From 7b78c170dc4f538cc7ee66f47b3aac3f3974a36c Mon Sep 17 00:00:00 2001
From: Chris Mason <chris.mason@oracle.com>
Date: Wed, 4 Feb 2009 09:12:46 -0500
Subject: [PATCH] Btrfs: Only prep for btree deletion balances when nodes are
mostly empty
Whenever an item deletion is done, we need to balance all the nodes
in the tree to make sure we don't end up with an empty node if a pointer
is deleted. This balance prep happens from the root of the tree down
so we can drop our locks as we go.
reada_for_balance was triggering read-ahead on neighboring nodes even
when no balancing was required. This adds an extra check to avoid
calling balance_level() and avoid reada_for_balance() when a balance
won't be required.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
fs/btrfs/ctree.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 0d1e3b91e7bd..551177c0011a 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1518,18 +1518,19 @@ again:
*/
if (prealloc_block.objectid &&
prealloc_block.offset != b->len) {
- btrfs_set_path_blocking(p);
+ btrfs_release_path(root, p);
btrfs_free_reserved_extent(root,
prealloc_block.objectid,
prealloc_block.offset);
prealloc_block.objectid = 0;
+ goto again;
}
/*
* for higher level blocks, try not to allocate blocks
* with the block and the parent locks held.
*/
- if (level > 1 && !prealloc_block.objectid &&
+ if (level > 0 && !prealloc_block.objectid &&
btrfs_path_lock_waiting(p, level)) {
u32 size = b->len;
u64 hint = b->start;
@@ -1614,7 +1615,9 @@ cow_done:
}
b = p->nodes[level];
slot = p->slots[level];
- } else if (ins_len < 0) {
+ } else if (ins_len < 0 &&
+ btrfs_header_nritems(b) <
+ BTRFS_NODEPTRS_PER_BLOCK(root) / 4) {
int sret;
sret = reada_for_balance(root, p, level);
--
2.34.1