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https://android.googlesource.com/kernel/common into lineage-18.1-caf-msm8998
This brings LA.UM.9.2.r1-02500-SDMxx0.0 up to date with
https://android.googlesource.com/kernel/common/ android-4.4-p at commit:
4fd124d1546d8 Merge 4.4.258 into android-4.4-p
Change-Id: Idbae7489bc1d831a378dd60993f46139e5e28c4c
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[ Upstream commit 68f23b89067fdf187763e75a56087550624fdbee ]
Without memcg, there is a one-to-one mapping between the bdi and
bdi_writeback structures. In this world, things are fairly
straightforward; the first thing bdi_unregister() does is to shutdown
the bdi_writeback structure (or wb), and part of that writeback ensures
that no other work queued against the wb, and that the wb is fully
drained.
With memcg, however, there is a one-to-many relationship between the bdi
and bdi_writeback structures; that is, there are multiple wb objects
which can all point to a single bdi. There is a refcount which prevents
the bdi object from being released (and hence, unregistered). So in
theory, the bdi_unregister() *should* only get called once its refcount
goes to zero (bdi_put will drop the refcount, and when it is zero,
release_bdi gets called, which calls bdi_unregister).
Unfortunately, del_gendisk() in block/gen_hd.c never got the memo about
the Brave New memcg World, and calls bdi_unregister directly. It does
this without informing the file system, or the memcg code, or anything
else. This causes the root wb associated with the bdi to be
unregistered, but none of the memcg-specific wb's are shutdown. So when
one of these wb's are woken up to do delayed work, they try to
dereference their wb->bdi->dev to fetch the device name, but
unfortunately bdi->dev is now NULL, thanks to the bdi_unregister()
called by del_gendisk(). As a result, *boom*.
Fortunately, it looks like the rest of the writeback path is perfectly
happy with bdi->dev and bdi->owner being NULL, so the simplest fix is to
create a bdi_dev_name() function which can handle bdi->dev being NULL.
This also allows us to bulletproof the writeback tracepoints to prevent
them from dereferencing a NULL pointer and crashing the kernel if one is
tracing with memcg's enabled, and an iSCSI device dies or a USB storage
stick is pulled.
The most common way of triggering this will be hotremoval of a device
while writeback with memcg enabled is going on. It was triggering
several times a day in a heavily loaded production environment.
Google Bug Id: 145475544
Link: https://lore.kernel.org/r/20191227194829.150110-1-tytso@mit.edu
Link: http://lkml.kernel.org/r/20191228005211.163952-1-tytso@mit.edu
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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* refs/heads/tmp-b1c4836
Linux 4.4.129
writeback: safer lock nesting
fanotify: fix logic of events on child
ext4: bugfix for mmaped pages in mpage_release_unused_pages()
mm/filemap.c: fix NULL pointer in page_cache_tree_insert()
mm: allow GFP_{FS,IO} for page_cache_read page cache allocation
autofs: mount point create should honour passed in mode
Don't leak MNT_INTERNAL away from internal mounts
rpc_pipefs: fix double-dput()
hypfs_kill_super(): deal with failed allocations
jffs2_kill_sb(): deal with failed allocations
powerpc/lib: Fix off-by-one in alternate feature patching
powerpc/eeh: Fix enabling bridge MMIO windows
MIPS: memset.S: Fix clobber of v1 in last_fixup
MIPS: memset.S: Fix return of __clear_user from Lpartial_fixup
MIPS: memset.S: EVA & fault support for small_memset
MIPS: uaccess: Add micromips clobbers to bzero invocation
HID: hidraw: Fix crash on HIDIOCGFEATURE with a destroyed device
ALSA: hda - New VIA controller suppor no-snoop path
ALSA: rawmidi: Fix missing input substream checks in compat ioctls
ALSA: line6: Use correct endpoint type for midi output
ext4: fix deadlock between inline_data and ext4_expand_extra_isize_ea()
ext4: fix crashes in dioread_nolock mode
drm/radeon: Fix PCIe lane width calculation
ext4: don't allow r/w mounts if metadata blocks overlap the superblock
vfio/pci: Virtualize Maximum Read Request Size
vfio/pci: Virtualize Maximum Payload Size
vfio-pci: Virtualize PCIe & AF FLR
ALSA: pcm: Fix endless loop for XRUN recovery in OSS emulation
ALSA: pcm: Fix mutex unbalance in OSS emulation ioctls
ALSA: pcm: Return -EBUSY for OSS ioctls changing busy streams
ALSA: pcm: Avoid potential races between OSS ioctls and read/write
ALSA: pcm: Use ERESTARTSYS instead of EINTR in OSS emulation
ALSA: oss: consolidate kmalloc/memset 0 call to kzalloc
watchdog: f71808e_wdt: Fix WD_EN register read
thermal: imx: Fix race condition in imx_thermal_probe()
clk: bcm2835: De-assert/assert PLL reset signal when appropriate
clk: mvebu: armada-38x: add support for missing clocks
clk: mvebu: armada-38x: add support for 1866MHz variants
mmc: jz4740: Fix race condition in IRQ mask update
iommu/vt-d: Fix a potential memory leak
um: Use POSIX ucontext_t instead of struct ucontext
dmaengine: at_xdmac: fix rare residue corruption
IB/srp: Fix completion vector assignment algorithm
IB/srp: Fix srp_abort()
ALSA: pcm: Fix UAF at PCM release via PCM timer access
RDMA/ucma: Don't allow setting RDMA_OPTION_IB_PATH without an RDMA device
ext4: fail ext4_iget for root directory if unallocated
ext4: don't update checksum of new initialized bitmaps
jbd2: if the journal is aborted then don't allow update of the log tail
random: use a tighter cap in credit_entropy_bits_safe()
thunderbolt: Resume control channel after hibernation image is created
ASoC: ssm2602: Replace reg_default_raw with reg_default
HID: core: Fix size as type u32
HID: Fix hid_report_len usage
powerpc/powernv: Fix OPAL NVRAM driver OPAL_BUSY loops
powerpc/powernv: define a standard delay for OPAL_BUSY type retry loops
powerpc/64: Fix smp_wmb barrier definition use use lwsync consistently
powerpc/powernv: Handle unknown OPAL errors in opal_nvram_write()
HID: i2c-hid: fix size check and type usage
usb: dwc3: pci: Properly cleanup resource
USB:fix USB3 devices behind USB3 hubs not resuming at hibernate thaw
ACPI / hotplug / PCI: Check presence of slot itself in get_slot_status()
ACPI / video: Add quirk to force acpi-video backlight on Samsung 670Z5E
regmap: Fix reversed bounds check in regmap_raw_write()
xen-netfront: Fix hang on device removal
ARM: dts: at91: sama5d4: fix pinctrl compatible string
