Btrfs: Full back reference support
This patch makes the back reference system to explicit record the
location of parent node for all types of extents. The location of
parent node is placed into the offset field of backref key. Every
time a tree block is balanced, the back references for the affected
lower level extents are updated.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 6f46790..50aea8c 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -125,7 +125,6 @@
u32 nritems;
int ret = 0;
int level;
- struct btrfs_key first_key;
struct btrfs_root *new_root;
new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
@@ -141,18 +140,10 @@
level = btrfs_header_level(buf);
nritems = btrfs_header_nritems(buf);
- if (nritems) {
- if (level == 0)
- btrfs_item_key_to_cpu(buf, &first_key, 0);
- else
- btrfs_node_key_to_cpu(buf, &first_key, 0);
- } else {
- first_key.objectid = 0;
- }
- cow = btrfs_alloc_free_block(trans, new_root, buf->len,
- new_root_objectid,
- trans->transid, first_key.objectid,
- level, buf->start, 0);
+
+ cow = btrfs_alloc_free_block(trans, new_root, buf->len, 0,
+ new_root_objectid, trans->transid,
+ level, buf->start, 0);
if (IS_ERR(cow)) {
kfree(new_root);
return PTR_ERR(cow);
@@ -165,7 +156,7 @@
btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
WARN_ON(btrfs_header_generation(buf) > trans->transid);
- ret = btrfs_inc_ref(trans, new_root, buf, 0);
+ ret = btrfs_inc_ref(trans, new_root, buf, cow, NULL);
kfree(new_root);
if (ret)
@@ -184,39 +175,31 @@
u64 search_start, u64 empty_size,
u64 prealloc_dest)
{
- u64 root_gen;
+ u64 parent_start;
struct extent_buffer *cow;
u32 nritems;
int ret = 0;
int different_trans = 0;
int level;
int unlock_orig = 0;
- struct btrfs_key first_key;
if (*cow_ret == buf)
unlock_orig = 1;
WARN_ON(!btrfs_tree_locked(buf));
- if (root->ref_cows) {
- root_gen = trans->transid;
- } else {
- root_gen = 0;
- }
+ if (parent)
+ parent_start = parent->start;
+ else
+ parent_start = 0;
+
WARN_ON(root->ref_cows && trans->transid !=
root->fs_info->running_transaction->transid);
WARN_ON(root->ref_cows && trans->transid != root->last_trans);
level = btrfs_header_level(buf);
nritems = btrfs_header_nritems(buf);
- if (nritems) {
- if (level == 0)
- btrfs_item_key_to_cpu(buf, &first_key, 0);
- else
- btrfs_node_key_to_cpu(buf, &first_key, 0);
- } else {
- first_key.objectid = 0;
- }
+
if (prealloc_dest) {
struct btrfs_key ins;
@@ -224,19 +207,19 @@
ins.offset = buf->len;
ins.type = BTRFS_EXTENT_ITEM_KEY;
- ret = btrfs_alloc_reserved_extent(trans, root,
+ ret = btrfs_alloc_reserved_extent(trans, root, parent_start,
root->root_key.objectid,
- root_gen, level,
- first_key.objectid,
+ trans->transid, level, 0,
&ins);
BUG_ON(ret);
cow = btrfs_init_new_buffer(trans, root, prealloc_dest,
buf->len);
} else {
cow = btrfs_alloc_free_block(trans, root, buf->len,
+ parent_start,
root->root_key.objectid,
- root_gen, first_key.objectid,
- level, search_start, empty_size);
+ trans->transid, level,
+ search_start, empty_size);
}
if (IS_ERR(cow))
return PTR_ERR(cow);
@@ -249,17 +232,23 @@
WARN_ON(btrfs_header_generation(buf) > trans->transid);
if (btrfs_header_generation(buf) != trans->transid) {
+ u32 nr_extents;
different_trans = 1;
