On 8/22/19 10:45 PM, Chaitanya Kulkarni wrote: > Hi, > > The core function where we handle the request null_handle_cmd() in the > null_blk does various things based on how null_blk is configured :- > > 1. Handle throttling. > 2. Handle badblocks. > 3. Handle Memory backed device operations. > 4. Handle Zoned Block device operations. > 5. Completion of the requests. > > With all the above functionality present in the one function, > null_handle_cmd() is growing and becoming unreasonably lengthy when > we want to add more features such as new Zone requests which is being > worked on (See [1], [2]). > > This is a cleanup patch-series which refactors the code in the > null_handle_cmd(). We create a clear interface for each of the above > mentioned functionality which leads to having null_handle_cmd() more > clear and easy to manage with future changes. Please have a look at > NVMe PCIe Driver (nvme_queue_rq()) (See [3]) which has a similar code > structure and nicely structured code for doing various things such as > setting up commands, mapping of the block layer requests, mapping > PRPs/SGLs, handling integrity requests and finally submitting the > NVMe Command etc. > > With this patch-series we fix the following issues with the current > code :- > > 1. Get rid of the multiple nesting levels (> 2). > 2. Easy to read, debug and extend the code for specific feature. > 3. Get rid of the various line foldings which are there in the code > due to multiple level of nesting under if conditions. > 4. Precise definition for the null_handle_cmd() and clear error > handling as helpers are responsible for handling errors. > > Regards, > Chaitanya > > [1] https://www.spinics.net/lists/linux-block/msg41884.html > [2] https://www.spinics.net/lists/linux-block/msg41883.html > [3] https://github.com/torvalds/linux/blob/master/drivers/nvme/host/pci.c > > * Changes from V3:- > 1. Rename nullb_handle_cmd_completion () -> nullb_complete_cmd(). > 2. Move null_handle_zoned() to null_blk_zoned.c and adjust rest of the > code in null_blk_zoned.c. > 3. Fixed the bug in null_handle_cmd() for REQ_OP_ZONE_RESET_ALL. > > * Changes from V2:- > 1. Adjust the code to latest upstream code. > > * Changes from V1:- > 1. Move bio vs req code into the callers for the null_handle_cmd() and > add required arguments to simplify the code in the same function. > 2. Get rid of the extra braces for the null_handle_zoned(). > 3. Get rid of the multiple returns style and the goto. > 4. For throttling, code keep the check in the caller. > 5. Add uniform code format for setting the cmd->error in the > null_handle_cmd() and make required code changes so that each > feature specific function will return blk_status_t value. > > Chaitanya Kulkarni (6): > null_blk: move duplicate code to callers > null_blk: create a helper for throttling > null_blk: create a helper for badblocks > null_blk: create a helper for mem-backed ops > null_blk: create a helper for zoned devices > null_blk: create a helper for req completion > > drivers/block/null_blk.h | 13 +-- > drivers/block/null_blk_main.c | 162 +++++++++++++++++---------------- > drivers/block/null_blk_zoned.c | 38 +++++--- > 3 files changed, 115 insertions(+), 98 deletions(-) Applied, thanks. -- Jens Axboe
