1 files changed, 123 insertions, 69 deletions

diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 2129cdb115d..d6e88178d22 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -10,12 +10,16 @@
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 #include <linux/vmalloc.h>
+#include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/dm-io.h>
+#include "dm-bufio.h"
 
 #define DM_MSG_PREFIX "persistent snapshot"
 #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32	/* 16KB */
 
+#define DM_PREFETCH_CHUNKS		12
+
 /*-----------------------------------------------------------------
  * Persistent snapshots, by persistent we mean that the snapshot
  * will survive a reboot.
@@ -58,25 +62,30 @@
 #define NUM_SNAPSHOT_HDR_CHUNKS 1
 
 struct disk_header {
-	uint32_t magic;
+	__le32 magic;
 
 	/*
 	 * Is this snapshot valid.  There is no way of recovering
 	 * an invalid snapshot.
 	 */
-	uint32_t valid;
+	__le32 valid;
 
 	/*
 	 * Simple, incrementing version. no backward
 	 * compatibility.
 	 */
-	uint32_t version;
+	__le32 version;
 
 	/* In sectors */
-	uint32_t chunk_size;
-};
+	__le32 chunk_size;
+} __packed;
 
 struct disk_exception {
+	__le64 old_chunk;
+	__le64 new_chunk;
+} __packed;
+
+struct core_exception {
 	uint64_t old_chunk;
 	uint64_t new_chunk;
 };
@@ -154,11 +163,6 @@ struct pstore {
 	struct workqueue_struct *metadata_wq;
 };
 
-static unsigned sectors_to_pages(unsigned sectors)
-{
-	return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9);
-}
-
 static int alloc_area(struct pstore *ps)
 {
 	int r = -ENOMEM;
@@ -174,10 +178,9 @@ static int alloc_area(struct pstore *ps)
 	if (!ps->area)
 		goto err_area;
 
-	ps->zero_area = vmalloc(len);
+	ps->zero_area = vzalloc(len);
 	if (!ps->zero_area)
 		goto err_zero_area;
-	memset(ps->zero_area, 0, len);
 
 	ps->header_area = vmalloc(len);
 	if (!ps->header_area)
@@ -257,6 +260,7 @@ static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw,
 	INIT_WORK_ONSTACK(&req.work, do_metadata);
 	queue_work(ps->metadata_wq, &req.work);
 	flush_workqueue(ps->metadata_wq);
+	destroy_work_on_stack(&req.work);
 
 	return req.result;
 }
@@ -269,6 +273,14 @@ static chunk_t area_location(struct pstore *ps, chunk_t area)
 	return NUM_SNAPSHOT_HDR_CHUNKS + ((ps->exceptions_per_area + 1) * area);
 }
 
+static void skip_metadata(struct pstore *ps)
+{
+	uint32_t stride = ps->exceptions_per_area + 1;
+	chunk_t next_free = ps->next_free;
+	if (sector_div(next_free, stride) == NUM_SNAPSHOT_HDR_CHUNKS)
+		ps->next_free++;
+}
+
 /*
  * Read or write a metadata area.  Remembering to skip the first
  * chunk which holds the header.
@@ -318,8 +330,7 @@ static int read_header(struct pstore *ps, int *new_snapshot)
 		chunk_size_supplied = 0;
 	}
 
-	ps->io_client = dm_io_client_create(sectors_to_pages(ps->store->
-							     chunk_size));
+	ps->io_client = dm_io_client_create();
 	if (IS_ERR(ps->io_client))
 		return PTR_ERR(ps->io_client);
 
@@ -368,11 +379,6 @@ static int read_header(struct pstore *ps, int *new_snapshot)
 		return r;
 	}
 
-	r = dm_io_client_resize(sectors_to_pages(ps->store->chunk_size),
-				ps->io_client);
-	if (r)
-		return r;
-
 	r = alloc_area(ps);
 	return r;
 
