rsync - Apr 2010 - DO NOT REPLY [Bug 7337] New: sparse files not equally sparse on destination

https://bugzilla.samba.org/show_bug.cgi?id=7337

           Summary: sparse files not equally sparse on destination
           Product: rsync
           Version: 3.0.7
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: brian at interlinx.bc.ca
         QAContact: rsync-qa at samba.org


If I create a 0 block sparse file and then rsync it, it's not 0 blocks on
the
copy.  Here's a reproducer:

$ rsync --version
rsync  version 3.0.7  protocol version 30
Copyright (C) 1996-2009 by Andrew Tridgell, Wayne Davison, and others.
Web site: http://rsync.samba.org/
Capabilities:
    64-bit files, 64-bit inums, 32-bit timestamps, 64-bit long ints,
    socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
    append, ACLs, xattrs, iconv, symtimes

rsync comes with ABSOLUTELY NO WARRANTY.  This is free software, and you
are welcome to redistribute it under certain conditions.  See the GNU
General Public Licence for details.
$ dd if=/dev/zero of=/tmp/sparse_file bs=1M count=0 seek=5
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.000125157 s, 0.0 kB/s
$ ls -ls /tmp/sparse_file
0 -rw-r--r-- 1 brian brian 5242880 2010-04-08 10:33 /tmp/sparse_file
$ rsync --sparse /tmp/sparse_file /var/tmp
$ ls -ls /var/tmp/sparse_file 
12 -rw-r--r-- 1 brian brian 5242880 2010-04-08 10:34 /var/tmp/sparse_file

Notice the source file is 0 blocks long and the destination is 12 blocks long.

Gnutar on the other hand makes the destination as sparse as the source:

$ tar CcSvf /tmp - sparse_file | tar Cxvf /var/tmp/ -
sparse_file
sparse_file
$ ls -ls /var/tmp/sparse_file 
0 -rw-r--r-- 1 brian brian 5242880 2010-04-08 10:33 /var/tmp/sparse_file


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https://bugzilla.samba.org/show_bug.cgi?id=7337


wayned at samba.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED




------- Comment #1 from wayned at samba.org  2010-04-24 13:20 CST -------
Rsync currently writes out a 0-byte into the final byte of the file when a file
is sparse clear through to the end.  We should probably change that to use
ftruncate() (when available) instead.  I'll give that a try soon, unless
someone beats me to the punch.


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ildar at altlinux.ru changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ildar at altlinux.ru




------- Comment #2 from ildar at altlinux.ru  2010-11-05 14:42 CST -------
You might want to use "du" to see how much space a file spends. It is
0 for
both source and destination files.

Or did I miss something?


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wayned at samba.org changed:

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




------- Comment #3 from wayned at samba.org  2010-11-06 12:18 CST -------
As long as the extra space was caused by the final block getting allocated when
it shouldn't have been, this should now be fixed in git.  If the file's
real
blocksize vs its rsync blocksize caused some unallocated blocks to not get
found, that is not something that can be easily fixed.


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