From a34d4ef82c3c4bd8bda817e9fb53ef37c5595ddd Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 15 Jun 2023 08:48:39 +0200 Subject: [PATCH] md: make bitmap file support optional The support for write intent bitmaps in files on an external files in md is a hot mess that abuses ->bmap to map file offsets into physical device objects, and also abuses buffer_heads in a creative way. Make this code optional so that MD can be built into future kernels without buffer_head support, and so that we can eventually deprecate it. Note this does not affect the internal bitmap support, which has none of the problems. Signed-off-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: Himanshu Madhani Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230615064840.629492-11-hch@lst.de --- drivers/md/Kconfig | 10 ++++++++++ drivers/md/md-bitmap.c | 15 +++++++++++++++ drivers/md/md.c | 7 +++++++ 3 files changed, 32 insertions(+) diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index b0a22e9..9712ab9 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -50,6 +50,16 @@ config MD_AUTODETECT If unsure, say Y. +config MD_BITMAP_FILE + bool "MD bitmap file support" + default y + help + If you say Y here, support for write intent bitmaps in files on an + external file system is enabled. This is an alternative to the internal + bitmaps near the MD superblock, and very problematic code that abuses + various kernel APIs and can only work with files on a file system not + actually sitting on the MD device. + config MD_LINEAR tristate "Linear (append) mode (deprecated)" depends on BLK_DEV_MD diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index a280bfd..a58a4c3 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -295,6 +295,7 @@ static void write_sb_page(struct bitmap *bitmap, unsigned long pg_index, static void md_bitmap_file_kick(struct bitmap *bitmap); +#ifdef CONFIG_MD_BITMAP_FILE static void write_file_page(struct bitmap *bitmap, struct page *page, int wait) { struct buffer_head *bh = page_buffers(page); @@ -408,6 +409,20 @@ out: ret); return ret; } +#else /* CONFIG_MD_BITMAP_FILE */ +static void write_file_page(struct bitmap *bitmap, struct page *page, int wait) +{ +} +static int read_file_page(struct file *file, unsigned long index, + struct bitmap *bitmap, unsigned long count, struct page *page) +{ + return -EIO; +} +static void free_buffers(struct page *page) +{ + put_page(page); +} +#endif /* CONFIG_MD_BITMAP_FILE */ /* * bitmap file superblock operations diff --git a/drivers/md/md.c b/drivers/md/md.c index 320d715..f46996a 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7043,6 +7043,13 @@ static int set_bitmap_file(struct mddev *mddev, int fd) if (mddev->bitmap || mddev->bitmap_info.file) return -EEXIST; /* cannot add when bitmap is present */ + + if (!IS_ENABLED(CONFIG_MD_BITMAP_FILE)) { + pr_warn("%s: bitmap files not supported by this kernel\n", + mdname(mddev)); + return -EINVAL; + } + f = fget(fd); if (f == NULL) { -- 2.7.4