Btrfs: Online btree defragmentation fixes
The btree defragger wasn't making forward progress because the new key wasn't
being saved by the btrfs_search_forward function.
This also disables the automatic btree defrag, it wasn't scaling well to
huge filesystems. The auto-defrag needs to be done differently.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 7f4cc2b..0cb80f3 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -63,10 +63,9 @@
void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
{
int i;
- int keep = p->keep_locks;
- int skip = p->skip_locking;
for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
+ p->slots[i] = 0;
if (!p->nodes[i])
continue;
if (p->locks[i]) {
@@ -74,10 +73,8 @@
p->locks[i] = 0;
}
free_extent_buffer(p->nodes[i]);
+ p->nodes[i] = NULL;
}
- memset(p, 0, sizeof(*p));
- p->keep_locks = keep;
- p->skip_locking = skip;
}
struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
@@ -463,8 +460,6 @@
search_start = cur->start;
last_block = cur->start;
*last_ret = search_start;
- if (parent_level == 1)
- btrfs_clear_buffer_defrag(cur);
btrfs_tree_unlock(cur);
free_extent_buffer(cur);
}
@@ -2969,8 +2964,138 @@
return 1;
}
+/*
+ * A helper function to walk down the tree starting at min_key, and looking
+ * for nodes or leaves that are either in cache or have a minimum
+ * transaction id. This is used by the btree defrag code, but could
+ * also be used to search for blocks that have changed since a given
+ * transaction id.
+ *
+ * This does not cow, but it does stuff the starting key it finds back
+ * into min_key, so you can call btrfs_search_slot with cow=1 on the
+ * key and get a writable path.
+ *
+ * This does lock as it descends, and path->keep_locks should be set
+ * to 1 by the caller.
+ *
+ * This honors path->lowest_level to prevent descent past a given level
+ * of the tree.
+ *
+ * returns zero if something useful was found, < 0 on error and 1 if there
+ * was nothing in the tree that matched the search criteria.
+ */
+int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
+ struct btrfs_path *path, int cache_only,
+ u64 min_trans)
+{
+ struct extent_buffer *cur;
+ struct btrfs_key found_key;
+ int slot;
+ u32 nritems;
+ int level;
+ int ret = 1;
+
+again:
+ cur = btrfs_lock_root_node(root);
+ level = btrfs_header_level(cur);
+ path->nodes[level] = cur;
+ path->locks[level] = 1;
+
+ if (btrfs_header_generation(cur) < min_trans) {
+ ret = 1;
+ goto out;
+ }
+ while(1) {
+ nritems = btrfs_header_nritems(cur);
+ level = btrfs_header_level(cur);
+ bin_search(cur, min_key, level, &slot);
+
+ /* at level = 0, we're done, setup the path and exit */
+ if (level == 0) {
+ ret = 0;
+ path->slots[level] = slot;
+ btrfs_item_key_to_cpu(cur, &found_key, slot);
+ goto out;
+ }
+ /*
+ * check this node pointer against the cache_only and
+ * min_trans parameters. If it isn't in cache or is too
+ * old, skip to the next one.
+ */
+ while(slot < nritems) {
+ u64 blockptr;
+ u64 gen;
+ struct extent_buffer *tmp;
+ blockptr = btrfs_node_blockptr(cur, slot);
+ gen = btrfs_node_ptr_generation(cur, slot);
+ if (gen < min_trans) {
+ slot++;
+ continue;
+ }
+ if (!cache_only)
+ break;
+
+ tmp = btrfs_find_tree_block(root, blockptr,
+ btrfs_level_size(root, level - 1));
+
+ if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
+ free_extent_buffer(tmp);
+ break;
+ }
+ if (tmp)
+ free_extent_buffer(tmp);
+ slot++;
+ }
+ /*
+ * we didn't find a candidate key in this node, walk forward
+ * and find another one
+ */
+ if (slot >= nritems) {
+ ret = btrfs_find_next_key(root, path, min_key, level,
+ cache_only, min_trans);
+ if (ret == 0) {
+ btrfs_release_path(root, path);
+ goto again;
+ } else {
+ goto out;
+ }
+ }
+ /* save our key for returning back */
+ btrfs_node_key_to_cpu(cur, &found_key, slot);
+ path->slots[level] = slot;
+ if (level == path->lowest_level) {
+ ret = 0;
+ unlock_up(path, level, 1);
+ goto out;
+ }
+ cur = read_node_slot(root, cur, slot);
+
+ btrfs_tree_lock(cur);
+ path->locks[level - 1] = 1;
+ path->nodes[level - 1] = cur;
+ unlock_up(path, level, 1);
+ }
+out:
+ if (ret == 0)
+ memcpy(min_key, &found_key, sizeof(found_key));
+ return ret;
+}
+
+/*
+ * this is similar to btrfs_next_leaf, but does not try to preserve
+ * and fixup the path. It looks for and returns the next key in the
+ * tree based on the current path and the cache_only and min_trans
+ * parameters.
