This reverts commit 5f806c3ae2ff6263a10a6901f97abb74dac03d36.
Btrfs: incremental send, avoid ancestor rename to descendant
There's one more case where we can't issue a rename operation for a directory
as soon as we process it. We move a directory from ancestor to descendant.
|---- a
|---- b
|---- c
|---- d
"Move a directory from ancestor to descendant" means moving dir. a into dir. c
This case will happen after applying "[PATCH] Btrfs: incremental send,
don't delay directory renames unnecessarily".
Because, that patch changes behavior of wait_for_parent_move function.
Parent snapshot:
|---- @tmp/ (ino 257)
|---- pre/ (ino 259)
|---- wait_dir (ino 260)
|---- finish_dir2/ (ino 261)
|---- ance/ (ino 263)
|---- finish_dir1/ (ino 258)
|---- desc/ (ino 262)
|---- other_dir/ (ino 264)
Send snapshot:
|---- @tmp/ (ino 257)
|---- other_dir/ (ino 264)
|---- wait_dir/ (ino 260)
|---- finish_dir2/ (ino 261)
|---- desc/ (ino 262)
|---- ance/ (ino 263)
|---- finish_dir1/ (ino 258)
|---- pre/ (ino 259)
1. 259 can not move under 258 because 263 needs to move to 263 first.
So 259 is waiting on ance(263).
2. 260 must move to @tmp/other_dir, so it is waiting on other_dir(264).
3. 262 is able to rename as pre/wait_dir/finish_dir2(261)/desc since
wait_dir(260) is waiting and 262 is not the ancestor of wait_dir(260).
4.263 is able to rename as pre/wait_dir/finish_dir2(261)/ance since
wait_dir(260) is waiting and 263 is not the ancestor of wait_dir(260).
5. After wait_dir(263) is finished, all pending dirs. start to run.
/pre(259) in apply_dir_move() renames /pre as
pre/wait_dir/finish_dir2/desc/ance/finish_dir1/pre
At the same time, receiving side will encounter error.
If anyone calls get_cur_path() to any element in
pre/wait_dir/finish_dir2/desc/ance/finish_dir1/pre like wait_dir(260)
,
there will cause path building loop like this : 260 -> 259 -> 258 ->
263 -> 262 -> 261 -> 260
So fix the problem by check path_loop for this case.
Signed-off-by: Robbie Ko <[email protected]>
---
fs/btrfs/send.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 59 insertions(+)
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 1c1f161..257753b 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -3080,6 +3080,48 @@ static struct pending_dir_move
*get_pending_dir_moves(struct send_ctx *sctx,
return NULL;
}
+static int path_loop(struct send_ctx *sctx, struct fs_path *name,
+ u64 ino, u64 gen, u64 *ancestor_ino)
+{
+ int ret = 0;
+ u64 parent_inode = 0;
+ u64 parent_gen = 0;
+ u64 start_ino = ino;
+
+ *ancestor_ino = 0;
+ while (ino != BTRFS_FIRST_FREE_OBJECTID) {
+ fs_path_reset(name);
+
+ if (is_waiting_for_rm(sctx, ino))
+ break;
+ if (is_waiting_for_move(sctx, ino)) {
+ if (*ancestor_ino == 0)
+ *ancestor_ino = ino;
+ ret = get_first_ref(sctx->parent_root, ino,
+ &parent_inode, &parent_gen, name);
+ } else {
+ ret = __get_cur_name_and_parent(sctx, ino, gen,
+ &parent_inode,
+ &parent_gen, name);
+ if (ret > 0) {
+ ret = 0;
+ break;
+ }
+ }
+ if (ret < 0)
+ break;
+ if (parent_inode == start_ino) {
+ ret = 1;
+ if (*ancestor_ino == 0)
+ *ancestor_ino = ino;
+ break;
+ }
+ ino = parent_inode;
+ gen = parent_gen;
+ }
+ return ret;
+}
+
static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
{
struct fs_path *from_path = NULL;
@@ -3091,6 +3133,7 @@ static int apply_dir_move(struct send_ctx *sctx, struct
pending_dir_move *pm)
struct waiting_dir_move *dm = NULL;
u64 rmdir_ino = 0;
int ret;
+ u64 ancestor = 0;
name = fs_path_alloc();
from_path = fs_path_alloc();
@@ -3122,6 +3165,22 @@ static int apply_dir_move(struct send_ctx *sctx, struct
pending_dir_move *pm)
goto out;
sctx->send_progress = sctx->cur_ino + 1;
+ ret = path_loop(sctx, name, pm->ino, pm->gen, &ancestor);
+ if (ret) {
+ LIST_HEAD(deleted_refs);
+ ASSERT(ancestor > BTRFS_FIRST_FREE_OBJECTID);
+ ret = add_pending_dir_move(sctx, pm->ino, pm->gen, ancestor,
+ &pm->update_refs, &deleted_refs,
+ pm->is_orphan);
+ if (ret < 0)
+ goto out;
+ if (rmdir_ino) {
+ dm = get_waiting_dir_move(sctx, pm->ino);
+ ASSERT(dm);
+ dm->rmdir_ino = rmdir_ino;
+ }
+ goto out;
+ }
fs_path_reset(name);
to_path = name;
name = NULL;
--
1.9.1
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