[PATCH v2 21/21] btrfs: factor out prepare_allocation()

From: Naohiro Aota <naohiro.aota@wdc.com>
To: linux-btrfs@vger.kernel.org, David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
	Nikolay Borisov <nborisov@suse.com>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
	Hannes Reinecke <hare@suse.com>,
	Anand Jain <anand.jain@oracle.com>,
	linux-fsdevel@vger.kernel.org,
	Naohiro Aota <naohiro.aota@wdc.com>
Subject: [PATCH v2 21/21] btrfs: factor out prepare_allocation()
Date: Wed, 12 Feb 2020 16:20:48 +0900	[thread overview]
Message-ID: <20200212072048.629856-22-naohiro.aota@wdc.com> (raw)
In-Reply-To: <20200212072048.629856-1-naohiro.aota@wdc.com>

This function finally factor out prepare_allocation() form
find_free_extent(). This function is called before the allocation loop and
a specific allocator function like prepare_allocation_clustered() should
initialize their private information and can set proper hint_byte to
indicate where to start the allocation with.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
 fs/btrfs/extent-tree.c | 110 +++++++++++++++++++++++++----------------
 1 file changed, 68 insertions(+), 42 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3ab0d2f5d718..6da7f6e03767 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3868,6 +3868,71 @@ static int find_free_extent_update_loop(struct btrfs_fs_info *fs_info,
 	return -ENOSPC;
 }
 
+static int prepare_allocation_clustered(struct btrfs_fs_info *fs_info,
+					struct find_free_extent_ctl *ffe_ctl,
+					struct btrfs_space_info *space_info,
+					struct btrfs_key *ins)
+{
+	/*
+	 * If our free space is heavily fragmented we may not be able to make
+	 * big contiguous allocations, so instead of doing the expensive search
+	 * for free space, simply return ENOSPC with our max_extent_size so we
+	 * can go ahead and search for a more manageable chunk.
+	 *
+	 * If our max_extent_size is large enough for our allocation simply
+	 * disable clustering since we will likely not be able to find enough
+	 * space to create a cluster and induce latency trying.
+	 */
+	if (unlikely(space_info->max_extent_size)) {
+		spin_lock(&space_info->lock);
+		if (space_info->max_extent_size &&
+		    ffe_ctl->num_bytes > space_info->max_extent_size) {
+			ins->offset = space_info->max_extent_size;
+			spin_unlock(&space_info->lock);
+			return -ENOSPC;
+		} else if (space_info->max_extent_size) {
+			ffe_ctl->use_cluster = false;
+		}
+		spin_unlock(&space_info->lock);
+	}
+
+	ffe_ctl->last_ptr = fetch_cluster_info(fs_info, space_info,
+					       &ffe_ctl->empty_cluster);
+	if (ffe_ctl->last_ptr) {
+		struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
+
+		spin_lock(&last_ptr->lock);
+		if (last_ptr->block_group)
+			ffe_ctl->hint_byte = last_ptr->window_start;
+		if (last_ptr->fragmented) {
+			/*
+			 * We still set window_start so we can keep track of the
+			 * last place we found an allocation to try and save
+			 * some time.
+			 */
+			ffe_ctl->hint_byte = last_ptr->window_start;
+			ffe_ctl->use_cluster = false;
+		}
+		spin_unlock(&last_ptr->lock);
+	}
+
+	return 0;
+}
+
+static int prepare_allocation(struct btrfs_fs_info *fs_info,
+			      struct find_free_extent_ctl *ffe_ctl,
+			      struct btrfs_space_info *space_info,
+			      struct btrfs_key *ins)
+{
+	switch (ffe_ctl->policy) {
+	case BTRFS_EXTENT_ALLOC_CLUSTERED:
+		return prepare_allocation_clustered(fs_info, ffe_ctl,
+						    space_info, ins);
+	default:
+		BUG();
+	}
+}
+
 /*
  * walks the btree of allocated extents and find a hole of a given size.
  * The key ins is changed to record the hole:
@@ -3937,48 +4002,9 @@ static noinline int find_free_extent(struct btrfs_fs_info *fs_info,
 		return -ENOSPC;
 	}
 
-	/*
-	 * If our free space is heavily fragmented we may not be able to make
-	 * big contiguous allocations, so instead of doing the expensive search
-	 * for free space, simply return ENOSPC with our max_extent_size so we
-	 * can go ahead and search for a more manageable chunk.
-	 *
-	 * If our max_extent_size is large enough for our allocation simply
-	 * disable clustering since we will likely not be able to find enough
-	 * space to create a cluster and induce latency trying.
-	 */
-	if (unlikely(space_info->max_extent_size)) {
-		spin_lock(&space_info->lock);
-		if (space_info->max_extent_size &&
-		    num_bytes > space_info->max_extent_size) {
-			ins->offset = space_info->max_extent_size;
-			spin_unlock(&space_info->lock);
-			return -ENOSPC;
-		} else if (space_info->max_extent_size) {
-			ffe_ctl.use_cluster = false;
-		}
-		spin_unlock(&space_info->lock);
-	}
-
-	ffe_ctl.last_ptr = fetch_cluster_info(fs_info, space_info,
-					      &ffe_ctl.empty_cluster);
-	if (ffe_ctl.last_ptr) {
-		struct btrfs_free_cluster *last_ptr = ffe_ctl.last_ptr;
-
-		spin_lock(&last_ptr->lock);
-		if (last_ptr->block_group)
-			ffe_ctl.hint_byte = last_ptr->window_start;
-		if (last_ptr->fragmented) {
-			/*
-			 * We still set window_start so we can keep track of the
-			 * last place we found an allocation to try and save
-			 * some time.
-			 */
-			ffe_ctl.hint_byte = last_ptr->window_start;
-			ffe_ctl.use_cluster = false;
-		}
-		spin_unlock(&last_ptr->lock);
-	}
+	ret = prepare_allocation(fs_info, &ffe_ctl, space_info, ins);
+	if (ret < 0)
+		return ret;
 
 	ffe_ctl.search_start = max(ffe_ctl.search_start,
 				   first_logical_byte(fs_info, 0));
-- 
2.25.0

