On 6/17/24 15:04, Christoph Hellwig wrote: > Move the cache control settings into the queue_limits so that the flags > can be set atomically with the device queue frozen. > > Add new features and flags field for the driver set flags, and internal > (usually sysfs-controlled) flags in the block layer. Note that we'll > eventually remove enough field from queue_limits to bring it back to the > previous size. > > The disable flag is inverted compared to the previous meaning, which > means it now survives a rescan, similar to the max_sectors and > max_discard_sectors user limits. > > The FLUSH and FUA flags are now inherited by blk_stack_limits, which > simplified the code in dm a lot, but also causes a slight behavior > change in that dm-switch and dm-unstripe now advertise a write cache > despite setting num_flush_bios to 0. The I/O path will handle this > gracefully, but as far as I can tell the lack of num_flush_bios > and thus flush support is a pre-existing data integrity bug in those > targets that really needs fixing, after which a non-zero num_flush_bios > should be required in dm for targets that map to underlying devices. > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > Acked-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> [mmc] A few nits below. With these fixed, Reviewed-by: Damien Le Moal <dlemoal@xxxxxxxxxx> > +Implementation details for bio based block drivers > +-------------------------------------------------- > + > +For bio based drivers the REQ_PREFLUSH and REQ_FUA bit are simplify passed on ...bit are simplify... -> ...bits are simply... > +to the driver if the drivers sets the BLK_FEAT_WRITE_CACHE flag and the drivers > +needs to handle them. s/drivers/driver (2 times) > -and the driver must handle write requests that have the REQ_FUA bit set > -in prep_fn/request_fn. If the FUA bit is not natively supported the block > -layer turns it into an empty REQ_OP_FLUSH request after the actual write. > +When the BLK_FEAT_FUA flags is set, the REQ_FUA bit simplify passed on for the s/bit simplify/bit is simply -- Damien Le Moal Western Digital Research
