* [PATCH 4/7] btrfs: rename and export read_node_slot
2019-08-23 17:08 [PATCH 0/7] Move some code out of ctree.c and ctree.h David Sterba
` (2 preceding siblings ...)
2019-08-23 17:08 ` [PATCH 3/7] btrfs: move private raid56 definitions from ctree.h David Sterba
@ 2019-08-23 17:08 ` David Sterba
2019-08-27 13:39 ` Johannes Thumshirn
2019-08-23 17:08 ` [PATCH 5/7] btrfs: move functions for tree compare to send.c David Sterba
` (2 subsequent siblings)
6 siblings, 1 reply; 15+ messages in thread
From: David Sterba @ 2019-08-23 17:08 UTC (permalink / raw)
To: linux-btrfs; +Cc: David Sterba
Preparatory work for code that will be moved out of ctree and uses this
function.
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/ctree.c | 22 +++++++++++-----------
fs/btrfs/ctree.h | 3 +++
2 files changed, 14 insertions(+), 11 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index a2f3cd7a619c..3b585f3e4d11 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1792,8 +1792,8 @@ static void root_sub_used(struct btrfs_root *root, u32 size)
/* given a node and slot number, this reads the blocks it points to. The
* extent buffer is returned with a reference taken (but unlocked).
*/
-static noinline struct extent_buffer *read_node_slot(
- struct extent_buffer *parent, int slot)
+struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
+ int slot)
{
int level = btrfs_header_level(parent);
struct extent_buffer *eb;
@@ -1862,7 +1862,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
return 0;
/* promote the child to a root */
- child = read_node_slot(mid, 0);
+ child = btrfs_read_node_slot(mid, 0);
if (IS_ERR(child)) {
ret = PTR_ERR(child);
btrfs_handle_fs_error(fs_info, ret, NULL);
@@ -1902,7 +1902,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
return 0;
- left = read_node_slot(parent, pslot - 1);
+ left = btrfs_read_node_slot(parent, pslot - 1);
if (IS_ERR(left))
left = NULL;
@@ -1917,7 +1917,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
}
}
- right = read_node_slot(parent, pslot + 1);
+ right = btrfs_read_node_slot(parent, pslot + 1);
if (IS_ERR(right))
right = NULL;
@@ -2077,7 +2077,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
if (!parent)
return 1;
- left = read_node_slot(parent, pslot - 1);
+ left = btrfs_read_node_slot(parent, pslot - 1);
if (IS_ERR(left))
left = NULL;
@@ -2129,7 +2129,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
btrfs_tree_unlock(left);
free_extent_buffer(left);
}
- right = read_node_slot(parent, pslot + 1);
+ right = btrfs_read_node_slot(parent, pslot + 1);
if (IS_ERR(right))
right = NULL;
@@ -3783,7 +3783,7 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
btrfs_assert_tree_locked(path->nodes[1]);
- right = read_node_slot(upper, slot + 1);
+ right = btrfs_read_node_slot(upper, slot + 1);
/*
* slot + 1 is not valid or we fail to read the right node,
* no big deal, just return.
@@ -4017,7 +4017,7 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
btrfs_assert_tree_locked(path->nodes[1]);
- left = read_node_slot(path->nodes[1], slot - 1);
+ left = btrfs_read_node_slot(path->nodes[1], slot - 1);
/*
* slot - 1 is not valid or we fail to read the left node,
* no big deal, just return.
@@ -5224,7 +5224,7 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
goto out;
}
btrfs_set_path_blocking(path);
- cur = read_node_slot(cur, slot);
+ cur = btrfs_read_node_slot(cur, slot);
if (IS_ERR(cur)) {
ret = PTR_ERR(cur);
goto out;
@@ -5251,7 +5251,7 @@ static int tree_move_down(struct btrfs_path *path, int *level)
struct extent_buffer *eb;
BUG_ON(*level == 0);
- eb = read_node_slot(path->nodes[*level], path->slots[*level]);
+ eb = btrfs_read_node_slot(path->nodes[*level], path->slots[*level]);
if (IS_ERR(eb))
return PTR_ERR(eb);
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a7291e7dd574..70a80db23ecc 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2586,6 +2586,9 @@ int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
struct btrfs_path *path,
u64 min_trans);
+struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
+ int slot);
+
enum btrfs_compare_tree_result {
BTRFS_COMPARE_TREE_NEW,
BTRFS_COMPARE_TREE_DELETED,
--
2.22.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [PATCH 5/7] btrfs: move functions for tree compare to send.c
2019-08-23 17:08 [PATCH 0/7] Move some code out of ctree.c and ctree.h David Sterba
` (3 preceding siblings ...)