ARM: dts: at91: at91sam9g25: fix mux-mask pinctrl property
usb: musb: gadget: misplaced out of bounds check
mm, slab: reschedule cache_reap() on the same CPU
ipc/shm: fix use-after-free of shm file via remap_file_pages()
resource: fix integer overflow at reallocation
fs/reiserfs/journal.c: add missing resierfs_warning() arg
ubi: Reject MLC NAND
ubi: Fix error for write access
ubi: fastmap: Don't flush fastmap work on detach
ubifs: Check ubifs_wbuf_sync() return code
tty: make n_tty_read() always abort if hangup is in progress
x86/hweight: Don't clobber %rdi
x86/hweight: Get rid of the special calling convention
lan78xx: Correctly indicate invalid OTP
slip: Check if rstate is initialized before uncompressing
cdc_ether: flag the Cinterion AHS8 modem by gemalto as WWAN
hwmon: (ina2xx) Fix access to uninitialized mutex
rtl8187: Fix NULL pointer dereference in priv->conf_mutex
getname_kernel() needs to make sure that ->name != ->iname in long case
s390/ipl: ensure loadparm valid flag is set
s390/qdio: don't merge ERROR output buffers
s390/qdio: don't retry EQBS after CCQ 96
block/loop: fix deadlock after loop_set_status
Revert "perf tests: Decompress kernel module before objdump"
radeon: hide pointless #warning when compile testing
perf intel-pt: Fix timestamp following overflow
perf intel-pt: Fix error recovery from missing TIP packet
perf intel-pt: Fix sync_switch
perf intel-pt: Fix overlap detection to identify consecutive buffers correctly
parisc: Fix out of array access in match_pci_device()
media: v4l2-compat-ioctl32: don't oops on overlay
f2fs: check cap_resource only for data blocks
Revert "f2fs: introduce f2fs_set_page_dirty_nobuffer"
f2fs: clear PageError on writepage
UPSTREAM: timer: Export destroy_hrtimer_on_stack()
BACKPORT: dm verity: add 'check_at_most_once' option to only validate hashes once
f2fs: call unlock_new_inode() before d_instantiate()
f2fs: refactor read path to allow multiple postprocessing steps
fscrypt: allow synchronous bio decryption
Change-Id: I45f4ac10734d92023b53118d83dcd6c83974a283
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>
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commit 2e898e4c0a3897ccd434adac5abb8330194f527b upstream.
lock_page_memcg()/unlock_page_memcg() use spin_lock_irqsave/restore() if
the page's memcg is undergoing move accounting, which occurs when a
process leaves its memcg for a new one that has
memory.move_charge_at_immigrate set.
unlocked_inode_to_wb_begin,end() use spin_lock_irq/spin_unlock_irq() if
the given inode is switching writeback domains. Switches occur when
enough writes are issued from a new domain.
This existing pattern is thus suspicious:
lock_page_memcg(page);
unlocked_inode_to_wb_begin(inode, &locked);
...
unlocked_inode_to_wb_end(inode, locked);
unlock_page_memcg(page);
If both inode switch and process memcg migration are both in-flight then
unlocked_inode_to_wb_end() will unconditionally enable interrupts while
still holding the lock_page_memcg() irq spinlock. This suggests the
possibility of deadlock if an interrupt occurs before unlock_page_memcg().
truncate
__cancel_dirty_page
lock_page_memcg
unlocked_inode_to_wb_begin
unlocked_inode_to_wb_end
<interrupts mistakenly enabled>
<interrupt>
end_page_writeback
test_clear_page_writeback
lock_page_memcg
<deadlock>
unlock_page_memcg
Due to configuration limitations this deadlock is not currently possible
because we don't mix cgroup writeback (a cgroupv2 feature) and
memory.move_charge_at_immigrate (a cgroupv1 feature).
If the kernel is hacked to always claim inode switching and memcg
moving_account, then this script triggers lockup in less than a minute:
cd /mnt/cgroup/memory
mkdir a b
echo 1 > a/memory.move_charge_at_immigrate
echo 1 > b/memory.move_charge_at_immigrate
(
echo $BASHPID > a/cgroup.procs
while true; do
dd if=/dev/zero of=/mnt/big bs=1M count=256
done
) &
while true; do
sync
done &
sleep 1h &
SLEEP=$!
while true; do
echo $SLEEP > a/cgroup.procs
echo $SLEEP > b/cgroup.procs
done
The deadlock does not seem possible, so it's debatable if there's any
reason to modify the kernel. I suggest we should to prevent future
surprises. And Wang Long said "this deadlock occurs three times in our
environment", so there's more reason to apply this, even to stable.
Stable 4.4 has minor conflicts applying this patch. For a clean 4.4 patch
see "[PATCH for-4.4] writeback: safer lock nesting"
https://lkml.org/lkml/2018/4/11/146
Wang Long said "this deadlock occurs three times in our environment"
[gthelen@google.com: v4]
Link: http://lkml.kernel.org/r/20180411084653.254724-1-gthelen@google.com
[akpm@linux-foundation.org: comment tweaks, struct initialization simplification]
Change-Id: Ibb773e8045852978f6207074491d262f1b3fb613
Link: http://lkml.kernel.org/r/20180410005908.167976-1-gthelen@google.com
Fixes: 682aa8e1a6a1 ("writeback: implement unlocked_inode_to_wb transaction and use it for stat updates")
Signed-off-by: Greg Thelen <gthelen@google.com>
Reported-by: Wang Long <wanglong19@meituan.com>
Acked-by: Wang Long <wanglong19@meituan.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: <stable@vger.kernel.org> [v4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[natechancellor: Applied to 4.4 based on Greg's backport on lkml.org]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Instead of storing backing_dev_info inside struct request_queue,
allocate it dynamically, reference count it, and free it when the last
reference is dropped. Currently only request_queue holds the reference
but in the following patch we add other users referencing
backing_dev_info.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Change-Id: Ibcee7b4c014018f9243cd3edbfd9c4a8877c3862
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
Git-commit: d03f6cdc1fc422accb734c7c07a661a0018d8631
[riteshh@codeaurora.org: resolved merge conflicts]
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
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commit df08c32ce3be5be138c1dbfcba203314a3a7cd6f upstream.
The name for a bdi of a gendisk is derived from the gendisk's devt.
However, since the gendisk is destroyed before the bdi it leaves a
window where a new gendisk could dynamically reuse the same devt while a
bdi with the same name is still live. Arrange for the bdi to hold a
reference against its "owner" disk device while it is registered.
