To lay the ground work for introducing the taskq_dispatch_prealloc()
interface, the tq_work_list and tq_threads fields had to be replaced
with new alternatives in the taskq_t structure.
The tq_threads field was replaced with tq_thread_list. Rather than
storing the pointers to the taskq's kernel threads in an array, they are
now stored as a list. In addition to laying the ground work for the
taskq_dispatch_prealloc() interface, this change could also enable taskq
threads to be dynamically created and destroyed as threads can now be
added and removed to this list relatively easily.
The tq_work_list field was replaced with tq_active_list. Instead of
keeping a list of taskq_ent_t's which are currently being serviced, a
list of taskq_threads currently servicing a taskq_ent_t is kept. This
frees up the taskq_ent_t's tqent_list field when it is being serviced
(i.e. now when a taskq_ent_t is being serviced, it's tqent_list field
will be empty).
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #65
The spl_task structure was renamed to taskq_ent, and all of
its fields were renamed to have a prefix of 'tqent' rather
than 't'. This was to align with the naming convention which
the ZFS code assumes. Previously these fields were private
so the name never mattered.
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #65
This change adds the neglected SPLAT_TEST_FINI call for the
SPLAT_TASKQ_TEST6_ID, just as is done for the other 5 SPLAT_TASKQ_*
tests.
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#64
The splat_taskq_test4_common function was incorrectly referencing
the splat_taskq-test13_func symbol, when it meant to be using the
splat_taskq_test4_func symbol.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#61
This is a bit of cleanup I'd been meaning to get to for a while
to reduce the chance of a type conflict. Well that conflict
finally occurred with the kstat_init() function which conflicts
with a function in the 2.6.32-6-pve kernel.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#56
As of Linux 3.1 the shrink_dcache_memory and shrink_icache_memory
functions have been removed. This same task is now accomplished
more cleanly with per super block shrinkers. This unfortunately
leaves us no easy way to support the dnlc_reduce_cache() function.
This support has always been entirely optional. So when no
reasonable interface is available allow the dnlc_reduce_cache()
function to effectively become a no-op.
The downside of this change is that it will prevent the zfs arc
meta data limts from being enforced. However, the current zfs
implementation in this regard is already flawed and needs to
be reworked. If the arc needs to enfore a meta data limit it
will need to be extended to coordinate directly with the zpl.
This will allow us to drop all this compatibility code and get
more fine grained control over the cache management.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #52
Prior to Linux 3.1 the kern_path_parent symbol was exported for
use by kernel modules. As of Linux 3.1 it is now longer easily
available. To handle this case the spl will now dynamically
look up address of the missing symbol at module load time.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #52
Be careful not to unconditionally clear the PF_MEMALLOC bit in
the task structure. It may have already been set when entering
kv_alloc() in which case it must remain set on exit. In
particular the kswapd thread will have PF_MEMALLOC set in
order to prevent it from entering direct reclaim. By clearing
it we allow the following NULL deref to potentially occur.
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8109c7ab>] balance_pgdat+0x25b/0x4ff
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes ZFS issue #287
This would cause problems when using 'zfs send' with a file as the
target (rather than a pipe or a socket as is usually the case) as
for each write the destination offset in the file would be 0.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes ZFS issue #391
The typo did not have any effect (apart from a negligible performance
impact) because skc->skc_flags * KMC_OFFSLAB is always non-null when
at least one bit in skc->skc_flags is set.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
In a non-debug build the ASSERT() would be optimized away
which could cause pending work items to not be cancelled.
We must also use cancel_delayed_work_sync() rather than just
cancel_delayed_work() to actually wait until work items have
completed. Otherwise they might accidentally access free'd
memory.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes ZFS bugs #279, #62, #363, #418
File descriptors are a per-process resource. The same descriptor
in different processes can refer to different files. find_file()
incorrectly assumed that file descriptors are globally unique.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes ZFS issue #386
No longer print the following warning to the console when the
/etc/hostid file is missing. This is the expected default behavior.
Keeping the hostid in sync with the initramfs is now accomplished
by creating the /etc/hostid in the initramfs not on the system.
