Merge tag 'block-2023-01-06' of git://git.kernel.dk/linux

Pull block fixes from Jens Axboe:
 "The big change here is obviously the revert of the pktcdvd driver
  removal. Outside of that, just minor tweaks. In detail:

   - Re-instate the pktcdvd driver, which necessitates adding back
     bio_copy_data_iter() and the fops->devnode() hook for now (me)

   - Fix for splitting of a bio marked as NOWAIT, causing either nowait
     reads or writes to error with EAGAIN even if parts of the IO
     completed (me)

   - Fix for ublk, punting management commands to io-wq as they can all
     easily block for extended periods of time (Ming)

   - Removal of SRCU dependency for the block layer (Paul)"

* tag 'block-2023-01-06' of git://git.kernel.dk/linux:
  block: Remove "select SRCU"
  Revert "pktcdvd: remove driver."
  Revert "block: remove devnode callback from struct block_device_operations"
  Revert "block: bio_copy_data_iter"
  ublk: honor IO_URING_F_NONBLOCK for handling control command
  block: don't allow splitting of a REQ_NOWAIT bio
  block: handle bio_split_to_limits() NULL return

2 files changed, 115 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/debugfs-pktcdvd b/Documentation/ABI/testing/debugfs-pktcdvd
new file mode 100644
index 000000000000..f6f65a4faea0
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-pktcdvd
@@ -0,0 +1,18 @@
+What:           /sys/kernel/debug/pktcdvd/pktcdvd[0-7]
+Date:           Oct. 2006
+KernelVersion:  2.6.20
+Contact:        Thomas Maier <balagi@justmail.de>
+Description:
+
+The pktcdvd module (packet writing driver) creates
+these files in debugfs:
+
+/sys/kernel/debug/pktcdvd/pktcdvd[0-7]/
+
+    ====            ====== ====================================
+    info            0444   Lots of driver statistics and infos.
+    ====            ====== ====================================
+
+Example::
+
+    cat /sys/kernel/debug/pktcdvd/pktcdvd0/info
diff --git a/Documentation/ABI/testing/sysfs-class-pktcdvd b/Documentation/ABI/testing/sysfs-class-pktcdvd
new file mode 100644
index 000000000000..ba1ce626591d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-pktcdvd
@@ -0,0 +1,97 @@
+sysfs interface
+---------------
+The pktcdvd module (packet writing driver) creates the following files in the
+sysfs: (<devid> is in the format major:minor)
+
+What:		/sys/class/pktcdvd/add
+What:		/sys/class/pktcdvd/remove
+What:		/sys/class/pktcdvd/device_map
+Date:		Oct. 2006
+KernelVersion:	2.6.20
+Contact:	Thomas Maier <balagi@justmail.de>
+Description:
+
+		==========	==============================================
+		add		(WO) Write a block device id (major:minor) to
+				create a new pktcdvd device and map it to the
+				block device.
+
+		remove		(WO) Write the pktcdvd device id (major:minor)
+				to remove the pktcdvd device.
+
+		device_map	(RO) Shows the device mapping in format:
+				pktcdvd[0-7] <pktdevid> <blkdevid>
+		==========	==============================================
+
+
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/dev
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/uevent
+Date:		Oct. 2006
+KernelVersion:	2.6.20
+Contact:	Thomas Maier <balagi@justmail.de>
+Description:
+		dev:	(RO) Device id
+
+		uevent:	(WO) To send a uevent
+
+
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
+Date:		Oct. 2006
+KernelVersion:	2.6.20
+Contact:	Thomas Maier <balagi@justmail.de>
+Description:
+		packets_started:	(RO) Number of started packets.
+
+		packets_finished:	(RO) Number of finished packets.
+
+		kb_written:		(RO) kBytes written.
+
+		kb_read:		(RO) kBytes read.
+
+		kb_read_gather:		(RO) kBytes read to fill write packets.
+
+		reset:			(WO) Write any value to it to reset
+					pktcdvd device statistic values, like
+					bytes read/written.
+
+
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
+Date:		Oct. 2006
+KernelVersion:	2.6.20
+Contact:	Thomas Maier <balagi@justmail.de>
+Description:
+		==============	================================================
+		size		(RO) Contains the size of the bio write queue.
+
+		congestion_off	(RW) If bio write queue size is below this mark,
+				accept new bio requests from the block layer.
+
+		congestion_on	(RW) If bio write queue size is higher as this
+				mark, do no longer accept bio write requests
+				from the block layer and wait till the pktcdvd
+				device has processed enough bio's so that bio
+				write queue size is below congestion off mark.
+				A value of <= 0 disables congestion control.
+		==============	================================================
+
+
+Example:
+--------
+To use the pktcdvd sysfs interface directly, you can do::
+
+    # create a new pktcdvd device mapped to /dev/hdc
+    echo "22:0" >/sys/class/pktcdvd/add
+    cat /sys/class/pktcdvd/device_map
+    # assuming device pktcdvd0 was created, look at stat's
+    cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
+    # print the device id of the mapped block device
+    fgrep pktcdvd0 /sys/class/pktcdvd/device_map
+    # remove device, using pktcdvd0 device id   253:0
+    echo "253:0" >/sys/class/pktcdvd/remove