NULL, but also can point to dead vnode, take that into account.
PR: kern/132068
Reported by: Edward Fisk" <7ogcg7g02@sneakemail.com>, kris
Fix based on patch from: Jaakko Heinonen <jh@saunalahti.fi>
MFC after: 1 week
commands executed by unprivileged users. Action is not really taken, but it is
logged to pool history, which might be confusing.
Reported by: Denis Ahrens <denis@h3q.com>
MFC after: 3 days
Such situation is not supported.
This problem was triggered by something like this:
# zpool create tank da0
# zfs snapshot tank@snap
# cd /tank/.zfs/snapshot/snap (this will mount the snapshot)
# cd
# mount -u nosuid /tank/.zfs/snapshot/snap (refcount leak)
# zpool export tank
cannot export 'tank': pool is busy
MFC after: 1 week
we will fail to unmount it, but it won't be removed from the tree,
so in that case there is no need to reinsert it.
This fixes a panic reproducable in the following steps:
# zfs create tank/foo
# zfs snapshot tank/foo@snap
# cd /tank/foo/.zfs/snapshot/snap
# umount /tank/foo
panic: avl_find() succeeded inside avl_add()
Reported by: trasz
MFC after: 3 days
provider is closed should be ok.
When administrator requests to change ZVOL size do it immediately if ZVOL
is closed or do it on last ZVOL close.
PR: kern/136942
Requested by: Bernard Buri <bsd@ask-us.at>
MFC after: 1 week
(..), calling readdir and looking for previous directory inode. In case of
.zfs/ directory this doesn't work, because .zfs/ is hidden by default, so it
won't be visible in readdir output.
Fix this by implementing VPTOCNP for snapshot directories, so __getcwd()
doesn't fail and getcwd() doesn't have to use readdir method.
This fixes /bin/pwd from within .zfs/snapshot/<name>/.
Suggested by: kib
Approved by: re (rwatson)
replace it with wrappers around our taskqueue(9).
To make it possible implement taskqueue_member() function which returns 1
if the given thread was created by the given taskqueue.
Approved by: re (kib)
initialized. Also destroy /dev/zfs before doing other deinitializations.
- Initialization through taskq is no longer needed and there is a race
where one of the zpool/zfs command loads zfs.ko and tries to do some work
immediately, but /dev/zfs is not there yet.
Reported by: pav
Approved by: re (kib)
panic when in zfs_fuid_create_cred() when userid is negative. It is
converted to unsigned value which makes IS_EPHEMERAL() macro to
incorrectly report that this is ephemeral ID. The most reasonable
solution for now is to always report that the given ID is not ephemeral.
PR: kern/132337
Submitted by: Matthew West <freebsd@r.zeeb.org>
Tested by: Thomas Backman <serenity@exscape.org>, Michael Reifenberger <mike@reifenberger.com>
Approved by: re (kib)
MFC after: 2 weeks
doesn't exist and user doesn't have write access to the file.
Without this fix, it returns bogus value instead of 0. For some
reason this didn't manifest on my kernel compiled with -O0.
PR: kern/136601
Submitted by: Jaakko Heinonen <jh at saunalahti dot fi>
Approved by: re (kib)
this change, ZFS uses SunOS Alternate Data Streams semantics - each
EA has its own permissions, which are set at EA creation time
and - unlike SunOS - invisible to the user and impossible to change.
From the user point of view, it's just broken: sometimes access
is granted when it shouldn't be, sometimes it's denied when
it shouldn't be.
This patch makes it behave just like UFS, i.e. depend on current
file permissions. Also, it fixes returned error codes (ENOATTR
instead of ENOENT) and makes listextattr(2) return 0 instead
of EPERM where there is no EA directory (i.e. the file never had
any EA).
Reviewed by: pjd (idea, not actual code)
Approved by: re (kib)
The programmer was aware that alignment was not guaranteed in the
packed structure and used bzero() to NULL out the pointers.
However, on ia64, the compiler is quite agressive in finding ILP
and calls to bzero() are often replaced by simple assignments (i.e.
stores). Especially when the width or size in question corresponds
with a store instruction (i.e. st1, st2, st4 or st8).
The problem here is not a compiler bug. The address of the memory
to zero-out was given by '&packed->nvl_priv' and given the type of
the 'packed' pointer the compiler could assume proper alignment for
the replacement of bzero() with an 8-byte wide store to be valid.
