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Bart Van Assche 8fe8ffb12c scsi: Suppress a kernel warning in case the prep function returns BLKPREP_DEFER
The legacy block layer handles requests as follows:
- If the prep function returns BLKPREP_OK, let blk_peek_request()
  return the pointer to that request.
- If the prep function returns BLKPREP_DEFER, keep the RQF_STARTED
  flag and retry calling the prep function later.
- If the prep function returns BLKPREP_KILL or BLKPREP_INVALID, end
  the request.

In none of these cases it is correct to clear the SCMD_INITIALIZED
flag from inside scsi_prep_fn(). Since scsi_prep_fn() already
guarantees that scsi_init_command() will be called once even if
scsi_prep_fn() is called multiple times, remove the code that clears
SCMD_INITIALIZED from scsi_prep_fn().

The scsi-mq code handles requests as follows:
- If scsi_mq_prep_fn() returns BLKPREP_OK, set the RQF_DONTPREP flag
  and submit the request to the SCSI LLD.
- If scsi_mq_prep_fn() returns BLKPREP_DEFER, call
  blk_mq_delay_run_hw_queue() and return BLK_STS_RESOURCE.
- If the prep function returns BLKPREP_KILL or BLKPREP_INVALID, call
  scsi_mq_uninit_cmd() and let the blk-mq core end the request.

In none of these cases scsi_mq_prep_fn() should clear the
SCMD_INITIALIZED flag. Hence remove the code from scsi_mq_prep_fn()
function that clears that flag.

This patch avoids that the following warning is triggered when using
the legacy block layer:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 4198 at drivers/scsi/scsi_lib.c:654 scsi_end_request+0x1de/0x220
CPU: 1 PID: 4198 Comm: mkfs.f2fs Not tainted 4.14.0-rc5+ #1
task: ffff91c147a4b800 task.stack: ffffb282c37b8000
RIP: 0010:scsi_end_request+0x1de/0x220
Call Trace:
<IRQ>
scsi_io_completion+0x204/0x5e0
scsi_finish_command+0xce/0xe0
scsi_softirq_done+0x126/0x130
blk_done_softirq+0x6e/0x80
__do_softirq+0xcf/0x2a8
irq_exit+0xab/0xb0
do_IRQ+0x7b/0xc0
common_interrupt+0x90/0x90
</IRQ>
RIP: 0010:_raw_spin_unlock_irqrestore+0x9/0x10
__test_set_page_writeback+0xc7/0x2c0
__block_write_full_page+0x158/0x3b0
block_write_full_page+0xc4/0xd0
blkdev_writepage+0x13/0x20
__writepage+0x12/0x40
write_cache_pages+0x204/0x500
generic_writepages+0x48/0x70
blkdev_writepages+0x9/0x10
do_writepages+0x34/0xc0
__filemap_fdatawrite_range+0x6c/0x90
file_write_and_wait_range+0x31/0x90
blkdev_fsync+0x16/0x40
vfs_fsync_range+0x44/0xa0
do_fsync+0x38/0x60
SyS_fsync+0xb/0x10
entry_SYSCALL_64_fastpath+0x13/0x94
---[ end trace 86e8ef85a4a6c1d1 ]---

Fixes: commit 64104f7032 ("scsi: Call scsi_initialize_rq() for filesystem requests")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2017-10-23 04:19:45 -04:00
arch The diff is dominated by the Allwinner A10/A20 SoCs getting converted to 2017-09-13 11:04:14 -07:00
block block: directly insert blk-mq request from blk_insert_cloned_request() 2017-09-11 16:43:57 -06:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto crypto: af_alg - get_page upon reassignment to TX SGL 2017-08-22 15:03:27 +08:00
Documentation The diff is dominated by the Allwinner A10/A20 SoCs getting converted to 2017-09-13 11:04:14 -07:00
drivers scsi: Suppress a kernel warning in case the prep function returns BLKPREP_DEFER 2017-10-23 04:19:45 -04:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse 2017-09-13 10:10:19 -07:00
include scsi: libiscsi: Remove iscsi_destroy_session 2017-10-02 22:23:21 -04:00
init init/main.c: extract early boot entropy from the passed cmdline 2017-09-08 18:26:50 -07:00
ipc ipc: optimize semget/shmget/msgget for lots of keys 2017-09-08 18:26:51 -07:00
kernel selinux/stable-4.14 PR 20170831 2017-09-12 13:21:00 -07:00
lib libnvdimm for 4.14 2017-09-11 13:10:57 -07:00
mm mm/backing-dev.c: fix an error handling path in 'cgwb_create()' 2017-09-11 14:16:44 -06:00
net The highlights include: 2017-09-12 20:03:53 -07:00
samples media updates for v4.14-rc1 2017-09-07 12:53:14 -07:00
scripts A cleanup from Mauro that needed to wait for the media pull, plus a handful 2017-09-13 10:18:34 -07:00
security selinux/stable-4.14 PR 20170831 2017-09-12 13:21:00 -07:00
sound The diff is dominated by the Allwinner A10/A20 SoCs getting converted to 2017-09-13 11:04:14 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-12 11:28:13 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt First batch of KVM changes for 4.14 2017-09-08 15:18:36 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS selinux/stable-4.14 PR 20170831 2017-09-12 13:21:00 -07:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS Fix up MAINTAINERS file sorting 2017-09-13 11:18:19 -07:00
Makefile Merge branch 'docs-next' of git://git.lwn.net/linux 2017-09-03 21:07:29 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.