bcache: remove heap-related macros and switch to generic min_heap

Drop the heap-related macros from bcache and replacing them with the
generic min_heap implementation from include/linux. By doing s

bcache: remove heap-related macros and switch to generic min_heap

Drop the heap-related macros from bcache and replacing them with the
generic min_heap implementation from include/linux. By doing so, code
readability is improved by using functions instead of macros. Moreover,
the min_heap implementation in include/linux adopts a bottom-up variation
compared to the textbook version currently used in bcache. This bottom-up
variation allows for approximately 50% reduction in the number of
comparison operations during heap siftdown, without changing the number of
swaps, thus making it more efficient.

Link: https://lkml.kernel.org/ioyfizrzq7w7mjrqcadtzsfgpuntowtjdw5pgn4qhvsdp4mqqg@nrlek5vmisbu
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kuan-Wei Chiu <[email protected]>
Reviewed-by: Ian Rogers <[email protected]>
Acked-by: Coly Li <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Bagas Sanjaya <[email protected]>
Cc: Brian Foster <[email protected]>
Cc: Ching-Chun (Jim) Huang <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Matthew Sakai <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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bcache: fix variable length array abuse in btree_iter

btree_iter is used in two ways: either allocated on the stack with a
fixed size MAX_BSETS, or from a mempool with a dynamic size based on the
sp

bcache: fix variable length array abuse in btree_iter

btree_iter is used in two ways: either allocated on the stack with a
fixed size MAX_BSETS, or from a mempool with a dynamic size based on the
specific cache set. Previously, the struct had a fixed-length array of
size MAX_BSETS which was indexed out-of-bounds for the dynamically-sized
iterators, which causes UBSAN to complain.

This patch uses the same approach as in bcachefs's sort_iter and splits
the iterator into a btree_iter with a flexible array member and a
btree_iter_stack which embeds a btree_iter as well as a fixed-length
data array.

Cc: [email protected]
Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2039368
Signed-off-by: Matthew Mirvish <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

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bcache: use of hlist_count_nodes()

Make use of the newly added hlist_count_nodes().

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Pierre Gondois <pie

bcache: use of hlist_count_nodes()

Make use of the newly added hlist_count_nodes().

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Pierre Gondois <[email protected]>
Acked-by: Coly Li <[email protected]>
Acked-by: Marco Elver <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Cc: Arve Hjønnevåg <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Martijn Coenen <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Todd Kjos <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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bcache: prevent potential division by zero error

In SHOW(), the variable 'n' is of type 'size_t.' While there is a
conditional check to verify that 'n' is not equal to zero before
executing the 'do_

bcache: prevent potential division by zero error

In SHOW(), the variable 'n' is of type 'size_t.' While there is a
conditional check to verify that 'n' is not equal to zero before
executing the 'do_div' macro, concerns arise regarding potential
division by zero error in 64-bit environments.

The concern arises when 'n' is 64 bits in size, greater than zero, and
the lower 32 bits of it are zeros. In such cases, the conditional check
passes because 'n' is non-zero, but the 'do_div' macro casts 'n' to
'uint32_t,' effectively truncating it to its lower 32 bits.
Consequently, the 'n' value becomes zero.

To fix this potential division by zero error and ensure precise
division handling, this commit replaces the 'do_div' macro with
div64_u64(). div64_u64() is designed to work with 64-bit operands,
guaranteeing that division is performed correctly.

This change enhances the robustness of the code, ensuring that division
operations yield accurate results in all scenarios, eliminating the
possibility of division by zero, and improving compatibility across
different 64-bit environments.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Rand Deeb <[email protected]>
Cc: <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

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bcache: dynamically allocate the md-bcache shrinker

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the md-bcache shrinker, so that it can be freed
asynchr

bcache: dynamically allocate the md-bcache shrinker

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the md-bcache shrinker, so that it can be freed
asynchronously via RCU. Then it doesn't need to wait for RCU read-side
critical section when releasing the struct cache_set.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Qi Zheng <[email protected]>
Acked-by: Muchun Song <[email protected]>
Cc: Coly Li <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alyssa Rosenzweig <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Bob Peterson <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Chandan Babu R <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Christian Koenig <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Dai Ngo <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: "Darrick J. Wong" <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jeffle Xu <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Marijn Suijten <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Olga Kornievskaia <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Steven Price <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tomeu Vizoso <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Yue Hu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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bcache: Convert to use sysfs_emit()/sysfs_emit_at() APIs

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
v

bcache: Convert to use sysfs_emit()/sysfs_emit_at() APIs

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.

