Btrfs: Tune readahead during defrag to avoid reading too much at once
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1cf125a..c4fe377 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1856,27 +1856,44 @@
}
static void noinline reada_walk_down(struct btrfs_root *root,
- struct extent_buffer *node)
+ struct extent_buffer *node,
+ int slot)
{
- int i;
- u32 nritems;
u64 bytenr;
- int ret;
+ u64 last = 0;
+ u32 nritems;
u32 refs;
- int level;
u32 blocksize;
+ int ret;
+ int i;
+ int level;
+ int skipped = 0;
nritems = btrfs_header_nritems(node);
level = btrfs_header_level(node);
- for (i = 0; i < nritems; i++) {
+ if (level)
+ return;
+
+ for (i = slot; i < nritems && skipped < 32; i++) {
bytenr = btrfs_node_blockptr(node, i);
- blocksize = btrfs_level_size(root, level - 1);
- ret = lookup_extent_ref(NULL, root, bytenr, blocksize, &refs);
- BUG_ON(ret);
- if (refs != 1)
+ if (last && ((bytenr > last && bytenr - last > 32 * 1024) ||
+ (last > bytenr && last - bytenr > 32 * 1024))) {
+ skipped++;
continue;
+ }
+ blocksize = btrfs_level_size(root, level - 1);
+ if (i != slot) {
+ ret = lookup_extent_ref(NULL, root, bytenr,
+ blocksize, &refs);
+ BUG_ON(ret);
+ if (refs != 1) {
+ skipped++;
+ continue;
+ }
+ }
mutex_unlock(&root->fs_info->fs_mutex);
ret = readahead_tree_block(root, bytenr, blocksize);
+ last = bytenr + blocksize;
cond_resched();
mutex_lock(&root->fs_info->fs_mutex);
if (ret)
@@ -1919,9 +1936,6 @@
WARN_ON(*level >= BTRFS_MAX_LEVEL);
cur = path->nodes[*level];
- if (*level > 0 && path->slots[*level] == 0)
- reada_walk_down(root, cur);
-
if (btrfs_header_level(cur) != *level)
WARN_ON(1);
@@ -1951,6 +1965,7 @@
next = btrfs_find_tree_block(root, bytenr, blocksize);
if (!next || !btrfs_buffer_uptodate(next)) {
free_extent_buffer(next);
+ reada_walk_down(root, cur, path->slots[*level]);
mutex_unlock(&root->fs_info->fs_mutex);
next = read_tree_block(root, bytenr, blocksize);
mutex_lock(&root->fs_info->fs_mutex);