Otherwise we can hit sysfs duplicate name collisions like the following:
WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80
sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1'
Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015
0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec
ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351
0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8
Call Trace:
[<ffffffff8134caec>] dump_stack+0x63/0x87
[<ffffffff8108c351>] __warn+0xd1/0xf0
[<ffffffff8108c3cf>] warn_slowpath_fmt+0x5f/0x80
[<ffffffff812a0d34>] sysfs_warn_dup+0x64/0x80
[<ffffffff812a0e1e>] sysfs_create_dir_ns+0x7e/0x90
[<ffffffff8134faaa>] kobject_add_internal+0xaa/0x320
[<ffffffff81358d4e>] ? vsnprintf+0x34e/0x4d0
[<ffffffff8134ff55>] kobject_add+0x75/0xd0
[<ffffffff816e66b2>] ? mutex_lock+0x12/0x2f
[<ffffffff8148b0a5>] device_add+0x125/0x610
[<ffffffff8148b788>] device_create_groups_vargs+0xd8/0x100
[<ffffffff8148b7cc>] device_create_vargs+0x1c/0x20
[<ffffffff811b775c>] bdi_register+0x8c/0x180
[<ffffffff811b7877>] bdi_register_dev+0x27/0x30
[<ffffffff813317f5>] add_disk+0x175/0x4a0
Reported-by: Yi Zhang <yizhan@redhat.com>
Tested-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixed up missing 0 return in bdi_register_owner().
Signed-off-by: Jens Axboe <axboe@fb.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
"The cgroup core saw several significant updates this cycle:
- percpu_rwsem for threadgroup locking is reinstated. This was
temporarily dropped due to down_write latency issues. Oleg's
rework of percpu_rwsem which is scheduled to be merged in this
merge window resolves the issue.
- On the v2 hierarchy, when controllers are enabled and disabled, all
operations are atomic and can fail and revert cleanly. This allows
->can_attach() failure which is necessary for cpu RT slices.
- Tasks now stay associated with the original cgroups after exit
until released. This allows tracking resources held by zombies
(e.g. pids) and makes it easy to find out where zombies came from
on the v2 hierarchy. The pids controller was broken before these
changes as zombies escaped the limits; unfortunately, updating this
behavior required too many invasive changes and I don't think it's
a good idea to backport them, so the pids controller on 4.3, the
first version which included the pids controller, will stay broken
at least until I'm sure about the cgroup core changes.
- Optimization of a couple common tests using static_key"
* 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (38 commits)
cgroup: fix race condition around termination check in css_task_iter_next()
blkcg: don't create "io.stat" on the root cgroup
cgroup: drop cgroup__DEVEL__legacy_files_on_dfl
cgroup: replace error handling in cgroup_init() with WARN_ON()s
cgroup: add cgroup_subsys->free() method and use it to fix pids controller
cgroup: keep zombies associated with their original cgroups
cgroup: make css_set_rwsem a spinlock and rename it to css_set_lock
cgroup: don't hold css_set_rwsem across css task iteration
cgroup: reorganize css_task_iter functions
cgroup: factor out css_set_move_task()
cgroup: keep css_set and task lists in chronological order
cgroup: make cgroup_destroy_locked() test cgroup_is_populated()
cgroup: make css_sets pin the associated cgroups
cgroup: relocate cgroup_[try]get/put()
cgroup: move check_for_release() invocation
cgroup: replace cgroup_has_tasks() with cgroup_is_populated()
cgroup: make cgroup->nr_populated count the number of populated css_sets
cgroup: remove an unused parameter from cgroup_task_migrate()
cgroup: fix too early usage of static_branch_disable()
cgroup: make cgroup_update_dfl_csses() migrate all target processes atomically
...
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bdi's are initialized in two steps, bdi_init() and bdi_register(), but
destroyed in a single step by bdi_destroy() which, for a bdi embedded
in a request_queue, is called during blk_cleanup_queue() which makes
the queue invisible and starts the draining of remaining usages.
A request_queue's user can access the congestion state of the embedded
bdi as long as it holds a reference to the queue. As such, it may
access the congested state of a queue which finished
blk_cleanup_queue() but hasn't reached blk_release_queue() yet.
Because the congested state was embedded in backing_dev_info which in
turn is embedded in request_queue, accessing the congested state after
bdi_destroy() was called was fine. The bdi was destroyed but the
memory region for the congested state remained accessible till the
queue got released.
a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in
bdi_writeback") changed the situation. Now, the root congested state
which is expected to be pinned while request_queue remains accessible
is separately reference counted and the base ref is put during
bdi_destroy(). This means that the root congested state may go away
prematurely while the queue is between bdi_dstroy() and
blk_cleanup_queue(), which was detected by Andrey's KASAN tests.
The root cause of this problem is that bdi doesn't distinguish the two
steps of destruction, unregistration and release, and now the root
congested state actually requires a separate release step. To fix the
issue, this patch separates out bdi_unregister() and bdi_exit() from
bdi_destroy(). bdi_unregister() is called from blk_cleanup_queue()
and bdi_exit() from blk_release_queue(). bdi_destroy() is now just a
simple wrapper calling the two steps back-to-back.
While at it, the prototype of bdi_destroy() is moved right below
bdi_setup_and_register() so that the counterpart operations are
located together.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in bdi_writeback")
Cc: stable@vger.kernel.org # v4.2+
Reported-and-tested-by: Andrey Konovalov <andreyknvl@google.com>
Link: http://lkml.kernel.org/g/CAAeHK+zUJ74Zn17=rOyxacHU18SgCfC6bsYW=6kCY5GXJBwGfQ@mail.gmail.com
Reviewed-by: Jan Kara <jack@suse.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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bdi_for_each_wb() is used in several places to wake up or issue
writeback work items to all wb's (bdi_writeback's) on a given bdi.
The iteration is performed by walking bdi->cgwb_tree; however, the
tree only indexes wb's which are currently active.
For example, when a memcg gets associated with a different blkcg, the
old wb is removed from the tree so that the new one can be indexed.
The old wb starts dying from then on but will linger till all its
inodes are drained. As these dying wb's may still host dirty inodes,
writeback operations which affect all wb's must include them.
bdi_for_each_wb() skipping dying wb's led to sync(2) missing and
failing to sync the inodes belonging to those wb's.
