Re: [PATCH] refs: work around network caching on Windows

> Network shares sometimes use aggressive caching, in which case a
> just-created directory might not be immediately visible to Git.
>
> One symptom of this scenario is the following error:
>
>         $ git tag -a -m "automatic tag creation"  test_dir/test_tag
>         fatal: cannot lock ref 'refs/tags/test_dir/test_tag': unable to resolve reference 'refs/tags/test_dir/test_tag': Not a directory
>
> Note: This does not necessarily happen in all Windows setups. One setup
> where it _did_ happen is a Windows Server 2019 VM, and as hinted in
>
>         http://woshub.com/slow-network-shared-folder-refresh-windows-server/
>
> the following commands worked around it:
>
>         Set-SmbClientConfiguration -DirectoryCacheLifetime 0
>         Set-SmbClientConfiguration -FileInfoCacheLifetime 0
>         Set-SmbClientConfiguration -FileNotFoundCacheLifetime 0
>
> This would impact performance negatively, though, as it essentially
> turns off all caching, therefore we do not want to require users to do
> that just to be able to use Git on Windows.
>
> The underlying culprit is that `GetFileAttributesExW()` that is called from
> `mingw_lstat()` can raise an error `ERROR_PATH_NOT_FOUND`, which is
> translated to `ENOTDIR`, as opposed to `ENOENT` as expected on Linux.
>
> Therefore, when trying to read a ref, let's allow `ENOTDIR` in addition
> to `ENOENT` to indicate that said ref is missing.
>
> This fixes https://github.com/git-for-windows/git/issues/3727
>
> Signed-off-by: Pierre Garnier <pgarnier@mega.com>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> diff --git a/refs/files-backend.c b/refs/files-backend.c
> @@ -381,7 +381,7 @@ stat_ref:
> -               if (myerr != ENOENT || skip_packed_refs)
> +               if ((myerr != ENOENT && myerr != ENOTDIR) || skip_packed_refs)
> diff --git a/refs/packed-backend.c b/refs/packed-backend.c
> @@ -480,7 +480,7 @@ static int load_contents(struct snapshot *snapshot)
> -               if (errno == ENOENT) {
> +               if (errno == ENOENT || errno == ENOTDIR) {