There's no need to call iov_iter_advance() in zpl_iter_read().
This was preserved from the previous code where it wasn't needed
but also didn't cause any problems. Now that the iter functions
also handle pipes that's no longer the case. When fully reading a
pipe buffer iov_iter_advance() may results in the pipe buf release
function being called which will not be registered resulting in
a NULL dereference.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#11375Closes#11378
As of the 5.10 kernel the generic splice compatibility code has been
removed. All filesystems are now responsible for registering a
->splice_read and ->splice_write callback to support this operation.
The good news is the VFS provided generic_file_splice_read() and
iter_file_splice_write() callbacks can be used provided the ->iter_read
and ->iter_write callback support pipes. However, this is currently
not the case and only iovecs and bvecs (not pipes) are ever attached
to the uio structure.
This commit changes that by allowing full iov_iter structures to be
attached to uios. Ever since the 4.9 kernel the iov_iter structure
has supported iovecs, kvecs, bvevs, and pipes so it's desirable to
pass the entire thing when possible. In conjunction with this the
uio helper functions (i.e uiomove(), uiocopy(), etc) have been
updated to understand the new UIO_ITER type.
Note that using the kernel provided uio_iter interfaces allowed the
existing Linux specific uio handling code to be simplified. When
there's no longer a need to support kernel's older than 4.9, then
it will be possible to remove the iovec and bvec members from the
uio structure and always use a uio_iter. Until then we need to
maintain all of the existing types for older kernels.
Some additional refactoring and cleanup was included in this change:
- Added checks to configure to detect available iov_iter interfaces.
Some are available all the way back to the 3.10 kernel and are used
when available. In particular, uio_prefaultpages() now always uses
iov_iter_fault_in_readable() which is available for all supported
kernels.
- The unused UIO_USERISPACE type has been removed. It is no longer
needed now that the uio_seg enum is platform specific.
- Moved zfs_uio.c from the zcommon.ko module to the Linux specific
platform code for the zfs.ko module. This gets it out of libzfs
where it was never needed and keeps this Linux specific code out
of the common sources.
- Removed unnecessary O_APPEND handling from zfs_iter_write(), this
is redundant and O_APPEND is already handled in zfs_write();
NOTE: Cleanly applying this kernel compatibility change required
applying the following commits. This makes the change larger than
it absolutely needs to be, but the resulting code matches what's in
the branch branch. This is both more tested and makes it easier to
apply any future backports in this area.
7cf4cd824 Remove incorrect assertion
783be694f Reduce confusion in zfs_write
af5626ac2 Return EFAULT at the end of zfs_write() when set
cc1f85be8 Simplify offset and length limit in zfs_write
9585538d0 Const some unchanging variables in zfs_write
86e74dc16 Remove redundant oid parameter to update_pages
b3d723fb0 Factor uid, gid, and projid out of loop in zfs_write
3d40b6554 Share zfs_fsync, zfs_read, zfs_write, et al between Linux and FreeBSD
Reviewed-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#11351
The oid comes from the znode we are already passing.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matt Macy <mmacy@FreeBSD.org>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#11176
The zfs_fsync, zfs_read, and zfs_write function are almost identical
between Linux and FreeBSD. With a little refactoring they can be
moved to the common code which is what is done by this commit.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#11078
Resolve an uninitialized variable warning when compiling.
In function ‘zfs_domount’:
warning: ‘root_inode’ may be used uninitialized in this
function [-Wmaybe-uninitialized]
sb->s_root = d_make_root(root_inode);
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#11306
- Don't leave fstrans set when passed a snapshot
- Don't remove minor if volmode already matches new value
- (FreeBSD) Wait for GEOM ops to complete before trying
remove (at create time GEOM will be "tasting" in parallel)
- (FreeBSD) Don't leak zvol_state_lock on open if zv == NULL
- (FreeBSD) Don't try to unlock zv->zv_state lock if zv == NULL
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#11199
The ZFS_ENTER/ZFS_EXIT/ZFS_VERFY_ZP macros should not be used
in the Linux zpl_*.c source files. They return a positive error
value which is correct for the common code, but not for the Linux
specific kernel code which expects a negative return value. The
ZPL_ENTER/ZPL_EXIT/ZPL_VERFY_ZP macros should be used instead.
