v4.19.13 snapshot.
diff --git a/drivers/md/persistent-data/dm-block-manager.c b/drivers/md/persistent-data/dm-block-manager.c
new file mode 100644
index 0000000..492a3f8
--- /dev/null
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -0,0 +1,648 @@
+/*
+ * Copyright (C) 2011 Red Hat, Inc.
+ *
+ * This file is released under the GPL.
+ */
+#include "dm-block-manager.h"
+#include "dm-persistent-data-internal.h"
+
+#include <linux/dm-bufio.h>
+#include <linux/crc32c.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/rwsem.h>
+#include <linux/device-mapper.h>
+#include <linux/stacktrace.h>
+#include <linux/sched/task.h>
+
+#define DM_MSG_PREFIX "block manager"
+
+/*----------------------------------------------------------------*/
+
+#ifdef CONFIG_DM_DEBUG_BLOCK_MANAGER_LOCKING
+
+/*
+ * This is a read/write semaphore with a couple of differences.
+ *
+ * i) There is a restriction on the number of concurrent read locks that
+ * may be held at once. This is just an implementation detail.
+ *
+ * ii) Recursive locking attempts are detected and return EINVAL. A stack
+ * trace is also emitted for the previous lock acquisition.
+ *
+ * iii) Priority is given to write locks.
+ */
+#define MAX_HOLDERS 4
+#define MAX_STACK 10
+
+typedef unsigned long stack_entries[MAX_STACK];
+
+struct block_lock {
+ spinlock_t lock;
+ __s32 count;
+ struct list_head waiters;
+ struct task_struct *holders[MAX_HOLDERS];
+
+#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
+ struct stack_trace traces[MAX_HOLDERS];
+ stack_entries entries[MAX_HOLDERS];
+#endif
+};
+
+struct waiter {
+ struct list_head list;
+ struct task_struct *task;
+ int wants_write;
+};
+
+static unsigned __find_holder(struct block_lock *lock,
+ struct task_struct *task)
+{
+ unsigned i;
+
+ for (i = 0; i < MAX_HOLDERS; i++)
+ if (lock->holders[i] == task)
+ break;
+
+ BUG_ON(i == MAX_HOLDERS);
+ return i;
+}
+
+/* call this *after* you increment lock->count */
+static void __add_holder(struct block_lock *lock, struct task_struct *task)
+{
+ unsigned h = __find_holder(lock, NULL);
+#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
+ struct stack_trace *t;
+#endif
+
+ get_task_struct(task);
+ lock->holders[h] = task;
+
+#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
+ t = lock->traces + h;
+ t->nr_entries = 0;
+ t->max_entries = MAX_STACK;
+ t->entries = lock->entries[h];
+ t->skip = 2;
+ save_stack_trace(t);
+#endif
+}
+
+/* call this *before* you decrement lock->count */
+static void __del_holder(struct block_lock *lock, struct task_struct *task)
+{
+ unsigned h = __find_holder(lock, task);
+ lock->holders[h] = NULL;
+ put_task_struct(task);
+}
+
+static int __check_holder(struct block_lock *lock)
+{
+ unsigned i;
+
+ for (i = 0; i < MAX_HOLDERS; i++) {
+ if (lock->holders[i] == current) {
+ DMERR("recursive lock detected in metadata");
+#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
+ DMERR("previously held here:");
+ print_stack_trace(lock->traces + i, 4);
+
+ DMERR("subsequent acquisition attempted here:");
+ dump_stack();
+#endif
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+static void __wait(struct waiter *w)
+{
+ for (;;) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+
+ if (!w->task)
+ break;
+
+ schedule();
+ }
+
+ set_current_state(TASK_RUNNING);
+}
+
+static void __wake_waiter(struct waiter *w)
+{
+ struct task_struct *task;
+
+ list_del(&w->list);
+ task = w->task;
+ smp_mb();
+ w->task = NULL;
+ wake_up_process(task);
+}
+
+/*
+ * We either wake a few readers or a single writer.