Signed-off-by: ye xingchen <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

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block: remove QUEUE_FLAG_DISCARD

Just use a non-zero max_discard_sectors as an indicator for discard
support, similar to what is done for write zeroes.

The only places where needs special attention

block: remove QUEUE_FLAG_DISCARD

Just use a non-zero max_discard_sectors as an indicator for discard
support, similar to what is done for write zeroes.

The only places where needs special attention is the RAID5 driver,
which must clear discard support for security reasons by default,
even if the default stacking rules would allow for it.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Martin K. Petersen <[email protected]>
Acked-by: Christoph Böhmwalder <[email protected]> [drbd]
Acked-by: Jan Höppner <[email protected]> [s390]
Acked-by: Coly Li <[email protected]> [bcache]
Acked-by: David Sterba <[email protected]> [btrfs]
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

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bcache: use default_groups in kobj_type

There are currently 2 ways to create a set of sysfs files for a
kobj_type, through the default_attrs field, and the default_groups
field. Move the bcache sys

bcache: use default_groups in kobj_type

There are currently 2 ways to create a set of sysfs files for a
kobj_type, through the default_attrs field, and the default_groups
field. Move the bcache sysfs code to use default_groups field which has
been the preferred way since aa30f47cf666 ("kobject: Add support for
default attribute groups to kobj_type") so that we can soon get rid of
the obsolete default_attrs field.

Cc: Kent Overstreet <[email protected]>
Cc: [email protected]
Acked-by: Coly Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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bcache: remove the backing_dev_name field from struct cached_dev

Just use the %pg format specifier to print the name directly.

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Coly Li <

bcache: remove the backing_dev_name field from struct cached_dev

Just use the %pg format specifier to print the name directly.

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

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bcache: remove bcache device self-defined readahead

For read cache missing, bcache defines a readahead size for the read I/O
request to the backing device for the missing data. This readahead size
i

bcache: remove bcache device self-defined readahead

For read cache missing, bcache defines a readahead size for the read I/O
request to the backing device for the missing data. This readahead size
is initialized to 0, and almost no one uses it to avoid unnecessary read
amplifying onto backing device and write amplifying onto cache device.
Considering upper layer file system code has readahead logic allready
and works fine with readahead_cache_policy sysfile interface, we don't
have to keep bcache self-defined readahead anymore.

This patch removes the bcache self-defined readahead for cache missing
request for backing device, and the readahead sysfs file interfaces are
removed as well.

This is the preparation for next patch to fix potential kernel panic due
to oversized request in a simpler method.

Reported-by: Alexander Ullrich <[email protected]>
Reported-by: Diego Ercolani <[email protected]>
Reported-by: Jan Szubiak <[email protected]>
Reported-by: Marco Rebhan <[email protected]>
Reported-by: Matthias Ferdinand <[email protected]>
Reported-by: Victor Westerhuis <[email protected]>
Reported-by: Vojtech Pavlik <[email protected]>
Reported-and-tested-by: Rolf Fokkens <[email protected]>
Reported-and-tested-by: Thorsten Knabe <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Cc: [email protected]
Cc: Kent Overstreet <[email protected]>
Cc: Nix <[email protected]>
Cc: Takashi Iwai <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

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bcache: Avoid comma separated statements

Use semicolons and braces.

