Hi
Here I'm sending two dm-bufio patches. The first one fixed
dm_bufio_release_move function (the write callback could be called with a
wrong block number). The next one adds a conditional resched (Alasdair
agreed on it --- it should be later put into general Linux headers).
Mikulas
---
drivers/md/dm-bufio.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
Index: linux-3.1-rc3-fast/drivers/md/dm-bufio.c
===================================================================
--- linux-3.1-rc3-fast.orig/drivers/md/dm-bufio.c 2011-10-19 18:39:22.000000000 +0200
+++ linux-3.1-rc3-fast/drivers/md/dm-bufio.c 2011-10-19 18:47:43.000000000 +0200
@@ -1185,11 +1185,24 @@ retry:
__unlink_buffer(b);
__link_buffer(b, new_block, LIST_DIRTY);
} else {
+ sector_t old_block;
wait_on_bit_lock(&b->state, B_WRITING,
do_io_schedule, TASK_UNINTERRUPTIBLE);
+ /*
+ * Relink buffer to "new_block" so that write_callback
+ * sees "new_block" as a block number.
+ * After the write, link the buffer back to old_block.
+ * All this must be done in bufio lock, so that block number
+ * change isn't visible to other threads.
+ */
+ old_block = b->block;
+ __unlink_buffer(b);
+ __link_buffer(b, new_block, b->list_mode);
submit_io(b, WRITE, new_block, write_endio);
wait_on_bit(&b->state, B_WRITING,
do_io_schedule, TASK_UNINTERRUPTIBLE);
+ __unlink_buffer(b);
+ __link_buffer(b, old_block, b->list_mode);
}
dm_bufio_unlock(c);
---
drivers/md/dm-bufio.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
Index: linux-3.1-rc3-fast/drivers/md/dm-bufio.c
===================================================================
--- linux-3.1-rc3-fast.orig/drivers/md/dm-bufio.c 2011-10-19 18:49:14.000000000 +0200
+++ linux-3.1-rc3-fast/drivers/md/dm-bufio.c 2011-10-19 18:57:01.000000000 +0200
@@ -183,6 +183,16 @@ static void dm_bufio_unlock(struct dm_bu
mutex_unlock(&c->lock);
}
+#ifdef CONFIG_PREEMPT_VOLUNTARY
+#define dm_bufio_cond_resched() \
+do { \
+ if (unlikely(need_resched())) \
+ _cond_resched(); \
+} while (0)
+#else
+#define dm_bufio_cond_resched() do { } while (0)
+#endif
+
/*----------------------------------------------------------------*/
/*
@@ -644,6 +654,7 @@ static struct dm_buffer *__get_unclaimed
__unlink_buffer(b);
return b;
}
+ dm_bufio_cond_resched();
}
list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) {
@@ -654,6 +665,7 @@ static struct dm_buffer *__get_unclaimed
__unlink_buffer(b);
return b;
}
+ dm_bufio_cond_resched();
}
return NULL;
@@ -772,6 +784,7 @@ static void __write_dirty_buffers_async(
return;
__write_dirty_buffer(b);
+ dm_bufio_cond_resched();
}
}
@@ -820,6 +833,7 @@ static void __check_watermark(struct dm_
return;
__free_buffer_wake(b);
+ dm_bufio_cond_resched();
}
if (c->n_buffers[LIST_DIRTY] > threshold_buffers)
@@ -835,9 +849,11 @@ static struct dm_buffer *__find(struct d
struct hlist_node *hn;
hlist_for_each_entry(b, hn, &c->cache_hash[DM_BUFIO_HASH(block)],
- hash_list)
+ hash_list) {
+ dm_bufio_cond_resched();
if (b->block == block)
return b;
+ }
return NULL;
}
@@ -1084,6 +1100,8 @@ again:
!test_bit(B_WRITING, &b->state))
__relink_lru(b, LIST_CLEAN);
+ dm_bufio_cond_resched();
+
/*
* If we dropped the lock, the list is no longer consistent,
* so we must restart the search.
@@ -1310,11 +1328,13 @@ static void __scan(struct dm_bufio_clien
int l;
struct dm_buffer *b, *tmp;
- for (l = 0; l < LIST_SIZE; l++)
+ for (l = 0; l < LIST_SIZE; l++) {
list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list)
if (!__cleanup_old_buffer(b, sc->gfp_mask, 0) &&
!--nr_to_scan)
return;
+ dm_bufio_cond_resched();
+ }
}
static int shrink(struct shrinker *shrinker, struct shrink_control *sc)
@@ -1531,9 +1551,11 @@ static void cleanup_old_buffers(void)
struct dm_buffer, lru_list);
if (__cleanup_old_buffer(b, 0, max_age * HZ))
break;
+ dm_bufio_cond_resched();
}
dm_bufio_unlock(c);
+ dm_bufio_cond_resched();
}
mutex_unlock(&dm_bufio_clients_lock);
}
--
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