Commit Graph

1946 Commits

Author SHA1 Message Date
Brian Behlendorf 35d3e32274 Use long holds in zvol_set_volsize()
Under Linux the zvol_set_volsize() function was originally written
to use dmu_objset_hold()/dmu_objset_rele().  Subsequently, the
dmu_objset_own()/dmu_objset_disown() interfaces were added but
the ZVOL code wasn't updated to take advantage of them.

This was never an issue but after the dsl_pool_config changes
the code now takes the config lock twice.  The cleanest solution
is to shift to using dmu_objset_own() which takes a long hold
on the dataset and does not hold the dsl pool lock.

This patch also slightly restructures the existing code such
that it more closely resembles the upstream Illumos code.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2039
2014-01-14 14:46:12 -08:00
Brian Behlendorf 0f62f3f9ab Disable GCCs aggressive loop optimization
GCC >+ 4.8's aggressive loop optimization breaks some of the iterators
over the dn_blkptr[] pseudo-array in dnode_phys. Since dn_blkptr[] is
defined as a single-element array, GCC believes an iterator can only
access index 0 and will unroll the loop into a single iteration.

One way to resolve the issue would be to cast the array to a pointer
and fix all the iterators that might break.  The only loop where it
is known to cause a problem is this loop in dmu_objset_write_ready():

    for (i = 0; i < dnp->dn_nblkptr; i++)
            bp->blk_fill += dnp->dn_blkptr[i].blk_fill;

In the common case where dn_nblkptr is 3, the loop is only executed a
single time and "i" is equal to 1 following the loop.

The specific breakage caused by this problem is that the blk_fill of
root block pointers wouldn't be set properly when more than one blkptr
is in use (when no indrect blocks are needed).

The simple reproducing sequence is:

zpool create tank /tank.img
zdb -ddddd tank 0

Notice that "fill=31", however, there are two L0 indirect blocks with
"F=31" and "F=5". The fill count should be 36 rather than 31. This
problem causes an assert to be hit in a simple "zdb tank" when built
with --enable-debug.

However, this approach was not taken because we need to be absolutely
sure we catch all instances of this unwanted optimization.  Therefore,
the build system has been updated to detect if GCC supports the
aggressive loop optimization.  If it does the optimization will be
explicitly disabled using the -fno-aggressive-loop-optimization option.

Original-fix-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2010
Closes #2051
2014-01-14 13:55:58 -08:00
Richard Yao cbe8e6198c Properly link zpool command to libblkid
31fc19399e incorrectly removed $(LIBBLKID)
from cmd/zpool/Makefile.am. This meant that the toolchain was not given
-lblkid, which resulted in the following build failure on Ubuntu 13.10:

/usr/bin/ld: zpool_vdev.o: undefined reference to symbol
'blkid_put_cache@@BLKID_1.0'
/lib/x86_64-linux-gnu/libblkid.so.1: error adding symbols: DSO missing
from command line
collect2: error: ld returned 1 exit status

That commit reworked various Makefile.am to follow best practices, so we
reintroduce $(LIBBLKID) in a manner consistent with that, rather than
explicitly reverting the change.

Reproduction of this issue was done on a Gentoo Linux system by
executing the following commands:

zfs create -o mountpoint=/mnt/ubuntu-13.10 rpool/ROOT/ubuntu-13.10
debootstrap --variant=buildd --arch amd64 saucy /mnt/ubuntu-13.10 http://archive.ubuntu.com/ubuntu/
mount -o bind /dev /mnt/ubuntu-13.10/dev/
mount -o bind /proc/ /mnt/ubuntu-13.10/proc/
mount -o bind /sys/ /mnt/ubuntu-13.10/sys/
cp /etc/resolv.conf /mnt/ubuntu-13.10/etc/
(cd /mnt/ubuntu-13.10/root/ && git clone git://github.com/zfsonlinux/zfs.git)
chroot /mnt/ubuntu-13.10/
apt-get install git autoconf libtool zlib1g-dev uuid-dev libblkid-dev
\#apt-get install alien fakeroot vim
cd /root/zfs
./autogen.sh
./configure --with-config=user --prefix=/usr
make

That will create a Ubuntu 13.10 chroot, fetch the sources and build
test. At this point, cmd/zpool/Makefile.am was modified and the
following commands were run to verify that the build issue was resolved:

git clean -xdf
./autogen.sh
./configure --with-config=user --prefix=/usr
make

Although it is not shown here, the absence of libblkid-dev enables ZFS
to build successfully without the patch. This could explain how this
escaped detection until recently. A test without libblkid-dev was done
to verify that the patch did not cause a regression in the absence of
libblkid:

apt-get remove libblkid-dev
git clean -xdf
./autogen.sh
./configure --with-config=user --prefix=/usr
make

Additionally, the commands themselves were tested against my live system
from within the chroot to ensure basic functionality. My live system had
corresponding kernel modules already installed and basic commands such
as `zpool list` and `zfs list` worked without incident. Lastly, this
patch was also build tested on Gentoo Linux, where it caused no
problems.

At time of writing, these steps can be used to reproduce these results
on any modern Linux system that has debootstrap installed. On Gentoo,
installing debootstrap can be done with `emerge dev-util/debootstrap`.
The current ZFSOnLinux HEAD revision as of writing is
fd23720ae1.  Once this is fixed in HEAD,
either that revision or another before this fix and after
31fc19399e will be needed to reproduce
this issue.