Signed-off-by: Joe Perches <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

bcache: consider the fragmentation when update the writeback rate

Current way to calculate the writeback rate only considered the
dirty sectors, this usually works fine when the fragmentation
is not

bcache: consider the fragmentation when update the writeback rate

Current way to calculate the writeback rate only considered the
dirty sectors, this usually works fine when the fragmentation
is not high, but it will give us unreasonable small rate when
we are under a situation that very few dirty sectors consumed
a lot dirty buckets. In some case, the dirty bucekts can reached
to CUTOFF_WRITEBACK_SYNC while the dirty data(sectors) not even
reached the writeback_percent, the writeback rate will still
be the minimum value (4k), thus it will cause all the writes to be
stucked in a non-writeback mode because of the slow writeback.

We accelerate the rate in 3 stages with different aggressiveness,
the first stage starts when dirty buckets percent reach above
BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW (50), the second is
BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID (57), the third is
BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH (64). By default
the first stage tries to writeback the amount of dirty data
in one bucket (on average) in (1 / (dirty_buckets_percent - 50)) second,
the second stage tries to writeback the amount of dirty data in one bucket
in (1 / (dirty_buckets_percent - 57)) * 100 millisecond, the third
stage tries to writeback the amount of dirty data in one bucket in
(1 / (dirty_buckets_percent - 64)) millisecond.

the initial rate at each stage can be controlled by 3 configurable
parameters writeback_rate_fp_term_{low|mid|high}, they are by default
1, 10, 1000, the hint of IO throughput that these values are trying
to achieve is described by above paragraph, the reason that
I choose those value as default is based on the testing and the
production data, below is some details:

A. When it comes to the low stage, there is still a bit far from the 70
threshold, so we only want to give it a little bit push by setting the
term to 1, it means the initial rate will be 170 if the fragment is 6,
it is calculated by bucket_size/fragment, this rate is very small,
but still much reasonable than the minimum 8.
For a production bcache with unheavy workload, if the cache device
is bigger than 1 TB, it may take hours to consume 1% buckets,
so it is very possible to reclaim enough dirty buckets in this stage,
thus to avoid entering the next stage.

B. If the dirty buckets ratio didn't turn around during the first stage,
it comes to the mid stage, then it is necessary for mid stage
to be more aggressive than low stage, so i choose the initial rate
to be 10 times more than low stage, that means 1700 as the initial
rate if the fragment is 6. This is some normal rate
we usually see for a normal workload when writeback happens
because of writeback_percent.

C. If the dirty buckets ratio didn't turn around during the low and mid
stages, it comes to the third stage, and it is the last chance that
we can turn around to avoid the horrible cutoff writeback sync issue,
then we choose 100 times more aggressive than the mid stage, that
means 170000 as the initial rate if the fragment is 6. This is also
inferred from a production bcache, I've got one week's writeback rate
data from a production bcache which has quite heavy workloads,
again, the writeback is triggered by the writeback percent,
the highest rate area is around 100000 to 240000, so I believe this
kind aggressiveness at this stage is reasonable for production.
And it should be mostly enough because the hint is trying to reclaim
1000 bucket per second, and from that heavy production env,
it is consuming 50 bucket per second on average in one week's data.

Option writeback_consider_fragment is to control whether we want
this feature to be on or off, it's on by default.

Lastly, below is the performance data for all the testing result,
including the data from production env:
https://docs.google.com/document/d/1AmbIEa_2MhB9bqhC3rfga9tp7n9YX9PLn0jSUxscVW0/edit?usp=sharing

Signed-off-by: dongdong tao <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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md/bcache: convert comma to semicolon

Replace a comma between expression statements by a semicolon.

Signed-off-by: Zheng Yongjun <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Si

md/bcache: convert comma to semicolon

Replace a comma between expression statements by a semicolon.

Signed-off-by: Zheng Yongjun <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: check and set sync status on cache's in-memory super block

Currently the cache's sync status is checked and set on cache set's in-
memory partial super block. After removing the embedded str

bcache: check and set sync status on cache's in-memory super block

Currently the cache's sync status is checked and set on cache set's in-
memory partial super block. After removing the embedded struct cache_sb
from cache set and reference cache's in-memory super block from struct
cache_set, the sync status can set and check directly on cache's super
block.

