Illumos 5049 - panic when removing log device

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Mattew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Saso Kiselkov <skiselkov@gmail.com>
Approved by: Rich Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/5049
  https://github.com/illumos/illumos-gate/commit/2986efa

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2636
Fragmentation should display as '-' if spacemap_histogram=disabled

When com.delphix:spacemap_histogram is disabled, the value of
fragmentation was printing as 18446744073709551615 (UINT64_MAX),
when it should print as '-'.

The issue was caused by a small mistake during the merge of
"4980 metaslabs should have a fragmentation metric."

upstream: https://github.com/illumos/illumos-gate/commit/2e4c998
ZoL: https://github.com/zfsonlinux/zfs/commit/f3a7f66

The problem is in zpool_get_prop_literal, where the handling of the
pool property ZPOOL_PROP_FRAGMENTATION was added to wrong the
section. In particular, ZPOOL_PROP_FRAGMENTATION should not be in
the section where zpool_get_state(zhp) == POOL_STATE_UNAVAIL, but
lower down after it's already been determined that the pool is in
fact available, which is where upstream illumos correctly has had
it.

Thanks to lundman for helping to track down this bug.

Signed-off-by: Jorgen Lundman <lundman@lundman.net>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2664
Linux AIO Support

nfsd uses do_readv_writev() to implement fops->read and fops->write.
do_readv_writev() will attempt to read/write using fops->aio_read and
fops->aio_write, but it will fallback to fops->read and fops->write when
AIO is not available. However, the fallback will perform a call for each
individual data page. Since our default recordsize is 128KB, sequential
operations on NFS will generate 32 DMU transactions where only 1
transaction was needed. That was unnecessary overhead and we implement
fops->aio_read and fops->aio_write to eliminate it.

ZFS originated in OpenSolaris, where the AIO API is entirely implemented
in userland's libc by intelligently mapping them to VOP_WRITE, VOP_READ
and VOP_FSYNC.  Linux implements AIO inside the kernel itself. Linux
filesystems therefore must implement their own AIO logic and nearly all
of them implement fops->aio_write synchronously. Consequently, they do
not implement aio_fsync(). However, since the ZPL works by mapping
Linux's VFS calls to the functions implementing Illumos' VFS operations,
we instead implement AIO in the kernel by mapping the operations to the
VOP_READ, VOP_WRITE and VOP_FSYNC equivalents. We therefore implement
fops->aio_fsync.

One might be inclined to make our fops->aio_write implementation
synchronous to make software that expects this behavior safe. However,
there are several reasons not to do this:

1. Other platforms do not implement aio_write() synchronously and since
the majority of userland software using AIO should be cross platform,
expectations of synchronous behavior should not be a problem.

2. We would hurt the performance of programs that use POSIX interfaces
properly while simultaneously encouraging the creation of more
non-compliant software.

3. The broader community concluded that userland software should be
patched to properly use POSIX interfaces instead of implementing hacks
in filesystems to cater to broken software. This concept is best
described as the O_PONIES debate.

4. Making an asynchronous write synchronous is non sequitur.

Any software dependent on synchronous aio_write behavior will suffer
data loss on ZFSOnLinux in a kernel panic / system failure of at most
zfs_txg_timeout seconds, which by default is 5 seconds. This seems like
a reasonable consequence of using non-compliant software.

It should be noted that this is also a problem in the kernel itself
where nfsd does not pass O_SYNC on files opened with it and instead
relies on a open()/write()/close() to enforce synchronous behavior when
the flush is only guarenteed on last close.

Exporting any filesystem that does not implement AIO via NFS risks data
loss in the event of a kernel panic / system failure when something else
is also accessing the file. Exporting any file system that implements
AIO the way this patch does bears similar risk. However, it seems
reasonable to forgo crippling our AIO implementation in favor of
developing patches to fix this problem in Linux's nfsd for the reasons
stated earlier. In the interim, the risk will remain. Failing to
implement AIO will not change the problem that nfsd created, so there is
no reason for nfsd's mistake to block our implementation of AIO.

It also should be noted that `aio_cancel()` will always return
`AIO_NOTCANCELED` under this implementation. It is possible to implement
aio_cancel by deferring work to taskqs and use `kiocb_set_cancel_fn()`
to set a callback function for cancelling work sent to taskqs, but the
simpler approach is allowed by the specification:

```
Which operations are cancelable is implementation-defined.
```

http://pubs.opengroup.org/onlinepubs/009695399/functions/aio_cancel.html

The only programs on my system that are capable of using `aio_cancel()`
are QEMU, beecrypt and fio use it according to a recursive grep of my
system's `/usr/src/debug`. That suggests that `aio_cancel()` users are
rare. Implementing aio_cancel() is left to a future date when it is
clear that there are consumers that benefit from its implementation to
justify the work.

Lastly, it is important to know that handling of the iovec updates differs
between Illumos and Linux in the implementation of read/write. On Linux,
it is the VFS' responsibility whle on Illumos, it is the filesystem's
responsibility.  We take the intermediate solution of copying the iovec
so that the ZFS code can update it like on Solaris while leaving the
originals alone. This imposes some overhead. We could always revisit
this should profiling show that the allocations are a problem.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #223
Closes #2373
Add object type checking to zap_lockdir()

If a non-ZAP object is passed to zap_lockdir() it will be treated
as a valid ZAP object.  This can result in zap_lockdir() attempting
to read what it believes are leaf blocks from invalid disk locations.
The SCSI layer will eventually generate errors for these bogus IOs
but the caller will hang in zap_get_leaf_byblk().

