We cannot busy a page before doing pagefaults.
Infact, it can deadlock against vnode lock, as it tries to vget().
Other functions, right now, have an opposite lock ordering, like
vm_object_sync(), which acquires the vnode lock first and then
sleeps on the busy mechanism.
Before this patch is reinserted we need to break this ordering.
Sponsored by: EMC / Isilon storage division
Reported by: kib
- It does not let pages respect the LRU policy
- It bloats the active/inactive queues of few pages
Try to avoid it as much as possible with the long-term target to
completely remove it.
Use the soft-busy mechanism to protect page content accesses during
short-term operations (like uiomove_fromphys()).
After this change only vm_fault_quick_hold_pages() is still using the
hold mechanism for page content access.
There is an additional complexity there as the quick path cannot
immediately access the page object to busy the page and the slow path
cannot however busy more than one page a time (to avoid deadlocks).
Fixing such primitive can bring to complete removal of the page hold
mechanism.
Sponsored by: EMC / Isilon storage division
Discussed with: alc
Reviewed by: jeff
Tested by: pho
Skip eviction step of processing free records when doing ZFS
receive to avoid the expensive search operation of non-existent
dbufs in dn_dbufs.
Illumos ZFS issues:
3834 incremental replication of 'holey' file systems is slow
MFC after: 2 weeks
To quote Illumos issue #3888:
When 'zfs recv -F' is used with an incremental recv it rolls
back any changes made since the last snapshot in case new
changes were made to the file system while the recv is in
progress (without -F the recv would fail when it does it's
final check to commit the recv-ed data as the recv-ed data
conflicts with the newly written data).
However, if there is a snapshot taken after the recv began
rolling back to the 'latest' snapshot will not help and the
recv will still fail. 'zfs recv -F' should be extended to
destroy any snapshots created since the source snapshot when
finishing the recv (effectively rolling back through all
snapshots, instead of just to the latest snapshot).
Illumos ZFS issues:
3888 zfs recv -F should destroy any snapshots created since the
incremental source
MFC after: 2 weeks
To quote Illumos #3875:
The problem here is that if we ever end up in the error
path, we drop the locks protecting access to the zfsvfs_t
prior to forcibly unmounting the filesystem. Because z_os
is NULL, any thread that had already picked up the zfsvfs_t
and was sitting in ZFS_ENTER() when we dropped our locks
in zfs_resume_fs() will now acquire the lock, attempt to
use z_os, and panic.
Illumos ZFS issues:
3875 panic in zfs_root() after failed rollback
MFC after: 2 weeks
existed before IOCTL code refactoring merged change 4445fffb from illumos
at r248571.
This change allows `zpool clear` to be used again to recover suspended pool.
It seems the only was supposed by the code to restore pool operation after
reconnecting lost disks that were required for data completeness. There
are still cases where `zpool clear` command can just safely stuck due to
deadlocks inside ZFS kernel part, but probably that is better then having
no chances to recover at all.
- move init and fini code into separate functions (like it is done upstream)
- invoke fini code via shutdown_post_sync event hook
This should make zfs close its underlying devices during shutdown,
which may be important for their drivers.
MFC after: 20 days
All other places where a znode is allocated do not need z_vnode at all.
These are:
- zfs_create_share_dir
- zfs_create_fs
This chnage ensures two things:
- VN_LOCK_ASHARE is not erroneously called for VFIFO vnodes
- vn_lock is called on a fully constructed vnode with correct v_ops
The change also allows to make zfs_znode_cache_constructor a normal
kmem_cache constructor again (as it is in upstream).
This allows to avoid a problem where zfs_znode_cache_destructor
may be called on un-constructed znodes.
MFC after: 17 days
Unconditionally freeing a page is not good, especially if it is the page
that was wired by the caller. The checks are picked up from
kern_sendfile.
