Commit torvalds/linux@4246a0b63b
("block: add a bi_error field to struct bio") dropped the error
argument from bio_endio in favor of newly introduced bio->bi_error.
This also replaces bio->bi_flags value BIO_UPTODATE.
bio_endio was a 3 argument function until Linux 2.6.24, which made it
a 2 argument function, and now the prototype has changed yet again to
a 1 argument function. Support for pre 2.6.24 kernels was already
dropped with 37f9dac592 ("zvol processing should use struct bio")
which assumed the 2 argument version in zvol_request(). Remaining code
to support the 3 argument version is hereby removed.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Issue #3799
zfsonlinux/zfs@e20cd6f7a8 caused us to
lose IO accounting on zvols. When I originally wrote that last year, the
symbols we needed to maintain IO accounting were GPL exported, but
torvalds/linux@394ffa503b provided
suitable symbols for restoring this functionality 4 months later. We
can call them to restore the IO accounting on Linux 3.19 and later as
well as any older kernels where that patch is backported.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3741
Internally, zvols are files exposed through the block device API. This
is intended to reduce overhead when things require block devices.
However, the ZoL zvol code emulates a traditional block device in that
it has a top half and a bottom half. This is an unnecessary source of
overhead that does not exist on any other OpenZFS platform does this.
This patch removes it. Early users of this patch reported double digit
performance gains in IOPS on zvols in the range of 50% to 80%.
Comments in the code suggest that the current implementation was done to
obtain IO merging from Linux's IO elevator. However, the DMU already
does write merging while arc_read() should implicitly merge read IOs
because only 1 thread is permitted to fetch the buffer into ARC. In
addition, commercial ZFSOnLinux distributions report that regular files
are more performant than zvols under the current implementation, and the
main consumers of zvols are VMs and iSCSI targets, which have their own
elevators to merge IOs.
Some minor refactoring allows us to register zfs_request() as our
->make_request() handler in place of the generic_make_request()
function. This eliminates the layer of code that broke IO requests on
zvols into a top half and a bottom half. This has several benefits:
1. No per zvol spinlocks.
2. No redundant IO elevator processing.
3. Interrupts are disabled only when actually necessary.
4. No redispatching of IOs when all taskq threads are busy.
5. Linux's page out routines will properly block.
6. Many autotools checks become obsolete.
An unfortunate consequence of eliminating the layer that
generic_make_request() is that we no longer calls the instrumentation
hooks for block IO accounting. Those hooks are GPL-exported, so we
cannot call them ourselves and consequently, we lose the ability to do
IO monitoring via iostat. Since zvols are internally files mapped as
block devices, this should be okay. Anyone who is willing to accept the
performance penalty for the block IO layer's accounting could use the
loop device in between the zvol and its consumer. Alternatively, perf
and ftrace likely could be used. Also, tools like latencytop will still
work. Tools such as latencytop sometimes provide a better view of
performance bottlenecks than the traditional block IO accounting tools
do.
Lastly, if direct reclaim occurs during spacemap loading and swap is on
a zvol, this code will deadlock. That deadlock could already occur with
sync=always on zvols. Given that swap on zvols is not yet production
ready, this is not a blocker.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Pre-2.6.37 kernels support REQ_FUA in request flags, but not in BIO
flags. zvols are the only consumer of VDEV_REQ_FUA and since they are
passed requests, they should be obey the REQ_FUA flag like later
kernels. This optimization will only matter on 2.6.36 and 2.6.37 because
the zvol rework changes things to use bio, where we no longer are able
to distinguish on earlier kernels
Signed-off-by: Richard Yao <ryao@gentoo.org>
This is needed for supporting kernels earlier than 2.6.30. Support for
those kernels was dropped, so we can safely remove this check.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This is needed for supporting kernels earlier than 2.6.30. Support for
those kernels was dropped, so we can safely remove this check.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Re-factor the .zfs/snapshot auto-mouting code to take in to account
changes made to the upstream kernels. And to lay the groundwork for
enabling access to .zfs snapshots via NFS clients. This patch makes
the following core improvements.
* All actively auto-mounted snapshots are now tracked in two global
trees which are indexed by snapshot name and objset id respectively.
This allows for fast lookups of any auto-mounted snapshot regardless
without needing access to the parent dataset.
* Snapshot entries are added to the tree in zfsctl_snapshot_mount().
However, they are now removed from the tree in the context of the
unmount process. This eliminates the need complicated error logic
in zfsctl_snapshot_unmount() to handle unmount failures.
* References are now taken on the snapshot entries in the tree to
ensure they always remain valid while a task is outstanding.
* The MNT_SHRINKABLE flag is set on the snapshot vfsmount_t right
after the auto-mount succeeds. This allows to kernel to unmount
idle auto-mounted snapshots if needed removing the need for the
zfsctl_unmount_snapshots() function.
* Snapshots in active use will not be automatically unmounted. As
long as at least one dentry is revalidated every zfs_expire_snapshot/2
seconds the auto-unmount expiration timer will be extended.
* Commit torvalds/linux@bafc9b7 caused snapshots auto-mounted by ZFS
to be immediately unmounted when the dentry was revalidated. This
was a consequence of ZFS invaliding all snapdir dentries to ensure that
negative dentries didn't mask new snapshots. This patch modifies the
behavior such that only negative dentries are invalidated. This solves
the issue and may result in a performance improvement.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3589Closes#3344Closes#3295Closes#3257Closes#3243Closes#3030Closes#2841
Starting from linux-2.6.37, {kmap,kunmap}_atomic takes 1 argument instead of 2.
