Switch KM_SLEEP to KM_PUSHPAGE

Prevent snapshot_check to initiate I/O during memory allocation.

Signed-off-by: Massimo Maggi <massimo@mmmm.it>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1023
zfs.8: add missing info about dedup, mlslabel

These sections were missing from the `zfs.8` man page.  Add them.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1026
txg is spelled as tgx in places

Term 'transaction group' is commonly abbreviated as txg in ZFS sources.
There are some places (Linux specific MODULE_PARAM_DESC() macros)
where it is incorrectly spelled as 'tgx'.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1030
Make zfs_immediate_write_sz a module paramater

zfs_immediate_write_sz variable is a tunable, but lacks proper
module_param() instrumentation.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1032
Fix zfs_write_limit_max integer size mismatch on 32-bit systems

Commit c409e4647f221ab724a0bd10c480ac95447203c3 introduced a
number of module parameters.  This required several types to be
changed to accomidate the required module parameters Linux macros.

Unfortunately, arc.c contained its own extern definition of the
zfs_write_limit_max variable and its type was not updated to be
consistent with its dsl_pool.c counterpart.  If the variable had
been properly marked extern in a common header, then gcc would
have generated a warning and this would not have slipped through.

The result of this was that the ARC unconditionally expected
zfs_write_limit_max to be 64-bit. Unfortunately, the largest size
integer module parameter that Linux supports is unsigned long, which
varies in size depending on the host system's native word size. The
effect was that on 32-bit systems, ARC incorrectly performed 64-bit
operations on a 32-bit value by reading the neighboring 32 bits as
the upper 32 bits of the 64-bit value.

We correct that by changing the extern declaration to use the unsigned
long type and move these extern definitions in to the common arc.h
header. This should make ARC correctly treat zfs_write_limit_max as a
32-bit value on 32-bit systems.

Reported-by: Jorgen Lundman <lundman@lundman.net>
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #749
Fix zfs_txg_timeout module parameter

Allow the zfs_txg_timeout variable to be dynamically tuned at run
time.  By pulling it down out of the variable declaration it will
be evaluted each time through the loop.

The zfs_txg_timeout variable is now declared extern in a the common
sys/txg.h header rather than locally in dsl_scan.c.  This prevents
potential type mismatches if the global variable needs to be used
elsewhere.

Move the module_param() code in to the same source file where
zfs_txg_timeout is declared.  This is the most logical location.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Remove vmem_size() consumers

There are currently three vmem_size() consumers all of which are
part of the ARC implemention.  However, since the expected behavior
of the Linux and Solaris virtual memory subsystems are so different
the behavior in each of these instances needs to be reevaluated.

* arc_evict_needed() - This is actually dead code.  Arena support
was never added to the SPL and zio_arena is always NULL.  This
support isn't needed so we simply remove this dead code.

* arc_memory_throttle() - On Solaris where virtual memory constitutes
almost all of the address space we can reasonably expect there to be
a fairly large amount free.  However, on Linux by default we only
have about 100MB total and that's heavily used by the ARC.  So the
expectation on Linux is that this will usually be a small value.
Therefore we remove the vmem_size() check for i386 systems because
the expectation is that it will be less than the zfs_write_limit_max.

* arc_init() - Here vmem_size() is used to initially size the ARC.
Since the ARC is currently backed by the virtual address space it
makes sense to use this as a limit on the ARC for 32-bit systems.
This code can be removed when the ARC is backed by the page cache.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #831
Don't ashift-align vdev read requests.

Currently, the size of read and write requests on vdevs is aligned
according to the vdev's ashift, allocating a new ZIO buffer and padding
if need be.

This makes sense for write requests to prevent read/modify/write if the
write happens to be smaller than the device's internal block size.

For reads however, the rationale is less clear. It seems that the
original code aligns reads because, on Solaris, device drivers will
outright refuse unaligned requests.

