Merge tag 'for-6.16/block-20250523' of git://git.kernel.dk/linux

Pull block updates from Jens Axboe:

 - ublk updates:
      - Add support for updating the size of a ublk instance
      - Zero-copy improvements
      - Auto-registering of buffers for zero-copy
      - Series simplifying and improving GET_DATA and request lookup
      - Series adding quiesce support
      - Lots of selftests additions
      - Various cleanups

 - NVMe updates via Christoph:
      - add per-node DMA pools and use them for PRP/SGL allocations
        (Caleb Sander Mateos, Keith Busch)
      - nvme-fcloop refcounting fixes (Daniel Wagner)
      - support delayed removal of the multipath node and optionally
        support the multipath node for private namespaces (Nilay Shroff)
      - support shared CQs in the PCI endpoint target code (Wilfred
        Mallawa)
      - support admin-queue only authentication (Hannes Reinecke)
      - use the crc32c library instead of the crypto API (Eric Biggers)
      - misc cleanups (Christoph Hellwig, Marcelo Moreira, Hannes
        Reinecke, Leon Romanovsky, Gustavo A. R. Silva)

 - MD updates via Yu:
      - Fix that normal IO can be starved by sync IO, found by mkfs on
        newly created large raid5, with some clean up patches for bdev
        inflight counters

 - Clean up brd, getting rid of atomic kmaps and bvec poking

 - Add loop driver specifically for zoned IO testing

 - Eliminate blk-rq-qos calls with a static key, if not enabled

 - Improve hctx locking for when a plug has IO for multiple queues
   pending

 - Remove block layer bouncing support, which in turn means we can
   remove the per-node bounce stat as well

 - Improve blk-throttle support

 - Improve delay support for blk-throttle

 - Improve brd discard support

 - Unify IO scheduler switching. This should also fix a bunch of lockdep
   warnings we've been seeing, after enabling lockdep support for queue
   freezing/unfreezeing

 - Add support for block write streams via FDP (flexible data placement)
   on NVMe

 - Add a bunch of block helpers, facilitating the removal of a bunch of
   duplicated boilerplate code

 - Remove obsolete BLK_MQ pci and virtio Kconfig options

 - Add atomic/untorn write support to blktrace

 - Various little cleanups and fixes

* tag 'for-6.16/block-20250523' of git://git.kernel.dk/linux: (186 commits)
  selftests: ublk: add test for UBLK_F_QUIESCE
  ublk: add feature UBLK_F_QUIESCE
  selftests: ublk: add test case for UBLK_U_CMD_UPDATE_SIZE
  traceevent/block: Add REQ_ATOMIC flag to block trace events
  ublk: run auto buf unregisgering in same io_ring_ctx with registering
  io_uring: add helper io_uring_cmd_ctx_handle()
  ublk: remove io argument from ublk_auto_buf_reg_fallback()
  ublk: handle ublk_set_auto_buf_reg() failure correctly in ublk_fetch()
  selftests: ublk: add test for covering UBLK_AUTO_BUF_REG_FALLBACK
  selftests: ublk: support UBLK_F_AUTO_BUF_REG
  ublk: support UBLK_AUTO_BUF_REG_FALLBACK
  ublk: register buffer to local io_uring with provided buf index via UBLK_F_AUTO_BUF_REG
  ublk: prepare for supporting to register request buffer automatically
  ublk: convert to refcount_t
  selftests: ublk: make IO & device removal test more stressful
  nvme: rename nvme_mpath_shutdown_disk to nvme_mpath_remove_disk
  nvme: introduce multipath_always_on module param
  nvme-multipath: introduce delayed removal of the multipath head node
  nvme-pci: derive and better document max segments limits
  nvme-pci: use struct_size for allocation struct nvme_dev
  ...

2 files changed, 170 insertions, 0 deletions

diff --git a/Documentation/admin-guide/blockdev/index.rst b/Documentation/admin-guide/blockdev/index.rst
index 957ccf617797..3262397ebe8f 100644
--- a/Documentation/admin-guide/blockdev/index.rst
+++ b/Documentation/admin-guide/blockdev/index.rst
@@ -11,6 +11,7 @@ Block Devices
    nbd
    paride
    ramdisk
+   zoned_loop
    zram
 
