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. 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 -- 2.19.1
