Rename the "in_bh" / "use_bh" fields to indicate the work is done
in-line, not in the "bottom half" (as a synonym to softirq). In
certain situations (e.g. dm-verity on top of a loopback device)
the verification will not be done in a softirq context but in a
task context.
There are no functional changes to the code.
Signed-off-by: Eran Messeri <eranm@xxxxxxxxxx>
---
drivers/md/dm-verity-target.c | 85 ++++++++++++++++++++---------------
drivers/md/dm-verity.h | 10 +++--
2 files changed, 55 insertions(+), 40 deletions(-)
diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index 66a00a8ccb39..be9f6d9fccf4 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -29,7 +29,7 @@
#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
-#define DM_VERITY_USE_BH_DEFAULT_BYTES 8192
+#define DM_VERITY_DEFAULT_MAX_INLINE_SIZE 8192
#define DM_VERITY_MAX_CORRUPTED_ERRS 100
@@ -49,16 +49,16 @@ static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE
module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
-static unsigned int dm_verity_use_bh_bytes[4] = {
- DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_NONE
- DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_RT
- DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_BE
+static unsigned int dm_verity_max_inline_size_bytes[4] = {
+ DM_VERITY_DEFAULT_MAX_INLINE_SIZE, // IOPRIO_CLASS_NONE
+ DM_VERITY_DEFAULT_MAX_INLINE_SIZE, // IOPRIO_CLASS_RT
+ DM_VERITY_DEFAULT_MAX_INLINE_SIZE, // IOPRIO_CLASS_BE
0 // IOPRIO_CLASS_IDLE
};
-module_param_array_named(use_bh_bytes, dm_verity_use_bh_bytes, uint, NULL, 0644);
+module_param_array_named(use_bh_bytes, dm_verity_max_inline_size_bytes, uint, NULL, 0644);
-static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
+static DEFINE_STATIC_KEY_FALSE(inline_verification_enabled);
struct dm_verity_prefetch_work {
struct work_struct work;
@@ -236,13 +236,14 @@ static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
verity_hash_at_level(v, block, level, &hash_block, &offset);
- if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
+ if (static_branch_unlikely(&inline_verification_enabled) &&
+ !io->may_sleep) {
data = dm_bufio_get(v->bufio, hash_block, &buf);
if (IS_ERR_OR_NULL(data)) {
/*
- * In tasklet and the hash was not in the bufio cache.
- * Return early and resume execution from a work-queue
- * to read the hash from disk.
+ * In atomic context and the hash was not in the bufio
+ * cache. Return early and resume execution from a
+ * work-queue to read the hash from disk.
*/
return -EAGAIN;
}
@@ -286,10 +287,12 @@ static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
v->digest_size) == 0))
aux->hash_verified = 1;
- else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
+ else if (static_branch_unlikely(&inline_verification_enabled) &&
+ !io->may_sleep) {
/*
- * Error handling code (FEC included) cannot be run in a
- * tasklet since it may sleep, so fallback to work-queue.
+ * Error handling code (FEC included) cannot be run in
+ * atomic context since it may sleep,
+ * so fallback to work-queue.
*/
r = -EAGAIN;
goto release_ret_r;
@@ -405,10 +408,11 @@ static int verity_handle_data_hash_mismatch(struct dm_verity *v,
struct bio *bio, sector_t blkno,
u8 *data)
{
- if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
+ if (static_branch_unlikely(&inline_verification_enabled) &&
+ !io->may_sleep) {
/*
- * Error handling code (FEC included) cannot be run in the
- * BH workqueue, so fallback to a standard workqueue.
+ * Error handling code (FEC included) cannot be run in atomic
+ * context so fallback to a standard workqueue.
*/
return -EAGAIN;
}
@@ -445,7 +449,8 @@ static int verity_verify_io(struct dm_verity_io *io)
struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
unsigned int b;
- if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
+ if (static_branch_unlikely(&inline_verification_enabled) &&
+ !io->may_sleep) {
/*
* Copy the iterator in case we need to restart
* verification in a work-queue.
@@ -546,7 +551,8 @@ static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
bio->bi_end_io = io->orig_bi_end_io;
bio->bi_status = status;
- if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
+ if (!static_branch_unlikely(&inline_verification_enabled) ||
+ io->may_sleep)
verity_fec_finish_io(io);
if (unlikely(status != BLK_STS_OK) &&
@@ -574,17 +580,22 @@ static void verity_work(struct work_struct *w)
{
struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
- io->in_bh = false;
+ io->may_sleep = true;
verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
}
-static void verity_bh_work(struct work_struct *w)
+static void verity_verify_inline(struct work_struct *w)
{
- struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
+ struct dm_verity_io *io = container_of(w, struct dm_verity_io, inline_work);
int err;
- io->in_bh = true;
+ /*
+ * Set may_sleep to false here regardless of the context for simplicity.
