block: change blk_get_meta_cap() stub return -ENOIOCTLCMD

When introduced in commit 9eb22f7fedfc ("fs: add ioctl to query metadata
and protection info capabilities") the stub of blk_get_meta_cap() for
!BLK_DEV_INTEGRITY always returns -EOPNOTSUPP.  The motivation was that
while the command was unsupported in that configuration it was still
recognized.

A later change instead assumed -ENOIOCTLCMD as is required for unknown
ioctl commands per Documentation/driver-api/ioctl.rst. The result being
that on !BLK_DEV_INTEGRITY configs, any ioctl which reaches
blkdev_common_ioctl() will return -EOPNOTSUPP.

Change the stub to return -ENOIOCTLCMD, fixing the issue and better
matching with expectations.

[ The blkdev_common_ioctl() confusion has been fixed, but -ENOIOCTLCMD
  is the right thing to return for unrecognized ioctls, so the patch
  remains the right thing to do.   - Linus ]

Link: https://lore.kernel.org/lkml/CACzX3AsRd__fXb9=CJPTTJC494SDnYAtYrN2=+bZgMCvM6UQDg@mail.gmail.com
Fixes: 42b0ef01e6b5 ("block: fix FS_IOC_GETLBMD_CAP parsing in blkdev_common_ioctl()")
Signed-off-by: Klara Modin <klarasmodin@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/blk-integrity.h b/include/linux/blk-integrity.h
index e04c6e5bf1c68b0befebfaa75d3327ec987cf17f..e67a2b6e8f11107ea0164411950f5bfae03cea25 100644 (file)
--- a/include/linux/blk-integrity.h
+++ b/include/linux/blk-integrity.h
@@ -97,7 +97,7 @@ static inline struct bio_vec rq_integrity_vec(struct request *rq)
 static inline int blk_get_meta_cap(struct block_device *bdev, unsigned int cmd,
                                   struct logical_block_metadata_cap __user *argp)
 {
-       return -EOPNOTSUPP;
+       return -ENOIOCTLCMD;
 }
 static inline int blk_rq_count_integrity_sg(struct request_queue *q,
                                            struct bio *b)