- ret = btrfs_inc_ref(trans, root, buf, 1);
+ ret = btrfs_inc_ref(trans, root, buf, cow, &nr_extents);
if (ret)
return ret;
+
+ ret = btrfs_cache_ref(trans, root, buf, nr_extents);
+ WARN_ON(ret);
} else {
+ ret = btrfs_update_ref(trans, root, buf, cow, 0, nritems);
+ if (ret)
+ return ret;
clean_tree_block(trans, root, buf);
}
if (buf == root->node) {
WARN_ON(parent && parent != buf);
- root_gen = btrfs_header_generation(buf);
spin_lock(&root->node_lock);
root->node = cow;
@@ -268,13 +257,14 @@
if (buf != root->commit_root) {
btrfs_free_extent(trans, root, buf->start,
- buf->len, root->root_key.objectid,
- root_gen, 0, 0, 1);
+ buf->len, buf->start,
+ root->root_key.objectid,
+ btrfs_header_generation(buf),
+ 0, 0, 1);
}
free_extent_buffer(buf);
add_root_to_dirty_list(root);
} else {
- root_gen = btrfs_header_generation(parent);
btrfs_set_node_blockptr(parent, parent_slot,
cow->start);
WARN_ON(trans->transid == 0);
@@ -283,8 +273,8 @@
btrfs_mark_buffer_dirty(parent);
WARN_ON(btrfs_header_generation(parent) != trans->transid);
btrfs_free_extent(trans, root, buf->start, buf->len,
- btrfs_header_owner(parent), root_gen,
- 0, 0, 1);
+ parent_start, btrfs_header_owner(parent),
+ btrfs_header_generation(parent), 0, 0, 1);
}
if (unlock_orig)
btrfs_tree_unlock(buf);
@@ -831,6 +821,12 @@
root->node = child;
spin_unlock(&root->node_lock);
+ ret = btrfs_update_extent_ref(trans, root, child->start,
+ mid->start, child->start,
+ root->root_key.objectid,
+ trans->transid, level - 1, 0);
+ BUG_ON(ret);
+
add_root_to_dirty_list(root);
btrfs_tree_unlock(child);
path->locks[level] = 0;
@@ -840,7 +836,7 @@
/* once for the path */
free_extent_buffer(mid);
ret = btrfs_free_extent(trans, root, mid->start, mid->len,
- root->root_key.objectid,
+ mid->start, root->root_key.objectid,
btrfs_header_generation(mid), 0, 0, 1);
/* once for the root ptr */
free_extent_buffer(mid);
@@ -905,7 +901,7 @@
if (wret)
ret = wret;
wret = btrfs_free_extent(trans, root, bytenr,
- blocksize,
+ blocksize, parent->start,
btrfs_header_owner(parent),
generation, 0, 0, 1);
if (wret)
@@ -954,6 +950,7 @@
if (wret)
ret = wret;
wret = btrfs_free_extent(trans, root, bytenr, blocksize,
+ parent->start,
btrfs_header_owner(parent),
root_gen, 0, 0, 1);
if (wret)
@@ -1500,6 +1497,41 @@
}
/*
+ * update item key.
+ *
+ * This function isn't completely safe. It's the caller's responsibility
+ * that the new key won't break the order
+ */
+int btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, struct btrfs_path *path,
+ struct btrfs_key *new_key)
+{
+ struct btrfs_disk_key disk_key;
+ struct extent_buffer *eb;
+ int slot;
+
+ eb = path->nodes[0];
+ slot = path->slots[0];
+ if (slot > 0) {
+ btrfs_item_key(eb, &disk_key, slot - 1);
+ if (comp_keys(&disk_key, new_key) >= 0)
+ return -1;
+ }
+ if (slot < btrfs_header_nritems(eb) - 1) {
+ btrfs_item_key(eb, &disk_key, slot + 1);
+ if (comp_keys(&disk_key, new_key) <= 0)
+ return -1;
+ }
+
+ btrfs_cpu_key_to_disk(&disk_key, new_key);
+ btrfs_set_item_key(eb, &disk_key, slot);
+ btrfs_mark_buffer_dirty(eb);
+ if (slot == 0)
+ fixup_low_keys(trans, root, path, &disk_key, 1);
+ return 0;
+}
+
+/*
* try to push data from one node into the next node left in the
* tree.
