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FROMLIST: fscrypt: Add functions for direct I/O support

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Introduce fscrypt_dio_supported() to check whether a direct I/O request
is unsupported due to encryption constraints.

Also introduce fscrypt_limit_io_blocks() to limit how many blocks can be
added to a bio being prepared for direct I/O. This is needed for
filesystems that use the iomap direct I/O implementation to avoid DUN
wraparound in the middle of a bio (which is possible with the
IV_INO_LBLK_32 IV generation method). Elsewhere fscrypt_mergeable_bio()
is used for this, but iomap operates on logical ranges directly, so
filesystems using iomap won't have a chance to call fscrypt_mergeable_bio()
on every block added to a bio. So we need this function which limits a
logical range in one go.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Co-developed-by: Satya Tangirala <satyat@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>

Bug: 162255927
Link: https://lore.kernel.org/r/20200724184501.1651378-2-satyat@google.com
Change-Id: I1dbd4f382d510d9b779d5e44a77fadf7040cf077
Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Eric Biggers
2020-07-24 18:44:55 +00:00
committed by Satya Tangirala
parent d44ddbf417
commit c7615ef12b
3 changed files with 100 additions and 0 deletions
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18
include/linux/fscrypt.h
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@@ -609,6 +609,10 @@ 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)
@@ -637,6 +641,20 @@ 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 */
#if IS_ENABLED(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_DM_DEFAULT_KEY)