On Wed, Jul 18, 2012 at 7:45 PM, Alex Lyakas <alex.bolshoy.bt...@gmail.com> wrote: > Hi Alexander, > I am testing different scenarios in order to better understand the > non-trivial magic of > get_cur_path()/will_overwrite_ref()/did_overwrite_ref()/did_overwrite_first_ref(). > I hit the following issue, when testing full-send: > > This is my source subvolume (inode numbers are written): > tree -A --inodes --noreport /mnt/src/tmp/ > /mnt/src/tmp/ > └── [ 270] dir2 > └── [ 268] file1_nod > > As you see, the ino(file1_nod) < ino(dir2). It is very easy to > achieve: first create the file, then the dir, and then move the file > to dir. > > During send the following happens (I augmented the send code with many > prints): > > file1_nod is sent first. Since its a new inode, it is sent as an > orphan. When recording its reference, __record_new_ref() calls > get_cur_path() for its parent (270). Then __get_cur_name_and_parent() > is called on 270, which calls is_inode_existent(), which calls > get_cur_inode_state(), and the state of the parent is "will_create". > So __get_cur_name_and_parent() creates an orphan name for it, and > finally the new reference for 268 is recorded as: > o270-136-0/file1_nod: > > [changed_cb:4102] key(256 INODE_ITEM 0) : NEW > [changed_cb:4102] key(256 INODE_REF 256) : NEW > [changed_cb:4102] key(268 INODE_ITEM 0) : NEW > [send_create_inode:2407] NEW ino(268,135) type=0100000, path=[o268-135-0] > [changed_cb:4102] key(268 INODE_REF 270) : NEW > [get_cur_inode_state:1475] (270,136): L(EX,136) > R(NE,18446744072099047770) sp=268 ==> will_create > [is_inode_existent:1498] (270,136): NOT existent > [__get_cur_name_and_parent:1918] ino(270,136) not existent => unique > name [o270-136-0] > [get_cur_path:2051] ino(0,0) cur_path=[o270-136-0] > [__record_new_ref:2911] record new ref [o270-136-0/file1_nod] > > Then process_recorded_refs() sees that 268 is still orphan, so it > sends "rename" to its valid place, but the problem is that its parent > dir was not sent yet (and its parent dir is also an orphan): > [process_recorded_refs:2601] ino(268,135): start with refs > [28118.347602] [process_recorded_refs:2651] ino(268,135): new=1, > did_overwrite_first_ref=0, is_orphan=1, valid_path=[o268-135-0] > [28118.347605] [process_recorded_refs:2701] ino(268,135): is orphan, > move it: [o268-135-0]=>[o270-136-0/file1_nod] > [28118.347610] [process_recorded_refs:2837] checking dir(270,136) > [28118.347612] [process_recorded_refs:2869] ino(268,135) done with refs > > Now the parent dir is processed: > [changed_cb:4102] key(270 INODE_ITEM 0) : NEW > [send_create_inode:2407] NEW ino(270,136) type=040000, path=[o270-136-0] > [changed_cb:4102] key(270 INODE_REF 256) : NEW > [get_cur_path:2051] ino(256,133) cur_path=[] > [__record_new_ref:2911] record new ref [dir2] > [process_recorded_refs:2601] ino(270,136): start with refs > [process_recorded_refs:2651] ino(270,136): new=1, > did_overwrite_first_ref=0, is_orphan=1, valid_path=[o270-136-0] > [process_recorded_refs:2701] ino(270,136): is orphan, move it: > [o270-136-0]=>[dir2] > [process_recorded_refs:2837] checking dir(256,133) > [get_cur_inode_state:1475] (256,133): L(EX,133) > R(NE,18446612135413283512) sp=270 ==> did_create > [process_recorded_refs:2869] ino(270,136) done with refs > > Nothing special here, the parent is first sent as an orphan, and then > renamed to its valid name, but it's too late. > > During receive: > ERROR: rename o268-135-0 -> o270-136-0/file1_nod failed. No such file > or directory > > I am not yet sure where is the proper place to fix this, I just wanted > to report it first. Basically, I think that when sending any kind of > A_PATH, it is needed to ensure that path components exist, either as > orphan or real path (by sending them out-of-order if needed?). But I > am not yet sure where is the core place that should ensure this. > > Thanks, > Alex.
I have pushed a fix for this case. Basically, the solution is to postpone the processing of refs in not created dirs until the dir is created. Big thanks for investigating this one. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
