#include <linux/init.h>
#include <linux/kdev_t.h>
#include <linux/list.h>
+#include <linux/list_bl.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/slab.h>
struct dm_exception_table {
uint32_t hash_mask;
unsigned hash_shift;
- struct list_head *table;
+ struct hlist_bl_head *table;
};
struct dm_snapshot {
* The lowest hash_shift bits of the chunk number are ignored, allowing
* some consecutive chunks to be grouped together.
*/
+static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk);
+
+/* Lock to protect access to the completed and pending exception hash tables. */
+struct dm_exception_table_lock {
+ struct hlist_bl_head *complete_slot;
+ struct hlist_bl_head *pending_slot;
+};
+
+static void dm_exception_table_lock_init(struct dm_snapshot *s, chunk_t chunk,
+ struct dm_exception_table_lock *lock)
+{
+ struct dm_exception_table *complete = &s->complete;
+ struct dm_exception_table *pending = &s->pending;
+
+ lock->complete_slot = &complete->table[exception_hash(complete, chunk)];
+ lock->pending_slot = &pending->table[exception_hash(pending, chunk)];
+}
+
+static void dm_exception_table_lock(struct dm_exception_table_lock *lock)
+{
+ hlist_bl_lock(lock->complete_slot);
+ hlist_bl_lock(lock->pending_slot);
+}
+
+static void dm_exception_table_unlock(struct dm_exception_table_lock *lock)
+{
+ hlist_bl_unlock(lock->pending_slot);
+ hlist_bl_unlock(lock->complete_slot);
+}
+
static int dm_exception_table_init(struct dm_exception_table *et,
uint32_t size, unsigned hash_shift)
{
et->hash_shift = hash_shift;
et->hash_mask = size - 1;
- et->table = dm_vcalloc(size, sizeof(struct list_head));
+ et->table = dm_vcalloc(size, sizeof(struct hlist_bl_head));
if (!et->table)
return -ENOMEM;
for (i = 0; i < size; i++)
- INIT_LIST_HEAD(et->table + i);
+ INIT_HLIST_BL_HEAD(et->table + i);
return 0;
}
static void dm_exception_table_exit(struct dm_exception_table *et,
struct kmem_cache *mem)
{
- struct list_head *slot;
- struct dm_exception *ex, *next;
+ struct hlist_bl_head *slot;
+ struct dm_exception *ex;
+ struct hlist_bl_node *pos, *n;
int i, size;
size = et->hash_mask + 1;
for (i = 0; i < size; i++) {
slot = et->table + i;
- list_for_each_entry_safe (ex, next, slot, hash_list)
+ hlist_bl_for_each_entry_safe(ex, pos, n, slot, hash_list)
kmem_cache_free(mem, ex);
}
static void dm_remove_exception(struct dm_exception *e)
{
- list_del(&e->hash_list);
+ hlist_bl_del(&e->hash_list);
}
/*
static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et,
chunk_t chunk)
{
- struct list_head *slot;
+ struct hlist_bl_head *slot;
+ struct hlist_bl_node *pos;
struct dm_exception *e;
slot = &et->table[exception_hash(et, chunk)];
- list_for_each_entry (e, slot, hash_list)
+ hlist_bl_for_each_entry(e, pos, slot, hash_list)
if (chunk >= e->old_chunk &&
chunk <= e->old_chunk + dm_consecutive_chunk_count(e))
return e;
static void dm_insert_exception(struct dm_exception_table *eh,
struct dm_exception *new_e)
{
- struct list_head *l;
+ struct hlist_bl_head *l;
+ struct hlist_bl_node *pos;
struct dm_exception *e = NULL;
l = &eh->table[exception_hash(eh, new_e->old_chunk)];
goto out;
/* List is ordered by old_chunk */
- list_for_each_entry_reverse(e, l, hash_list) {
+ hlist_bl_for_each_entry(e, pos, l, hash_list) {
/* Insert after an existing chunk? */
if (new_e->old_chunk == (e->old_chunk +
dm_consecutive_chunk_count(e) + 1) &&
return;
}
- if (new_e->old_chunk > e->old_chunk)
+ if (new_e->old_chunk < e->old_chunk)
break;
}
out:
- list_add(&new_e->hash_list, e ? &e->hash_list : l);
+ if (!e) {
+ /*
+ * Either the table doesn't support consecutive chunks or slot
+ * l is empty.
+ */
+ hlist_bl_add_head(&new_e->hash_list, l);
+ } else if (new_e->old_chunk < e->old_chunk) {
+ /* Add before an existing exception */
+ hlist_bl_add_before(&new_e->hash_list, &e->hash_list);
+ } else {
+ /* Add to l's tail: e is the last exception in this slot */
+ hlist_bl_add_behind(&new_e->hash_list, &e->hash_list);
+ }
}
/*
*/
static int dm_add_exception(void *context, chunk_t old, chunk_t new)
{
+ struct dm_exception_table_lock lock;
struct dm_snapshot *s = context;
struct dm_exception *e;
/* Consecutive_count is implicitly initialised to zero */
e->new_chunk = new;
+ /*
+ * Although there is no need to lock access to the exception tables
+ * here, if we don't then hlist_bl_add_head(), called by
+ * dm_insert_exception(), will complain about accessing the
+ * corresponding list without locking it first.