2019-08-23 17:08 ` [PATCH 4/7] btrfs: rename and export read_node_slot David Sterba
@ 2019-08-23 17:08 ` David Sterba
2019-08-27 13:38 ` Johannes Thumshirn
2019-08-23 17:08 ` [PATCH 6/7] btrfs: move struct io_ctl to free-space-cache.h David Sterba
2019-08-23 17:08 ` [PATCH 7/7] btrfs: move dev_stats helpers to volumes.c David Sterba
6 siblings, 1 reply; 15+ messages in thread
From: David Sterba @ 2019-08-23 17:08 UTC (permalink / raw)
To: linux-btrfs; +Cc: David Sterba
Send is the only user of tree_compare, we can move it there along with
the other helpers and definitions.
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/ctree.c | 362 ---------------------------------------------
fs/btrfs/ctree.h | 14 --
fs/btrfs/send.c | 374 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 374 insertions(+), 376 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 3b585f3e4d11..fbf94e28fba8 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -5246,368 +5246,6 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
return ret;
}
-static int tree_move_down(struct btrfs_path *path, int *level)
-{
- struct extent_buffer *eb;
-
- BUG_ON(*level == 0);
- eb = btrfs_read_node_slot(path->nodes[*level], path->slots[*level]);
- if (IS_ERR(eb))
- return PTR_ERR(eb);
-
- path->nodes[*level - 1] = eb;
- path->slots[*level - 1] = 0;
- (*level)--;
- return 0;
-}
-
-static int tree_move_next_or_upnext(struct btrfs_path *path,
- int *level, int root_level)
-{
- int ret = 0;
- int nritems;
- nritems = btrfs_header_nritems(path->nodes[*level]);
-
- path->slots[*level]++;
-
- while (path->slots[*level] >= nritems) {
- if (*level == root_level)
- return -1;
-
- /* move upnext */
- path->slots[*level] = 0;
- free_extent_buffer(path->nodes[*level]);
- path->nodes[*level] = NULL;
- (*level)++;
- path->slots[*level]++;
-
- nritems = btrfs_header_nritems(path->nodes[*level]);
- ret = 1;
- }
- return ret;
-}
-
-/*
- * Returns 1 if it had to move up and next. 0 is returned if it moved only next
- * or down.
- */
-static int tree_advance(struct btrfs_path *path,
- int *level, int root_level,
- int allow_down,
- struct btrfs_key *key)
-{
- int ret;
-
- if (*level == 0 || !allow_down) {
- ret = tree_move_next_or_upnext(path, level, root_level);
- } else {
- ret = tree_move_down(path, level);
- }
- if (ret >= 0) {
- if (*level == 0)
- btrfs_item_key_to_cpu(path->nodes[*level], key,
- path->slots[*level]);
- else
- btrfs_node_key_to_cpu(path->nodes[*level], key,
- path->slots[*level]);
- }
- return ret;
-}
-
-static int tree_compare_item(struct btrfs_path *left_path,
- struct btrfs_path *right_path,
- char *tmp_buf)
-{
- int cmp;
- int len1, len2;
- unsigned long off1, off2;
-
- len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]);
- len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]);
- if (len1 != len2)
- return 1;
-
- off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
- off2 = btrfs_item_ptr_offset(right_path->nodes[0],
- right_path->slots[0]);
-
- read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
-
- cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
- if (cmp)
- return 1;
- return 0;
-}
-
-#define ADVANCE 1
-#define ADVANCE_ONLY_NEXT -1
-
-/*
- * This function compares two trees and calls the provided callback for
- * every changed/new/deleted item it finds.
- * If shared tree blocks are encountered, whole subtrees are skipped, making
- * the compare pretty fast on snapshotted subvolumes.
