Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) What:		/sys/class/bdi/<bdi>/
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) Date:		January 2008
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) Description:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) Provide a place in sysfs for the backing_dev_info object.  This allows
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) setting and retrieving various BDI specific variables.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) The <bdi> identifier can be either of the following:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) MAJOR:MINOR
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) 	Device number for block devices, or value of st_dev on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 	non-block filesystems which provide their own BDI, such as NFS
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 	and FUSE.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) MAJOR:MINOR-fuseblk
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 	Value of st_dev on fuseblk filesystems.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) default
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 	The default backing dev, used for non-block device backed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 	filesystems which do not provide their own BDI.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) Files under /sys/class/bdi/<bdi>/
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) read_ahead_kb (read-write)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 	Size of the read-ahead window in kilobytes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) min_ratio (read-write)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 	Under normal circumstances each device is given a part of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 	total write-back cache that relates to its current average
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 	writeout speed in relation to the other devices.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 	The 'min_ratio' parameter allows assigning a minimum
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 	percentage of the write-back cache to a particular device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 	For example, this is useful for providing a minimum QoS.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) max_ratio (read-write)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 	Allows limiting a particular device to use not more than the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 	given percentage of the write-back cache.  This is useful in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 	situations where we want to avoid one device taking all or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 	most of the write-back cache.  For example in case of an NFS
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 	mount that is prone to get stuck, or a FUSE mount which cannot
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	be trusted to play fair.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) stable_pages_required (read-only)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 	If set, the backing device requires that all pages comprising a write
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 	request must not be changed until writeout is complete.