MFC after: 3 weeks
Quoting illumos issue #3836:
Currently zio_free() always puts the zio on a list for subsequent
processing by zio_free_sync(). This is only necessary for frees that
might need to issue reads (gang and dedup blocks).
By processing the majority of the frees as we encounter them, we reduce
the amount of time that the spa_sync() thread spends burning CPU and
not doing any i/o, thus increasing the overall write throughput of the
system.
Illumos ZFS issues:
3836 zio_free() can be processed immediately in the common case
MFC after: 1 week
I missed to register zfs_ioc_jail and zfs_ioc_unjail as legacy ioctl's
with the new zfs_ioctl_register_legacy() function.
These operations do not modify pools or datasets so there is no need to
log them to pool history.
Reported by: Alexander Leidinger <ale@FreeBSD.org> and others on current@
MFC after: 3 days
This could happen if a thread doing a page-in loses a ZFS range lock
race to a thread writing to the same range
This fixes "panic: vm_page_alloc: pindex already allocated" in
http://docs.FreeBSD.org/cgi/mid.cgi?1372165971.96049.42.camel
Submitted by: avg
MFC after: 1 week
Restore a previous behavior before r251646, where when destructing
ZFS snapshot, the ioctl would return ENOENT when it hit any of
them in the errlist (the new behavior was only return ENOENT when
all returns error).
Illumos ZFS issues:
3829 fix for 3740 changed behavior of zfs destroy/hold/release ioctl
MFC after: 1 week
ZFS event processing should work on R/O root filesystems
Illumos ZFS issues:
3749 zfs event processing should work on R/O root filesystems
MFC after: 2 weeks
* Illumos ZFS issue #3805 arc shouldn't cache freed blocks
Quote from the Illumos issue:
ZFS should proactively evict freed blocks from the cache.
Even though these freed blocks will never be used again, and thus
will eventually be evicted, this causes us to use memory
inefficiently for 2 reasons:
1. A block that is freed has no chance of being accessed again, but
will be kept in memory preferentially to a block that was accessed
before it (and is thus older) but has not been freed and thus has
at least some chance of being accessed again.
2. We partition the ARC into several buckets:
user data that has been accessed only once (MRU)
metadata that has been accessed only once (MRU)
user data that has been accessed more than once (MFU)
metadata that has been accessed more than once (MFU)
The user data vs metadata split is somewhat arbitrary, and the
primary control on how much memory is used to cache data vs metadata
is to simply try to keep the proportion the same as it has been in the
past (each bucket "evicts against" itself). The secondary control is
to evict data before evicting metadata.
Because of this bucketing, we may end up with one bucket mostly
containing freed blocks that are very old, while another bucket has
more recently accessed, still-allocated blocks. Data in the useful
bucket (with still-allocated blocks) may be evicted in preference to
data in the useless bucket (with old, freed blocks).
On dcenter, we saw that the MFU metadata bucket was 230MB, while the
MFU data bucket was 27GB and the MRU metadata bucket was 256GB.
However, the vast majority of data in the MRU metadata bucket (256GB)
was freed blocks, and thus useless. Meanwhile, the MFU metadata bucket
(230MB) was constantly evicting useful blocks that will be soon needed.
The problem of cache segmentation is a larger problem that needs more
investigation. However, if we stop caching freed blocks, it should
reduce the impact of this more fundamental issue.
MFC after: 2 weeks
* Illumos zfs issue #3137 L2ARC compression
Whether or not to compress buffers entering the L2ARC is
controlled by "compression" setting on the dataset, when
compression is not "off", L2ARC compression is enabled.
The compress method is always LZ4 for L2ARC when enabled
because it works best for the scenario.
MFC after: 2 weeks
Merge vendor bugfix for a possible deadlock related to async destroy
and improve write performance by introducing a new lock protecting
tx_open_txg.
Illumos ZFS issues:
3642 dsl_scan_active() should not issue I/O to determine if async
destroying is active
3643 txg_delay should not hold the tc_lock
MFC after: 1 week
impossible to set quota and reservation on pools lower than version 22.