- *
- * This currently works on commit roots only. As commit roots are read only,
- * we don't do any locking. The commit roots are protected with transactions.
- * Transactions are ended and rejoined when a commit is tried in between.
- *
- * This function checks for modifications done to the trees while comparing.
- * If it detects a change, it aborts immediately.
- */
-int btrfs_compare_trees(struct btrfs_root *left_root,
- struct btrfs_root *right_root,
- btrfs_changed_cb_t changed_cb, void *ctx)
-{
- struct btrfs_fs_info *fs_info = left_root->fs_info;
- int ret;
- int cmp;
- struct btrfs_path *left_path = NULL;
- struct btrfs_path *right_path = NULL;
- struct btrfs_key left_key;
- struct btrfs_key right_key;
- char *tmp_buf = NULL;
- int left_root_level;
- int right_root_level;
- int left_level;
- int right_level;
- int left_end_reached;
- int right_end_reached;
- int advance_left;
- int advance_right;
- u64 left_blockptr;
- u64 right_blockptr;
- u64 left_gen;
- u64 right_gen;
-
- left_path = btrfs_alloc_path();
- if (!left_path) {
- ret = -ENOMEM;
- goto out;
- }
- right_path = btrfs_alloc_path();
- if (!right_path) {
- ret = -ENOMEM;
- goto out;
- }
-
- tmp_buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
- if (!tmp_buf) {
- ret = -ENOMEM;
- goto out;
- }
-
- left_path->search_commit_root = 1;
- left_path->skip_locking = 1;
- right_path->search_commit_root = 1;
- right_path->skip_locking = 1;
-
- /*
- * Strategy: Go to the first items of both trees. Then do
- *
- * If both trees are at level 0
- * Compare keys of current items
- * If left < right treat left item as new, advance left tree
- * and repeat
- * If left > right treat right item as deleted, advance right tree
- * and repeat
- * If left == right do deep compare of items, treat as changed if
- * needed, advance both trees and repeat
- * If both trees are at the same level but not at level 0
- * Compare keys of current nodes/leafs
- * If left < right advance left tree and repeat
- * If left > right advance right tree and repeat
- * If left == right compare blockptrs of the next nodes/leafs
- * If they match advance both trees but stay at the same level
- * and repeat
- * If they don't match advance both trees while allowing to go
- * deeper and repeat
- * If tree levels are different
- * Advance the tree that needs it and repeat
- *
- * Advancing a tree means:
- * If we are at level 0, try to go to the next slot. If that's not
- * possible, go one level up and repeat. Stop when we found a level
- * where we could go to the next slot. We may at this point be on a
- * node or a leaf.
- *
- * If we are not at level 0 and not on shared tree blocks, go one
- * level deeper.
- *
- * If we are not at level 0 and on shared tree blocks, go one slot to
- * the right if possible or go up and right.
- */
-
- down_read(&fs_info->commit_root_sem);
- left_level = btrfs_header_level(left_root->commit_root);
- left_root_level = left_level;
- left_path->nodes[left_level] =
- btrfs_clone_extent_buffer(left_root->commit_root);
- if (!left_path->nodes[left_level]) {
- up_read(&fs_info->commit_root_sem);
- ret = -ENOMEM;
- goto out;
- }
-
- right_level = btrfs_header_level(right_root->commit_root);
- right_root_level = right_level;
- right_path->nodes[right_level] =
- btrfs_clone_extent_buffer(right_root->commit_root);
- if (!right_path->nodes[right_level]) {
