linux.git/fs/f2fs, branch v4.14 Linux kernel source tree License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02T10:10:55+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2017-11-01T14:07:57+00:00 b24413180f5600bcb3bb70fbed5cf186b60864bd Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
f2fs: fix potential panic during fstrim 2017-10-03T15:06:05+00:00 Chao Yu yuchao0@huawei.com 2017-10-01T18:50:16+00:00 638164a2718f337ea224b747cf5977ef143166a4 As Ju Hyung Park reported: "When 'fstrim' is called for manual trim, a BUG() can be triggered randomly with this patch. I'm seeing this issue on both x86 Desktop and arm64 Android phone. On x86 Desktop, this was caused during Ubuntu boot-up. I have a cronjob installed which calls 'fstrim -v /' during boot. On arm64 Android, this was caused during GC looping with 1ms gc_min_sleep_time & gc_max_sleep_time." Root cause of this issue is that f2fs_wait_discard_bios can only be used by f2fs_put_super, because during put_super there must be no other referrers, so it can ignore discard entry's reference count when removing the entry, otherwise in other caller we will hit bug_on in __remove_discard_cmd as there may be other issuer added reference count in discard entry. Thread A Thread B - issue_discard_thread - f2fs_ioc_fitrim - f2fs_trim_fs - f2fs_wait_discard_bios - __issue_discard_cmd - __submit_discard_cmd - __wait_discard_cmd - dc->ref++ - __wait_one_discard_bio - __wait_discard_cmd - __remove_discard_cmd - f2fs_bug_on(sbi, dc->ref) Fixes: 969d1b180d987c2be02de890d0fff0f66a0e80de Reported-by: Ju Hyung Park <qkrwngud825@gmail.com> Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
As Ju Hyung Park reported:

"When 'fstrim' is called for manual trim, a BUG() can be triggered
randomly with this patch.

I'm seeing this issue on both x86 Desktop and arm64 Android phone.

On x86 Desktop, this was caused during Ubuntu boot-up. I have a
cronjob installed which calls 'fstrim -v /' during boot. On arm64
Android, this was caused during GC looping with 1ms gc_min_sleep_time
& gc_max_sleep_time."

Root cause of this issue is that f2fs_wait_discard_bios can only be
used by f2fs_put_super, because during put_super there must be no
other referrers, so it can ignore discard entry's reference count
when removing the entry, otherwise in other caller we will hit bug_on
in __remove_discard_cmd as there may be other issuer added reference
count in discard entry.

Thread A				Thread B
					- issue_discard_thread
- f2fs_ioc_fitrim
 - f2fs_trim_fs
  - f2fs_wait_discard_bios
   - __issue_discard_cmd
    - __submit_discard_cmd
					 - __wait_discard_cmd
					  - dc->ref++
					  - __wait_one_discard_bio
   - __wait_discard_cmd
    - __remove_discard_cmd
     - f2fs_bug_on(sbi, dc->ref)

Fixes: 969d1b180d987c2be02de890d0fff0f66a0e80de
Reported-by: Ju Hyung Park <qkrwngud825@gmail.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Merge tag 'f2fs-for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs 2017-09-13T03:05:58+00:00 Linus Torvalds torvalds@linux-foundation.org 2017-09-13T03:05:58+00:00 6d8ef53e8b2fed8b0f91df0c6da7cc92747d934a Pull f2fs updates from Jaegeuk Kim: "In this round, we've mostly tuned f2fs to provide better user experience for Android. Especially, we've worked on atomic write feature again with SQLite community in order to support it officially. And we added or modified several facilities to analyze and enhance IO behaviors. Major changes include: - add app/fs io stat - add inode checksum feature - support project/journalled quota - enhance atomic write with new ioctl() which exposes feature set - enhance background gc/discard/fstrim flows with new gc_urgent mode - add F2FS_IOC_FS{GET,SET}XATTR - fix some quota flows" * tag 'f2fs-for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (63 commits) f2fs: hurry up to issue discard after io interruption f2fs: fix to show correct discard_granularity in sysfs f2fs: detect dirty inode in evict_inode f2fs: clear radix tree dirty tag of pages whose dirty flag is cleared f2fs: speed up gc_urgent mode with SSR f2fs: better to wait for fstrim completion f2fs: avoid race in between read xattr & write xattr f2fs: make get_lock_data_page to handle encrypted inode f2fs: use generic terms used for encrypted block management f2fs: introduce f2fs_encrypted_file for clean-up Revert "f2fs: add a new function get_ssr_cost" f2fs: constify super_operations f2fs: fix to wake up all sleeping flusher f2fs: avoid race in between atomic_read & atomic_inc f2fs: remove unneeded parameter of change_curseg f2fs: update i_flags correctly f2fs: don't check inode's checksum if it was dirtied or writebacked f2fs: don't need to update inode checksum for recovery f2fs: trigger fdatasync for non-atomic_write file f2fs: fix to avoid race in between aio and gc ... 
Pull f2fs updates from Jaegeuk Kim:
 "In this round, we've mostly tuned f2fs to provide better user
  experience for Android. Especially, we've worked on atomic write
  feature again with SQLite community in order to support it officially.
  And we added or modified several facilities to analyze and enhance IO
  behaviors.