This patch adds a RCU protected @bdi->wb_list which lists all wb's
beloinging to that bdi. wb's are added on creation and removed on
release rather than on the start of destruction. bdi_for_each_wb()
usages are replaced with list_for_each[_continue]_rcu() iterations
over @bdi->wb_list and bdi_for_each_wb() and its helpers are removed.
v2: Updated as per Jan. last_wb ref leak in bdi_split_work_to_wbs()
fixed and unnecessary list head severing in cgwb_bdi_destroy()
removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Artem Bityutskiy <dedekind1@gmail.com>
Fixes: ebe41ab0c79d ("writeback: implement bdi_for_each_wb()")
Link: http://lkml.kernel.org/g/1443012552.19983.209.camel@gmail.com
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Pull to receive 9badce000e2c ("cgroup, writeback: don't enable cgroup
writeback on traditional hierarchies"). The commit adds
cgroup_on_dfl() usages in include/linux/backing-dev.h thus causing a
silent conflict with 9e10a130d9b6 ("cgroup: replace cgroup_on_dfl()
tests in controllers with cgroup_subsys_on_dfl()"). The conflict is
fixed during this merge.
Signed-off-by: Tejun Heo <tj@kernel.org>
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inode_cgwb_enabled() gates cgroup writeback support. If it returns
true, each inode is attached to the corresponding memory domain which
gets mapped to io domain. It currently only tests whether the
filesystem and bdi support cgroup writeback; however, cgroup writeback
support doesn't work on traditional hierarchies and thus it should
also test whether memcg and iocg are on the default hierarchy.
This caused traditional hierarchy setups to hit the cgroup writeback
path inadvertently and ended up creating separate writeback domains
for each memcg and mapping them all to the root iocg uncovering a
couple issues in the cgroup writeback path.
cgroup writeback was never meant to be enabled on traditional
hierarchies. Make inode_cgwb_enabled() test whether both memcg and
iocg are on the default hierarchy.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Artem Bityutskiy <dedekind1@gmail.com>
Reported-by: Dexuan Cui <decui@microsoft.com>
Link: http://lkml.kernel.org/g/1443012552.19983.209.camel@gmail.com
Link: http://lkml.kernel.org/g/f30d4a6aa8a546ff88f73021d026a453@SIXPR30MB031.064d.mgd.msft.net
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blkio interface has become messy over time and is currently the
largest. In addition to the inconsistent naming scheme, it has
multiple stat files which report more or less the same thing, a number
of debug stat files which expose internal details which shouldn't have
been part of the public interface in the first place, recursive and
non-recursive stats and leaf and non-leaf knobs.
Both recursive vs. non-recursive and leaf vs. non-leaf distinctions
don't make any sense on the unified hierarchy as only leaf cgroups can
contain processes. cgroups is going through a major interface
revision with the unified hierarchy involving significant fundamental
usage changes and given that a significant portion of the interface
doesn't make sense anymore, it's a good time to reorganize the
interface.
As the first step, this patch renames the external visible subsystem
name from "blkio" to "io". This is more concise, matches the other
two major subsystem names, "cpu" and "memory", and better suited as
blkcg will be involved in anything writeback related too whether an
actual block device is involved or not.
As the subsystem legacy_name is set to "blkio", the only userland
visible change outside the unified hierarchy is that blkcg is reported
as "io" instead of "blkio" in the subsystem initialized message during
boot. On the unified hierarchy, blkcg now appears as "io".
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: cgroups@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
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wb's (bdi_writeback's) are currently keyed by memcg ID; however, in an
earlier implementation, wb's were keyed by blkcg ID.
bdi_for_each_wb() walks bdi->cgwb_tree in the ascending ID order and
allows iterations to start from an arbitrary ID which is used to
interrupt and resume iterations.
Unfortunately, while changing wb to be keyed by memcg ID instead of
blkcg, bdi_for_each_wb() was missed and is still assuming that wb's
are keyed by blkcg ID. This doesn't affect iterations which don't get
interrupted but bdi_split_work_to_wbs() makes use of iteration
resuming on allocation failures and thus may incorrectly skip or
repeat wb's.
Fix it by changing bdi_for_each_wb() to take memcg IDs instead of
blkcg IDs and updating bdi_split_work_to_wbs() accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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52ebea749aae ("writeback: make backing_dev_info host cgroup-specific
bdi_writebacks") made bdi (backing_dev_info) host per-cgroup wb's
(bdi_writeback's). As the congested state needs to be per-wb and
referenced from blkcg side and multiple wbs, the patch made all
non-root cong's (bdi_writeback_congested's) reference counted and
indexed on bdi.
When a bdi is destroyed, cgwb_bdi_destroy() tries to drain all
non-root cong's; however, this can hang indefinitely because wb's can
also be referenced from blkcg_gq's which are destroyed after bdi
destruction is complete.
To fix the bug, bdi destruction will be updated to not wait for cong's
to drain, which naturally means that cong's may outlive the associated
bdi. This is fine for non-root cong's but is problematic for the root
cong's which are embedded in their bdi's as they may end up getting
dereferenced after the containing bdi's are freed.
This patch makes root cong's behave the same as non-root cong's. They
are no longer embedded in their bdi's but allocated separately during
bdi initialization, indexed and reference counted the same way.
* As cong handling is the same for all wb's, wb->congested
initialization is moved into wb_init().
* When !CONFIG_CGROUP_WRITEBACK, there was no indexing or refcnting.
bdi->wb_congested is now a pointer pointing to the root cong
allocated during bdi init and minimal refcnting operations are
implemented.
* The above makes root wb init paths diverge depending on
CONFIG_CGROUP_WRITEBACK. root wb init is moved to cgwb_bdi_init().
This patch in itself shouldn't cause any consequential behavior
differences but prepares for the actual fix.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jon Christopherson <jon@jons.org>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=100681
Tested-by: Jon Christopherson <jon@jons.org>
Added <linux/slab.h> include to backing-dev.h for kfree() definition.
Signed-off-by: Jens Axboe <axboe@fb.com>
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Pull cgroup writeback support from Jens Axboe:
"This is the big pull request for adding cgroup writeback support.
This code has been in development for a long time, and it has been
simmering in for-next for a good chunk of this cycle too. This is one
of those problems that has been talked about for at least half a
decade, finally there's a solution and code to go with it.
Also see last weeks writeup on LWN:
http://lwn.net/Articles/648292/"
* 'for-4.2/writeback' of git://git.kernel.dk/linux-block: (85 commits)
writeback, blkio: add documentation for cgroup writeback support
vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB
writeback: do foreign inode detection iff cgroup writeback is enabled
v9fs: fix error handling in v9fs_session_init()
bdi: fix wrong error return value in cgwb_create()
buffer: remove unusued 'ret' variable
writeback: disassociate inodes from dying bdi_writebacks
writeback: implement foreign cgroup inode bdi_writeback switching
writeback: add lockdep annotation to inode_to_wb()
writeback: use unlocked_inode_to_wb transaction in inode_congested()
writeback: implement unlocked_inode_to_wb transaction and use it for stat updates
writeback: implement [locked_]inode_to_wb_and_lock_list()
writeback: implement foreign cgroup inode detection
writeback: make writeback_control track the inode being written back
writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb()
mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use
writeback: implement memcg writeback domain based throttling
writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes
writeback: implement memcg wb_domain
writeback: update wb_over_bg_thresh() to use wb_domain aware operations
...
