From: Satya Tangirala <satyat@google.com> To: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-ext4@vger.kernel.org Cc: linux-xfs@vger.kernel.org, Satya Tangirala <satyat@google.com>, Eric Biggers <ebiggers@google.com>, Jaegeuk Kim <jaegeuk@kernel.org> Subject: [PATCH v6 7/7] fscrypt: update documentation for direct I/O support Date: Fri, 24 Jul 2020 18:45:01 +0000 [thread overview] Message-ID: <20200724184501.1651378-8-satyat@google.com> (raw) In-Reply-To: <20200724184501.1651378-1-satyat@google.com> Update fscrypt documentation to reflect the addition of direct I/O support and document the necessary conditions for direct I/O on encrypted files. Signed-off-by: Satya Tangirala <satyat@google.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org> --- Documentation/filesystems/fscrypt.rst | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst index 423c5a0daf45..b9bbd6c612ff 100644 --- a/Documentation/filesystems/fscrypt.rst +++ b/Documentation/filesystems/fscrypt.rst @@ -1049,8 +1049,10 @@ astute users may notice some differences in behavior: may be used to overwrite the source files but isn't guaranteed to be effective on all filesystems and storage devices. -- Direct I/O is not supported on encrypted files. Attempts to use - direct I/O on such files will fall back to buffered I/O. +- Direct I/O is supported on encrypted files only under some + circumstances (see `Direct I/O support`_ for details). When these + circumstances are not met, attempts to use direct I/O on encrypted + files will fall back to buffered I/O. - The fallocate operations FALLOC_FL_COLLAPSE_RANGE and FALLOC_FL_INSERT_RANGE are not supported on encrypted files and will @@ -1123,6 +1125,20 @@ It is not currently possible to backup and restore encrypted files without the encryption key. This would require special APIs which have not yet been implemented. +Direct I/O support +================== + +Direct I/O on encrypted files is supported through blk-crypto. In +particular, this means the kernel must have CONFIG_BLK_INLINE_ENCRYPTION +enabled, the filesystem must have had the 'inlinecrypt' mount option +specified, and either hardware inline encryption must be present, or +CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK must have been enabled. Further, +any I/O must be aligned to the filesystem block size (*not* necessarily +the same as the block device's block size) - in particular, any userspace +buffer into which data is read/written from must also be aligned to the +filesystem block size. If any of these conditions isn't met, attempts to do +direct I/O on an encrypted file will fall back to buffered I/O. + Encryption policy enforcement ============================= -- 2.28.0.rc0.142.g3c755180ce-goog
WARNING: multiple messages have this Message-ID (diff)
From: Satya Tangirala via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net> To: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-ext4@vger.kernel.org Cc: linux-xfs@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>, Eric Biggers <ebiggers@google.com>, Satya Tangirala <satyat@google.com> Subject: [f2fs-dev] [PATCH v6 7/7] fscrypt: update documentation for direct I/O support Date: Fri, 24 Jul 2020 18:45:01 +0000 [thread overview] Message-ID: <20200724184501.1651378-8-satyat@google.com> (raw) In-Reply-To: <20200724184501.1651378-1-satyat@google.com> Update fscrypt documentation to reflect the addition of direct I/O support and document the necessary conditions for direct I/O on encrypted files. Signed-off-by: Satya Tangirala <satyat@google.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org> --- Documentation/filesystems/fscrypt.rst | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst index 423c5a0daf45..b9bbd6c612ff 100644 --- a/Documentation/filesystems/fscrypt.rst +++ b/Documentation/filesystems/fscrypt.rst @@ -1049,8 +1049,10 @@ astute users may notice some differences in behavior: may be used to overwrite the source files but isn't guaranteed to be effective on all filesystems and storage devices. -- Direct I/O is not supported on encrypted files. Attempts to use - direct I/O on such files will fall back to buffered I/O. +- Direct I/O is supported on encrypted files only under some + circumstances (see `Direct I/O support`_ for details). When these + circumstances are not met, attempts to use direct I/O on encrypted + files will fall back to buffered I/O. - The fallocate operations FALLOC_FL_COLLAPSE_RANGE and FALLOC_FL_INSERT_RANGE are not supported on encrypted files and will @@ -1123,6 +1125,20 @@ It is not currently possible to backup and restore encrypted files without the encryption key. This would require special APIs which have not yet been implemented. +Direct I/O support +================== + +Direct I/O on encrypted files is supported through blk-crypto. In +particular, this means the kernel must have CONFIG_BLK_INLINE_ENCRYPTION +enabled, the filesystem must have had the 'inlinecrypt' mount option +specified, and either hardware inline encryption must be present, or +CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK must have been enabled. Further, +any I/O must be aligned to the filesystem block size (*not* necessarily +the same as the block device's block size) - in particular, any userspace +buffer into which data is read/written from must also be aligned to the +filesystem block size. If any of these conditions isn't met, attempts to do +direct I/O on an encrypted file will fall back to buffered I/O. + Encryption policy enforcement ============================= -- 2.28.0.rc0.142.g3c755180ce-goog _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
next prev parent reply other threads:[~2020-07-24 18:45 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-24 18:44 [PATCH v6 0/7] add support for direct I/O with fscrypt using blk-crypto Satya Tangirala 2020-07-24 18:44 ` [f2fs-dev] " Satya Tangirala via Linux-f2fs-devel 2020-07-24 18:44 ` [PATCH v6 1/7] fscrypt: Add functions for direct I/O support Satya Tangirala 2020-07-24 18:44 ` [f2fs-dev] " Satya Tangirala via Linux-f2fs-devel 2020-07-25 0:14 ` Dave Chinner 2020-07-25 0:14 ` [f2fs-dev] " Dave Chinner 2020-07-26 2:49 ` Eric Biggers 2020-07-26 2:49 ` Eric Biggers 2020-07-27 0:58 ` Dave Chinner 2020-07-27 0:58 ` Dave Chinner 2020-07-27 2:59 ` Eric Biggers 2020-07-27 2:59 ` [f2fs-dev] " Eric Biggers 2020-07-27 4:47 ` Dave Chinner 2020-07-27 4:47 ` [f2fs-dev] " Dave Chinner 2020-07-24 18:44 ` [PATCH v6 2/7] direct-io: add support for fscrypt using blk-crypto Satya Tangirala 2020-07-24 18:44 ` [f2fs-dev] " Satya Tangirala via Linux-f2fs-devel 2020-07-24 18:44 ` [PATCH v6 3/7] iomap: support direct I/O with " Satya Tangirala 2020-07-24 18:44 ` [f2fs-dev] " Satya Tangirala via Linux-f2fs-devel 2020-07-24 18:44 ` [PATCH v6 4/7] ext4: " Satya Tangirala 2020-07-24 18:44 ` [f2fs-dev] " Satya Tangirala via Linux-f2fs-devel 2020-07-24 18:44 ` [PATCH v6 5/7] f2fs: " Satya Tangirala 2020-07-24 18:44 ` [f2fs-dev] " Satya Tangirala via Linux-f2fs-devel 2020-07-24 18:45 ` [PATCH v6 6/7] fscrypt: document inline encryption support Satya Tangirala 2020-07-24 18:45 ` [f2fs-dev] " Satya Tangirala via Linux-f2fs-devel 2020-07-27 16:43 ` Eric Biggers 2020-07-27 16:43 ` [f2fs-dev] " Eric Biggers 2020-07-24 18:45 ` Satya Tangirala [this message] 2020-07-24 18:45 ` [f2fs-dev] [PATCH v6 7/7] fscrypt: update documentation for direct I/O support Satya Tangirala via Linux-f2fs-devel
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