diff options
Diffstat (limited to 'fs/btrfs/ctree.c')
| -rw-r--r-- | fs/btrfs/ctree.c | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 26c2d50ea2db..a484fb72a01f 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1279,12 +1279,13 @@ static void reada_for_search(struct btrfs_fs_info *fs_info, u64 search; u64 target; u64 nread = 0; + u64 nread_max; struct extent_buffer *eb; u32 nr; u32 blocksize; u32 nscan = 0; - if (level != 1) + if (level != 1 && path->reada != READA_FORWARD_ALWAYS) return; if (!path->nodes[level]) @@ -1292,6 +1293,20 @@ static void reada_for_search(struct btrfs_fs_info *fs_info, node = path->nodes[level]; + /* + * Since the time between visiting leaves is much shorter than the time + * between visiting nodes, limit read ahead of nodes to 1, to avoid too + * much IO at once (possibly random). + */ + if (path->reada == READA_FORWARD_ALWAYS) { + if (level > 1) + nread_max = node->fs_info->nodesize; + else + nread_max = SZ_128K; + } else { + nread_max = SZ_64K; + } + search = btrfs_node_blockptr(node, slot); blocksize = fs_info->nodesize; eb = find_extent_buffer(fs_info, search); @@ -1310,7 +1325,8 @@ static void reada_for_search(struct btrfs_fs_info *fs_info, if (nr == 0) break; nr--; - } else if (path->reada == READA_FORWARD) { + } else if (path->reada == READA_FORWARD || + path->reada == READA_FORWARD_ALWAYS) { nr++; if (nr >= nritems) break; @@ -1321,13 +1337,14 @@ static void reada_for_search(struct btrfs_fs_info *fs_info, break; } search = btrfs_node_blockptr(node, nr); - if ((search <= target && target - search <= 65536) || + if (path->reada == READA_FORWARD_ALWAYS || + (search <= target && target - search <= 65536) || (search > target && search - target <= 65536)) { btrfs_readahead_node_child(node, nr); nread += blocksize; } nscan++; - if ((nread > 65536 || nscan > 32)) + if (nread > nread_max || nscan > 32) break; } } @@ -1436,6 +1453,9 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p, tmp = find_extent_buffer(fs_info, blocknr); if (tmp) { + if (p->reada == READA_FORWARD_ALWAYS) + reada_for_search(fs_info, p, level, slot, key->objectid); + /* first we do an atomic uptodate check */ if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) { /* |