The problem is with the programmer. The programmer knew that the
address did not have the alignment guarantees needed for a regular
assignment, but failed to inform the compiler of that fact. In
fact, the programmer told the compiler the opposite: alignment is
guaranteed.
The fix is to avoid using a pointer of type "nvlist_t *" and
instead use a "char *" pointer as the basis for calculating the
address. This tells the compiler that only 1-byte alignment can
be assumed and the compiler will either keep the bzero() call
or instead replace it with a sequence of byte-wise stores. Both
are valid.
Approved by: re (kib)
vn_open_cred invocations shall not audit namei path.
In particular, specify VN_OPEN_NOAUDIT for dotdot lookup performed by
default implementation of vop_vptocnp, and for the open done for core
file. vn_fullpath is called from the audit code, and vn_open there need
to disable audit to avoid infinite recursion. Core file is created on
return to user mode, that, in particular, happens during syscall return.
The creation of the core file is audited by direct calls, and we do not
want to overwrite audit information for syscall.
Reported, reviewed and tested by: rwatson
by prefetched than helped. On i386 systems and systems with less than 4GB,
prefetch is now disabled by default. I've added a prefetch enable tunable, to
enable prefetching for those systems. The prefetch disable tunable will continue
to unconditionally disable prefetching.
- add FreeBSD implementation of xdrmem_control needed by zfs
- have zfs define xdr_ops using FreeBSD's definition
- remove solaris xdr files from zfs compile
adds probes for mutexes, reader/writer and shared/exclusive locks to
gather contention statistics and other locking information for
dtrace scripts, the lockstat(1M) command and other potential
consumers.
Reviewed by: attilio jhb jb
Approved by: gnn (mentor)
about removing a few #ifdefs and providing compatibility wrappers and
VOP implementations to get and set an ACL; ZFS does ACL enforcement all
by itself.
Note that the VOPs are ifdefed out for now, so this change should be
a no-op.
Reviewed by: pjd
the VFS. Now all the VFS_* functions and relating parts don't want the
context as long as it always refers to curthread.
In some points, in particular when dealing with VOPs and functions living
in the same namespace (eg. vflush) which still need to be converted,
pass curthread explicitly in order to retain the old behaviour.
Such loose ends will be fixed ASAP.
While here fix a bug: now, UFS_EXTATTR can be compiled alone without the
UFS_EXTATTR_AUTOSTART option.
VFS KPI is heavilly changed by this commit so thirdy parts modules needs
to be recompiled. Bump __FreeBSD_version in order to signal such
situation.
This is based on a fix that went in to opensolaris on March 9th. However, it uses a dedicated
thread instead of a Solaris' taskq to avoid doing a blocking memory allocation with the vnode
interlock held.
This fixes a long-time deadlock in ZFS. This is not, strictly speaking, an LOR. The spa_zio
thread releases a vnode, this calls in to vn_reclaim which in turn needs to acquire range locks
to sync dirty data out to disk. The range locks are already held by a user-level process waiting
on a condition variable that it the process is waiting on a spa_zio thread to signal it on. The
process could not be signalled because the spa_zio thread could not proceed.
The nature of this problem was not apparent due to ZFS locks opting out of witness which meant
that DDB did not know about the locks that were held by ZFS.
Reviewed by: pjd
MFC after: 7 days
the removal of NQNFS, but was left in in case it was required for NFSv4.
Since our new NFSv4 client and server can't use it for their
requirements, GC the old mechanism, as well as other unused lease-
related code and interfaces.
Due to its impact on kernel programming and binary interfaces, this
change should not be MFC'd.
Proposed by: jeff
Reviewed by: jeff
Discussed with: rmacklem, zach loafman @ isilon
directory for a znode. When the directory already exists, it returns a
referenced but unlocked vnode. When a directory does not yet exist, it
calls zfs_make_xattrdir() to create a new one. zfs_make_xattrdir() returns
the vnode both referenced and and locked and zfs_get_xattrdir() was leaking
this vnode lock to its callers. Fix this by dropping the vnode lock if
zfs_make_xattrdir() successfully creates a new extended attribute
directory.
Reviewed by: pjd
filesystem supports additional operations using shared vnode locks.
Currently this is used to enable shared locks for open() and close() of
read-only file descriptors.
- When an ISOPEN namei() request is performed with LOCKSHARED, use a
shared vnode lock for the leaf vnode only if the mount point has the
extended shared flag set.
- Set LOCKSHARED in vn_open_cred() for requests that specify O_RDONLY but
not O_CREAT.
