Pull btrfs fixes from David Sterba:
"A few fixes for btrfs:

- blkcg accounting problem with compression that could stall writes

- setting up blkcg bio for compression crashes due to NULL bdev
pointer

- fix possible infinite loop in writeback for nocow files (here
possible means almost impossible, 13 things that need to happen to
trigger it)"

* tag 'for-5.5-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
Btrfs: fix infinite loop during nocow writeback due to race
btrfs: fix compressed write bio blkcg attribution
btrfs: punt all bios created in btrfs_submit_compressed_write()

Pull block fixes from Jens Axboe:
"Three fixes in here:

- Fix for a missing split on default memory boundary mask (4G) (Ming)

- Fix for multi-page read bio truncate (Ming)

- Fix for null_blk zone close request handling (Damien)"

* tag 'block-5.5-20200103' of git://git.kernel.dk/linux-block:
null_blk: Fix REQ_OP_ZONE_CLOSE handling
block: fix splitting segments on boundary masks
block: add bio_truncate to fix guard_bio_eod

When starting writeback for a range that covers part of a preallocated
extent, due to a race with writeback for another range that also covers
another part of the same preallocated extent, we can end up in an infinite
loop.

Consider the following example where for inode 280 we have two dirty
ranges:

range A, from 294912 to 303103, 8192 bytes
range B, from 348160 to 438271, 90112 bytes

and we have the following file extent item layout for our inode:

leaf 38895616 gen 24544 total ptrs 29 free space 13820 owner 5
(...)
item 27 key (280 108 200704) itemoff 14598 itemsize 53
extent data disk bytenr 0 nr 0 type 1 (regular)
extent data offset 0 nr 94208 ram 94208
item 28 key (280 108 294912) itemoff 14545 itemsize 53
extent data disk bytenr 10433052672 nr 81920 type 2 (prealloc)
extent data offset 0 nr 81920 ram 81920

Then the following happens:

1) Writeback starts for range B (from 348160 to 438271), execution of
run_delalloc_nocow() starts;

2) The first iteration of run_delalloc_nocow()'s whil loop leaves us at
the extent item at slot 28, pointing to the prealloc extent item
covering the range from 294912 to 376831. This extent covers part of
our range;

3) An ordered extent is created against that extent, covering the file
range from 348160 to 376831 (28672 bytes);

4) We adjust 'cur_offset' to 376832 and move on to the next iteration of
the while loop;

5) The call to btrfs_lookup_file_extent() leaves us at the same leaf,
pointing to slot 29, 1 slot after the last item (the extent item
we processed in the previous iteration);

6) Because we are a slot beyond the last item, we call btrfs_next_leaf(),
which releases the search path before doing a another search for the
last key of the leaf (280 108 294912);

7) Right after btrfs_next_leaf() released the path, and before it did
another search for the last key of the leaf, writeback for the range
A (from 294912 to 303103) completes (it was previously started at
some point);

8) Upon completion of the ordered extent for range A, the prealloc extent
we previously found got split into two extent items, one covering the
range from 294912 to 303103 (8192 bytes), with a type of regular extent
(and no longer prealloc) and another covering the range from 303104 to
376831 (73728 bytes), with a type of prealloc and an offset of 8192
bytes. So our leaf now has the following layout:

leaf 38895616 gen 24544 total ptrs 31 free space 13664 owner 5
(...)
item 27 key (280 108 200704) itemoff 14598 itemsize 53
extent data disk bytenr 0 nr 0 type 1
extent data offset 0 nr 8192 ram 94208
item 28 key (280 108 208896) itemoff 14545 itemsize 53
extent data disk bytenr 10433142784 nr 86016 type 1
extent data offset 0 nr 86016 ram 86016
item 29 key (280 108 294912) itemoff 14492 itemsize 53
extent data disk bytenr 10433052672 nr 81920 type 1
extent data offset 0 nr 8192 ram 81920
item 30 key (280 108 303104) itemoff 14439 itemsize 53
extent data disk bytenr 10433052672 nr 81920 type 2
extent data offset 8192 nr 73728 ram 81920