This patch checks and sets the cache sync status directly on cache's
in-memory super block. This is a preparation for later removing embedded
struct cache_sb from struct cache_set.

Signed-off-by: Coly Li <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: only use bucket_bytes() on struct cache

Because struct cache_set and struct cache both have struct cache_sb,
macro bucket_bytes() currently are used on both of them. When removing
the embedd

bcache: only use bucket_bytes() on struct cache

Because struct cache_set and struct cache both have struct cache_sb,
macro bucket_bytes() currently are used on both of them. When removing
the embedded struct cache_sb from struct cache_set, this macro won't be
used on struct cache_set anymore.

This patch unifies all bucket_bytes() usage only on struct cache, this is
one of the preparation to remove the embedded struct cache_sb from
struct cache_set.

Signed-off-by: Coly Li <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: only use block_bytes() on struct cache

Because struct cache_set and struct cache both have struct cache_sb,
therefore macro block_bytes() can be used on both of them. When removing
the embed

bcache: only use block_bytes() on struct cache

Because struct cache_set and struct cache both have struct cache_sb,
therefore macro block_bytes() can be used on both of them. When removing
the embedded struct cache_sb from struct cache_set, this macro won't be
used on struct cache_set anymore.

This patch unifies all block_bytes() usage only on struct cache, this is
one of the preparation to remove the embedded struct cache_sb from
struct cache_set.

Signed-off-by: Coly Li <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: add sysfs file to display feature sets information of cache set

The following three sysfs files are created to display according feature
set information of bcache:
/sys/fs/bcache/<cache set

bcache: add sysfs file to display feature sets information of cache set

The following three sysfs files are created to display according feature
set information of bcache:
/sys/fs/bcache/<cache set UUID>/internal/feature_compat
/sys/fs/bcache/<cache set UUID>/internal/feature_ro_compat
/sys/fs/bcache/<cache set UUID>/internal/feature_incompat
is added by this patch, to display feature sets information of the cache
set.

Now only an incompat feature 'large_bucket' added in bcache, the sysfs
file content is:
[large_bucket]
string large_bucket means the running bcache drive supports incompat
feature 'large_bucket', the wrapping [] means the 'large_bucket' feature
is currently enabled on this cache set.

This patch is ready to display compat and ro_compat features, in future
once bcache code implements such feature sets, the according feature
strings will be displayed in their sysfs files too.

Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: Convert pr_<level> uses to a more typical style

Remove the trailing newline from the define of pr_fmt and add newlines
to the uses.

Miscellanea:

o Convert bch_bkey_dump from multiple uses

bcache: Convert pr_<level> uses to a more typical style

Remove the trailing newline from the define of pr_fmt and add newlines
to the uses.

Miscellanea:

o Convert bch_bkey_dump from multiple uses of pr_err to pr_cont
as the earlier conversion was inappropriate done causing multiple
lines to be emitted where only a single output line was desired
o Use vsprintf extension %pV in bch_cache_set_error to avoid multiple
line output where only a single line output was desired
o Coalesce formats

Fixes: 6ae63e3501c4 ("bcache: replace printk() by pr_*() routines")

Signed-off-by: Joe Perches <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: Use scnprintf() for avoiding potential buffer overflow

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffe

bcache: Use scnprintf() for avoiding potential buffer overflow

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit. Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: add readahead cache policy options via sysfs interface

In year 2007 high performance SSD was still expensive, in order to
save more space for real workload or meta data, the readahead I/Os
f

bcache: add readahead cache policy options via sysfs interface

In year 2007 high performance SSD was still expensive, in order to
save more space for real workload or meta data, the readahead I/Os
for non-meta data was bypassed and not cached on SSD.

In now days, SSD price drops a lot and people can find larger size
SSD with more comfortable price. It is unncessary to alway bypass
normal readahead I/Os to save SSD space for now.

