<feed xmlns='http://www.w3.org/2005/Atom'>
<title>BMC/Intel-BMC/linux.git/include/linux/fs.h, branch dev-5.14-intel</title>
<subtitle>Intel OpenBMC Linux kernel source tree (mirror)</subtitle>
<id>https://git.radix-linux.su/BMC/Intel-BMC/linux.git/atom?h=dev-5.14-intel</id>
<link rel='self' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/atom?h=dev-5.14-intel'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/'/>
<updated>2021-07-05T20:42:16+00:00</updated>
<entry>
<title>Merge tag 'char-misc-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc</title>
<updated>2021-07-05T20:42:16+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-07-05T20:42:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=eed0218e8cae9fcd186c30e9fcf5fe46a87e056e'/>
<id>urn:sha1:eed0218e8cae9fcd186c30e9fcf5fe46a87e056e</id>
<content type='text'>
Pull char / misc driver updates from Greg KH:
 "Here is the big set of char / misc and other driver subsystem updates
  for 5.14-rc1. Included in here are:

   - habanalabs driver updates

   - fsl-mc driver updates

   - comedi driver updates

   - fpga driver updates

   - extcon driver updates

   - interconnect driver updates

   - mei driver updates

   - nvmem driver updates

   - phy driver updates

   - pnp driver updates

   - soundwire driver updates

   - lots of other tiny driver updates for char and misc drivers

  This is looking more and more like the "various driver subsystems
  mushed together" tree...

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'char-misc-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (292 commits)
  mcb: Use DEFINE_RES_MEM() helper macro and fix the end address
  PNP: moved EXPORT_SYMBOL so that it immediately followed its function/variable
  bus: mhi: pci-generic: Add missing 'pci_disable_pcie_error_reporting()' calls
  bus: mhi: Wait for M2 state during system resume
  bus: mhi: core: Fix power down latency
  intel_th: Wait until port is in reset before programming it
  intel_th: msu: Make contiguous buffers uncached
  intel_th: Remove an unused exit point from intel_th_remove()
  stm class: Spelling fix
  nitro_enclaves: Set Bus Master for the NE PCI device
  misc: ibmasm: Modify matricies to matrices
  misc: vmw_vmci: return the correct errno code
  siox: Simplify error handling via dev_err_probe()
  fpga: machxo2-spi: Address warning about unused variable
  lkdtm/heap: Add init_on_alloc tests
  selftests/lkdtm: Enable various testable CONFIGs
  lkdtm: Add CONFIG hints in errors where possible
  lkdtm: Enable DOUBLE_FAULT on all architectures
  lkdtm/heap: Add vmalloc linear overflow test
  lkdtm/bugs: XFAIL UNALIGNED_LOAD_STORE_WRITE
  ...
</content>
</entry>
<entry>
<title>Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs</title>
<updated>2021-07-03T18:41:14+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-07-03T18:41:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=58ec9059b396a570b208239b4edc45eeb68b14c4'/>
<id>urn:sha1:58ec9059b396a570b208239b4edc45eeb68b14c4</id>
<content type='text'>
Pull vfs name lookup updates from Al Viro:
 "Small namei.c patch series, mostly to simplify the rules for nameidata
  state. It's actually from the previous cycle - but I didn't post it
  for review in time...

  Changes visible outside of fs/namei.c: file_open_root() calling
  conventions change, some freed bits in LOOKUP_... space"

* 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  namei: make sure nd-&gt;depth is always valid
  teach set_nameidata() to handle setting the root as well
  take LOOKUP_{ROOT,ROOT_GRABBED,JUMPED} out of LOOKUP_... space
  switch file_open_root() to struct path
</content>
</entry>
<entry>
<title>Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4</title>
<updated>2021-07-01T02:37:39+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-07-01T02:37:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=a6ecc2a491e378e00e65e59a006d4005e1c2f4af'/>
<id>urn:sha1:a6ecc2a491e378e00e65e59a006d4005e1c2f4af</id>
<content type='text'>
Pull ext4 updates from Ted Ts'o:
 "In addition to bug fixes and cleanups, there are two new features for
  ext4 in 5.14:

