Base on [PATCH] Btrfs: incremental send, don't delay directory renames
unnecessarily
There's one 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,
if not wait_parent_move or wait_for_dest_dir_move so that happen path loop.
Example:
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)
Here we can not rename 263 from ance to
ance/finish_dir1/pre/wait_dir/finish_dir2/desc/ance
without the rename of inode 260, so that happen path loop.
So fix this by delaying directory renames for this case.
Signed-off-by: Robbie Ko <[email protected]>
---
fs/btrfs/send.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 95 insertions(+)
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index fbfbb8b..596b9dc 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -3078,6 +3078,56 @@ 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) {
+ struct waiting_dir_move *wdm;
+ fs_path_reset(name);
+
+ if (is_waiting_for_rm(sctx, ino))
+ break;
+
+ wdm = get_waiting_dir_move(sctx, ino);
+ if (wdm) {
+ if (*ancestor_ino == 0)
+ *ancestor_ino = ino;
+ if (wdm->orphanized) {
+ ret = gen_unique_name(sctx, ino, gen, name);
+ break;
+ } else {
+ 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;
@@ -3089,6 +3139,7 @@ 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;
bool is_orphan;
name = fs_path_alloc();
@@ -3122,6 +3173,22 @@ 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,
+
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;
@@ -3693,6 +3760,34 @@ verbose_printk("btrfs: process_recorded_refs %llu\n",
sctx->cur_ino);
}
/*
+ * if cur_ino is cur ancestor, can't move now,
+ * find descendant who is waiting, waiting it.
+ */
+ if (can_rename && (strncmp(valid_path->start,
cur->full_path->start, fs_path_len(valid_path)) == 0) &&
+
fs_path_len(cur->full_path) > fs_path_len(valid_path) &&
cur->full_path->start[fs_path_len(valid_path)] == '/') {
+ struct fs_path *name = NULL;
+ u64 ancestor;
+ u64 old_send_progress = sctx->send_progress;
+
+ name = fs_path_alloc();
+ sctx->send_progress = sctx->cur_ino + 1;
+ ret = path_loop(sctx, name, sctx->cur_ino,
sctx->cur_inode_gen, &ancestor);
+ if (ret) {
+ ret = add_pending_dir_move(sctx, sctx->cur_ino,
sctx->cur_inode_gen,
+ ancestor,
&sctx->new_refs, &sctx->deleted_refs, is_orphan);
+ if (ret < 0) {
+ sctx->send_progress = old_send_progress;
+ fs_path_free(name);
+ goto out;
+ }
+ can_rename = false;
+ *pending_move = 1;
+ }
+ sctx->send_progress = old_send_progress;
+ fs_path_free(name);
+ }
+
+ /*
* link/move the ref to the new place. If we have an orphan
* inode, move it and update valid_path. If not, link or move
* it depending on the inode mode.
--
1.9.1
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