btrfs: subpage: make readahead work properly

In readahead infrastructure, we are using a lot of hard coded PAGE_SHIFT
while we're not doing anything specific to PAGE_SIZE.

One of the most affected part is the radix tree operation of
btrfs_fs_info::reada_tree.

If using PAGE_SHIFT, subpage metadata readahead is broken and does no
help reading metadata ahead.

Fix the problem by using btrfs_fs_info::sectorsize_bits so that
readahead could work for subpage.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/reada.c

@@ -209,7 +209,7 @@ int btree_readahead_hook(struct extent_buffer *eb, int err)
 	/* find extent */
 	spin_lock(&fs_info->reada_lock);
 	re = radix_tree_lookup(&fs_info->reada_tree,
-			       eb->start >> PAGE_SHIFT);
+			       eb->start >> fs_info->sectorsize_bits);
 	if (re)
 		re->refcnt++;
 	spin_unlock(&fs_info->reada_lock);
@@ -240,7 +240,7 @@ static struct reada_zone *reada_find_zone(struct btrfs_device *dev, u64 logical,
 	zone = NULL;
 	spin_lock(&fs_info->reada_lock);
 	ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
-				     logical >> PAGE_SHIFT, 1);
+				     logical >> fs_info->sectorsize_bits, 1);
 	if (ret == 1 && logical >= zone->start && logical <= zone->end) {
 		kref_get(&zone->refcnt);
 		spin_unlock(&fs_info->reada_lock);
@@ -283,13 +283,13 @@ static struct reada_zone *reada_find_zone(struct btrfs_device *dev, u64 logical,
 
 	spin_lock(&fs_info->reada_lock);
 	ret = radix_tree_insert(&dev->reada_zones,
-				(unsigned long)(zone->end >> PAGE_SHIFT),
+			(unsigned long)(zone->end >> fs_info->sectorsize_bits),
 			zone);
 
 	if (ret == -EEXIST) {
 		kfree(zone);
 		ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
-					     logical >> PAGE_SHIFT, 1);
+					logical >> fs_info->sectorsize_bits, 1);
 		if (ret == 1 && logical >= zone->start && logical <= zone->end)
 			kref_get(&zone->refcnt);
 		else
@@ -315,7 +315,7 @@ static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 	u64 length;
 	int real_stripes;
 	int nzones = 0;
-	unsigned long index = logical >> PAGE_SHIFT;
+	unsigned long index = logical >> fs_info->sectorsize_bits;
 	int dev_replace_is_ongoing;
 	int have_zone = 0;
 
@@ -497,7 +497,7 @@ static void reada_extent_put(struct btrfs_fs_info *fs_info,
 			     struct reada_extent *re)
 {
 	int i;
-	unsigned long index = re->logical >> PAGE_SHIFT;
+	unsigned long index = re->logical >> fs_info->sectorsize_bits;
 
 	spin_lock(&fs_info->reada_lock);
 	if (--re->refcnt) {
@@ -538,11 +538,12 @@ static void reada_extent_put(struct btrfs_fs_info *fs_info,
 static void reada_zone_release(struct kref *kref)
 {
 	struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
+	struct btrfs_fs_info *fs_info = zone->device->fs_info;
 
-	lockdep_assert_held(&zone->device->fs_info->reada_lock);
+	lockdep_assert_held(&fs_info->reada_lock);
 
 	radix_tree_delete(&zone->device->reada_zones,
-			  zone->end >> PAGE_SHIFT);
+			  zone->end >> fs_info->sectorsize_bits);
 
 	kfree(zone);
 }
@@ -593,7 +594,7 @@ static int reada_add_block(struct reada_control *rc, u64 logical,
 static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
 {
 	int i;
-	unsigned long index = zone->end >> PAGE_SHIFT;
+	unsigned long index = zone->end >> zone->device->fs_info->sectorsize_bits;
 
 	for (i = 0; i < zone->ndevs; ++i) {
 		struct reada_zone *peer;
@@ -628,7 +629,7 @@ static int reada_pick_zone(struct btrfs_device *dev)
 					     (void **)&zone, index, 1);
 		if (ret == 0)
 			break;
-		index = (zone->end >> PAGE_SHIFT) + 1;
+		index = (zone->end >> dev->fs_info->sectorsize_bits) + 1;
 		if (zone->locked) {
 			if (zone->elems > top_locked_elems) {
 				top_locked_elems = zone->elems;
@@ -709,7 +710,7 @@ static int reada_start_machine_dev(struct btrfs_device *dev)
 	 * plugging to speed things up
 	 */
 	ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
-				     dev->reada_next >> PAGE_SHIFT, 1);
+				dev->reada_next >> fs_info->sectorsize_bits, 1);
 	if (ret == 0 || re->logical > dev->reada_curr_zone->end) {
 		ret = reada_pick_zone(dev);
 		if (!ret) {
@@ -718,7 +719,7 @@ static int reada_start_machine_dev(struct btrfs_device *dev)
 		}
 		re = NULL;
 		ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
-					dev->reada_next >> PAGE_SHIFT, 1);
+				dev->reada_next >> fs_info->sectorsize_bits, 1);
 	}
 	if (ret == 0) {
 		spin_unlock(&fs_info->reada_lock);
@@ -885,7 +886,7 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 				pr_cont(" curr off %llu",
 					device->reada_next - zone->start);
 			pr_cont("\n");
-			index = (zone->end >> PAGE_SHIFT) + 1;
+			index = (zone->end >> fs_info->sectorsize_bits) + 1;
 		}
 		cnt = 0;
 		index = 0;
@@ -910,7 +911,7 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 				}
 			}
 			pr_cont("\n");
-			index = (re->logical >> PAGE_SHIFT) + 1;
+			index = (re->logical >> fs_info->sectorsize_bits) + 1;
 			if (++cnt > 15)
 				break;
 		}
@@ -926,7 +927,7 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 		if (ret == 0)
 			break;
 		if (!re->scheduled) {
-			index = (re->logical >> PAGE_SHIFT) + 1;
+			index = (re->logical >> fs_info->sectorsize_bits) + 1;
 			continue;
 		}
 		pr_debug("re: logical %llu size %u list empty %d scheduled %d",
@@ -942,7 +943,7 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 			}
 		}
 		pr_cont("\n");
-		index = (re->logical >> PAGE_SHIFT) + 1;
+		index = (re->logical >> fs_info->sectorsize_bits) + 1;
 	}
 	spin_unlock(&fs_info->reada_lock);
 }