9) After btrfs_next_leaf() returns, we have our path pointing to that same
leaf and at slot 30, since it has a key we didn't have before and it's
the first key greater then the key that was previously the last key of
the leaf (key (280 108 294912));

10) The extent item at slot 30 covers the range from 303104 to 376831
which is in our target range, so we process it, despite having already
created an ordered extent against this extent for the file range from
348160 to 376831. This is because we skip to the next extent item only
if its end is less than or equals to the start of our delalloc range,
and not less than or equals to the current offset ('cur_offset');

11) As a result we compute 'num_bytes' as:

num_bytes = min(end + 1, extent_end) - cur_offset;
= min(438271 + 1, 376832) - 376832 = 0

12) We then call create_io_em() for a 0 bytes range starting at offset
376832;

13) Then create_io_em() enters an infinite loop because its calls to
btrfs_drop_extent_cache() do nothing due to the 0 length range
passed to it. So no existing extent maps that cover the offset
376832 get removed, and therefore calls to add_extent_mapping()
return -EEXIST, resulting in an infinite loop. This loop from
create_io_em() is the following:

do {
btrfs_drop_extent_cache(BTRFS_I(inode), em->start,
em->start + em->len - 1, 0);
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em, 1);
write_unlock(&em_tree->lock);
/*
* The caller has taken lock_extent(), who could race with us
* to add em?
*/
} while (ret == -EEXIST);

Also, each call to btrfs_drop_extent_cache() triggers a warning because
the start offset passed to it (376832) is smaller then the end offset
(376832 - 1) passed to it by -1, due to the 0 length:

