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Btrfs: break up btrfs_search_slot into smaller pieces
btrfs_search_slot was doing too many things at once. This breaks it up into more reasonable units. Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
parent
04018de5d4
commit
c8c42864f6
221
fs/btrfs/ctree.c
221
fs/btrfs/ctree.c
@ -1244,9 +1244,9 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
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* readahead one full node of leaves, finding things that are close
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* to the block in 'slot', and triggering ra on them.
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*/
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static noinline void reada_for_search(struct btrfs_root *root,
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struct btrfs_path *path,
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int level, int slot, u64 objectid)
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static void reada_for_search(struct btrfs_root *root,
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struct btrfs_path *path,
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int level, int slot, u64 objectid)
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{
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struct extent_buffer *node;
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struct btrfs_disk_key disk_key;
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@ -1446,6 +1446,117 @@ noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
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}
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}
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/*
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* helper function for btrfs_search_slot. The goal is to find a block
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* in cache without setting the path to blocking. If we find the block
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* we return zero and the path is unchanged.
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*
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* If we can't find the block, we set the path blocking and do some
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* reada. -EAGAIN is returned and the search must be repeated.
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*/
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static int
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read_block_for_search(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, struct btrfs_path *p,
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struct extent_buffer **eb_ret, int level, int slot,
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struct btrfs_key *key)
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{
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u64 blocknr;
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u64 gen;
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u32 blocksize;
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struct extent_buffer *b = *eb_ret;
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struct extent_buffer *tmp;
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blocknr = btrfs_node_blockptr(b, slot);
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gen = btrfs_node_ptr_generation(b, slot);
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blocksize = btrfs_level_size(root, level - 1);
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tmp = btrfs_find_tree_block(root, blocknr, blocksize);
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if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
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*eb_ret = tmp;
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return 0;
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}
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/*
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* reduce lock contention at high levels
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* of the btree by dropping locks before
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* we read.
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*/
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btrfs_release_path(NULL, p);
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if (tmp)
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free_extent_buffer(tmp);
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if (p->reada)
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reada_for_search(root, p, level, slot, key->objectid);
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tmp = read_tree_block(root, blocknr, blocksize, gen);
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if (tmp)
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free_extent_buffer(tmp);
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return -EAGAIN;
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}
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/*
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* helper function for btrfs_search_slot. This does all of the checks
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* for node-level blocks and does any balancing required based on
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* the ins_len.
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*
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* If no extra work was required, zero is returned. If we had to
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* drop the path, -EAGAIN is returned and btrfs_search_slot must
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* start over
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*/
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static int
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setup_nodes_for_search(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, struct btrfs_path *p,
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struct extent_buffer *b, int level, int ins_len)
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{
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int ret;
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if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
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BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
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int sret;
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sret = reada_for_balance(root, p, level);
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if (sret)
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goto again;
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btrfs_set_path_blocking(p);
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sret = split_node(trans, root, p, level);
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btrfs_clear_path_blocking(p, NULL);
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BUG_ON(sret > 0);
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if (sret) {
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ret = sret;
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goto done;
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}
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b = p->nodes[level];
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} else if (ins_len < 0 && btrfs_header_nritems(b) <
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BTRFS_NODEPTRS_PER_BLOCK(root) / 4) {
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int sret;
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sret = reada_for_balance(root, p, level);
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if (sret)
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goto again;
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btrfs_set_path_blocking(p);
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sret = balance_level(trans, root, p, level);
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btrfs_clear_path_blocking(p, NULL);
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if (sret) {
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ret = sret;
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goto done;
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}
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b = p->nodes[level];
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if (!b) {
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btrfs_release_path(NULL, p);
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goto again;
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}
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BUG_ON(btrfs_header_nritems(b) == 1);
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}
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return 0;
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again:
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ret = -EAGAIN;
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done:
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return ret;
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}
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/*
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* look for key in the tree. path is filled in with nodes along the way
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* if key is found, we return zero and you can find the item in the leaf