Lastly, it remains to be seen why the toolchains on the systems
performing regression tests did not catch this. This is not a
ZFS-specific issue, but it is something that we will want to explore in
the future.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2038
2014-01-14 10:27:17 -08:00
Brian Behlendorf 741304503a Prevent duplicate mnttab cache entries
Under Linux its possible to mount the same filesystem multiple
times in the namespace.  This can be done either with bind mounts
or simply with multiple mount points.  Unfortunately, the mnttab
cache code is implemented using an AVL tree which does not support
duplicate entries.  To avoid this issue this patch updates the
code to check for a duplicate entry before adding a new one.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Michael Martin <mgmartin.mgm@gmail.com>
Closes #2041
2014-01-14 10:27:12 -08:00
Brian Behlendorf fd23720ae1 Drain iput taskq outside z_teardown_lock
It's unsafe to drain the iput taskq while holding the z_teardown_lock
as a writer.  This is because when the last reference on an inode is
dropped it may still have pages which need to be written to disk.
This will be done through zpl_writepages which will acquire the
z_teardown_lock as a reader in ZFS_ENTER.  Therefore, if we're
holding the lock as a writer in zfs_sb_teardown the unmount will
deadlock.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Closes #1988
2014-01-09 15:54:08 -08:00
Brian Behlendorf 4fcc43790c Force LZ4_FORCE_SW_BITCOUNT for Sparc
This change was proposed for Sparc but it's not clear to me
why it's required.  Proper support exists in the lz4 code to
detect the endianness and the required builtins are available
for gcc.  Still I'm including the patch because it will only
impact Sparc and it may resolve a case which hasn't occured
to me.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: marku89 <mar42@kola.li>
Issue #1700
2014-01-09 15:54:03 -08:00
Brian Behlendorf b585bc4afa Fix zfs_getattr_fast types
On Sparc sp->blksize will be a 64-bit value which is then cast
incorrectly to a 32-bit value.  For big endian systems this
results in an incorrect value for sp->blksize.  To resolve the
problem local variables of the correct size are used and then
assigned to sp->blksize.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: marku89 <mar42@kola.li>
Issue #1700
2014-01-09 15:50:23 -08:00
Brian Behlendorf aa0218d6a1 Fix nvlist 'Bus Error' for Sparc
The mis-aligned memory accesses in nvpair_native_embedded() and
nvpair_native_embedded_array() will cause a 'Bus Error' for
architectures such as Sparc which not fully byte addressible.
To avoid this issue care is taken to avoid dereferencing the
potentially mis-aligned packed nvlist_t.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: marku89 <mar42@kola.li>
Issue #1700
2014-01-09 15:50:15 -08:00
Brian Behlendorf 7f89ae6ba0 Use local variable to read zp->z_mode
When accessing the zp->z_mode through the SA bulk interface we
expect that 64-bits are available to hold the result.  However,
on 32-bit platforms mode_t will only be 32-bits so we cannot
pass it to SA_ADD_BULK_ATTR().  Instead a local uint64_t variable
must be used and the result assigned to zp->z_mode.

This went unnoticed on 32-bit little endian platforms because
the bytes happen to end up in the correct 32-bits.  But on big
endian platforms like Sparc the zp->z_mode will always end up
set to zero.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: marku89 <mar42@kola.li>
Issue #1700
2014-01-09 15:50:11 -08:00
Brian Behlendorf d7ec8d4fd9 Define the needed ISA types for Sparc
Add the minimum required ISA types to support the Sparc
architecture.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: marku89 <mar42@kola.li>
Issue #1700
2014-01-09 15:49:59 -08:00
John Layman ecf3d9b8e6 Add ddt, ddt_entry, and l2arc_hdr caches
Back the allocations for ddt tables+entries and l2arc headers with
kmem caches.  This will reduce the cost of allocating these commonly
used structures and allow for greater visibility of them through the
/proc/spl/kmem/slab interface.

Signed-off-by: John Layman <jlayman@sagecloud.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1893
2014-01-07 10:33:11 -08:00
Brian Behlendorf 4dad7d91e2 Remove unconditional sharetab update
Removes the unconditional sharetab update when running any zfs
command. This means the sharetab might become out of date if
users are manually adding/removing shares with exportfs.  But
we shouldn't punish all callers to zfs in order to handle that
unlikely case. In the unlikely event we observe issues because
of this it can always be added back to just the share/unshare
call paths where we need an up to date sharetab.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Issue #845
2014-01-07 09:48:09 -08:00
Brian Behlendorf e07306687d Enable /etc/mtab cache to improve performance
Re-enable the /etc/mtab cache to prevent the zfs command from
having to repeatedly open and read from the /etc/mtab file.
Instead an AVL tree of the mounted filesystems is created and
used to vastly speed up lookups. This means that if non-zfs
filesystems are mounted concurrently the 'zfs mount' will not
immediately detect them.  In practice that will rarely happen
and even if it does the absolute worst case would be a failed
mount.  This was originally disabled out of an abundance of
paranoia.

NOTE: There may still be some parts of the code which do not
consult the mtab cache.  They should be updated to check the
mtab cache as they as discovered to be a problem.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Issue #845
2014-01-07 09:48:09 -08:00
Turbo Fredriksson 8c091798f2 Add UNSHARING of filesystems and EXPORTING pools
As a 'stop' action ensure the filesystem is unshared before
it is unmounted, just in case.  Additionally, export the pool
so it may be cleanly imported by a different host.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2003
2014-01-07 09:48:04 -08:00
Tim Chase fb8e608d9d Fix the creation of ZPOOL_HIST_CMD pool history entries.
Move the libzfs_fini() after the zpool_log_history() call so the
ZPOOL_HIST_CMD entry can get written.