+ */
+static void __wake_many(struct block_lock *lock)
+{
+ struct waiter *w, *tmp;
+
+ BUG_ON(lock->count < 0);
+ list_for_each_entry_safe(w, tmp, &lock->waiters, list) {
+ if (lock->count >= MAX_HOLDERS)
+ return;
+
+ if (w->wants_write) {
+ if (lock->count > 0)
+ return; /* still read locked */
+
+ lock->count = -1;
+ __add_holder(lock, w->task);
+ __wake_waiter(w);
+ return;
+ }
+
+ lock->count++;
+ __add_holder(lock, w->task);
+ __wake_waiter(w);
+ }
+}
+
+static void bl_init(struct block_lock *lock)
+{
+ int i;
+
+ spin_lock_init(&lock->lock);
+ lock->count = 0;
+ INIT_LIST_HEAD(&lock->waiters);
+ for (i = 0; i < MAX_HOLDERS; i++)
+ lock->holders[i] = NULL;
+}
+
+static int __available_for_read(struct block_lock *lock)
+{
+ return lock->count >= 0 &&
+ lock->count < MAX_HOLDERS &&
+ list_empty(&lock->waiters);
+}
+
+static int bl_down_read(struct block_lock *lock)
+{
+ int r;
+ struct waiter w;
+
+ spin_lock(&lock->lock);
+ r = __check_holder(lock);
+ if (r) {
+ spin_unlock(&lock->lock);
+ return r;
+ }
+
+ if (__available_for_read(lock)) {
+ lock->count++;
+ __add_holder(lock, current);
+ spin_unlock(&lock->lock);
+ return 0;
+ }
+
+ get_task_struct(current);
+
+ w.task = current;
+ w.wants_write = 0;
+ list_add_tail(&w.list, &lock->waiters);
+ spin_unlock(&lock->lock);
+
+ __wait(&w);
+ put_task_struct(current);
+ return 0;
+}
+
+static int bl_down_read_nonblock(struct block_lock *lock)
+{
+ int r;
+
+ spin_lock(&lock->lock);
+ r = __check_holder(lock);
+ if (r)
+ goto out;
+
+ if (__available_for_read(lock)) {
+ lock->count++;
+ __add_holder(lock, current);
+ r = 0;
+ } else
+ r = -EWOULDBLOCK;
+
+out:
+ spin_unlock(&lock->lock);
+ return r;
+}
+
+static void bl_up_read(struct block_lock *lock)
+{
+ spin_lock(&lock->lock);
+ BUG_ON(lock->count <= 0);
+ __del_holder(lock, current);
+ --lock->count;
+ if (!list_empty(&lock->waiters))
+ __wake_many(lock);
+ spin_unlock(&lock->lock);
+}
+
+static int bl_down_write(struct block_lock *lock)
+{
+ int r;
+ struct waiter w;
+
+ spin_lock(&lock->lock);
+ r = __check_holder(lock);
+ if (r) {
+ spin_unlock(&lock->lock);
+ return r;
+ }
+
+ if (lock->count == 0 && list_empty(&lock->waiters)) {
+ lock->count = -1;
+ __add_holder(lock, current);
+ spin_unlock(&lock->lock);
+ return 0;
+ }
+
+ get_task_struct(current);
+ w.task = current;
+ w.wants_write = 1;
+
+ /*
+ * Writers given priority. We know there's only one mutator in the
+ * system, so ignoring the ordering reversal.
+ */
+ list_add(&w.list, &lock->waiters);
+ spin_unlock(&lock->lock);
+
+ __wait(&w);
+ put_task_struct(current);
+
+ return 0;
+}
+
+static void bl_up_write(struct block_lock *lock)
+{
+ spin_lock(&lock->lock);
+ __del_holder(lock, current);
+ lock->count = 0;
+ if (!list_empty(&lock->waiters))
+ __wake_many(lock);
+ spin_unlock(&lock->lock);
+}
+
+static void report_recursive_bug(dm_block_t b, int r)
+{
+ if (r == -EINVAL)
+ DMERR("recursive acquisition of block %llu requested.",
+ (unsigned long long) b);
+}
+
+#else /* !CONFIG_DM_DEBUG_BLOCK_MANAGER_LOCKING */
+
+#define bl_init(x) do { } while (0)
+#define bl_down_read(x) 0
+#define bl_down_read_nonblock(x) 0
+#define bl_up_read(x) do { } while (0)
+#define bl_down_write(x) 0
+#define bl_up_write(x) do { } while (0)
+#define report_recursive_bug(x, y) do { } while (0)
+
+#endif /* CONFIG_DM_DEBUG_BLOCK_MANAGER_LOCKING */
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Block manager is currently implemented using dm-bufio. struct
+ * dm_block_manager and struct dm_block map directly onto a couple of
+ * structs in the bufio interface. I want to retain the freedom to move
+ * away from bufio in the future. So these structs are just cast within
+ * this .c file, rather than making it through to the public interface.