Problem has been reported and a solution discussed with vendor.
Illumos ZFS issues:
3739 cannot set zfs quota or reservation on pool version < 22
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reported by: Steve Wills <swills@FreeBSD.org>
MFC after: 3 days
Merge bugfixes accepted and integrated by vendor. Underlying problems
have been reported by us and fixed in r240942 and r249196.
Illumos ZFS issues:
3645 dmu_send_impl: possibilty of pool hold leak
3692 Panic on zfs receive of a recursive deduplicated stream
MFC after: 8 days
doesn't copyout in this case.
To solve this issue a new struct zfs_iocparm_t is introduced consisting of:
- zfs_ioctl_version (future backwards compatibility purposes)
- user space pointer to zfs_cmd_t (copyin and copyout)
- size of zfs_cmd_t (verification purposes)
The copyin and copyout of zfs_cmd_t is now done the illumos (vendor) way
what makes porting of new changes easier and ensures correct behavior if
returning an error.
MFC after: 10 days
Do not list read-only pools in zpool.cache
Reduce diff against vendor in unused vdev_disk.c
Illumos ZFS issues:
3639 zpool.cache should skip over readonly pools
3640 want automatic devid updates
MFC after: 1 week
Merge change from vendor to reduce diff only.
ZFS dtrace probes are not supported on FreeBSD yet.
Illumos ZFS issues:
3598 want to dtrace when errors are generated in zfs
MFC after: 3 weeks
Import vendor change to reduce diff, no effect on FreeBSD.
Illumos ZFS issues:
3517 importing pool with autoreplace=on and "hole" vdevs crashes syseventd
Prior to r248571 spa_open was always called with a bare pool name,
but now it is called with a dataset name instead (spa_lookup handles
that).
So, when a ZFS root is mounted spa_open is called with a name of a root
dataset, which can very well be different from the pool name.
But zvol_create_minors should be called with the pool name, because it
performs a recursive traversal of all datasets under the name to find
all those that are volumes.
MFC after: 7 days
This particular scenario was easily reproduced using a NFS export. When the
first 'zfs unmount' occurred, it returned EBUSY via this path, while
vflush() had flushed references on the filesystem's root vnode, which in
turn caused its v_interlock to be destroyed. The next time 'zfs unmount'
was called, vflush() tried to obtain this lock, which caused this panic.
Since vflush() on FreeBSD is a definitive call, there is no need to check
vfsp->vfs_count after it completes. Simply #ifdef sun this check.
Submitted by: avg
Reviewed by: avg
Approved by: ken (mentor)
MFC after: 1 month
Previously TRIM processing was very bursty. This was made worse by the fact
that TRIM requests on SSD's are typically much slower than reads or writes.
This often resulted in stalls while large numbers of TRIM's where processed.
In addition due to the way the TRIM thread was only woken by writes, deletes
could stall in the queue for extensive periods of time.
This patch adds a number of controls to how often the TRIM thread for each
SPA processes its outstanding delete requests.
vfs.zfs.trim.timeout: Delay TRIMs by up to this many seconds
vfs.zfs.trim.txg_delay: Delay TRIMs by up to this many TXGs (reduced to 32)
vfs.zfs.vdev.trim_max_bytes: Maximum pending TRIM bytes for a vdev
vfs.zfs.vdev.trim_max_pending: Maximum pending TRIM segments for a vdev
vfs.zfs.trim.max_interval: Maximum interval between TRIM queue processing
(seconds)
Given the most common TRIM implementation is ATA TRIM the current defaults
are targeted at that.
Reviewed by: pjd (mentor)
Approved by: pjd (mentor)
MFC after: 2 weeks
Currently, the trim module uses the same algorithm for data and cache
devices when deciding to issue TRIM requests, based on how far in the
past the TXG is.
