this broke with 2.2.7, and can potentially cause data loss or inconsistency. the patch basically reverts to pre-2.2.7 behaviour, verified via a fio benchmark.
reported on our forum: https://forum.proxmox.com/threads/163066 upstream PR: https://github.com/openzfs/zfs/pull/17131 Signed-off-by: Fabian Grünbichler <f.gruenbich...@proxmox.com> --- module only change, needs kernel bump to be active ...vols-correctly-detect-flush-requests.patch | 58 +++++++++++++++++++ debian/patches/series | 1 + 2 files changed, 59 insertions(+) create mode 100644 debian/patches/0012-linux-zvols-correctly-detect-flush-requests.patch diff --git a/debian/patches/0012-linux-zvols-correctly-detect-flush-requests.patch b/debian/patches/0012-linux-zvols-correctly-detect-flush-requests.patch new file mode 100644 index 0000000..609934a --- /dev/null +++ b/debian/patches/0012-linux-zvols-correctly-detect-flush-requests.patch @@ -0,0 +1,58 @@ +From c9ae14e064f961709557fdcbdb40e692a97225ec Mon Sep 17 00:00:00 2001 +From: =?UTF-8?q?Fabian=20Gr=C3=BCnbichler?= <f.gruenbich...@proxmox.com> +Date: Mon, 10 Mar 2025 15:51:09 +0100 +Subject: [PATCH] linux: zvols: correctly detect flush requests +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +since 4.10, bio->bi_opf needs to be checked to determine all kinds of +flush requests. this was the case prior to the commit referenced below, +but the order of ifdefs was not the usual one (newest up top), which +might have caused this to slip through. + +this fixes a regression when using zvols as Qemu block devices, but +might have broken other use cases as well. the symptoms are that all +sync writes from within a VM configured to use such a virtual block +devices are ignored and treated as async writes by the host ZFS layer. + +this can be verified using fio in sync mode inside the VM, for example +with + + fio \ + --filename=/dev/sda --ioengine=libaio --loops=1 --size=10G \ + --time_based --runtime=60 --group_reporting --stonewall --name=cc1 \ + --description="CC1" --rw=write --bs=4k --direct=1 --iodepth=1 \ + --numjobs=1 --sync=1 + +which shows an IOPS number way above what the physical device underneath +supports, with "zpool iostat -r 1" on the hypervisor side showing no +sync IO occuring during the benchmark. + +with the regression fixed, both fio inside the VM and the IO stats on +the host show the expected numbers. + +Fixes: 846b5985192467acabf5484ae610b4b37b7f8162 +"config: remove HAVE_REQ_OP_* and HAVE_REQ_*" + +Signed-off-by: Fabian Grünbichler <f.gruenbich...@proxmox.com> +--- + include/os/linux/kernel/linux/blkdev_compat.h | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +diff --git a/include/os/linux/kernel/linux/blkdev_compat.h b/include/os/linux/kernel/linux/blkdev_compat.h +index d96708c60..084869c34 100644 +--- a/include/os/linux/kernel/linux/blkdev_compat.h ++++ b/include/os/linux/kernel/linux/blkdev_compat.h +@@ -383,7 +383,7 @@ bio_set_flush(struct bio *bio) + static inline boolean_t + bio_is_flush(struct bio *bio) + { +- return (bio_op(bio) == REQ_OP_FLUSH); ++ return (bio_op(bio) == REQ_OP_FLUSH) || (op_is_flush(bio->bi_opf)); + } + + /* +-- +2.39.5 + diff --git a/debian/patches/series b/debian/patches/series index 229027f..938488c 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -9,3 +9,4 @@ 0009-arc-stat-summary-guard-access-to-freshly-introduced-.patch 0010-Fix-nfs_truncate_shares-without-etc-exports.d.patch 0011-zpool-status-tighten-bounds-for-noalloc-stat-availab.patch +0012-linux-zvols-correctly-detect-flush-requests.patch -- 2.39.5 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