+ */
+static struct dm_buffer *to_buffer(struct dm_block *b)
+{
+ return (struct dm_buffer *) b;
+}
+
+dm_block_t dm_block_location(struct dm_block *b)
+{
+ return dm_bufio_get_block_number(to_buffer(b));
+}
+EXPORT_SYMBOL_GPL(dm_block_location);
+
+void *dm_block_data(struct dm_block *b)
+{
+ return dm_bufio_get_block_data(to_buffer(b));
+}
+EXPORT_SYMBOL_GPL(dm_block_data);
+
+struct buffer_aux {
+ struct dm_block_validator *validator;
+ int write_locked;
+
+#ifdef CONFIG_DM_DEBUG_BLOCK_MANAGER_LOCKING
+ struct block_lock lock;
+#endif
+};
+
+static void dm_block_manager_alloc_callback(struct dm_buffer *buf)
+{
+ struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
+ aux->validator = NULL;
+ bl_init(&aux->lock);
+}
+
+static void dm_block_manager_write_callback(struct dm_buffer *buf)
+{
+ struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
+ if (aux->validator) {
+ aux->validator->prepare_for_write(aux->validator, (struct dm_block *) buf,
+ dm_bufio_get_block_size(dm_bufio_get_client(buf)));
+ }
+}
+
+/*----------------------------------------------------------------
+ * Public interface
+ *--------------------------------------------------------------*/
+struct dm_block_manager {
+ struct dm_bufio_client *bufio;
+ bool read_only:1;
+};
+
+struct dm_block_manager *dm_block_manager_create(struct block_device *bdev,
+ unsigned block_size,
+ unsigned max_held_per_thread)
+{
+ int r;
+ struct dm_block_manager *bm;
+
+ bm = kmalloc(sizeof(*bm), GFP_KERNEL);
+ if (!bm) {
+ r = -ENOMEM;
+ goto bad;
+ }
+
+ bm->bufio = dm_bufio_client_create(bdev, block_size, max_held_per_thread,
+ sizeof(struct buffer_aux),
+ dm_block_manager_alloc_callback,
+ dm_block_manager_write_callback);
+ if (IS_ERR(bm->bufio)) {
+ r = PTR_ERR(bm->bufio);
+ kfree(bm);
+ goto bad;
+ }
+
+ bm->read_only = false;
+
+ return bm;
+
+bad:
+ return ERR_PTR(r);
+}
+EXPORT_SYMBOL_GPL(dm_block_manager_create);
+
+void dm_block_manager_destroy(struct dm_block_manager *bm)
+{
+ dm_bufio_client_destroy(bm->bufio);
+ kfree(bm);
+}
+EXPORT_SYMBOL_GPL(dm_block_manager_destroy);
+
+unsigned dm_bm_block_size(struct dm_block_manager *bm)
+{
+ return dm_bufio_get_block_size(bm->bufio);
+}
+EXPORT_SYMBOL_GPL(dm_bm_block_size);
+
+dm_block_t dm_bm_nr_blocks(struct dm_block_manager *bm)
+{
+ return dm_bufio_get_device_size(bm->bufio);
+}
+
+static int dm_bm_validate_buffer(struct dm_block_manager *bm,
+ struct dm_buffer *buf,
+ struct buffer_aux *aux,
+ struct dm_block_validator *v)
+{
+ if (unlikely(!aux->validator)) {
+ int r;
+ if (!v)
+ return 0;
+ r = v->check(v, (struct dm_block *) buf, dm_bufio_get_block_size(bm->bufio));
+ if (unlikely(r)) {
+ DMERR_LIMIT("%s validator check failed for block %llu", v->name,
+ (unsigned long long) dm_bufio_get_block_number(buf));
+ return r;
+ }
+ aux->validator = v;
+ } else {
+ if (unlikely(aux->validator != v)) {
+ DMERR_LIMIT("validator mismatch (old=%s vs new=%s) for block %llu",
+ aux->validator->name, v ? v->name : "NULL",
+ (unsigned long long) dm_bufio_get_block_number(buf));
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+int dm_bm_read_lock(struct dm_block_manager *bm, dm_block_t b,
+ struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ struct buffer_aux *aux;
+ void *p;
+ int r;
+
+ p = dm_bufio_read(bm->bufio, b, (struct dm_buffer **) result);
+ if (unlikely(IS_ERR(p)))
+ return PTR_ERR(p);
+
+ aux = dm_bufio_get_aux_data(to_buffer(*result));
+ r = bl_down_read(&aux->lock);
+ if (unlikely(r)) {
+ dm_bufio_release(to_buffer(*result));
+ report_recursive_bug(b, r);
+ return r;
+ }
+
+ aux->write_locked = 0;
+
+ r = dm_bm_validate_buffer(bm, to_buffer(*result), aux, v);
+ if (unlikely(r)) {