We use zfs_{kmap,kunmap}_atomic as wrappers and always take 2 argument, but
ignore the 2nd for newer kernel.
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The vfs_compat.h header should include the linux/backing-dev.h header
because it depends on the bdi_* functions defined there. In previous
kernels this header was being indirectly included which prevented a
build failure.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes#3596
Commit f4af6bb783 which added support
for REQ_FAILFAST_MASK but the new autoconf test didn't use the same
preprocessor macro name as the code did.
The effect is that FAILFAST mode has not been enabled for ZoL in any
post-2.6.35 kernel.
Retire the HAVE_BIO_RW_FAILFAST interface used in pre-2.6.28 kernels.
Raise an error condition if the FAILFAST interface can't be detected.
Signed-off-by: Tim Chase <tim@onlight.com
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3386
The 'capabilities' argument which was passed to bdi_setup_and_register()
has been removed. File systems should no longer pass BDI_CAP_MAP_COPY.
For our purposes this means there are now three different interfaces
which must be handled. A zpl_bdi_setup_and_register() wrapper function
has been introduced to provide a single interface to the ZPL code.
* 2.6.32 - 2.6.33, bdi_setup_and_register() is not exported.
* 2.6.34 - 3.19, bdi_setup_and_register() takes 3 arguments.
* 4.0 - x.y, bdi_setup_and_register() takes 2 arguments.
I've also taken this opportunity to remove HAVE_BDI because kernels
older then 2.6.32 are no longer supported. All kernels newer than
this will have one of the above interfaces.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Closes#3128
struct access f->f_dentry->d_inode was replaced by accessor function
file_inode(f)
Signed-off-by: Joerg Thalheim <joerg@higgsboson.tk>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3084
This is the upstream component of work that enables preliminary support
for building Gentoo's ZFS packaging on other Linux systems via Gentoo
Prefix.
Signed-off-by: Richard Yao <richard.yao@clusterhq.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2641
Modify the code to use the utsname() kernel function rather than
a global variable. This results is cleaner more portable code
because utsname() is already provided by the kernel and can be
easily emulated in user space via uname(2). This means that it
will behave consistently in both contexts.
This is also has the benefit that it allows the removal of a few
_KERNEL pre-processor conditions. And it also is a pre-requisite
for a proper FUSE port because we need to provide a valid utsname.
Finally, it allows us to remove this functionality from the SPL
and all the related compatibility code.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2757
We should have included sys/taskq.h directly because we use the taskq
code here, but we instead had files that included sys/taskq.h also
include sys/kmem.h, which happened to include sys/taskq.h. sys/kmem.h no
longer does this, so we must define the include as we should
have done in the first place.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#2411
Some kernel definitions were buried inside the #if... #endif logic for
ACLs. When ACLs are not available these definitions get lost causing
the build to fail.
Signed-off-by: Chris Wedgwood <cw@f00f.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#2349
We add support for lsattr and chattr to resolve a regression caused
by 88c283952f that broke Python's
xattr.list(). That changet broke Gentoo Portage's FEATURES=xattr,
which depended on Python's xattr.list().
Only attributes common to both Solaris and Linux are supported. These
are 'a', 'd' and 'i' in Linux's lsattr and chattr commands. File
attributes exclusive to Solaris are present in the ZFS code, but cannot
be accessed or modified through this method. That was the case prior to
this patch. The resolution of issue zfsonlinux/zfs#229 should implement
some method to permit access and modification of Solaris-specific
attributes.
References:
https://bugs.gentoo.org/show_bug.cgi?id=483516
Original-patch-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1691
rq_for_each_segment changed from taking bio_vec * to taking bio_vec.
We provide rq_for_each_segment4 which takes both.
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2124
bi_sector, bi_size and bi_idx are moved from bio to bio->bi_iter.
This patch creates BIO_BI_*(bio) macros to hide the differences.
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2124
posix_acl_{create,chmod} is changed to __posix_acl_{create_chmod}
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2124
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
The required Posix ACL interfaces are only available for kernels
with CONFIG_FS_POSIX_ACL defined. Therefore, only enable Posix
ACL support for these kernels. All major distribution kernels
enable CONFIG_FS_POSIX_ACL by default.
If your kernel does not support Posix ACLs the following warning
will be printed at ZFS module load time.
"ZFS: Posix ACLs disabled by kernel"
Signed-off-by: Massimo Maggi <me@massimo-maggi.eu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1825
This change adds support for Posix ACLs by storing them as an xattr
which is common practice for many Linux file systems. Since the
Posix ACL is stored as an xattr it will not overwrite any existing
ZFS/NFSv4 ACLs which may have been set. The Posix ACL will also
be non-functional on other platforms although it may be visible
as an xattr if that platform understands SA based xattrs.
By default Posix ACLs are disabled but they may be enabled with
the new 'aclmode=noacl|posixacl' property. Set the property to
'posixacl' to enable them. If ZFS/NFSv4 ACL support is ever added
an appropriate acltype will be added.
This change passes the POSIX Test Suite cleanly with the exception
of xacl/00.t test 45 which is incorrect for Linux (Ext4 fails too).
http://www.tuxera.com/community/posix-test-suite/
Signed-off-by: Massimo Maggi <me@massimo-maggi.eu>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#170
The approach taken was the rework zfs_holey() as little as
possible and then just wrap the code as needed to ensure
correct locking and error handling.
