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-rw-r--r--fs/btrfs/ctree.c221
1 files changed, 131 insertions, 90 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index dbb7241..271b05e 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1244,9 +1244,9 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
* readahead one full node of leaves, finding things that are close
* to the block in 'slot', and triggering ra on them.
*/
-static noinline void reada_for_search(struct btrfs_root *root,
- struct btrfs_path *path,
- int level, int slot, u64 objectid)
+static void reada_for_search(struct btrfs_root *root,
+ struct btrfs_path *path,
+ int level, int slot, u64 objectid)
{
struct extent_buffer *node;
struct btrfs_disk_key disk_key;
@@ -1447,6 +1447,117 @@ noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
}
/*
+ * helper function for btrfs_search_slot. The goal is to find a block
+ * in cache without setting the path to blocking. If we find the block
+ * we return zero and the path is unchanged.
+ *
+ * If we can't find the block, we set the path blocking and do some
+ * reada. -EAGAIN is returned and the search must be repeated.
+ */
+static int
+read_block_for_search(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, struct btrfs_path *p,
+ struct extent_buffer **eb_ret, int level, int slot,
+ struct btrfs_key *key)
+{
+ u64 blocknr;
+ u64 gen;
+ u32 blocksize;
+ struct extent_buffer *b = *eb_ret;
+ struct extent_buffer *tmp;
+
+ blocknr = btrfs_node_blockptr(b, slot);
+ gen = btrfs_node_ptr_generation(b, slot);
+ blocksize = btrfs_level_size(root, level - 1);
+
+ tmp = btrfs_find_tree_block(root, blocknr, blocksize);
+ if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
+ *eb_ret = tmp;
+ return 0;
+ }
+
+ /*
+ * reduce lock contention at high levels
+ * of the btree by dropping locks before
+ * we read.
+ */
+ btrfs_release_path(NULL, p);
+ if (tmp)
+ free_extent_buffer(tmp);
+ if (p->reada)
+ reada_for_search(root, p, level, slot, key->objectid);
+
+ tmp = read_tree_block(root, blocknr, blocksize, gen);
+ if (tmp)
+ free_extent_buffer(tmp);
+ return -EAGAIN;
+}
+
+/*
+ * helper function for btrfs_search_slot. This does all of the checks
+ * for node-level blocks and does any balancing required based on
+ * the ins_len.
+ *
+ * If no extra work was required, zero is returned. If we had to
+ * drop the path, -EAGAIN is returned and btrfs_search_slot must
+ * start over
+ */
+static int
+setup_nodes_for_search(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, struct btrfs_path *p,
+ struct extent_buffer *b, int level, int ins_len)
+{
+ int ret;
+ if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
+ BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
+ int sret;
+
+ sret = reada_for_balance(root, p, level);
+ if (sret)
+ goto again;
+
+ btrfs_set_path_blocking(p);
+ sret = split_node(trans, root, p, level);
+ btrfs_clear_path_blocking(p, NULL);
+
+ BUG_ON(sret > 0);
+ if (sret) {
+ ret = sret;
+ goto done;
+ }
+ b = p->nodes[level];
+ } else if (ins_len < 0 && btrfs_header_nritems(b) <
+ BTRFS_NODEPTRS_PER_BLOCK(root) / 4) {
+ int sret;
+
+ sret = reada_for_balance(root, p, level);
+ if (sret)
+ goto again;
+
+ btrfs_set_path_blocking(p);
+ sret = balance_level(trans, root, p, level);
+ btrfs_clear_path_blocking(p, NULL);
+
+ if (sret) {
+ ret = sret;
+ goto done;
+ }
+ b = p->nodes[level];
+ if (!b) {
+ btrfs_release_path(NULL, p);
+ goto again;
