Btrfs: Simplify the logic in alloc_extent_buffer() for existing extent buffer case
alloc_extent_buffer() uses radix_tree_lookup() when radix_tree_insert() fails with EEXIST. That part of the code is very similar to the code in find_extent_buffer(). This patch replaces radix_tree_lookup() and surrounding code in alloc_extent_buffer() with find_extent_buffer(). Note that radix_tree_lookup() does not need to be protected by tree->buffer_lock. It is protected by eb->refs. While at it, this patch - changes the other usage of radix_tree_lookup() in alloc_extent_buffer() with find_extent_buffer() to reduce redundancy. - removes the unused argument 'len' to find_extent_buffer(). Signed-Off-by: Chandra Seetharaman <sekharan@us.ibm.com> Reviewed-by: Zach Brown <zab@redhat.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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@ -1104,8 +1104,7 @@ struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
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{
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struct inode *btree_inode = root->fs_info->btree_inode;
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struct extent_buffer *eb;
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eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
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bytenr, blocksize);
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eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree, bytenr);
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return eb;
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}
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@ -4486,6 +4486,23 @@ static void mark_extent_buffer_accessed(struct extent_buffer *eb)
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}
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}
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struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
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u64 start)
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{
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struct extent_buffer *eb;
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rcu_read_lock();
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eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
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if (eb && atomic_inc_not_zero(&eb->refs)) {
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rcu_read_unlock();
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mark_extent_buffer_accessed(eb);
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return eb;
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}
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rcu_read_unlock();
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return NULL;
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}
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struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
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u64 start, unsigned long len)
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{
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@ -4499,14 +4516,10 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
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int uptodate = 1;
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int ret;
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rcu_read_lock();
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eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
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if (eb && atomic_inc_not_zero(&eb->refs)) {
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rcu_read_unlock();
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mark_extent_buffer_accessed(eb);
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eb = find_extent_buffer(tree, start);
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if (eb)
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return eb;
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}
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rcu_read_unlock();
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eb = __alloc_extent_buffer(tree, start, len, GFP_NOFS);
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if (!eb)
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@ -4565,24 +4578,17 @@ again:
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spin_lock(&tree->buffer_lock);
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ret = radix_tree_insert(&tree->buffer, start >> PAGE_CACHE_SHIFT, eb);
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spin_unlock(&tree->buffer_lock);
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radix_tree_preload_end();
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if (ret == -EEXIST) {
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exists = radix_tree_lookup(&tree->buffer,
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start >> PAGE_CACHE_SHIFT);
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if (!atomic_inc_not_zero(&exists->refs)) {
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spin_unlock(&tree->buffer_lock);
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radix_tree_preload_end();
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exists = NULL;
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exists = find_extent_buffer(tree, start);
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if (exists)
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goto free_eb;
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else
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goto again;
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}
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spin_unlock(&tree->buffer_lock);
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radix_tree_preload_end();
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mark_extent_buffer_accessed(exists);
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goto free_eb;
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}
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/* add one reference for the tree */
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check_buffer_tree_ref(eb);
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spin_unlock(&tree->buffer_lock);
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radix_tree_preload_end();
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/*
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* there is a race where release page may have
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@ -4613,23 +4619,6 @@ free_eb:
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return exists;
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}
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struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
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u64 start, unsigned long len)
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{
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struct extent_buffer *eb;
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rcu_read_lock();
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eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
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if (eb && atomic_inc_not_zero(&eb->refs)) {
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rcu_read_unlock();
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mark_extent_buffer_accessed(eb);
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return eb;
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}
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rcu_read_unlock();
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return NULL;
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}
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static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
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{
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struct extent_buffer *eb =
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@ -271,7 +271,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
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struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len);
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struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src);
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struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
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u64 start, unsigned long len);
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u64 start);
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void free_extent_buffer(struct extent_buffer *eb);
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void free_extent_buffer_stale(struct extent_buffer *eb);
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#define WAIT_NONE 0
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