btrfs: reada: Pass reada_extent into __readahead_hook directly

reada_start_machine_dev() already have reada_extent pointer, pass
it into __readahead_hook() directly instead of search radix_tree
will make code run faster.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index f7642e5..203bec4 100644 (file)
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -105,33 +105,21 @@ static int reada_add_block(struct reada_control *rc, u64 logical,
 
 /* recurses */
 /* in case of err, eb might be NULL */
-static int __readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
-                           u64 start, int err)
+static void __readahead_hook(struct btrfs_root *root, struct reada_extent *re,
+                            struct extent_buffer *eb, u64 start, int err)
 {
        int level = 0;
        int nritems;
        int i;
        u64 bytenr;
        u64 generation;
-       struct reada_extent *re;
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct list_head list;
-       unsigned long index = start >> PAGE_CACHE_SHIFT;
        struct btrfs_device *for_dev;
 
        if (eb)
                level = btrfs_header_level(eb);
 
-       /* find extent */
-       spin_lock(&fs_info->reada_lock);
-       re = radix_tree_lookup(&fs_info->reada_tree, index);
-       if (re)
-               re->refcnt++;
-       spin_unlock(&fs_info->reada_lock);
-
-       if (!re)
-               return -1;
-
        spin_lock(&re->lock);
        /*
         * just take the full list from the extent. afterwards we
@@ -221,11 +209,11 @@ static int __readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
 
                reada_extent_put(fs_info, re);  /* one ref for each entry */
        }
-       reada_extent_put(fs_info, re);  /* our ref */
+
        if (for_dev)
                atomic_dec(&for_dev->reada_in_flight);
 
-       return 0;
+       return;
 }
 
 /*
@@ -235,12 +223,27 @@ static int __readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
 int btree_readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
                         u64 start, int err)
 {
-       int ret;
+       int ret = 0;
+       struct reada_extent *re;
+       struct btrfs_fs_info *fs_info = root->fs_info;
 
-       ret = __readahead_hook(root, eb, start, err);
+       /* find extent */
+       spin_lock(&fs_info->reada_lock);
+       re = radix_tree_lookup(&fs_info->reada_tree,
+                              start >> PAGE_CACHE_SHIFT);
+       if (re)
+               re->refcnt++;
+       spin_unlock(&fs_info->reada_lock);
+       if (!re) {
+               ret = -1;
+               goto start_machine;
+       }
 
-       reada_start_machine(root->fs_info);
+       __readahead_hook(fs_info, re, eb, start, err);
+       reada_extent_put(fs_info, re);  /* our ref */
 
+start_machine:
+       reada_start_machine(fs_info);
        return ret;
 }
 
@@ -721,9 +724,9 @@ static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
        ret = reada_tree_block_flagged(fs_info->extent_root, logical,
                        mirror_num, &eb);
        if (ret)
-               __readahead_hook(fs_info->extent_root, NULL, logical, ret);
+               __readahead_hook(fs_info->extent_root, re, NULL, logical, ret);
        else if (eb)
-               __readahead_hook(fs_info->extent_root, eb, eb->start, ret);
+               __readahead_hook(fs_info->extent_root, re, eb, eb->start, ret);
 
        if (eb)
                free_extent_buffer(eb);