When picking up inplace I/O pages, it should be traversed in reverse
order in aligned with the traversal order of file-backed online pages.
Also, index should be updated together when preloading compressed pages.

Previously, only page-sized pclustersize was supported so no problem
at all. Also rename `compressedpages' to `icpage_ptr' to reflect its
functionality.

Link: https://lore.kernel.org/r/20210407043927.10623-5-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Since multiple pcluster sizes could be used at once, the number of
compressed pages will become a variable factor. It's necessary to
introduce slab pools rather than a single slab cache now.

This limits the pclustersize to 1M (Z_EROFS_PCLUSTER_MAX_SIZE), and
get rid of the obsolete EROFS_FS_CLUSTER_PAGE_LIMIT, which has no
use now.

Link: https://lore.kernel.org/r/20210407043927.10623-4-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Formal big pcluster design is actually more powerful / flexable than
the previous thought whose pclustersize was fixed as power-of-2 blocks,
which was obviously inefficient and space-wasting. Instead, pclustersize
can now be set independently for each pcluster, so various pcluster
sizes can also be used together in one file if mkfs wants (for example,
according to data type and/or compression ratio).

Let's get rid of previous physical_clusterbits[] setting (also notice
that corresponding on-disk fields are still 0 for now). Therefore,
head1/2 can be used for at most 2 different algorithms in one file and
again pclustersize is now independent of these.

Link: https://lore.kernel.org/r/20210407043927.10623-2-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

zmap.c: s/correspoinding/corresponding
zdata.c: s/endding/ending

Link: https://lore.kernel.org/r/20210331093920.31923-1-gongruiqi1@huawei.comReported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NRuiqi Gong <gongruiqi1@huawei.com>
Reviewed-by: NGao Xiang <hsiangkao@redhat.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Add a missing case which could cause unnecessary page allocation but
not directly use inplace I/O instead, which increases runtime extra
memory footprint.

The detail is, considering an online file-backed page, the right half
of the page is chosen to be cached (e.g. the end page of a readahead
request) and some of its data doesn't exist in managed cache, so the
pcluster will be definitely kept in the submission chain. (IOWs, it
cannot be decompressed without I/O, e.g., due to the bypass queue).

Currently, DELAYEDALLOC/TRYALLOC cases can be downgraded as NOINPLACE,
and stop online pages from inplace I/O. After this patch, unneeded page
allocations won't be observed in pickup_page_for_submission() then.

Link: https://lore.kernel.org/r/20210321183227.5182-1-hsiangkao@aol.comSigned-off-by: NGao Xiang <hsiangkao@redhat.com>

Sync decompression was introduced to get rid of additional kworker
scheduling overhead. But there is no such overhead in non-atomic
contexts. Therefore, it should be better to turn off sync decompression
to avoid the current thread waiting in z_erofs_runqueue.

Link: https://lore.kernel.org/r/20210317035448.13921-3-huangjianan@oppo.comReviewed-by: NGao Xiang <hsiangkao@redhat.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NHuang Jianan <huangjianan@oppo.com>
Signed-off-by: NGuo Weichao <guoweichao@oppo.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

z_erofs_decompressqueue_endio may not be executed in the atomic
context, for example, when dm-verity is turned on. In this scenario,
data can be decompressed directly to get rid of additional kworker
scheduling overhead.

Link: https://lore.kernel.org/r/20210317035448.13921-2-huangjianan@oppo.comReviewed-by: NGao Xiang <hsiangkao@redhat.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NHuang Jianan <huangjianan@oppo.com>
Signed-off-by: NGuo Weichao <guoweichao@oppo.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Ever since the addition of multipage bio_vecs BIO_MAX_PAGES has been
horribly confusingly misnamed.  Rename it to BIO_MAX_VECS to stop
confusing users of the bio API.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210311110137.1132391-2-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Try to forcely switch to inplace I/O under low memory scenario in
order to avoid direct memory reclaim due to cached page allocation.

