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Btrfs: Only prep for btree deletion balances when nodes are mostly empty

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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>
This commit is contained in:
Chris Mason 2009-02-04 09:12:46 -05:00
parent 12f4daccfc
commit 7b78c170dc
1 changed files with 6 additions and 3 deletions
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9
fs/btrfs/ctree.c
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@ -1518,18 +1518,19 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
*/
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 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
}
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);