OpenZFS on Linux and FreeBSD
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Paul Dagnelie 63ce7b6fcf Illumos 6370 - ZFS send fails to transmit some holes
6370 ZFS send fails to transmit some holes
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Chris Williamson <chris.williamson@delphix.com>
Reviewed by: Stefan Ring <stefanrin@gmail.com>
Reviewed by: Steven Burgess <sburgess@datto.com>
Reviewed by: Arne Jansen <sensille@gmx.net>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  https://www.illumos.org/issues/6370
  https://github.com/illumos/illumos-gate/commit/286ef71

In certain circumstances, "zfs send -i" (incremental send) can produce
a stream which will result in incorrect sparse file contents on the
target.

The problem manifests as regions of the received file that should be
sparse (and read a zero-filled) actually contain data from a file that
was deleted (and which happened to share this file's object ID).

Note: this can happen only with filesystems (not zvols, because they do
not free (and thus can not reuse) object IDs).

Note: This can happen only if, since the incremental source (FromSnap),
a file was deleted and then another file was created, and the new file
is sparse (i.e. has areas that were never written to and should be
implicitly zero-filled).

We suspect that this was introduced by 4370 (applies only if hole_birth
feature is enabled), and made worse by 5243 (applies if hole_birth
feature is disabled, and we never send any holes).

The bug is caused by the hole birth feature. When an object is deleted
and replaced, all the holes in the object have birth time zero. However,
zfs send cannot tell that the holes are new since the file was replaced,
so it doesn't send them in an incremental. As a result, you can end up
with invalid data when you receive incremental send streams. As a
short-term fix, we can always send holes with birth time 0 (unless it's
a zvol or a dataset where we can guarantee that no objects have been
reused).

Ported-by: Steven Burgess <sburgess@datto.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #4369
Closes #4050
2016-03-15 10:01:48 -07:00
cmd Make arc_summary.py and dbufstat.py compatible with python3 2016-01-29 09:52:12 -08:00
config Linux 4.5 compat: xattr list handler 2016-01-29 09:52:13 -08:00
contrib Init script fixes 2015-09-29 15:27:14 -07:00
etc zfs-import: Perform verbatim import using cache file 2015-10-13 14:33:49 -07:00
include Linux 4.5 compat: xattr list handler 2016-01-29 09:52:13 -08:00
lib Fix maybe uninitialized 2016-01-29 14:11:11 -08:00
man Make zio_taskq_batch_pct user configurable 2015-12-23 17:29:34 -08:00
module Illumos 6370 - ZFS send fails to transmit some holes 2016-03-15 10:01:48 -07:00
rpm Prepare to tag zfs-0.6.5.5 2016-03-09 14:56:21 -08:00
scripts Use truncate instead of fallocate in ziltest.sh 2015-07-13 11:02:59 -07:00
udev Support parallel build trees (VPATH builds) 2015-07-17 13:42:51 -07:00
.gitignore Ignore *.{deb,rpm,tar.gz} files in the top directory. 2013-04-24 16:18:59 -07:00
.gitmodules Add zimport.sh compatibility test script 2014-02-21 12:10:31 -08:00
AUTHORS Add a missing > to AUTHORS 2014-09-02 14:18:53 -07:00
COPYRIGHT Update ZED copyright boilerplate 2015-05-11 15:07:00 -07:00
DISCLAIMER Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
META Prepare to tag zfs-0.6.5.5 2016-03-09 14:56:21 -08:00
Makefile.am Support parallel build trees (VPATH builds) 2015-07-17 13:42:51 -07:00
OPENSOLARIS.LICENSE Add CDDL license file 2008-12-01 14:49:34 -08:00
README.markdown Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
TEST Follow 0/-E convention for module load errors 2015-12-23 17:29:35 -08:00
autogen.sh build: do not call boilerplate ourself 2013-04-02 10:55:20 -07:00
configure.ac Move dracut directory to contrib 2015-07-09 13:59:37 -07:00
copy-builtin Fix --enable-linux-builtin 2015-12-23 17:29:34 -08:00
zfs-script-config.sh.in Initial implementation of zed (ZFS Event Daemon) 2014-04-02 13:10:03 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

README.markdown

Native ZFS for Linux!

ZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the Illumos community.

ZFS on Linux, which is also known as ZoL, is currently feature complete. It includes fully functional and stable SPA, DMU, ZVOL, and ZPL layers.

Full documentation for installing ZoL on your favorite Linux distribution can be found at: http://zfsonlinux.org