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authorEric Biggers <ebiggers@google.com>2022-08-27 09:58:46 +0300
committerEric Biggers <ebiggers@google.com>2022-09-12 03:47:12 +0300
commit53dd3f802a6e269868cb599609287a841e65a996 (patch)
tree78c146e44cc1b8328579a1d939fb3053ebb4d510 /fs
parent2d985f8c6b91b5007a16e640bb9c038c5fb2839b (diff)
downloadlinux-53dd3f802a6e269868cb599609287a841e65a996.tar.xz
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
Diffstat (limited to 'fs')
-rw-r--r--fs/crypto/inline_crypt.c49
-rw-r--r--fs/ext4/file.c9
-rw-r--r--fs/f2fs/f2fs.h2
3 files changed, 32 insertions, 28 deletions
diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
index 90f3e68f166e..8d4bee5bccbf 100644
--- a/fs/crypto/inline_crypt.c
+++ b/fs/crypto/inline_crypt.c
@@ -401,46 +401,45 @@ bool fscrypt_mergeable_bio_bh(struct bio *bio,
EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh);
/**
- * fscrypt_dio_supported() - check whether a DIO (direct I/O) request is
- * supported as far as encryption is concerned
- * @iocb: the file and position the I/O is targeting
- * @iter: the I/O data segment(s)
+ * fscrypt_dio_supported() - check whether DIO (direct I/O) is supported on an
+ * inode, as far as encryption is concerned
+ * @inode: the inode in question
*
* Return: %true if there are no encryption constraints that prevent DIO from
* being supported; %false if DIO is unsupported. (Note that in the
* %true case, the filesystem might have other, non-encryption-related
- * constraints that prevent DIO from actually being supported.)
+ * constraints that prevent DIO from actually being supported. Also, on
+ * encrypted files the filesystem is still responsible for only allowing
+ * DIO when requests are filesystem-block-aligned.)
*/
-bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter)
+bool fscrypt_dio_supported(struct inode *inode)
{
- const struct inode *inode = file_inode(iocb->ki_filp);
- const unsigned int blocksize = i_blocksize(inode);
+ int err;
/* If the file is unencrypted, no veto from us. */
if (!fscrypt_needs_contents_encryption(inode))
return true;
- /* We only support DIO with inline crypto, not fs-layer crypto. */
- if (!fscrypt_inode_uses_inline_crypto(inode))
- return false;
-
/*
- * Since the granularity of encryption is filesystem blocks, the file
- * position and total I/O length must be aligned to the filesystem block
- * size -- not just to the block device's logical block size as is
- * traditionally the case for DIO on many filesystems.
+ * We only support DIO with inline crypto, not fs-layer crypto.
*
- * We require that the user-provided memory buffers be filesystem block
- * aligned too. It is simpler to have a single alignment value required
- * for all properties of the I/O, as is normally the case for DIO.
- * Also, allowing less aligned buffers would imply that data units could
- * cross bvecs, which would greatly complicate the I/O stack, which
- * assumes that bios can be split at any bvec boundary.
+ * To determine whether the inode is using inline crypto, we have to set
+ * up the key if it wasn't already done. This is because in the current
+ * design of fscrypt, the decision of whether to use inline crypto or
+ * not isn't made until the inode's encryption key is being set up. In
+ * the DIO read/write case, the key will always be set up already, since
+ * the file will be open. But in the case of statx(), the key might not
+ * be set up yet, as the file might not have been opened yet.
*/
- if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize))
+ err = fscrypt_require_key(inode);
+ if (err) {
+ /*
+ * Key unavailable or couldn't be set up. This edge case isn't
+ * worth worrying about; just report that DIO is unsupported.
+ */
return false;
-
- return true;
+ }
+ return fscrypt_inode_uses_inline_crypto(inode);
}
EXPORT_SYMBOL_GPL(fscrypt_dio_supported);
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 109d07629f81..26d742620897 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -40,8 +40,13 @@ static bool ext4_dio_supported(struct kiocb *iocb, struct iov_iter *iter)
{
struct inode *inode = file_inode(iocb->ki_filp);
- if (!fscrypt_dio_supported(iocb, iter))
- return false;
+ if (IS_ENCRYPTED(inode)) {
+ if (!fscrypt_dio_supported(inode))
+ return false;
+ if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter),
+ i_blocksize(inode)))
+ return false;
+ }
if (fsverity_active(inode))
return false;
if (ext4_should_journal_data(inode))
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 3c7cdb70fe2e..0759da1919f4 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -4498,7 +4498,7 @@ static inline bool f2fs_force_buffered_io(struct inode *inode,
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
int rw = iov_iter_rw(iter);
- if (!fscrypt_dio_supported(iocb, iter))
+ if (!fscrypt_dio_supported(inode))
return true;
if (fsverity_active(inode))
return true;