+ *
+ * 0 is returned if another key is found, < 0 if there are any errors
+ * and 1 is returned if there are no higher keys in the tree
+ *
+ * path->keep_locks should be set to 1 on the search made before
+ * calling this function.
+ */
int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
- struct btrfs_key *key, int lowest_level)
+ struct btrfs_key *key, int lowest_level,
+ int cache_only, u64 min_trans)
{
int level = lowest_level;
int slot;
@@ -2982,6 +3107,7 @@
slot = path->slots[level] + 1;
c = path->nodes[level];
+next:
if (slot >= btrfs_header_nritems(c)) {
level++;
if (level == BTRFS_MAX_LEVEL) {
@@ -2991,8 +3117,28 @@
}
if (level == 0)
btrfs_item_key_to_cpu(c, key, slot);
- else
+ else {
+ u64 blockptr = btrfs_node_blockptr(c, slot);
+ u64 gen = btrfs_node_ptr_generation(c, slot);
+
+ if (cache_only) {
+ struct extent_buffer *cur;
+ cur = btrfs_find_tree_block(root, blockptr,
+ btrfs_level_size(root, level - 1));
+ if (!cur || !btrfs_buffer_uptodate(cur, gen)) {
+ slot++;
+ if (cur)
+ free_extent_buffer(cur);
+ goto next;
+ }
+ free_extent_buffer(cur);
+ }
+ if (gen < min_trans) {
+ slot++;
+ goto next;
+ }
btrfs_node_key_to_cpu(c, key, slot);
+ }
return 0;
}
return 1;
@@ -3095,6 +3241,12 @@
return 0;
}
+/*
+ * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
+ * searching until it gets past min_objectid or finds an item of 'type'
+ *
+ * returns 0 if something is found, 1 if nothing was found and < 0 on error
+ */
int btrfs_previous_item(struct btrfs_root *root,
struct btrfs_path *path, u64 min_objectid,
int type)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ca8e6f1..a287964 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -609,6 +609,7 @@
u64 last_inode_alloc;
int ref_cows;
int track_dirty;
+ u64 defrag_trans_start;
struct btrfs_key defrag_progress;
struct btrfs_key defrag_max;
int defrag_running;
@@ -1412,7 +1413,11 @@
struct extent_buffer *btrfs_root_node(struct btrfs_root *root);
struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
- struct btrfs_key *key, int lowest_level);
+ struct btrfs_key *key, int lowest_level,
+ int cache_only, u64 min_trans);
+int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
+ struct btrfs_path *path, int cache_only,
+ u64 min_trans);
int btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 31ca9f8..4cdc0b6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -295,7 +295,6 @@
ret = btree_read_extent_buffer_pages(root, eb, start + PAGE_CACHE_SIZE,
btrfs_header_generation(eb));
BUG_ON(ret);
- btrfs_clear_buffer_defrag(eb);
found_start = btrfs_header_bytenr(eb);
if (found_start != start) {
printk("warning: eb start incorrect %Lu buffer %Lu len %lu\n",
@@ -355,7 +354,6 @@
}
eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
- btrfs_clear_buffer_defrag(eb);
found_start = btrfs_header_bytenr(eb);
if (found_start != start) {
ret = -EIO;
@@ -736,6 +734,7 @@
memset(&root->root_item, 0, sizeof(root->root_item));
memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
memset(&root->root_kobj, 0, sizeof(root->root_kobj));
+ root->defrag_trans_start = fs_info->generation;
init_completion(&root->kobj_unregister);
root->defrag_running = 0;
root->defrag_level = 0;
@@ -1168,7 +1167,6 @@
goto sleep;
}
mutex_unlock(&root->fs_info->trans_mutex);
- btrfs_defrag_dirty_roots(root->fs_info);
trans = btrfs_start_transaction(root, 1);
ret = btrfs_commit_transaction(trans, root);
sleep:
@@ -1434,12 +1432,12 @@
tree_root,
"btrfs-transaction");
if (!fs_info->transaction_kthread)
- goto fail_trans_kthread;
+ goto fail_cleaner;
return tree_root;
-fail_trans_kthread:
+fail_cleaner:
kthread_stop(fs_info->cleaner_kthread);
fail_extent_root:
free_extent_buffer(extent_root->node);
@@ -1662,7 +1660,6 @@
kthread_stop(root->fs_info->transaction_kthread);
