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 <sekha...@us.ibm.com>
Reviewed-by: Zach Brown <z...@redhat.com>
---
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4ae17ed..daa04d2 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1105,8 +1105,7 @@ struct extent_buffer *btrfs_find_tree_block(struct
btrfs_root *root,
{
struct inode *btree_inode = root->fs_info->btree_inode;
struct extent_buffer *eb;
- eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
- bytenr, blocksize);
+ eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree, bytenr);
return eb;
}
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index c09a40d..f45b4e8 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4451,6 +4451,23 @@ static void mark_extent_buffer_accessed(struct
extent_buffer *eb)
}
}
+struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
+ u64 start)
+{
+ struct extent_buffer *eb;
+
+ rcu_read_lock();
+ eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
+ if (eb && atomic_inc_not_zero(&eb->refs)) {
+ rcu_read_unlock();
+ mark_extent_buffer_accessed(eb);
+ return eb;
+ }
+ rcu_read_unlock();
+
+ return NULL;
+}
+
struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
u64 start, unsigned long len)
{
@@ -4464,14 +4481,10 @@ struct extent_buffer *alloc_extent_buffer(struct
extent_io_tree *tree,
int uptodate = 1;
int ret;
- rcu_read_lock();
- eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
- if (eb && atomic_inc_not_zero(&eb->refs)) {
- rcu_read_unlock();
- mark_extent_buffer_accessed(eb);
+
+ eb = find_extent_buffer(tree, start);
+ if (eb)
return eb;
- }
- rcu_read_unlock();
eb = __alloc_extent_buffer(tree, start, len, GFP_NOFS);
if (!eb)
@@ -4530,24 +4543,17 @@ again:
spin_lock(&tree->buffer_lock);
ret = radix_tree_insert(&tree->buffer, start >> PAGE_CACHE_SHIFT, eb);
+ spin_unlock(&tree->buffer_lock);
+ radix_tree_preload_end();
if (ret == -EEXIST) {
- exists = radix_tree_lookup(&tree->buffer,
- start >> PAGE_CACHE_SHIFT);
- if (!atomic_inc_not_zero(&exists->refs)) {
- spin_unlock(&tree->buffer_lock);
- radix_tree_preload_end();
- exists = NULL;
+ exists = find_extent_buffer(tree, start);
+ if (exists)
+ goto free_eb;
+ else
goto again;
- }
- spin_unlock(&tree->buffer_lock);
- radix_tree_preload_end();
- mark_extent_buffer_accessed(exists);
- goto free_eb;
}
/* add one reference for the tree */
check_buffer_tree_ref(eb);
- spin_unlock(&tree->buffer_lock);
- radix_tree_preload_end();
/*
* there is a race where release page may have
@@ -4578,23 +4584,6 @@ free_eb:
return exists;
}
-struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
- u64 start, unsigned long len)
-{
- struct extent_buffer *eb;
-
- rcu_read_lock();
- eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
- if (eb && atomic_inc_not_zero(&eb->refs)) {
- rcu_read_unlock();
- mark_extent_buffer_accessed(eb);
- return eb;
- }
- rcu_read_unlock();
-
- return NULL;
-}
-
static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
{
struct extent_buffer *eb =
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 6dbc645..a4b75af 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -271,7 +271,7 @@ struct extent_buffer *alloc_extent_buffer(struct
extent_io_tree *tree,
struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len);
struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src);
struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
- u64 start, unsigned long len);
+ u64 start);
void free_extent_buffer(struct extent_buffer *eb);
void free_extent_buffer_stale(struct extent_buffer *eb);
#define WAIT_NONE 0
--
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