From c6c89783eba05a5e159b07cfd8c68d841cc5de42 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 28 Jan 2022 15:39:36 -0800 Subject: fscrypt: add functions for direct I/O support Encrypted files traditionally haven't supported DIO, due to the need to encrypt/decrypt the data. However, when the encryption is implemented using inline encryption (blk-crypto) instead of the traditional filesystem-layer encryption, it is straightforward to support DIO. In preparation for supporting this, add the following functions: - fscrypt_dio_supported() checks whether a DIO request is supported as far as encryption is concerned. Encrypted files will only support DIO when inline encryption is used and the I/O request is properly aligned; this function checks these preconditions. - fscrypt_limit_io_blocks() limits the length of a bio to avoid crossing a place in the file that a bio with an encryption context cannot cross due to a DUN discontiguity. This function is needed by filesystems that use the iomap DIO implementation (which operates directly on logical ranges, so it won't use fscrypt_mergeable_bio()) and that support FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32. Co-developed-by: Satya Tangirala Signed-off-by: Satya Tangirala Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20220128233940.79464-2-ebiggers@kernel.org Signed-off-by: Eric Biggers --- include/linux/fscrypt.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'include/linux/fscrypt.h') diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 91ea9477e9bd..50d92d805bd8 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -714,6 +714,10 @@ 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); + +u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks); + #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) @@ -742,6 +746,20 @@ 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) +{ + const struct inode *inode = file_inode(iocb->ki_filp); + + return !fscrypt_needs_contents_encryption(inode); +} + +static inline u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, + u64 nr_blocks) +{ + return nr_blocks; +} #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ /** -- cgit v1.2.3