   - Allow applications to poll on changes to
     /sys/fs/ext4/*/errors_count

   - Add the ioctl EXT4_IOC_CHECKPOINT which allows the journal to be
     checkpointed, truncated and discarded or zero'ed"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (32 commits)
  jbd2: export jbd2_journal_[un]register_shrinker()
  ext4: notify sysfs on errors_count value change
  fs: remove bdev_try_to_free_page callback
  ext4: remove bdev_try_to_free_page() callback
  jbd2: simplify journal_clean_one_cp_list()
  jbd2,ext4: add a shrinker to release checkpointed buffers
  jbd2: remove redundant buffer io error checks
  jbd2: don't abort the journal when freeing buffers
  jbd2: ensure abort the journal if detect IO error when writing original buffer back
  jbd2: remove the out label in __jbd2_journal_remove_checkpoint()
  ext4: no need to verify new add extent block
  jbd2: clean up misleading comments for jbd2_fc_release_bufs
  ext4: add check to prevent attempting to resize an fs with sparse_super2
  ext4: consolidate checks for resize of bigalloc into ext4_resize_begin
  ext4: remove duplicate definition of ext4_xattr_ibody_inline_set()
  ext4: fsmap: fix the block/inode bitmap comment
  ext4: fix comment for s_hash_unsigned
  ext4: use local variable ei instead of EXT4_I() macro
  ext4: fix avefreec in find_group_orlov
  ext4: correct the cache_nr in tracepoint ext4_es_shrink_exit
  ...
</content>
</entry>
<entry>
<title>fs: remove noop_set_page_dirty()</title>
<updated>2021-06-29T17:53:48+00:00</updated>
<author>
<name>Matthew Wilcox (Oracle)</name>
<email>willy@infradead.org</email>
</author>
<published>2021-06-29T02:36:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=b82a96c9253333a8834b2df5f262a39cccf4f6c7'/>
<id>urn:sha1:b82a96c9253333a8834b2df5f262a39cccf4f6c7</id>
<content type='text'>
Use __set_page_dirty_no_writeback() instead.  This will set the dirty bit
on the page, which will be used to avoid calling set_page_dirty() in the
future.  It will have no effect on actually writing the page back, as the
pages are not on any LRU lists.

[akpm@linux-foundation.org: export __set_page_dirty_no_writeback() to modules]

Link: https://lkml.kernel.org/r/20210615162342.1669332-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>fs: move ramfs_aops to libfs</title>
<updated>2021-06-29T17:53:48+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2021-06-29T02:36:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=c1e3dbe9818e3caa4e467255a348df56912ca549'/>
<id>urn:sha1:c1e3dbe9818e3caa4e467255a348df56912ca549</id>
<content type='text'>
Move the ramfs aops to libfs and reuse them for kernfs and configfs.
Thosw two did not wire up -&gt;set_page_dirty before and now get
__set_page_dirty_no_writeback, which is the right one for no-writeback
address_space usage.

Drop the now unused exports of the libfs helpers only used for ramfs-style
pagecache usage.

Link: https://lkml.kernel.org/r/20210614061512.3966143-3-hch@lst.de
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>fs: remove bdev_try_to_free_page callback</title>
<updated>2021-06-24T14:55:42+00:00</updated>
<author>
<name>Zhang Yi</name>
<email>yi.zhang@huawei.com</email>
</author>
<published>2021-06-10T11:24:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=acc6100d3ffa24bdd2add8ea85fb66811bcce5d4'/>
<id>urn:sha1:acc6100d3ffa24bdd2add8ea85fb66811bcce5d4</id>
<content type='text'>
After remove the unique user of sop-&gt;bdev_try_to_free_page() callback,
we could remove the callback and the corresponding blkdev_releasepage()
at all.

Signed-off-by: Zhang Yi &lt;yi.zhang@huawei.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Link: https://lore.kernel.org/r/20210610112440.3438139-9-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
</content>
</entry>
<entry>
<title>remove the raw driver</title>
<updated>2021-06-04T13:35:03+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2021-05-31T07:25:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=603e4922f1c81fc2ed3a87b4f91a8d3aafc7e093'/>
<id>urn:sha1:603e4922f1c81fc2ed3a87b4f91a8d3aafc7e093</id>
<content type='text'>
The raw driver used to provide direct unbuffered access to block devices
before O_DIRECT was invented.  It has been obsolete for more than a
decade.

Acked-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Acked-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Link: https://lore.kernel.org/lkml/Pine.LNX.4.64.0703180754060.6605@CPE00045a9c397f-CM001225dbafb6/
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20210531072526.97052-1-hch@lst.de
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>drivers/char: remove /dev/kmem for good</title>
<updated>2021-05-07T07:26:34+00:00</updated>
<author>
<name>David Hildenbrand</name>
<email>david@redhat.com</email>
</author>
<published>2021-05-07T01:05:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=bbcd53c960713507ae764bf81970651b5577b95a'/>
<id>urn:sha1:bbcd53c960713507ae764bf81970651b5577b95a</id>
<content type='text'>
Patch series "drivers/char: remove /dev/kmem for good".