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FS_CGROUP_WRITEBACK indicates whether a file_system_type supports
cgroup writeback; however, different super_blocks of the same
file_system_type may or may not support cgroup writeback depending on
filesystem options. This patch replaces FS_CGROUP_WRITEBACK with a
per-super_block flag.
super_block->s_flags carries some internal flags in the high bits but
it's exposd to userland through uapi header and running out of space
anyway. This patch adds a new field super_block->s_iflags to carry
kernel-internal flags. It is currently only used by the new
SB_I_CGROUPWB flag whose concatenated and abbreviated name is for
consistency with other super_block flags.
ext2_fill_super() is updated to set SB_I_CGROUPWB.
v2: Added super_block->s_iflags instead of stealing another high bit
from sb->s_flags as suggested by Christoph and Jan.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: linux-ext4@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
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With the previous three patches, all operations which acquire wb from
inode are either under one of inode->i_lock, mapping->tree_lock or
wb->list_lock or protected by unlocked_inode_to_wb transaction. This
will be depended upon by foreign inode wb switching.
This patch adds lockdep assertion to inode_to_wb() so that usages
outside the above list locks can be caught easily. There are three
exceptions.
* locked_inode_to_wb_and_lock_list() is holding wb->list_lock but the
wb may not be the inode's. Ensuring that is the function's role
after all. Updated to deref inode->i_wb directly.
* inode_wb_stat_unlocked_begin() is usually protected by combination
of !I_WB_SWITCH and rcu_read_lock(). Updated to deref inode->i_wb
directly.
* inode_congested() wants to test whether inode->i_wb is set before
starting the transaction. Added inode_to_wb_is_valid() which tests
inode->i_wb directly.
v5: might_lock() removed. It annotates that the lock is grabbed w/
irq enabled which isn't the case and triggering lockdep warning
spuriously.
v4: might_lock() added to unlocked_inode_to_wb_begin().
v3: inode_congested() conversion added.
v2: locked_inode_to_wb_and_lock_list() was missing in the first
version.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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updates
The mechanism for detecting whether an inode should switch its wb
(bdi_writeback) association is now in place. This patch build the
framework for the actual switching.
This patch adds a new inode flag I_WB_SWITCHING, which has two
functions. First, the easy one, it ensures that there's only one
switching in progress for a give inode. Second, it's used as a
mechanism to synchronize wb stat updates.
The two stats, WB_RECLAIMABLE and WB_WRITEBACK, aren't event counters
but track the current number of dirty pages and pages under writeback
respectively. As such, when an inode is moved from one wb to another,
the inode's portion of those stats have to be transferred together;
unfortunately, this is a bit tricky as those stat updates are percpu
operations which are performed without holding any lock in some
places.
This patch solves the problem in a similar way as memcg. Each such
lockless stat updates are wrapped in transaction surrounded by
unlocked_inode_to_wb_begin/end(). During normal operation, they map
to rcu_read_lock/unlock(); however, if I_WB_SWITCHING is asserted,
mapping->tree_lock is grabbed across the transaction.
In turn, the switching path sets I_WB_SWITCHING and waits for a RCU
grace period to pass before actually starting to switch, which
guarantees that all stat update paths are synchronizing against
mapping->tree_lock.
This patch still doesn't implement the actual switching.
v3: Updated on top of the recent cancel_dirty_page() updates.
unlocked_inode_to_wb_begin() now nests inside
mem_cgroup_begin_page_stat() to match the locking order.
v2: The i_wb access transaction will be used for !stat accesses too.
Function names and comments updated accordingly.
s/inode_wb_stat_unlocked_{begin|end}/unlocked_inode_to_wb_{begin|end}/
s/switch_wb/switch_wbs/
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, for cgroup writeback, the IO submission paths directly
associate the bio's with the blkcg from inode_to_wb_blkcg_css();
however, it'd be necessary to keep more writeback context to implement
foreign inode writeback detection. wbc (writeback_control) is the
natural fit for the extra context - it persists throughout the
writeback of each inode and is passed all the way down to IO
submission paths.
This patch adds wbc_attach_and_unlock_inode(), wbc_detach_inode(), and
wbc_attach_fdatawrite_inode() which are used to associate wbc with the
inode being written back. IO submission paths now use wbc_init_bio()
instead of directly associating bio's with blkcg themselves. This
leaves inode_to_wb_blkcg_css() w/o any user. The function is removed.
wbc currently only tracks the associated wb (bdi_writeback). Future
patches will add more for foreign inode detection. The association is
established under i_lock which will be depended upon when migrating
foreign inodes to other wb's.
As currently, once established, inode to wb association never changes,
going through wbc when initializing bio's doesn't cause any behavior
changes.
v2: submit_blk_blkcg() now checks whether the wbc is associated with a
wb before dereferencing it. This can happen when pageout() is
writing pages directly without going through the usual writeback
path. As pageout() path is single-threaded, we don't want it to
be blocked behind a slow cgroup and ultimately want it to delegate
actual writing to the usual writeback path.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, majority of cgroup writeback support including all the
above functions are implemented in include/linux/backing-dev.h and
mm/backing-dev.c; however, the portion closely related to writeback
logic implemented in include/linux/writeback.h and mm/page-writeback.c
will expand to support foreign writeback detection and correction.
This patch moves wb[_try]_get() and wb_put() to
include/linux/backing-dev-defs.h so that they can be used from
writeback.h and inode_{attach|detach}_wb() to writeback.h and
page-writeback.c.
This is pure reorganization and doesn't introduce any functional
changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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[__]block_write_full_page() is used to implement ->writepage in
various filesystems. All writeback logic is now updated to handle
cgroup writeback and the block cgroup to issue IOs for is encoded in
writeback_control and can be retrieved from the inode; however,
[__]block_write_full_page() currently ignores the blkcg indicated by
inode and issues all bio's without explicit blkcg association.