Unfortunately, this is not ideal for cache devices, because the L2ARC
doesn't use the concept of TXGs at all. In fact, when using a pool for
reading only, the L2ARC is written but the TXG counter doesn't
increase, and so no new TRIM requests are issued to the cache device.
This patch fixes the issue by using time instead of the TXG number as
the criteria for trimming on cache devices. The basic delay principle
stays the same, but parameters are expressed in seconds instead of
TXGs. The new parameters are named trim_l2arc_limit and
trim_l2arc_batch, and both default to 30 second.
Reviewed by: pjd (mentor)
Approved by: pjd (mentor)
Obtained from: 17122c31ac
MFC after: 2 weeks
This patch adds some improvements to the way the trim module considers
TXGs:
- Free ZIOs are registered with the TXG from the ZIO itself, not the
current SPA syncing TXG (which may be out of date);
- L2ARC are registered with a zero TXG number, as L2ARC has no concept
of TXGs;
- The TXG limit for issuing TRIMs is now computed from the last synced
TXG, not the currently syncing TXG. Indeed, under extremely unlikely
race conditions, there is a risk we could trim blocks which have been
freed in a TXG that has not finished syncing, resulting in potential
data corruption in case of a crash.
Reviewed by: pjd (mentor)
Approved by: pjd (mentor)
Obtained from: 5b46ad40d9
MFC after: 2 weeks
The trim map inflight writes tree assumes non-conflicting writes, i.e.
that there will never be two simultaneous write I/Os to the same range
on the same vdev. This seemed like a sane assumption; however, in
actual testing, it appears that repair I/Os can very well conflict
with "normal" writes.
I'm not quite sure if these conflicting writes are supposed to happen
or not, but in the mean time, let's ignore repair writes for now. This
should be safe considering that, by definition, we never repair blocks
that are freed.
Reviewed by: pjd (mentor)
Approved by: pjd (mentor)
Obtained from: Source: 6a3cebaf7c
This adds TRIM support to cache vdevs. When ARC buffers are removed
from the L2ARC in arc_hdr_destroy(), arc_release() or l2arc_evict(),
the size previously occupied by the buffer gets scheduled for TRIMming.
As always, actual TRIMs are only issued to the L2ARC after
txg_trim_limit.
Reviewed by: pjd (mentor)
Approved by: pjd (mentor)
Obtained from: 31aae37399
MFC after: 2 weeks
- provide complete backwards compatibility (old utility, new kernel)
- add zfs_cmd_t compatibility mapping in both directions
- determine ioctl address in zfs_ioctl_compat.c
future further optimizations where the vm_object lock will be held
in read mode most of the time the page cache resident pool of pages
are accessed for reading purposes.
The change is mostly mechanical but few notes are reported:
* The KPI changes as follow:
- VM_OBJECT_LOCK() -> VM_OBJECT_WLOCK()
- VM_OBJECT_TRYLOCK() -> VM_OBJECT_TRYWLOCK()
- VM_OBJECT_UNLOCK() -> VM_OBJECT_WUNLOCK()
- VM_OBJECT_LOCK_ASSERT(MA_OWNED) -> VM_OBJECT_ASSERT_WLOCKED()
(in order to avoid visibility of implementation details)
- The read-mode operations are added:
VM_OBJECT_RLOCK(), VM_OBJECT_TRYRLOCK(), VM_OBJECT_RUNLOCK(),
VM_OBJECT_ASSERT_RLOCKED(), VM_OBJECT_ASSERT_LOCKED()
* The vm/vm_pager.h namespace pollution avoidance (forcing requiring
sys/mutex.h in consumers directly to cater its inlining functions
using VM_OBJECT_LOCK()) imposes that all the vm/vm_pager.h
consumers now must include also sys/rwlock.h.
* zfs requires a quite convoluted fix to include FreeBSD rwlocks into
the compat layer because the name clash between FreeBSD and solaris
versions must be avoided.
