On Jun 14, 2023, at 11:48 PM, Christoph Hellwig [off-list ref] wrote:

The support for bitmaps on files is a very bad idea abusing various kernel
APIs, and fundamentally requires the file to not be on the actual array
without a way to check that this is actually the case.  Add a deprecation
warning to see if we might be able to eventually drop it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/md/Kconfig | 2 +-
drivers/md/md.c    | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 9712ab9bcba52e..444517d1a2336a 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig

@@ -51,7 +51,7 @@ config MD_AUTODETECT
 If unsure, say Y.

config MD_BITMAP_FILE
- bool "MD bitmap file support"
+ bool "MD bitmap file support (deprecated)"
default y
help
 If you say Y here, support for write intent bitmaps in files on an

diff --git a/drivers/md/md.c b/drivers/md/md.c
index c9fcefaf9c073b..d04a91295edf9d 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -7026,6 +7026,8 @@ static int set_bitmap_file(struct mddev *mddev, int fd)

mdname(mddev));
return -EINVAL;
}
+ pr_warn("%s: using deprecated bitmap file support\n",
+ mdname(mddev));

f = fget(fd);

-- 
2.39.2