On Friday, August 23, 2019 6:55 PM Chandan Rajendra wrote: > This patchset moves the "FS read I/O callbacks" code into a file of its > own (i.e. fs/read_callbacks.c) and modifies the generic > do_mpage_readpge() to make use of the functionality provided. > > "FS read I/O callbacks" code implements the state machine that needs > to be executed after reading data from files that are encrypted and/or > have verity metadata associated with them. > > With these changes in place, the patchset changes Ext4 to use > mpage_readpage[s] instead of its own custom ext4_readpage[s]() > functions. This is done to reduce duplication of code across > filesystems. Also, "FS read I/O callbacks" source files will be built > only if CONFIG_FS_ENCRYPTION is enabled. > > The patchset also modifies fs/buffer.c to get file > encryption/decryption to work with subpage-sized blocks. > > The patches can also be obtained from > https://github.com/chandanr/linux.git at branch subpage-encryption-v5. Ted and Al, Do you have any comments on the patchset? > > Changelog: > V4 -> V5: > 1. Since F2FS uses its own workqueue and also since its > decompression logic isn't an fs independent entity like fscrypt or > fsverity, this patchset drops support for F2FS. > The patchset still helps in removing a copy of > do_mpage_readpage() from Ext4 (i.e. ext4_readpage()) and also > prevents a copy of block_read_full_page() from being added into > Ext4 by adding support to "read callbacks" API invocations into > block_read_full_page(). > > V3 -> V4: > 1. A new buffer_head flag (i.e. BH_Read_Cb) is introduced to reliably > check if a buffer head's content has to be decrypted. > 2. Fix layering violation. Now the code flow for decryption happens as shown below, > FS => read callbacks => fscrypt > 3. Select FS_READ_CALLBACKS from FS specific kconfig file if FS_ENCRYPTION > is enabled. > 4. Make 'struct read_callbacks_ctx' an opaque structure. > 5. Make use of FS' endio function rather than implementing one in read > callbacks. > 6. Make read_callbacks.h self-contained. > 7. Split patchset to separate out ext4 and f2fs changes. > > V2 -> V3: > 1. Split the V2 patch "Consolidate 'read callbacks' into a new file" into > three patches, > - Introduce the read_callbacks functionality. > - Convert encryption to use read_callbacks. > - Remove union from struct fscrypt_context. > 2. fs/Kconfig > Do not explicitly set the default value of 'n' for FS_READ_CALLBACKS. > 3. fs/crypto/Kconfig > Select CONFIG_FS_READ_CALLBACKS only if CONFIG_BLOCK is selected. > 4. Remove verity associated code in read_callbacks code. > 5. Introduce a callback argument to read_callbacks_setup() function > which gets invoked for each page for bio. F2FS uses this to perform > custom operations like decrementing the value of f2fs_sb_info->nr_pages[]. > 6. Encapsulate the details of "read callbacks" (e.g. Usage of "struct > read_callbacks *ctx") within its own functions. When CONFIG_FS_READ_CALLBACKS > is set to 'n', the corresponding stub functions return approriate error > values. > 7. Split fscrypt_decrypt() function into fscrypt_decrypt_bio() and > fscrypt_decrypt_bh(). > 8. Split end_read_callbacks() function into end_read_callbacks_bio() and > end_read_callbacks_bh(). > > V1 -> V2: > 1. Removed the phrase "post_read_process" from file names and > functions. Instead we now use the phrase "read_callbacks" in its > place. > 2. When performing changes associated with (1), the changes made by > the patch "Remove the term 'bio' from post read processing" are > made in the earlier patch "Consolidate 'read callbacks' into a new > file". Hence the patch "Remove the term 'bio' from post read > processing" is removed from the patchset. > > RFC V2 -> V1: > 1. Test and verify FS_CFLG_OWN_PAGES subset of fscrypt_encrypt_page() > code by executing fstests on UBIFS. > 2. Implement F2fs function call back to check if the contents of a > page holding a verity file's data needs to be verified. > > RFC V1 -> RFC V2: > 1. Describe the purpose of "Post processing code" in the cover letter. > 2. Fix build errors when CONFIG_FS_VERITY is enabled. > > Chandan Rajendra (7): > buffer_head: Introduce BH_Read_Cb flag > FS: Introduce read callbacks > fs/mpage.c: Integrate read callbacks > fs/buffer.c: add decryption support via read_callbacks > ext4: Wire up ext4_readpage[s] to use mpage_readpage[s] > ext4: Enable encryption for subpage-sized blocks > fscrypt: remove struct fscrypt_ctx > > Documentation/filesystems/fscrypt.rst | 4 +- > fs/Kconfig | 3 + > fs/Makefile | 1 + > fs/buffer.c | 33 ++- > fs/crypto/bio.c | 18 -- > fs/crypto/crypto.c | 89 +------- > fs/crypto/fscrypt_private.h | 3 - > fs/ext4/Kconfig | 1 + > fs/ext4/Makefile | 2 +- > fs/ext4/inode.c | 5 +- > fs/ext4/readpage.c | 295 -------------------------- > fs/ext4/super.c | 7 - > fs/f2fs/Kconfig | 1 + > fs/mpage.c | 24 ++- > fs/read_callbacks.c | 285 +++++++++++++++++++++++++ > include/linux/buffer_head.h | 2 + > include/linux/fscrypt.h | 32 --- > include/linux/read_callbacks.h | 48 +++++ > 18 files changed, 391 insertions(+), 462 deletions(-) > delete mode 100644 fs/ext4/readpage.c > create mode 100644 fs/read_callbacks.c > create mode 100644 include/linux/read_callbacks.h > > -- chandan
