Fix zpl_revalidate() NULL deref

In zpl_revalidate() it's possible for the nameidata to be NULL
for kernels which still accept the parameter.  In particular,
lookup_one_len() calls d_revalidate() with a NULL nameidata.

Resolve the issue by checking for a NULL nameidata in which case
just set the flags to 0.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1226
fzap_cursor_move_to_key() should drop l_rwlock

Callers of zap_deref_leaf() must be careful to drop leaf->l_rwlock
since that function returns with the lock held on success.  All other
callers drop the lock correctly but it seems fzap_cursor_move_to_key()
does not.  This may block writers or cause VERIFY failures when the
lock is freed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1215
Closes zfsonlinux/spl#143
Closes zfsonlinux/spl#97
Add d_clear_d_op() compatibility

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
Fix test script error codes

The 'exit $?' command in the INT TERM EXIT trap was overwritting
the expected error code with the error code from mv.  Fix the
issue by removing the 'exit $?'.  It's important the we preserve
the original error code so failures are easily noticed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Fix zconfig.sh partitioning error

Parted version 3.0 doesn't allow us to specify the start and end
percentages as 50% and 100% respectively.  This results in:

  Error: The location 100% is outside the device /dev/zd0

Therefore we change the syntax to 51% and -1 for end of device.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
vdev_id: improve keyword parsing flexibility

The vdev_id udev helper strictly requires configuration file keywords
to always be anchored at the beginning of the line and to be followed
by a space character.  However, users may prefer to use indentation or
tab delimitation.  Improve flexibility by simply requiring a keyword
to be the first field on the line.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1239
Use dsl_dataset_snap_lookup()

Retire the dmu_snapshot_id() function which was introduced in the
initial .zfs control directory implementation.  There is already
an existing dsl_dataset_snap_lookup() which does exactly what we
need, and the dmu_snapshot_id() function as implemented is racy.

https://github.com/zfsonlinux/zfs/issues/1215#issuecomment-12579879

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1238
Avoid gcc -Werror=maybe-uninitialized warnings

Explicitly set acl details to zero to silence gcc (zfs_acl_node_read
can't be sure zfs_acl_znode_info will set acl_count and aclsize).
Normally suppressing these warnings by setting this to zero at
declaration time is a bad idea but in this instance it's hard to
avoid and should be fairly safe.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1244
Use strerror() not strerror_r()

The differ() function used strerror_r() instead of strerror() because
it allowed the error message to be directly copied in to a buffer.
This causes two issues under Linux.

* There are two versions of strerror_r() available an XSI-compliant
  version which returns an 'int' error code.  And a GNU-specific
  version which return a 'char *' to the resulting error string.

    int strerror_r(int errnum, char *buf, size_t buflen);   /* XSI */
    char *strerror_r(int errnum, char *buf, size_t buflen); /* GNU */

* The most recent versions of strerror_r() are annotated with the
  warn_unused_result attribute.  This causes the following warning
  since the upstream implementation casts the result to void.

    warning: ignoring return value of 'strerror_r', declared with
    attribute warn_unused_result [-Wunused-result]

The cleanest way to resolve both of these problems is just to use
strerror() and make a copy of the result in to the buffer.  This
resolves both issues and this is the only instance of strerror_r()
in the code base.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1231
Stop using /bin/ as a source in zconfig.sh

Test 5, 6, 7, and 7 in zconfig.sh use /bin/ as a source of random
directories and files for their test.  This has lead to unexpected
tests failures because the total size of /bin/ on the test system
isn't checked and it is entirely possible for it to be larger than
the target filesystem.

To resolve this issue we create a somewhat random collection of
files and directories in /var/tmp to use.  On average we expect
about 5MB of data with the worst case being 20MB.  This is large
enough to be interesting and small enough to always fit in the
default test datasets.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1113
Linux 2.6.26 compat, lookup_bdev()

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
Quiet mkfs.ext2 output

The -q option should quiet the mkfs.ext2 output but certain
versions of e2fsprogs appear to ignore it.  This can result in
an extra 'done' message in the test output.  To keep this noise
from distracting just direct stdout to /dev/null.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Illumos #3035 LZ4 compression support in ZFS and GRUB

3035 LZ4 compression support in ZFS and GRUB

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Christopher Siden <csiden@delphix.com>

References:
  illumos/illumos-gate@a6f561b4aee75d0d028e7b36b151c8ed8a86bc76
  https://www.illumos.org/issues/3035
  http://wiki.illumos.org/display/illumos/LZ4+Compression+In+ZFS

This patch has been slightly modified from the upstream Illumos
version to be compatible with Linux.  Due to the very limited
stack space in the kernel a lz4 workspace kmem cache is used.
Since we are using gcc we are also able to take advantage of the
gcc optimized __builtin_ctz functions.

Support for GRUB has been dropped from this patch.  That code
is available but those changes will need to made to the upstream
GRUB package.

Lastly, several hunks of dead code were dropped for clarity.  They
include the functions real_LZ4_uncompress(), LZ4_compressBound()
and the Visual Studio specific hunks wrapped in _MSC_VER.

