qemu-kvm/SOURCES/kvm-file-posix-probe-discard-alignment-on-Linux-block-de.patch

132 lines
3.9 KiB
Diff

From 821ddc7a25a4463f3d9f32c7ae2190f56d597c1b Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 17 Apr 2025 11:05:27 -0400
Subject: [PATCH 1/3] file-posix: probe discard alignment on Linux block
devices
RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
RH-MergeRequest: 450: file-posix: probe discard alignment on Linux block devices
RH-Jira: RHEL-87734
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Eric Blake <eblake@redhat.com>
RH-Commit: [1/3] 89037a51ad7f2d9344e506679c1300b7d4f805ab
Populate the pdiscard_alignment block limit so the block layer is able
align discard requests correctly.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250417150528.76470-2-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit f605796aae42885034400c83ed6a9b07cd6d6481)
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
block/file-posix.c | 67 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 66 insertions(+), 1 deletion(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index ff928b5e85..3d5b024459 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1268,10 +1268,10 @@ static int get_sysfs_zoned_model(struct stat *st, BlockZoneModel *zoned)
}
#endif /* defined(CONFIG_BLKZONED) */
+#ifdef CONFIG_LINUX
/*
* Get a sysfs attribute value as a long integer.
*/
-#ifdef CONFIG_LINUX
static long get_sysfs_long_val(struct stat *st, const char *attribute)
{
g_autofree char *str = NULL;
@@ -1291,6 +1291,30 @@ static long get_sysfs_long_val(struct stat *st, const char *attribute)
}
return ret;
}
+
+/*
+ * Get a sysfs attribute value as a uint32_t.
+ */
+static int get_sysfs_u32_val(struct stat *st, const char *attribute,
+ uint32_t *u32)
+{
+ g_autofree char *str = NULL;
+ const char *end;
+ unsigned int val;
+ int ret;
+
+ ret = get_sysfs_str_val(st, attribute, &str);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* The file is ended with '\n', pass 'end' to accept that. */
+ ret = qemu_strtoui(str, &end, 10, &val);
+ if (ret == 0 && end && *end == '\0') {
+ *u32 = val;
+ }
+ return ret;
+}
#endif
static int hdev_get_max_segments(int fd, struct stat *st)
@@ -1310,6 +1334,23 @@ static int hdev_get_max_segments(int fd, struct stat *st)
#endif
}
+/*
+ * Fills in *dalign with the discard alignment and returns 0 on success,
+ * -errno otherwise.
+ */
+static int hdev_get_pdiscard_alignment(struct stat *st, uint32_t *dalign)
+{
+#ifdef CONFIG_LINUX
+ /*
+ * Note that Linux "discard_granularity" is QEMU "discard_alignment". Linux
+ * "discard_alignment" is something else.
+ */
+ return get_sysfs_u32_val(st, "discard_granularity", dalign);
+#else
+ return -ENOTSUP;
+#endif
+}
+
#if defined(CONFIG_BLKZONED)
/*
* If the reset_all flag is true, then the wps of zone whose state is
@@ -1519,6 +1560,30 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
}
}
+ if (S_ISBLK(st.st_mode)) {
+ uint32_t dalign = 0;
+ int ret;
+
+ ret = hdev_get_pdiscard_alignment(&st, &dalign);
+ if (ret == 0) {
+ uint32_t ralign = bs->bl.request_alignment;
+
+ /* Probably never happens, but handle it just in case */
+ if (dalign < ralign && (ralign % dalign == 0)) {
+ dalign = ralign;
+ }
+
+ /* The block layer requires a multiple of request_alignment */
+ if (dalign % ralign != 0) {
+ error_setg(errp, "Invalid pdiscard_alignment limit %u is not a "
+ "multiple of request_alignment %u", dalign, ralign);
+ return;
+ }
+
+ bs->bl.pdiscard_alignment = dalign;
+ }
+ }
+
raw_refresh_zoned_limits(bs, &st, errp);
}
--
2.48.1