+ }
+ BUG_ON(btrfs_header_nritems(b) == 1);
+ }
+ return 0;
+
+again:
+ ret = -EAGAIN;
+done:
+ return ret;
+}
+
+/*
* look for key in the tree. path is filled in with nodes along the way
* if key is found, we return zero and you can find the item in the leaf
* level of the path (level 0)
@@ -1464,16 +1575,11 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
ins_len, int cow)
{
struct extent_buffer *b;
- struct extent_buffer *tmp;
int slot;
int ret;
int level;
- int should_reada = p->reada;
int lowest_unlock = 1;
- int blocksize;
u8 lowest_level = 0;
- u64 blocknr;
- u64 gen;
lowest_level = p->lowest_level;
WARN_ON(lowest_level && ins_len > 0);
@@ -1502,7 +1608,11 @@ again:
if (cow) {
int wret;
- /* is a cow on this block not required */
+ /*
+ * if we don't really need to cow this block
+ * then we don't want to set the path blocking,
+ * so we test it here
+ */
if (btrfs_header_generation(b) == trans->transid &&
btrfs_header_owner(b) == root->root_key.objectid &&
!btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
@@ -1557,51 +1667,15 @@ cow_done:
if (ret && slot > 0)
slot -= 1;
p->slots[level] = slot;
- if ((p->search_for_split || ins_len > 0) &&
- btrfs_header_nritems(b) >=
- BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
- int sret;
-
- sret = reada_for_balance(root, p, level);
- if (sret)
- goto again;
-
- btrfs_set_path_blocking(p);
- sret = split_node(trans, root, p, level);
- btrfs_clear_path_blocking(p, NULL);
-
- BUG_ON(sret > 0);
- if (sret) {
- ret = sret;
- goto done;
- }
- b = p->nodes[level];
- slot = p->slots[level];
- } else if (ins_len < 0 &&
- btrfs_header_nritems(b) <
- BTRFS_NODEPTRS_PER_BLOCK(root) / 4) {
- int sret;
-
- sret = reada_for_balance(root, p, level);
- if (sret)
- goto again;
-
- btrfs_set_path_blocking(p);
- sret = balance_level(trans, root, p, level);
- btrfs_clear_path_blocking(p, NULL);
+ ret = setup_nodes_for_search(trans, root, p, b, level,
+ ins_len);
+ if (ret == -EAGAIN)
+ goto again;
+ else if (ret)
+ goto done;
+ b = p->nodes[level];
+ slot = p->slots[level];
- if (sret) {
- ret = sret;
- goto done;
- }
- b = p->nodes[level];
- if (!b) {
- btrfs_release_path(NULL, p);
- goto again;
- }
- slot = p->slots[level];
- BUG_ON(btrfs_header_nritems(b) == 1);
- }
unlock_up(p, level, lowest_unlock);
/* this is only true while dropping a snapshot */
@@ -1610,44 +1684,11 @@ cow_done:
goto done;
}
- blocknr = btrfs_node_blockptr(b, slot);
- gen = btrfs_node_ptr_generation(b, slot);
- blocksize = btrfs_level_size(root, level - 1);
+ ret = read_block_for_search(trans, root, p,
+ &b, level, slot, key);
+ if (ret == -EAGAIN)
+ goto again;
- tmp = btrfs_find_tree_block(root, blocknr, blocksize);
- if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
- b = tmp;
- } else {
- /*
- * reduce lock contention at high levels
- * of the btree by dropping locks before
- * we read.
- */
- if (level > 0) {
- btrfs_release_path(NULL, p);
- if (tmp)
- free_extent_buffer(tmp);
- if (should_reada)
- reada_for_search(root, p,
- level, slot,
- key->objectid);
-
- tmp = read_tree_block(root, blocknr,
- blocksize, gen);
- if (tmp)
- free_extent_buffer(tmp);
- goto again;
- } else {
- btrfs_set_path_blocking(p);
- if (tmp)
- free_extent_buffer(tmp);
- if (should_reada)
- reada_for_search(root, p,
- level, slot,
- key->objectid);
- b = read_node_slot(root, b, slot);
- }
- }
if (!p->skip_locking) {
int lret;
generated by cgit v1.1 at 2024-12-28 06:56:56 +0000