@@ -399,40 +405,41 @@ static int write_header(struct pstore *ps)
 /*
  * Access functions for the disk exceptions, these do the endian conversions.
  */
-static struct disk_exception *get_exception(struct pstore *ps, uint32_t index)
+static struct disk_exception *get_exception(struct pstore *ps, void *ps_area,
+					    uint32_t index)
 {
 	BUG_ON(index >= ps->exceptions_per_area);
 
-	return ((struct disk_exception *) ps->area) + index;
+	return ((struct disk_exception *) ps_area) + index;
 }
 
-static void read_exception(struct pstore *ps,
-			   uint32_t index, struct disk_exception *result)
+static void read_exception(struct pstore *ps, void *ps_area,
+			   uint32_t index, struct core_exception *result)
 {
-	struct disk_exception *e = get_exception(ps, index);
+	struct disk_exception *de = get_exception(ps, ps_area, index);
 
 	/* copy it */
-	result->old_chunk = le64_to_cpu(e->old_chunk);
-	result->new_chunk = le64_to_cpu(e->new_chunk);
+	result->old_chunk = le64_to_cpu(de->old_chunk);
+	result->new_chunk = le64_to_cpu(de->new_chunk);
 }
 
 static void write_exception(struct pstore *ps,
-			    uint32_t index, struct disk_exception *de)
+			    uint32_t index, struct core_exception *e)
 {
-	struct disk_exception *e = get_exception(ps, index);
+	struct disk_exception *de = get_exception(ps, ps->area, index);
 
 	/* copy it */
-	e->old_chunk = cpu_to_le64(de->old_chunk);
-	e->new_chunk = cpu_to_le64(de->new_chunk);
+	de->old_chunk = cpu_to_le64(e->old_chunk);
+	de->new_chunk = cpu_to_le64(e->new_chunk);
 }
 
 static void clear_exception(struct pstore *ps, uint32_t index)
 {
-	struct disk_exception *e = get_exception(ps, index);
+	struct disk_exception *de = get_exception(ps, ps->area, index);
 
 	/* clear it */
-	e->old_chunk = 0;
-	e->new_chunk = 0;
+	de->old_chunk = 0;
+	de->new_chunk = 0;
 }
 
 /*
@@ -440,7 +447,7 @@ static void clear_exception(struct pstore *ps, uint32_t index)
  * 'full' is filled in to indicate if the area has been
  * filled.
  */
-static int insert_exceptions(struct pstore *ps,
+static int insert_exceptions(struct pstore *ps, void *ps_area,
 			     int (*callback)(void *callback_context,
 					     chunk_t old, chunk_t new),
 			     void *callback_context,
@@ -448,13 +455,13 @@ static int insert_exceptions(struct pstore *ps,
 {
 	int r;
 	unsigned int i;
-	struct disk_exception de;
+	struct core_exception e;
 
 	/* presume the area is full */
 	*full = 1;
 
 	for (i = 0; i < ps->exceptions_per_area; i++) {
-		read_exception(ps, i, &de);
+		read_exception(ps, ps_area, i, &e);
 
 		/*
 		 * If the new_chunk is pointing at the start of
@@ -462,7 +469,7 @@ static int insert_exceptions(struct pstore *ps,
 		 * is we know that we've hit the end of the
 		 * exceptions.  Therefore the area is not full.
 		 */
-		if (de.new_chunk == 0LL) {
+		if (e.new_chunk == 0LL) {
 			ps->current_committed = i;
 			*full = 0;
 			break;
@@ -471,13 +478,13 @@ static int insert_exceptions(struct pstore *ps,
 		/*
 		 * Keep track of the start of the free chunks.
 		 */
-		if (ps->next_free <= de.new_chunk)
-			ps->next_free = de.new_chunk + 1;
+		if (ps->next_free <= e.new_chunk)
+			ps->next_free = e.new_chunk + 1;
 