Exploring /dev/kmem and /dev/mem in the context of memory hot(un)plug and
memory ballooning, I started questioning the existence of /dev/kmem.

Comparing it with the /proc/kcore implementation, it does not seem to be
able to deal with things like

a) Pages unmapped from the direct mapping (e.g., to be used by secretmem)
  -&gt; kern_addr_valid(). virt_addr_valid() is not sufficient.

b) Special cases like gart aperture memory that is not to be touched
  -&gt; mem_pfn_is_ram()

Unless I am missing something, it's at least broken in some cases and might
fault/crash the machine.

Looks like its existence has been questioned before in 2005 and 2010 [1],
after ~11 additional years, it might make sense to revive the discussion.

CONFIG_DEVKMEM is only enabled in a single defconfig (on purpose or by
mistake?).  All distributions disable it: in Ubuntu it has been disabled
for more than 10 years, in Debian since 2.6.31, in Fedora at least
starting with FC3, in RHEL starting with RHEL4, in SUSE starting from
15sp2, and OpenSUSE has it disabled as well.

1) /dev/kmem was popular for rootkits [2] before it got disabled
   basically everywhere. Ubuntu documents [3] "There is no modern user of
   /dev/kmem any more beyond attackers using it to load kernel rootkits.".
   RHEL documents in a BZ [5] "it served no practical purpose other than to
   serve as a potential security problem or to enable binary module drivers
   to access structures/functions they shouldn't be touching"

2) /proc/kcore is a decent interface to have a controlled way to read
   kernel memory for debugging puposes. (will need some extensions to
   deal with memory offlining/unplug, memory ballooning, and poisoned
   pages, though)

3) It might be useful for corner case debugging [1]. KDB/KGDB might be a
   better fit, especially, to write random memory; harder to shoot
   yourself into the foot.

4) "Kernel Memory Editor" [4] hasn't seen any updates since 2000 and seems
   to be incompatible with 64bit [1]. For educational purposes,
   /proc/kcore might be used to monitor value updates -- or older
   kernels can be used.

5) It's broken on arm64, and therefore, completely disabled there.

Looks like it's essentially unused and has been replaced by better
suited interfaces for individual tasks (/proc/kcore, KDB/KGDB). Let's
just remove it.

[1] https://lwn.net/Articles/147901/
[2] https://www.linuxjournal.com/article/10505
[3] https://wiki.ubuntu.com/Security/Features#A.2Fdev.2Fkmem_disabled
[4] https://sourceforge.net/projects/kme/
[5] https://bugzilla.redhat.com/show_bug.cgi?id=154796