Fix the handling of saved_poolname in zfsdev_ioctl()
which was broken as part of the stack-reduction work in
a168788053.

Since ZoL destroys the TSD data in which the previously successful
ioctl()'s pool name is stored following every vop, the ZFS_IOC_LOG_HISTORY
ioctl has a very important restriction: it can only successfully write
a long entry following a successful ioctl() if no intervening vops have
been performed.  Some of zfs subcommands do perform intervening vops and
to do the logging themselves. At the moment, the "create" and "clone"
subcommands have been modified appropriately.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1998
2014-01-07 09:00:26 -08:00
Tim Chase 5d862cb0d9 Properly handle updates of variably-sized SA entries.
During the update process in sa_modify_attrs(), the sizes of existing
variably-sized SA entries are obtained from sa_lengths[]. The case where
a variably-sized SA was being replaced neglected to increment the index
into sa_lengths[], so subsequent variable-length SAs would be rewritten
with the wrong length. This patch adds the missing increment operation
so all variably-sized SA entries are stored with their correct lengths.

Previously, a size-changing update of a variably-sized SA that occurred
when there were other variably-sized SAs in the bonus buffer would cause
the subsequent SAs to be corrupted.  The most common case in which this
would occur is when a mode change caused the ZPL_DACL_ACES entry to
change size when a ZPL_DXATTR (SA xattr) entry already existed.

The following sequence would have caused a failure when xattr=sa was in
force and would corrupt the bonus buffer:

	open(filename, O_WRONLY | O_CREAT, 0600);
	...
	lsetxattr(filename, ...);	/* create xattr SA */
	chmod(filename, 0650);		/* enlarges the ACL */

Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1978
2013-12-20 13:52:33 -08:00
Brian Behlendorf ac0340970c Register correct handlers for nvlist_{dup,pack,unpack}
This change is related to commit 81eaf15 which ensured the correct
allocation handlers were installed for nvlist_alloc().  The nvlist
functions nvlist_dup(), nvlist_pack(), and nvlist_unpack() suffer
from the same issue and have been updated accordingly.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1937
2013-12-20 13:52:28 -08:00
Matthew Thode 11b9ec23b9 Add full SELinux support
Four new dataset properties have been added to support SELinux.  They
are 'context', 'fscontext', 'defcontext' and 'rootcontext' which map
directly to the context options described in mount(8).  When one of
these properties is set to something other than 'none'.  That string
will be passed verbatim as a mount option for the given context when
the filesystem is mounted.

For example, if you wanted the rootcontext for a filesystem to be set
to 'system_u:object_r:fs_t' you would set the property as follows:

  $ zfs set rootcontext="system_u:object_r:fs_t" storage-pool/media

This will ensure the filesystem is automatically mounted with that
rootcontext.  It is equivalent to manually specifying the rootcontext
with the -o option like this:

  $ zfs mount -o rootcontext=system_u:object_r:fs_t storage-pool/media

By default all four contexts are set to 'none'.  Further information
on SELinux contexts is detailed in mount(8) and selinux(8) man pages.

Signed-off-by: Matthew Thode <prometheanfire@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes #1504
2013-12-19 10:37:31 -08:00
Michael Kjorling d1d7e2689d cstyle: Resolve C style issues
The vast majority of these changes are in Linux specific code.
They are the result of not having an automated style checker to
validate the code when it was originally written.  Others were
caused when the common code was slightly adjusted for Linux.

This patch contains no functional changes.  It only refreshes
the code to conform to style guide.

Everyone submitting patches for inclusion upstream should now
run 'make checkstyle' and resolve any warning prior to opening
a pull request.  The automated builders have been updated to
fail a build if when 'make checkstyle' detects an issue.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1821
2013-12-18 16:46:35 -08:00
Brian Behlendorf 8ffef572ed cstyle: Allow spaces in all comments
Update the cstyle.pl script to allow pictures in all comments not
just header comments.  Recent changes from Illumos such as d3cc8b1
have relocated various pictures in the standard block comments to
make the code more readable.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1821
2013-12-18 16:46:35 -08:00
Brian Behlendorf 351a26ddc0 cstyle: Exclude several files from 'make checkstyle'
The zfs_config.h header and *.mod.c files are both products
of the build process.  They must be excluded from the style
check because they are not part of the pristine source.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1821
2013-12-18 16:46:35 -08:00
John Wren Kennedy 2820bc49c5 Illumos #4208
4208 Typo in zfs_main.c: "posxiuser"

Reviewed by: Sonu Pillai <sonu.pillai@delphix.com>
Reviewed by: Will Guyette <will.guyette@delphix.com>
Reviewed by: Eric Diven <eric.diven@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/4208
  illumos/illumos-gate@f38cb554a5

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1986
2013-12-18 16:46:35 -08:00
Turbo Fredriksson fd8febbd1e Add zfs_send_corrupt_data module option
Tuning setting to ignore read/checksum errors when sending data.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1982
Issue #1897
2013-12-18 16:46:35 -08:00
Aaron Fineman 4788a01dbd Cause zfs.spec to place dracut files properly
This is an extension of commit ffb2111.  As the fedora conditional
has been added, this allows centos/rhel-6 to fall back to the
proper directory (/usr/share/dracut)

