Merge tag 'for-6.3/block-2023-02-16' of git://git.kernel.dk/linux

Pull block updates from Jens Axboe:

 - NVMe updates via Christoph:
      - Small improvements to the logging functionality (Amit Engel)
      - Authentication cleanups (Hannes Reinecke)
      - Cleanup and optimize the DMA mapping cod in the PCIe driver
        (Keith Busch)
      - Work around the command effects for Format NVM (Keith Busch)
      - Misc cleanups (Keith Busch, Christoph Hellwig)
      - Fix and cleanup freeing single sgl (Keith Busch)

 - MD updates via Song:
      - Fix a rare crash during the takeover process
      - Don't update recovery_cp when curr_resync is ACTIVE
      - Free writes_pending in md_stop
      - Change active_io to percpu

 - Updates to drbd, inching us closer to unifying the out-of-tree driver
   with the in-tree one (Andreas, Christoph, Lars, Robert)

 - BFQ update adding support for multi-actuator drives (Paolo, Federico,
   Davide)

 - Make brd compliant with REQ_NOWAIT (me)

 - Fix for IOPOLL and queue entering, fixing stalled IO waiting on
   timeouts (me)

 - Fix for REQ_NOWAIT with multiple bios (me)

 - Fix memory leak in blktrace cleanup (Greg)

 - Clean up sbitmap and fix a potential hang (Kemeng)

 - Clean up some bits in BFQ, and fix a bug in the request injection
   (Kemeng)

 - Clean up the request allocation and issue code, and fix some bugs
   related to that (Kemeng)

 - ublk updates and fixes:
      - Add support for unprivileged ublk (Ming)
      - Improve device deletion handling (Ming)
      - Misc (Liu, Ziyang)

 - s390 dasd fixes (Alexander, Qiheng)

 - Improve utility of request caching and fixes (Anuj, Xiao)

 - zoned cleanups (Pankaj)

 - More constification for kobjs (Thomas)

 - blk-iocost cleanups (Yu)

 - Remove bio splitting from drivers that don't need it (Christoph)

 - Switch blk-cgroups to use struct gendisk. Some of this is now
   incomplete as select late reverts were done. (Christoph)

 - Add bvec initialization helpers, and convert callers to use that
   rather than open-coding it (Christoph)

 - Misc fixes and cleanups (Jinke, Keith, Arnd, Bart, Li, Martin,
   Matthew, Ulf, Zhong)

* tag 'for-6.3/block-2023-02-16' of git://git.kernel.dk/linux: (169 commits)
  brd: use radix_tree_maybe_preload instead of radix_tree_preload
  block: use proper return value from bio_failfast()
  block: bio-integrity: Copy flags when bio_integrity_payload is cloned
  block: Fix io statistics for cgroup in throttle path
  brd: mark as nowait compatible
  brd: check for REQ_NOWAIT and set correct page allocation mask
  brd: return 0/-error from brd_insert_page()
  block: sync mixed merged request's failfast with 1st bio's
  Revert "blk-cgroup: pin the gendisk in struct blkcg_gq"
  Revert "blk-cgroup: pass a gendisk to blkg_lookup"
  Revert "blk-cgroup: delay blk-cgroup initialization until add_disk"
  Revert "blk-cgroup: delay calling blkcg_exit_disk until disk_release"
  Revert "blk-cgroup: move the cgroup information to struct gendisk"
  nvme-pci: remove iod use_sgls
  nvme-pci: fix freeing single sgl
  block: ublk: check IO buffer based on flag need_get_data
  s390/dasd: Fix potential memleak in dasd_eckd_init()
  s390/dasd: sort out physical vs virtual pointers usage
  block: Remove the ALLOC_CACHE_SLACK constant
  block: make kobj_type structures constant
  ...

4 files changed, 48 insertions, 21 deletions

diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block
index cd14ecb3c9a5..ac1e519272aa 100644
--- a/Documentation/ABI/stable/sysfs-block
+++ b/Documentation/ABI/stable/sysfs-block
@@ -432,7 +432,8 @@ Contact:	linux-block@vger.kernel.org
 Description:
 		[RW] This is the maximum number of kilobytes that the block
 		layer will allow for a filesystem request. Must be smaller than
-		or equal to the maximum size allowed by the hardware.
+		or equal to the maximum size allowed by the hardware. Write 0
+		to use default kernel settings.
 