Tested with xfstests 285 and 286. All tests pass except for
7-9 of 285 which try to reserve blocks first via fallocate(2)
and fail because fallocate(2) is not yet supported.
Note that the filp->f_lock spinlock did not exist prior to
Linux 2.6.30, but we avoid the need for autotools check by
virtue of the fact that SEEK_DATA/SEEK_HOLE support was not
added until Linux 3.1.
An autoconf check was added for lseek_execute() which is
currently a private function but the expectation is that it
will be exported perhaps as early as Linux 3.11.
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1384
Until these hooks are fully implemented return the expected
-EOPNOTSUPP error to indicate they are not functional. This
allows test suites such as xfstests to cleanly skip testing
this functionality until it's implemented.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #229
The definition of zfs_vdev_holder casts VDEV_HOLDER into a function pointer
passing to linux kernel's block layer function blkdev_get_by_path.
However current VDEV_HOLDER is defined to be wider than 32 bits and the compiler
warns about potential overflows. Instead of specifying different values for 32-bit and
64-bit systems using ifdefs, choose the common factor 32-bit addresses.
Redefine VDEV_HOLDER to 0x2401de7("zholder") here.
Signed-off-by: Ying Zhu <casualfisher@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1520
Install the common zfs kernel development headers under
/usr/src/zfs-<version>/ rather than in a kernel specific
directory. The kernel specific build products such as
zfs_config.h and Modules.symvers are left installed under
/usr/src/zfs-<version>/<kernel>.
This was done to be consistent with where dkms expects
kernel module source to be packaged. It also allows for
a common zfs-kmod-devel package which includes the headers,
and per-kernel zfs-kmod-devel-<kernel> packages.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The issue with hot spares in ZoL is because it opens all leaf
vdevs exclusively (O_EXCL). On Linux, exclusive opens cause
subsequent exclusive opens to fail with EBUSY.
This could be resolved by not opening any of the devices
exclusively, which is what Illumos does, but the additional
protection offered by exclusive opens is desirable. It cleanly
prevents you from accidentally adding an in-use non-ZFS device
to your pool.
To fix this we very slightly relaxed the usage of O_EXCL in
the following ways.
1) Functions which open the device but only read had the
O_EXCL flag removed and were updated to use O_RDONLY.
2) A common holder was added to the vdev disk code. This
allow the ZFS code to internally open the device multiple
times but non-ZFS callers may not.
3) An exception was added to make_disks() for hot spare when
creating partition tables. For hot spare devices which
are already opened exclusively we skip creating the partition
table because this must already have been done when the disk
was originally added as a hot spare.
Additional minor changes include fixing check_in_use() to use
a partition instead of a slice suffix. And is_spare() was moved
above make_disks() to avoid adding a forward reference.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#250
It's doubtful many people were impacted by this but commit 6c28567
accidentally broke ZFS builds for 2.6.26 and earlier kernels. This
commit depends on the lookup_bdev() function which exists in 2.6.26
but wasn't exported until 2.6.27.
The availability of the function isn't critical so a wrapper is
introduced which returns ERR_PTR(-ENOTSUP) when the function isn't
defined. This will have the effect of causing zvol_is_zvol() to
always fail for 2.6.26 kernels. This in turn means vdevs will
always get opened concurrently which is good for normal usage.
This will only become an issue if your using a zvol as a vdev in
another pool. In which case you really should be using a newer
kernel anyway.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1205
Added d_clear_d_op() helper function which clears some flags and the
registered dentry->d_op table. This is required because d_set_d_op()
issues a warning when the dentry operations table is already set.
For the .zfs control directory to work properly we must be able to
override the default operations table and register custom .d_automount
and .d_revalidate callbacks.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes#1230
Rolling back a mounted filesystem with open file handles and
cached dentries+inodes never worked properly in ZoL. The
major issue was that Linux provides no easy mechanism for
modules to invalidate the inode cache for a file system.
Because of this it was possible that an inode from the previous
filesystem would not get properly dropped from the cache during
rolling back. Then a new inode with the same inode number would
be create and collide with the existing cached inode. Ideally
this would trigger an VERIFY() but in practice the error wasn't
handled and it would just NULL reference.
Luckily, this issue can be resolved by sprucing up the existing
Solaris zfs_rezget() functionality for the Linux VFS.
The way it works now is that when a file system is rolled back
all the cached inodes will be traversed and refetched from disk.
If a version of the cached inode exists on disk the in-core
copy will be updated accordingly. If there is no match for that
object on disk it will be unhashed from the inode cache and
marked as stale.
This will effectively make the inode unfindable for lookups
allowing the inode number to be immediately recycled. The inode
will then only be accessible from the cached dentries. Subsequent
dentry lookups which reference a stale inode will result in the
dentry being invalidated. Once invalidated the dentry will drop
its reference on the inode allowing it to be safely pruned from
the cache.
Special care is taken for negative dentries since they do not
reference any inode. These dentires will be invalidate based
on when they were added to the dentry cache. Entries added
before the last rollback will be invalidate to prevent them
from masking real files in the dataset.
Two nice side effects of this fix are:
* Removes the dependency on spl_invalidate_inodes(), it can now
be safely removed from the SPL when we choose to do so.
* zfs_znode_alloc() no longer requires a dentry to be passed.
