1 files changed, 99 insertions, 62 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 60d684266959..a5501edc3c9f 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -987,11 +987,18 @@ tree_search_offset(struct btrfs_block_group_cache *block_group,
         return entry;
 }
 
-static void unlink_free_space(struct btrfs_block_group_cache *block_group,
-                              struct btrfs_free_space *info)
+static inline void
+__unlink_free_space(struct btrfs_block_group_cache *block_group,
+                    struct btrfs_free_space *info)
 {
         rb_erase(&info->offset_index, &block_group->free_space_offset);
         block_group->free_extents--;
+}
+
+static void unlink_free_space(struct btrfs_block_group_cache *block_group,
+                              struct btrfs_free_space *info)
+{
+        __unlink_free_space(block_group, info);
         block_group->free_space -= info->bytes;
 }
 
@@ -1016,14 +1023,18 @@ static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
         u64 max_bytes;
         u64 bitmap_bytes;
         u64 extent_bytes;
+        u64 size = block_group->key.offset;
 
         /*
          * The goal is to keep the total amount of memory used per 1gb of space
          * at or below 32k, so we need to adjust how much memory we allow to be
          * used by extent based free space tracking
          */
-        max_bytes = MAX_CACHE_BYTES_PER_GIG *
-                (div64_u64(block_group->key.offset, 1024 * 1024 * 1024));
+        if (size < 1024 * 1024 * 1024)
+                max_bytes = MAX_CACHE_BYTES_PER_GIG;
+        else
+                max_bytes = MAX_CACHE_BYTES_PER_GIG *
+                        div64_u64(size, 1024 * 1024 * 1024);
 
         /*
          * we want to account for 1 more bitmap than what we have so we can make
@@ -1171,6 +1182,16 @@ static void add_new_bitmap(struct btrfs_block_group_cache *block_group,
         recalculate_thresholds(block_group);
 }
 
+static void free_bitmap(struct btrfs_block_group_cache *block_group,
+                        struct btrfs_free_space *bitmap_info)
+{
+        unlink_free_space(block_group, bitmap_info);
+        kfree(bitmap_info->bitmap);
+        kfree(bitmap_info);
+        block_group->total_bitmaps--;
+        recalculate_thresholds(block_group);
+}
+
 static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_group,
                               struct btrfs_free_space *bitmap_info,
                               u64 *offset, u64 *bytes)
@@ -1211,13 +1232,8 @@ again:
 
         if (*bytes) {
                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
-                if (!bitmap_info->bytes) {
-                        unlink_free_space(block_group, bitmap_info);
-                        kfree(bitmap_info->bitmap);
-                        kfree(bitmap_info);
-                        block_group->total_bitmaps--;
-                        recalculate_thresholds(block_group);
-                }
+                if (!bitmap_info->bytes)
+                        free_bitmap(block_group, bitmap_info);
 
                 /*
                  * no entry after this bitmap, but we still have bytes to
@@ -1250,13 +1266,8 @@ again:
                         return -EAGAIN;
 
                 goto again;
-        } else if (!bitmap_info->bytes) {
-                unlink_free_space(block_group, bitmap_info);
-                kfree(bitmap_info->bitmap);
-                kfree(bitmap_info);
-                block_group->total_bitmaps--;
-                recalculate_thresholds(block_group);
-        }
+        } else if (!bitmap_info->bytes)
+                free_bitmap(block_group, bitmap_info);
 
         return 0;
 }
@@ -1359,22 +1370,14 @@ out:
         return ret;
 }
 
-int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
-                         u64 offset, u64 bytes)
+bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
+                          struct btrfs_free_space *info, bool update_stat)
 {
-        struct btrfs_free_space *right_info = NULL;
-        struct btrfs_free_space *left_info = NULL;
-        struct btrfs_free_space *info = NULL;
-        int ret = 0;
-
-        info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
-        if (!info)
-                return -ENOMEM;
-
-        info->offset = offset;
-        info->bytes = bytes;
-
-        spin_lock(&block_group->tree_lock);
+        struct btrfs_free_space *left_info;
+        struct btrfs_free_space *right_info;
+        bool merged = false;
+        u64 offset = info->offset;
+        u64 bytes = info->bytes;
 