- Use a shared vnode lock around VOP_CLOSE() if the file was opened with
O_RDONLY and the mountpoint has the extended shared flag set.
- Adjust md(4) to upgrade the vnode lock on the vnode it gets back from
vn_open() since it now may only have a shared vnode lock.
- Don't enable shared vnode locks on FIFO vnodes in ZFS and UFS since
FIFO's require exclusive vnode locks for their open() and close()
routines. (My recent MPSAFE patches for UDF and cd9660 already included
this change.)
- Enable extended shared operations on UFS, cd9660, and UDF.
Submitted by: ups
Reviewed by: pjd (ZFS bits)
MFC after: 1 month
Inside the kernel, the minor() function was responsible for obtaining
the device minor number of a character device. Because we made device
numbers dynamically allocated and independent of the unit number passed
to make_dev() a long time ago, it was actually a misnomer. If you really
want to obtain the device number, you should use dev2udev().
We already converted all the drivers to use dev2unit() to obtain the
device unit number, which is still used by a lot of drivers. I've
noticed not a single driver passes NULL to dev2unit(). Even if they
would, its behaviour would make little sense. This is why I've removed
the NULL check.
Ths commit removes minor(), minor2unit() and unit2minor() from the
kernel. Because there was a naming collision with uminor(), we can
rename umajor() and uminor() back to major() and minor(). This means
that the makedev(3) manual page also applies to kernel space code now.
I suspect umajor() and uminor() isn't used that often in external code,
but to make it easier for other parties to port their code, I've
increased __FreeBSD_version to 800062.
This bring huge amount of changes, I'll enumerate only user-visible changes:
- Delegated Administration
Allows regular users to perform ZFS operations, like file system
creation, snapshot creation, etc.
- L2ARC
Level 2 cache for ZFS - allows to use additional disks for cache.
Huge performance improvements mostly for random read of mostly
static content.
- slog
Allow to use additional disks for ZFS Intent Log to speed up
operations like fsync(2).
- vfs.zfs.super_owner
Allows regular users to perform privileged operations on files stored
on ZFS file systems owned by him. Very careful with this one.
- chflags(2)
Not all the flags are supported. This still needs work.
- ZFSBoot
Support to boot off of ZFS pool. Not finished, AFAIK.
Submitted by: dfr
- Snapshot properties
- New failure modes
Before if write requested failed, system paniced. Now one
can select from one of three failure modes:
- panic - panic on write error
- wait - wait for disk to reappear
- continue - serve read requests if possible, block write requests
- Refquota, refreservation properties
Just quota and reservation properties, but don't count space consumed
by children file systems, clones and snapshots.
- Sparse volumes
ZVOLs that don't reserve space in the pool.
- External attributes
Compatible with extattr(2).
- NFSv4-ACLs
Not sure about the status, might not be complete yet.
Submitted by: trasz
- Creation-time properties
- Regression tests for zpool(8) command.
Obtained from: OpenSolaris
from one parent directory to another, in addition to the usual access checks
one also needs write access to the subdirectory being moved.
Approved by: rwatson (mentor), pjd
to add more V* constants, and the variables changed by this patch were often
being assigned to mode_t variables, which is 16 bit.
Approved by: rwatson (mentor)
In particular following functions KPI results modified:
- bufobj_invalbuf()
- bufsync()
and BO_SYNC() "virtual method" of the buffer objects set.
Main consumers of bufobj functions are affected by this change too and,
in particular, functions which changed their KPI are:
- vinvalbuf()
- g_vfs_close()
Due to the KPI breakage, __FreeBSD_version will be bumped in a later
commit.
As a side note, please consider just temporary the 'curthread' argument
passing to VOP_SYNC() (in bufsync()) as it will be axed out ASAP
Reviewed by: kib
Tested by: Giovanni Trematerra <giovanni dot trematerra at gmail dot com>
that DTrace uses.
This fixes a bug that would have affected kernels built with MAC and all
kernels built after the mpsafetty integration.
The bug will be apparent in RELENG7 on MAC kernels.
Reported by: kan
After I removed all the unit2minor()/minor2unit() calls from the kernel
yesterday, I realised calling minor() everywhere is quite confusing.
Character devices now only have the ability to store a unit number, not
a minor number. Remove the confusion by using dev2unit() everywhere.