This effectively reverts this portition of the code to its
upstream counterpart. The dentry is not instantiated more
correctly in the Linux ZPL layer.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes#795
Lookups in the snapshot control directory for an existing snapshot
fail with ENOENT if an earlier lookup failed before the snapshot was
created. This is because the earlier lookup causes a negative dentry
to be cached which is never invalidated.
The bug can be reproduced as follows (the second ls should succeed):
$ ls /tank/.zfs/snapshot/s
ls: cannot access /tank/.zfs/snapshot/s: No such file or directory
$ zfs snap tank@s
$ ls /tank/.zfs/snapshot/s
ls: cannot access /tank/.zfs/snapshot/s: No such file or directory
To remedy this, always invalidate cached dentries in the snapshot
control directory. Since these entries never exist on disk there is
no significant performance penalty for the extra lookups.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1192
Use the bdev_physical_block_size() interface to determine the
minimize write size which can be issued without incurring a
read-modify-write operation. This is used to set the ashift
correctly to prevent a performance penalty when using AF hard
disks.
Unfortunately, this interface isn't entirely reliable because
it's not uncommon for disks to misreport this value. For this
reason you may still need to manually set your ashift with:
zpool create -o ashift=12 ...
The solution to this in the upstream Illumos source was to add
a white list of known offending drives. Maintaining such a list
will be a burden, but it still may be worth doing if we can
detect a large number of these drives. This should be considered
as future work.
Reported-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#916
Use .mkdir instead of .create in 3.3 compatibility check. Linux 3.6
modifies inode_operations->create's function prototype. This causes
an autotools Linux 3.3. compatibility check for a function prototype
change in create, mkdir and mknode to fail. Since mkdir and mknode
are unchanged, we modify the check to examine it instead.
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #873
As of Linux commit 9249e17fe094d853d1ef7475dd559a2cc7e23d42 the
mount flags are now passed to sget() so they can be used when
initializing a new superblock.
ZFS never uses sget() in this fashion so we can simply pass a
zero and add a zpl_sget() compatibility wrapper.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #873
This reverts commit 395350c85d which
accidentally introduced issue #955.
Pools using AF drives which were originally created with a sector
size of 512 bytes will now be correctly detected to have physical
sector size of 4096. This is desirable for a new pool, however for
an existing pool abruptly changing the sector size causes problems.
For this reason, this change is being reverted until the additional
logic can be added to detect the existing pool case. Existing
pools must use the ashift size stored in the label regardless of
what the disk reports. This is critical for compatibility.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #955
Use the bdev_physical_block_size() interface to determine the
minimize write size which can be issued without incurring a
read-modify-write operation. This is used to set the ashift
correctly to prevent a performance penalty when using AF hard
disks.
Unfortunately, this interface isn't entirely reliable because
it's not uncommon for disks to misreport this value. For this
reason you may still need to manually set your ashift with:
zpool create -o ashift=12 ...
The solution to this in the upstream Illumos source was to add
a while list of known offending drives. Maintaining such a list
will be a burden, but it still may be worth doing if we can
detect a large number of these drives. This should be considered
as future work.
Reported-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#916
Remove all of the generated autotools products from the repository
and update the .gitignore files accordingly.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#718
Currently, zvols have a discard granularity set to 0, which suggests to
the upper layer that discard requests of arbirarily small size and
alignment can be made efficiently.
In practice however, ZFS does not handle unaligned discard requests
efficiently: indeed, it is unable to free a part of a block. It will
write zeros to the specified range instead, which is both useless and
inefficient (see dnode_free_range).
With this patch, zvol block devices expose volblocksize as their discard
granularity, so the upper layer is aware that it's not supposed to send
discard requests smaller than volblocksize.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#862
The end_writeback() function was changed by moving the call to
inode_sync_wait() earlier in to evict(). This effecitvely changes
the ordering of the sync but it does not impact the details of
the zfs implementation.
However, as part of this change end_writeback() was renamed to
clear_inode() to reflect the new semantics. This change does
impact us and clear_inode() now maps to end_writeback() for
kernels prior to 3.5.
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#784
The vmtruncate_range() support has been removed from the kernel in
favor of using the fallocate method in the file_operations table.
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #784
The export_operations member ->encode_fh() has been updated to
take both the child and parent inodes. This interface used to
take the child dentry and a bool describing if the parent is needed.
NOTE: While updating this code I noticed that we do not currently
cleanly handle the case where we're passed a connectable parent.
This code should be audited to make sure we're doing the right thing.
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #784
Currently, zpool online -e (dynamic vdev expansion) doesn't work on
whole disks because we're invoking ioctl(BLKRRPART) from userspace
while ZFS still has a partition open on the disk, which results in
EBUSY.
This patch moves the BLKRRPART invocation from the zpool utility to the
module. Specifically, this is done just before opening the device in
vdev_disk_open() which is called inside vdev_reopen(). This requires
jumping through some hoops to get to the disk device from the partition
device, and to make sure we can still open the partition after the
BLKRRPART call.
Note that this new code path is triggered on dynamic vdev expansion
only; other actions, like creating a new pool, are unchanged and still
call BLKRRPART from userspace.