kthread_stop(root->fs_info->cleaner_kthread);
- btrfs_defrag_dirty_roots(root->fs_info);
btrfs_clean_old_snapshots(root);
trans = btrfs_start_transaction(root, 1);
ret = btrfs_commit_transaction(trans, root);
@@ -1794,58 +1791,6 @@
return;
}
-void btrfs_set_buffer_defrag(struct extent_buffer *buf)
-{
- struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
- struct inode *btree_inode = root->fs_info->btree_inode;
- set_extent_bits(&BTRFS_I(btree_inode)->io_tree, buf->start,
- buf->start + buf->len - 1, EXTENT_DEFRAG, GFP_NOFS);
-}
-
-void btrfs_set_buffer_defrag_done(struct extent_buffer *buf)
-{
- struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
- struct inode *btree_inode = root->fs_info->btree_inode;
- set_extent_bits(&BTRFS_I(btree_inode)->io_tree, buf->start,
- buf->start + buf->len - 1, EXTENT_DEFRAG_DONE,
- GFP_NOFS);
-}
-
-int btrfs_buffer_defrag(struct extent_buffer *buf)
-{
- struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
- struct inode *btree_inode = root->fs_info->btree_inode;
- return test_range_bit(&BTRFS_I(btree_inode)->io_tree,
- buf->start, buf->start + buf->len - 1, EXTENT_DEFRAG, 0);
-}
-
-int btrfs_buffer_defrag_done(struct extent_buffer *buf)
-{
- struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
- struct inode *btree_inode = root->fs_info->btree_inode;
- return test_range_bit(&BTRFS_I(btree_inode)->io_tree,
- buf->start, buf->start + buf->len - 1,
- EXTENT_DEFRAG_DONE, 0);
-}
-
-int btrfs_clear_buffer_defrag_done(struct extent_buffer *buf)
-{
- struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
- struct inode *btree_inode = root->fs_info->btree_inode;
- return clear_extent_bits(&BTRFS_I(btree_inode)->io_tree,
- buf->start, buf->start + buf->len - 1,
- EXTENT_DEFRAG_DONE, GFP_NOFS);
-}
-
-int btrfs_clear_buffer_defrag(struct extent_buffer *buf)
-{
- struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
- struct inode *btree_inode = root->fs_info->btree_inode;
- return clear_extent_bits(&BTRFS_I(btree_inode)->io_tree,
- buf->start, buf->start + buf->len - 1,
- EXTENT_DEFRAG, GFP_NOFS);
-}
-
int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
{
struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index deff6b4..353c3c5 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -61,12 +61,6 @@
int btrfs_set_buffer_uptodate(struct extent_buffer *buf);
int wait_on_tree_block_writeback(struct btrfs_root *root,
struct extent_buffer *buf);
-void btrfs_set_buffer_defrag(struct extent_buffer *buf);
-void btrfs_set_buffer_defrag_done(struct extent_buffer *buf);
-int btrfs_buffer_defrag(struct extent_buffer *buf);
-int btrfs_buffer_defrag_done(struct extent_buffer *buf);
-int btrfs_clear_buffer_defrag(struct extent_buffer *buf);
-int btrfs_clear_buffer_defrag_done(struct extent_buffer *buf);
int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid);
u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len);
void btrfs_csum_final(u32 crc, char *result);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index dc3c03c..5e0857f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2095,8 +2095,6 @@
set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
buf->start + buf->len - 1, GFP_NOFS);
- if (!btrfs_test_opt(root, SSD))
- btrfs_set_buffer_defrag(buf);
trans->blocks_used++;
return buf;
}
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 726d687..5e28cf5 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -365,7 +365,6 @@
return 0;
}
btrfs_clean_old_snapshots(root);
- btrfs_defrag_dirty_roots(root->fs_info);
trans = btrfs_start_transaction(root, 1);
ret = btrfs_commit_transaction(trans, root);
sb->s_dirt = 0;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 8e909cb9..98f422d 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -30,7 +30,6 @@