Furthermore, the ZPL_EXIT macro has been updated to not call the
zfs_exit_fs() function. This prevents a possible deadlock which
can occur when a snapshot is automatically unmounted because the
zpl_show_devname() must never wait on in progress automatic
snapshot unmounts.
Reviewed-by: Adam Moss <c@yotes.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#11169Closes#11201
The custom zpl_show_devname() helper should translate spaces in
to the octal escape sequence \040. The getmntent(2) function
is aware of this convention and properly translates the escape
character back to a space when reading the fsname.
Without this change the `zfs mount` and `zfs unmount` commands
incorrectly detect when a dataset with a name containing spaces
is mounted.
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#11182Closes#11187
The microzap hash can sometimes be zero for single digit snapnames.
The zap cursor can then have a serialized value of two (for . and ..),
and skip the first entry in the avl tree for the .zfs/snapshot directory
listing, and therefore does not return all snapshots.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Cedric Berger <cedric@precidata.com>
Signed-off-by: Tony Perkins <tperkins@datto.com>
Closes#11039
The field is yet another leftover from unsupported zfs_znode_move.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Closes#11186
A new function was added named revalidate_disk_size() and the old
revalidate_disk() appears to have been deprecated. As the only ZFS
code that calls this function is zvol_update_volsize, swapping the
old function call out for the new one should be all that is required.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes#11085
Kernel 5.10 removed check_disk_change() in favor of callers using
the faster bdev_check_media_change() instead, and explicitly forcing
bdev revalidation when they desire that behavior. To preserve prior
behavior, I have wrapped this into a zfs_check_media_change() macro
that calls an inline function for the new API that mimics the old
behavior when check_disk_change() doesn't exist, and just calls
check_disk_change() if it exists.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes#11085
Kernel commit 2b0d3d3e4fcfb brought in some changes to the struct
percpu_ref structure that moves most of its fields into a member
struct named "data" of type struct percpu_ref_data. This includes
the "count" member which is updated by vdev_blkg_tryget(), so update
this function to chase the API change, and detect it via configure.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes#11085
Using more specific assert variants gives better messages on failure.
No functional change.
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Matt Macy <mmacy@FreeBSD.org>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#11117
Refer to the correct section or alternative for FreeBSD and Linux.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#11132
The port removed provisions for zfs_znode_move but the cleanup missed
this bit. To quote the original:
[snip]
list_insert_tail(&zfsvfs->z_all_znodes, zp);
membar_producer();
/*
* Everything else must be valid before assigning z_zfsvfs makes the
* znode eligible for zfs_znode_move().
*/
zp->z_zfsvfs = zfsvfs;
[/snip]
In the current code it is immediately followed by unlock which issues
the same fence, thus plays no role in correctness.
Reviewed-by: Matt Macy <mmacy@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Closes#11115
The acltype property is currently hidden on FreeBSD and does not
reflect the NFSv4 style ZFS ACLs used on the platform. This makes it
difficult to observe that a pool imported from FreeBSD on Linux has a
different type of ACL that is being ignored, and vice versa.
Add an nfsv4 acltype and expose the property on FreeBSD.
Make the default acltype nfsv4 on FreeBSD.
Setting acltype to an unhanded style is treated the same as setting
it to off. The ACLs will not be removed, but they will be ignored.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#10520
The value of zp is used without having been initialized under some
conditions. Initialize the pointer to NULL.
Add a regression test case using chown in acl/posix. However, this is
not enough because the setup sets xattr=sa, which means zfs_setattr_dir
will not be called. Create a second group of acl tests in acl/posix-sa
duplicating the acl/posix tests with symlinks, and remove xattr=sa from
the original acl/posix tests. This provides more coverage for the
default xattr=on code.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#10043Closes#11025
In C, const indicates to the reader that mutation will not occur.
It can also serve as a hint about ownership.
Add const in a few places where it makes sense.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes#10997
With PREEMPTION=y and BLK_CGROUP=y preempt_schedule_notrace() is being
used on arm64 which is a GPL-only function and hence the build of the
DKMS kernel module fails.