The good news is that is a situation which can not occur unless the
pool has been damaged.  The bad news is that there are reports from
both FreeBSD and Solaris of damaged pools.  Specifically, there are
normal files in the filesystem which reference another normal file
as their parent.

Since pools like this are known to exist the zap_lockdir() function
has been updated to verify the type of the object.  If a non-ZAP
object has been passed it EINVAL will be returned immediately.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2597
Issue #2602
Illumos 5117 - spacemap reallocation can cause corruption

5117 space map reallocation can cause corruption
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/projects/illumos-gate/issues/5117
  https://github.com/illumos/illumos-gate/commit/e503a68

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2662
Implement fallocate FALLOC_FL_PUNCH_HOLE

Add support for the FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE mode of
fallocate(2).  Mimic the behavior of other native file systems such as
ext4 in cases where the file might be extended. If the offset is beyond
the end of the file, return success without changing the file. If the
extent of the punched hole would extend the file, only the existing tail
of the file is punched.

Add the zfs_zero_partial_page() function, modeled after update_page(),
to handle zeroing partial pages in a hole-punching operation.  It must
be used under a range lock for the requested region in order that the
ARC and page cache stay in sync.

Move the existing page cache truncation via truncate_setsize() into
zfs_freesp() for better source structure compatibility with upstream code.

Add page cache truncation to zfs_freesp() and zfs_free_range() to handle
hole punching.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #2619
Document the "readonly" pool property

This documentation is based FreeBSD's zpool(8) man page.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2682
Fix z_teardown_inactive_lock deadlock

When rolling back a mounted filesystem zfs_suspend() is called
which acquires the z_teardown_inactive_lock.  This lock can not
be dropped until the filesystem has been rolled back and resumed
in zfs_resume_fs().

Therefore, we must not call iput() under this lock because it
may result in the inode->evict() handler being called which also
takes this lock.  Instead use zfs_iput_async() to ensure dropping
the last reference is deferred and runs in a safe context.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2670
Document environment variables for zdb, zfs, zinject and zpool.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2691
Illumos 5140 - message about "%recv could not be opened" is printed when booting after crash

Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Max Grossman <max.grossman@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>

References:
  https://www.illumos.org/projects/illumos-gate//issues/5140
  https://github.com/illumos/illumos-gate/commit/2243853

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2676
Remove reverse indentation from zed comments.

Remove all occurrences of reverse indentation from zed comments for
consistency within the project code base.

Signed-off-by: Chris Dunlap <cdunlap@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2695
Remove obsolete comment about guard pages

Remove an obsolete comment that refers to code removed by commit
79c6e4c4. The code and comment related to space consumed by guard
pages in user-space stacks, which we no longer take into account.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2722
Illumos 5174 - add sdt probe for blocked read in dbuf_read()

5174 add sdt probe for blocked read in dbuf_read()
Reviewed by: Basil Crow <basil.crow@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Reviewed by: Boris Protopopov <bprotopopov@hotmail.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Reviewed by: Garrett D'Amore <garrett@damore.org>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  https://www.illumos.org/issues/5174
  https://github.com/illumos/illumos-gate/commit/f6164ad

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2710
Illumos 5177 - remove dead code from dsl_scan.c

5177 remove dead code from dsl_scan.c
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  https://www.illumos.org/issues/5177
  https://github.com/illumos/illumos-gate/commit/5f37736

Porting notes:

The local variable 'buf' was removed from dsl_scan_visitbp().
This wasn't part of the original patch but it should have been.

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2712
Illumos 5161 - add tunable for number of metaslabs per vdev

5161 add tunable for number of metaslabs per vdev
Reviewed by: Alex Reece <alex.reece@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/5161
  https://github.com/illumos/illumos-gate/commit/bf3e216

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2698
Illumos 5147 - zpool list -v should show individual disk capacity

The 'zpool list -v' command displays lots of info but excludes the
capacity of each disk. This should be added.

5147 zpool list -v should show individual disk capacity
Reviewed by: Adam Leventhal <adam.leventhal@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Matthew Ahrens <matthew.ahrens@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>

References:
  https://www.illumos.org/issues/5147
  https://github.com/illumos/illumos-gate/commit/7a09f97

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2688
Properly NULL terminate string in zfs_strcmp_pathname

The utility cppcheck caught this.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2330
Fix function call with uninitialized value in vdev_inuse

LLVM's static analyzer reported that we could pass an uninitialized
pool_guid to spa_by_guid() in vdev_inuse(). Upon review, it is correct.
An attempt to repurpose a spare or L2ARC drive from an exported pool
will cause the pool_guid passed to spa_by_guid() to be unintialized
information from the stack. This will cause non-deterministic behavior.
Since there is no reason why we cannot repurpose such disks, we modify
vdev_inuse() to avoid calling spa_by_guid() when they are detected.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2330
lib/libzpool/kernel.c: Assert no owners in rw_destroy()

This is intended to cause ztest to fail when rw_destroy() is called on a
rwlock that has owners.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2330
Illumos 5139 - SEEK_HOLE failed to report a hole at end of file

5139 SEEK_HOLE failed to report a hole at end of file
Reviewed by: Adam Leventhal <adam.leventhal@delphix.com>
Reviewed by: Alex Reece <alex.reece@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Max Grossman <max.grossman@delphix.com>
Reviewed by: Peng Dai <peng.dai@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>

References:
  https://www.illumos.org/issues/5139
  https://github.com/illumos/illumos-gate/commit/0fbc0cd

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2714