Link: https://lkml.kernel.org/r/20210324102351.6932-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210324102351.6932-2-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Acked-by: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: "Alexander A. Klimov" &lt;grandmaster@al2klimov.de&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Alexandre Belloni &lt;alexandre.belloni@bootlin.com&gt;
Cc: Andrew Lunn &lt;andrew@lunn.ch&gt;
Cc: Andrey Zhizhikin &lt;andrey.zhizhikin@leica-geosystems.com&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Brian Cain &lt;bcain@codeaurora.org&gt;
Cc: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Cc: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: Corentin Labbe &lt;clabbe@baylibre.com&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Gerald Schaefer &lt;gerald.schaefer@linux.ibm.com&gt;
Cc: Greentime Hu &lt;green.hu@gmail.com&gt;
Cc: Gregory Clement &lt;gregory.clement@bootlin.com&gt;
Cc: Heiko Carstens &lt;hca@linux.ibm.com&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Hillf Danton &lt;hdanton@sina.com&gt;
Cc: huang ying &lt;huang.ying.caritas@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: "James E.J. Bottomley" &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: James Troup &lt;james.troup@canonical.com&gt;
Cc: Jiaxun Yang &lt;jiaxun.yang@flygoat.com&gt;
Cc: Jonas Bonn &lt;jonas@southpole.se&gt;
Cc: Jonathan Corbet &lt;corbet@lwn.net&gt;
Cc: Kairui Song &lt;kasong@redhat.com&gt;
Cc: Krzysztof Kozlowski &lt;krzk@kernel.org&gt;
Cc: Kuninori Morimoto &lt;kuninori.morimoto.gx@renesas.com&gt;
Cc: Liviu Dudau &lt;liviu.dudau@arm.com&gt;
Cc: Lorenzo Pieralisi &lt;lorenzo.pieralisi@arm.com&gt;
Cc: Luc Van Oostenryck &lt;luc.vanoostenryck@gmail.com&gt;
Cc: Luis Chamberlain &lt;mcgrof@kernel.org&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Mikulas Patocka &lt;mpatocka@redhat.com&gt;
Cc: Minchan Kim &lt;minchan@kernel.org&gt;
Cc: Niklas Schnelle &lt;schnelle@linux.ibm.com&gt;
Cc: Oleksiy Avramchenko &lt;oleksiy.avramchenko@sonymobile.com&gt;
Cc: openrisc@lists.librecores.org
Cc: Palmer Dabbelt &lt;palmerdabbelt@google.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: "Pavel Machek (CIP)" &lt;pavel@denx.de&gt;
Cc: Pavel Machek &lt;pavel@ucw.cz&gt;
Cc: "Peter Zijlstra (Intel)" &lt;peterz@infradead.org&gt;
Cc: Pierre Morel &lt;pmorel@linux.ibm.com&gt;
Cc: Randy Dunlap &lt;rdunlap@infradead.org&gt;
Cc: Richard Henderson &lt;rth@twiddle.net&gt;
Cc: Rich Felker &lt;dalias@libc.org&gt;
Cc: Robert Richter &lt;rric@kernel.org&gt;
Cc: Rob Herring &lt;robh@kernel.org&gt;
Cc: Russell King &lt;linux@armlinux.org.uk&gt;
Cc: Sam Ravnborg &lt;sam@ravnborg.org&gt;
Cc: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Cc: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Cc: sparclinux@vger.kernel.org
Cc: Stafford Horne &lt;shorne@gmail.com&gt;
Cc: Stefan Kristiansson &lt;stefan.kristiansson@saunalahti.fi&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Cc: Theodore Dubois &lt;tblodt@icloud.com&gt;
Cc: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vasily Gorbik &lt;gor@linux.ibm.com&gt;
Cc: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Cc: William Cohen &lt;wcohen@redhat.com&gt;
Cc: Xiaoming Ni &lt;nixiaoming@huawei.com&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm: remove nrexceptional from inode</title>
<updated>2021-05-05T18:27:20+00:00</updated>
<author>
<name>Matthew Wilcox (Oracle)</name>
<email>willy@infradead.org</email>
</author>
<published>2021-05-05T01:32:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=8bc3c481b3d0dcef2cf8e1b7c6b780af6725f7e3'/>
<id>urn:sha1:8bc3c481b3d0dcef2cf8e1b7c6b780af6725f7e3</id>
<content type='text'>
We no longer track anything in nrexceptional, so remove it, saving 8 bytes
per inode.

Link: https://lkml.kernel.org/r/20201026151849.24232-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Tested-by: Vishal Verma &lt;vishal.l.verma@intel.com&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm: provide filemap_range_needs_writeback() helper</title>
<updated>2021-04-30T18:20:36+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2021-04-30T05:55:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/BMC/Intel-BMC/linux.git/commit/?id=63135aa3866db99fd923b716c5ff2e468879624a'/>
<id>urn:sha1:63135aa3866db99fd923b716c5ff2e468879624a</id>
<content type='text'>
Patch series "Improve IOCB_NOWAIT O_DIRECT reads", v3.

An internal workload complained because it was using too much CPU, and
when I took a look, we had a lot of io_uring workers going to town.

For an async buffered read like workload, I am normally expecting _zero_
offloads to a worker thread, but this one had tons of them.  I'd drop
caches and things would look good again, but then a minute later we'd
regress back to using workers.  Turns out that every minute something
was reading parts of the device, which would add page cache for that
inode.  I put patches like these in for our kernel, and the problem was
solved.

Don't -EAGAIN IOCB_NOWAIT dio reads just because we have page cache
entries for the given range.  This causes unnecessary work from the
callers side, when the IO could have been issued totally fine without
blocking on writeback when there is none.

This patch (of 3):

For O_DIRECT reads/writes, we check if we need to issue a call to
filemap_write_and_wait_range() to issue and/or wait for writeback for any
page in the given range.  The existing mechanism just checks for a page in
the range, which is suboptimal for IOCB_NOWAIT as we'll fallback to the
slow path (and needing retry) if there's just a clean page cache page in
the range.

Provide filemap_range_needs_writeback() which tries a little harder to
check if we actually need to issue and/or wait for writeback in the range.

Link: https://lkml.kernel.org/r/20210224164455.1096727-1-axboe@kernel.dk
Link: https://lkml.kernel.org/r/20210224164455.1096727-2-axboe@kernel.dk
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Reviewed-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
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