extern struct kmem_cache *btrfs_transaction_cachep;
#define BTRFS_ROOT_TRANS_TAG 0
-#define BTRFS_ROOT_DEFRAG_TAG 1
static noinline void put_transaction(struct btrfs_transaction *transaction)
{
@@ -92,9 +91,6 @@
radix_tree_tag_set(&root->fs_info->fs_roots_radix,
(unsigned long)root->root_key.objectid,
BTRFS_ROOT_TRANS_TAG);
- radix_tree_tag_set(&root->fs_info->fs_roots_radix,
- (unsigned long)root->root_key.objectid,
- BTRFS_ROOT_DEFRAG_TAG);
root->commit_root = btrfs_root_node(root);
} else {
WARN_ON(1);
@@ -403,44 +399,15 @@
cond_resched();
trans = btrfs_start_transaction(root, 1);
- if (ret != -EAGAIN)
+ if (root->fs_info->closing || ret != -EAGAIN)
break;
}
root->defrag_running = 0;
smp_mb();
- radix_tree_tag_clear(&info->fs_roots_radix,
- (unsigned long)root->root_key.objectid,
- BTRFS_ROOT_DEFRAG_TAG);
btrfs_end_transaction(trans, root);
return 0;
}
-int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info)
-{
- struct btrfs_root *gang[1];
- struct btrfs_root *root;
- int i;
- int ret;
- int err = 0;
- u64 last = 0;
-
- while(1) {
- ret = radix_tree_gang_lookup_tag(&info->fs_roots_radix,
- (void **)gang, last,
- ARRAY_SIZE(gang),
- BTRFS_ROOT_DEFRAG_TAG);
- if (ret == 0)
- break;
- for (i = 0; i < ret; i++) {
- root = gang[i];
- last = root->root_key.objectid + 1;
- btrfs_defrag_root(root, 1);
- }
- }
- btrfs_defrag_root(info->extent_root, 1);
- return err;
-}
-
static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
struct list_head *list)
{
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index e1e5a06..9ccd5a5 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -84,7 +84,6 @@
int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest,
struct list_head *dead_list);
-int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info);
int btrfs_defrag_root(struct btrfs_root *root, int cacheonly);
int btrfs_clean_old_snapshots(struct btrfs_root *root);
int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
index b17693f..cc2650b 100644
--- a/fs/btrfs/tree-defrag.c
+++ b/fs/btrfs/tree-defrag.c
@@ -32,10 +32,13 @@
int wret;
int level;
int orig_level;
- int i;
int is_extent = 0;
int next_key_ret = 0;
u64 last_ret = 0;
+ u64 min_trans = 0;
+
+ if (cache_only)
+ goto out;
if (root->fs_info->extent_root == root) {
/*
@@ -43,10 +46,6 @@
* we can't defrag the extent root without deadlock
*/
goto out;
-#if 0
- mutex_lock(&root->fs_info->alloc_mutex);
- is_extent = 1;
-#endif
}
if (root->ref_cows == 0 && !is_extent)
@@ -84,6 +83,17 @@
path->lowest_level = 1;
path->keep_locks = 1;
+ if (cache_only)
+ min_trans = root->defrag_trans_start;
+
+ ret = btrfs_search_forward(root, &key, path, cache_only, min_trans);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ ret = 0;
+ goto out;
+ }
+ btrfs_release_path(root, path);
wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
if (wret < 0) {
@@ -95,7 +105,8 @@
goto out;
}
path->slots[1] = btrfs_header_nritems(path->nodes[1]);
- next_key_ret = btrfs_find_next_key(root, path, &key, 1);
+ next_key_ret = btrfs_find_next_key(root, path, &key, 1, cache_only,
+ min_trans);
ret = btrfs_realloc_node(trans, root,
path->nodes[1], 0,
cache_only, &last_ret,
@@ -106,19 +117,9 @@
ret = -EAGAIN;
}
- for (i = 1; i < BTRFS_MAX_LEVEL; i++) {
- if (path->locks[i]) {
- btrfs_tree_unlock(path->nodes[i]);
- path->locks[i] = 0;
- }
- if (path->nodes[i]) {
- free_extent_buffer(path->nodes[i]);
- path->nodes[i] = NULL;
- }
- }
+ btrfs_release_path(root, path);
if (is_extent)
btrfs_extent_post_op(trans, root);
-
out:
if (is_extent)
mutex_unlock(&root->fs_info->alloc_mutex);
@@ -138,6 +139,7 @@
if (ret != -EAGAIN) {
memset(&root->defrag_progress, 0,
sizeof(root->defrag_progress));
+ root->defrag_trans_start = trans->transid;
}
return ret;
}