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1984
2013-12-18 16:46:35 -08:00
renelson a5f3665168 Handle acl flags from util-linux mount command
Add acl, noacl and posixacl to option_map, avoiding ENOENT error
case when mount from util-linux-2.24 execs mount.zfs with any of
those flags

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: renelson <bnelson@nelsonbe.com>
Issue #1968
2013-12-18 16:46:20 -08:00
renelson 758d35520b Fix grammar in parse_options() error message
A minor grammar error was corrected in in the parse_options()
error handling for the ENOENT case.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: renelson <bnelson@nelsonbe.com>
Issue #1968
2013-12-17 10:48:28 -08:00
Chunwei Chen 7dc71949f2 Fix z_sync_cnt decrement in zfs_close
The comment in zfs_close states that "Under Linux the zfs_close() hook
is not symmetric with zfs_open()". This is not true. zfs_open/zfs_close
is associated with every successful struct file creation/deletion, which
should always be balanced.

Here is an example of what's wrong:

Process A		B
	open(O_SYNC)
	z_sync_cnt = 1
			open(O_SYNC)
			z_sync_cnt = 2
	close()
	z_sync_cnt = 0

So z_sync_cnt is 0 even if B still has the file with O_SYNC.

Also moves the generic_file_open call before zfs_open to ensure that in
the case generic_file_open fails z_sync_cnt is not incremented.  This
is safe because generic_file_open has no side effects.

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1962
2013-12-17 10:28:27 -08:00
Brian Behlendorf c2d439dffd Silence e2fsck warning in zconfig.sh
When running zconfig.sh test 7 and 8 cause the following warning to
be printed to the console.  It's caused because we're snapshoting a
mounted ext2 filesystem which is not in a 'clean' state.  This is
to be expected since we have no guarentees about the on-disk
consistency of the filesystem.

EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended

To silence the warning and preserve the intent of these test cases
they have been updated to unmount the filesystem prior to snapshoting
them.  This ensures the ext2 filesystem is in a consistent state
when the snapshot is taken.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #1972
2013-12-16 09:46:10 -08:00
Brian Behlendorf ce37ebd2eb cstyle: zvol.c
Update zvol.c to conform to the style guidelines, verified by
running cstyle.pl on the source file.  This patch contains
no functional changes.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Issue #1821
2013-12-16 09:41:45 -08:00
Brian Behlendorf d17eab9ce0 Update zfs(8) Snapshots section
The Snapshots section of the zfs(8) man page is incorrect and should
have been updated as part of #1312.  Snapshots of volumes can be
accessed independently and their visibility is determined by the
'snapdev=hidden|visible' property.  This is analogous to the existing
'snapdir=hidden|visible' property.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #1921
2013-12-16 09:41:45 -08:00
Brian Behlendorf 2e0358cbca Sync /dev/zfs ioctl ordering
In order to minimize any future disruption caused by the addition
and removal /dev/zfs ioctls this patch makes the following changes.

1) Sync ZoL's ioctl ordering such that it matches Illumos.  For
   historic reasons the ZFS_IOC_DESTROY_SNAPS and ZFS_IOC_POOL_REGUID
   ioctls were out of order.

2) Move Linux and FreeBSD specific ioctls in to their own reserved
   ranges.  This allows us to preserve the existing ordering when
   new ioctls are added by either Illumos or FreeBSD.  When an
   ioctl is no longer needed it should be retired in place.

This change alters the ZFS user/kernel ABI so make sure you rebuild
both your user and kernel modules.  However, it should allow for a
much stabler interface going forward.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #1973
2013-12-16 09:41:39 -08:00
Brian Behlendorf ba6a24026c Remove ZFC_IOC_*_MINOR ioctl()s
Early versions of ZFS coordinated the creation and destruction
of device minors from userspace.  This was inherently racy and
in late 2009 these ioctl()s were removed leaving everything up
to the kernel.  This significantly simplified the code.

However, we never picked up these changes in ZoL since we'd
already significantly adjusted this code for Linux.  This patch
aims to rectify that by finally removing ZFC_IOC_*_MINOR ioctl()s
and moving all the functionality down in to the kernel.  Since
this cleanup will change the kernel/user ABI it's being done
in the same tag as the previous libzfs_core ABI changes.  This
will minimize, but not eliminate, the disruption to end users.

Once merged ZoL, Illumos, and FreeBSD will basically be back
in sync in regards to handling ZVOLs in the common code.  While
each platform must have its own custom zvol.c implemenation the
interfaces provided are consistent.

NOTES:

1) This patch introduces one subtle change in behavior which
   could not be easily avoided.  Prior to this change callers
   of 'zfs create -V ...' were guaranteed that upon exit the
   /dev/zvol/ block device link would be created or an error
   returned.  That's no longer the case.  The utilities will no
   longer block waiting for the symlink to be created.  Callers
   are now responsible for blocking, this is why a 'udev_wait'
   call was added to the 'label' function in scripts/common.sh.

2) The read-only behavior of a ZVOL now solely depends on if
   the ZVOL_RDONLY bit is set in zv->zv_flags.  The redundant
   policy setting in the gendisk structure was removed.  This
   both simplifies the code and allows us to safely leverage
   set_disk_ro() to issue a KOBJ_CHANGE uevent.  See the
   comment in the code for futher details on this.

