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Adrian Huang c2affe920b dax: do not print error message for non-persistent memory block device
Commit 231609785c ("dax: print error message by pr_info()
in __generic_fsdax_supported()") happens to print the following
error message during booting when the non-persistent memory block
devices are configured by device mapper. Those error messages are
caused by the variable 'dax_dev' is NULL. Users might be confused
with those error messages since they do not use the persistent
memory device. Moreover, users might scare about "what's wrong
with my disks" because they see the 'error' and 'failed' keywords.

  # dmesg | grep fail
  sdk3: error: dax access failed (-95)
  sdk3: error: dax access failed (-95)
  sdk3: error: dax access failed (-95)
  sdk3: error: dax access failed (-95)
  sdk3: error: dax access failed (-95)
  sdk3: error: dax access failed (-95)
  sdk3: error: dax access failed (-95)
  sdk3: error: dax access failed (-95)
  sdk3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)
  sdb3: error: dax access failed (-95)

  # lsblk
  NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
  sda               8:0    0   1.1T  0 disk
  ├─sda1            8:1    0   156M  0 part
  ├─sda2            8:2    0    40G  0 part
  └─sda3            8:3    0   1.1T  0 part
  sdb               8:16   0   1.1T  0 disk
  ├─sdb1            8:17   0   600M  0 part
  ├─sdb2            8:18   0     1G  0 part
  └─sdb3            8:19   0   1.1T  0 part
    ├─rhel00-swap 254:3    0     4G  0 lvm
    ├─rhel00-home 254:4    0     1T  0 lvm
    └─rhel00-root 254:5    0    50G  0 lvm
  sdc               8:32   0   1.1T  0 disk
  sdd               8:48   0   1.1T  0 disk
  sde               8:64   0   1.1T  0 disk
  sdf               8:80   0   1.1T  0 disk
  sdg               8:96   0   1.1T  0 disk
  sdh               8:112  0   3.3T  0 disk
  ├─sdh1            8:113  0   500M  0 part /boot/efi
  ├─sdh2            8:114  0    40G  0 part /
  ├─sdh3            8:115  0   2.9T  0 part /home
  └─sdh4            8:116  0 314.6G  0 part [SWAP]
  sdi               8:128  0   1.1T  0 disk
  sdj               8:144  0   3.3T  0 disk
  ├─sdj1            8:145  0   512M  0 part
  └─sdj2            8:146  0   3.3T  0 part
  sdk               8:160  0 119.2G  0 disk
  ├─sdk1            8:161  0   200M  0 part
  ├─sdk2            8:162  0     1G  0 part
  └─sdk3            8:163  0   118G  0 part
    ├─rhel-swap   254:0    0     4G  0 lvm
    ├─rhel-home   254:1    0    64G  0 lvm
    └─rhel-root   254:2    0    50G  0 lvm
  sdl               8:176  0 119.2G  0 disk

The call path is shown as follows:
  dm_table_determine_type
    dm_table_supports_dax
     device_supports_dax
       generic_fsdax_supported
        __generic_fsdax_supported

With the disk configuration listing from the command 'lsblk',
the member 'dev->dax_dev' of the block devices 'sdb3' and 'sdk3'
(configured by device mapper) is NULL in function
generic_fsdax_supported() because the member is configured in
function open_table_device().

To prevent the confusing error messages in this scenario (this is
normal behavior), just print those error messages by pr_debug()
by checking if dax_dev is NULL and the block device does not support
DAX.

Link: https://lore.kernel.org/r/20200819154236.24191-1-adrianhuang0701@gmail.com
Fixes: 231609785c ("dax: print error message by pr_info() in __generic_fsdax_supported()")
Cc: Coly Li <colyli@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
2020-08-20 11:43:18 -06:00
Documentation Misc fixes and small updates all around the place: 2020-08-15 10:38:03 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch parisc: fix PMD pages allocation by restoring pmd_alloc_one() 2020-08-16 10:53:13 -07:00
block block-5.9-2020-08-14 2020-08-15 20:36:42 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-08-14 13:09:15 -07:00
drivers dax: do not print error message for non-persistent memory block device 2020-08-20 11:43:18 -06:00
fs io_uring-5.9-2020-08-15 2020-08-16 10:55:12 -07:00
include io_uring-5.9-2020-08-15 2020-08-16 10:55:12 -07:00
init OpenRISC updates for 5.9 2020-08-14 14:04:53 -07:00
ipc ipc/shm.c: remove the superfluous break 2020-08-12 10:58:02 -07:00
kernel io_uring-5.9-2020-08-15 2020-08-16 10:55:12 -07:00
lib iomap: constify ioreadX() iomem argument (as in generic implementation) 2020-08-14 19:56:57 -07:00
mm Merge branch 'akpm' (patches from Andrew) 2020-08-15 08:02:03 -07:00
net 9p pull request for inclusion in 5.9 2020-08-15 08:34:36 -07:00
samples Kbuild updates for v5.9 2020-08-09 14:10:26 -07:00
scripts Kconfig updates for v5.9 2020-08-14 11:04:45 -07:00
security Merge branch 'akpm' (patches from Andrew) 2020-08-12 11:24:12 -07:00
sound sound fixes for 5.9-rc1 2020-08-14 15:58:57 -07:00
tools Cleanup, SECCOMP_FILTER support, message printing fixes, and other 2020-08-15 18:50:32 -07:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt Merge branch 'akpm' (patches from Andrew) 2020-08-12 11:24:12 -07:00
.clang-format block: add bio_for_each_bvec_all() 2020-05-25 11:25:24 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: Add ZSTD-compressed files 2020-07-31 11:50:49 +02:00
.mailmap mailmap: add entry for Greg Kurz 2020-08-14 19:56:56 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: Replace HTTP links with HTTPS ones 2020-07-23 14:53:58 -06:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS perf tools changes for v5.9: 2nd batch 2020-08-15 11:17:15 -07:00
Makefile Linux 5.9-rc1 2020-08-16 13:04:57 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 Restructured Text 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.