Link: https://lore.kernel.org/r/20201209123717.12430-1-hsiangkao@aol.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

simplify try_to_claim_pcluster() by directly using cmpxchg() here
(the retry loop caused more overhead.) Also, move the chain loop
detection in and rename it to z_erofs_try_to_claim_pcluster().

Link: https://lore.kernel.org/r/20201208095834.3133565-3-hsiangkao@redhat.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Previously, it could be some concern to call add_to_page_cache_lru()
with page->mapping == Z_EROFS_MAPPING_STAGING (!= NULL).

In contrast, page->private is used instead now, so partially revert
commit 5ddcee1f ("erofs: get rid of __stagingpage_alloc helper")
with some adaption for simplicity.

Link: https://lore.kernel.org/r/20201208095834.3133565-2-hsiangkao@redhat.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Previously, we played around with magical page->mapping for short-lived
temporary pages since we need to identify different types of pages in
the same pcluster but both invalidated and short-lived temporary pages
can have page->mapping == NULL. It was considered as safe because that
temporary pages are all non-LRU / non-movable pages.

This patch tends to use specific page->private to identify short-lived
pages instead so it won't rely on page->mapping anymore. Details are
described in "compress.h" as well.

Link: https://lore.kernel.org/r/20201208095834.3133565-1-hsiangkao@redhat.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

pcluster should be only set up for all managed pages instead of
temporary pages. Since it currently uses page->mapping to identify,
the impact is minor for now.

[ Update: Vladimir reported the kernel log becomes polluted
  because PAGE_FLAGS_CHECK_AT_FREE flag(s) set if the page
  allocation debug option is enabled. ]

Link: https://lore.kernel.org/r/20201022145724.27284-1-hsiangkao@aol.com
Fixes: 5ddcee1f ("erofs: get rid of __stagingpage_alloc helper")
Cc: <stable@vger.kernel.org> # 5.5+
Tested-by: NVladimir Zapolskiy <vladimir@tuxera.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Let's add REQ_RAHEAD flag so it'd be easier to identify
readahead I/O requests in blktrace.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200919072730.24989-3-hsiangkao@redhat.comSigned-off-by: NGao Xiang <hsiangkao@redhat.com>

should_decompress_synchronously() has one single condition
for now, so fold it instead.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200919072730.24989-2-hsiangkao@redhat.comSigned-off-by: NGao Xiang <hsiangkao@redhat.com>

variable `err' in z_erofs_submit_queue() isn't useful
here, remove it instead.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200919072730.24989-1-hsiangkao@redhat.comSigned-off-by: NGao Xiang <hsiangkao@redhat.com>

After commit 0615090c ("erofs: convert compressed files from
readpages to readahead"), add_to_page_cache_lru() was moved to mm
code, so that in below call path, no page will be cached into
@pagepool list or grabbed from @pagepool list:
- z_erofs_readpage
 - z_erofs_do_read_page
  - preload_compressed_pages
  - erofs_allocpage

Let's get rid of this unneeded @pagepool parameter.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200917011821.22767-1-yuchao0@huawei.comReviewed-by: NGao Xiang <hsiangkao@redhat.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

The documentation [1] says that WQ_CPU_INTENSIVE is "meaningless" for
unbound wq. I remove this flag from places where unbound queue is
allocated. This is supposed to improve code readability.

[1] https://www.kernel.org/doc/html/latest/core-api/workqueue.html#flagsSigned-off-by: NMaksym Planeta <mplaneta@os.inf.tu-dresden.de>
[Gao Xiang: since the original treewide patch [2] hasn't been merged
            yet, handling the EROFS part only for the next cycle. ]
[2] https://lore.kernel.org/r/20200213141823.2174236-1-mplaneta@os.inf.tu-dresden.de
Link: https://lore.kernel.org/r/20200731024049.16495-1-hsiangkao@aol.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
  If not .svg:
    For each line:
      If doesn't contain `\bxmlns\b`:
        For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
	  If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
            If both the HTTP and HTTPS versions
            return 200 OK and serve the same content:
              Replace HTTP with HTTPS.
Reviewed-by: NGao Xiang <hsiangkao@redhat.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NAlexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200713130944.34419-1-grandmaster@al2klimov.deSigned-off-by: NGao Xiang <hsiangkao@redhat.com>

Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.