3) Because __zvol_create_minor() and zvol_alloc() may now be
   called in a sync task they must use KM_PUSHPAGE.

References:
  illumos/illumos-gate@681d9761e8

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #1969
2013-12-16 09:15:57 -08:00
George Wilson dda12da9f1 Illumos #4121 vdev_label_init read only
4121 vdev_label_init should treat request as succeeded when pool
     is read only
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/4121
  illumos/illumos-gate@973c78e94b

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1863
2013-12-12 10:24:01 -08:00
Tim Chase 84b0aac5fd Fix atime handling.
Previously, the atime-modifying vnops called ZFS_ACCESSTIME_STAMP()
followed by zfs_inode_update() to update the atime.  However, since atimes
are cached in the znode for delayed writing, the zfs_inode_update()
function would effectively ignore the cached atime by reading it from
the SA.

This commit moves the updating of the atime in the inode into
zfs_tstamp_update_setup() which is called by the ZFS_ACCESSTIME_STAMP()
macro and eliminates the call to zfs_inode_update() in the atime-modifying
vnops.

It's possible the same thing could have been done directly in
zfs_inode_update() but I wasn't sure that it was safe in all cases where
it is called.

The effect is that atime handling is as if "strictatime" were selected;
even if the filesystem is mounted with "relatime".

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1949
2013-12-12 10:23:58 -08:00
Shen Yan 5cb65efe2c Fix zstream_t incorrect type
The DMU zfetch code organizes streams with lists not avl trees.  A
avl_node_t was mistakenly used for a list_node_t in the zstream_t
type.  This is incorrect (but harmless) and when unnoticed because:

1) The list functions explicitly cast the value preventing a warning,
2) sizeof(avl_node_t) >= sizeof(list_node_t) so no overrun occurs, and
3) The calculated offset is the same regardless of the type.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1946
2013-12-10 10:09:27 -08:00
david.chen be5db977ea Remove MAX when initializing arc_c_max
The MAX when initializing arc_c_max doesn't make any sense because
it hasn't been set anywhere before. Though, arc_c_max should be
implicitly set to zero when initializing arc_stats, so the MAX
doesn't make any difference.

The MAX was mistakenly left if place when the Illumos default
values were changed for Linux.

Signed-off-by: david.chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1941
2013-12-10 10:05:40 -08:00
Simon Guest 383efa5743 Fix multipath bug in vdev_id caused by inconsistent field numbering
The bug is caused by multipath output like this:

35000c50056bd77a7 dm-15 HP,MB3000FCWDH
size=2.7T features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=0 status=active
| `- 2:0:16:0 sdq  65:0    active undef running
`-+- policy='round-robin 0' prio=0 status=enabled
  `- 4:0:52:0 sdfp 130:176 active undef running

Note that the pipe symbols mean that the field numbering is different
between the sdq and sdfp lines.  The fix edits out the pipe symbols.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1692
2013-12-10 09:58:35 -08:00
Ned Bass b6e335bfc4 Revert "Use directory xattrs for symlinks"
This reverts commit 6a7c0ccca4.

A proper fix for Issue #1648 was landed under Issue #1890, so this is no
longer needed.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1648
2013-12-10 09:48:30 -08:00
James Pan 472e7c6085 sa_find_sizes() may compute wrong SA header size
Under the right conditions sa_find_sizes() will compute an incorrect
size of the system attribute (SA) header.  This causes a failed assertion
when the SA_HDR_SIZE_MATCH_LAYOUT() test returns false, and may lead
to corruption of SA data.

The bug presents itself when there are more than two variable-length SAs
of just the right size to fit in the bonus buffer of a dnode.  The
existing logic fails to account for the SA header space needed to store
the sizes of all the variable-length SAs.

A reproducer was possible on Linux by setting the xattr=sa dataset
property and storing xattrs on symbolic links (Issue #1648).  Note the
corrupt link target name:

$ zfs set xattr=sa tank/fish
$ cd /tank/fish
$ ln -fs 12345678901234567 link
$ setfattr -n trusted.0000000000000000000 -v 0x000000000000000000000000 -h link
$ setfattr -n trusted.1111111111111111111 -v 0x000000000000000000000000 -h link
$ ls -l link
lrwxrwxrwx 1 root root 17 Dec  6 15:40 link -> 90123456701234567

Commit 6a7c0ccca4 worked around this bug
by forcing xattr's on symlinks to be stored in directory format.  This
change implements a proper fix, so the workaround can now be reverted.

The reference link below contains a reproducer for FreeBSD.

References:
  http://lists.open-zfs.org/pipermail/developer/2013-November/000306.html

Ported-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1890
2013-12-10 09:48:15 -08:00
Turbo Fredriksson c1ab64d393 Update init script to allow verbose mounts
Allow verbose mounts to make is easier to monitor progress when
mounting a large number of filesystems.

This functionality is disabled by default.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1929
2013-12-06 10:59:35 -08:00
Turbo Fredriksson fc220e9ea5 Update init script to allow /dev/disk/by-id import
Many people prefer to use by-id at import time instead of using
the cache file.  This can be a much better solution than the cache
file in some environments so we're adding some infrastructure to
allow it.

