qemu-kvm/kvm-file-posix-populate-pwrite_zeroes_alignment.patch
2026-08-24 12:40:59 -04:00

66 lines
2.3 KiB
Diff

From 9aa4988b7506ff56f7c02ac0794f29b0766adb6f Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Tue, 7 Oct 2025 10:16:58 -0400
Subject: [PATCH 1/3] file-posix: populate pwrite_zeroes_alignment
RH-Author: Kevin Wolf <kwolf@redhat.com>
RH-MergeRequest: 565: block: Fix image creation on storage with 4k sector size
RH-Jira: RHEL-207389
RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
RH-Acked-by: German Maglione <None>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Commit: [1/3] dd57fecd1f1d62be600451c47efb061925e89154 (kmwolf/rhel-qemu-kvm)
Linux block devices require write zeroes alignment whereas files do not.
It may come as a surprise that block devices opened in buffered I/O mode
require the alignment for write zeroes requests although normal
read/write requests do not.
Therefore it is necessary to populate the pwrite_zeroes_alignment field.
Cc: qemu-stable@nongnu.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20251007141700.71891-2-stefanha@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Tested-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 98e788b91ad037193b1fb375561ef7e0fef3c2fd)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/file-posix.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/block/file-posix.c b/block/file-posix.c
index ffca37130b..0129413273 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1607,6 +1607,22 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
bs->bl.pdiscard_alignment = dalign;
}
+
+#ifdef __linux__
+ /*
+ * Linux requires logical block size alignment for write zeroes even
+ * when normal reads/writes do not require alignment.
+ */
+ if (!s->needs_alignment) {
+ ret = probe_logical_blocksize(s->fd,
+ &bs->bl.pwrite_zeroes_alignment);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret,
+ "Failed to probe logical block size");
+ return;
+ }
+ }
+#endif /* __linux__ */
}
raw_refresh_zoned_limits(bs, &st, errp);
--
2.52.0