SPL: The /etc/hostid file is not found.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
When running 'make install' without DESTDIR set the module install
rules would mistakenly destroy the 'modules.*' files for ALL of
your installed kernels. This could lead to a non-functional system
for the alternate kernels because 'depmod -a' will only be run for
the kernel which was compiled against. This issue would not impact
anyone using the 'make <deb|rpm|pkg>' build targets to build and
install packages.
The fix for this issue is to only remove extraneous build products
when DESTDIR is set. This almost exclusively indicates we are
building packages and installed the build products in to a temporary
staging location. Additionally, limit the removal the unneeded
build products to the target kernel version.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#328
Deprecate the /usr/bin/hostid call by reading the /etc/hostid file
directly. Add the spl_hostid_path parameter to override the default
/etc/hostid path.
Rename the set_hostid() function to hostid_exec() to better reflect
actual behavior and complement the new hostid_read() function.
Use HW_INVALID_HOSTID as the spl_hostid sentinel value because
zero seems to be a valid gethostid() result on Linux.
While the splat tests were originally designed to stress test
the Solaris primatives. I am extending them to include some kernel
compatibility tests. Certain linux APIs have changed frequently.
These tests ensure that added compatibility is working properly
and no unnoticed regression have slipped in.
Test 1 and 2 add basic regression tests for shrink_icache_memory
and shrink_dcache_memory. These are simply functional tests to
ensure we can call these functions safely. Checking for correct
behavior is more difficult since other running processes will
influence the behavior. However, these functions are provided
by the kernel so if we can successfully call them we assume they
are working correctly.
Test 3 checks that shrinker functions are being registered and
called correctly. As of Linux 3.0 the shrinker API has changed
four different times so I felt the need to add a trivial test
case to ensure each variant works as expected.
Update the the wrapper macros for the memory shrinker to handle
this 4th API change. The callback function now takes a
shrink_control structure. This is certainly a step in the
right direction but it's annoying to have to accomidate yet
another version of the API.
It has become necessary to be able to optionally disable
direct memory reclaim for certain taskqs. To support
this the TASKQ_NORECLAIM flags has been added which sets
the PF_MEMALLOC bit for all threads in the taskq.
Change the SPL kernel messages for module loading and module
unloading so that they are similar to the ZFS kernel messages.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This reverts commit 1814251453.
Demote the gawk call back to awk and ensure that stderr is attached. GNU gawk
tolerates a missing stderr handle, but many utilities do not, which could be
why a regular awk call was unexplainably failing on some systems.
Use argv[0] instead of sh_path for consistency internally and with other Linux
drivers.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Provide a call_usermodehelper() alternative by letting the hostid be passed as
a module parameter like this:
$ modprobe spl spl_hostid=0x12345678
Internally change the spl_hostid variable to unsigned long because that is the
type that the coreutils /usr/bin/hostid returns.
Move the hostid command into GET_HOSTID_CMD for consistency with the similar
GET_KALLSYMS_ADDR_CMD invocation.
Use argv[0] instead of sh_path for consistency internally and with other Linux
drivers.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The function zlib_deflate_workspacesize() now take 2 arguments.
This was done to avoid always having to allocate the maximum size
workspace (268K). The caller can now specific the windowBits and
memLevel compression parameters to get a smaller workspace.
For our purposes we introduce a spl_zlib_deflate_workspacesize()
wrapper which accepts both arguments. When the two argument
version of zlib_deflate_workspacesize() is available the arguments
are passed through. When it's not we assume the worst case and
a maximally sized workspace is used.
The path_lookup() function has been renamed to kern_path_parent()
and the flags argument has been removed. The only behavior now
offered is that of LOOKUP_PARENT. The spl already always passed
this flag so dropping the flag does not impact us.
This is a long over due compatibility change. Way, way, way back
in 2007 there was a push to remove all consumers of SPIN_LOCK_UNLOCKED.
Finally, in 2011 with 2.6.39 all the consumers have been updated
and SPIN_LOCK_UNLOCKED was removed. It's about time we use the
new API as well, this change does exactly that. DEFINE_SPINLOCK()
was available as far back as 2.6.12 so there doesn't need to be
any additional autoconf-foo for this change.