This change also depends on API changes which are available in 2.6.37
and latter kernels. The build system has been updated to detect this,
but there is no compatibility mode for older kernels. This means that
online expansion will NOT be available in older kernels. However, it
will still be possible to expand the vdev offline.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#808
torvalds/linux@adc0e91ab1 introduced
introduced d_make_root() as a replacement for d_alloc_root(). Further
commits appear to have removed d_alloc_root() from the Linux source
tree. This causes the following failure:
error: implicit declaration of function 'd_alloc_root'
[-Werror=implicit-function-declaration]
To correct this we update the code to use the current d_make_root()
interface for readability. Then we introduce an autotools check
to determine if d_make_root() is available. If it isn't then we
define some compatibility logic which used the older d_alloc_root()
interface.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#776
The mode argument of iops->create()/mkdir()/mknod() was changed from
an 'int' to a 'umode_t'. To prevent a compiler warning an autoconf
check was added to detect the API change and then correctly set a
zpl_umode_t typedef. There is no functional change.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#701
Allow rigorous (and expensive) tx validation to be enabled/disabled
indepentantly from the standard zfs debugging. When enabled these
checks ensure that all txs are constructed properly and that a dbuf
is never dirtied without taking the correct tx hold.
This checking is particularly helpful when adding new dmu consumers
like Lustre. However, for established consumers such as the zpl
with no known outstanding tx construction problems this is just
overhead.
--enable-debug-dmu-tx - Enable/disable validation of each tx as
--disable-debug-dmu-tx it is constructed. By default validation
is disabled due to performance concerns.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Add support for the .zfs control directory. This was accomplished
by leveraging as much of the existing ZFS infrastructure as posible
and updating it for Linux as required. The bulk of the core
functionality is now all there with the following limitations.
*) The .zfs/snapshot directory automount support requires a 2.6.37
or newer kernel. The exception is RHEL6.2 which has backported
the d_automount patches.
*) Creating/destroying/renaming snapshots with mkdir/rmdir/mv
in the .zfs/snapshot directory works as expected. However,
this functionality is only available to root until zfs
delegations are finished.
* mkdir - create a snapshot
* rmdir - destroy a snapshot
* mv - rename a snapshot
The following issues are known defeciences, but we expect them to
be addressed by future commits.
*) Add automount support for kernels older the 2.6.37. This should
be possible using follow_link() which is what Linux did before.
*) Accessing the .zfs/snapshot directory via NFS is not yet possible.
The majority of the ground work for this is complete. However,
finishing this work will require resolving some lingering
integration issues with the Linux NFS kernel server.
*) The .zfs/shares directory exists but no futher smb functionality
has yet been implemented.
Contributions-by: Rohan Puri <rohan.puri15@gmail.com>
Contributiobs-by: Andrew Barnes <barnes333@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#173
Allow a source rpm to be rebuilt with debugging enabled. This
avoids the need to have to manually modify the spec file. By
default debugging is still largely disabled. To enable specific
debugging features use the following options with rpmbuild.
'--with debug' - Enables ASSERTs
# For example:
$ rpmbuild --rebuild --with debug zfs-modules-0.6.0-rc6.src.rpm
Additionally, ZFS_CONFIG has been added to zfs_config.h for
packages which build against these headers. This is critical
to ensure both zfs and the dependant package are using the same
prototype and structure definitions.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
DISCARD (REQ_DISCARD, BLKDISCARD) is useful for thin provisioning.
It allows ZVOL clients to discard (unmap, trim) block ranges from
a ZVOL, thus optimizing disk space usage by allowing a ZVOL to
shrink instead of just grow.
We can't use zfs_space() or zfs_freesp() here, since these functions
only work on regular files, not volumes. Fortunately we can use the
low-level function dmu_free_long_range() which does exactly what we
want.
Currently the discard operation is not added to the log. That's not
a big deal since losing discard requests cannot result in data
corruption. It would however result in disk space usage higher than
it should be. Thus adding log support to zvol_discard() is probably
a good idea for a future improvement.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Currently only the (FALLOC_FL_PUNCH_HOLE) flag combination is
supported, since it's the only one that matches the behavior of
zfs_space(). This makes it pretty much useless in its current
form, but it's a start.
To support other flag combinations we would need to modify
zfs_space() to make it more flexible, or emulate the desired
functionality in zpl_fallocate().
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #334
The Linux block device queue subsystem exposes a number of configurable
settings described in Linux block/blk-settings.c. The defaults for these
settings are tuned for hard drives, and are not optimized for ZVOLs. Proper
configuration of these options would allow upper layers (I/O scheduler) to
take better decisions about write merging and ordering.
Detailed rationale:
- max_hw_sectors is set to unlimited (UINT_MAX). zvol_write() is able to
handle writes of any size, so there's no reason to impose a limit. Let the
upper layer decide.
- max_segments and max_segment_size are set to unlimited. zvol_write() will
copy the requests' contents into a dbuf anyway, so the number and size of
the segments are irrelevant. Let the upper layer decide.
- physical_block_size and io_opt are set to the ZVOL's block size. This
has the potential to somewhat alleviate issue #361 for ZVOLs, by warning
the upper layers that writes smaller than the volume's block size will be
slow.
- The NONROT flag is set to indicate this isn't a rotational device.
Although the backing zpool might be composed of rotational devices, the
resulting ZVOL often doesn't exhibit the same behavior due to the COW
mechanisms used by ZFS. Setting this flag will prevent upper layers from
making useless decisions (such as reordering writes) based on incorrect
assumptions about the behavior of the ZVOL.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
zvol_write() assumes that the write request must be written to stable storage
if rq_is_sync() is true. Unfortunately, this assumption is incorrect. Indeed,
"sync" does *not* mean what we think it means in the context of the Linux
block layer. This is well explained in linux/fs.h:
WRITE: A normal async write. Device will be plugged.