In preparation for removing[2] the[3] macro[4], remove all remaining
needless uses with the following script:

git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \
	xargs perl -pi -e \
		's/\buninitialized_var\(([^\)]+)\)/\1/g;
		 s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;'

drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid
pathological white-space.

No outstanding warnings were found building allmodconfig with GCC 9.3.0
for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64,
alpha, and m68k.

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5
Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB
Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers
Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs
Signed-off-by: NKees Cook <keescook@chromium.org>

Use the new readahead operation in erofs.
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NWilliam Kucharski <william.kucharski@oracle.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Acked-by: NGao Xiang <gaoxiang25@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Link: http://lkml.kernel.org/r/20200414150233.24495-20-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new readahead operation in erofs
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NWilliam Kucharski <william.kucharski@oracle.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Acked-by: NGao Xiang <gaoxiang25@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Link: http://lkml.kernel.org/r/20200414150233.24495-19-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert the erofs to use new internal mount API as the old one will
be obsoleted and removed.  This allows greater flexibility in
communication of mount parameters between userspace, the VFS and the
filesystem.

See Documentation/filesystems/mount_api.txt for more information.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200529104836.17843-1-hsiangkao@redhat.comSigned-off-by: NGao Xiang <hsiangkao@redhat.com>

XArray has friendly APIs and it will replace the old radix
tree in the near future.

This convert makes use of __xa_cmpxchg when inserting on
a just inserted item by other thread. In detail, instead
of totally looking up again as what we did for the old
radix tree, it will try to legitimize the current in-tree
item in the XArray therefore more effective.

In addition, naming is rather a challenge for non-English
speaker like me. The basic idea of workstn is to provide
a runtime sparse array with items arranged in the physical
block number order. Such items (was called workgroup) can be
used to record compress clusters or for later new features.

However, both workgroup and workstn seem not good names from
whatever point of view, so I'd like to rename them as pslot
and managed_pslots to stand for physical slots. This patch
handles the second as a part of the radix tree convert.

Cc: Matthew Wilcox <willy@infradead.org>
Link: https://lore.kernel.org/r/20200220024642.91529-1-gaoxiang25@huawei.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

A label and extra variables will be eliminated,
which is more cleaner.

Link: https://lore.kernel.org/r/20200121064819.139469-1-gaoxiang25@huawei.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

No need to introduce such separated helper since
cache strategy compile configs were changed into
runtime options instead in v5.4. No logic changes.

Link: https://lore.kernel.org/r/20200121064747.138987-1-gaoxiang25@huawei.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

All workgroups are registered with tag value set to 0, to simplify
erofs_register_workgroup() interface the tag argument can be removed,
if its only value is sent down to the function body.
Signed-off-by: NVladimir Zapolskiy <vladimir@tuxera.com>
Link: https://lore.kernel.org/r/20200102120118.14979-3-vladimir@tuxera.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

It is feasible to simplify erofs_find_workgroup() interface by removing
an unused function argument. While formally the argument is used in the
function itself, its assigned value is ignored on the caller side.
Signed-off-by: NVladimir Zapolskiy <vladimir@tuxera.com>
Link: https://lore.kernel.org/r/20200102120118.14979-2-vladimir@tuxera.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

VLE was an old informal name of fixed-sized output
compression which came from published ATC'19 paper [1].

Drop those old annotations since erofs can handle
all encoded clusters in block-aligned basis, which
is wider than fixed-sized output compression after
larger clustersize feature is fully implemented.