Flagged by the default -Wunused-but-set-variable gcc option when
running under Fedora 15. Since it's correct this variable is
entirely unused this commit removes it.
To resolve a potiential filesystem corruption issue a second
argument was added to invalidate_inodes(). This argument controls
whether dirty inodes are dropped or treated as busy when invalidating
a super block. When only the legacy API is available the second
argument will be dropped for compatibility.
Provide the dnlc_reduce_cache() function which attempts to prune
cached entries from the dcache and icache. After the entries are
pruned any slabs which they may have been using are reaped.
Note the API takes a reclaim percentage but we don't have easy
access to the total number of cache entries to calculate the
reclaim count. However, in practice this doesn't need to be
exactly correct. We simply need to reclaim some useful fraction
(but not all) of the cache. The caller can determine if more
needs to be done.
One of the most common things you want to know when looking at
the slab is how much memory is being used. This information was
available in /proc/spl/kmem/slab but only on a per-slab basis.
This commit adds the following /proc/sys/kernel/spl/kmem/slab*
entries to make total slab usage easily available at a glance.
slab_kmem_total - Total kmem slab size
slab_kmem_avail - Alloc'd kmem slab size
slab_kmem_max - Max observed kmem slab size
slab_vmem_total - Total vmem slab size
slab_vmem_avail - Alloc'd vmem slab size
slab_vmem_max - Max observed vmem slab size
NOTE: The slab_*_max values are expected to over report because
they show maximum values since boot, not current values.
The 'slab_fail', 'slab_create', and 'slab_destroy' columns in the slab
output have been removed because they are virtually always zero and
not very useful.
The much more useful 'size' and 'alloc' columns have been added which
show the total slab size and how much of the total size has been
allocated to objects.
Finally, the formatting has been updated to be much more human
readable while still being friendly for tool like awk to parse.
The Linux shrinker has gone through three API changes since 2.6.22.
Rather than force every caller to understand all three APIs this
change consolidates the compatibility code in to the mm-compat.h
header. The caller then can then use a single spl provided
shrinker API which does the right thing for your kernel.
SPL_SHRINKER_CALLBACK_PROTO(shrinker_callback, cb, nr_to_scan, gfp_mask);
SPL_SHRINKER_DECLARE(shrinker_struct, shrinker_callback, seeks);
spl_register_shrinker(&shrinker_struct);
spl_unregister_shrinker(&&shrinker_struct);
spl_exec_shrinker(&shrinker_struct, nr_to_scan, gfp_mask);
Solaris credentials don't have an fsuid/fsguid field but Linux
credentials do. To handle this case the Solaris API is being
modestly extended to include the crgetfsuid()/crgetfsgid()
helper functions.
Addititionally, because the crget*() helpers are implemented
identically regardless of HAVE_CRED_STRUCT they have been
moved outside the #ifdef to common code. This simplification
means we only have one version of the helper to keep to to date.
As part of vmalloc() a __pte_alloc_kernel() allocation may occur. This
internal allocation does not honor the gfp flags passed to vmalloc().
This means even when vmalloc(GFP_NOFS) is called it is possible that a
synchronous reclaim will occur. This reclaim can trigger file IO which
can result in a deadlock. This issue can be avoided by explicitly
setting PF_MEMALLOC on the process to subvert synchronous reclaim when
vmalloc() is called with !__GFP_FS.
An example stack of the deadlock can be found here (1), along with the
upstream kernel bug (2), and the original bug discussion on the
linux-mm mailing list (3). This code can be properly autoconf'ed
when the upstream bug is fixed.
1) http://github.com/behlendorf/zfs/issues/labels/Vmalloc#issue/133
2) http://bugzilla.kernel.org/show_bug.cgi?id=30702
3) http://marc.info/?l=linux-mm&m=128942194520631&w=4
The xvattr support in the spl has always simply consisted of
defining a couple structures and a few #defines. This was enough
to enable compilation of code which just passed xvattr types
around but not enough to effectively manipulate them.
This change removes even this minimal support leaving it up
to packages which leverage the spl to prove the full xvattr
support. By removing it from the spl we ensure not conflict
with the higher level packages.