[258532.052621] ------------[ cut here ]------------
[258532.052643] WARNING: CPU: 0 PID: 9987 at fs/btrfs/file.c:602 btrfs_drop_extent_cache+0x3f4/0x590 [btrfs]
(...)
[258532.052672] CPU: 0 PID: 9987 Comm: fsx Tainted: G W 5.4.0-rc7-btrfs-next-64 #1
[258532.052673] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
[258532.052691] RIP: 0010:btrfs_drop_extent_cache+0x3f4/0x590 [btrfs]
(...)
[258532.052695] RSP: 0018:ffffb4be0153f860 EFLAGS: 00010287
[258532.052700] RAX: ffff975b445ee360 RBX: ffff975b44eb3e08 RCX: 0000000000000000
[258532.052700] RDX: 0000000000038fff RSI: 0000000000039000 RDI: ffff975b445ee308
[258532.052700] RBP: 0000000000038fff R08: 0000000000000000 R09: 0000000000000001
[258532.052701] R10: ffff975b513c5c10 R11: 00000000e3c0cfa9 R12: 0000000000039000
[258532.052703] R13: ffff975b445ee360 R14: 00000000ffffffef R15: ffff975b445ee308
[258532.052705] FS: 00007f86a821de80(0000) GS:ffff975b76a00000(0000) knlGS:0000000000000000
[258532.052707] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[258532.052708] CR2: 00007fdacf0f3ab4 CR3: 00000001f9d26002 CR4: 00000000003606f0
[258532.052712] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[258532.052717] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[258532.052717] Call Trace:
[258532.052718] ? preempt_schedule_common+0x32/0x70
[258532.052722] ? ___preempt_schedule+0x16/0x20
[258532.052741] create_io_em+0xff/0x180 [btrfs]
[258532.052767] run_delalloc_nocow+0x942/0xb10 [btrfs]
[258532.052791] btrfs_run_delalloc_range+0x30b/0x520 [btrfs]
[258532.052812] ? find_lock_delalloc_range+0x221/0x250 [btrfs]
[258532.052834] writepage_delalloc+0xe4/0x140 [btrfs]
[258532.052855] __extent_writepage+0x110/0x4e0 [btrfs]
[258532.052876] extent_write_cache_pages+0x21c/0x480 [btrfs]
[258532.052906] extent_writepages+0x52/0xb0 [btrfs]
[258532.052911] do_writepages+0x23/0x80
[258532.052915] __filemap_fdatawrite_range+0xd2/0x110
[258532.052938] btrfs_fdatawrite_range+0x1b/0x50 [btrfs]
[258532.052954] start_ordered_ops+0x57/0xa0 [btrfs]
[258532.052973] ? btrfs_sync_file+0x225/0x490 [btrfs]
[258532.052988] btrfs_sync_file+0x225/0x490 [btrfs]
[258532.052997] __x64_sys_msync+0x199/0x200
[258532.053004] do_syscall_64+0x5c/0x250
[258532.053007] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[258532.053010] RIP: 0033:0x7f86a7dfd760
(...)
[258532.053014] RSP: 002b:00007ffd99af0368 EFLAGS: 00000246 ORIG_RAX: 000000000000001a
[258532.053016] RAX: ffffffffffffffda RBX: 0000000000000ec9 RCX: 00007f86a7dfd760
[258532.053017] RDX: 0000000000000004 RSI: 000000000000836c RDI: 00007f86a8221000
[258532.053019] RBP: 0000000000021ec9 R08: 0000000000000003 R09: 00007f86a812037c
[258532.053020] R10: 0000000000000001 R11: 0000000000000246 R12: 00000000000074a3
[258532.053021] R13: 00007f86a8221000 R14: 000000000000836c R15: 0000000000000001
[258532.053032] irq event stamp: 1653450494
[258532.053035] hardirqs last enabled at (1653450493): [<ffffffff9dec69f9>] _raw_spin_unlock_irq+0x29/0x50
[258532.053037] hardirqs last disabled at (1653450494): [<ffffffff9d4048ea>] trace_hardirqs_off_thunk+0x1a/0x20
[258532.053039] softirqs last enabled at (1653449852): [<ffffffff9e200466>] __do_softirq+0x466/0x6bd
[258532.053042] softirqs last disabled at (1653449845): [<ffffffff9d4c8a0c>] irq_exit+0xec/0x120
[258532.053043] ---[ end trace 8476fce13d9ce20a ]---

Which results in flooding dmesg/syslog since btrfs_drop_extent_cache()
uses WARN_ON() and not WARN_ON_ONCE().

So fix this issue by changing run_delalloc_nocow()'s loop to move to the
next extent item when the current extent item ends at at offset less than
or equals to the current offset instead of the start offset.

Fixes: 80ff385665b7fc ("Btrfs: update nodatacow code v2")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Pull Kbuild fixes from Masahiro Yamada:

- fix build error in usr/gen_initramfs_list.sh

- fix libelf-dev dependency in deb-pkg build

* tag 'kbuild-fixes-v5.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild/deb-pkg: annotate libelf-dev dependency as :native
gen_initramfs_list.sh: fix 'bad variable name' error

In order to match ZBC defined behavior, closing an empty zone must
result in the "empty" zone condition instead of the "closed" condition.

Fixes: da644b2cc1a4 ("null_blk: add zone open, close, and finish support")
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Bio attribution is handled at bio_set_dev() as once we have a device, we
have a corresponding request_queue and then can derive the current css.
In special cases, we want to attribute to bio to someone else. This can
be done by calling bio_associate_blkg_from_css() or
kthread_associate_blkcg() depending on the scenario. Btrfs does this for
compressed writeback as they are handled by kworkers, so the latter can
be done here.

Commit 1a41802701ec ("btrfs: drop bio_set_dev where not needed") removes
early bio_set_dev() calls prior to submit_stripe_bio(). This breaks the
above assumption that we'll have a request_queue when we are doing
association. To fix this, switch to using kthread_associate_blkcg().

