get_user_pages_unlocked() had stabilised by 4.9.
Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes#16479
Adding O_DIRECT support to ZFS to bypass the ARC for writes/reads.
O_DIRECT support in ZFS will always ensure there is coherency between
buffered and O_DIRECT IO requests. This ensures that all IO requests,
whether buffered or direct, will see the same file contents at all
times. Just as in other FS's , O_DIRECT does not imply O_SYNC. While
data is written directly to VDEV disks, metadata will not be synced
until the associated TXG is synced.
For both O_DIRECT read and write request the offset and request sizes,
at a minimum, must be PAGE_SIZE aligned. In the event they are not,
then EINVAL is returned unless the direct property is set to always (see
below).
For O_DIRECT writes:
The request also must be block aligned (recordsize) or the write
request will take the normal (buffered) write path. In the event that
request is block aligned and a cached copy of the buffer in the ARC,
then it will be discarded from the ARC forcing all further reads to
retrieve the data from disk.
For O_DIRECT reads:
The only alignment restrictions are PAGE_SIZE alignment. In the event
that the requested data is in buffered (in the ARC) it will just be
copied from the ARC into the user buffer.
For both O_DIRECT writes and reads the O_DIRECT flag will be ignored in
the event that file contents are mmap'ed. In this case, all requests
that are at least PAGE_SIZE aligned will just fall back to the buffered
paths. If the request however is not PAGE_SIZE aligned, EINVAL will
be returned as always regardless if the file's contents are mmap'ed.
Since O_DIRECT writes go through the normal ZIO pipeline, the
following operations are supported just as with normal buffered writes:
Checksum
Compression
Encryption
Erasure Coding
There is one caveat for the data integrity of O_DIRECT writes that is
distinct for each of the OS's supported by ZFS.
FreeBSD - FreeBSD is able to place user pages under write protection so
any data in the user buffers and written directly down to the
VDEV disks is guaranteed to not change. There is no concern
with data integrity and O_DIRECT writes.
Linux - Linux is not able to place anonymous user pages under write
protection. Because of this, if the user decides to manipulate
the page contents while the write operation is occurring, data
integrity can not be guaranteed. However, there is a module
parameter `zfs_vdev_direct_write_verify` that controls the
if a O_DIRECT writes that can occur to a top-level VDEV before
a checksum verify is run before the contents of the I/O buffer
are committed to disk. In the event of a checksum verification
failure the write will return EIO. The number of O_DIRECT write
checksum verification errors can be observed by doing
`zpool status -d`, which will list all verification errors that
have occurred on a top-level VDEV. Along with `zpool status`, a
ZED event will be issues as `dio_verify` when a checksum
verification error occurs.
ZVOLs and dedup is not currently supported with Direct I/O.
A new dataset property `direct` has been added with the following 3
allowable values:
disabled - Accepts O_DIRECT flag, but silently ignores it and treats
the request as a buffered IO request.
standard - Follows the alignment restrictions outlined above for
write/read IO requests when the O_DIRECT flag is used.
always - Treats every write/read IO request as though it passed
O_DIRECT and will do O_DIRECT if the alignment restrictions
are met otherwise will redirect through the ARC. This
property will not allow a request to fail.
There is also a module parameter zfs_dio_enabled that can be used to
force all reads and writes through the ARC. By setting this module
parameter to 0, it mimics as if the direct dataset property is set to
disabled.
Reviewed-by: Brian Behlendorf <behlendorf@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
Co-authored-by: Mark Maybee <mark.maybee@delphix.com>
Co-authored-by: Matt Macy <mmacy@FreeBSD.org>
Co-authored-by: Brian Behlendorf <behlendorf@llnl.gov>
Closes#10018
Changed zfs_k(un)map_atomic to zfs_k(un)map_local
Signed-off-by: Jason Lee <jasonlee@lanl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
This fix removes a dubious optimization in zfs_uiomove_bvec_rq()
that saved the iterator contents of a rq_for_each_segment(). This
optimization allowed restoring the "saved state" from a previous
rq_for_each_segment() call on the same uio so that you wouldn't
need to iterate though each bvec on every zfs_uiomove_bvec_rq() call.
However, if the kernel is manipulating the requests/bios/bvecs under
the covers between zfs_uiomove_bvec_rq() calls, then it could result
in corruption from using the "saved state". This optimization
results in an unbootable system after installing an OS on a zvol
with blk-mq enabled.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes#15351
Add support for the kernel's block multiqueue (blk-mq) interface in
the zvol block driver. blk-mq creates multiple request queues on
different CPUs rather than having a single request queue. This can
improve zvol performance with multithreaded reads/writes.
This implementation uses the blk-mq interfaces on 4.13 or newer
kernels. Building against older kernels will fall back to the
older BIO interfaces.
Note that you must set the `zvol_use_blk_mq` module param to
enable the blk-mq API. It is disabled by default.
In addition, this commit lets the zvol blk-mq layer process whole
`struct request` IOs at a time, rather than breaking them down
into their individual BIOs. This reduces dbuf lock contention
and overhead versus the legacy zvol submit_bio() codepath.
sequential dd to one zvol, 8k volblocksize, no O_DIRECT:
legacy submit_bio() 292MB/s write 453MB/s read
this commit 453MB/s write 885MB/s read
It also introduces a new `zvol_blk_mq_chunks_per_thread` module
parameter. This parameter represents how many volblocksize'd chunks
to process per each zvol thread. It can be used to tune your zvols
for better read vs write performance (higher values favor write,
lower favor read).
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes#13148
Issue #12483
Linux 5.12 PPC 5.12 get_user() and __copy_from_user_inatomic()
inline helpers very indirectly include a reference to the GPL'd
array mmu_feature_keys[] and fails to build. Workaround this by
using copy_from_user() and throwing EFAULT for any calls to
__copy_from_user_inatomic(). This is a workaround until a fix
for Linux commit 7613f5a66becfd0e43a0f34de8518695888f5458
"powerpc/64s/kuap: Use mmu_has_feature()" is fully addressed.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Authored-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: szubersk <szuberskidamian@gmail.com>
Closes#11958Closes#12590Closes#13367
bcopy() has a confusing argument order and is actually a move, not a
copy; they're all deprecated since POSIX.1-2001 and removed in -2008,
and we shim them out to mem*() on Linux anyway
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes#12996
It used to be required to pass a enum km_type to kmap_atomic() and
kunmap_atomic(), however this is no longer necessary and the wrappers
zfs_k(un)map_atomic removed these. This is confusing in the ABD code as
the struct abd_iter member iter_km no longer exists and the wrapper
macros simply compile them out.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Adam Moss <c@yotes.com>
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
Closes#11768
As part of commit 1c2358c1 the custom uio_prefaultpages() code
was removed in favor of using the generic kernel provided
iov_iter_fault_in_readable() interface. Unfortunately, it
turns out that up until the Linux 4.7 kernel the function would
only ever fault in the first iovec of the iov_iter. The result
being uiomove_iov() may hang waiting for the page.
This commit effectively restores the custom uio_prefaultpages()
pages code for Linux 4.9 and earlier kernels which contain the
troublesome version of iov_iter_fault_in_readable().
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#11463Closes#11484
In FreeBSD the struct uio was just a typedef to uio_t. In order to
extend this struct, outside of the definition for the struct uio, the
struct uio has been embedded inside of a uio_t struct.
Also renamed all the uio_* interfaces to be zfs_uio_* to make it clear
this is a ZFS interface.
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
Closes#11438
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();
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
