From 50b2a4f19b224694e2bc71a98a7a67aeebacc95e Mon Sep 17 00:00:00 2001 From: Baokun Li Date: Mon, 10 Nov 2025 20:47:14 +0800 Subject: [PATCH] bdev: add hint prints in sb_set_blocksize() for LBS dependency on THP Support for block sizes greater than the page size depends on large folios, which in turn require CONFIG_TRANSPARENT_HUGEPAGE to be enabled. Because the code is wrapped in multiple layers of abstraction, this dependency is rather obscure, so users may not realize it and may be unsure how to enable LBS. As suggested by Theodore, I have added hint messages in sb_set_blocksize so that users can distinguish whether a mount failure with block size larger than page size is due to lack of filesystem support or the absence of CONFIG_TRANSPARENT_HUGEPAGE. Suggested-by: Theodore Ts'o Link: https://patch.msgid.link/20251110043226.GD2988753@mit.edu Signed-off-by: Baokun Li Link: https://patch.msgid.link/20251110124714.1329978-1-libaokun@huaweicloud.com Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Signed-off-by: Christian Brauner --- block/bdev.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/block/bdev.c b/block/bdev.c index 810707cca9703..4888831acaf50 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -217,9 +217,26 @@ int set_blocksize(struct file *file, int size) EXPORT_SYMBOL(set_blocksize); +static int sb_validate_large_blocksize(struct super_block *sb, int size) +{ + const char *err_str = NULL; + + if (!(sb->s_type->fs_flags & FS_LBS)) + err_str = "not supported by filesystem"; + else if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) + err_str = "is only supported with CONFIG_TRANSPARENT_HUGEPAGE"; + + if (!err_str) + return 0; + + pr_warn_ratelimited("%s: block size(%d) > page size(%lu) %s\n", + sb->s_type->name, size, PAGE_SIZE, err_str); + return -EINVAL; +} + int sb_set_blocksize(struct super_block *sb, int size) { - if (!(sb->s_type->fs_flags & FS_LBS) && size > PAGE_SIZE) + if (size > PAGE_SIZE && sb_validate_large_blocksize(sb, size)) return 0; if (set_blocksize(sb->s_bdev_file, size)) return 0; -- 2.47.3