Fix that by redefining preempt_schedule_notrace() to preempt_schedule()
which should be safe as long as tracing is not used.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Closes#8545Closes#9948Closes#10416Closes#10973
The procfs_list interface is required by several kstats. Implement
this functionality for FreeBSD to provide access to these kstats.
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#10890
== Motivation and Context
The new vdev ashift optimization prevents the removal of devices when
a zfs configuration is comprised of disks which have different logical
and physical block sizes. This is caused because we set 'spa_min_ashift'
in vdev_open and then later call 'vdev_ashift_optimize'. This would
result in an inconsistency between spa's ashift calculations and that
of the top-level vdev.
In addition, the optimization logical ignores the overridden ashift
value that would be provided by '-o ashift=<val>'.
== Description
This change reworks the vdev ashift optimization so that it's only
set the first time the device is configured. It still allows the
physical and logical ahsift values to be set every time the device
is opened but those values are only consulted on first open.
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Cedric Berger <cedric@precidata.com>
Signed-off-by: George Wilson <gwilson@delphix.com>
External-Issue: DLPX-71831
Closes#10932
When expanding a device zfs needs to rescan the partition table to
get the correct size. This can only happen when we're in the kernel
and requires the device to be closed. As part of the rescan, udev is
notified and the device links are removed and recreated. This leave a
window where the vdev code may try to reopen the device before udev
has recreated the link. If that happens, then the pool may end up in
a suspended state.
To correct this, we leverage the BLKPG_RESIZE_PARTITION ioctl which
allows the partition information to be modified even while it's in use.
This ioctl also does not remove the device link associated with the zfs
data partition so it eliminates the race condition that can occur in
the kernel.
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Wilson <gwilson@delphix.com>
Closes#10897
In zpl_mount_impl, there is:
dmu_objset_hold ; returns with pool & ds held
dsl_pool_rele
sget
dsl_dataset_rele
As spelled out in the "DSL Pool Configuration Lock" in dsl_pool.c,
this requires a long hold.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Paul Zuchowski <pzuchowski@datto.com>
Signed-off-by: John Poduska <jpoduska@datto.com>
Closes#10936
Prefer acltype=off|posix, retaining the old names as aliases.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#10918
Use ZFS_ENTER and ZFS_EXIT to protect datasets while their mount
devname is being retrieved.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#10892Closes#10927
Allow to rename file systems without remounting if it is possible.
It is possible for file systems with 'mountpoint' property set to
'legacy' or 'none' - we don't have to change mount directory for them.
Currently such file systems are unmounted on rename and not even
mounted back.
This introduces layering violation, as we need to update
'f_mntfromname' field in statfs structure related to mountpoint (for
the dataset we are renaming and all its children).
In my opinion it is worth it, as it allow to update FreeBSD in even
cleaner way - in ZFS-only configuration root file system is ZFS file
system with 'mountpoint' property set to 'legacy'. If root dataset is
named system/rootfs, we can snapshot it (system/rootfs@upgrade), clone
it (system/oldrootfs), update FreeBSD and if it doesn't boot we can
boot back from system/oldrootfs and rename it back to system/rootfs
while it is mounted as /. Before it was not possible, because
unmounting / was not possible.
Authored by: Pawel Jakub Dawidek <pjd@FreeBSD.org>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported by: Matt Macy <mmacy@freebsd.org>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#10839
Initially it was considered simplest to stub out all
of the functions on FreeBSD. Now that FreeBSD supports
KSTAT_TYPE_RAW at least some of the functionality should
be made available.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#10842
Commit dcdc12e added compatibility code to treat NR_SLAB_RECLAIMABLE_B
as if it were the same as NR_SLAB_RECLAIMABLE. However, the new value
is in bytes while the old value was in pages which means they are not
interchangeable.
The only place the reclaimable slab size is used is as a component of
the calculation done by arc_free_memory(). This function returns the
amount of memory the ARC considers to be free or reclaimable at little
cost. Rather than switch to a new interface to get this value it has
been removed it from the calculation. It is normally a minor component
compared to the number of inactive or free pages, and removing it
aligns the behavior with the FreeBSD version of arc_free_memory().
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Coleman Kane <ckane@colemankane.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#10834
The cache of struct svc_export and struct svc_expkey by nfsd and
rpc.mountd for the snapshot holds references to the mount point.