- up_read(&fs_info->commit_root_sem);
- ret = -ENOMEM;
- goto out;
- }
- up_read(&fs_info->commit_root_sem);
-
- if (left_level == 0)
- btrfs_item_key_to_cpu(left_path->nodes[left_level],
- &left_key, left_path->slots[left_level]);
- else
- btrfs_node_key_to_cpu(left_path->nodes[left_level],
- &left_key, left_path->slots[left_level]);
- if (right_level == 0)
- btrfs_item_key_to_cpu(right_path->nodes[right_level],
- &right_key, right_path->slots[right_level]);
- else
- btrfs_node_key_to_cpu(right_path->nodes[right_level],
- &right_key, right_path->slots[right_level]);
-
- left_end_reached = right_end_reached = 0;
- advance_left = advance_right = 0;
-
- while (1) {
- if (advance_left && !left_end_reached) {
- ret = tree_advance(left_path, &left_level,
- left_root_level,
- advance_left != ADVANCE_ONLY_NEXT,
- &left_key);
- if (ret == -1)
- left_end_reached = ADVANCE;
- else if (ret < 0)
- goto out;
- advance_left = 0;
- }
- if (advance_right && !right_end_reached) {
- ret = tree_advance(right_path, &right_level,
- right_root_level,
- advance_right != ADVANCE_ONLY_NEXT,
- &right_key);
- if (ret == -1)
- right_end_reached = ADVANCE;
- else if (ret < 0)
- goto out;
- advance_right = 0;
- }
-
- if (left_end_reached && right_end_reached) {
- ret = 0;
- goto out;
- } else if (left_end_reached) {
- if (right_level == 0) {
- ret = changed_cb(left_path, right_path,
- &right_key,
- BTRFS_COMPARE_TREE_DELETED,
- ctx);
- if (ret < 0)
- goto out;
- }
- advance_right = ADVANCE;
- continue;
- } else if (right_end_reached) {
- if (left_level == 0) {
- ret = changed_cb(left_path, right_path,
- &left_key,
- BTRFS_COMPARE_TREE_NEW,
- ctx);
- if (ret < 0)
- goto out;
- }
- advance_left = ADVANCE;
- continue;
- }
-
- if (left_level == 0 && right_level == 0) {
- cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
- if (cmp < 0) {
- ret = changed_cb(left_path, right_path,
- &left_key,
- BTRFS_COMPARE_TREE_NEW,
- ctx);
- if (ret < 0)
- goto out;
- advance_left = ADVANCE;
- } else if (cmp > 0) {
- ret = changed_cb(left_path, right_path,
- &right_key,
- BTRFS_COMPARE_TREE_DELETED,
- ctx);
- if (ret < 0)
- goto out;
- advance_right = ADVANCE;
- } else {
- enum btrfs_compare_tree_result result;
-
- WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
- ret = tree_compare_item(left_path, right_path,
- tmp_buf);
- if (ret)
- result = BTRFS_COMPARE_TREE_CHANGED;
- else
- result = BTRFS_COMPARE_TREE_SAME;
- ret = changed_cb(left_path, right_path,
- &left_key, result, ctx);
- if (ret < 0)
- goto out;
- advance_left = ADVANCE;
- advance_right = ADVANCE;
- }
- } else if (left_level == right_level) {
- cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
- if (cmp < 0) {
- advance_left = ADVANCE;
- } else if (cmp > 0) {
- advance_right = ADVANCE;
- } else {
- left_blockptr = btrfs_node_blockptr(
- left_path->nodes[left_level],
- left_path->slots[left_level]);
- right_blockptr = btrfs_node_blockptr(
- right_path->nodes[right_level],
- right_path->slots[right_level]);
- left_gen = btrfs_node_ptr_generation(
- left_path->nodes[left_level],
- left_path->slots[left_level]);
- right_gen = btrfs_node_ptr_generation(
- right_path->nodes[right_level],
- right_path->slots[right_level]);
- if (left_blockptr == right_blockptr &&
- left_gen == right_gen) {
- /*
- * As we're on a shared block, don't
- * allow to go deeper.