*
@@ -1558,6 +1590,10 @@
btrfs_set_header_nritems(dst, dst_nritems + push_items);
btrfs_mark_buffer_dirty(src);
btrfs_mark_buffer_dirty(dst);
+
+ ret = btrfs_update_ref(trans, root, src, dst, dst_nritems, push_items);
+ BUG_ON(ret);
+
return ret;
}
@@ -1619,6 +1655,10 @@
btrfs_mark_buffer_dirty(src);
btrfs_mark_buffer_dirty(dst);
+
+ ret = btrfs_update_ref(trans, root, src, dst, 0, push_items);
+ BUG_ON(ret);
+
return ret;
}
@@ -1633,30 +1673,24 @@
struct btrfs_root *root,
struct btrfs_path *path, int level)
{
- u64 root_gen;
u64 lower_gen;
struct extent_buffer *lower;
struct extent_buffer *c;
struct extent_buffer *old;
struct btrfs_disk_key lower_key;
+ int ret;
BUG_ON(path->nodes[level]);
BUG_ON(path->nodes[level-1] != root->node);
- if (root->ref_cows)
- root_gen = trans->transid;
- else
- root_gen = 0;
-
lower = path->nodes[level-1];
if (level == 1)
btrfs_item_key(lower, &lower_key, 0);
else
btrfs_node_key(lower, &lower_key, 0);
- c = btrfs_alloc_free_block(trans, root, root->nodesize,
- root->root_key.objectid,
- root_gen, le64_to_cpu(lower_key.objectid),
+ c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
+ root->root_key.objectid, trans->transid,
level, root->node->start, 0);
if (IS_ERR(c))
return PTR_ERR(c);
@@ -1679,7 +1713,7 @@
btrfs_set_node_key(c, &lower_key, 0);
btrfs_set_node_blockptr(c, 0, lower->start);
lower_gen = btrfs_header_generation(lower);
- WARN_ON(lower_gen == 0);
+ WARN_ON(lower_gen != trans->transid);
btrfs_set_node_ptr_generation(c, 0, lower_gen);
@@ -1690,6 +1724,12 @@
root->node = c;
spin_unlock(&root->node_lock);
+ ret = btrfs_update_extent_ref(trans, root, lower->start,
+ lower->start, c->start,
+ root->root_key.objectid,
+ trans->transid, level - 1, 0);
+ BUG_ON(ret);
+
/* the super has an extra ref to root->node */
free_extent_buffer(old);
@@ -1698,20 +1738,6 @@
path->nodes[level] = c;
path->locks[level] = 1;
path->slots[level] = 0;
-
- if (root->ref_cows && lower_gen != trans->transid) {
- struct btrfs_path *back_path = btrfs_alloc_path();
- int ret;
- mutex_lock(&root->fs_info->alloc_mutex);
- ret = btrfs_insert_extent_backref(trans,
- root->fs_info->extent_root,
- path, lower->start,
- root->root_key.objectid,
- trans->transid, 0, 0);
- BUG_ON(ret);
- mutex_unlock(&root->fs_info->alloc_mutex);
- btrfs_free_path(back_path);
- }
return 0;
}
@@ -1766,7 +1792,6 @@
struct btrfs_root *root,
struct btrfs_path *path, int level)
{
- u64 root_gen;
struct extent_buffer *c;
struct extent_buffer *split;
struct btrfs_disk_key disk_key;
@@ -1793,17 +1818,11 @@
}
c_nritems = btrfs_header_nritems(c);
- if (root->ref_cows)
- root_gen = trans->transid;
- else
- root_gen = 0;
- btrfs_node_key(c, &disk_key, 0);
split = btrfs_alloc_free_block(trans, root, root->nodesize,
- root->root_key.objectid,
- root_gen,
- btrfs_disk_key_objectid(&disk_key),
- level, c->start, 0);
+ path->nodes[level + 1]->start,
+ root->root_key.objectid,
+ trans->transid, level, c->start, 0);
if (IS_ERR(split))
return PTR_ERR(split);
@@ -1840,6 +1859,9 @@
if (wret)
ret = wret;
+ ret = btrfs_update_ref(trans, root, c, split, 0, c_nritems - mid);
+ BUG_ON(ret);
+