At this purpose zfs redefines the vm_object locking functions
directly, isolating the FreeBSD components in specific compat stubs.
The KPI results heavilly broken by this commit. Thirdy part ports must
be updated accordingly (I can think off-hand of VirtualBox, for example).
Sponsored by: EMC / Isilon storage division
Reviewed by: jeff
Reviewed by: pjd (ZFS specific review)
Discussed with: alc
Tested by: pho
- Capability is no longer separate descriptor type. Now every descriptor
has set of its own capability rights.
- The cap_new(2) system call is left, but it is no longer documented and
should not be used in new code.
- The new syscall cap_rights_limit(2) should be used instead of
cap_new(2), which limits capability rights of the given descriptor
without creating a new one.
- The cap_getrights(2) syscall is renamed to cap_rights_get(2).
- If CAP_IOCTL capability right is present we can further reduce allowed
ioctls list with the new cap_ioctls_limit(2) syscall. List of allowed
ioctls can be retrived with cap_ioctls_get(2) syscall.
- If CAP_FCNTL capability right is present we can further reduce fcntls
that can be used with the new cap_fcntls_limit(2) syscall and retrive
them with cap_fcntls_get(2).
- To support ioctl and fcntl white-listing the filedesc structure was
heavly modified.
- The audit subsystem, kdump and procstat tools were updated to
recognize new syscalls.
- Capability rights were revised and eventhough I tried hard to provide
backward API and ABI compatibility there are some incompatible changes
that are described in detail below:
CAP_CREATE old behaviour:
- Allow for openat(2)+O_CREAT.
- Allow for linkat(2).
- Allow for symlinkat(2).
CAP_CREATE new behaviour:
- Allow for openat(2)+O_CREAT.
Added CAP_LINKAT:
- Allow for linkat(2). ABI: Reuses CAP_RMDIR bit.
- Allow to be target for renameat(2).
Added CAP_SYMLINKAT:
- Allow for symlinkat(2).
Removed CAP_DELETE. Old behaviour:
- Allow for unlinkat(2) when removing non-directory object.
- Allow to be source for renameat(2).
Removed CAP_RMDIR. Old behaviour:
- Allow for unlinkat(2) when removing directory.
Added CAP_RENAMEAT:
- Required for source directory for the renameat(2) syscall.
Added CAP_UNLINKAT (effectively it replaces CAP_DELETE and CAP_RMDIR):
- Allow for unlinkat(2) on any object.
- Required if target of renameat(2) exists and will be removed by this
call.
Removed CAP_MAPEXEC.
CAP_MMAP old behaviour:
- Allow for mmap(2) with any combination of PROT_NONE, PROT_READ and
PROT_WRITE.
CAP_MMAP new behaviour:
- Allow for mmap(2)+PROT_NONE.
Added CAP_MMAP_R:
- Allow for mmap(PROT_READ).
Added CAP_MMAP_W:
- Allow for mmap(PROT_WRITE).
Added CAP_MMAP_X:
- Allow for mmap(PROT_EXEC).
Added CAP_MMAP_RW:
- Allow for mmap(PROT_READ | PROT_WRITE).
Added CAP_MMAP_RX:
- Allow for mmap(PROT_READ | PROT_EXEC).
Added CAP_MMAP_WX:
- Allow for mmap(PROT_WRITE | PROT_EXEC).
Added CAP_MMAP_RWX:
- Allow for mmap(PROT_READ | PROT_WRITE | PROT_EXEC).
Renamed CAP_MKDIR to CAP_MKDIRAT.
Renamed CAP_MKFIFO to CAP_MKFIFOAT.
Renamed CAP_MKNODE to CAP_MKNODEAT.
CAP_READ old behaviour:
- Allow pread(2).
- Disallow read(2), readv(2) (if there is no CAP_SEEK).
CAP_READ new behaviour:
- Allow read(2), readv(2).