This functionality is disabled by default.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1929
2013-12-06 10:59:09 -08:00
Brian Behlendorf 90ee9ed32f Fix 'zfs diff' shares error
When creating a dataset with ZoL a zsb->z_shares_dir ZAP object
will not be created because shares are unimplemented.  Instead ZoL
just sets zsb->z_shares_dir to zero to indicate there are no shares.

However, if you import a pool which was created with a different
ZFS implementation then the shares ZAP object may exist.  Code was
added to handle this case but it clearly wasn't sufficiently tested
with other ZFS pools.

There was a bug in the zpl_shares_getattr() function which passed
the wrong inode to zfs_getattr_fast() for the case where are shares
ZAP object does exist.  This causes an EIO to be returned to stat64()
which in turn causes 'zfs diff' to fail.

This fix is the pass the correct inode after a sucessful zfs_zget().
Additionally, only put away the references if we were able to get one.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Graham Booker <https://github.com/gbooker>
Signed-off-by: timemaster67 <https://github.com/timemaster67>
Closes #1426
Closes #481
2013-12-06 09:42:39 -08:00
Brian Behlendorf 99e349db92 Add module versioning
Use the standard Linux MODULE_VERSION macro to expose the installed
zavl, znvpair, zunicode, zcommon, zfs, and zpios module versions.
This will also automatically add a checksum of the .c files and
headers in "srcversion".  See:

  /sys/module/zavl/version
  /sys/module/zavl/srcversion
  /sys/module/znvpair/version
  /sys/module/znvpair/srcversion
  /sys/module/zunicode/version
  /sys/module/zunicode/srcversion
  /sys/module/zcommon/version
  /sys/module/zcommon/srcversion
  /sys/module/zfs/version
  /sys/module/zfs/srcversion
  /sys/module/zpios/version
  /sys/module/zpios/srcversion

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1923
2013-12-06 09:34:41 -08:00
Matthew Ahrens e8b96c6007 Illumos #4045 write throttle & i/o scheduler performance work
4045 zfs write throttle & i/o scheduler performance work

1. The ZFS i/o scheduler (vdev_queue.c) now divides i/os into 5 classes: sync
read, sync write, async read, async write, and scrub/resilver.  The scheduler
issues a number of concurrent i/os from each class to the device.  Once a class
has been selected, an i/o is selected from this class using either an elevator
algorithem (async, scrub classes) or FIFO (sync classes).  The number of
concurrent async write i/os is tuned dynamically based on i/o load, to achieve
good sync i/o latency when there is not a high load of writes, and good write
throughput when there is.  See the block comment in vdev_queue.c (reproduced
below) for more details.

2. The write throttle (dsl_pool_tempreserve_space() and
txg_constrain_throughput()) is rewritten to produce much more consistent delays
when under constant load.  The new write throttle is based on the amount of
dirty data, rather than guesses about future performance of the system.  When
there is a lot of dirty data, each transaction (e.g. write() syscall) will be
delayed by the same small amount.  This eliminates the "brick wall of wait"
that the old write throttle could hit, causing all transactions to wait several
seconds until the next txg opens.  One of the keys to the new write throttle is
decrementing the amount of dirty data as i/o completes, rather than at the end
of spa_sync().  Note that the write throttle is only applied once the i/o
scheduler is issuing the maximum number of outstanding async writes.  See the
block comments in dsl_pool.c and above dmu_tx_delay() (reproduced below) for
more details.

This diff has several other effects, including:

 * the commonly-tuned global variable zfs_vdev_max_pending has been removed;
use per-class zfs_vdev_*_max_active values or zfs_vdev_max_active instead.

 * the size of each txg (meaning the amount of dirty data written, and thus the
time it takes to write out) is now controlled differently.  There is no longer
an explicit time goal; the primary determinant is amount of dirty data.
Systems that are under light or medium load will now often see that a txg is
always syncing, but the impact to performance (e.g. read latency) is minimal.
Tune zfs_dirty_data_max and zfs_dirty_data_sync to control this.

 * zio_taskq_batch_pct = 75 -- Only use 75% of all CPUs for compression,
checksum, etc.  This improves latency by not allowing these CPU-intensive tasks
to consume all CPU (on machines with at least 4 CPU's; the percentage is
rounded up).

--matt

APPENDIX: problems with the current i/o scheduler

The current ZFS i/o scheduler (vdev_queue.c) is deadline based.  The problem
with this is that if there are always i/os pending, then certain classes of
i/os can see very long delays.

For example, if there are always synchronous reads outstanding, then no async
writes will be serviced until they become "past due".  One symptom of this
situation is that each pass of the txg sync takes at least several seconds
(typically 3 seconds).

If many i/os become "past due" (their deadline is in the past), then we must
service all of these overdue i/os before any new i/os.  This happens when we
enqueue a batch of async writes for the txg sync, with deadlines 2.5 seconds in
the future.  If we can't complete all the i/os in 2.5 seconds (e.g. because
there were always reads pending), then these i/os will become past due.  Now we
must service all the "async" writes (which could be hundreds of megabytes)
before we service any reads, introducing considerable latency to synchronous
i/os (reads or ZIL writes).

Notes on porting to ZFS on Linux:

- zio_t gained new members io_physdone and io_phys_children.  Because
  object caches in the Linux port call the constructor only once at
  allocation time, objects may contain residual data when retrieved
  from the cache. Therefore zio_create() was updated to zero out the two
  new fields.

- vdev_mirror_pending() relied on the depth of the per-vdev pending queue
  (vq->vq_pending_tree) to select the least-busy leaf vdev to read from.
  This tree has been replaced by vq->vq_active_tree which is now used
  for the same purpose.