Unaligned encoding won't be considered in EROFS
since it's not friendly to inplace I/O and perhaps
decompression inplace.

a) Fixed-sized output compression with 16KB pcluster:
  ___________________________________
 |xxxxxxxx|xxxxxxxx|xxxxxxxx|xxxxxxxx|
 |___ 0___|___ 1___|___ 2___|___ 3___| physical blocks

b) Block-aligned fixed-sized input compression with
   16KB pcluster:
  ___________________________________
 |xxxxxxxx|xxxxxxxx|xxxxxxxx|xxx00000|
 |___ 0___|___ 1___|___ 2___|___ 3___| physical blocks

c) Block-unaligned fixed-sized input compression with
   16KB compression unit:
  ____________________________________________
 |..xxxxxx|xxxxxxxx|xxxxxxxx|xxxxxxxx|x.......|
 |___ 0___|___ 1___|___ 2___|___ 3___|___ 4___| physical blocks

Refine better names for those as well.

[1] https://www.usenix.org/conference/atc19/presentation/gao

Link: https://lore.kernel.org/r/20191108033733.63919-1-gaoxiang25@huawei.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

For those tasks waiting I/O for sync decompression,
they should be better marked as IO wait state.

Link: https://lore.kernel.org/r/20191008125616.183715-5-gaoxiang25@huawei.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

Previously, both z_erofs_unzip_io and z_erofs_unzip_io_sb
record decompress queues for backend to use.

The only difference is that z_erofs_unzip_io is used for
on-stack sync decompression so that it doesn't have a super
block field (since the caller can pass it in its context),
but it increases complexity with only a pointer saving.

Rename z_erofs_unzip_io to z_erofs_decompressqueue with
a fixed super_block member and kill the other entirely,
and it can fallback to sync decompression if memory
allocation failure.

Link: https://lore.kernel.org/r/20191008125616.183715-4-gaoxiang25@huawei.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

Now open code is much cleaner due to iterative development.

Link: https://lore.kernel.org/r/20191124025217.12345-1-hsiangkao@aol.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

After commit 4279f3f9 ("staging: erofs: turn cache
strategies into mount options"), cache strategies are
changed into mount options rather than old build configs.

Let's kill useless code for obsoleted build options.

Link: https://lore.kernel.org/r/20191008125616.183715-2-gaoxiang25@huawei.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

 - change return value to int since collection is
   already returned within the collector.
 - better function naming.

Link: https://lore.kernel.org/r/20191008125616.183715-1-gaoxiang25@huawei.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>

Fix a recent cleanup patch. noio (bypass) chain is
handled asynchronously against submit chain, therefore
inplace I/O or pagevec cannot be applied to such pages.
Add detailed comment for this as well.

Fixes: 97e86a85 ("staging: erofs: tidy up decompression frontend")
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190922100434.229340-1-gaoxiang25@huawei.comSigned-off-by: NGao Xiang <gaoxiang25@huawei.com>

Add prefix "erofs_" to these functions and print
sb->s_id as a prefix to erofs_{err, info} so that
the user knows which file system is affected.
Reported-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-23-gaoxiang25@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As Christoph suggested [1], "Please just use plain kmalloc
everywhere and let the normal kernel error injection code
take care of injeting any errors."

[1] https://lore.kernel.org/r/20190829102426.GE20598@infradead.org/Reported-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-20-gaoxiang25@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add erofs_ prefix to free_inode, alloc_inode, ...
Reported-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-19-gaoxiang25@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As Christoph pointed out [1], "
Why is there __submit_bio which really just obsfucates
what is going on?  Also why is __submit_bio using
bio_set_op_attrs instead of opencode it as the comment
right next to it asks you to? "

Let's use submit_bio directly instead.

[1] https://lore.kernel.org/r/20190830162812.GA10694@infradead.org/Reported-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-18-gaoxiang25@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As Christoph pointed out [1], "erofs_grab_bio tries to
handle a bio_alloc failure, except that the function will
not actually fail due the mempool backing it."

Sorry about useless code, fix it now and
localize erofs_grab_bio [2].

[1] https://lore.kernel.org/r/20190830162812.GA10694@infradead.org/
[2] https://lore.kernel.org/r/20190902122016.GL15931@infradead.org/Reported-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-16-gaoxiang25@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>