This commit could also be considered as a bug fix. A lot of drivers call
minor(), while they should actually be calling dev2unit(). In -CURRENT
this isn't a problem, but it turns out we never had any problem reports
related to that issue in the past. I suspect not many people connect
more than 256 pieces of the same hardware.
Reviewed by: kib
- The vnode has to be locked exclusively before calling insmntque().
- Until I find a way to handle insmntque() failures use VV_FORCEINSMQ flag
to force insmntque() to always succeed.
Reported by: kris, trasz, des, others
Suggested by: kib
Tested by: trasz
we free memory from underneath them.
This fixes an occasional panic I've been seeing in softclock() where a bad
pointer would be encountered when pushing DTrace hard.
Now that we got rid of the minor-to-unit conversion and the constraints
on device minor numbers, we can convert the functions that operate on
minor and unit numbers to simple macro's. The unit2minor() and
minor2unit() macro's are now no-ops.
The ZFS code als defined a macro named `minor'. Change the ZFS code to
use umajor() and uminor() here, as it is the correct approach to do
this. Also add $FreeBSD$ to keep SVN happy.
Approved by: philip (mentor), pjd
Except for the case where we use the cloner library (clone_create() and
friends), there is no reason to enforce a unique device minor number
policy. There are various drivers in the source tree that allocate unr
pools and such to provide minor numbers, without using them themselves.
Because we still need to support unique device minor numbers for the
cloner library, introduce a new flag called D_NEEDMINOR. All cdevsw's
that are used in combination with the cloner library should be marked
with this flag to make the cloning work.
This means drivers can now freely use si_drv0 to store their own flags
and state, making it effectively the same as si_drv1 and si_drv2. We
still keep the minor() and dev2unit() routines around to make drivers
happy.
The NTFS code also used the minor number in its hash table. We should
not do this anymore. If the si_drv0 field would be changed, it would no
longer end up in the same list.
Approved by: philip (mentor)
(Don't ask for a vendor import of this yet, we're in the early days of svn)
Instead of using cyclic timers to call the state clean and deadman callbacks,
use a callout on FreeBSD to avoid the deadlock on FreeBSD due to trying to
send interprocessor interrupts with interrupts disabled.
Reported by: ps, jhb, peter, thompsa
filesystem-specific vnode data to the struct vnode. Provide the
default implementation for the vop_advlock and vop_advlockasync.
Purge the locks on the vnode reclaim by using the lf_purgelocks().
The default implementation is augmented for the nfs and smbfs.
In the nfs_advlock, push the Giant inside the nfs_dolock.
Before the change, the vop_advlock and vop_advlockasync have taken the
unlocked vnode and dereferenced the fs-private inode data, racing with
with the vnode reclamation due to forced unmount. Now, the vop_getattr
under the shared vnode lock is used to obtain the inode size, and
later, in the lf_advlockasync, after locking the vnode interlock, the
VI_DOOMED flag is checked to prevent an operation on the doomed vnode.
The implementation of the lf_purgelocks() is submitted by dfr.
Reported by: kris
Tested by: kris, pho
Discussed with: jeff, dfr
MFC after: 2 weeks
user-mode lock manager, build a kernel with the NFSLOCKD option and
add '-k' to 'rpc_lockd_flags' in rc.conf.
Highlights include:
* Thread-safe kernel RPC client - many threads can use the same RPC
client handle safely with replies being de-multiplexed at the socket
upcall (typically driven directly by the NIC interrupt) and handed
off to whichever thread matches the reply. For UDP sockets, many RPC
clients can share the same socket. This allows the use of a single
privileged UDP port number to talk to an arbitrary number of remote
hosts.
* Single-threaded kernel RPC server. Adding support for multi-threaded
server would be relatively straightforward and would follow
approximately the Solaris KPI. A single thread should be sufficient
for the NLM since it should rarely block in normal operation.
* Kernel mode NLM server supporting cancel requests and granted
callbacks. I've tested the NLM server reasonably extensively - it
passes both my own tests and the NFS Connectathon locking tests
running on Solaris, Mac OS X and Ubuntu Linux.
* Userland NLM client supported. While the NLM server doesn't have
support for the local NFS client's locking needs, it does have to
field async replies and granted callbacks from remote NLMs that the
local client has contacted. We relay these replies to the userland
rpc.lockd over a local domain RPC socket.