 		/*
 		 * Otherwise we add the exception to the snapshot.
 		 */
-		r = callback(callback_context, de.old_chunk, de.new_chunk);
+		r = callback(callback_context, e.old_chunk, e.new_chunk);
 		if (r)
 			return r;
 	}
@@ -491,24 +498,75 @@ static int read_exceptions(struct pstore *ps,
 			   void *callback_context)
 {
 	int r, full = 1;
+	struct dm_bufio_client *client;
+	chunk_t prefetch_area = 0;
+
+	client = dm_bufio_client_create(dm_snap_cow(ps->store->snap)->bdev,
+					ps->store->chunk_size << SECTOR_SHIFT,
+					1, 0, NULL, NULL);
+
+	if (IS_ERR(client))
+		return PTR_ERR(client);
+
+	/*
+	 * Setup for one current buffer + desired readahead buffers.
+	 */
+	dm_bufio_set_minimum_buffers(client, 1 + DM_PREFETCH_CHUNKS);
 
 	/*
 	 * Keeping reading chunks and inserting exceptions until
 	 * we find a partially full area.
 	 */
 	for (ps->current_area = 0; full; ps->current_area++) {
-		r = area_io(ps, READ);
-		if (r)
-			return r;
+		struct dm_buffer *bp;
+		void *area;
+		chunk_t chunk;
+
+		if (unlikely(prefetch_area < ps->current_area))
+			prefetch_area = ps->current_area;
+
+		if (DM_PREFETCH_CHUNKS) do {
+			chunk_t pf_chunk = area_location(ps, prefetch_area);
+			if (unlikely(pf_chunk >= dm_bufio_get_device_size(client)))
+				break;
+			dm_bufio_prefetch(client, pf_chunk, 1);
+			prefetch_area++;
+			if (unlikely(!prefetch_area))
+				break;
+		} while (prefetch_area <= ps->current_area + DM_PREFETCH_CHUNKS);
+
+		chunk = area_location(ps, ps->current_area);
+
+		area = dm_bufio_read(client, chunk, &bp);
+		if (unlikely(IS_ERR(area))) {
+			r = PTR_ERR(area);
+			goto ret_destroy_bufio;
+		}
 
-		r = insert_exceptions(ps, callback, callback_context, &full);
-		if (r)
-			return r;
+		r = insert_exceptions(ps, area, callback, callback_context,
+				      &full);
+
+		if (!full)
+			memcpy(ps->area, area, ps->store->chunk_size << SECTOR_SHIFT);
+
+		dm_bufio_release(bp);
+
+		dm_bufio_forget(client, chunk);
+
+		if (unlikely(r))
+			goto ret_destroy_bufio;
 	}
 
 	ps->current_area--;
 
-	return 0;
+	skip_metadata(ps);
+
+	r = 0;
+
+ret_destroy_bufio:
+	dm_bufio_client_destroy(client);
+
+	return r;
 }
 
 static struct pstore *get_info(struct dm_exception_store *store)
@@ -574,7 +632,7 @@ static int persistent_read_metadata(struct dm_exception_store *store,
 	ps->exceptions_per_area = (ps->store->chunk_size << SECTOR_SHIFT) /
 				  sizeof(struct disk_exception);
 	ps->callbacks = dm_vcalloc(ps->exceptions_per_area,
-			sizeof(*ps->callbacks));
+				   sizeof(*ps->callbacks));
 	if (!ps->callbacks)
 		return -ENOMEM;
 
@@ -622,8 +680,6 @@ static int persistent_prepare_exception(struct dm_exception_store *store,
 					struct dm_exception *e)
 {
 	struct pstore *ps = get_info(store);
-	uint32_t stride;
-	chunk_t next_free;
 	sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
 