- */
- advance_left = ADVANCE_ONLY_NEXT;
- advance_right = ADVANCE_ONLY_NEXT;
- } else {
- advance_left = ADVANCE;
- advance_right = ADVANCE;
- }
- }
- } else if (left_level < right_level) {
- advance_right = ADVANCE;
- } else {
- advance_left = ADVANCE;
- }
- }
-
-out:
- btrfs_free_path(left_path);
- btrfs_free_path(right_path);
- kvfree(tmp_buf);
- 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
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 70a80db23ecc..1fd5931a9489 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2589,20 +2589,6 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
int slot);
-enum btrfs_compare_tree_result {
- BTRFS_COMPARE_TREE_NEW,
- BTRFS_COMPARE_TREE_DELETED,
- BTRFS_COMPARE_TREE_CHANGED,
- BTRFS_COMPARE_TREE_SAME,
-};
-typedef int (*btrfs_changed_cb_t)(struct btrfs_path *left_path,
- struct btrfs_path *right_path,
- struct btrfs_key *key,
- enum btrfs_compare_tree_result result,
- void *ctx);
-int btrfs_compare_trees(struct btrfs_root *left_root,
- struct btrfs_root *right_root,
- btrfs_changed_cb_t cb, void *ctx);
int btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index c3c0c064c25d..f856d6ca3771 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -260,6 +260,21 @@ struct name_cache_entry {
char name[];
};
+#define ADVANCE 1
+#define ADVANCE_ONLY_NEXT -1
+
+enum btrfs_compare_tree_result {
+ BTRFS_COMPARE_TREE_NEW,
+ BTRFS_COMPARE_TREE_DELETED,
+ BTRFS_COMPARE_TREE_CHANGED,
+ BTRFS_COMPARE_TREE_SAME,
+};
+typedef int (*btrfs_changed_cb_t)(struct btrfs_path *left_path,
+ struct btrfs_path *right_path,
+ struct btrfs_key *key,
+ enum btrfs_compare_tree_result result,
+ void *ctx);
+
__cold
static void inconsistent_snapshot_error(struct send_ctx *sctx,
enum btrfs_compare_tree_result result,
@@ -6514,6 +6529,365 @@ static int full_send_tree(struct send_ctx *sctx)
return ret;
}
+static int tree_move_down(struct btrfs_path *path, int *level)
+{
+ struct extent_buffer *eb;
+
+ BUG_ON(*level == 0);
+ eb = btrfs_read_node_slot(path->nodes[*level], path->slots[*level]);
+ if (IS_ERR(eb))
+ return PTR_ERR(eb);
+
+ path->nodes[*level - 1] = eb;
+ path->slots[*level - 1] = 0;
+ (*level)--;
+ return 0;
+}
+
+static int tree_move_next_or_upnext(struct btrfs_path *path,
+ int *level, int root_level)
+{
+ int ret = 0;
+ int nritems;
+ nritems = btrfs_header_nritems(path->nodes[*level]);
+
+ path->slots[*level]++;
+
+ while (path->slots[*level] >= nritems) {
+ if (*level == root_level)
+ return -1;
+
+ /* move upnext */
+ path->slots[*level] = 0;
+ free_extent_buffer(path->nodes[*level]);
+ path->nodes[*level] = NULL;
+ (*level)++;
+ path->slots[*level]++;
+
+ nritems = btrfs_header_nritems(path->nodes[*level]);
+ ret = 1;
+ }
+ return ret;
+}
+
+/*
+ * Returns 1 if it had to move up and next. 0 is returned if it moved only next
+ * or down.
+ */
+static int tree_advance(struct btrfs_path *path,
+ int *level, int root_level,
+ int allow_down,
+ struct btrfs_key *key)
+{
+ int ret;
+
+ if (*level == 0 || !allow_down) {
+ ret = tree_move_next_or_upnext(path, level, root_level);
+ } else {
+ ret = tree_move_down(path, level);
+ }
+ if (ret >= 0) {
+ if (*level == 0)
+ btrfs_item_key_to_cpu(path->nodes[*level], key,
+ path->slots[*level]);
+ else
+ btrfs_node_key_to_cpu(path->nodes[*level], key,
+ path->slots[*level]);
+ }
+ return ret;
+}
+
+static int tree_compare_item(struct btrfs_path *left_path,
+ struct btrfs_path *right_path,
+ char *tmp_buf)
+{
+ int cmp;
+ int len1, len2;
+ unsigned long off1, off2;
+
+ len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]);
+ len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]);
+ if (len1 != len2)
+ return 1;
+
+ off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
+ off2 = btrfs_item_ptr_offset(right_path->nodes[0],
+ right_path->slots[0]);
+
+ read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
+
+ cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
+ if (cmp)
+ return 1;
+ return 0;
+}
+
+/*
+ * This function compares two trees and calls the provided callback for
+ * every changed/new/deleted item it finds.
+ * If shared tree blocks are encountered, whole subtrees are skipped, making
+ * the compare pretty fast on snapshotted subvolumes.