We need to flush them out before unmounting, otherwise umount
would fail with EBUSY.
Reviewed-by: Don Brady <don.brady@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Youzhong Yang <yyang@mathworks.com>
Closes#6000Closes#10783
In absence of inheriting entry for owner@, group@, or everyone@,
zfs_acl_chmod() is called to set these. This can cause confusion for Samba
admins who do not expect these entries to appear on newly created files and
directories once they have been stripped from from the parent directory.
When aclmode is set to "restricted", chmod is prevented on non-trivial ACLs.
It is not a stretch to assume that in this case the administrator does not want
ZFS to add the missing special entries. Add check for this aclmode, and if an
inherited entry is present skip zfs_acl_chmod().
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Andrew Walker <awalker@ixsystems.com>
Closes#10748
Many modern devices use physical allocation units that are much
larger than the minimum logical allocation size accessible by
external commands. Two prevalent examples of this are 512e disk
drives (512b logical sector, 4K physical sector) and flash devices
(512b logical sector, 4K or larger allocation block size, and 128k
or larger erase block size). Operations that modify less than the
physical sector size result in a costly read-modify-write or garbage
collection sequence on these devices.
Simply exporting the true physical sector of the device to ZFS would
yield optimal performance, but has two serious drawbacks:
1. Existing pools created with devices that have different logical
and physical block sizes, but were configured to use the logical
block size (e.g. because the OS version used for pool construction
reported the logical block size instead of the physical block
size) will suddenly find that the vdev allocation size has
increased. This can be easily tolerated for active members of
the array, but ZFS would prevent replacement of a vdev with
another identical device because it now appears that the smaller
allocation size required by the pool is not supported by the new
device.
2. The device's physical block size may be too large to be supported
by ZFS. The optimal allocation size for the vdev may be quite
large. For example, a RAID controller may export a vdev that
requires read-modify-write cycles unless accessed using 64k
aligned/sized requests. ZFS currently has an 8k minimum block
size limit.
Reporting both the logical and physical allocation sizes for vdevs
solves these problems. A device may be used so long as the logical
block size is compatible with the configuration. By comparing the
logical and physical block sizes, new configurations can be optimized
and administrators can be notified of any existing pools that are
sub-optimal.
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Matthew Macy <mmacy@freebsd.org>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#10619
We limit the size of nvlists passed to the kernel so a user cannot make
the kernel do an unreasonably large allocation. On FreeBSD this limit
was 128 kiB, which turns out to be a bit too small when doing some
operations involving a large number of datasets or snapshots, for
example replication.
Make this limit tunable, with a platform-specific auto default.
Linux keeps its limit at KMALLOC_MAX_SIZE. FreeBSD uses 1/4 of the
system limit on user wired memory, which allows it to scale depending
on system configuration.
Reviewed-by: Matt Macy <mmacy@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Issue #6572Closes#10706
The ARC caches data in scatter ABD's, which are collections of pages,
which are typically 4K. Therefore, the space used to cache each block
is rounded up to a multiple of 4K. The ABD subsystem tracks this wasted
memory in the `scatter_chunk_waste` kstat. However, the ARC's `size` is
not aware of the memory used by this round-up, it only accounts for the
size that it requested from the ABD subsystem.
Therefore, the ARC is effectively using more memory than it is aware of,
due to the `scatter_chunk_waste`. This impacts observability, e.g.
`arcstat` will show that the ARC is using less memory than it
effectively is. It also impacts how the ARC responds to memory
pressure. As the amount of `scatter_chunk_waste` changes, it appears to
the ARC as memory pressure, so it needs to resize `arc_c`.
If the sector size (`1<<ashift`) is the same as the page size (or
larger), there won't be any waste. If the (compressed) block size is
relatively large compared to the page size, the amount of
`scatter_chunk_waste` will be small, so the problematic effects are
minimal.
However, if using 512B sectors (`ashift=9`), and the (compressed) block
size is small (e.g. `compression=on` with the default `volblocksize=8k`
or a decreased `recordsize`), the amount of `scatter_chunk_waste` can be
very large. On a production system, with `arc_size` at a constant 50%
of memory, `scatter_chunk_waste` has been been observed to be 10-30% of
memory.