We don't have that issue on Linux. Indeed, Linux block devices are able
to accept requests of any size, and take care of alignment issues
themselves.

As a result, there's no point in enforcing alignment for read requests
on Linux. This is a nice optimization opportunity for two reasons:
- We remove a memory allocation in a heavily-used code path;
- The request gets aligned in the lowest layer possible, which shrinks
  the path that the additional, useless padding data has to travel.
  For example, when using 4k-sector drives that lie about their sector
  size, using 512b read requests instead of 4k means that there will
  be less data traveling down the ATA/SCSI interface, even though the
  drive actually reads 4k from the platter.

The only exception is raidz, because raidz needs to read the whole
allocated block for parity.

This patch removes alignment enforcement for read requests, except on
raidz. Note that we also remove an assertion that checks that we're
aligning a top-level vdev I/O, because that's not the case anymore for
repair writes that results from failed reads.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1022
Linux 3.6 compat, sops->write_super() removed

The .write_super callback was removed the the super_operations
structure by Linux commit f0cd2dbb6cf387c11f87265462e370bb5469299e.
All file systems are now expected to self manage writing any dirty
state assoicated with their super block.

ZFS never made use of this callback so it can simply be removed
from the super_operations structure.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #873
Linux 3.6 compat, sget()

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
Linux 3.6 compat, iops->lookup()

As of Linux commit 00cd8dd3bf95f2cc8435b4cac01d9995635c6d0b the
struct nameidata is no longer passed to iops->lookup.  Instead
only the inamedata->flags are passed.

ZFS like almost all Linux fileystems never made use of this so
only the prototype needs to be wrapped for compatibility.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #873
Linux 3.6 compat, iops->create()

As of Linux commit ebfc3b49a7ac25920cb5be5445f602e51d2ea559 the
struct nameidata is no longer passed to iops->create.  Instead
only the result of (inamedata->flags & LOOKUP_EXCL) is passed.

ZFS like almost all Linux fileystems never made use of this so
only the prototype needs to be wrapped for compatibility.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #873
Linux 3.6 compat, iops->mkdir()

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
Merge branch 'linux-3.6'

This branch adds the required compatibility code to support the
Linux 3.6 kernel.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #873
Disable ztest deadman timer

The ztest deadman timer has been causing false positives in the
testing VMs.  To make it easier to spot possible regressions
I'm disabling this timer.  The buildbot test infrastructure
will still mark ztest instances which take to long to complete
as failures.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1018
Return positive error number in zfsctl_shares_lookup.

Otherwise it will cause zpl_shares_lookup() to return a invalid
pointer when an error occurs.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Closes #626 #885 #947 #977
Limit zfs_vdev_aggregation_limit to SPA_MAXBLOCKSIZE

Prevent users from setting the zfs_vdev_aggregation_limit tuning
larger than SPA_MAXBLOCKSIZE.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #520
Switch KM_SLEEP to KM_PUSHPAGE

In this particular instance the allocation occurred in the context
of sys_msync()->...->zpl_putpage() where we must be careful not to
initiate additional I/O.

Signed-off-by: Massimo Maggi <massimo@mmmm.it>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1038
Do not return /dev/loop-control in unused_loop_device

The function unused_loop_device in /usr/libexec/zfs/common.sh
returns /dev/loop-control on the first call. This device is NOT
a loop device (https://github.com/torvalds/linux/commit/770fe30)
it is a control device. This in turn causes the script zconfig.sh
to fail with:

  zpool-create.sh: Error 1 creating /tmp/zpool-vdev0 ->
  /dev/loop-control loopback

The patch makes the function return /dev/loop[0-9]* which are
loop devices.

Signed-off-by: Andrew Reid <ColdCanuck@nailedtotheperch.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #797
Condition variable usage, zevent_cv

The following incorrect usage of cv_broadcast() was caught by
code inspection.  The cv_broadcast() function must be called
under the associated mutex to preventing racing with cv_wait().

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