* Robust deadlock detection for the local lock manager. In particular
it will detect deadlocks caused by a lock request that covers more
than one blocking request. As required by the NLM protocol, all
deadlock detection happens synchronously - a user is guaranteed that
if a lock request isn't rejected immediately, the lock will
eventually be granted. The old system allowed for a 'deferred
deadlock' condition where a blocked lock request could wake up and
find that some other deadlock-causing lock owner had beaten them to
the lock.
* Since both local and remote locks are managed by the same kernel
locking code, local and remote processes can safely use file locks
for mutual exclusion. Local processes have no fairness advantage
compared to remote processes when contending to lock a region that
has just been unlocked - the local lock manager enforces a strict
first-come first-served model for both local and remote lockers.
Sponsored by: Isilon Systems
PR: 95247 107555 115524 116679
MFC after: 2 weeks
after each SYSINIT() macro invocation. This makes a number of
lightweight C parsers much happier with the FreeBSD kernel
source, including cflow's prcc and lxr.
MFC after: 1 month
Discussed with: imp, rink
always curthread.
As KPI gets broken by this patch, manpages and __FreeBSD_version will be
updated by further commits.
Tested by: Andrea Barberio <insomniac at slackware dot it>
namespace in order to handle lockmgr fields in a controlled way instead
than spreading all around bogus stubs:
- VN_LOCK_AREC() allows lock recursion for a specified vnode
- VN_LOCK_ASHARE() allows lock sharing for a specified vnode
In FFS land:
- BUF_AREC() allows lock recursion for a specified buffer lock
- BUF_NOREC() disallows recursion for a specified buffer lock
Side note: union_subr.c::unionfs_node_update() is the only other function
directly handling lockmgr fields. As this is not simple to fix, it has
been left behind as "sole" exception.
conjuction with 'thread' argument passing which is always curthread.
Remove the unuseful extra-argument and pass explicitly curthread to lower
layer functions, when necessary.
KPI results broken by this change, which should affect several ports, so
version bumping and manpage update will be further committed.
Tested by: kris, pho, Diego Sardina <siarodx at gmail dot com>
Remove this argument and pass curthread directly to underlying
VOP_LOCK1() VFS method. This modify makes the code cleaner and in
particular remove an annoying dependence helping next lockmgr() cleanup.
KPI results, obviously, changed.
Manpage and FreeBSD_version will be updated through further commits.
As a side note, would be valuable to say that next commits will address
a similar cleanup about VFS methods, in particular vop_lock1 and
vop_unlock.
Tested by: Diego Sardina <siarodx at gmail dot com>,
Andrea Di Pasquale <whyx dot it at gmail dot com>
(BIO_WRITE and BIO_FLUSH) as it is done is Solaris. The difference is
that Solaris calls it only for sync requests, but we can't say in GEOM
is the request is sync or async, so we do it for every request.
MFC after: 1 week
to kproc_xxx as they actually make whole processes.
Thos makes way for us to add REAL kthread_create() and friends
that actually make theads. it turns out that most of these
calls actually end up being moved back to the thread version
when it's added. but we need to make this cosmetic change first.
I'd LOVE to do this rename in 7.0 so that we can eventually MFC the
new kthread_xxx() calls.
value, so we don't run out of KVA. The default vnodes limit fits better for
UFS, but ZFS allocated more file system specific memory for a vnode than UFS.
Don't touch vnodes limit if we detect it was tuned by system administrator
and restore original value when ZFS is unloaded.
This isn't final fix, but before we implement something better, this will
help to stabilize ZFS under heavy load on i386.
Approved by: re (bmah)
implementing some of them using existing ones.
- Allow to compile ZFS on all archs and use atomic operations surrounded
by global mutex on archs we don't have or can't have all atomic
operations needed by ZFS.
1. Pass locking flags to VFS_ROOT().
2. Check v_mountedhere while the vnode is locked.
3. Always return locked vnode on success.
Change 1 fixes problem reported by Stephen M. Rumble - after
zfs_vfsops.c,1.9 change, zfs_root() no longer locks the vnode
unconditionally and traverse() didn't pass right lock type to
VFS_ROOT(). The result was that kernel paniced when .zfs/ directory
was accessed via NFS.
based on individual fields beeing set. This doesn't work for setattr replay,
because va_type is set there, so we add AT_TYPE flag to va_mask, which won't
be accepted by zfs_setattr().
Reported by: kris
initialization is complete. This fixes some root-on-ZFS
configurations.