WRITE_SYNC: Synchronous write. Identical to WRITE, but passes down
the hint that someone will be waiting on this IO
shortly.
WRITE_FLUSH: Like WRITE_SYNC but with preceding cache flush.
WRITE_FUA: Like WRITE_SYNC but data is guaranteed to be on
non-volatile media on completion.
In other words, SYNC does not *mean* that the write must be on stable storage
on completion. It just means that someone is waiting on us to complete the
write request. Thus triggering a ZIL commit for each SYNC write request on a
ZVOL is unnecessary and harmful for performance. To make matters worse, ZVOL
users have no way to express that they actually want data to be written to
stable storage, which means the ZIL is broken for ZVOLs.
The request for stable storage is expressed by the FUA flag, so we must
commit the ZIL after the write if the FUA flag is set. In addition, we must
commit the ZIL before the write if the FLUSH flag is set.
Also, we must inform the block layer that we actually support FLUSH and FUA.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The second argument of sops->show_options() was changed from a
'struct vfsmount *' to a 'struct dentry *'. Add an autoconf check
to detect the API change and then conditionally define the expected
interface. In either case we are only interested in the zfs_sb_t.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#549
When the original build system code was added the release
component was accidentally omited from the development header
install path. This patch adds the missing path component so
it's always clear exactly what release your compiling against.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The Linux 3.1 kernel has introduced the concept of per-filesystem
shrinkers which are directly assoicated with a super block. Prior
to this change there was one shared global shrinker.
The zfs code relied on being able to call the global shrinker when
the arc_meta_limit was exceeded. This would cause the VFS to drop
references on a fraction of the dentries in the dcache. The ARC
could then safely reclaim the memory used by these entries and
honor the arc_meta_limit. Unfortunately, when per-filesystem
shrinkers were added the old interfaces were made unavailable.
This change adds support to use the new per-filesystem shrinker
interface so we can continue to honor the arc_meta_limit. The
major benefit of the new interface is that we can now target
only the zfs filesystem for dentry and inode pruning. Thus we
can minimize any impact on the caching of other filesystems.
In the context of making this change several other important
issues related to managing the ARC were addressed, they include:
* The dnlc_reduce_cache() function which was called by the ARC
to drop dentries for the Posix layer was replaced with a generic
zfs_prune_t callback. The ZPL layer now registers a callback to
drop these dentries removing a layering violation which dates
back to the Solaris code. This callback can also be used by
other ARC consumers such as Lustre.
arc_add_prune_callback()
arc_remove_prune_callback()
* The arc_reduce_dnlc_percent module option has been changed to
arc_meta_prune for clarity. The dnlc functions are specific to
Solaris's VFS and have already been largely eliminated already.
The replacement tunable now represents the number of bytes the
prune callback will request when invoked.
* Less aggressively invoke the prune callback. We used to call
this whenever we exceeded the arc_meta_limit however that's not
strictly correct since it results in over zeleous reclaim of
dentries and inodes. It is now only called once the arc_meta_limit
is exceeded and every effort has been made to evict other data from
the ARC cache.
* More promptly manage exceeding the arc_meta_limit. When reading
meta data in to the cache if a buffer was unable to be recycled
notify the arc_reclaim thread to invoke the required prune.
* Added arcstat_prune kstat which is incremented when the ARC
is forced to request that a consumer prune its cache. Remember
this will only occur when the ARC has no other choice. If it
can evict buffers safely without invoking the prune callback
it will.
* This change is also expected to resolve the unexpect collapses
of the ARC cache. This would occur because when exceeded just the
arc_meta_limit reclaim presure would be excerted on the arc_c
value via arc_shrink(). This effectively shrunk the entire cache
when really we just needed to reclaim meta data.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#466Closes#292
Directly changing inode->i_nlink is deprecated in Linux 3.2 by commit
SHA: bfe8684869601dacfcb2cd69ef8cfd9045f62170
Use the new set_nlink() kernel function instead.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes: #462
Added the necessary build infrastructure for building packages
compatible with the Arch Linux distribution. As such, one can now run:
$ ./configure
$ make pkg # Alternatively, one can run 'make arch' as well
on the Arch Linux machine to create two binary packages compatible with
the pacman package manager, one for the zfs userland utilities and
another for the zfs kernel modules. The new packages can then be
installed by running:
# pacman -U $package.pkg.tar.xz
In addition, source-only packages suitable for an Arch Linux chroot
environment or remote builder can also be build using the 'sarch' make
rule.
NOTE: Since the source dist tarball is created on the fly from the head
of the build tree, it's MD5 hash signature will be continually influx.
As a result, the md5sum variable was intentionally omitted from the
PKGBUILD files, and the '--skipinteg' makepkg option is used. This may
or may not have any serious security implications, as the source tarball
is not being downloaded from an outside source.
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#491
Update the code to use the bdi_setup_and_register() helper to
simplify the bdi integration code. The updated code now just
registers the bdi during mount and destroys it during unmount.
The only complication is that for 2.6.32 - 2.6.33 kernels the
helper wasn't available so in these cases the zfs code must
provide it. Luckily the bdi_setup_and_register() function
is trivial.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#367
For a long time now the kernel has been moving away from using the
pdflush daemon to write 'old' dirty pages to disk. The primary reason
for this is because the pdflush daemon is single threaded and can be
a limiting factor for performance. Since pdflush sequentially walks
the dirty inode list for each super block any delay in processing can
slow down dirty page writeback for all filesystems.