    drbd/index
diff --git a/Documentation/admin-guide/blockdev/zoned_loop.rst b/Documentation/admin-guide/blockdev/zoned_loop.rst
new file mode 100644
index 000000000000..9c7aa3b482f3
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/zoned_loop.rst
@@ -0,0 +1,169 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================
+Zoned Loop Block Device
+=======================
+
+.. Contents:
+
+	1) Overview
+	2) Creating a Zoned Device
+	3) Deleting a Zoned Device
+	4) Example
+
+
+1) Overview
+-----------
+
+The zoned loop block device driver (zloop) allows a user to create a zoned block
+device using one regular file per zone as backing storage. This driver does not
+directly control any hardware and uses read, write and truncate operations to
+regular files of a file system to emulate a zoned block device.
+
+Using zloop, zoned block devices with a configurable capacity, zone size and
+number of conventional zones can be created. The storage for each zone of the
+device is implemented using a regular file with a maximum size equal to the zone
+size. The size of a file backing a conventional zone is always equal to the zone
+size. The size of a file backing a sequential zone indicates the amount of data
+sequentially written to the file, that is, the size of the file directly
+indicates the position of the write pointer of the zone.
+
+When resetting a sequential zone, its backing file size is truncated to zero.
+Conversely, for a zone finish operation, the backing file is truncated to the
+zone size. With this, the maximum capacity of a zloop zoned block device created
+can be larger configured to be larger than the storage space available on the
+backing file system. Of course, for such configuration, writing more data than
+the storage space available on the backing file system will result in write
+errors.
+
+The zoned loop block device driver implements a complete zone transition state
+machine. That is, zones can be empty, implicitly opened, explicitly opened,
+closed or full. The current implementation does not support any limits on the
+maximum number of open and active zones.
+
+No user tools are necessary to create and delete zloop devices.
+
+2) Creating a Zoned Device
+--------------------------
+
+Once the zloop module is loaded (or if zloop is compiled in the kernel), the
+character device file /dev/zloop-control can be used to add a zloop device.
+This is done by writing an "add" command directly to the /dev/zloop-control
+device::
+
+	$ modprobe zloop
+        $ ls -l /dev/zloop*
+        crw-------. 1 root root 10, 123 Jan  6 19:18 /dev/zloop-control
+
+        $ mkdir -p <base directory/<device ID>
+        $ echo "add [options]" > /dev/zloop-control
+
+The options available for the add command can be listed by reading the
+/dev/zloop-control device::
+
+	$ cat /dev/zloop-control
+        add id=%d,capacity_mb=%u,zone_size_mb=%u,zone_capacity_mb=%u,conv_zones=%u,base_dir=%s,nr_queues=%u,queue_depth=%u,buffered_io
+        remove id=%d
+
+In more details, the options that can be used with the "add" command are as
+follows.
+
+================   ===========================================================
+id                 Device number (the X in /dev/zloopX).
+                   Default: automatically assigned.
+capacity_mb        Device total capacity in MiB. This is always rounded up to
+                   the nearest higher multiple of the zone size.
+                   Default: 16384 MiB (16 GiB).
+zone_size_mb       Device zone size in MiB. Default: 256 MiB.
+zone_capacity_mb   Device zone capacity (must always be equal to or lower than
+                   the zone size. Default: zone size.
+conv_zones         Total number of conventioanl zones starting from sector 0.
+                   Default: 8.
+base_dir           Path to the base directoy where to create the directory
+                   containing the zone files of the device.
+                   Default=/var/local/zloop.
+                   The device directory containing the zone files is always
+                   named with the device ID. E.g. the default zone file
+                   directory for /dev/zloop0 is /var/local/zloop/0.
+nr_queues          Number of I/O queues of the zoned block device. This value is
+                   always capped by the number of online CPUs
+                   Default: 1
+queue_depth        Maximum I/O queue depth per I/O queue.
+                   Default: 64
+buffered_io        Do buffered IOs instead of direct IOs (default: false)
+================   ===========================================================
+
+3) Deleting a Zoned Device
+--------------------------
+
+Deleting an unused zoned loop block device is done by issuing the "remove"
+command to /dev/zloop-control, specifying the ID of the device to remove::
+
+        $ echo "remove id=X" > /dev/zloop-control
+
+The remove command does not have any option.
+
+A zoned device that was removed can be re-added again without any change to the
+state of the device zones: the device zones are restored to their last state
+before the device was removed. Adding again a zoned device after it was removed
+must always be done using the same configuration as when the device was first
+added. If a zone configuration change is detected, an error will be returned and
+the zoned device will not be created.
+
+To fully delete a zoned device, after executing the remove operation, the device
+base directory containing the backing files of the device zones must be deleted.
+
+4) Example
+----------
+
+The following sequence of commands creates a 2GB zoned device with zones of 64
+MB and a zone capacity of 63 MB::
+
+        $ modprobe zloop
+        $ mkdir -p /var/local/zloop/0
+        $ echo "add capacity_mb=2048,zone_size_mb=64,zone_capacity=63MB" > /dev/zloop-control
+
+For the device created (/dev/zloop0), the zone backing files are all created
+under the default base directory (/var/local/zloop)::
+
+        $ ls -l /var/local/zloop/0
+        total 0
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000000
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000001
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000002
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000003
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000004
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000005
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000006
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000007
+        -rw-------. 1 root root        0 Jan  6 22:23 seq-000008
+        -rw-------. 1 root root        0 Jan  6 22:23 seq-000009
+        ...
+
+The zoned device created (/dev/zloop0) can then be used normally::
+
+        $ lsblk -z
+        NAME   ZONED        ZONE-SZ ZONE-NR ZONE-AMAX ZONE-OMAX ZONE-APP ZONE-WGRAN
+        zloop0 host-managed     64M      32         0         0       1M         4K
+        $ blkzone report /dev/zloop0
+          start: 0x000000000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000020000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000040000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000060000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000080000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x0000a0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x0000c0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x0000e0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000100000, len 0x020000, cap 0x01f800, wptr 0x000000 reset:0 non-seq:0, zcond: 1(em) [type: 2(SEQ_WRITE_REQUIRED)]
+          start: 0x000120000, len 0x020000, cap 0x01f800, wptr 0x000000 reset:0 non-seq:0, zcond: 1(em) [type: 2(SEQ_WRITE_REQUIRED)]
+          ...
+
+Deleting this device is done using the command::
+
+        $ echo "remove id=0" > /dev/zloop-control
+
+The removed device can be re-added again using the same "add" command as when
+the device was first created. To fully delete a zoned device, its backing files
+should also be deleted after executing the remove command::
+
+        $ rm -r /var/local/zloop/0