- Disallow pread(2) (CAP_SEEK was also required).
CAP_WRITE old behaviour:
- Allow pwrite(2).
- Disallow write(2), writev(2) (if there is no CAP_SEEK).
CAP_WRITE new behaviour:
- Allow write(2), writev(2).
- Disallow pwrite(2) (CAP_SEEK was also required).
Added convinient defines:
#define CAP_PREAD (CAP_SEEK | CAP_READ)
#define CAP_PWRITE (CAP_SEEK | CAP_WRITE)
#define CAP_MMAP_R (CAP_MMAP | CAP_SEEK | CAP_READ)
#define CAP_MMAP_W (CAP_MMAP | CAP_SEEK | CAP_WRITE)
#define CAP_MMAP_X (CAP_MMAP | CAP_SEEK | 0x0000000000000008ULL)
#define CAP_MMAP_RW (CAP_MMAP_R | CAP_MMAP_W)
#define CAP_MMAP_RX (CAP_MMAP_R | CAP_MMAP_X)
#define CAP_MMAP_WX (CAP_MMAP_W | CAP_MMAP_X)
#define CAP_MMAP_RWX (CAP_MMAP_R | CAP_MMAP_W | CAP_MMAP_X)
#define CAP_RECV CAP_READ
#define CAP_SEND CAP_WRITE
#define CAP_SOCK_CLIENT \
(CAP_CONNECT | CAP_GETPEERNAME | CAP_GETSOCKNAME | CAP_GETSOCKOPT | \
CAP_PEELOFF | CAP_RECV | CAP_SEND | CAP_SETSOCKOPT | CAP_SHUTDOWN)
#define CAP_SOCK_SERVER \
(CAP_ACCEPT | CAP_BIND | CAP_GETPEERNAME | CAP_GETSOCKNAME | \
CAP_GETSOCKOPT | CAP_LISTEN | CAP_PEELOFF | CAP_RECV | CAP_SEND | \
CAP_SETSOCKOPT | CAP_SHUTDOWN)
Added defines for backward API compatibility:
#define CAP_MAPEXEC CAP_MMAP_X
#define CAP_DELETE CAP_UNLINKAT
#define CAP_MKDIR CAP_MKDIRAT
#define CAP_RMDIR CAP_UNLINKAT
#define CAP_MKFIFO CAP_MKFIFOAT
#define CAP_MKNOD CAP_MKNODAT
#define CAP_SOCK_ALL (CAP_SOCK_CLIENT | CAP_SOCK_SERVER)
Sponsored by: The FreeBSD Foundation
Reviewed by: Christoph Mallon <christoph.mallon@gmx.de>
Many aspects discussed with: rwatson, benl, jonathan
ABI compatibility discussed with: kib
Import a fix tighten assertion on SPA versions from vendor (Illumos).
Illumos ZFS issue:
3543 Feature flags causes assertion in spa.c to miss certain cases
MFC after: 2 weeks
Merge new read-only zfs properties from vendor (illumos)
Illumos ZFS issues:
3588 provide zfs properties for logical (uncompressed) space used and
referenced
References:
https://www.illumos.org/issues/3588
MFC after: 2 weeks
in r247265 (ZFS deadman thread). Both new utilities now support the old
kernel and new kernel properly detects old utilities.
For future backwards compatibility, the vfs.zfs.version.ioctl read-only
sysctl has been introduced. With this sysctl zfs utilities will be able
to detect the ioctl interface version of the currently loaded zfs module.
As a side effect, the zfs utilities between r247265 and this revision don't
support the old kernel module. If you are using HEAD newer or equal than
r247265, install the new kernel module (or whole kernel) first.
MFC after: 10 days
Merge the ZFS I/O deadman thread from vendor (illumos).
This feature panics the system on hanging ZFS I/O, helps debugging
and resumes failed service.