This patch adds submit_bh_blkcg() which associates the bio with the
specified blkio cgroup before issuing and uses it in
__block_write_full_page() so that the issued bio's are associated with
inode_to_wb_blkcg_css(inode).
v2: Updated for per-inode wb association.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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of backing_dev_info
bdi_start_background_writeback() currently takes @bdi and kicks the
root wb (bdi_writeback). In preparation for cgroup writeback support,
make it take wb instead.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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backing_dev_info
writeback_in_progress() currently takes @bdi and returns whether
writeback is in progress on its root wb (bdi_writeback). In
preparation for cgroup writeback support, make it take wb instead.
While at it, make it an inline function.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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bdi_start_writeback() is a thin wrapper on top of
__wb_start_writeback() which is used only by laptop_mode_timer_fn().
This patches removes bdi_start_writeback(), renames
__wb_start_writeback() to wb_start_writeback() and makes
laptop_mode_timer_fn() use it instead.
This doesn't cause any functional difference and will ease making
laptop_mode_timer_fn() cgroup writeback aware.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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This will be used to implement bdi-wide operations which should be
distributed across all its cgroup bdi_writebacks.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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bdi_has_dirty_io() used to only reflect whether the root wb
(bdi_writeback) has dirty inodes. For cgroup writeback support, it
needs to take all active wb's into account. If any wb on the bdi has
dirty inodes, bdi_has_dirty_io() should return true.
To achieve that, as inode_wb_list_{move|del}_locked() now keep track
of the dirty state transition of each wb, the number of dirty wbs can
be counted in the bdi; however, bdi is already aggregating
wb->avg_write_bandwidth which can easily be guaranteed to be > 0 when
there are any dirty inodes by ensuring wb->avg_write_bandwidth can't
dip below 1. bdi_has_dirty_io() can simply test whether
bdi->tot_write_bandwidth is zero or not.
While this bumps the value of wb->avg_write_bandwidth to one when it
used to be zero, this shouldn't cause any meaningful behavior
difference.
bdi_has_dirty_io() is made an inline function which tests whether
->tot_write_bandwidth is non-zero. Also, WARN_ON_ONCE()'s on its
value are added to inode_wb_list_{move|del}_locked().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, wb_has_dirty_io() determines whether a wb (bdi_writeback)
has any dirty inode by testing all three IO lists on each invocation
without actively keeping track. For cgroup writeback support, a
single bdi will host multiple wb's each of which will host dirty
inodes separately and we'll need to make bdi_has_dirty_io(), which
currently only represents the root wb, aggregate has_dirty_io from all
member wb's, which requires tracking transitions in has_dirty_io state
on each wb.
This patch introduces inode_wb_list_{move|del}_locked() to consolidate
IO list operations leaving queue_io() the only other function which
directly manipulates IO lists (via move_expired_inodes()). All three
functions are updated to call wb_io_lists_[de]populated() which keep
track of whether the wb has dirty inodes or not and record it using
the new WB_has_dirty_io flag. inode_wb_list_moved_locked()'s return
value indicates whether the wb had no dirty inodes before.
mark_inode_dirty() is restructured so that the return value of
inode_wb_list_move_locked() can be used for deciding whether to wake
up the wb.
While at it, change {bdi|wb}_has_dirty_io()'s return values to bool.
These functions were returning 0 and 1 before. Also, add a comment
explaining the synchronization of wb_state flags.
v2: Updated to accommodate b_dirty_time.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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In several places, bdi_congested() and its wrappers are used to
determine whether more IOs should be issued. With cgroup writeback
support, this question can't be answered solely based on the bdi
(backing_dev_info). It's dependent on whether the filesystem and bdi
support cgroup writeback and the blkcg the inode is associated with.
This patch implements inode_congested() and its wrappers which take
@inode and determines the congestion state considering cgroup
writeback. The new functions replace bdi_*congested() calls in places
where the query is about specific inode and task.
There are several filesystem users which also fit this criteria but
they should be updated when each filesystem implements cgroup
writeback support.
v2: Now that a given inode is associated with only one wb, congestion
state can be determined independent from the asking task. Drop
@task. Spotted by Vivek. Also, converted to take @inode instead
of @mapping and renamed to inode_congested().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, all congestion functions take bdi (backing_dev_info) and
always operate on the root wb (bdi->wb) and the congestion state from
the block layer is propagated only for the root blkcg. This patch
introduces {set|clear}_wb_congested() and wb_congested() which take a
bdi_writeback_congested and bdi_writeback respectively. The bdi
counteparts are now wrappers invoking the wb based functions on
@bdi->wb.
While converting clear_bdi_congested() to clear_wb_congested(), the
local variable declaration order between @wqh and @bit is swapped for
cosmetic reason.
This patch just adds the new wb based functions. The following
patches will apply them.
v2: Updated for bdi_writeback_congested.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@fb.com>
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For the planned cgroup writeback support, on each bdi
(backing_dev_info), each memcg will be served by a separate wb
(bdi_writeback). This patch updates bdi so that a bdi can host
multiple wbs (bdi_writebacks).
On the default hierarchy, blkcg implicitly enables memcg. This allows
using memcg's page ownership for attributing writeback IOs, and every
memcg - blkcg combination can be served by its own wb by assigning a
dedicated wb to each memcg. This means that there may be multiple
wb's of a bdi mapped to the same blkcg. As congested state is per
blkcg - bdi combination, those wb's should share the same congested
state. This is achieved by tracking congested state via
bdi_writeback_congested structs which are keyed by blkcg.
bdi->wb remains unchanged and will keep serving the root cgroup.
cgwb's (cgroup wb's) for non-root cgroups are created on-demand or
looked up while dirtying an inode according to the memcg of the page
being dirtied or current task. Each cgwb is indexed on bdi->cgwb_tree
by its memcg id. Once an inode is associated with its wb, it can be
retrieved using inode_to_wb().
Currently, none of the filesystems has FS_CGROUP_WRITEBACK and all
pages will keep being associated with bdi->wb.
v3: inode_attach_wb() in account_page_dirtied() moved inside
mapping_cap_account_dirty() block where it's known to be !NULL.
Also, an unnecessary NULL check before kfree() removed. Both
detected by the kbuild bot.
v2: Updated so that wb association is per inode and wb is per memcg
rather than blkcg.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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cgroup writeback requires support from both bdi and filesystem sides.
Add BDI_CAP_CGROUP_WRITEBACK and FS_CGROUP_WRITEBACK to indicate
support and enable BDI_CAP_CGROUP_WRITEBACK on block based bdi's by
default. Also, define CONFIG_CGROUP_WRITEBACK which is enabled if
both MEMCG and BLK_CGROUP are enabled.
inode_cgwb_enabled() which determines whether a given inode's both bdi
and fs support cgroup writeback is added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, a wb's (bdi_writeback) congestion state is carried in its
->state field; however, cgroup writeback support will require multiple
wb's sharing the same congestion state. This patch separates out
congestion state into its own struct - struct bdi_writeback_congested.
