Btrfs: use the right node in reada_for_balance
reada_for_balance was using the wrong index into the path node array,
so it wasn't reading the right blocks. We never directly used the
results of the read done by this function because the btree search is
started over at the end.
This fixes reada_for_balance to reada in the correct node and to
avoid searching past the last slot in the node. It also makes sure to
hold the parent lock while we are finding the nodes to read.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index e5b2533..a99f1c2 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1325,12 +1325,12 @@
int ret = 0;
int blocksize;
- parent = path->nodes[level - 1];
+ parent = path->nodes[level + 1];
if (!parent)
return 0;
nritems = btrfs_header_nritems(parent);
- slot = path->slots[level];
+ slot = path->slots[level + 1];
blocksize = btrfs_level_size(root, level);
if (slot > 0) {
@@ -1341,7 +1341,7 @@
block1 = 0;
free_extent_buffer(eb);
}
- if (slot < nritems) {
+ if (slot + 1 < nritems) {
block2 = btrfs_node_blockptr(parent, slot + 1);
gen = btrfs_node_ptr_generation(parent, slot + 1);
eb = btrfs_find_tree_block(root, block2, blocksize);
@@ -1351,7 +1351,11 @@
}
if (block1 || block2) {
ret = -EAGAIN;
+
+ /* release the whole path */
btrfs_release_path(root, path);
+
+ /* read the blocks */
if (block1)
readahead_tree_block(root, block1, blocksize, 0);
if (block2)
@@ -1361,7 +1365,7 @@
eb = read_tree_block(root, block1, blocksize, 0);
free_extent_buffer(eb);
}
- if (block1) {
+ if (block2) {
eb = read_tree_block(root, block2, blocksize, 0);
free_extent_buffer(eb);
}
@@ -1481,12 +1485,15 @@
* of the btree by dropping locks before
* we read.
*/
- btrfs_release_path(NULL, p);
+ btrfs_unlock_up_safe(p, level + 1);
+ btrfs_set_path_blocking(p);
+
if (tmp)
free_extent_buffer(tmp);
if (p->reada)
reada_for_search(root, p, level, slot, key->objectid);
+ btrfs_release_path(NULL, p);
tmp = read_tree_block(root, blocknr, blocksize, gen);
if (tmp)
free_extent_buffer(tmp);