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@ -1464,16 +1575,11 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
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ins_len, int cow)
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{
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struct extent_buffer *b;
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struct extent_buffer *tmp;
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int slot;
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int ret;
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int level;
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int should_reada = p->reada;
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int lowest_unlock = 1;
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int blocksize;
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u8 lowest_level = 0;
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u64 blocknr;
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u64 gen;
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lowest_level = p->lowest_level;
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WARN_ON(lowest_level && ins_len > 0);
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@ -1502,7 +1608,11 @@ again:
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if (cow) {
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int wret;
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/* is a cow on this block not required */
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/*
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* if we don't really need to cow this block
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* then we don't want to set the path blocking,
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* so we test it here
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*/
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if (btrfs_header_generation(b) == trans->transid &&
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btrfs_header_owner(b) == root->root_key.objectid &&
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!btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
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@ -1557,51 +1667,15 @@ cow_done:
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if (ret && slot > 0)
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slot -= 1;
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p->slots[level] = slot;
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if ((p->search_for_split || ins_len > 0) &&
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btrfs_header_nritems(b) >=
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BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
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int sret;
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ret = setup_nodes_for_search(trans, root, p, b, level,
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ins_len);
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if (ret == -EAGAIN)
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goto again;
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else if (ret)
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goto done;
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b = p->nodes[level];
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slot = p->slots[level];
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sret = reada_for_balance(root, p, level);
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if (sret)
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goto again;
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btrfs_set_path_blocking(p);
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sret = split_node(trans, root, p, level);
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btrfs_clear_path_blocking(p, NULL);
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BUG_ON(sret > 0);
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if (sret) {
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ret = sret;
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goto done;
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}
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b = p->nodes[level];
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slot = p->slots[level];
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} else if (ins_len < 0 &&
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btrfs_header_nritems(b) <
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BTRFS_NODEPTRS_PER_BLOCK(root) / 4) {
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int sret;
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sret = reada_for_balance(root, p, level);
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if (sret)
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goto again;
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btrfs_set_path_blocking(p);
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sret = balance_level(trans, root, p, level);
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btrfs_clear_path_blocking(p, NULL);
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if (sret) {
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ret = sret;
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goto done;
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}
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b = p->nodes[level];
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if (!b) {
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btrfs_release_path(NULL, p);
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goto again;
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}
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slot = p->slots[level];
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BUG_ON(btrfs_header_nritems(b) == 1);
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}
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unlock_up(p, level, lowest_unlock);
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/* this is only true while dropping a snapshot */
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@ -1610,44 +1684,11 @@ cow_done:
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goto done;
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}
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blocknr = btrfs_node_blockptr(b, slot);
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gen = btrfs_node_ptr_generation(b, slot);
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blocksize = btrfs_level_size(root, level - 1);
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ret = read_block_for_search(trans, root, p,
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&b, level, slot, key);
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if (ret == -EAGAIN)
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goto again;
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tmp = btrfs_find_tree_block(root, blocknr, blocksize);
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if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
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b = tmp;
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} else {
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/*
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* reduce lock contention at high levels
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* of the btree by dropping locks before
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* we read.
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*/
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if (level > 0) {
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btrfs_release_path(NULL, p);
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if (tmp)
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free_extent_buffer(tmp);
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if (should_reada)
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reada_for_search(root, p,
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level, slot,
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key->objectid);
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tmp = read_tree_block(root, blocknr,
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blocksize, gen);
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if (tmp)
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free_extent_buffer(tmp);
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goto again;
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} else {
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btrfs_set_path_blocking(p);
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if (tmp)
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free_extent_buffer(tmp);
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if (should_reada)
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reada_for_search(root, p,
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level, slot,
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key->objectid);
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b = read_node_slot(root, b, slot);
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}
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}
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if (!p->skip_locking) {
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int lret;
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