kernel.git/fs/btrfs/raid56.h, branch linux-6.3.y

btrfs: fix spelling mistakes found using codespell

2023-02-15T18:38:50Z

There quite a few spelling mistakes as found using codespell. Fix them. Signed-off-by: Colin Ian King Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: raid56: prepare data checksums for later RMW verification

2022-12-05T17:00:57Z

This is for later data checksum verification at RMW time. This patch will try to allocate the needed memory for a locked rbio if the rbio is for data exclusively (we don't want to handle mixed bg yet). The memory will be released when the rbio is finished. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: raid56: remove the old error tracking system

2022-12-05T17:00:55Z

Since all the recovery paths have been migrated to the new error bitmap based system, we can remove the old stripe number based system. This cleanup involves one behavior change: - Rebuild rbio can no longer be merged Previously a rebuild rbio (caused by retry after data csum mismatch) can be merged, if the error happens in the same stripe. But with the new error bitmap based solution, it's much harder to compare error bitmaps. So here we just don't merge rebuild rbio at all. This may introduce some performance impact at extreme corner cases, but we're willing to take it. Other than that, this patch will cleanup the following members: - rbio::faila - rbio::failb They will be replaced by per-vertical stripe check, which is more accurate. - rbio::error It will be replace by per-vertical stripe error bitmap check. - Allow get_rbio_vertical_errors() to accept NULL pointers for @faila and @failb Some call sites only want to check if we have errors beyond the tolerance. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: raid56: introduce btrfs_raid_bio::error_bitmap

2022-12-05T17:00:55Z

Currently btrfs raid56 uses btrfs_raid_bio::faila and failb to indicate which stripe(s) had IO errors. But that has some problems: - If one sector failed csum check, the whole stripe where the corruption is will be marked error. This can reduce the chance we do recover, like this: 0 4K 8K Data 1 |XX| | Data 2 | |XX| Parity | | | In above case, 0~4K in data 1 should be recovered using data 2 and parity, while 4K~8K in data 2 should be recovered using data 1 and parity. Currently if we trigger read on 0~4K of data 1, we will also recover 4K~8K of data 1 using corrupted data 2 and parity, causing wrong result in rbio cache. - Harder to expand for future M-N scheme As we're limited to just faila/b, two corruptions. - Harder to expand to handle extra csum errors This can be problematic if we start to do csum verification. This patch will introduce an extra @error_bitmap, where one bit represents error that happened for that sector. The choice to introduce a new error bitmap other than reusing sector_ptr, is to avoid extra search between rbio::stripe_sectors[] and rbio::bio_sectors[]. Since we can submit bio using sectors from both sectors, doing proper search on both array will more complex. Although the new bitmap will take extra memory, later we can remove things like @error and faila/b to save some memory. Currently the new error bitmap and failab mechanism coexists, the error bitmap is only updated at endio time and recover entrance. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: remove the unused endio_raid56_workers and btrfs_raid_bio::end_io_work

2022-12-05T17:00:49Z

Since we have switched all raid56 workload to submit-and-wait method, there is no use for btrfs_fs_info::endio_raid56_workers workqueue and btrfs_raid_bio::end_io_work. Remove them to save some memory. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: raid56: switch write path to rmw_rbio()

2022-12-05T17:00:49Z

This includes the following changes: - Implement new raid_unplug() functions Now we don't need a workqueue to run the plug, as all our work is just queue rmw_rbio_work() call, which can be executed without sleep. - Implement a rmw_rbio_work_locked() helper This is for unlock_stripe(), which is already holding the full stripe lock. - Remove all the old functions This should already shows how complex the old functions are, as we ended up removing the following functions: * rmw_work() * validate_rbio_for_rmw() * raid56_rmw_end_io_work() * raid56_rmw_stripe() * full_stripe_write() * partial_stripe_write() * __raid56_parity_write() * run_plug() * unplug_work() * btrfs_raid_unplug() * rmw_work() * __raid56_parity_recover() * raid_recover_end_io_work() - Unexport rmw_rbio() Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: raid56: introduce the main entrance for RMW path

2022-12-05T17:00:49Z

The new entrance will be called rmw_rbio(), it will have a streamlined workflow by using submit-and-wait method. Thus there will be no weird jumps between tons of functions, thus way more reader friendly, and will make later expansion easier, as it's now a straight workflow, the timing is way more clear. Unfortunately we can not yet migrate the RMW path to use this new entrance as we still need extra work to address the plug and unlock_stripe() function. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: raid56: switch recovery path to a single function

2022-12-05T17:00:49Z

Currently btrfs uses end_io functions to jump between different stages of recovery. For example, we go the following different functions: - raid56_bio_end_io() This handles the read for all the sectors (except the missing device). - __raid_recover_end_io() This does the real work, it's called inside the delayed work function raid_recover_end_io_work(). This one recovery path involves at least 3 different functions, which is a big burden for readers. This patch will change the behavior by: - Introduce a unified recovery entrance, recover_rbio() - Use submit-and-wait method So the workflow is not interrupted by the endio function jump. This doesn't bring performance change, but reduce the burden for reviewers. - Run the main function in the rmw_workers workqueue Now raid56_parity_recover() only needs to setup the work, and queue the work using start_async_work(). Now readers only need to do one function jump (start_async_work()) to find out the main entrance of recovery path. Furthermore, recover_rbio() function can easily be reused by other paths. The old recovery path is still utilized by degraded write path. It will be cleaned up when we have migrated the write path. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: properly abstract the parity raid bio handling

2022-09-26T10:27:59Z

The parity raid write/recover functionality is currently not very well abstracted from the bio submission and completion handling in volumes.c: - the raid56 code directly completes the original btrfs_bio fed into btrfs_submit_bio instead of dispatching back to volumes.c - the raid56 code consumes the bioc and bio_counter references taken by volumes.c, which also leads to special casing of the calls from the scrub code into the raid56 code To fix this up supply a bi_end_io handler that calls back into the volumes.c machinery, which then puts the bioc, decrements the bio_counter and completes the original bio, and updates the scrub code to also take ownership of the bioc and bio_counter in all cases. Reviewed-by: Nikolay Borisov Reviewed-by: Anand Jain Tested-by: Nikolay Borisov Tested-by: Johannes Thumshirn Signed-off-by: Christoph Hellwig Signed-off-by: David Sterba

btrfs: do not return errors from raid56_parity_recover

2022-07-25T15:45:39Z

Always consume the bio and call the end_io handler on error instead of returning an error and letting the caller handle it. This matches what the block layer submission does and avoids any confusion on who needs to handle errors. Also use the proper bool type for the generic_io argument. Reviewed-by: Nikolay Borisov Tested-by: Nikolay Borisov Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Signed-off-by: Christoph Hellwig Signed-off-by: David Sterba