[rdiff-backup-users] failing link(2) results in unhandled exception

[dean gaudet]

i had rdiff-backup 0.11.0 running smoothly for over a year and recently
started having problems with it failing to complete a backup.  figuring i
was long overdue for an upgrade i moved to deb unstable recent which is
0.13.3.jgoerzen-3 ... i'm still having problems with the backup failing to
complete.

here's the traceback i got this afternoon:

Traceback (most recent call last):
  File "/usr/bin/rdiff-backup", line 23, in ?
    rdiff_backup.Main.Main(sys.argv[1:])
  File "/usr/lib/python2.3/site-packages/rdiff_backup/Main.py", line 248, in 
Main
    take_action(rps)
  File "/usr/lib/python2.3/site-packages/rdiff_backup/Main.py", line 219, in 
take_action
    elif action == "backup": Backup(rps[0], rps[1])
  File "/usr/lib/python2.3/site-packages/rdiff_backup/Main.py", line 269, in 
Backup
    backup.Mirror(rpin, rpout)
  File "/usr/lib/python2.3/site-packages/rdiff_backup/backup.py", line 38, in 
Mirror
    DestS.patch(dest_rpath, source_diffiter)
  File "/usr/lib/python2.3/site-packages/rdiff_backup/backup.py", line 215, in 
patch
    ITR(diff.index, diff)
  File "/usr/lib/python2.3/site-packages/rdiff_backup/rorpiter.py", line 279, 
in __call__
    last_branch.fast_process(*args)
  File "/usr/lib/python2.3/site-packages/rdiff_backup/backup.py", line 473, in 
fast_process
    if self.patch_to_temp(rp, diff_rorp, tf):
  File "/usr/lib/python2.3/site-packages/rdiff_backup/backup.py", line 487, in 
patch_to_temp
    Hardlink.link_rp(diff_rorp, new, self.basis_root_rp)
  File "/usr/lib/python2.3/site-packages/rdiff_backup/Hardlink.py", line 116, 
in link_rp
    dest_rpath.hardlink(dest_link_rpath.path)
  File "/usr/lib/python2.3/site-packages/rdiff_backup/rpath.py", line 784, in 
hardlink
    self.conn.os.link(linkpath, self.path)
OSError: [Errno 2] No such file or directory

now because i've been having this problem and i couldn't figure out which
side was causing the trouble i actually had strace going on both sides.
the problem on the mirror side looks like this:

16:40:56 
lstat64("root/home/www/docroot/electricsheep/v2.4/gen/155/61018/rdiff-backup.tmp.563440",
 0xbfffe380) = -1 ENOENT (No such
file or directory) <0.000055>
16:40:56 
lstat64("root/home/www/docroot/electricsheep/v2.4/gen/155/61018/memory.dir", 
0xbfffe320) = -1 ENOENT (No such file or direc
tory) <0.000045>
16:40:56 
link("root/home/www/docroot/electricsheep/v2.4/gen/155/61018/memory.dir", 
"root/home/www/docroot/electricsheep/v2.4/gen/155
/61018/rdiff-backup.tmp.563440") = -1 ENOENT (No such file or directory) 
<0.000047>
16:40:56 write(1, "########## / root\n--------------"..., 1056) = 1056 
<0.000036>

rdiff-backup already knows that link is going to fail, and yet it goes
ahead and does it -- but more importantly is that it results in the
traceback above.  the final write is the beginning of it bailing out and
printing the traceback.

it would be preferable not to bail out on this error -- i'm pretty sure
what's happenned here is that the .../155/61018/ directory has disappeared
on the source (yeah i'm bad and backing up from a non-snapshot source).

-dean