This just leaves minimal vnode support for basical manipulation
of files. This code is does have the proper support functions
in the spl and a set of regression tests.
Additionally, this change removed the unused 'caller_context_t *'
type and replaces it with a 'void *'.
A zlib regression test has been added to verify the correct behavior
of z_compress_level() and z_uncompress. The test case simply takes
a 128k buffer, it compresses the buffer, it them uncompresses the
buffer, and finally it compares the buffers after the transform.
If the buffers match then everything is fine and no data was lost.
It performs this test for all 9 zlib compression levels.
While portions of the code needed to support z_compress_level() and
z_uncompress() where in place. In reality the current implementation
was non-functional, it just was compilable.
The critical missing component was to setup a workspace for the
compress/uncompress stream structures to use. A kmem_cache was
added for the workspace area because we require a large chunk
of memory. This avoids to need to continually alloc/free this
memory and vmap() the pages which is very slow. Several objects
will reside in the per-cpu kmem_cache making them quick to acquire
and release. A further optimization would be to adjust the
implementation to additional ensure the memory is local to the cpu.
Currently that may not be the case.
In the 2.6.37 kernel the function invalidate_inodes() is no longer
exported for use by modules. This memory management functionality
is needed to invalidate the inodes attached to a super block without
unmounting the filesystem.
Because this function still exists in the kernel and the prototype
is available is a common header all we strictly need is the symbol
address. The address is obtained using spl_kallsyms_lookup_name()
and assigned to the variable invalidate_inodes_fn. Then a #define
is used to replace all instances of invalidate_inodes() with a
call to the acquired address. All the complexity is hidden behind
HAVE_INVALIDATE_INODES and invalidate_inodes() can be used as usual.
Long term we should try to get this, or another, interface made
available to modules again.
Previously we would ASSERT in cv_destroy() if it was ever called
with active waiters. However, I've now seen several instances in
OpenSolaris code where they do the following:
cv_broadcast();
cv_destroy();
This leaves no time for active waiters to be woken up and scheduled
and we trip the ASSERT. This has not been observed to be an issue
on OpenSolaris because their cv_destroy() basically does nothing.
They still do run the risk of the memory being free'd after the
cv_destroy() and hitting a bad paging request. But in practice
this race is so small and unlikely it either doesn't happen, or
is so unlikely when it does happen the root cause has not yet been
identified.
Rather than risk the same issue in our code this change updates
cv_destroy() to block until all waiters have been woken and
scheduled. This may take some time because each waiter must
acquire the mutex.
This change may have an impact on performance for frequently
created and destroyed condition variables. That however is a price
worth paying it avoid crashing your system. If performance issues
are observed they can be addressed by the caller.
Previously these were defined to noops but rather than give
the misleading impression that these are actually implemented
I'm removing the type entirely for clarity.
Both of these caches were previously allowed to be either a
vmem or kmem cache based on the size of the object involved.
Since we know the object won't be to large and performce is
much better for a kmem cache for them to be kmem backed.
The cv_timedwait() function by definition must wait unconditionally
for cv_signal()/cv_broadcast() before waking. This causes processes
to go in the D state which increases the load average. The load
average is the summation of processes in D state and run queue.
To avoid this it can be desirable to sleep interruptibly. These
processes do not count against the load average but may be woken by
a signal. It is up to the caller to determine why the process
was woken it may be for one of three reasons.
1) cv_signal()/cv_broadcast()
2) the timeout expired
3) a signal was received
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Create spl_inode_lock/spl_inode_unlock compability macros to simply
access to the inode mutex/sem. This avoids the need to have to ugly
up the code with the required #define's at every call site. At the
moment the SPL only uses this in one place but higher layers can
benefit from the macro.
To validate the correct behavior of the TSD interfaces it's
important that we add a regression test. This test is designed
to minimally exercise the fundamental TSD behavior, it does not
attempt to validate all potential corner cases.
The test will first create 32 keys via tsd_create() and register
a common destructor. Next 16 wait threads will be created each
of which set/verify a random value for all 32 keys, then block
waiting to be released by the control thread. Meanwhile the
control thread verifies that none of the destructors have been
run prematurely.