Without this, we crash in btrfs/024:

[ 3052.093088] BUG: kernel NULL pointer dereference, address: 0000000000000510
[ 3052.107013] #PF: supervisor read access in kernel mode
[ 3052.107014] #PF: error_code(0x0000) - not-present page
[ 3052.107015] PGD 0 P4D 0
[ 3052.107021] Oops: 0000 [#1] SMP
[ 3052.138904] CPU: 42 PID: 201270 Comm: kworker/u161:0 Kdump: loaded Not tainted 5.5.0-rc1-00062-g4852d8ac90a9 #712
[ 3052.138905] Hardware name: Quanta Tioga Pass Single Side 01-0032211004/Tioga Pass Single Side, BIOS F08_3A18 12/20/2018
[ 3052.138912] Workqueue: btrfs-delalloc btrfs_work_helper
[ 3052.191375] RIP: 0010:bio_associate_blkg_from_css+0x1e/0x3c0
[ 3052.191379] RSP: 0018:ffffc900210cfc90 EFLAGS: 00010282
[ 3052.191380] RAX: 0000000000000000 RBX: ffff88bfe5573c00 RCX: 0000000000000000
[ 3052.191382] RDX: ffff889db48ec2f0 RSI: ffff88bfe5573c00 RDI: ffff889db48ec2f0
[ 3052.191386] RBP: 0000000000000800 R08: 0000000000203bb0 R09: ffff889db16b2400
[ 3052.293364] R10: 0000000000000000 R11: ffff88a07fffde80 R12: ffff889db48ec2f0
[ 3052.293365] R13: 0000000000001000 R14: ffff889de82bc000 R15: ffff889e2b7bdcc8
[ 3052.293367] FS: 0000000000000000(0000) GS:ffff889ffba00000(0000) knlGS:0000000000000000
[ 3052.293368] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 3052.293369] CR2: 0000000000000510 CR3: 0000000002611001 CR4: 00000000007606e0
[ 3052.293370] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 3052.293371] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 3052.293372] PKRU: 55555554
[ 3052.293376] Call Trace:
[ 3052.402552] btrfs_submit_compressed_write+0x137/0x390
[ 3052.402558] submit_compressed_extents+0x40f/0x4c0
[ 3052.422401] btrfs_work_helper+0x246/0x5a0
[ 3052.422408] process_one_work+0x200/0x570
[ 3052.438601] ? process_one_work+0x180/0x570
[ 3052.438605] worker_thread+0x4c/0x3e0
[ 3052.438614] kthread+0x103/0x140
[ 3052.460735] ? process_one_work+0x570/0x570
[ 3052.460737] ? kthread_mod_delayed_work+0xc0/0xc0
[ 3052.460744] ret_from_fork+0x24/0x30

Fixes: 1a41802701ec ("btrfs: drop bio_set_dev where not needed")
Reported-by: Chris Murphy <chris@colorremedies.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Pull thread fixes from Christian Brauner:
"Here are two fixes:

- Panic earlier when global init exits to generate useable coredumps.

Currently, when global init and all threads in its thread-group
have exited we panic via:

do_exit()
-> exit_notify()
-> forget_original_parent()
-> find_child_reaper()

This makes it hard to extract a useable coredump for global init
from a kernel crashdump because by the time we panic exit_mm() will
have already released global init's mm. We now panic slightly
earlier. This has been a problem in certain environments such as
Android.

- Fix a race in assigning and reading taskstats for thread-groups
with more than one thread.

This patch has been waiting for quite a while since people
disagreed on what the correct fix was at first"

* tag 'for-linus-2020-01-03' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
exit: panic before exit_mm() on global init exit
taskstats: fix data-race

Cross compiling the x86 kernel on a non-x86 build machine produces
the following error when CONFIG_UNWINDER_ORC is enabled, regardless
of whether libelf-dev is installed or not.

dpkg-checkbuilddeps: error: Unmet build dependencies: libelf-dev
dpkg-buildpackage: warning: build dependencies/conflicts unsatisfied; aborting
dpkg-buildpackage: warning: (Use -d flag to override.)

