On Wed, Apr 12, 2017 at 10:37 PM, Kevin Willford <kewillf@xxxxxxxxxxxxx> wrote: > >> -----Original Message----- >> From: git-owner@xxxxxxxxxxxxxxx [mailto:git-owner@xxxxxxxxxxxxxxx] On >> Behalf Of Duy Nguyen >> Sent: Wednesday, April 12, 2017 7:21 AM >> To: Kevin Willford <kewillf@xxxxxxxxxxxxx> >> Cc: Kevin Willford <kcwillford@xxxxxxxxx>; git@xxxxxxxxxxxxxxx; >> gitster@xxxxxxxxx; peff@xxxxxxxx >> Subject: Re: [PATCH 3/3] reset.c: update files when using sparse to avoid >> data loss. >> >> On Wed, Apr 12, 2017 at 5:30 AM, Kevin Willford <kewillf@xxxxxxxxxxxxx> >> wrote: >> > The loss of the skip-worktree bits is part of the problem if you are >> > talking about modified files. The other issue that I was having is >> > when running a reset and there were files added in the commit that is >> > being reset, there will not be an entry in the index and not a file on >> > disk so the data for that file is completely lost at that point. >> > "status" also doesn't include anything about this loss of data. On >> > modified files status will at least have the file as deleted since >> > there is still an index entry but again the previous version of the file and it's >> data is lost. >> >> Well, we could have "deleted" index entries, those marked with >> CE_REMOVE. They are never written down to file though, so 'status' >> won't benefit from that. Hopefully we can restore the file before the index >> file is written down and we really lose skip-worktree bits? > > Because this is a reset --mixed it will never run through unpack_trees and > The entries are never marked with CE_REMOVE. I know. But in my view, it should. All updates from a tree object to the index should happen through unpack_trees(). >> > To me this is totally unexpected behavior, for example if I am on a >> > commit where there are only files that where added and run a reset >> > HEAD~1 and then a status, it will show a clean working directory. >> > Regardless of skip-worktree bits the user needs to have the data in >> > the working directory after the reset or data is lost which is always bad. >> >> I agree we no longer have a place to save the skip-worktree bit, we have to >> restore the state back as if skip-worktree bit does not exist. >> It would be good if we could keep the logic in unpack_trees() though. >> For example, if the file is present on disk even if skip-worktree bit is on, >> unpack_trees() would abort instead of silently overwriting it. >> This is a difference between skip-worktree and assume-unchanged bits. >> If you do explicit checkout_entry() you might have to add more checks to >> keep behavior consistent. >> -- >> Duy > > Because this is a reset --mixed it will follow the code path calling read_from_tree > and ends up calling update_index_from_diff in the format_callback of the diff, > so unpack_trees() is never called in the --mixed case. This code change also only applies > when the file does not exist and the skip-worktree bit is on and the updated > index entry either will be missing (covers the added scenario) or was not missing > before (covers the modified scenario). If there is a better way to get the previous > index entry to disk than what I am doing, I am happy to implement it correctly. I think it's ok to just look at the diff (from update_index_from_diff) and restore the on-disk version for now. I'd like to make --mixed use unpack_trees() too but I haven't studied this code long enough to see why it went with "diff" instead of "read-tree" (which translates directly to unpack_trees). Maybe there is some subtle reason for that. Though it looks like it was more convenient to do "diff" in the git-reset.sh version, and that got translated literally to C when the command was rewritten. -- Duy