         /*
          * first we want to see if there is free space adjacent to the range we
@@ -1388,37 +1391,62 @@ int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
         else
                 left_info = tree_search_offset(block_group, offset - 1, 0, 0);
 
-        /*
-         * If there was no extent directly to the left or right of this new
-         * extent then we know we're going to have to allocate a new extent, so
-         * before we do that see if we need to drop this into a bitmap
-         */
-        if ((!left_info || left_info->bitmap) &&
-            (!right_info || right_info->bitmap)) {
-                ret = insert_into_bitmap(block_group, info);
-
-                if (ret < 0) {
-                        goto out;
-                } else if (ret) {
-                        ret = 0;
-                        goto out;
-                }
-        }
-
         if (right_info && !right_info->bitmap) {
-                unlink_free_space(block_group, right_info);
+                if (update_stat)
+                        unlink_free_space(block_group, right_info);
+                else
+                        __unlink_free_space(block_group, right_info);
                 info->bytes += right_info->bytes;
                 kfree(right_info);
+                merged = true;
         }
 
         if (left_info && !left_info->bitmap &&
             left_info->offset + left_info->bytes == offset) {
-                unlink_free_space(block_group, left_info);
+                if (update_stat)
+                        unlink_free_space(block_group, left_info);
+                else
+                        __unlink_free_space(block_group, left_info);
                 info->offset = left_info->offset;
                 info->bytes += left_info->bytes;
                 kfree(left_info);
+                merged = true;
         }
 
+        return merged;
+}
+
+int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
+                         u64 offset, u64 bytes)
+{
+        struct btrfs_free_space *info;
+        int ret = 0;
+
+        info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
+        if (!info)
+                return -ENOMEM;
+
+        info->offset = offset;
+        info->bytes = bytes;
+
+        spin_lock(&block_group->tree_lock);
+
+        if (try_merge_free_space(block_group, info, true))
+                goto link;
+
+        /*
+         * There was no extent directly to the left or right of this new
+         * extent then we know we're going to have to allocate a new extent, so
+         * before we do that see if we need to drop this into a bitmap
+         */
+        ret = insert_into_bitmap(block_group, info);
+        if (ret < 0) {
+                goto out;
+        } else if (ret) {
+                ret = 0;
+                goto out;
+        }
+link:
         ret = link_free_space(block_group, info);
         if (ret)
                 kfree(info);
@@ -1621,6 +1649,7 @@ __btrfs_return_cluster_to_free_space(
                 node = rb_next(&entry->offset_index);
                 rb_erase(&entry->offset_index, &cluster->root);
                 BUG_ON(entry->bitmap);
+                try_merge_free_space(block_group, entry, false);
                 tree_insert_offset(&block_group->free_space_offset,
                                    entry->offset, &entry->offset_index, 0);
         }
@@ -1685,13 +1714,8 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
         ret = offset;
         if (entry->bitmap) {
                 bitmap_clear_bits(block_group, entry, offset, bytes);
-                if (!entry->bytes) {
-                        unlink_free_space(block_group, entry);
-                        kfree(entry->bitmap);
-                        kfree(entry);
-                        block_group->total_bitmaps--;
-                        recalculate_thresholds(block_group);
-                }
+                if (!entry->bytes)
+                        free_bitmap(block_group, entry);
         } else {
                 unlink_free_space(block_group, entry);
                 entry->offset += bytes;
@@ -1789,6 +1813,8 @@ static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
 
         ret = search_start;
         bitmap_clear_bits(block_group, entry, ret, bytes);
+        if (entry->bytes == 0)
+                free_bitmap(block_group, entry);
 out:
         spin_unlock(&cluster->lock);
         spin_unlock(&block_group->tree_lock);
@@ -1842,15 +1868,26 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
                 entry->offset += bytes;
                 entry->bytes -= bytes;
 
-                if (entry->bytes == 0) {
+                if (entry->bytes == 0)
                         rb_erase(&entry->offset_index, &cluster->root);
-                        kfree(entry);
-                }
                 break;
         }
 out:
         spin_unlock(&cluster->lock);
 
+        if (!ret)
+                return 0;
+
+        spin_lock(&block_group->tree_lock);
+
+        block_group->free_space -= bytes;
+        if (entry->bytes == 0) {
+                block_group->free_extents--;
+                kfree(entry);
+        }
+
+        spin_unlock(&block_group->tree_lock);
+
         return ret;
 }