Since this is a build time dependency for a build tool, we need to
depend on the native version of libelf-dev so add the appropriate
annotation.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

We ran into a problem with a mpt3sas based controller, where we would
see random (and hard to reproduce) file corruption). The issue seemed
specific to this controller, but wasn't specific to the file system.
After a lot of debugging, we find out that it's caused by segments
spanning a 4G memory boundary. This shouldn't happen, as the default
setting for segment boundary masks is 4G.

Turns out there are two issues in get_max_segment_size():

1) The default segment boundary mask is bypassed

2) The segment start address isn't taken into account when checking
segment boundary limit

Fix these two issues by removing the bypass of the segment boundary
check even if the mask is set to the default value, and taking into
account the actual start address of the request when checking if a
segment needs splitting.

Cc: stable@vger.kernel.org # v5.1+
Reviewed-by: Chris Mason <clm@fb.com>
Tested-by: Chris Mason <clm@fb.com>
Fixes: dcebd755926b ("block: use bio_for_each_bvec() to compute multi-page bvec count")
Signed-off-by: Ming Lei <ming.lei@redhat.com>

Dropped const on the page pointer, ppc page_to_phys() doesn't mark the
page as const...

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Compressed writes happen in the background via kworkers. However, this
causes bios to be attributed to root bypassing any cgroup limits from
the actual writer. We tag the first bio with REQ_CGROUP_PUNT, which will
punt the bio to an appropriate cgroup specific workqueue and attribute
the IO properly. However, if btrfs_submit_compressed_write() creates a
new bio, we don't tag it the same way. Add the appropriate tagging for
subsequent bios.

Fixes: ec39f7696ccfa ("Btrfs: use REQ_CGROUP_PUNT for worker thread submitted bios")
Reviewed-by: Chris Mason <clm@fb.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Pull powerpc fixes from Michael Ellerman:
"Two more powerpc fixes for 5.5:

- One commit to fix a build error when CONFIG_JUMP_LABEL=n,
introduced by our recent fix to is_shared_processor().

- A commit marking some SLB related functions as notrace, as tracing
them triggers warnings.

Thanks to Jason A Donenfeld"

* tag 'powerpc-5.5-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/spinlocks: Include correct header for static key
powerpc/mm: Mark get_slice_psize() & slice_addr_is_low() as notrace

Currently, when global init and all threads in its thread-group have exited
we panic via:
do_exit()
-> exit_notify()
-> forget_original_parent()
-> find_child_reaper()
This makes it hard to extract a useable coredump for global init from a
kernel crashdump because by the time we panic exit_mm() will have already
released global init's mm.
This patch moves the panic futher up before exit_mm() is called. As was the
case previously, we only panic when global init and all its threads in the
thread-group have exited.

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
[christian.brauner@ubuntu.com: fix typo, rewrite commit message]
Link: https://lore.kernel.org/r/1576736993-10121-1-git-send-email-qiwuchen55@gmail.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Prior to commit 858805b336be ("kbuild: add $(BASH) to run scripts with
bash-extension"), this shell script was almost always run by bash since
bash is usually installed on the system by default.

Now, this script is run by sh, which might be a symlink to dash. On such
distributions, the following code emits an error:

local dev=`LC_ALL=C ls -l "${location}"`

You can reproduce the build error, for example by setting
CONFIG_INITRAMFS_SOURCE="/dev".

GEN usr/initramfs_data.cpio.gz
./usr/gen_initramfs_list.sh: 131: local: 1: bad variable name
make[1]: *** [usr/Makefile:61: usr/initramfs_data.cpio.gz] Error 2

This is because `LC_ALL=C ls -l "${location}"` contains spaces.
Surrounding it with double-quotes fixes the error.

Fixes: 858805b336be ("kbuild: add $(BASH) to run scripts with bash-extension")
Reported-by: Jory A. Pratt <anarchy@gentoo.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>