[PATCH 2/7] btrfs: use simpler readahead zone lookups

[David Sterba <dsterba@suse.com>]

No point using radix_tree_gang_lookup if we're looking up just one slot.

Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/reada.c | 52 ++++++++++++++++++++++------------------------------
 1 file changed, 22 insertions(+), 30 deletions(-)

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index fdae8ca79401..dd78af5d265d 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -246,11 +246,9 @@ static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
 	u64 end;
 	int i;
 
-	zone = NULL;
 	spin_lock(&fs_info->reada_lock);
-	ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
-				     logical >> PAGE_SHIFT, 1);
-	if (ret == 1 && logical >= zone->start && logical <= zone->end) {
+	zone = radix_tree_lookup(&dev->reada_zones, logical >> PAGE_SHIFT);
+	if (zone && logical >= zone->start && logical <= zone->end) {
 		kref_get(&zone->refcnt);
 		spin_unlock(&fs_info->reada_lock);
 		return zone;
@@ -297,9 +295,9 @@ static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
 
 	if (ret == -EEXIST) {
 		kfree(zone);
-		ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
-					     logical >> PAGE_SHIFT, 1);
-		if (ret == 1 && logical >= zone->start && logical <= zone->end)
+		zone = radix_tree_lookup(&dev->reada_zones,
+				logical >> PAGE_SHIFT);
+		if (zone && logical >= zone->start && logical <= zone->end)
 			kref_get(&zone->refcnt);
 		else
 			zone = NULL;
@@ -604,7 +602,6 @@ static int reada_pick_zone(struct btrfs_device *dev)
 	u64 top_elems = 0;
 	u64 top_locked_elems = 0;
 	unsigned long index = 0;
-	int ret;
 
 	if (dev->reada_curr_zone) {
 		reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
@@ -615,9 +612,8 @@ static int reada_pick_zone(struct btrfs_device *dev)
 	while (1) {
 		struct reada_zone *zone;
 
-		ret = radix_tree_gang_lookup(&dev->reada_zones,
-					     (void **)&zone, index, 1);
-		if (ret == 0)
+		zone = radix_tree_lookup(&dev->reada_zones, index);
+		if (!zone)
 			break;
 		index = (zone->end >> PAGE_SHIFT) + 1;
 		if (zone->locked) {
@@ -669,19 +665,18 @@ static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
 	 * a contiguous block of extents, we could also coagulate them or use
 	 * plugging to speed things up
 	 */
-	ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
-				     dev->reada_next >> PAGE_SHIFT, 1);
-	if (ret == 0 || re->logical > dev->reada_curr_zone->end) {
+	re = radix_tree_lookup(&dev->reada_extents,
+			dev->reada_next >> PAGE_SHIFT);
+	if (!re || re->logical > dev->reada_curr_zone->end) {
 		ret = reada_pick_zone(dev);
 		if (!ret) {
 			spin_unlock(&fs_info->reada_lock);
 			return 0;
 		}
-		re = NULL;
-		ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
-					dev->reada_next >> PAGE_SHIFT, 1);
+		re = radix_tree_lookup(&dev->reada_extents,
+				dev->reada_next >> PAGE_SHIFT);
 	}
-	if (ret == 0) {
+	if (!re) {
 		spin_unlock(&fs_info->reada_lock);
 		return 0;
 	}
@@ -809,7 +804,6 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 	struct btrfs_device *device;
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	unsigned long index;
-	int ret;
 	int i;
 	int j;
 	int cnt;
@@ -821,9 +815,9 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 		index = 0;
 		while (1) {
 			struct reada_zone *zone;
-			ret = radix_tree_gang_lookup(&device->reada_zones,
-						     (void **)&zone, index, 1);
-			if (ret == 0)
+
+			zone = radix_tree_lookup(&device->reada_zones, index);
+			if (!zone)
 				break;
 			pr_debug("  zone %llu-%llu elems %llu locked %d devs",
 				    zone->start, zone->end, zone->elems,
@@ -841,11 +835,10 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 		cnt = 0;
 		index = 0;
 		while (all) {
-			struct reada_extent *re = NULL;
+			struct reada_extent *re;
 
-			ret = radix_tree_gang_lookup(&device->reada_extents,
-						     (void **)&re, index, 1);
-			if (ret == 0)
+			re = radix_tree_lookup(&device->reada_extents, index);
+			if (!re)
 				break;
 			pr_debug("  re: logical %llu size %u empty %d scheduled %d",
 				re->logical, fs_info->nodesize,
@@ -870,11 +863,10 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 	index = 0;
 	cnt = 0;
 	while (all) {
-		struct reada_extent *re = NULL;
+		struct reada_extent *re;
 
-		ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
-					     index, 1);
-		if (ret == 0)
+		re = radix_tree_lookup(&fs_info->reada_tree, index);
+		if (!re)
 			break;
 		if (!re->scheduled) {
 			index = (re->logical >> PAGE_SHIFT) + 1;
-- 
2.12.0