Commit 240d5d48 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: tune btrfs unplug functions for a small number of devices

When btrfs unplugs, it tries to find the correct device to unplug
via search through the extent_map tree.  This avoids unplugging
a device that doesn't need it, but is a waste of time for filesystems
with a small number of devices.

This patch checks the total number of devices before doing the

Signed-off-by: default avatarChris Mason <>
parent b47eda86
......@@ -1201,6 +1201,16 @@ void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
inode = mapping->host;
* don't do the expensive searching for a small number of
* devices
if (BTRFS_I(inode)->root->fs_info->fs_devices->open_devices <= 2) {
__unplug_io_fn(bdi, page);
offset = page_offset(page);
em_tree = &BTRFS_I(inode)->extent_tree;
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