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Eric Farman 2a07bb64d8 s390/dasd: Remove DMA alignment 
This reverts commit bc792884b7 ("s390/dasd: Establish DMA alignment").

Quoting the original commit:
    linux-next commit bf8d08532b ("iomap: add support for dma aligned
    direct-io") changes the alignment requirement to come from the block
    device rather than the block size, and the default alignment
    requirement is 512-byte boundaries. Since DASD I/O has page
    alignments for IDAW/TIDAW requests, let's override this value to
    restore the expected behavior.

I mentioned TIDAW, but that was wrong. TIDAWs have no distinct alignment
requirement (per p. 15-70 of POPS SA22-7832-13):

   Unless otherwise specified, TIDAWs may designate
   a block of main storage on any boundary and length
   up to 4K bytes, provided the specified block does not
   cross a 4 K-byte boundary.

IDAWs do, but the original commit neglected that while ECKD DASD are
typically formatted in 4096-byte blocks, they don't HAVE to be. Formatting
an ECKD volume with smaller blocks is permitted (dasdfmt -b xxx), and the
problematic commit enforces alignment properties to such a device that
will result in errors, such as:

   [test@host ~]# lsdasd -l a367 | grep blksz
     blksz:				512
   [test@host ~]# mkfs.xfs -f /dev/disk/by-path/ccw-0.0.a367-part1
   meta-data=/dev/dasdc1            isize=512    agcount=4, agsize=230075 blks
            =                       sectsz=512   attr=2, projid32bit=1
            =                       crc=1        finobt=1, sparse=1, rmapbt=1
            =                       reflink=1    bigtime=1 inobtcount=1 nrext64=1
   data     =                       bsize=4096   blocks=920299, imaxpct=25
            =                       sunit=0      swidth=0 blks
   naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
   log      =internal log           bsize=4096   blocks=16384, version=2
            =                       sectsz=512   sunit=0 blks, lazy-count=1
   realtime =none                   extsz=4096   blocks=0, rtextents=0
   error reading existing superblock: Invalid argument
   mkfs.xfs: pwrite failed: Invalid argument
   libxfs_bwrite: write failed on (unknown) bno 0x70565c/0x100, err=22
   mkfs.xfs: Releasing dirty buffer to free list!
   found dirty buffer (bulk) on free list!
   mkfs.xfs: pwrite failed: Invalid argument
   ...snipped...

The original commit omitted the FBA discipline for just this reason,
but the formatted block size of the other disciplines was overlooked.
The solution to all of this is to revert to the original behavior,
such that the block size can be respected. There were two commits [1]
that moved this code in the interim, so a straight git-revert is not
possible, but the change is straightforward.

But what of the original problem? That was manifested with a direct-io
QEMU guest, where QEMU itself was changed a month or two later with
commit 25474d90aa ("block: use the request length for iov alignment")
such that the blamed kernel commit is unnecessary.

[1] commit 0127a47f58 ("dasd: move queue setup to common code")
    commit fde07a4d74 ("dasd: use the atomic queue limits API")

Fixes: bc792884b7 ("s390/dasd: Establish DMA alignment")
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://lore.kernel.org/r/20240812125733.126431-2-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-08-12 10:31:08 -06:00
arch Updates for the interrupt subsystem: 2024-07-22 13:52:05 -07:00
block blk-throttle: remove more latency dead-code 2024-07-27 10:33:25 -06:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto crypto: testmgr - generate power-of-2 lengths more often 2024-07-13 11:50:28 +12:00
Documentation Updates for the interrupt subsystem: 2024-07-22 13:52:05 -07:00
drivers s390/dasd: Remove DMA alignment 2024-08-12 10:31:08 -06:00
fs bcachefs fixes for 6.11-rc1 2024-07-22 10:59:08 -07:00
include nvme fixes for Linux 6.11 2024-07-26 08:06:15 -06:00
init - 875fa64577da ("mm/hugetlb_vmemmap: fix race with speculative PFN 2024-07-21 17:15:46 -07:00
io_uring io_uring: fix error pbuf checking 2024-07-20 11:04:57 -06:00
ipc slab updates for 6.11 2024-07-18 15:08:12 -07:00
kernel Switch ARM/ARM64 over to the modern per device MSI domains: 2024-07-22 14:02:19 -07:00
lib for-6.11/block-20240722 2024-07-22 11:32:05 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm - 875fa64577da ("mm/hugetlb_vmemmap: fix race with speculative PFN 2024-07-21 17:15:46 -07:00
net - In the series "treewide: Refactor heap related implementation", 2024-07-21 17:56:22 -07:00
rust slab updates for 6.11 2024-07-18 15:08:12 -07:00
samples - In the series "treewide: Refactor heap related implementation", 2024-07-21 17:56:22 -07:00
scripts - In the series "treewide: Refactor heap related implementation", 2024-07-21 17:56:22 -07:00
security Landlock updates for v6.11-rc1 2024-07-20 11:41:52 -07:00
sound Char/Misc and other driver changes for 6.11-rc1 2024-07-19 15:55:08 -07:00
tools - In the series "treewide: Refactor heap related implementation", 2024-07-21 17:56:22 -07:00
usr kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
virt KVM generic changes for 6.11 2024-07-16 09:51:36 -04:00
.clang-format Docs: Move clang-format from process/ to dev-tools/ 2024-06-26 16:36:00 -06:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap soc: dt updates for 6.11 2024-07-16 11:43:51 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS tracing: Update of MAINTAINERS and CREDITS file 2024-07-18 14:08:42 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Updates for the interrupt subsystem: 2024-07-22 13:52:05 -07:00
Makefile asm-generic updates for 6.11 2024-07-16 12:09:03 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.