rsync - Jan 2016 - [Bug 11668] New: incorrect/inconsistent behavior when --backup-dir is on a full filesystem

https://bugzilla.samba.org/show_bug.cgi?id=11668

            Bug ID: 11668
           Summary: incorrect/inconsistent behavior when --backup-dir is
                    on a full filesystem
           Product: rsync
           Version: 3.1.2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P5
         Component: core
          Assignee: wayned at samba.org
          Reporter: abezella at archive.org
        QA Contact: rsync-qa at samba.org

hello - we are having some issues w/the exit value of `rsync --backup` when
--backup-dir is on a full filesystem.

for instance:
* rsync  version 3.1.2  protocol version 31
* the filesystem mounted on /2 is 100% full, /1 has plenty of space

when the destination files exist but a delta needs to be transmitted,
running:
> rsync -av --delete -b --backup-dir=/2/tmp
rsync://instance0.us.archive.org/items_11/McGillLibrary-129621-5035 /1/2.1/.
results in:
> receiving incremental file list
> McGillLibrary-129621-5035/129621_scandata.xml
> rsync: backup mkdir /2/tmp/McGillLibrary-129621-5035 failed: No space left
on device (28)
> 
> sent 164 bytes  received 1,333 bytes  2,994.00 bytes/sec
> total size is 26,763,596  speedup is 17,878.15
and an exit status of 0 despite the error.  the file-to-be-modified remains
unchanged, and the rsync tmpfile that is transferred over is left in place.

subsequent runs of the command also fail, but with an exit value of 23 (i'm
guessing because the make_backup reports failing as well as the "backup
mkdir"?):
> receiving incremental file list
> rsync: backup mkdir /2/tmp/McGillLibrary-129621-5035 failed: No space left
on device (28)
> rsync: delete_file:
make_backup(McGillLibrary-129621-5035/.129621_scandata.xml.nKW4Sg) failed:
Success (0)
> McGillLibrary-129621-5035/129621_scandata.xml
> rsync: backup mkdir /2/tmp/McGillLibrary-129621-5035 failed: No space left
on device (28)
> 
> sent 164 bytes  received 1,333 bytes  2,994.00 bytes/sec
> total size is 26,763,596  speedup is 17,878.15
> rsync error: some files/attrs were not transferred (see previous errors)
(code 23) at main.c(1650) [generator=3.1.2]
i _believe_ that this behavior started in 3.1.0 (best recollection is that
3.0.9 did not suffer from this, although
https://lists.samba.org/archive/rsync/2013-July/028488.html looks like it may
be related).

thank you in advance for any help you can provide, and thanks for rsync! 
please let me know if there is additional information that may be useful or
further tests that can be run.

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https://bugzilla.samba.org/show_bug.cgi?id=11668

--- Comment #1 from Jim Nelson <jnelson at archive.org> ---
I've investigated this problem and coded a patch, which I will attach after
posting this comment.  I also coded a test case for the test suite.

Using the test case and git bisect, I determined the problem was introduced in
this commit:

commit 21cddef2b460098f5289b9cdbd592bf8f0f9e759
Author: Wayne Davison <wayned at samba.org>
Date:   Sat Jan 3 12:00:02 2009 -0800

    Improved the backup code:
    - Backups do not interfere with an atomic update (when possible).
    - Backing up a file will remove a directory that is in the way
      and visa versa.
    - Unify the backup-dir and non-backup-dir code in backup.c.
    - Improved the backup tests a little bit.

It appears this 2009 patch was excluded from v3.0.9 but included in v3.1.0 and
onward, which explains why Andrew didn't see it until the later release.

The test case requires root (to mount a small file-based file system and fill
it to capacity).  It uses trap to unmount the fs in case of error and not leave
the system in a poor state.

My proposed patch is straightforward: if unable to make the backup, call
exit_cleanup(RERR_FILEIO).

I'd very much like to see this bug fixed, so please let me know if
there's
anything I can do to improve either patch for inclusion.

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--- Comment #2 from Jim Nelson <jnelson at archive.org> ---
Created attachment 11960
  --> https://bugzilla.samba.org/attachment.cgi?id=11960&action=edit
Test case for test suite

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--- Comment #3 from Jim Nelson <jnelson at archive.org> ---
Created attachment 11961
  --> https://bugzilla.samba.org/attachment.cgi?id=11961&action=edit
Proposed patch

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Wayne Davison <wayned at samba.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #4 from Wayne Davison <wayned at samba.org> ---
Thanks for the patch and the test case. I haven't included the test in the
suite because it's not usually run as root.  Fixed in git:
b973bffa949a2407768e4ec8fb501b3fbe932f91.

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