if (path->slots[level] >= mid) {
path->slots[level] -= mid;
btrfs_tree_unlock(c);
@@ -1955,10 +1977,23 @@
else
nr = 1;
+ if (path->slots[0] >= left_nritems)
+ push_space += data_size + sizeof(*item);
+
i = left_nritems - 1;
while (i >= nr) {
item = btrfs_item_nr(left, i);
+ if (!empty && push_items > 0) {
+ if (path->slots[0] > i)
+ break;
+ if (path->slots[0] == i) {
+ int space = btrfs_leaf_free_space(root, left);
+ if (space + push_space * 2 > free_space)
+ break;
+ }
+ }
+
if (path->slots[0] == i)
push_space += data_size + sizeof(*item);
@@ -1973,6 +2008,7 @@
this_item_size = btrfs_item_size(left, item);
if (this_item_size + sizeof(*item) + push_space > free_space)
break;
+
push_items++;
push_space += this_item_size + sizeof(*item);
if (i == 0)
@@ -2046,6 +2082,9 @@
btrfs_mark_buffer_dirty(left);
btrfs_mark_buffer_dirty(right);
+ ret = btrfs_update_ref(trans, root, left, right, 0, push_items);
+ BUG_ON(ret);
+
btrfs_item_key(right, &disk_key, 0);
btrfs_set_node_key(upper, &disk_key, slot + 1);
btrfs_mark_buffer_dirty(upper);
@@ -2147,6 +2186,16 @@
KM_USER1);
}
+ if (!empty && push_items > 0) {
+ if (path->slots[0] < i)
+ break;
+ if (path->slots[0] == i) {
+ int space = btrfs_leaf_free_space(root, right);
+ if (space + push_space * 2 > free_space)
+ break;
+ }
+ }
+
if (path->slots[0] == i)
push_space += data_size + sizeof(*item);
@@ -2255,6 +2304,10 @@
if (right_nritems)
btrfs_mark_buffer_dirty(right);
+ ret = btrfs_update_ref(trans, root, right, left,
+ old_left_nritems, push_items);
+ BUG_ON(ret);
+
btrfs_item_key(right, &disk_key, 0);
wret = fixup_low_keys(trans, root, path, &disk_key, 1);
if (wret)
@@ -2294,7 +2347,6 @@
struct btrfs_path *path, int data_size,
int extend)
{
- u64 root_gen;
struct extent_buffer *l;
u32 nritems;
int mid;
@@ -2313,11 +2365,6 @@
if (extend)
space_needed = data_size;
- if (root->ref_cows)
- root_gen = trans->transid;
- else
- root_gen = 0;
-
/* first try to make some room by pushing left and right */
if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
wret = push_leaf_right(trans, root, path, data_size, 0);
@@ -2348,13 +2395,10 @@
nritems = btrfs_header_nritems(l);
mid = (nritems + 1)/ 2;
- btrfs_item_key(l, &disk_key, 0);
-
right = btrfs_alloc_free_block(trans, root, root->leafsize,
- root->root_key.objectid,
- root_gen,
- le64_to_cpu(disk_key.objectid),
- 0, l->start, 0);
+ path->nodes[1]->start,
+ root->root_key.objectid,
+ trans->transid, 0, l->start, 0);
if (IS_ERR(right)) {
BUG_ON(1);
return PTR_ERR(right);
@@ -2485,6 +2529,9 @@
btrfs_mark_buffer_dirty(l);
BUG_ON(path->slots[0] != slot);
+ ret = btrfs_update_ref(trans, root, l, right, 0, nritems);
+ BUG_ON(ret);
+
if (mid <= slot) {
btrfs_tree_unlock(path->nodes[0]);
free_extent_buffer(path->nodes[0]);
@@ -2956,6 +3003,7 @@
ret = wret;
wret = btrfs_free_extent(trans, root,
leaf->start, leaf->len,
+ path->nodes[1]->start,
btrfs_header_owner(path->nodes[1]),
root_gen, 0, 0, 1);
if (wret)
@@ -3007,7 +3055,7 @@
free_extent_buffer(leaf);
wret = btrfs_free_extent(trans, root, bytenr,
- blocksize,
+ blocksize, path->nodes[1]->start,
btrfs_header_owner(path->nodes[1]),
root_gen, 0, 0, 1);
if (wret)