From 38ea50daa7a447dbcd7031f37a39a1baa163b2ab Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 28 Jan 2022 15:39:38 -0800 Subject: [PATCH] ext4: support direct I/O with fscrypt using blk-crypto 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. Therefore, make ext4 support DIO on files that are using inline encryption. Since ext4 uses iomap for DIO, and fscrypt support was already added to iomap DIO, this just requires two small changes: - Let DIO proceed when supported, by checking fscrypt_dio_supported() instead of assuming that encrypted files never support DIO. - In ext4_iomap_begin(), use fscrypt_limit_io_blocks() to limit the length of the mapping in the rare case where a DUN discontiguity occurs in the middle of an extent. The iomap DIO implementation requires this, since it assumes that it can submit a bio covering (up to) the whole mapping, without checking fscrypt constraints itself. Co-developed-by: Satya Tangirala Signed-off-by: Satya Tangirala Acked-by: Theodore Ts'o Reviewed-by: Jaegeuk Kim Link: https://lore.kernel.org/r/20220128233940.79464-4-ebiggers@kernel.org Signed-off-by: Eric Biggers --- fs/ext4/file.c | 10 ++++++---- fs/ext4/inode.c | 7 +++++++ 2 files changed, 13 insertions(+), 4 deletions(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 8cc11715518a..8bd66cdc41be 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -36,9 +36,11 @@ #include "acl.h" #include "truncate.h" -static bool ext4_dio_supported(struct inode *inode) +static bool ext4_dio_supported(struct kiocb *iocb, struct iov_iter *iter) { - if (IS_ENABLED(CONFIG_FS_ENCRYPTION) && IS_ENCRYPTED(inode)) + struct inode *inode = file_inode(iocb->ki_filp); + + if (!fscrypt_dio_supported(iocb, iter)) return false; if (fsverity_active(inode)) return false; @@ -61,7 +63,7 @@ static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to) inode_lock_shared(inode); } - if (!ext4_dio_supported(inode)) { + if (!ext4_dio_supported(iocb, to)) { inode_unlock_shared(inode); /* * Fallback to buffered I/O if the operation being performed on @@ -509,7 +511,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from) } /* Fallback to buffered I/O if the inode does not support direct I/O. */ - if (!ext4_dio_supported(inode)) { + if (!ext4_dio_supported(iocb, from)) { if (ilock_shared) inode_unlock_shared(inode); else diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 01c9e4f743ba..4cf55ef54193 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3409,6 +3409,13 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, if (ret < 0) return ret; out: + /* + * When inline encryption is enabled, sometimes I/O to an encrypted file + * has to be broken up to guarantee DUN contiguity. Handle this by + * limiting the length of the mapping returned. + */ + map.m_len = fscrypt_limit_io_blocks(inode, map.m_lblk, map.m_len); + ext4_set_iomap(inode, iomap, &map, offset, length, flags); return 0;