 	/* Is there enough room ? */
@@ -636,10 +692,8 @@ static int persistent_prepare_exception(struct dm_exception_store *store,
 	 * Move onto the next free pending, making sure to take
 	 * into account the location of the metadata chunks.
 	 */
-	stride = (ps->exceptions_per_area + 1);
-	next_free = ++ps->next_free;
-	if (sector_div(next_free, stride) == 1)
-		ps->next_free++;
+	ps->next_free++;
+	skip_metadata(ps);
 
 	atomic_inc(&ps->pending_count);
 	return 0;
@@ -652,12 +706,12 @@ static void persistent_commit_exception(struct dm_exception_store *store,
 {
 	unsigned int i;
 	struct pstore *ps = get_info(store);
-	struct disk_exception de;
+	struct core_exception ce;
 	struct commit_callback *cb;
 
-	de.old_chunk = e->old_chunk;
-	de.new_chunk = e->new_chunk;
-	write_exception(ps, ps->current_committed++, &de);
+	ce.old_chunk = e->old_chunk;
+	ce.new_chunk = e->new_chunk;
+	write_exception(ps, ps->current_committed++, &ce);
 
 	/*
 	 * Add the callback to the back of the array.  This code
@@ -681,7 +735,7 @@ static void persistent_commit_exception(struct dm_exception_store *store,
 	 * If we completely filled the current area, then wipe the next one.
 	 */
 	if ((ps->current_committed == ps->exceptions_per_area) &&
-	     zero_disk_area(ps, ps->current_area + 1))
+	    zero_disk_area(ps, ps->current_area + 1))
 		ps->valid = 0;
 
 	/*
@@ -712,7 +766,7 @@ static int persistent_prepare_merge(struct dm_exception_store *store,
 				    chunk_t *last_new_chunk)
 {
 	struct pstore *ps = get_info(store);
-	struct disk_exception de;
+	struct core_exception ce;
 	int nr_consecutive;
 	int r;
 
@@ -733,9 +787,9 @@ static int persistent_prepare_merge(struct dm_exception_store *store,
 		ps->current_committed = ps->exceptions_per_area;
 	}
 
-	read_exception(ps, ps->current_committed - 1, &de);
-	*last_old_chunk = de.old_chunk;
-	*last_new_chunk = de.new_chunk;
+	read_exception(ps, ps->area, ps->current_committed - 1, &ce);
+	*last_old_chunk = ce.old_chunk;
+	*last_new_chunk = ce.new_chunk;
 
 	/*
 	 * Find number of consecutive chunks within the current area,
@@ -743,10 +797,10 @@ static int persistent_prepare_merge(struct dm_exception_store *store,
 	 */
 	for (nr_consecutive = 1; nr_consecutive < ps->current_committed;
 	     nr_consecutive++) {
-		read_exception(ps, ps->current_committed - 1 - nr_consecutive,
-			       &de);
-		if (de.old_chunk != *last_old_chunk - nr_consecutive ||
-		    de.new_chunk != *last_new_chunk - nr_consecutive)
+		read_exception(ps, ps->area,
+			       ps->current_committed - 1 - nr_consecutive, &ce);
+		if (ce.old_chunk != *last_old_chunk - nr_consecutive ||
+		    ce.new_chunk != *last_new_chunk - nr_consecutive)
 			break;
 	}
 
@@ -764,7 +818,7 @@ static int persistent_commit_merge(struct dm_exception_store *store,
 	for (i = 0; i < nr_merged; i++)
 		clear_exception(ps, ps->current_committed - 1 - i);
 
-	r = area_io(ps, WRITE);
+	r = area_io(ps, WRITE_FLUSH_FUA);
 	if (r < 0)
 		return r;
 
@@ -818,7 +872,7 @@ static int persistent_ctr(struct dm_exception_store *store,
 	atomic_set(&ps->pending_count, 0);
 	ps->callbacks = NULL;
 
-	ps->metadata_wq = create_singlethread_workqueue("ksnaphd");
+	ps->metadata_wq = alloc_workqueue("ksnaphd", WQ_MEM_RECLAIM, 0);
 	if (!ps->metadata_wq) {
 		kfree(ps);
 		DMERR("couldn't start header metadata update thread");