Ported-by: Eric Dillmann <eric@jave.fr>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1217
Remove NPTL_GUARD_WITHIN_STACK

Commit 4b2f65b253952c5103311cc8bb4b8cdc6836fd7e increased the user
space stack by 4x to resolve certain stack overflows.  As such it
no longer makes sense to worry about a single extra page which
might or might not be part of the process stack.  There is now
ample headroom for normal usage.

By eliminating this configure check we are also resolving the
following segfault which intentionally occurs at configure time
and may be logged in dmesg.

  conftest[22156]: segfault at 7fbf18a47e48 ip 00000000004007fe
  sp 00007fbf18a4be50 error 6 in conftest[400000+1000]

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Retire zpool_id infrastructure

In the interest of maintaining only one udev helper to give vdevs
user friendly names, the zpool_id and zpool_layout infrastructure
is being retired.  They are superseded by vdev_id which incorporates
all the previous functionality.

Documentation for the new vdev_id(8) helper and its configuration
file, vdev_id.conf(5), can be found in their respective man pages.
Several useful example files are installed under /etc/zfs/.

  /etc/zfs/vdev_id.conf.alias.example
  /etc/zfs/vdev_id.conf.multipath.example
  /etc/zfs/vdev_id.conf.sas_direct.example
  /etc/zfs/vdev_id.conf.sas_switch.example

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #981
Illumos #3447 improve the comment in txg.c

3447 improve the comment in txg.c

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Reviewed by: Garrett D'Amore <garrett@damore.org>
Reviewed by: Richard Elling <richard.elling@dey-sys.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

References:
  illumos/illumos-gate@adbbcfface63b3a71922d5a25d34a2018c0435de
  https://www.illumos.org/issues/3447

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Fix rounding discrepancy in sa_find_sizes()

A rounding discrepancy exists between how sa_build_layouts() and
sa_find_sizes() calculate when the spill block needs to be kicked in.
This results in a narrow size range where sa_build_layouts() believes
there must be a spill block allocated but due to the discrepancy there
isn't.  A panic then occurs when the hdl->sa_spill NULL pointer is
dereferenced.

The following reproducer for this bug was isolated:

    truncate -s 128m /tmp/tank
    zpool create tank /tmp/tank
    zfs create -o xattr=sa tank/fish
    ln -s `perl -e 'print "z" x 41'` /tank/fish/z
    setfattr -hn trusted.foo -v`perl -e 'print "z"x45'` /tank/fish/z

This test results in roughly the following system attribute (SA)
layout:

  176 bytes - "standard" SA's
   41 bytes - name of symbolic link target
  100 bytes - XDR encoded nvlist for xattr
  ---
  317 bytes - total

Because 317 is less than DN_MAX_BONUSLEN (320), sa_find_sizes()
decides no spill block is needed. But sa_build_layouts() rounds 41 up
to 48 when computing the space requirements so it tries to switch to
the spill block.

Note that we were only able to reproduce this bug using a combination
of symbolic links and the Linux-specific xattr=sa dataset property.
So while this issue is not technically Linux-specific, it may be
difficult or impossible to hit the narrow size range needed to
reproduce it on other platforms.

To fix the discrepancy, round the running total in sa_find_sizes() up
to an 8-byte boundary before accounting for each SA, since this is how
they will be stored in the bonus and (possibly) spill buffers.

To make the intent of the code more clear, explicitly assert key
assumptions about expected alignment of data and whether spill-over
will occur.

Signed-off-by: Matthew Ahrens <mahrens@delphix.com
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1240
Fix mismatch between SA header size and layout

When a system attribute layout is created an inconsistency may occur
between the system attribute header (sa_hdr_phys_t) size and the
variable-sized attribute count stored in the layout.  The inconsistency
results in the following failed assertion when SA_HDR_SIZE_MATCH_LAYOUT
returns false:

SPLError: 11315:0:(sa.c:1541:sa_find_idx_tab())
ASSERTION((IS_SA_BONUSTYPE(bonustype) && SA_HDR_SIZE_MATCH_LAYOUT(hdr,
tb)) || !IS_SA_BONUSTYPE(bonustype) || (IS_SA_BONUSTYPE(bonustype) &&
hdr->sa_layout_info == 0)) failed

The bug originates in this snippet from sa_find_sizes().

    if (is_var_sz && var_size > 1) {
            if (P2ROUNDUP(hdrsize + sizeof (uint16_t),
                *total < full_space) {
                    hdrsize += sizeof (uint16_t);

This assumes that the current variable-sized attribute will be stored in
the current buffer and accounts for the space needed to store its size
in the sa_hdr_phys_t. However if the next attribute spills over we need
to store a blkptr_t at the end of the bonus buffer to point to the spill
block. If the current attribute is in the way of the blkptr_t then it
too will be relocated into the spill block. But since we've already
accounted for it in the header size we get the inconsistency described
above.

To avoid this, record the index of the last variable-sized attribute
that prompted a hdrsize increase, and reverse the increase if we later
determine that that attribute will be relocated to the spill block.

Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1250
Honor 80 character limit in 'zpool status'

This is a minor nit, but the second line of the 'action' message
when you need to upgrade your pool to support feature flags exceeds
the standard 80 character limit.  Fix it by moving the word
'feature' on to the third line.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Add zfs_disable_dup_eviction module option

Commit 1eb5bfa introduced a new zfs_disable_dup_eviction tunable.
It should have been made available as a module option in the
original patch but was overlooked.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>