+ * This ensures that we do not try to read missing hashes in contexts
+ * where we should not block.
+ */
+ io->may_sleep = false;
err = verity_verify_io(io);
if (err == -EAGAIN || err == -ENOMEM) {
/* fallback to retrying with work-queue */
@@ -596,10 +607,10 @@ static void verity_bh_work(struct work_struct *w)
verity_finish_io(io, errno_to_blk_status(err));
}
-static inline bool verity_use_bh(unsigned int bytes, unsigned short ioprio)
+static inline bool verity_should_verify_inline(unsigned int bytes, unsigned short ioprio)
{
return ioprio <= IOPRIO_CLASS_IDLE &&
- bytes <= READ_ONCE(dm_verity_use_bh_bytes[ioprio]) &&
+ bytes <= READ_ONCE(dm_verity_max_inline_size_bytes[ioprio]) &&
!need_resched();
}
@@ -617,13 +628,13 @@ static void verity_end_io(struct bio *bio)
return;
}
- if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq &&
- verity_use_bh(bytes, ioprio)) {
+ if (static_branch_unlikely(&inline_verification_enabled) && io->v->verify_inline &&
+ verity_should_verify_inline(bytes, ioprio)) {
if (in_hardirq() || irqs_disabled()) {
- INIT_WORK(&io->bh_work, verity_bh_work);
- queue_work(system_bh_wq, &io->bh_work);
+ INIT_WORK(&io->inline_work, verity_verify_inline);
+ queue_work(system_bh_wq, &io->inline_work);
} else {
- verity_bh_work(&io->bh_work);
+ verity_verify_inline(&io->inline_work);
}
} else {
INIT_WORK(&io->work, verity_work);
@@ -805,7 +816,7 @@ static void verity_status(struct dm_target *ti, status_type_t type,
args++;
if (v->validated_blocks)
args++;
- if (v->use_bh_wq)
+ if (v->verify_inline)
args++;
if (v->signature_key_desc)
args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
@@ -845,7 +856,7 @@ static void verity_status(struct dm_target *ti, status_type_t type,
DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
if (v->validated_blocks)
DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
- if (v->use_bh_wq)
+ if (v->verify_inline)
DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
sz = verity_fec_status_table(v, sz, result, maxlen);
if (v->signature_key_desc)
@@ -1023,8 +1034,8 @@ static void verity_dtr(struct dm_target *ti)
kfree(v->signature_key_desc);
- if (v->use_bh_wq)
- static_branch_dec(&use_bh_wq_enabled);
+ if (v->verify_inline)
+ static_branch_dec(&inline_verification_enabled);
kfree(v);
@@ -1194,8 +1205,8 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
continue;
} else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
- v->use_bh_wq = true;
- static_branch_inc(&use_bh_wq_enabled);
+ v->verify_inline = true;
+ static_branch_inc(&inline_verification_enabled);
continue;
} else if (verity_is_fec_opt_arg(arg_name)) {
@@ -1526,7 +1537,7 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
dm_bufio_alloc_callback, NULL,
- v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
+ v->verify_inline ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
if (IS_ERR(v->bufio)) {
ti->error = "Cannot initialize dm-bufio";
r = PTR_ERR(v->bufio);
diff --git a/drivers/md/dm-verity.h b/drivers/md/dm-verity.h
index 6d141abd965c..1a5233c92e54 100644
--- a/drivers/md/dm-verity.h
+++ b/drivers/md/dm-verity.h
@@ -58,7 +58,7 @@ struct dm_verity {
unsigned char levels; /* the number of tree levels */
unsigned char version;
bool hash_failed:1; /* set if hash of any block failed */
- bool use_bh_wq:1; /* try to verify in BH wq before normal work-queue */
+ bool verify_inline:1; /* try to verify inline before normal work-queue */
unsigned int digest_size; /* digest size for the current hash algorithm */
enum verity_mode mode; /* mode for handling verification errors */
enum verity_mode error_mode;/* mode for handling I/O errors */
@@ -88,11 +88,15 @@ struct dm_verity_io {
sector_t block;
unsigned int n_blocks;
- bool in_bh;
+ /*
+ * Keeps track of whether the request is being processed in
+ * the kworker or inline.
+ */
+ bool may_sleep;
bool had_mismatch;
struct work_struct work;
- struct work_struct bh_work;
+ struct work_struct inline_work;
u8 real_digest[HASH_MAX_DIGESTSIZE];
u8 want_digest[HASH_MAX_DIGESTSIZE];
--
2.50.0.727.gbf7dc18ff4-goog
