[PATCH 1/3] btrfs: Fix in-segment calculation for reada

[PATCH 1/3] btrfs: Fix in-segment calculation for reada

[Zhao Lei]

reada_zone->end is end pos of segment:
 end = start + cache->key.offset - 1;

So we need to use "<=" in condition to judge is a pos in the
segment.

The problem happened rearly, because logical pos rarely pointed
to last 4k of a blockgroup, but we need to fix it to make code
right in logic.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
 fs/btrfs/reada.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 7bbd656..6fb9c37 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -265,7 +265,7 @@ static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
 	spin_unlock(&fs_info->reada_lock);
 
 	if (ret == 1) {
-		if (logical >= zone->start && logical < zone->end)
+		if (logical >= zone->start && logical <= zone->end)
 			return zone;
 		spin_lock(&fs_info->reada_lock);
 		kref_put(&zone->refcnt, reada_zone_release);
@@ -684,7 +684,7 @@ static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
 	 */
 	ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
 				     dev->reada_next >> PAGE_CACHE_SHIFT, 1);
-	if (ret == 0 || re->logical >= dev->reada_curr_zone->end) {
+	if (ret == 0 || re->logical > dev->reada_curr_zone->end) {
 		ret = reada_pick_zone(dev);
 		if (!ret) {
 			spin_unlock(&fs_info->reada_lock);
-- 
1.8.5.1

[PATCH 2/3] btrfs: reduce additional fs_info->reada_lock in reada_find_zone

[Zhao Lei]

We can avoid additional locking-acquirment and one pair of
kref_get/put by combine two condition.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
 fs/btrfs/reada.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 6fb9c37..d8116fe 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -260,18 +260,14 @@ static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
 	spin_lock(&fs_info->reada_lock);
 	ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
 				     logical >> PAGE_CACHE_SHIFT, 1);
-	if (ret == 1)
+	if (ret == 1 && logical >= zone->start && logical <= zone->end) {
 		kref_get(&zone->refcnt);
-	spin_unlock(&fs_info->reada_lock);
-
-	if (ret == 1) {
-		if (logical >= zone->start && logical <= zone->end)
-			return zone;
-		spin_lock(&fs_info->reada_lock);
-		kref_put(&zone->refcnt, reada_zone_release);
 		spin_unlock(&fs_info->reada_lock);
+		return zone;
 	}
 
+	spin_unlock(&fs_info->reada_lock);
+
 	cache = btrfs_lookup_block_group(fs_info, logical);
 	if (!cache)
 		return NULL;
-- 
1.8.5.1

[PATCH 3/3] btrfs: Add missed segment checking in reada_find_zone

[Zhao Lei]

In rechecking zone-in-tree, we still need to check zone include
our logical address.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
 fs/btrfs/reada.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index d8116fe..c65b42f 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -303,8 +303,10 @@ static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
 		kfree(zone);
 		ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
 					     logical >> PAGE_CACHE_SHIFT, 1);
-		if (ret == 1)
+		if (ret == 1 && logical >= zone->start && logical <= zone->end)
 			kref_get(&zone->refcnt);
+		else
+			zone = NULL;
 	}
 	spin_unlock(&fs_info->reada_lock);
 
-- 
1.8.5.1