> Hi
>
> I have found another bug in dm-snapshots, I think it won't fix your crash
> but it is a bug anyway, so it should be fixed. Apply the below patch.
>
> I'll send you some more debug patches to pinpoint the crash you are
> seeing.
>
> Mikulas
Hi
Here is another patch to pinpoint your crashes, so apply it and run the
same workload. Thanks for testing it.
Mikulas
---
drivers/md/dm-exception-store.c | 63 +++++++++++++++++++++++++++++++++++-----
drivers/md/dm-snap.c | 51 +++++++++++++++++++++++++++++---
drivers/md/dm-snap.h | 3 +
3 files changed, 106 insertions(+), 11 deletions(-)
Index: linux-2.6.28-clean/drivers/md/dm-exception-store.c
===================================================================
--- linux-2.6.28-clean.orig/drivers/md/dm-exception-store.c 2009-02-11 00:39:23.000000000 +0100
+++ linux-2.6.28-clean/drivers/md/dm-exception-store.c 2009-02-11 10:33:11.000000000 +0100
@@ -619,14 +619,18 @@ struct dm_snap_pending_exception {
* kcopyd.
*/
int started;
+
+ struct list_head list_all;
};
+static DEFINE_SPINLOCK(callback_spinlock);
+
static void persistent_commit(struct exception_store *store,
struct dm_snap_exception *e,
void (*callback) (void *, int success),
void *callback_context)
{
- unsigned int i;
+ unsigned int i, n;
struct pstore *ps = get_info(store);
struct disk_exception de;
struct commit_callback *cb;
@@ -641,32 +645,41 @@ static void persistent_commit(struct exc
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
- de.old_chunk = e->old_chunk;
- de.new_chunk = e->new_chunk;
- write_exception(ps, ps->current_committed++, &de);
-
for (i = 0; i < ps->callback_count; i++) {
cb = ps->callbacks + i;
pe = cb->context;
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
BUG_ON(pe == callback_context);
+ BUG_ON(pe->started != 2);
+ }
+ for (i = 0; i < ps->current_committed; i++) {
+ read_exception(ps, i, &de);
+ BUG_ON(de.old_chunk == e->old_chunk);
+ BUG_ON(de.new_chunk == e->new_chunk);
}
+ de.old_chunk = e->old_chunk;
+ de.new_chunk = e->new_chunk;
+ write_exception(ps, ps->current_committed++, &de);
+
/*
* Add the callback to the back of the array. This code
* is the only place where the callback array is
* manipulated, and we know that it will never be called
* multiple times concurrently.
*/
+ spin_lock_irq(&callback_spinlock);
cb = ps->callbacks + ps->callback_count++;
cb->callback = callback;
cb->context = callback_context;
+ spin_unlock_irq(&callback_spinlock);
for (i = 0; i < ps->callback_count; i++) {
cb = ps->callbacks + i;
pe = cb->context;
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
+ BUG_ON(pe->started != 2);
}
/*
* If there are exceptions in flight and we have not yet
@@ -677,6 +690,7 @@ static void persistent_commit(struct exc
pe = callback_context;
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
+ BUG_ON(pe->started != 2);
return;
}
for (i = 0; i < ps->callback_count; i++) {
@@ -684,6 +698,7 @@ static void persistent_commit(struct exc
pe = cb->context;
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
+ BUG_ON(pe->started != 2);
}
@@ -714,17 +729,45 @@ static void persistent_commit(struct exc
pe = cb->context;
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
+ BUG_ON(pe->started != 2);
}
- for (i = 0; i < ps->callback_count; i++) {
+ spin_lock_irq(&callback_spinlock);
+ n = ps->callback_count;
+ ps->callback_count = 0;
+ spin_unlock_irq(&callback_spinlock);
+ for (i = 0; i < n; i++) {
cb = ps->callbacks + i;
pe = cb->context;
+ BUG_ON(pe->started != 2);
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
cb->callback(cb->context, ps->valid);
}
+}
- ps->callback_count = 0;
+static void persistent_check(struct exception_store *store, void *context, int line)
+{
+ struct pstore *ps = get_info(store);
+ unsigned long flags;
+ unsigned i;
+ struct commit_callback *cb;
+ struct dm_snap_pending_exception *pe;
+
+ spin_lock_irqsave(&callback_spinlock, flags);
+ for (i = 0; i < ps->callback_count; i++) {
+ cb = ps->callbacks + i;
+ pe = cb->context;
+ if (pe == context) {
+ printk("CALLED FROM LINE %d\n", line);
+ BUG();
+ }
+ if (pe->started != 2) {
+ printk("CALLED FROM LINE %d\n", line);
+ BUG();
+ }
+ }
+ spin_unlock_irqrestore(&callback_spinlock, flags);
}
static void persistent_drop(struct exception_store *store)
@@ -769,6 +812,7 @@ int dm_create_persistent(struct exceptio
store->read_metadata = persistent_read_metadata;
store->prepare_exception = persistent_prepare;
store->commit_exception = persistent_commit;
+ store->check_pending_exception = persistent_check;
store->drop_snapshot = persistent_drop;
store->fraction_full = persistent_fraction_full;
store->context = ps;
@@ -824,6 +868,10 @@ static void transient_fraction_full(stru
*denominator = get_dev_size(store->snap->cow->bdev);
}
+static void transient_check(struct exception_store *store, void *context, int line)
+{
+}
+
int dm_create_transient(struct exception_store *store)
{
struct transient_c *tc;
@@ -832,6 +880,7 @@ int dm_create_transient(struct exception
store->read_metadata = transient_read_metadata;
store->prepare_exception = transient_prepare;
store->commit_exception = transient_commit;
+ store->check_pending_exception = transient_check;
store->drop_snapshot = NULL;
store->fraction_full = transient_fraction_full;
Index: linux-2.6.28-clean/drivers/md/dm-snap.h
===================================================================
--- linux-2.6.28-clean.orig/drivers/md/dm-snap.h 2009-02-11 00:39:36.000000000 +0100
+++ linux-2.6.28-clean/drivers/md/dm-snap.h 2009-02-11 09:54:45.000000000 +0100
@@ -114,6 +114,9 @@ struct exception_store {
void (*callback) (void *, int success),
void *callback_context);
+ void (*check_pending_exception)(struct exception_store *store,
+ void *callback_context, int line);
+
/*
* The snapshot is invalid, note this in the metadata.