This commit adds `scatter_chunk_waste` to `arc_size`, and adds a new
`waste` field to `arcstat`. As a result, the ARC's memory usage is more
observable, and `arc_c` does not need to be adjusted as frequently.
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#10701
Linux and FreeBSD will most likely never see this issue.
On macOS when kext is unloaded, but zed is still connected, zed
will be issued ENODEV. As the cdevsw is released, the kernel
will not have zfsdev_release() called to release minor/onexit/events,
and it "leaks". This ensures it is cleaned up before unload.
Changed the for loop from zsprev, to zsnext style, for less
code duplication.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Jorgen Lundman <lundman@lundman.net>
Closes#10700
The make_request_fn and associated API was replaced recently in a
Linux 5.9 merge, to replace its functionality with a new submit_bio
member in struct block_device_operations.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes#10696
The ARC shrinker callback `arc_shrinker_count/_scan()` is invoked by the
kernel's shrinker mechanism when the system is running low on free
pages. This happens via 2 code paths:
1. "direct reclaim": The system is attempting to allocate a page, but we
are low on memory. The ARC shrinker callback is invoked from the
page-allocation code path.
2. "indirect reclaim": kswapd notices that there aren't many free pages,
so it invokes the ARC shrinker callback.
In both cases, the kernel's shrinker code requests that the ARC shrinker
callback release some of its cache, and then it measures how many pages
were released. However, it's measurement of released pages does not
include pages that are freed via `__free_pages()`, which is how the ARC
releases memory (via `abd_free_chunks()`). Rather, the kernel shrinker
code is looking for pages to be placed on the lists of reclaimable pages
(which is separate from actually-free pages).
Because the kernel shrinker code doesn't detect that the ARC has
released pages, it may call the ARC shrinker callback many times,
resulting in the ARC "collapsing" down to `arc_c_min`. This has several
negative impacts:
1. ZFS doesn't use RAM to cache data effectively.
2. In the direct reclaim case, a single page allocation may wait a long
time (e.g. more than a minute) while we evict the entire ARC.
3. Even with the improvements made in 67c0f0dedc ("ARC shrinking blocks
reads/writes"), occasionally `arc_size` may stay above `arc_c` for the
entire time of the ARC collapse, thus blocking ZFS read/write operations
in `arc_get_data_impl()`.
To address these issues, this commit limits the ways that the ARC
shrinker callback can be used by the kernel shrinker code, and mitigates
the impact of arc_is_overflowing() on ZFS read/write operations.
With this commit:
1. We limit the amount of data that can be reclaimed from the ARC via
the "direct reclaim" shrinker. This limits the amount of time it takes
to allocate a single page.
2. We do not allow the ARC to shrink via kswapd (indirect reclaim).
Instead we rely on `arc_evict_zthr` to monitor free memory and reduce
the ARC target size to keep sufficient free memory in the system. Note
that we can't simply rely on limiting the amount that we reclaim at once
(as for the direct reclaim case), because kswapd's "boosted" logic can
invoke the callback an unlimited number of times (see
`balance_pgdat()`).
3. When `arc_is_overflowing()` and we want to allocate memory,
`arc_get_data_impl()` will wait only for a multiple of the requested
amount of data to be evicted, rather than waiting for the ARC to no
longer be overflowing. This allows ZFS reads/writes to make progress
even while the ARC is overflowing, while also ensuring that the eviction
thread makes progress towards reducing the total amount of memory used
by the ARC.
4. The amount of memory that the ARC always tries to keep free for the
rest of the system, `arc_sys_free` is increased.
5. Now that the shrinker callback is able to provide feedback to the
kernel's shrinker code about our progress, we can safely enable
the kswapd hook. This will allow the arc to receive notifications
when memory pressure is first detected by the kernel. We also
re-enable the appropriate kstats to track these callbacks.
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: George Wilson <george.wilson@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#10600
Renamed to avoid conflicting with refcount.h when a different
implementation is already provided by the platform.
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#10620
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#10623
The process of evicting data from the ARC is referred to as
`arc_adjust`.
This commit changes the term to `arc_evict`, which is more specific.
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#10592
Stock kernels older than 4.10 do not export the has_capability()
function which is required by commit e59a377. To avoid breaking
the build on older kernels revert to the safe legacy behavior and
return EACCES when privileges cannot be checked.