- vdev_queue_init() used the value of zfs_vdev_max_pending to determine
  the number of vdev I/O buffers to pre-allocate.  That global no longer
  exists, so we instead use the sum of the *_max_active values for each of
  the five I/O classes described above.

- The Illumos implementation of dmu_tx_delay() delays a transaction by
  sleeping in condition variable embedded in the thread
  (curthread->t_delay_cv).  We do not have an equivalent CV to use in
  Linux, so this change replaced the delay logic with a wrapper called
  zfs_sleep_until(). This wrapper could be adopted upstream and in other
  downstream ports to abstract away operating system-specific delay logic.

- These tunables are added as module parameters, and descriptions added
  to the zfs-module-parameters.5 man page.

  spa_asize_inflation
  zfs_deadman_synctime_ms
  zfs_vdev_max_active
  zfs_vdev_async_write_active_min_dirty_percent
  zfs_vdev_async_write_active_max_dirty_percent
  zfs_vdev_async_read_max_active
  zfs_vdev_async_read_min_active
  zfs_vdev_async_write_max_active
  zfs_vdev_async_write_min_active
  zfs_vdev_scrub_max_active
  zfs_vdev_scrub_min_active
  zfs_vdev_sync_read_max_active
  zfs_vdev_sync_read_min_active
  zfs_vdev_sync_write_max_active
  zfs_vdev_sync_write_min_active
  zfs_dirty_data_max_percent
  zfs_delay_min_dirty_percent
  zfs_dirty_data_max_max_percent
  zfs_dirty_data_max
  zfs_dirty_data_max_max
  zfs_dirty_data_sync
  zfs_delay_scale

  The latter four have type unsigned long, whereas they are uint64_t in
  Illumos.  This accommodates Linux's module_param() supported types, but
  means they may overflow on 32-bit architectures.

  The values zfs_dirty_data_max and zfs_dirty_data_max_max are the most
  likely to overflow on 32-bit systems, since they express physical RAM
  sizes in bytes.  In fact, Illumos initializes zfs_dirty_data_max_max to
  2^32 which does overflow. To resolve that, this port instead initializes
  it in arc_init() to 25% of physical RAM, and adds the tunable
  zfs_dirty_data_max_max_percent to override that percentage.  While this
  solution doesn't completely avoid the overflow issue, it should be a
  reasonable default for most systems, and the minority of affected
  systems can work around the issue by overriding the defaults.

- Fixed reversed logic in comment above zfs_delay_scale declaration.

- Clarified comments in vdev_queue.c regarding when per-queue minimums take
  effect.

- Replaced dmu_tx_write_limit in the dmu_tx kstat file
  with dmu_tx_dirty_delay and dmu_tx_dirty_over_max.  The first counts
  how many times a transaction has been delayed because the pool dirty
  data has exceeded zfs_delay_min_dirty_percent.  The latter counts how
  many times the pool dirty data has exceeded zfs_dirty_data_max (which
  we expect to never happen).

- The original patch would have regressed the bug fixed in
  zfsonlinux/zfs@c418410, which prevented users from setting the
  zfs_vdev_aggregation_limit tuning larger than SPA_MAXBLOCKSIZE.
  A similar fix is added to vdev_queue_aggregate().

- In vdev_queue_io_to_issue(), dynamically allocate 'zio_t search' on the
  heap instead of the stack.  In Linux we can't afford such large
  structures on the stack.

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Ned Bass <bass6@llnl.gov>
Reviewed by: Brendan Gregg <brendan.gregg@joyent.com>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  http://www.illumos.org/issues/4045
  illumos/illumos-gate@69962b5647

Ported-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1913
2013-12-06 09:32:43 -08:00
Matthew Ahrens 384f8a09f8 Illumos #4347 ZPL can use dmu_tx_assign(TXG_WAIT)
Fix a lock contention issue by allowing threads not holding
ZPL locks to block when waiting to assign a transaction.

Porting Notes:

zfs_putpage() still uses TXG_NOWAIT, unlike the upstream version.  This
case may be a contention point just like zfs_write(), however it is not
safe to block here since it may be called during memory reclaim.

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Dan McDonald <danmcd@nexenta.com>
Reviewed by: Boris Protopopov <boris.protopopov@nexenta.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

References:
  https://www.illumos.org/issues/4347
  illumos/illumos-gate@e722410c49

Ported-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2013-12-06 09:30:51 -08:00
Richard Yao 729210564a Properly ignore bdi_setup_and_register return value
This broke compilation against Linux 3.13 and GCC 4.7.3.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1906
2013-12-04 14:53:45 -08:00
Brian Behlendorf 2e40f09410 Remove incorrect ASSERT in zfs_sb_teardown()
As part of zfs_sb_teardown() there is an assertion that all inodes
which are part of the zsb->z_all_znodes list have at least one
reference on them.  This is always true for the standard unmount
case but there are two other cases where it is not strictly true.

* zfs_ioc_rollback() - This is the most common case and it results
  from the fact that we aren't unmounting the filesystem.  During a
  normal unmount the MS_ACTIVE flag will be cleared on the super block
  causing iput_final() to evict the inode when its reference count
  drops to zero.  However, during a rollback MS_ACTIVE remains set
  since we're rolling back a live filesystem and need to preserve the
  existing super block.  This allows inodes with a zero reference count
  to stay in the cache thereby violating the assertion.

