Btrfs: part 2, fix incremental send's decision to delay a dir move/rename
For an incremental send, fix the process of determining whether the directory inode we're currently processing needs to have its move/rename operation delayed. We were ignoring the fact that if the inode's new immediate ancestor has a higher inode number than ours but wasn't renamed/moved, we might still need to delay our move/rename, because some other ancestor directory higher in the hierarchy might have an inode number higher than ours *and* was renamed/moved too - in this case we have to wait for rename/move of that ancestor to happen before our current directory's rename/move operation. Simple steps to reproduce this issue: $ mkfs.btrfs -f /dev/sdd $ mount /dev/sdd /mnt $ mkdir -p /mnt/a/x1/x2 $ mkdir /mnt/a/Z $ mkdir -p /mnt/a/x1/x2/x3/x4/x5 $ btrfs subvolume snapshot -r /mnt /mnt/snap1 $ btrfs send /mnt/snap1 -f /tmp/base.send $ mv /mnt/a/x1/x2/x3 /mnt/a/Z/X33 $ mv /mnt/a/x1/x2 /mnt/a/Z/X33/x4/x5/X22 $ btrfs subvolume snapshot -r /mnt /mnt/snap2 $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send The incremental send caused the kernel code to enter an infinite loop when building the path string for directory Z after its references are processed. A more complex scenario: $ mkfs.btrfs -f /dev/sdd $ mount /dev/sdd /mnt $ mkdir -p /mnt/a/b/c/d $ mkdir /mnt/a/b/c/d/e $ mkdir /mnt/a/b/c/d/f $ mv /mnt/a/b/c/d/e /mnt/a/b/c/d/f/E2 $ mkdir /mmt/a/b/c/g $ mv /mnt/a/b/c/d /mnt/a/b/D2 $ btrfs subvolume snapshot -r /mnt /mnt/snap1 $ btrfs send /mnt/snap1 -f /tmp/base.send $ mkdir /mnt/a/o $ mv /mnt/a/b/c/g /mnt/a/b/D2/f/G2 $ mv /mnt/a/b/D2 /mnt/a/b/dd $ mv /mnt/a/b/c /mnt/a/C2 $ mv /mnt/a/b/dd/f /mnt/a/o/FF $ mv /mnt/a/b /mnt/a/o/FF/E2/BB $ btrfs subvolume snapshot -r /mnt /mnt/snap2 $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send A test case for xfstests follows. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Chris Mason <clm@fb.com>
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@ -2916,7 +2916,10 @@ static void free_waiting_dir_move(struct send_ctx *sctx,
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kfree(dm);
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}
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static int add_pending_dir_move(struct send_ctx *sctx, u64 parent_ino)
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static int add_pending_dir_move(struct send_ctx *sctx,
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u64 ino,
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u64 ino_gen,
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u64 parent_ino)
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{
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struct rb_node **p = &sctx->pending_dir_moves.rb_node;
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struct rb_node *parent = NULL;
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@ -2929,8 +2932,8 @@ static int add_pending_dir_move(struct send_ctx *sctx, u64 parent_ino)
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if (!pm)
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return -ENOMEM;
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pm->parent_ino = parent_ino;
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pm->ino = sctx->cur_ino;
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pm->gen = sctx->cur_inode_gen;
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pm->ino = ino;
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pm->gen = ino_gen;
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INIT_LIST_HEAD(&pm->list);
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INIT_LIST_HEAD(&pm->update_refs);
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RB_CLEAR_NODE(&pm->node);
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@ -3183,6 +3186,8 @@ static int wait_for_parent_move(struct send_ctx *sctx,
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struct fs_path *path_before = NULL;
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struct fs_path *path_after = NULL;
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int len1, len2;
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int register_upper_dirs;
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u64 gen;
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if (is_waiting_for_move(sctx, ino))
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return 1;
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@ -3220,7 +3225,7 @@ static int wait_for_parent_move(struct send_ctx *sctx,
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}
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ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
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NULL, path_after);
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&gen, path_after);
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if (ret == -ENOENT) {
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ret = 0;
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goto out;
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@ -3237,6 +3242,60 @@ static int wait_for_parent_move(struct send_ctx *sctx,
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}
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ret = 0;
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/*
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* Ok, our new most direct ancestor has a higher inode number but
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* wasn't moved/renamed. So maybe some of the new ancestors higher in
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* the hierarchy have an higher inode number too *and* were renamed
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* or moved - in this case we need to wait for the ancestor's rename
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* or move operation before we can do the move/rename for the current
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* inode.
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*/
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register_upper_dirs = 0;
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ino = parent_ino_after;
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again:
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while ((ret == 0 || register_upper_dirs) && ino > sctx->cur_ino) {
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u64 parent_gen;
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fs_path_reset(path_before);
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fs_path_reset(path_after);
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ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
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&parent_gen, path_after);
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if (ret < 0)
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goto out;
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ret = get_first_ref(sctx->parent_root, ino, &parent_ino_before,
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NULL, path_before);
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if (ret == -ENOENT) {
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ret = 0;
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break;
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} else if (ret < 0) {
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goto out;
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}
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len1 = fs_path_len(path_before);
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len2 = fs_path_len(path_after);
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if (parent_ino_before != parent_ino_after || len1 != len2 ||
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memcmp(path_before->start, path_after->start, len1)) {
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ret = 1;
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if (register_upper_dirs) {
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break;
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} else {
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register_upper_dirs = 1;
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ino = parent_ref->dir;
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gen = parent_ref->dir_gen;
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goto again;
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}
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} else if (register_upper_dirs) {
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ret = add_pending_dir_move(sctx, ino, gen,
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parent_ino_after);
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if (ret < 0 && ret != -EEXIST)
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goto out;
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}
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ino = parent_ino_after;
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gen = parent_gen;
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}
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out:
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fs_path_free(path_before);
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fs_path_free(path_after);
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@ -3402,7 +3461,9 @@ verbose_printk("btrfs: process_recorded_refs %llu\n", sctx->cur_ino);
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goto out;
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if (ret) {
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ret = add_pending_dir_move(sctx,
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cur->dir);
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sctx->cur_ino,
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sctx->cur_inode_gen,
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cur->dir);
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*pending_move = 1;
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} else {
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ret = send_rename(sctx, valid_path,
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