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Matt Ahrens <matt@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#10565Closes#10573
`arc_free_memory()` returns the amount of memory that the ARC considers
to be free. This includes pages that are not actually free, but can be
evicted with essentially zero cost (without doing any i/o), for example
the page cache. The ARC can "squeeze out" any pages included in this
calculation, leaving only `arc_sys_free` (1/64th of RAM) for these
free/evictable pages.
Included in the count of free/evictable pages is
`nr_inactive_anon_pages()`, which is described as "Anonymous memory that
has not been used recently and can be swapped out". These pages would
have to be written out to disk (swap) in order to evict them, and they
are not included in `/proc/meminfo`'s `MemAvailable`.
Therefore it is not appropriate for `nr_inactive_anon_pages()` to be
included in the free/evictable memory returned by `arc_free_memory()`,
because the ARC shouldn't (intentionally) make the system swap.
This commit removes `nr_inactive_anon_pages()` from the memory returned
by `arc_free_memory()`. This is a step towards enabling the ARC to
manage free memory by monitoring it and reducing the ARC size as we
notice that there is insufficient free memory (in the `arc_reap_zthr`),
rather than the current method of relying on the `arc_shrinker`
callback.
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#10575
The filesystem_limit and snapshot_limit properties limit the number of
filesystems or snapshots that can be created below this dataset.
According to the manpage, "The limit is not enforced if the user is
allowed to change the limit." Two types of users are allowed to change
the limit:
1. Those that have been delegated the `filesystem_limit` or
`snapshot_limit` permission, e.g. with
`zfs allow USER filesystem_limit DATASET`. This works properly.
2. A user with elevated system privileges (e.g. root). This does not
work - the root user will incorrectly get an error when trying to create
a snapshot/filesystem, if it exceeds the `_limit` property.
The problem is that `priv_policy_ns()` does not work if the `cred_t` is
not that of the current process. This happens when
`dsl_enforce_ds_ss_limits()` is called in syncing context (as part of a
sync task's check func) to determine the permissions of the
corresponding user process.
This commit fixes the issue by passing the `task_struct` (typedef'ed as
a `proc_t`) to syncing context, and then using `has_capability()` to
determine if that process is privileged. Note that we still need to
pass the `cred_t` to syncing context so that we can check if the user
was delegated this permission with `zfs allow`.
This problem only impacts Linux. Wrappers are added to FreeBSD but it
continues to use `priv_check_cred()`, which works on arbitrary `cred_t`.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#8226Closes#10545
OS-specific code (e.g. under `module/os/linux`) does not need to share
its code structure with any other operating systems. In particular, the
ARC and kmem code need not be similar to the code in illumos, because we
won't be syncing this OS-specific code between operating systems. For
example, if/when illumos support is added to the common repo, we would
add a file `module/os/illumos/zfs/arc_os.c` for the illumos versions of
this code.
Therefore, we can simplify the code in the OS-specific ARC and kmem
routines.
These changes do not impact system behavior, they are purely code
cleanup. The changes are:
Arenas are not used on Linux or FreeBSD (they are always `NULL`), so
`heap_arena`, `zio_arena`, and `zio_alloc_arena` can be removed, along
with code that uses them.
In `arc_available_memory()`:
* `desfree` is unused, remove it
* rename `freemem` to avoid conflict with pre-existing `#define`
* remove checks related to arenas
* use units of bytes, rather than converting from bytes to pages and
then back to bytes
`SPL_KMEM_CACHE_REAP` is unused, remove it.
`skc_reap` is unused, remove it.
The `count` argument to `spl_kmem_cache_reap_now()` is unused, remove
it.
`vmem_size()` and associated type and macros are unused, remove them.
In `arc_memory_throttle()`, use a less confusing variable name to store
the result of `arc_free_memory()`.
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#10499
The SPL provides a wrapper for the kernel's shrinker callbacks, which
enables the ZFS code to interface with multiple versions of the shrinker
API's from different kernel versions. Specifically, Linux kernels 3.0 -
3.11 has a single "combined" callback, and Linux kernels 3.12 and later
have two "split" callbacks. The SPL provides a wrapper function so that
the ZFS code only needs to implement one version of the callbacks.