Reported by: Bruno Damour <freebsd.ruomad@free.fr>
Tested by: Bruno Damour <freebsd.ruomad@free.fr>
and show up with different names: first try to open provider using
remembered name and compare its ident, if equal, this is our provider,
if not equal or there is no provider with such name, find provider with
remembered ident and don't care about the name.
non-mapped data as possible at once and not page-by-page. Which this change we
combain I/Os, but also saves many VM_OBJECT_UNLOCK()/VM_OBJECT_LOCK()
operations.
Simple 'fsx -l 33554432 -o 524288 -N 10000 /tank/fsx' test shows ~23%
performance increase.
- vm_page_undirty() is enough (instead of vm_page_set_validclean()), but it has
to be called before we write the data in case someone makes page dirty after
our write, but before our vm_page_undirty() call.
- Always dmu_write, not matter if uiomove() succeeded, because it could
partially be ok and we would lose some changes.
All good ideas from: ups
in all other file system on FreeBSD (instead from inactive() method).
A nice side-effect of this change, except that it speedups file system
when mmaped file are often open/closed, is that it makes FreeBSD's
namecache work:)
This fixes slow operations on mmaped files, because without this fix,
pages were written to disk multiple times.
If one is looking for even greater speed up for such operation, he should
disable ZIL (by setting vfs.zfs.zil_disable to 1 in /boot/loader.conf).
Disabling ZIL makes fsx run ~9 times faster.
o Fix linewrap issues.
o Fix two typos (s/Recomended/Recommended/ and s/tunning/tuning/)
o Remove a couple of extra instances of the word "of".
o Update names of kmem_size variables.
Approved by: pjd
- Move FreeBSD-specific code to zfs_freebsd_*() functions in zfs_vnops.c
and keep original functions as similar to vendor's code as possible.
- Add various includes back, now that we have them.
macro, as za_first_integer field also contains type. This should be fixed in
ZFS itself, but this bug is not visible on Solaris, because there, type is
not stored in za_first_integer. On the other hand it will be visible on
MacOS X.
Reported by: Barry Pederson <bp@barryp.org>
@118370 Correct typo.
@118371 Integrate changes from vendor.
@118491 Show backtrace on unexpected code paths.
@118494 Integrate changes from vendor.
@118504 Fix sendfile(2). I had two ways of fixing it:
1. Fixing sendfile(2) itself to use VOP_GETPAGES() instead of
hacking around with vn_rdwr(UIO_NOCOPY), which was suggested
by ups.
2. Modify ZFS behaviour to handle this special case.
Although 1 is more correct, I've choosen 2, because hack from 1
have a side-effect of beeing faster - it reads ahead MAXBSIZE
bytes instead of reading page by page. This is not easy to implement
with VOP_GETPAGES(), at least not for me in this very moment.
Reported by: Andrey V. Elsukov <bu7cher@yandex.ru>
@118525 Reorganize the code to reduce diff.
@118526 This code path is expected. It is simply when file is opened with
O_FSYNC flag.
Reported by: kris
Reported by: Michal Suszko <dry@dry.pl>
unload instead of returning EBUSY. This check tells if there are mounted
ZFS file systems or not. We can't unload if there are mounted file systems.
Reported by: Andrey V. Elsukov <bu7cher@yandex.ru>
- Reduce default number of spa_zio_* threads to N*spa_zio_issue
plus N*spa_zio_intr threads per ZIO type, where N is the number
of CPUs.
- Put ZIO type number in thread's name.
than 2GB of RAM. This was because our physmem is long and 'physmem*PAGESIZE'
can be negative for more than 2GB of memory.
Reported by: Andrey V. Elsukov <bu7cher@yandex.ru>
It is not yet tested by Andrey, so there can be other problems, but this
was definiately a bug, so I'm committing a fix now.
- Tune number of namecache entires better (based on desiredvnodes).
- Handle vfs_lowvnodes event by releasing requested number of name cache
entries, but no less than 5%.
Reported by: simokawa
- Allow to shrink ARC down to 16MB (instead of 64MB).
- Set arc_max to 1/2 of kmem_map by default.
- Start freeing things earlier when low memory situation is detected.
- Serialize execution of arc_lowmem().
I decided to setup minimum ZFS memory requirements to 512MB of RAM and 256MB of
kmem_map size. If there is less RAM or kmem_map, a warning will be printed.
World is cruel, be no better. In other words: modern file system requires
modern hardware:)
From ZFS administration guide:
"Currently the minimum amount of memory recommended to install a Solaris
system is 512 Mbytes. However, for good ZFS performance, at least one
Gbyte or more of memory is recommended."