  Major changes include:
   - add app/fs io stat
   - add inode checksum feature
   - support project/journalled quota
   - enhance atomic write with new ioctl() which exposes feature set
   - enhance background gc/discard/fstrim flows with new gc_urgent mode
   - add F2FS_IOC_FS{GET,SET}XATTR
   - fix some quota flows"

* tag 'f2fs-for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (63 commits)
  f2fs: hurry up to issue discard after io interruption
  f2fs: fix to show correct discard_granularity in sysfs
  f2fs: detect dirty inode in evict_inode
  f2fs: clear radix tree dirty tag of pages whose dirty flag is cleared
  f2fs: speed up gc_urgent mode with SSR
  f2fs: better to wait for fstrim completion
  f2fs: avoid race in between read xattr & write xattr
  f2fs: make get_lock_data_page to handle encrypted inode
  f2fs: use generic terms used for encrypted block management
  f2fs: introduce f2fs_encrypted_file for clean-up
  Revert "f2fs: add a new function get_ssr_cost"
  f2fs: constify super_operations
  f2fs: fix to wake up all sleeping flusher
  f2fs: avoid race in between atomic_read & atomic_inc
  f2fs: remove unneeded parameter of change_curseg
  f2fs: update i_flags correctly
  f2fs: don't check inode's checksum if it was dirtied or writebacked
  f2fs: don't need to update inode checksum for recovery
  f2fs: trigger fdatasync for non-atomic_write file
  f2fs: fix to avoid race in between aio and gc
  ...
f2fs: hurry up to issue discard after io interruption 2017-09-12T17:02:55+00:00 Chao Yu yuchao0@huawei.com 2017-09-12T13:35:12+00:00 e6c6de18f010d9a7d592f4044d2c30213cb3a7bc Once we encounter I/O interruption during issuing discards, we will delay long time before next round, but if system status is I/O idle during the time, it may loses opportunity to issue discards. So this patch changes to hurry up to issue discard after io interruption. Besides, this patch also fixes to issue discards accurately with assigned rate. Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
Once we encounter I/O interruption during issuing discards, we will delay
long time before next round, but if system status is I/O idle during the
time, it may loses opportunity to issue discards. So this patch changes
to hurry up to issue discard after io interruption.

Besides, this patch also fixes to issue discards accurately with assigned
rate.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: fix to show correct discard_granularity in sysfs 2017-09-12T17:02:47+00:00 Chao Yu yuchao0@huawei.com 2017-09-12T06:25:35+00:00 80647e5f4c728ecea7d9190c6e7163755ff6835c Fix below incorrect display when reading discard_granularity sysfs node. $ cat /sys/fs/f2fs/<device>/discard_granularity $ 16 $ echo 32 > /sys/fs/f2fs/<device>/discard_granularity $ cat /sys/fs/f2fs/<device>/discard_granularity $ 16 Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
Fix below incorrect display when reading discard_granularity sysfs node.

$ cat /sys/fs/f2fs/<device>/discard_granularity
$ 16
$ echo 32 > /sys/fs/f2fs/<device>/discard_granularity
$ cat /sys/fs/f2fs/<device>/discard_granularity
$ 16

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: detect dirty inode in evict_inode 2017-09-12T17:02:39+00:00 Chao Yu yuchao0@huawei.com 2017-09-12T06:04:05+00:00 ca7d802a7d8ee4c47dce9be86ef4b27e587086bb Add a bugon in f2fs_evict_inode to detect inconsistent status between inode cache and related node page cache. Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
Add a bugon in f2fs_evict_inode to detect inconsistent status between
inode cache and related node page cache.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: clear radix tree dirty tag of pages whose dirty flag is cleared 2017-09-12T04:32:38+00:00 Daeho Jeong daeho.jeong@samsung.com 2017-09-11T07:30:28+00:00 0abd8e70d24b665dd00972d4a259e05528cbf4c6 On a senario like writing out the first dirty page of the inode as the inline data, we only cleared dirty flags of the pages, but didn't clear the dirty tags of those pages in the radix tree. If we don't clear the dirty tags of the pages in the radix tree, the inodes which contain the pages will be marked with I_DIRTY_PAGES again and again, and writepages() for the inodes will be invoked in every writeback period. As a result, nothing will be done in every writepages() for the inodes and it will just consume CPU time meaninglessly. Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
On a senario like writing out the first dirty page of the inode
as the inline data, we only cleared dirty flags of the pages, but
didn't clear the dirty tags of those pages in the radix tree.

If we don't clear the dirty tags of the pages in the radix tree, the
inodes which contain the pages will be marked with I_DIRTY_PAGES again
and again, and writepages() for the inodes will be invoked in every
writeback period. As a result, nothing will be done in every
writepages() for the inodes and it will just consume CPU time
meaninglessly.

Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: speed up gc_urgent mode with SSR 2017-09-12T00:22:18+00:00 Jaegeuk Kim jaegeuk@kernel.org 2017-09-09T18:11:04+00:00 b3a97a2a9a7b2d50bcf13d32857cd6f5695c6b65 This patch activates SSR in gc_urgent mode. Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
This patch activates SSR in gc_urgent mode.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: better to wait for fstrim completion 2017-09-12T00:22:12+00:00 Jaegeuk Kim jaegeuk@kernel.org 2017-09-09T19:03:23+00:00 1eb1ef4a8e9f6a4d9c2c7a645aba21d2f8719728 In android, we'd better wait for fstrim completion instead of issuing the discard commands asynchronous. Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
In android, we'd better wait for fstrim completion instead of issuing the
discard commands asynchronous.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY 2017-09-09T01:26:46+00:00 Jérôme Glisse jglisse@redhat.com 2017-09-08T23:12:06+00:00 2916ecc0f9d435d849c98f4da50e453124c87531 Introduce a new migration mode that allow to offload the copy to a device DMA engine. This changes the workflow of migration and not all address_space migratepage callback can support this. This is intended to be use by migrate_vma() which itself is use for thing like HMM (see include/linux/hmm.h). No additional per-filesystem migratepage testing is needed. I disables MIGRATE_SYNC_NO_COPY in all problematic migratepage() callback and i added comment in those to explain why (part of this patch). The commit message is unclear it should say that any callback that wish to support this new mode need to be aware of the difference in the migration flow from other mode. Some of these callbacks do extra locking while copying (aio, zsmalloc, balloon, ...) and for DMA to be effective you want to copy multiple pages in one DMA operations. But in the problematic case you can not easily hold the extra lock accross multiple call to this callback. Usual flow is: For each page { 1 - lock page 2 - call migratepage() callback 3 - (extra locking in some migratepage() callback) 4 - migrate page state (freeze refcount, update page cache, buffer head, ...) 5 - copy page 6 - (unlock any extra lock of migratepage() callback) 7 - return from migratepage() callback 8 - unlock page } The new mode MIGRATE_SYNC_NO_COPY: 1 - lock multiple pages For each page { 2 - call migratepage() callback 3 - abort in all problematic migratepage() callback 4 - migrate page state (freeze refcount, update page cache, buffer head, ...) } // finished all calls to migratepage() callback 5 - DMA copy multiple pages 6 - unlock all the pages To support MIGRATE_SYNC_NO_COPY in the problematic case we would need a new callback migratepages() (for instance) that deals with multiple pages in one transaction. Because the problematic cases are not important for current usage I did not wanted to complexify this patchset even more for no good reason. Link: http://lkml.kernel.org/r/20170817000548.32038-14-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Nellans <dnellans@nvidia.com> Cc: Evgeny Baskakov <ebaskakov@nvidia.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mark Hairgrove <mhairgrove@nvidia.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Sherry Cheung <SCheung@nvidia.com> Cc: Subhash Gutti <sgutti@nvidia.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Bob Liu <liubo95@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Introduce a new migration mode that allow to offload the copy to a device
DMA engine.  This changes the workflow of migration and not all
address_space migratepage callback can support this.

This is intended to be use by migrate_vma() which itself is use for thing
like HMM (see include/linux/hmm.h).

No additional per-filesystem migratepage testing is needed.  I disables
MIGRATE_SYNC_NO_COPY in all problematic migratepage() callback and i
added comment in those to explain why (part of this patch).  The commit
message is unclear it should say that any callback that wish to support
this new mode need to be aware of the difference in the migration flow
from other mode.

Some of these callbacks do extra locking while copying (aio, zsmalloc,
balloon, ...) and for DMA to be effective you want to copy multiple
pages in one DMA operations.  But in the problematic case you can not
easily hold the extra lock accross multiple call to this callback.

Usual flow is:

For each page {
 1 - lock page
 2 - call migratepage() callback
 3 - (extra locking in some migratepage() callback)
 4 - migrate page state (freeze refcount, update page cache, buffer
     head, ...)
 5 - copy page
 6 - (unlock any extra lock of migratepage() callback)
 7 - return from migratepage() callback
 8 - unlock page
}

The new mode MIGRATE_SYNC_NO_COPY:
 1 - lock multiple pages
For each page {
 2 - call migratepage() callback
 3 - abort in all problematic migratepage() callback
 4 - migrate page state (freeze refcount, update page cache, buffer
     head, ...)
} // finished all calls to migratepage() callback
 5 - DMA copy multiple pages
 6 - unlock all the pages

To support MIGRATE_SYNC_NO_COPY in the problematic case we would need a
new callback migratepages() (for instance) that deals with multiple
pages in one transaction.

Because the problematic cases are not important for current usage I did
not wanted to complexify this patchset even more for no good reason.

Link: http://lkml.kernel.org/r/20170817000548.32038-14-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>