torvalds/linux@09022bc196 removes the flag, and the corresponding
SetPageError() and ClearPageError() macros, with no replacement offered.
Going back through the upstream history, use of this flag has been
gradually removed over the last year as part of the long tail of
converting everything to folios. Interesting tidbit comments from
torvalds/linux@29e9412b25 and torvalds/linux@420e05d0de suggest that
this flag has not been used meaningfully since page writeback failures
started being recorded in errseq_t instead (the whole "fsyncgate" thing,
~2017, around torvalds/linux@8ed1e46aaf).
Given that, it's possible that since perhaps Linux 4.13 we haven't been
getting anything by setting the flag. I don't know if that's true and/or
if there's something we should be doing instead, but my gut feel is that
its probably fine we only use the page cache as a proxy to allow mmap()
to work, rather than backing IO with it.
As such, I'm expecting that removing this will do no harm, but I'm
leaving it in for older kernels to maintain status quo, and if there is
an overall better way, that is left for a future change.
Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes#16582
linux/torvalds@11068e0b64 removes it, suggesting this was a always
there as a helper to handle concurrent seeks, which all filesystems now
handle themselves if necessary.
Without looking into the mechanism, I can imagine how it might have been
used, but we have always set it to zero and never read from it,
presumably because we've always tracked per-caller position through the
znode anyway. So I don't see how there can be any functional change for
us by removing it. I've stayed conservative though and left it in for
older kernels, since its clearly not hurting anything there.
Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes#16582
torvalds/linux@641bb4394f asserts that this is a static flag, not
intended to be variable per-file, so it moves it to
file_operations instead. We just change our check to follow.
No configure check is necessary because FOP_UNSIGNED_OFFSET didn't exist
before this commit, and FMODE_UNSIGNED_OFFSET flag is removed in the
same commit, so there's no chance of a conflict.
It's not clear to me that we need this check at all, as we never set
this flag on our own files, and I can't see any way that our llseek
handler could recieve a file from another filesystem. But, the whole
zpl_llseek() has a number of opportunities for pleasing cleanup that are
nothing to do with this change, so I'll leave that for a future change.
Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes#16582
Too many times, people's performance problems have amounted to
"somehow your SIMD support isn't working", and determining that
at runtime is difficult to describe to people.
This adds a /proc/spl/kstat/zfs/simd node, which exposes
metadata about which instructions ZFS thinks it can use,
on AArch64 and x86_64 Linux, to make investigating things
like this much easier.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes#16530
Following 2b069768a (#16479), anything gated on a kernel version before
4.18 can be always included/excluded.
Sponsored-by: https://despairlabs.com/sponsor/
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes#16545
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
Since the change to folios it has just been a wrapper anyway. Linux has
removed their wrapper, so we add one.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/Closes#16400
It's no longer available directly on the request queue, but its easy to
get from the attached disk.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/Closes#16400
In 6.11 struct queue_limits gains a 'features' field, where, among other
things, flush and write-cache are enabled. Detect it and use it.
Along the way, the blk_queue_set_write_cache() compat wrapper gets a
little cleanup. Since both flags are alway set together, its now a
single bool. Also the very very ancient version that sets q->flush_flags
directly couldn't actually turn it off, so I've fixed that. Not that we
use it, but still.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/Closes#16400
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>
If the underlying device doesn't have a write-back cache, the kernel
will just return a successful response. This doesn't hurt anything, but
it's extra work on the IO taskqs that are unnecessary. So, detect this
when we open the device for the first time.
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes#16148
Kernel documentation for the discard_granularity property says:
A discard_granularity of 0 means that the device does not support
discard functionality.
Some older kernels had drivers (notably loop, but also some USB-SATA
adapters) that would set the QUEUE_FLAG_DISCARD capability flag, but
have discard_granularity=0. Since 5.10 (torvalds/linux@b35fd7422c) the
discard entry point blkdev_issue_discard() has had a check for this,
which would immediately reject the call with EOPNOTSUPP, and throw a
scary diagnostic message into the log. See #16068.
Since 6.8, the block layer sets a non-zero default for
discard_granularity (torvalds/linux@3c407dc723), and a future kernel
will remove the check entirely[1].
As such, there's no good reason for us to enable discard when
discard_granularity=0. The kernel will never let the request go in
anyway; better that we just disable it so we can report it properly to
the user.
1. https://patchwork.kernel.org/project/linux-block/patch/20240312144826.1045212-2-hch@lst.de/
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes#16068Closes#16082