The next phase of the test is to create 16 exit threads which
set/verify a random value for all 32 keys. They then immediately
exit. This is is designed to verify tsd_exit() which will be
called via thread_exit(). This must result in all registered
destructors being run and the memory for the tsd being free'd.
After this tsd_destroy() is verified by destroying all 32 keys.
Once again we must see the expected number of destructors run
and the tsd memory free'd. At this point the blocked threads
are released and they exit calling tsd_exit() which should do
very little since all the tsd has already been destroyed.
If this all goes off without a hitch the test passes. To ensure
no memory has been leaked, I have manually verified that after
spl module unload no memory is reported leaked.
Thread specific data has implemented using a hash table, this avoids
the need to add a member to the task structure and allows maximum
portability between kernels. This implementation has been optimized
to keep the tsd_set() and tsd_get() times as small as possible.
The majority of the entries in the hash table are for specific tsd
entries. These entries are hashed by the product of their key and
pid because by design the key and pid are guaranteed to be unique.
Their product also has the desirable properly that it will be uniformly
distributed over the hash bins providing neither the pid nor key is zero.
Under linux the zero pid is always the init process and thus won't be
used, and this implementation is careful to never to assign a zero key.
By default the hash table is sized to 512 bins which is expected to
be sufficient for light to moderate usage of thread specific data.
The hash table contains two additional type of entries. They first
type is entry is called a 'key' entry and it is added to the hash during
tsd_create(). It is used to store the address of the destructor function
and it is used as an anchor point. All tsd entries which use the same
key will be linked to this entry. This is used during tsd_destory() to
quickly call the destructor function for all tsd associated with the key.
The 'key' entry may be looked up with tsd_hash_search() by passing the
key you wish to lookup and DTOR_PID constant as the pid.
The second type of entry is called a 'pid' entry and it is added to the
hash the first time a process set a key. The 'pid' entry is also used
as an anchor and all tsd for the process will be linked to it. This
list is using during tsd_exit() to ensure all registered destructors
are run for the process. The 'pid' entry may be looked up with
tsd_hash_search() by passing the PID_KEY constant as the key, and
the process pid. Note that tsd_exit() is called by thread_exit()
so if your using the Solaris thread API you should not need to call
tsd_exit() directly.
For debugging purposes the condition varaibles keep track of the
mutex used during a wait. The idea is to validate that all callers
always use the same mutex. Unfortunately, we have seen cases where
the caller reuses the condition variable with a different mutex but
in a way which is known to be safe. My reading of the man pages
suggests you should not do this and always cv_destroy()/cv_init()
a new mutex. However, there is overhead in doing this and it does
appear to be allowed under Solaris.
To accomidate this behavior cv_wait_common() and __cv_timedwait()
have been modified to clear the associated mutex when the last
waiter is dropped. This ensures that while the condition variable
is in use the incorrect mutex case is detected. It also allows the
condition variable to be safely recycled without requiring the
overhead of a cv_destroy()/cv_init() as long as it isn't currently
in use.
Finally, spin lock cv->cv_lock was removed because it is not required.
When the condition variable is used properly the caller will always
be holding the mutex so the spin lock is redundant. The lock was
originally added because I expected to need to protect more than
just the cv->cv_mutex. It turns out that was not the case.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
As of linux-2.6.36 the last in-tree consumer of fops->ioctl() has
been removed and thus fops()->ioctl() has also been removed. The
replacement hook is fops->unlocked_ioctl() which has existed in
kernel since 2.6.12. Since the SPL only contains support back
to 2.6.18 vintage kernels, I'm not adding an autoconf check for
this and simply moving everything to use fops->unlocked_ioctl().
In the linux-2.6.36 kernel the fs_struct lock was changed from a
rwlock_t to a spinlock_t. If the kernel would export the set_fs_pwd()
symbol by default this would not have caused us any issues, but they
don't. So we're forced to add a new autoconf check which sets the
HAVE_FS_STRUCT_SPINLOCK define when a spinlock_t is used. We can
then correctly use either spin_lock or write_lock in our custom
set_fs_pwd() implementation.
Prakash Surya
Brian Behlendorf
Gunnar Beutner
Darik Horn
Neependra Khare