A new field wb field, wb_congested, points to its associated congested
struct. The default wb, bdi->wb, always points to bdi->wb_congested.
While this patch adds a layer of indirection, it doesn't introduce any
behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Now that bdi definitions are moved to backing-dev-defs.h,
backing-dev.h can include blkdev.h and inline inode_to_bdi() without
worrying about introducing circular include dependency. The function
gets called from hot paths and fairly trivial.
This patch makes inode_to_bdi() and sb_is_blkdev_sb() that the
function calls inline. blockdev_superblock and noop_backing_dev_info
are EXPORT_GPL'd to allow the inline functions to be used from
modules.
While at it, make sb_is_blkdev_sb() return bool instead of int.
v2: Fixed typo in description as suggested by Jan.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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With the planned cgroup writeback support, backing-dev related
declarations will be more widely used across block and cgroup;
unfortunately, including backing-dev.h from include/linux/blkdev.h
makes cyclic include dependency quite likely.
This patch separates out backing-dev-defs.h which only has the
essential definitions and updates blkdev.h to include it. c files
which need access to more backing-dev details now include
backing-dev.h directly. This takes backing-dev.h off the common
include dependency chain making it a lot easier to use it across block
and cgroup.
v2: fs/fat build failure fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.
This patch moves bdi->wb_lock and ->worklist into wb.
* The lock protects bdi->worklist and bdi->wb.dwork scheduling. While
moving, rename it to wb->work_lock as wb->wb_lock is confusing.
Also, move wb->dwork downwards so that it's colocated with the new
->work_lock and ->work_list fields.
* bdi_writeback_workfn() -> wb_workfn()
bdi_wakeup_thread_delayed(bdi) -> wb_wakeup_delayed(wb)
bdi_wakeup_thread(bdi) -> wb_wakeup(wb)
bdi_queue_work(bdi, ...) -> wb_queue_work(wb, ...)
__bdi_start_writeback(bdi, ...) -> __wb_start_writeback(wb, ...)
get_next_work_item(bdi) -> get_next_work_item(wb)
* bdi_wb_shutdown() is renamed to wb_shutdown() and now takes @wb.
The function contained parts which belong to the containing bdi
rather than the wb itself - testing cap_writeback_dirty and
bdi_remove_from_list() invocation. Those are moved to
bdi_unregister().
* bdi_wb_{init|exit}() are renamed to wb_{init|exit}().
Initializations of the moved bdi->wb_lock and ->work_list are
relocated from bdi_init() to wb_init().
* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->state are mechanically replaced with bdi->wb.state
introducing no behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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bdi_writeback
Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.
This patch moves bandwidth related fields from backing_dev_info into
bdi_writeback.
* The moved fields are: bw_time_stamp, dirtied_stamp, written_stamp,
write_bandwidth, avg_write_bandwidth, dirty_ratelimit,
balanced_dirty_ratelimit, completions and dirty_exceeded.
* writeback_chunk_size() and over_bground_thresh() now take @wb
instead of @bdi.
* bdi_writeout_fraction(bdi, ...) -> wb_writeout_fraction(wb, ...)
bdi_dirty_limit(bdi, ...) -> wb_dirty_limit(wb, ...)
bdi_position_ration(bdi, ...) -> wb_position_ratio(wb, ...)
bdi_update_writebandwidth(bdi, ...) -> wb_update_write_bandwidth(wb, ...)
[__]bdi_update_bandwidth(bdi, ...) -> [__]wb_update_bandwidth(wb, ...)
bdi_{max|min}_pause(bdi, ...) -> wb_{max|min}_pause(wb, ...)
bdi_dirty_limits(bdi, ...) -> wb_dirty_limits(wb, ...)
* Init/exits of the relocated fields are moved to bdi_wb_init/exit()
respectively. Note that explicit zeroing is dropped in the process
as wb's are cleared in entirety anyway.
* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[]
introducing no behavior changes.
v2: Typo in description fixed as suggested by Jan.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.
This patch moves bdi->bdi_stat[] into wb.
* enum bdi_stat_item is renamed to wb_stat_item and the prefix of all
enums is changed from BDI_ to WB_.
* BDI_STAT_BATCH() -> WB_STAT_BATCH()
* [__]{add|inc|dec|sum}_wb_stat(bdi, ...) -> [__]{add|inc}_wb_stat(wb, ...)
* bdi_stat[_error]() -> wb_stat[_error]()
* bdi_writeout_inc() -> wb_writeout_inc()
* stat init is moved to bdi_wb_init() and bdi_wb_exit() is added and
frees stat.
* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[]
introducing no behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.
This patch moves bdi->state into wb.
* enum bdi_state is renamed to wb_state and the prefix of all enums is
changed from BDI_ to WB_.
* Explicit zeroing of bdi->state is removed without adding zeoring of
wb->state as the whole data structure is zeroed on init anyway.
* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->state are mechanically replaced with bdi->wb.state
introducing no behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: drbd-dev@lists.linbit.com
Cc: Neil Brown <neilb@suse.de>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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bdi_unregister() now contains very little functionality.
It contains a "WARN_ON" if bdi->dev is NULL. This warning is of no
real consequence as bdi->dev isn't needed by anything else in the function,
and it triggers if
blk_cleanup_queue() -> bdi_destroy()
is called before bdi_unregister, which happens since
Commit: 6cd18e711dd8 ("block: destroy bdi before blockdev is unregistered.")
So this isn't wanted.
It also calls bdi_set_min_ratio(). This needs to be called after
writes through the bdi have all been flushed, and before the bdi is destroyed.
Calling it early is better than calling it late as it frees up a global
resource.
Calling it immediately after bdi_wb_shutdown() in bdi_destroy()
perfectly fits these requirements.
So bdi_unregister() can be discarded with the important content moved to
bdi_destroy(), as can the
writeback_bdi_unregister
event which is already not used.
Reported-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org (v4.0)
Fixes: c4db59d31e39 ("fs: don't reassign dirty inodes to default_backing_dev_info")
Fixes: 6cd18e711dd8 ("block: destroy bdi before blockdev is unregistered.")
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Nicholas Moulin <nicholas.w.moulin@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull lazytime mount option support from Al Viro:
"Lazytime stuff from tytso"
* 'lazytime' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
ext4: add optimization for the lazytime mount option
vfs: add find_inode_nowait() function
vfs: add support for a lazytime mount option
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Add a new mount option which enables a new "lazytime" mode. This mode
causes atime, mtime, and ctime updates to only be made to the
in-memory version of the inode. The on-disk times will only get
updated when (a) if the inode needs to be updated for some non-time
related change, (b) if userspace calls fsync(), syncfs() or sync(), or
(c) just before an undeleted inode is evicted from memory.