+ */
+ dm_exception_table_lock_init(s, old, &lock);
+
+ dm_exception_table_lock(&lock);
dm_insert_exception(&s->complete, e);
+ dm_exception_table_unlock(&lock);
return 0;
}
{
/* use a fixed size of 2MB */
unsigned long mem = 2 * 1024 * 1024;
- mem /= sizeof(struct list_head);
+ mem /= sizeof(struct hlist_bl_head);
return mem;
}
struct bio *origin_bios = NULL;
struct bio *snapshot_bios = NULL;
struct bio *full_bio = NULL;
+ struct dm_exception_table_lock lock;
int error = 0;
+ dm_exception_table_lock_init(s, pe->e.old_chunk, &lock);
+
if (!success) {
/* Read/write error - snapshot is unusable */
down_write(&s->lock);
__invalidate_snapshot(s, -EIO);
error = 1;
+
+ dm_exception_table_lock(&lock);
goto out;
}
down_write(&s->lock);
__invalidate_snapshot(s, -ENOMEM);
error = 1;
+
+ dm_exception_table_lock(&lock);
goto out;
}
*e = pe->e;
down_write(&s->lock);
+ dm_exception_table_lock(&lock);
if (!s->valid) {
free_completed_exception(e);
error = 1;
/* Wait for conflicting reads to drain */
if (__chunk_is_tracked(s, pe->e.old_chunk)) {
+ dm_exception_table_unlock(&lock);
up_write(&s->lock);
__check_for_conflicting_io(s, pe->e.old_chunk);
down_write(&s->lock);
+ dm_exception_table_lock(&lock);
}
out:
/* Remove the in-flight exception from the list */
dm_remove_exception(&pe->e);
+
+ dm_exception_table_unlock(&lock);
+
snapshot_bios = bio_list_get(&pe->snapshot_bios);
origin_bios = bio_list_get(&pe->origin_bios);
full_bio = pe->full_bio;
int r = DM_MAPIO_REMAPPED;
chunk_t chunk;
struct dm_snap_pending_exception *pe = NULL;
+ struct dm_exception_table_lock lock;
init_tracked_chunk(bio);
}
chunk = sector_to_chunk(s->store, bio->bi_iter.bi_sector);
+ dm_exception_table_lock_init(s, chunk, &lock);
/* Full snapshots are not usable */
/* To get here the table must be live so s->active is always set. */
return DM_MAPIO_KILL;
down_write(&s->lock);
+ dm_exception_table_lock(&lock);
if (!s->valid || (unlikely(s->snapshot_overflowed) &&
bio_data_dir(bio) == WRITE)) {
if (bio_data_dir(bio) == WRITE) {
pe = __lookup_pending_exception(s, chunk);
if (!pe) {
+ dm_exception_table_unlock(&lock);
up_write(&s->lock);
pe = alloc_pending_exception(s);
down_write(&s->lock);
+ dm_exception_table_lock(&lock);
if (!s->valid || s->snapshot_overflowed) {
free_pending_exception(pe);
pe = __find_pending_exception(s, pe, chunk);
if (!pe) {
+ dm_exception_table_unlock(&lock);
+
if (s->store->userspace_supports_overflow) {
s->snapshot_overflowed = 1;
DMERR("Snapshot overflowed: Unable to allocate exception.");
} else
__invalidate_snapshot(s, -ENOMEM);
+ up_write(&s->lock);
+
r = DM_MAPIO_KILL;
- goto out_unlock;
+ goto out;
}
}
bio->bi_iter.bi_size ==
(s->store->chunk_size << SECTOR_SHIFT)) {
pe->started = 1;
+ dm_exception_table_unlock(&lock);
up_write(&s->lock);
start_full_bio(pe, bio);
goto out;
if (!pe->started) {
/* this is protected by snap->lock */
pe->started = 1;
+ dm_exception_table_unlock(&lock);
up_write(&s->lock);
start_copy(pe);
goto out;
}
out_unlock:
+ dm_exception_table_unlock(&lock);
up_write(&s->lock);
out:
return r;
struct dm_snap_pending_exception *pe, *pe2;
struct dm_snap_pending_exception *pe_to_start_now = NULL;
struct dm_snap_pending_exception *pe_to_start_last = NULL;
+ struct dm_exception_table_lock lock;
chunk_t chunk;
/* Do all the snapshots on this origin */
if (dm_target_is_snapshot_merge(snap->ti))
continue;
- down_write(&snap->lock);
-
- /* Only deal with valid and active snapshots */
- if (!snap->valid || !snap->active)
- goto next_snapshot;
-
/* Nothing to do if writing beyond end of snapshot */
if (sector >= dm_table_get_size(snap->ti->table))
- goto next_snapshot;
+ continue;
/*
* Remember, different snapshots can have
* different chunk sizes.
*/
chunk = sector_to_chunk(snap->store, sector);
+ dm_exception_table_lock_init(snap, chunk, &lock);
+
+ down_write(&snap->lock);
+ dm_exception_table_lock(&lock);
+
+ /* Only deal with valid and active snapshots */
+ if (!snap->valid || !snap->active)
+ goto next_snapshot;
pe = __lookup_pending_exception(snap, chunk);
if (!pe) {
if (e)
goto next_snapshot;
+ dm_exception_table_unlock(&lock);
up_write(&snap->lock);
pe = alloc_pending_exception(snap);
down_write(&snap->lock);
+ dm_exception_table_lock(&lock);
if (!snap->valid) {
free_pending_exception(pe);
pe = __insert_pending_exception(snap, pe, chunk);
if (!pe) {
+ dm_exception_table_unlock(&lock);
__invalidate_snapshot(snap, -ENOMEM);
- goto next_snapshot;
+ up_write(&snap->lock);
+
+ continue;
}
} else {
free_pending_exception(pe);
}
next_snapshot:
+ dm_exception_table_unlock(&lock);
up_write(&snap->lock);
if (pe_to_start_now) {
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