Currently the SPL's wrappers are designed such that the ZFS code
implements the older, "combined" callback. There are a few downsides to
this approach:
* The general design within ZFS is for the latest Linux kernel to be
considered the "first class" API.
* The newer, "split" callback API is easier to understand, because each
callback has one purpose.
* The current wrappers do not completely abstract out the differing
API's, so ZFS code needs `#ifdef` code to handle the differing return
values required for different kernel versions.
This commit addresses these drawbacks by having the ZFS code provide the
latest, "split" callbacks, and the SPL provides a wrapping function for
the older, "combined" API.
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#10502
ZFS registers a memory hook, `__arc_shrinker_func`, which is supposed to
allow the ARC to shrink when the kernel experiences memory pressure.
The ARC shrinker changes `arc_c` via a call to
`arc_reduce_target_size()`. Before commit 3ec34e5527, the ARC
shrinker would also evict data from the ARC to bring `arc_size` down to
the new `arc_c`. However, that commit (seemingly inadvertently) made it
so that the ARC shrinker no longer evicts any data or waits for eviction
to complete.
Repeated calls to the ARC shrinker can reduce `arc_c` drastically, often
all the way to `arc_c_min`. Since it doesn't wait for the actual
eviction of data from the ARC, this creates a situation where `arc_size`
is more than `arc_c` for the several seconds/minutes it takes for
`arc_adjust_zthr` to evict data from the ARC. During this time,
arc_get_data_impl() will block, so ZFS can't process read/write requests
(e.g. from iSCSI, NFS, or read/write syscalls).
To ensure that `arc_c` doesn't shrink faster than the adjust thread can
keep up, this commit makes the ARC shrinker wait for the eviction to
complete, resulting in similar behavior to what we had before commit
3ec34e5527.
Note: commit 3ec34e5527 is `OpenZFS 9284 - arc_reclaim_thread
has 2 jobs` and was integrated in December 2018, and is part of ZoL
0.8.x but not 0.7.x.
Additionally, when the ARC size is reduced drastically, the
`arc_adjust_zthr` can be on-CPU for many seconds without blocking. Any
threads that are bound to the same CPU that arc_adjust_zthr is running
on will not able to run for a long time.
To ensure that CPU-bound threads can make progress, this commit changes
`arc_evict_state_impl()` make a voluntary preemption call,
`cond_resched()`.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Prakash Surya <prakash.surya@delphix.com>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
External-issue: DLPX-70703
Closes#10496
This tunable required a handler to be implemented for
ZFS_MODULE_PARAM_CALL.
Add the handler so the tunable can be declared in common code.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes#10490
Mark functions used only in the same translation unit as static. This
only includes functions that do not have a prototype in a header file
either.
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Closes#10470
Implement semi-compatible functionality for mode=0 (preallocation)
and mode=FALLOC_FL_KEEP_SIZE (preallocation beyond EOF) for ZPL.
Since ZFS does COW and snapshots, preallocating blocks for a file
cannot guarantee that writes to the file will not run out of space.
Even if the first overwrite was guaranteed, it would not handle any
later overwrite of blocks due to COW, so strict compliance is futile.
Instead, make a best-effort check that at least enough free space is
currently available in the pool (with a bit of margin), then create
a sparse file of the requested size and continue on with life.
This does not handle all cases (e.g. several fallocate() calls before
writing into the files when the filesystem is nearly full), which
would require a more complex mechanism to be implemented, probably
based on a modified version of dmu_prealloc(), but is usable as-is.
A new module option zfs_fallocate_reserve_percent is used to control
the reserve margin for any single fallocate call. By default, this
is 110% of the requested preallocation size, so an additional 10% of
available space is reserved for overhead to allow the application a
good chance of finishing the write when the fallocate() succeeds.
If the heuristics of this basic fallocate implementation are not
desirable, the old non-functional behavior of returning EOPNOTSUPP
for calls can be restored by setting zfs_fallocate_reserve_percent=0.
The parameter of zfs_statvfs() is changed to take an inode instead
of a dentry, since no dentry is available in zfs_fallocate_common().
A few tests from @behlendorf cover basic fallocate functionality.
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Arshad Hussain <arshad.super@gmail.com>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Issue #326Closes#10408
