On Sunday, August 18, 2019 7:15:42 PM IST Chao Yu wrote: > Hi Chandan, > > On 2019-8-16 14:18, Chandan Rajendra wrote: > > F2FS has a copy of "post read processing" code using which encrypted > > file data is decrypted. This commit replaces it to make use of the > > generic read_callbacks facility. > > I remember that previously Jaegeuk had mentioned f2fs will support compression > later, and it needs to reuse 'post read processing' fwk. > > There is very initial version of compression feature in below link: > > https://git.kernel.org/pub/scm/linux/kernel/git/chao/linux.git/log/?h=compression > > So my concern is how can we uplift the most common parts of this fwk into vfs, > and meanwhile keeping the ability and flexibility when introducing private > feature/step in specified filesytem(now f2fs)? > > According to current f2fs compression's requirement, maybe we can expand to > > - support callback to let filesystem set the function for the flow in > decompression/verity/decryption step. > - support to use individual/common workqueue according the parameter. > > Any thoughts? > Hi, F2FS can be made to use fscrypt's queue for decryption and hence can reuse "read callbacks" code for decrypting data. For decompression, we could have a STEP_MISC where we invoke a FS provided callback function for FS specific post read processing? Something like the following can be implemented in read_callbacks(), case STEP_MISC: if (ctx->enabled_steps & (1 << STEP_MISC)) { /* ctx->fs_misc() must process bio in a workqueue and later invoke read_callbacks() with bio->bi_private's value as an argument. */ ctx->fs_misc(ctx->bio); return; } ctx->cur_step++; The fs_misc() callback can be passed in by the filesystem when invoking read_callbacks_setup_bio(). -- chandan
