!pb->bio_can_corrupt) + goto map_bio; /* * Corrupt matching writes. */ @@ -535,9 +535,11 @@ static int flakey_map(struct dm_target *ti, struct bio *bio) struct bio *clone = clone_bio(ti, fc, bio); if (clone) { if (corrupt_fixed) - corrupt_bio_data(clone, fc); + corrupt_bio_data(clone, fc, + clone->bi_iter); if (corrupt_random) - corrupt_bio_random(clone); + corrupt_bio_random(clone, + clone->bi_iter); submit_bio(clone); return DM_MAPIO_SUBMITTED; } @@ -559,21 +561,21 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio, if (op_is_zone_mgmt(bio_op(bio))) return DM_ENDIO_DONE;
- if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) { + if (!*error && pb->bio_can_corrupt && (bio_data_dir(bio) == READ)) { if (fc->corrupt_bio_byte) { if ((fc->corrupt_bio_rw == READ) && all_corrupt_bio_flags_match(bio, fc)) { /* * Corrupt successful matching READs while in down state. */ - corrupt_bio_data(bio, fc); + corrupt_bio_data(bio, fc, pb->saved_iter); } } if (fc->random_read_corrupt) { u64 rnd = get_random_u64(); u32 rem = do_div(rnd, PROBABILITY_BASE); if (rem < fc->random_read_corrupt) - corrupt_bio_random(bio); + corrupt_bio_random(bio, pb->saved_iter); } if (test_bit(ERROR_READS, &fc->flags)) { /*