fscrypt: change fscrypt_dio_supported() to prepare for STATX_DIOALIGN

To prepare for STATX_DIOALIGN support, make two changes to
fscrypt_dio_supported().

First, remove the filesystem-block-alignment check and make the
filesystems handle it instead.  It previously made sense to have it in
fs/crypto/; however, to support STATX_DIOALIGN the alignment restriction
would have to be returned to filesystems.  It ends up being simpler if
filesystems handle this part themselves, especially for f2fs which only
allows fs-block-aligned DIO in the first place.

Second, make fscrypt_dio_supported() work on inodes whose encryption key
hasn't been set up yet, by making it set up the key if needed.  This is
required for statx(), since statx() doesn't require a file descriptor.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220827065851.135710-4-ebiggers@kernel.org

1 files changed, 2 insertions, 5 deletions

diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 7d2f1e0f23b1..13598859d5b3 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -768,7 +768,7 @@ bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
 bool fscrypt_mergeable_bio_bh(struct bio *bio,
 			      const struct buffer_head *next_bh);
 
-bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter);
+bool fscrypt_dio_supported(struct inode *inode);
 
 u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks);
 
@@ -801,11 +801,8 @@ static inline bool fscrypt_mergeable_bio_bh(struct bio *bio,
 	return true;
 }
 
-static inline bool fscrypt_dio_supported(struct kiocb *iocb,
-					 struct iov_iter *iter)
+static inline bool fscrypt_dio_supported(struct inode *inode)
 {
-	const struct inode *inode = file_inode(iocb->ki_filp);
-
 	return !fscrypt_needs_contents_encryption(inode);
 }