+ *
+ * This currently works on commit roots only. As commit roots are read only,
+ * we don't do any locking. The commit roots are protected with transactions.
+ * Transactions are ended and rejoined when a commit is tried in between.
+ *
+ * This function checks for modifications done to the trees while comparing.
+ * If it detects a change, it aborts immediately.
+ */
+static int btrfs_compare_trees(struct btrfs_root *left_root,
+ struct btrfs_root *right_root,
+ btrfs_changed_cb_t changed_cb, void *ctx)
+{
+ struct btrfs_fs_info *fs_info = left_root->fs_info;
+ int ret;
+ int cmp;
+ struct btrfs_path *left_path = NULL;
+ struct btrfs_path *right_path = NULL;
+ struct btrfs_key left_key;
+ struct btrfs_key right_key;
+ char *tmp_buf = NULL;
+ int left_root_level;
+ int right_root_level;
+ int left_level;
+ int right_level;
+ int left_end_reached;
+ int right_end_reached;
+ int advance_left;
+ int advance_right;
+ u64 left_blockptr;
+ u64 right_blockptr;
+ u64 left_gen;
+ u64 right_gen;
+
+ left_path = btrfs_alloc_path();
+ if (!left_path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ right_path = btrfs_alloc_path();
+ if (!right_path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ tmp_buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
+ if (!tmp_buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ left_path->search_commit_root = 1;
+ left_path->skip_locking = 1;
+ right_path->search_commit_root = 1;
+ right_path->skip_locking = 1;
+
+ /*
+ * Strategy: Go to the first items of both trees. Then do
+ *
+ * If both trees are at level 0
+ * Compare keys of current items
+ * If left < right treat left item as new, advance left tree
+ * and repeat
+ * If left > right treat right item as deleted, advance right tree
+ * and repeat
+ * If left == right do deep compare of items, treat as changed if
+ * needed, advance both trees and repeat
+ * If both trees are at the same level but not at level 0
+ * Compare keys of current nodes/leafs
+ * If left < right advance left tree and repeat
+ * If left > right advance right tree and repeat
+ * If left == right compare blockptrs of the next nodes/leafs
+ * If they match advance both trees but stay at the same level
+ * and repeat
+ * If they don't match advance both trees while allowing to go
+ * deeper and repeat
+ * If tree levels are different
+ * Advance the tree that needs it and repeat
+ *
+ * Advancing a tree means:
+ * If we are at level 0, try to go to the next slot. If that's not
+ * possible, go one level up and repeat. Stop when we found a level
+ * where we could go to the next slot. We may at this point be on a
+ * node or a leaf.
+ *
+ * If we are not at level 0 and not on shared tree blocks, go one
+ * level deeper.
+ *
+ * If we are not at level 0 and on shared tree blocks, go one slot to
+ * the right if possible or go up and right.
+ */
+
+ down_read(&fs_info->commit_root_sem);
+ left_level = btrfs_header_level(left_root->commit_root);
+ left_root_level = left_level;
+ left_path->nodes[left_level] =
+ btrfs_clone_extent_buffer(left_root->commit_root);
+ if (!left_path->nodes[left_level]) {
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ right_level = btrfs_header_level(right_root->commit_root);
+ right_root_level = right_level;
+ right_path->nodes[right_level] =
+ btrfs_clone_extent_buffer(right_root->commit_root);
+ if (!right_path->nodes[right_level]) {
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOMEM;
+ goto out;
+ }
+ up_read(&fs_info->commit_root_sem);
+
+ if (left_level == 0)
+ btrfs_item_key_to_cpu(left_path->nodes[left_level],
+ &left_key, left_path->slots[left_level]);