 
 What:		/sys/block/<disk>/queue/max_segment_size
diff --git a/Documentation/block/capability.rst b/Documentation/block/capability.rst
deleted file mode 100644
index 2ae7f064736a..000000000000
--- a/Documentation/block/capability.rst
+++ /dev/null
@@ -1,10 +0,0 @@
-===============================
-Generic Block Device Capability
-===============================
-
-This file documents the sysfs file ``block/<disk>/capability``.
-
-``capability`` is a bitfield, printed in hexadecimal, indicating which
-capabilities a specific block device supports:
-
-.. kernel-doc:: include/linux/blkdev.h
diff --git a/Documentation/block/index.rst b/Documentation/block/index.rst
index c4c73db748a8..102953166429 100644
--- a/Documentation/block/index.rst
+++ b/Documentation/block/index.rst
@@ -10,7 +10,6 @@ Block
    bfq-iosched
    biovecs
    blk-mq
-   capability
    cmdline-partition
    data-integrity
    deadline-iosched
diff --git a/Documentation/block/ublk.rst b/Documentation/block/ublk.rst
index ba45c46cc0da..1713b2890abb 100644
--- a/Documentation/block/ublk.rst
+++ b/Documentation/block/ublk.rst
@@ -144,6 +144,43 @@ managing and controlling ublk devices with help of several control commands:
   For retrieving device info via ``ublksrv_ctrl_dev_info``. It is the server's
   responsibility to save IO target specific info in userspace.
 
+- ``UBLK_CMD_GET_DEV_INFO2``
+  Same purpose with ``UBLK_CMD_GET_DEV_INFO``, but ublk server has to
+  provide path of the char device of ``/dev/ublkc*`` for kernel to run
+  permission check, and this command is added for supporting unprivileged
+  ublk device, and introduced with ``UBLK_F_UNPRIVILEGED_DEV`` together.
+  Only the user owning the requested device can retrieve the device info.
+
+  How to deal with userspace/kernel compatibility:
+
+  1) if kernel is capable of handling ``UBLK_F_UNPRIVILEGED_DEV``
+
+    If ublk server supports ``UBLK_F_UNPRIVILEGED_DEV``:
+
+    ublk server should send ``UBLK_CMD_GET_DEV_INFO2``, given anytime
+    unprivileged application needs to query devices the current user owns,
+    when the application has no idea if ``UBLK_F_UNPRIVILEGED_DEV`` is set
+    given the capability info is stateless, and application should always
+    retrieve it via ``UBLK_CMD_GET_DEV_INFO2``
+
+    If ublk server doesn't support ``UBLK_F_UNPRIVILEGED_DEV``:
+
+    ``UBLK_CMD_GET_DEV_INFO`` is always sent to kernel, and the feature of
+    UBLK_F_UNPRIVILEGED_DEV isn't available for user
+
+  2) if kernel isn't capable of handling ``UBLK_F_UNPRIVILEGED_DEV``
+
+    If ublk server supports ``UBLK_F_UNPRIVILEGED_DEV``:
+
+    ``UBLK_CMD_GET_DEV_INFO2`` is tried first, and will be failed, then
+    ``UBLK_CMD_GET_DEV_INFO`` needs to be retried given
+    ``UBLK_F_UNPRIVILEGED_DEV`` can't be set
+
+    If ublk server doesn't support ``UBLK_F_UNPRIVILEGED_DEV``:
+
+    ``UBLK_CMD_GET_DEV_INFO`` is always sent to kernel, and the feature of
+    ``UBLK_F_UNPRIVILEGED_DEV`` isn't available for user
+
 - ``UBLK_CMD_START_USER_RECOVERY``
 
   This command is valid if ``UBLK_F_USER_RECOVERY`` feature is enabled. This
@@ -180,6 +217,15 @@ managing and controlling ublk devices with help of several control commands:
   double-write since the driver may issue the same I/O request twice. It
   might be useful to a read-only FS or a VM backend.
 
+Unprivileged ublk device is supported by passing ``UBLK_F_UNPRIVILEGED_DEV``.
+Once the flag is set, all control commands can be sent by unprivileged
+user. Except for command of ``UBLK_CMD_ADD_DEV``, permission check on
+the specified char device(``/dev/ublkc*``) is done for all other control
+commands by ublk driver, for doing that, path of the char device has to
+be provided in these commands' payload from ublk server. With this way,
+ublk device becomes container-ware, and device created in one container
+can be controlled/accessed just inside this container.
+
 Data plane
 ----------
 
@@ -254,15 +300,6 @@ with specified IO tag in the command data:
 Future development
 ==================
 
-Container-aware ublk deivice
-----------------------------
-
-ublk driver doesn't handle any IO logic. Its function is well defined
-for now and very limited userspace interfaces are needed, which is also
-well defined too. It is possible to make ublk devices container-aware block
-devices in future as Stefan Hajnoczi suggested [#stefan]_, by removing
-ADMIN privilege.
-
 Zero copy
 ---------