*/
Index: linux-2.6.28-clean/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.28-clean.orig/drivers/md/dm-snap.c 2009-02-11 03:15:26.000000000 +0100
+++ linux-2.6.28-clean/drivers/md/dm-snap.c 2009-02-11 10:20:55.000000000 +0100
@@ -88,6 +88,8 @@ struct dm_snap_pending_exception {
* kcopyd.
*/
int started;
+
+ struct list_head list_all;
};
/*
@@ -365,20 +367,45 @@ static void free_exception(struct dm_sna
kmem_cache_free(exception_cache, e);
}
+static DEFINE_SPINLOCK(pending_spinlock);
+static LIST_HEAD(pending_all);
+
static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s)
{
struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool,
GFP_NOIO);
+ struct dm_snap_pending_exception *pe2;
atomic_inc(&s->pending_exceptions_count);
pe->snap = s;
+ spin_lock(&pending_spinlock);
+ list_for_each_entry(pe2, &pending_all, list_all) {
+ BUG_ON(pe2 == pe);
+ }
+ list_add(&pe->list_all, &pending_all);
+ spin_unlock(&pending_spinlock);
+
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
+
return pe;
}
static void free_pending_exception(struct dm_snap_pending_exception *pe)
{
struct dm_snapshot *s = pe->snap;
+ struct dm_snap_pending_exception *pe2;
+
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
+
+ spin_lock(&pending_spinlock);
+ list_for_each_entry(pe2, &pending_all, list_all) {
+ if (pe2 == pe) goto found;
+ }
+ BUG();
+ found:
+ list_del(&pe->list_all);
+ spin_unlock(&pending_spinlock);
mempool_free(pe, s->pending_pool);
smp_mb__before_atomic_dec();
@@ -831,6 +858,8 @@ static struct bio *put_pending_exception
struct dm_snap_pending_exception *primary_pe;
struct bio *origin_bios = NULL;
+ pe->snap->store.check_pending_exception(&pe->snap->store, pe, __LINE__);
+
primary_pe = pe->primary_pe;
/*
@@ -862,12 +891,15 @@ static void pending_complete(struct dm_s
struct bio *snapshot_bios = NULL;
int error = 0;
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
+
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
if (!success) {
/* Read/write error - snapshot is unusable */
down_write(&s->lock);
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
__invalidate_snapshot(s, -EIO);
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
@@ -885,6 +917,7 @@ static void pending_complete(struct dm_s
if (!e) {
down_write(&s->lock);
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
__invalidate_snapshot(s, -ENOMEM);
error = 1;
goto out;
@@ -892,6 +925,7 @@ static void pending_complete(struct dm_s
*e = pe->e;
down_write(&s->lock);
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
@@ -943,6 +977,7 @@ static void commit_callback(void *contex
{
struct dm_snap_pending_exception *pe = context;
+ pe->snap->store.check_pending_exception(&pe->snap->store, pe, __LINE__);
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
@@ -961,13 +996,15 @@ static void copy_callback(int read_err,
BUG_ON(pe->e.hash_list.next == LIST_POISON1);
BUG_ON(pe->e.hash_list.prev == LIST_POISON2);
- if (read_err || write_err)
+ if (read_err || write_err) {
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
pending_complete(pe, 0);
-
- else
+ } else {
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
/* Update the metadata if we are persistent */
s->store.commit_exception(&s->store, &pe->e, commit_callback,
pe);
+ }
}
/*
@@ -979,6 +1016,7 @@ static void start_copy(struct dm_snap_pe
struct dm_io_region src, dest;
struct block_device *bdev = s->origin->bdev;
sector_t dev_size;
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
BUG_ON(!pe->started);
BUG_ON(pe->started == 2);
BUG_ON(pe->started != 1);
@@ -1038,6 +1076,7 @@ __find_pending_exception(struct dm_snaps
up_write(&s->lock);
pe = alloc_pending_exception(s);
down_write(&s->lock);
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
if (!s->valid) {
free_pending_exception(pe);
@@ -1071,6 +1110,7 @@ __find_pending_exception(struct dm_snaps
get_pending_exception(pe);
insert_exception(&s->pending, &pe->e);
+ s->store.check_pending_exception(&s->store, pe, __LINE__);
out:
return pe;
@@ -1291,6 +1331,7 @@ static int __origin_write(struct list_he
}
if (!pe->started) {
+ snap->store.check_pending_exception(&snap->store, pe, __LINE__);
pe->started = 1;
list_add_tail(&pe->list, &pe_queue);
}
@@ -1319,8 +1360,10 @@ static int __origin_write(struct list_he
/*
* Now that we have a complete pe list we can start the copying.
*/
- list_for_each_entry_safe(pe, next_pe, &pe_queue, list)
+ list_for_each_entry_safe(pe, next_pe, &pe_queue, list) {
+ pe->snap->store.check_pending_exception(&pe->snap->store, pe, __LINE__);
start_copy(pe);
+ }
return r;
}
--
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