linux/fs/btrfs/tree-defrag.c
David Sterba a2570ef330 btrfs: remove unused btrfs_root::defrag_trans_start
Last touched in 2013 by commit de78b51a28 ("btrfs: remove cache only
arguments from defrag path") that was the only code that used the value.
Now it's only set but never used for anything, so we can remove it.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:28 +02:00

142 lines
3.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2007 Oracle. All rights reserved.
*/
#include <linux/sched.h>
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"
#include "transaction.h"
#include "locking.h"
/*
* Defrag all the leaves in a given btree.
* Read all the leaves and try to get key order to
* better reflect disk order
*/
int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_path *path = NULL;
struct btrfs_key key;
int ret = 0;
int wret;
int level;
int next_key_ret = 0;
u64 last_ret = 0;
if (root->fs_info->extent_root == root) {
/*
* there's recursion here right now in the tree locking,
* we can't defrag the extent root without deadlock
*/
goto out;
}
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
goto out;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
level = btrfs_header_level(root->node);
if (level == 0)
goto out;
if (root->defrag_progress.objectid == 0) {
struct extent_buffer *root_node;
u32 nritems;
root_node = btrfs_lock_root_node(root);
btrfs_set_lock_blocking_write(root_node);
nritems = btrfs_header_nritems(root_node);
root->defrag_max.objectid = 0;
/* from above we know this is not a leaf */
btrfs_node_key_to_cpu(root_node, &root->defrag_max,
nritems - 1);
btrfs_tree_unlock(root_node);
free_extent_buffer(root_node);
memset(&key, 0, sizeof(key));
} else {
memcpy(&key, &root->defrag_progress, sizeof(key));
}
path->keep_locks = 1;
ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION);
if (ret < 0)
goto out;
if (ret > 0) {
ret = 0;
goto out;
}
btrfs_release_path(path);
/*
* We don't need a lock on a leaf. btrfs_realloc_node() will lock all
* leafs from path->nodes[1], so set lowest_level to 1 to avoid later
* a deadlock (attempting to write lock an already write locked leaf).
*/
path->lowest_level = 1;
wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
if (wret < 0) {
ret = wret;
goto out;
}
if (!path->nodes[1]) {
ret = 0;
goto out;
}
/*
* The node at level 1 must always be locked when our path has
* keep_locks set and lowest_level is 1, regardless of the value of
* path->slots[1].
*/
BUG_ON(path->locks[1] == 0);
ret = btrfs_realloc_node(trans, root,
path->nodes[1], 0,
&last_ret,
&root->defrag_progress);
if (ret) {
WARN_ON(ret == -EAGAIN);
goto out;
}
/*
* Now that we reallocated the node we can find the next key. Note that
* btrfs_find_next_key() can release our path and do another search
* without COWing, this is because even with path->keep_locks = 1,
* btrfs_search_slot() / ctree.c:unlock_up() does not keeps a lock on a
* node when path->slots[node_level - 1] does not point to the last
* item or a slot beyond the last item (ctree.c:unlock_up()). Therefore
* we search for the next key after reallocating our node.
*/
path->slots[1] = btrfs_header_nritems(path->nodes[1]);
next_key_ret = btrfs_find_next_key(root, path, &key, 1,
BTRFS_OLDEST_GENERATION);
if (next_key_ret == 0) {
memcpy(&root->defrag_progress, &key, sizeof(key));
ret = -EAGAIN;
}
out:
btrfs_free_path(path);
if (ret == -EAGAIN) {
if (root->defrag_max.objectid > root->defrag_progress.objectid)
goto done;
if (root->defrag_max.type > root->defrag_progress.type)
goto done;
if (root->defrag_max.offset > root->defrag_progress.offset)
goto done;
ret = 0;
}
done:
if (ret != -EAGAIN)
memset(&root->defrag_progress, 0,
sizeof(root->defrag_progress));
return ret;
}