The panic behavior can be controlled with the loader-only tunables:
vfs.zfs.deadman_enabled (enable or disable panic on stalled ZFS I/O)
vfs.zfs.deadman_synctime (expiration time for stalled ZFS I/O)
By default, ZFS I/O deadman is enabled by default on amd64 and i386
excluding virtual guest machines.
Illumos ZFS issues:
3246 ZFS I/O deadman thread
References:
https://www.illumos.org/issues/3246
MFC after: 2 weeks
Fixes several problems if working with read-only pools.
Changed code originaly introduced in onnv-gate 13061:bda0decf867b
Contains changes up to illumos-gate 13700:4bc0783f6064
PR: kern/175897
Suggested by: avg
MFC after: 2 weeks
Import vendor bugfixes regarding SA rounding, header size and layout.
This was already partially fixed by avg.
Illumos ZFS issues:
3512 rounding discrepancy in sa_find_sizes()
3513 mismatch between SA header size and layout
References:
https://www.illumos.org/issues/3512https://www.illumos.org/issues/3513
MFC after: 2 weeks
* Illumos zfs issue #3035 [1] LZ4 compression support in ZFS.
LZ4 is a new high-speed BSD-licensed compression algorithm created
by Yann Collet that delivers very high compression and decompression
performance compared to lzjb (>50% faster on compression, >80% faster
on decompression and around 3x faster on compression of incompressible
data), while giving better compression ratio [1].
This version of LZ4 corresponds to upstream's [2] revision 85.
Please note that for obvious reasons this is not backward read
compatible. This means once a pool have LZ4 compressed data, these
data can no longer be read by older ZFS implementations.
Local changes:
- On-stack hash table disabled and using kernel slab allocator
instead, at this time. This requires larger kernel thread stack
for zio workers. This may change in the future should we adjusted
the zio workers' thread stack size.
- likely and unlikely will be undefined if they are already defined,
this is required for i386 XEN build.
- Removed De Bruijn sequence based __builtin_ctz family of builtins
in favor of the latter. Both GCC and clang supports these builtins.
- Changed the way the LZ4 code detects endianness.
- Manual pages modifications to mention the feature based on Illumos
counterpart.
- Boot loader changes to make it support LZ4 decompression.
[1] https://www.illumos.org/issues/3035
[2] http://code.google.com/p/lz4/source/list
Obtained from: Illumos (13921:9d721847e469)
Tested on: FreeBSD/amd64
MFC after: 1 month
A special gfs vnode corresponds to that object.
A regular zfs vnode must not be returned.
This should be upstreamed.
Reported by: pluknet
Submitted by: rmacklem
Tested by: pluknet
MFC after: 10 days
Now they are split into two pairs: page_hold/page_unhold for mappedread
and page_busy/page_unbusy for update_pages.
For mappedread we simply hold a page that is to be used as a source if it
is resident and valid (and not busy). This is sufficient since we are
only doing page -> user buffer copying. There is no page <-> backing
storage I/O involved.
update_pages is now better split to properly handle the putpages case
(page -> arc) and the regular write case (arc -> page).
For the latter we use complete protocol of marking an object with
paging-in-progress and marking a page with io_start (busy count).
Also, in this case we remove the write bit from all page mappings and
clear dirty bits of the pages, the former is needed to ensure that the
latter does the right thing.
Additionally we update a page if it is cached instead of just freeing it
as was done before. This needs to be verified.
A minor detail: ZFS-backed pages should always be either fully valid
or fully invalid. Assert this and use simpler API that does not deal
with sub-page blocks.
Reviewed by: kib
MFC after: 26 days
This should allow the kernel linker to easily detect a situation
when the module is present both in a kernel and in a preloaded file
(zfs.ko).
Reviewed by: jhb
MFC after: 5 days
It seems that old ZFS versions (v15) completely omit "vdev_children"
property when there is a single child.
Reported by: jase
Tested by: jase
MFC after: 1 week