The replacement for pdflush is called bdi (backing device info). The
bdi system involves creating a per-filesystem control structure each
with its own private sets of queues to manage writeback. The advantage
is greater parallelism which improves performance and prevents a single
filesystem from slowing writeback to the others.
For a long time both systems co-existed in the kernel so it wasn't
strictly required to implement the bdi scheme. However, as of
Linux 2.6.36 kernels the pdflush functionality has been retired.
Since ZFS already bypasses the page cache for most I/O this is only
an issue for mmap(2) writes which must go through the page cache.
Even then adding this missing support for newer kernels was overlooked
because there are other mechanisms which can trigger writeback.
However, there is one critical case where not implementing the bdi
functionality can cause problems. If an application handles a page
fault it can enter the balance_dirty_pages() callpath. This will
result in the application hanging until the number of dirty pages in
the system drops below the dirty ratio.
Without a registered backing_device_info for the filesystem the
dirty pages will not get written out. Thus the application will hang.
As mentioned above this was less of an issue with older kernels because
pdflush would eventually write out the dirty pages.
This change adds a backing_device_info structure to the zfs_sb_t
which is already allocated per-super block. It is then registered
when the filesystem mounted and unregistered on unmount. It will
not be registered for mounted snapshots which are read-only. This
change will result in flush-<pool> thread being dynamically created
and destroyed per-mounted filesystem for writeback.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#174
Unlike most other Linux distributions archlinux installs its
init scripts in /etc/rc.d insead of /etc/init.d. This commit
provides an archlinux rc.d script for zfs and extends the
build infrastructure to ensure it get's installed in the
correct place.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#322
The .get_sb callback has been replaced by a .mount callback
in the file_system_type structure. When using the new
interface the caller must now use the mount_nodev() helper.
Unfortunately, the new interface no longer passes the vfsmount
down to the zfs layers. This poses a problem for the existing
implementation because we currently save this pointer in the
super block for latter use. It provides our only entry point
in to the namespace layer for manipulating certain mount options.
This needed to be done originally to allow commands like
'zfs set atime=off tank' to work properly. It also allowed me
to keep more of the original Solaris code unmodified. Under
Solaris there is a 1-to-1 mapping between a mount point and a
file system so this is a fairly natural thing to do. However,
under Linux they many be multiple entries in the namespace
which reference the same filesystem. Thus keeping a back
reference from the filesystem to the namespace is complicated.
Rather than introduce some ugly hack to get the vfsmount and
continue as before. I'm leveraging this API change to update
the ZFS code to do things in a more natural way for Linux.
This has the upside that is resolves the compatibility issue
for the long term and fixes several other minor bugs which
have been reported.
This commit updates the code to remove this vfsmount back
reference entirely. All modifications to filesystem mount
options are now passed in to the kernel via a '-o remount'.
This is the expected Linux mechanism and allows the namespace
to properly handle any options which apply to it before passing
them on to the file system itself.
Aside from fixing the compatibility issue, removing the
vfsmount has had the benefit of simplifying the code. This
change which fairly involved has turned out nicely.
Closes#246Closes#217Closes#187Closes#248Closes#231
The security_inode_init_security() function now takes an additional
qstr argument which must be passed in from the dentry if available.
Passing a NULL is safe when no qstr is available the relevant
security checks will just be skipped.
Closes#246Closes#217Closes#187
The inode eviction should unmap the pages associated with the inode.
These pages should also be flushed to disk to avoid the data loss.
Therefore, use truncate_setsize() in evict_inode() to release the
pagecache.
The API truncate_setsize() was added in 2.6.35 kernel. To ensure
compatibility with the old kernel, the patch defines its own
truncate_setsize function.
Signed-off-by: Prasad Joshi <pjoshi@stec-inc.com>
Closes#255
The WRITE_FLUSH, WRITE_FUA, and WRITE_FLUSH_FUA flags have been
introduced as a replacement for WRITE_BARRIER. This was done
to allow richer semantics to be expressed to the block layer.
It is the block layers responsibility to choose the correct way
to implement these semantics.
This change simply updates the bio's to use the new kernel API
which should be absolutely safe. However, since ZFS depends
entirely on this working as designed for correctness we do
want to be careful.
Closes#281
The previous commit 8a7e1ceefa wasn't
quite right. This check applies to both the user and kernel space
build and as such we must make sure it runs regardless of what
the --with-config option is set too.
For example, if --with-config=kernel then the autoconf test does
not run and we generate build warnings when compiling the kernel
packages.
Gcc versions 4.3.2 and earlier do not support the compiler flag
-Wno-unused-but-set-variable. This can lead to build failures
on older Linux platforms such as Debian Lenny. Since this is
an optional build argument this changes add a new autoconf check
for the option. If it is supported by the installed version of
gcc then it is used otherwise it is omited.
See commit's 12c1acde76 and
79713039a2 for the reason the
-Wno-unused-but-set-variable options was originally added.
How nfsd handles .fsync() has been changed a couple of times in the
recent kernels. But basically there are three cases we need to
consider.
Linux 2.6.12 - 2.6.33
* The .fsync() hook takes 3 arguments
* The nfsd will call .fsync() with a NULL file struct pointer.
Linux 2.6.34
* The .fsync() hook takes 3 arguments
* The nfsd no longer calls .fsync() but instead used sync_inode()
Linux 2.6.35 - 2.6.x
* The .fsync() hook takes 2 arguments
* The nfsd no longer calls .fsync() but instead used sync_inode()
For once it looks like we've gotten lucky. The first two cases can
actually be collased in to one if we stop using the file struct
pointer entirely. Since the dentry is still passed in both cases
this is possible. The last case can then be safely handled by
unconditionally using the dentry in the file struct pointer now
that we know the nfsd caller has been removed.