+ bl_up_read(&aux->lock);
+ dm_bufio_release(to_buffer(*result));
+ return r;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dm_bm_read_lock);
+
+int dm_bm_write_lock(struct dm_block_manager *bm,
+ dm_block_t b, struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ struct buffer_aux *aux;
+ void *p;
+ int r;
+
+ if (bm->read_only)
+ return -EPERM;
+
+ p = dm_bufio_read(bm->bufio, b, (struct dm_buffer **) result);
+ if (unlikely(IS_ERR(p)))
+ return PTR_ERR(p);
+
+ aux = dm_bufio_get_aux_data(to_buffer(*result));
+ r = bl_down_write(&aux->lock);
+ if (r) {
+ dm_bufio_release(to_buffer(*result));
+ report_recursive_bug(b, r);
+ return r;
+ }
+
+ aux->write_locked = 1;
+
+ r = dm_bm_validate_buffer(bm, to_buffer(*result), aux, v);
+ if (unlikely(r)) {
+ bl_up_write(&aux->lock);
+ dm_bufio_release(to_buffer(*result));
+ return r;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dm_bm_write_lock);
+
+int dm_bm_read_try_lock(struct dm_block_manager *bm,
+ dm_block_t b, struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ struct buffer_aux *aux;
+ void *p;
+ int r;
+
+ p = dm_bufio_get(bm->bufio, b, (struct dm_buffer **) result);
+ if (unlikely(IS_ERR(p)))
+ return PTR_ERR(p);
+ if (unlikely(!p))
+ return -EWOULDBLOCK;
+
+ aux = dm_bufio_get_aux_data(to_buffer(*result));
+ r = bl_down_read_nonblock(&aux->lock);
+ if (r < 0) {
+ dm_bufio_release(to_buffer(*result));
+ report_recursive_bug(b, r);
+ return r;
+ }
+ aux->write_locked = 0;
+
+ r = dm_bm_validate_buffer(bm, to_buffer(*result), aux, v);
+ if (unlikely(r)) {
+ bl_up_read(&aux->lock);
+ dm_bufio_release(to_buffer(*result));
+ return r;
+ }
+
+ return 0;
+}
+
+int dm_bm_write_lock_zero(struct dm_block_manager *bm,
+ dm_block_t b, struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ int r;
+ struct buffer_aux *aux;
+ void *p;
+
+ if (bm->read_only)
+ return -EPERM;
+
+ p = dm_bufio_new(bm->bufio, b, (struct dm_buffer **) result);
+ if (unlikely(IS_ERR(p)))
+ return PTR_ERR(p);
+
+ memset(p, 0, dm_bm_block_size(bm));
+
+ aux = dm_bufio_get_aux_data(to_buffer(*result));
+ r = bl_down_write(&aux->lock);
+ if (r) {
+ dm_bufio_release(to_buffer(*result));
+ return r;
+ }
+
+ aux->write_locked = 1;
+ aux->validator = v;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dm_bm_write_lock_zero);
+
+void dm_bm_unlock(struct dm_block *b)
+{
+ struct buffer_aux *aux;
+ aux = dm_bufio_get_aux_data(to_buffer(b));
+
+ if (aux->write_locked) {
+ dm_bufio_mark_buffer_dirty(to_buffer(b));
+ bl_up_write(&aux->lock);
+ } else
+ bl_up_read(&aux->lock);
+
+ dm_bufio_release(to_buffer(b));
+}
+EXPORT_SYMBOL_GPL(dm_bm_unlock);
+
+int dm_bm_flush(struct dm_block_manager *bm)
+{
+ if (bm->read_only)
+ return -EPERM;
+
+ return dm_bufio_write_dirty_buffers(bm->bufio);
+}
+EXPORT_SYMBOL_GPL(dm_bm_flush);
+
+void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b)
+{
+ dm_bufio_prefetch(bm->bufio, b, 1);
+}
+
+bool dm_bm_is_read_only(struct dm_block_manager *bm)
+{
+ return bm->read_only;
+}
+EXPORT_SYMBOL_GPL(dm_bm_is_read_only);
+
+void dm_bm_set_read_only(struct dm_block_manager *bm)
+{
+ bm->read_only = true;
+}
+EXPORT_SYMBOL_GPL(dm_bm_set_read_only);
+
+void dm_bm_set_read_write(struct dm_block_manager *bm)
+{
+ bm->read_only = false;
+}
+EXPORT_SYMBOL_GPL(dm_bm_set_read_write);
+
+u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor)
+{
+ return crc32c(~(u32) 0, data, len) ^ init_xor;
+}
+EXPORT_SYMBOL_GPL(dm_bm_checksum);
+
+/*----------------------------------------------------------------*/
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
+MODULE_DESCRIPTION("Immutable metadata library for dm");
+
+/*----------------------------------------------------------------*/