This patch adds options for readahead data cache policies via sysfs
file /sys/block/bcache<N>/readahead_cache_policy, the options are,
- "all": cache all readahead data I/Os.
- "meta-only": only cache meta data, and bypass other regular I/Os.

If users want to make bcache continue to only cache readahead request
for metadata and bypass regular data readahead, please set "meta-only"
to this sysfs file. By default, bcache will back to cache all read-
ahead requests now.

Cc: [email protected]
Signed-off-by: Coly Li <[email protected]>
Acked-by: Eric Wheeler <[email protected]>
Cc: Michael Lyle <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: add idle_max_writeback_rate sysfs interface

For writeback mode, if there is no regular I/O request for a while,
the writeback rate will be set to the maximum value (1TB/s for now).
This is g

bcache: add idle_max_writeback_rate sysfs interface

For writeback mode, if there is no regular I/O request for a while,
the writeback rate will be set to the maximum value (1TB/s for now).
This is good for most of the storage workload, but there are still
people don't what the maximum writeback rate in I/O idle time.

This patch adds a sysfs interface file idle_max_writeback_rate to
permit people to disable maximum writeback rate. Then the minimum
writeback rate can be advised by writeback_rate_minimum in the
bcache device's sysfs interface.

Reported-by: Christian Balzer <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: add cond_resched() in __bch_cache_cmp()

Read /sys/fs/bcache/<uuid>/cacheN/priority_stats can take very long
time with huge cache after long run.

Signed-off-by: Shile Zhang <shile.zhang@linu

bcache: add cond_resched() in __bch_cache_cmp()

Read /sys/fs/bcache/<uuid>/cacheN/priority_stats can take very long
time with huge cache after long run.

Signed-off-by: Shile Zhang <[email protected]>
Tested-by: Heitor Alves de Siqueira <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: Revert "bcache: use sysfs_match_string() instead of __sysfs_match_string()"

This reverts commit 89e0341af082dbc170019f908846f4a424efc86b.

In drivers/md/bcache/sysfs.c:bch_snprint_string_lis

bcache: Revert "bcache: use sysfs_match_string() instead of __sysfs_match_string()"

This reverts commit 89e0341af082dbc170019f908846f4a424efc86b.

In drivers/md/bcache/sysfs.c:bch_snprint_string_list(), NULL pointer at
the end of list is necessary. Remove the NULL from last element of each
lists will cause the following panic,