Closes#230
This change fixes a kernel panic which would occur when resizing
a dataset which was not open. The objset_t stored in the
zvol_state_t will be set to NULL when the block device is closed.
To avoid this issue we pass the correct objset_t as the third arg.
The code has also been updated to correctly notify the kernel
when the block device capacity changes. For 2.6.28 and newer
kernels the capacity change will be immediately detected. For
earlier kernels the capacity change will be detected when the
device is next opened. This is a known limitation of older
kernels.
Online ext3 resize test case passes on 2.6.28+ kernels:
$ dd if=/dev/zero of=/tmp/zvol bs=1M count=1 seek=1023
$ zpool create tank /tmp/zvol
$ zfs create -V 500M tank/zd0
$ mkfs.ext3 /dev/zd0
$ mkdir /mnt/zd0
$ mount /dev/zd0 /mnt/zd0
$ df -h /mnt/zd0
$ zfs set volsize=800M tank/zd0
$ resize2fs /dev/zd0
$ df -h /mnt/zd0
Original-patch-by: Fajar A. Nugraha <github@fajar.net>
Closes#68Closes#84
Added insert_inode_locked() helper function, prior to this most callers
used insert_inode_hash(). The older method doesn't check for collisions
in the inode_hashtable but it still acceptible for use. Fallback to
using insert_inode_hash() when insert_inode_locked() is unavailable.
The blk_queue_stackable() queue flag was added in 2.6.27 to handle dm
stacking drivers. Prior to this request stacking drivers were detected
by checking (q->request_fn == NULL), for earlier kernels we revert to
this legacy behavior.
To support automatically mounting your zfs on filesystem on boot
a basic init script is needed. Unfortunately, every distribution
has their own idea of the _right_ way to do things. Rather than
write one very complicated portable init script, which would be
invariably replaced by the distributions own anyway. I have
instead added support to provide multiple distribution specific
init scripts.
The correct init script for your distribution will be selected
by ZFS_AC_DEFAULT_PACKAGE which will set DEFAULT_INIT_SCRIPT.
During 'make install' the correct script for your system will
be installed from zfs/etc/init.d/zfs.DEFAULT_INIT_SCRIPT to the
usual /etc/init.d/zfs location.
Currently, there is zfs.fedora and a more generic zfs.lsb init
script. Hopefully, the distribution maintainers who know best
how they want their init scripts to function will feedback their
approved versions to be included in the project.
This change does not consider upstart jobs but I'm not at all
opposed to add that sort of thing.
With the removal of the minimal xvattr support from the spl this
support needs to be replaced in the zfs package. This is fairly
easily accomplished by directly adding portions of the sys/vnode.h
header from OpenSolaris. These xvattr additions have been placed
in the sys/xvattr.h header file and included as needed where simply
a sys/vnode.h was included before.
In additon to the xvattr types and helper macros two functions
were also included. The xva_init() and xva_getxoptattr() functions
were included as static inline functions in xvattr.h. They are
simple enough and it was simpler to place them here rather than
in their own .c file.
The open_bdev_exclusive() function has been replaced (again) by the
more generic blkdev_get_by_path() function. Additionally, the
counterpart function close_bdev_exclusive() has been replaced by
blkdev_put(). Because these functions are more generic versions
of the functions they replaced the compatibility macro must add
the FMODE_EXCL mask to ensure they are exclusive.
Closes#114
For legacy reasons the zvol.c and vdev_disk.c Linux compatibility
code ended up in sys/blkdev.h and sys/vdev_disk.h headers. While
there are worse places for this code to live it should be in a
linux/blkdev_compat.h header. This change moves this block device
Linux compatibility code in to the linux/blkdev_compat.h header
and updates all the correct #include locations. This is not a
functional change or bug fix, it is just code cleanup.
The new prefered inteface for evicting an inode from the inode cache
is the ->evict_inode() callback. It replaces both the ->delete_inode()
and ->clear_inode() callbacks which were previously used for this.
The xattr handler prototypes were sanitized with the idea being that
the same handlers could be used for multiple methods. The result of
this was the inode type was changes to a dentry, and both the get()
and set() hooks had a handler_flags argument added. The list()
callback was similiarly effected but no autoconf check was added
because we do not use the list() callback.
The fsync() callback in the file_operations structure used to take
3 arguments. The callback now only takes 2 arguments because the
dentry argument was determined to be unused by all consumers. To
handle this a compatibility prototype was added to ensure the right
prototype is used. Our implementation never used the dentry argument
either so it's just a matter of using the right prototype.
The const keyword was added to the 'struct xattr_handler' in the
generic Linux super_block structure. To handle this we define an
appropriate xattr_handler_t typedef which can be used. This was
the preferred solution because it keeps the code clean and readable.
Lay the initial ground work for a include/linux/ compatibility
directory. This was less critical in the past because the bulk
of the ZFS code consumes the Solaris API via the SPL. This API
was stable and the bulk Linux API differences were handled in
the SPL.
However, with the addition of a full Posix layer written directly
against the Linux APIs we are going to need more compatibility
code. It makes sense that all this code should be cleanly located
in one place. Subsequent patches should move the existing zvol
and vdev_disk compatibility code in to this directory.