This is OK according to POSIX because there are no guarantees after a
crash unless userspace explicitly requests via a fsync(2) call.
For workloads which feature a large number of random write to a
preallocated file, the lazytime mount option significantly reduces
writes to the inode table. The repeated 4k writes to a single block
will result in undesirable stress on flash devices and SMR disk
drives. Even on conventional HDD's, the repeated writes to the inode
table block will trigger Adjacent Track Interference (ATI) remediation
latencies, which very negatively impact long tail latencies --- which
is a very big deal for web serving tiers (for example).
Google-Bug-Id: 18297052
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Now that default_backing_dev_info is not used for writeback purposes we can
git rid of it easily:
- instead of using it's name for tracing unregistered bdi we just use
"unknown"
- btrfs and ceph can just assign the default read ahead window themselves
like several other filesystems already do.
- we can assign noop_backing_dev_info as the default one in alloc_super.
All filesystems already either assigned their own or
noop_backing_dev_info.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Now that we got rid of the bdi abuse on character devices we can always use
sb->s_bdi to get at the backing_dev_info for a file, except for the block
device special case. Export inode_to_bdi and replace uses of
mapping->backing_dev_info with it to prepare for the removal of
mapping->backing_dev_info.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Since "BDI: Provide backing device capability information [try #3]" the
backing_dev_info structure also provides flags for the kind of mmap
operation available in a nommu environment, which is entirely unrelated
to it's original purpose.
Introduce a new nommu-only file operation to provide this information to
the nommu mmap code instead. Splitting this from the backing_dev_info
structure allows to remove lots of backing_dev_info instance that aren't
otherwise needed, and entirely gets rid of the concept of providing a
backing_dev_info for a character device. It also removes the need for
the mtd_inodefs filesystem.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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This bdi flag isn't too useful - we can determine that a vma is backed by
either swap or shmem trivially in the caller.
This also allows removing the backing_dev_info instaces for swap and shmem
in favor of noop_backing_dev_info.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
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A block_device may be attached to different gendisks and thus
different bdis over time. bdev_inode_switch_bdi() is used to switch
the associated bdi. The function assumes that the inode could be
dirty and transfers it between bdis if so. This is a bit nasty in
that it reaches into bdi internals.
This patch reimplements the function so that it writes out the inode
if dirty. This is a lot simpler and can be implemented without
exposing bdi internals.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Two flags and one bdi_writeback field are no longer used. Remove
them.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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After commit 839a8e8660b6 ("writeback: replace custom worker pool
implementation with unbound workqueue") when device is removed while we
are writing to it we crash in bdi_writeback_workfn() ->
set_worker_desc() because bdi->dev is NULL.
This can happen because even though bdi_unregister() cancels all pending
flushing work, nothing really prevents new ones from being queued from
balance_dirty_pages() or other places.
Fix the problem by clearing BDI_registered bit in bdi_unregister() and
checking it before scheduling of any flushing work.
Fixes: 839a8e8660b6777e7fe4e80af1a048aebe2b5977
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Derek Basehore <dbasehore@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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There were two places where return value from bdi_init was not tested.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The feature prevents mistrusted filesystems (ie: FUSE mounts created by
unprivileged users) to grow a large number of dirty pages before
throttling. For such filesystems balance_dirty_pages always check bdi
counters against bdi limits. I.e. even if global "nr_dirty" is under
"freerun", it's not allowed to skip bdi checks. The only use case for now
is fuse: it sets bdi max_ratio to 1% by default and system administrators
are supposed to expect that this limit won't be exceeded.
The feature is on if a BDI is marked by BDI_CAP_STRICTLIMIT flag. A
filesystem may set the flag when it initializes its BDI.
The problematic scenario comes from the fact that nobody pays attention to
the NR_WRITEBACK_TEMP counter (i.e. number of pages under fuse
writeback). The implementation of fuse writeback releases original page
(by calling end_page_writeback) almost immediately. A fuse request queued
for real processing bears a copy of original page. Hence, if userspace
fuse daemon doesn't finalize write requests in timely manner, an
aggressive mmap writer can pollute virtually all memory by those temporary
fuse page copies. They are carefully accounted in NR_WRITEBACK_TEMP, but
nobody cares.
To make further explanations shorter, let me use "NR_WRITEBACK_TEMP
problem" as a shortcut for "a possibility of uncontrolled grow of amount
of RAM consumed by temporary pages allocated by kernel fuse to process
writeback".
The problem was very easy to reproduce. There is a trivial example
filesystem implementation in fuse userspace distribution: fusexmp_fh.c. I
added "sleep(1);" to the write methods, then recompiled and mounted it.
Then created a huge file on the mount point and run a simple program which
mmap-ed the file to a memory region, then wrote a data to the region. An
hour later I observed almost all RAM consumed by fuse writeback. Since
then some unrelated changes in kernel fuse made it more difficult to
reproduce, but it is still possible now.
Putting this theoretical happens-in-the-lab thing aside, there is another
thing that really hurts real world (FUSE) users. This is write-through
page cache policy FUSE currently uses. I.e. handling write(2), kernel
fuse populates page cache and flushes user data to the server
synchronously. This is excessively suboptimal. Pavel Emelyanov's patches
("writeback cache policy") solve the problem, but they also make resolving
NR_WRITEBACK_TEMP problem absolutely necessary. Otherwise, simply copying
a huge file to a fuse mount would result in memory starvation. Miklos,
the maintainer of FUSE, believes strictlimit feature the way to go.
And eventually putting FUSE topics aside, there is one more use-case for
strictlimit feature. Using a slow USB stick (mass storage) in a machine
with huge amount of RAM installed is a well-known pain. Let's make simple
computations. Assuming 64GB of RAM installed, existing implementation of
balance_dirty_pages will start throttling only after 9.6GB of RAM becomes
dirty (freerun == 15% of total RAM). So, the command "cp 9GB_file
/media/my-usb-storage/" may return in a few seconds, but subsequent
"umount /media/my-usb-storage/" will take more than two hours if effective
throughput of the storage is, to say, 1MB/sec.
After inclusion of strictlimit feature, it will be trivial to add a knob
(e.g. /sys/devices/virtual/bdi/x:y/strictlimit) to enable it on demand.
Manually or via udev rule. May be I'm wrong, but it seems to be quite a
natural desire to limit the amount of dirty memory for some devices we are
not fully trust (in the sense of sustainable throughput).
[akpm@linux-foundation.org: fix warning in page-writeback.c]
Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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