[ 4340.455652] bcache: register_cache() registered cache device nvme0n1
[ 4340.464603] bcache: register_bdev() registered backing device sdk
[ 4421.587335] bcache: bch_cached_dev_run() cached dev sdk is running already
[ 4421.587348] bcache: bch_cached_dev_attach() Caching sdk as bcache0 on set 354e1d46-d99f-4d8b-870b-078b80dc88a6
[ 5139.247950] general protection fault: 0000 [#1] SMP NOPTI
[ 5139.247970] CPU: 9 PID: 5896 Comm: cat Not tainted 4.12.14-95.29-default #1 SLE12-SP4
[ 5139.247988] Hardware name: HPE ProLiant DL380 Gen10/ProLiant DL380 Gen10, BIOS U30 04/18/2019
[ 5139.248006] task: ffff888fb25c0b00 task.stack: ffff9bbacc704000
[ 5139.248021] RIP: 0010:string+0x21/0x70
[ 5139.248030] RSP: 0018:ffff9bbacc707bf0 EFLAGS: 00010286
[ 5139.248043] RAX: ffffffffa7e432e3 RBX: ffff8881c20da02a RCX: ffff0a00ffffff04
[ 5139.248058] RDX: 3f00656863616362 RSI: ffff8881c20db000 RDI: ffffffffffffffff
[ 5139.248075] RBP: ffff8881c20db000 R08: 0000000000000000 R09: ffff8881c20da02a
[ 5139.248090] R10: 0000000000000004 R11: 0000000000000000 R12: ffff9bbacc707c48
[ 5139.248104] R13: 0000000000000fd6 R14: ffffffffc0665855 R15: ffffffffc0665855
[ 5139.248119] FS: 00007faf253b8700(0000) GS:ffff88903f840000(0000) knlGS:0000000000000000
[ 5139.248137] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 5139.248149] CR2: 00007faf25395008 CR3: 0000000f72150006 CR4: 00000000007606e0
[ 5139.248164] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 5139.248179] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 5139.248193] PKRU: 55555554
[ 5139.248200] Call Trace:
[ 5139.248210] vsnprintf+0x1fb/0x510
[ 5139.248221] snprintf+0x39/0x40
[ 5139.248238] bch_snprint_string_list.constprop.15+0x5b/0x90 [bcache]
[ 5139.248256] __bch_cached_dev_show+0x44d/0x5f0 [bcache]
[ 5139.248270] ? __alloc_pages_nodemask+0xb2/0x210
[ 5139.248284] bch_cached_dev_show+0x2c/0x50 [bcache]
[ 5139.248297] sysfs_kf_seq_show+0xbb/0x190
[ 5139.248308] seq_read+0xfc/0x3c0
[ 5139.248317] __vfs_read+0x26/0x140
[ 5139.248327] vfs_read+0x87/0x130
[ 5139.248336] SyS_read+0x42/0x90
[ 5139.248346] do_syscall_64+0x74/0x160
[ 5139.248358] entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[ 5139.248370] RIP: 0033:0x7faf24eea370
[ 5139.248379] RSP: 002b:00007fff82d03f38 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[ 5139.248395] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007faf24eea370
[ 5139.248411] RDX: 0000000000020000 RSI: 00007faf25396000 RDI: 0000000000000003
[ 5139.248426] RBP: 00007faf25396000 R08: 00000000ffffffff R09: 0000000000000000
[ 5139.248441] R10: 000000007c9d4d41 R11: 0000000000000246 R12: 00007faf25396000
[ 5139.248456] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000fff
[ 5139.248892] Code: ff ff ff 0f 1f 80 00 00 00 00 49 89 f9 48 89 cf 48 c7 c0 e3 32 e4 a7 48 c1 ff 30 48 81 fa ff 0f 00 00 48 0f 46 d0 48 85 ff 74 45 <44> 0f b6 02 48 8d 42 01 45 84 c0 74 38 48 01 fa 4c 89 cf eb 0e

The simplest way to fix is to revert commit 89e0341af082 ("bcache: use
sysfs_match_string() instead of __sysfs_match_string()").

This bug was introduced in Linux v5.2, so this fix only applies to
Linux v5.2 is enough for stable tree maintainer.

Fixes: 89e0341af082 ("bcache: use sysfs_match_string() instead of __sysfs_match_string()")
Cc: [email protected]
Cc: Alexandru Ardelean <[email protected]>
Reported-by: Peifeng Lin <[email protected]>
Acked-by: Alexandru Ardelean <[email protected]>
Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: add reclaimed_journal_buckets to struct cache_set

Now we have counters for how many times jouranl is reclaimed, how many
times cached dirty btree nodes are flushed, but we don't know how man

bcache: add reclaimed_journal_buckets to struct cache_set

Now we have counters for how many times jouranl is reclaimed, how many
times cached dirty btree nodes are flushed, but we don't know how many
jouranl buckets are really reclaimed.

This patch adds reclaimed_journal_buckets into struct cache_set, this
is an increasing only counter, to tell how many journal buckets are
reclaimed since cache set runs. From all these three counters (reclaim,
reclaimed_journal_buckets, flush_write), we can have idea how well
current journal space reclaim code works.

Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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bcache: remove retry_flush_write from struct cache_set

In struct cache_set, retry_flush_write is added for commit c4dc2497d50d
("bcache: fix high CPU occupancy during journal") which is reverted in

bcache: remove retry_flush_write from struct cache_set

In struct cache_set, retry_flush_write is added for commit c4dc2497d50d
("bcache: fix high CPU occupancy during journal") which is reverted in
previous patch.

Now it is useless anymore, and this patch removes it from bcache code.

Signed-off-by: Coly Li <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

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