Merge branch 'for-7.1/block' into for-next

* for-7.1/block:
  MAINTAINERS: update ublk driver maintainer email
  Documentation: ublk: address review comments for SHMEM_ZC docs
  ublk: allow buffer registration before device is started
  ublk: replace xarray with IDA for shmem buffer index allocation
  ublk: simplify PFN range loop in __ublk_ctrl_reg_buf
  ublk: verify all pages in multi-page bvec fall within registered range
  ublk: widen ublk_shmem_buf_reg.len to __u64 for 4GB buffer support

Author: axboe

Documentation/block/ublk.rst

@@ -492,8 +492,8 @@ The ``UBLK_F_SHMEM_ZC`` feature provides an alternative zero-copy path
 that works by sharing physical memory pages between the client application
 and the ublk server. Unlike the io_uring fixed buffer approach above,
 shared memory zero copy does not require io_uring buffer registration
-per I/O — instead, it relies on the kernel matching page frame numbers
-(PFNs) at I/O time. This allows the ublk server to access the shared
+per I/O — instead, it relies on the kernel matching physical pages
+at I/O time. This allows the ublk server to access the shared
 buffer directly, which is unlikely for the io_uring fixed buffer
 approach.
 
@@ -507,8 +507,7 @@ tells the server where the data already lives.
 
 ``UBLK_F_SHMEM_ZC`` can be thought of as a supplement for optimized client
 applications — when the client is willing to allocate I/O buffers from
-shared memory, the entire data path becomes zero-copy without any per-I/O
-overhead.
+shared memory, the entire data path becomes zero-copy.
 
 Use Cases
 ~~~~~~~~~
@@ -584,6 +583,9 @@ Limitations
   the page cache, which allocates its own pages. These kernel-allocated
   pages will never match the registered shared buffer. Only ``O_DIRECT``
   puts the client's buffer pages directly into the block I/O.
+- **Contiguous data only**: each I/O request's data must be contiguous
+  within a single registered buffer. Scatter/gather I/O that spans
+  multiple non-adjacent registered buffers cannot use the zero-copy path.
 
 Control Commands
 ~~~~~~~~~~~~~~~~

MAINTAINERS

@@ -27013,7 +27013,7 @@ F:	Documentation/filesystems/ubifs.rst
 F:	fs/ubifs/
 
 UBLK USERSPACE BLOCK DRIVER
-M:	Ming Lei <ming.lei@redhat.com>
+M:	Ming Lei <tom.leiming@gmail.com>
 L:	linux-block@vger.kernel.org
 S:	Maintained
 F:	Documentation/block/ublk.rst