mirror_zfs/include
Rob N 72e4996a54 bdev_discard_supported: understand discard_granularity=0
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.
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
(cherry picked from commit b181b2e604)
2024-04-19 10:19:53 -07:00
..
os bdev_discard_supported: understand discard_granularity=0 2024-04-19 10:19:53 -07:00
sys L2ARC: Relax locking during write 2024-04-19 10:13:38 -07:00
.gitignore OpenZFS restructuring - move platform specific sources 2019-09-06 11:26:26 -07:00
cityhash.h libzfs: convert to -fvisibility=hidden 2021-06-03 13:17:55 -07:00
libnvpair.h nvpair: Constify string functions 2023-03-14 15:25:50 -07:00
libuutil_common.h Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
libuutil_impl.h libuutil: deobfuscate internal pointers 2022-11-03 09:57:05 -07:00
libuutil.h Cleanup: Remove unused uu_pname code 2022-09-19 17:33:52 -07:00
libzfs_core.h Teach zpool scrub to scrub only blocks in error log 2023-05-18 11:59:42 -07:00
libzfs.h zpool: Add slot power control, print power status 2024-01-29 15:12:06 -08:00
libzfsbootenv.h lib{efi,avl,share,tpool,zfs_core,zfsbootenv,zutil}: -fvisibility=hidden 2021-06-09 17:04:32 -07:00
libzutil.h zpool: Add slot power control, print power status 2024-01-29 15:12:06 -08:00
Makefile.am brt: lift internal definitions into _impl header 2023-11-28 12:56:43 -08:00
thread_pool.h Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zfeature_common.h Create zap for root vdev 2023-04-20 10:07:56 -07:00
zfs_comutil.h Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zfs_deleg.h Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zfs_fletcher.h Drop lying to the compiler in the fletcher4 code 2023-03-24 10:29:19 -07:00
zfs_namecheck.h Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zfs_prop.h Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00