+ else
+ btrfs_node_key_to_cpu(left_path->nodes[left_level],
+ &left_key, left_path->slots[left_level]);
+ if (right_level == 0)
+ btrfs_item_key_to_cpu(right_path->nodes[right_level],
+ &right_key, right_path->slots[right_level]);
+ else
+ btrfs_node_key_to_cpu(right_path->nodes[right_level],
+ &right_key, right_path->slots[right_level]);
+
+ left_end_reached = right_end_reached = 0;
+ advance_left = advance_right = 0;
+
+ while (1) {
+ if (advance_left && !left_end_reached) {
+ ret = tree_advance(left_path, &left_level,
+ left_root_level,
+ advance_left != ADVANCE_ONLY_NEXT,
+ &left_key);
+ if (ret == -1)
+ left_end_reached = ADVANCE;
+ else if (ret < 0)
+ goto out;
+ advance_left = 0;
+ }
+ if (advance_right && !right_end_reached) {
+ ret = tree_advance(right_path, &right_level,
+ right_root_level,
+ advance_right != ADVANCE_ONLY_NEXT,
+ &right_key);
+ if (ret == -1)
+ right_end_reached = ADVANCE;
+ else if (ret < 0)
+ goto out;
+ advance_right = 0;
+ }
+
+ if (left_end_reached && right_end_reached) {
+ ret = 0;
+ goto out;
+ } else if (left_end_reached) {
+ if (right_level == 0) {
+ ret = changed_cb(left_path, right_path,
+ &right_key,
+ BTRFS_COMPARE_TREE_DELETED,
+ ctx);
+ if (ret < 0)
+ goto out;
+ }
+ advance_right = ADVANCE;
+ continue;
+ } else if (right_end_reached) {
+ if (left_level == 0) {
+ ret = changed_cb(left_path, right_path,
+ &left_key,
+ BTRFS_COMPARE_TREE_NEW,
+ ctx);
+ if (ret < 0)
+ goto out;
+ }
+ advance_left = ADVANCE;
+ continue;
+ }
+
+ if (left_level == 0 && right_level == 0) {
+ cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
+ if (cmp < 0) {
+ ret = changed_cb(left_path, right_path,
+ &left_key,
+ BTRFS_COMPARE_TREE_NEW,
+ ctx);
+ if (ret < 0)
+ goto out;
+ advance_left = ADVANCE;
+ } else if (cmp > 0) {
+ ret = changed_cb(left_path, right_path,
+ &right_key,
+ BTRFS_COMPARE_TREE_DELETED,
+ ctx);
+ if (ret < 0)
+ goto out;
+ advance_right = ADVANCE;
+ } else {
+ enum btrfs_compare_tree_result result;
+
+ WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
+ ret = tree_compare_item(left_path, right_path,
+ tmp_buf);
+ if (ret)
+ result = BTRFS_COMPARE_TREE_CHANGED;
+ else
+ result = BTRFS_COMPARE_TREE_SAME;
+ ret = changed_cb(left_path, right_path,
+ &left_key, result, ctx);
+ if (ret < 0)
+ goto out;
+ advance_left = ADVANCE;
+ advance_right = ADVANCE;
+ }
+ } else if (left_level == right_level) {
+ cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
+ if (cmp < 0) {
+ advance_left = ADVANCE;
+ } else if (cmp > 0) {
+ advance_right = ADVANCE;
+ } else {
+ left_blockptr = btrfs_node_blockptr(
+ left_path->nodes[left_level],
+ left_path->slots[left_level]);
+ right_blockptr = btrfs_node_blockptr(
+ right_path->nodes[right_level],
+ right_path->slots[right_level]);
+ left_gen = btrfs_node_ptr_generation(
+ left_path->nodes[left_level],
+ left_path->slots[left_level]);
+ right_gen = btrfs_node_ptr_generation(
+ right_path->nodes[right_level],
+ right_path->slots[right_level]);
+ if (left_blockptr == right_blockptr &&
+ left_gen == right_gen) {
+ /*
+ * As we're on a shared block, don't
+ * allow to go deeper.
+ */
+ advance_left = ADVANCE_ONLY_NEXT;
+ advance_right = ADVANCE_ONLY_NEXT;
+ } else {
+ advance_left = ADVANCE;
+ advance_right = ADVANCE;
+ }
+ }
+ } else if (left_level < right_level) {
+ advance_right = ADVANCE;
+ } else {
+ advance_left = ADVANCE;
+ }
+ }
+
+out:
+ btrfs_free_path(left_path);
+ btrfs_free_path(right_path);
+ kvfree(tmp_buf);
+ return ret;
+}
+
static int send_subvol(struct send_ctx *sctx)
{
int ret;
--
2.22.0
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