* destroy_inode() / zfs_sb_teardown() - There exists a small race
  between dropping the last reference on an inode and removing it from
  the zsb->z_all_znodes list.  This is unlikely to occur but could also
  trigger the assertion which is incorrect.  The inode may safely have
  a zero reference count in this case.

Since allowing a zero reference count on the inode is expected and
safe for both of these cases the simplest thing to do is remove the
ASSERT.  This code is only enabled for default builds so removing
this entirely is a very safe change.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #1417
Closes #1536
2013-12-02 15:58:58 -08:00
Richard Yao c8c8d1e7e5 Drive database update
Added:

Adata S396 (obtained from drive_id)
Apple MacBookAir3,1 SSD (obtained from drive_id)
Apple MacBookPro10,1 SSD (obtained from drive_id)
Intel 510 (obtained from drive_id)
Intel 710 (obtained from drive_id)
Intel DC S3500 (obtained from drive_id)
Netapp LUN (obtained from illumos user's sd.conf)
OCZ Agility 3 (obtained from drive_id)
OCZ Vertex (obtained from drive_id)
Samsung PM800 (obtained from drive_id)
Sandisk U100 (obtained from drive_id)
Sun Comstar (obtained from illumos user's sd.conf)

Notes:

1. The entries for the Intel DC S3500 were extrapolated from the 800GB
model's entry, which is "ATA     INTEL SSDSC2BB80".

2. The entires for the Intel 710 were extrapolated from the 120GG
model's entry, which is "ATA     INTEL SSDSA2BZ12".

3. The entires for the Intel 510 were extrapolated from the 250GB
model's entry, which is "ATA     INTEL SSDSC2MH25".

4. The entires for the Apple MacBookPro10,1 SSD were extrapolated from
the 512GB model's entry, which is "ATA     APPLE SSD SM512E". Google
searches suggest that this is a rebadged Samsung 830.

5. The entires for the Apple MacBookAir3,1 SSD were extrapolated from
the 128GB model's entry, which is "ATA     APPLE SSD TS128C". Google
searches suggest that this is a rebadged Kingston SSDNow V+ 100 (based
on Toshiba).

6. Sun Comstar is an iSCSI Target, so we cannot tell what the correct
sector size is through this method. We list it only for reference
purposes, but it is commented out. Similarly, it is not clear what the
right thing to do for Netapp is, so we comment it out.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1907
2013-12-02 14:07:26 -08:00
Tim Chase f707635fa5 Some nvlist allocations in hold processing need to use KM_PUSHPAGE.
This should hopefully catch the rest of the allocations in the
user hold/release processing that were missed by commit
65c67ea86e.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1852
Closes #1855
2013-12-02 14:02:46 -08:00
Etienne Dechamps 119a394ab0 Only commit the ZIL once in zpl_writepages() (msync() case).
Currently, using msync() results in the following code path:

    sys_msync -> zpl_fsync -> filemap_write_and_wait_range -> zpl_writepages -> write_cache_pages -> zpl_putpage

In such a code path, zil_commit() is called as part of zpl_putpage().
This means that for each page, the write is handed to the DMU, the ZIL
is committed, and only then do we move on to the next page. As one might
imagine, this results in atrocious performance where there is a large
number of pages to write: instead of committing a batch of N writes,
we do N commits containing one page each. In some extreme cases this
can result in msync() being ~700 times slower than it should be, as well
as very inefficient use of ZIL resources.

This patch fixes this issue by making sure that the requested writes
are batched and then committed only once. Unfortunately, the
implementation is somewhat non-trivial because there is no way to run
write_cache_pages in SYNC mode (so that we get all pages) without
making it wait on the writeback tag for each page.

The solution implemented here is composed of two parts:

 - I added a new callback system to the ZIL, which allows the caller to
   be notified when its ITX gets written to stable storage. One nice
   thing is that the callback is called not only in zil_commit() but
   in zil_sync() as well, which means that the caller doesn't have to
   care whether the write ended up in the ZIL or the DMU: it will get
   notified as soon as it's safe, period. This is an improvement over
   dmu_tx_callback_register() that was used previously, which only
   supports DMU writes. The rationale for this change is to allow
   zpl_putpage() to be notified when a ZIL commit is completed without
   having to block on zil_commit() itself.

 - zpl_writepages() now calls write_cache_pages in non-SYNC mode, which
   will prevent (1) write_cache_pages from blocking, and (2) zpl_putpage
   from issuing ZIL commits. zpl_writepages() will issue the commit
   itself instead of relying on zpl_putpage() to do it, thus nicely
   batching the writes. Note, however, that we still have to call
   write_cache_pages() again in SYNC mode because there is an edge case
   documented in the implementation of write_cache_pages() whereas it
   will not give us all dirty pages when running in non-SYNC mode. Thus
   we need to run it at least once in SYNC mode to make sure we honor
   persistency guarantees. This only happens when the pages are
   modified at the same time msync() is running, which should be rare.
   In most cases there won't be any additional pages and this second
   call will do nothing.

Note that this change also fixes a bug related to #907 whereas calling
msync() on pages that were already handed over to the DMU in a previous
writepages() call would make msync() block until the next TXG sync
instead of returning as soon as the ZIL commit is complete. The new
callback system fixes that problem.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1849
Closes #907
2013-11-23 15:08:29 -08:00