From 821ddc7a25a4463f3d9f32c7ae2190f56d597c1b Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi 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 RH-MergeRequest: 450: file-posix: probe discard alignment on Linux block devices RH-Jira: RHEL-87734 RH-Acked-by: Kevin Wolf RH-Acked-by: Eric Blake 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 Message-ID: <20250417150528.76470-2-stefanha@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf (cherry picked from commit f605796aae42885034400c83ed6a9b07cd6d6481) Signed-off-by: Stefan Hajnoczi --- 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