On 10/18/24 23:37, Kevin Wolf wrote: > Am 04.10.2024 um 12:41 hat Sam Li geschrieben: >> When the file-posix driver emulates append write, it holds the lock >> whenever accessing wp, which limits the IO queue depth to one. >> >> The write IO flow can be optimized to allow concurrent writes. The lock >> is held in two cases: >> 1. Assumed that the write IO succeeds, update the wp before issuing the >> write. >> 2. If the write IO fails, report that zone and use the reported value >> as the current wp. > > What happens with the concurrent writes that started later and may not > have completed yet? Can we really just reset to the reported value > before all other requests have completed, too?
Yes, because if one write fails, we know that the following writes will fail too as they will not be aligned to the write pointer. These subsequent failed writes will again trigger the report zones and update, but that is fine. All of them have failed and the report will give the same wp again. This is a typical pattern with zoned block device: if one write fails in a zone, the user has to expect failures for all other writes issued to the same zone, do a report zone to get the wp and restart writing from there. -- Damien Le Moal Western Digital Research
