Add a done_before argument to iomap_dio_rw that indicates how much of
the request has already been transferred.  When the request succeeds, we
report that done_before additional bytes were tranferred.  This is
useful for finishing a request asynchronously when part of the request
has already been completed synchronously.

We'll use that to allow iomap_dio_rw to be used with page faults
disabled: when a page fault occurs while submitting a request, we
synchronously complete the part of the request that has already been
submitted.  The caller can then take care of the page fault and call
iomap_dio_rw again for the rest of the request, passing in the number of
bytes already tranferred.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>

Currently, the whole indexes will only be compacted 4B if
compacted_4b_initial > totalidx. So, the calculated compacted_2b
is worthless for that case. It may waste CPU resources.

No need to update compacted_4b_initial as mkfs since it's used to
fulfill the alignment of the 1st compacted_2b pack and would handle
the case above.

We also need to clarify compacted_4b_end here. It's used for the
last lclusters which aren't fitted in the previous compacted_2b
packs.

Some messages are from Xiang.

Link: https://lore.kernel.org/r/20210914035915.1190-1-zbestahu@gmail.comSigned-off-by: NYue Hu <huyue2@yulong.com>
Reviewed-by: NGao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: NChao Yu <chao@kernel.org>
[ Gao Xiang: it's enough to use "compacted_4b_initial < totalidx". ]
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

Unsupported chunk format should be checked with
"if (vi->chunkformat & ~EROFS_CHUNK_FORMAT_ALL)"

Found when checking with 4k-byte blockmap (although currently mkfs
uses inode chunk indexes format by default.)

Link: https://lore.kernel.org/r/20210922095141.233938-1-hsiangkao@linux.alibaba.com
Fixes: c5aa903a ("erofs: support reading chunk-based uncompressed files")
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

Dan reported a new smatch warning [1]
"fs/erofs/inode.c:210 erofs_read_inode() error: double free of 'copied'"

Due to new chunk-based format handling logic, the error path can be
called after kfree(copied).

Set "copied = NULL" after kfree(copied) to fix this.

[1] https://lore.kernel.org/r/202108251030.bELQozR7-lkp@intel.com

Link: https://lore.kernel.org/r/20210825120757.11034-1-hsiangkao@linux.alibaba.com
Fixes: c5aa903a ("erofs: support reading chunk-based uncompressed files")
Reported-by: Nkernel test robot <lkp@intel.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

Add runtime support for chunk-based uncompressed files
described in the previous patch.

Link: https://lore.kernel.org/r/20210820100019.208490-2-hsiangkao@linux.alibaba.comReviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

Currently, uncompressed data except for tail-packing inline is
consecutive on disk.

In order to support chunk-based data deduplication, add a new
corresponding inode data layout.

In the future, the data source of chunks can be either (un)compressed.

Link: https://lore.kernel.org/r/20210820100019.208490-1-hsiangkao@linux.alibaba.comReviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

Add a rcu argument to the ->get_acl() callback to allow
get_cached_acl_rcu() to call the ->get_acl() method in the next patch.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

This adds fiemap support for both uncompressed files and compressed
files by using iomap infrastructure.

Link: https://lore.kernel.org/r/20210813052931.203280-3-hsiangkao@linux.alibaba.comReviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

Previously, there is no need to get the full decompressed length since
EROFS supports partial decompression. However for some other cases
such as fiemap, the full decompressed length is necessary for iomap to
make it work properly.

This patch adds a way to get the full decompressed length. Note that
it takes more metadata overhead and it'd be avoided if possible in the
performance sensitive scenario.

Link: https://lore.kernel.org/r/20210818152231.243691-1-hsiangkao@linux.alibaba.comReviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

The mapping is not used at all, remove it and update related code.

Link: https://lore.kernel.org/r/20210810072416.1392-1-zbestahu@gmail.comReviewed-by: NGao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NYue Hu <huyue2@yulong.com>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

We already have the wrapper function to identify managed page.

Link: https://lore.kernel.org/r/20210810065450.1320-1-zbestahu@gmail.comReviewed-by: NGao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NYue Hu <huyue2@yulong.com>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

Since tail-packing inline has been supported by iomap now, let's
convert all EROFS uncompressed data I/O to iomap, which is pretty
straight-forward.

Link: https://lore.kernel.org/r/20210805003601.183063-4-hsiangkao@linux.alibaba.com
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

DAX is quite useful for some VM use cases in order to save guest
memory extremely with minimal lightweight EROFS.

In order to prepare for such use cases, add preliminary dax support
for non-tailpacking regular files for now.

Tested with the DRAM-emulated PMEM and the EROFS image generated by
"mkfs.erofs -Enoinline_data enwik9.fsdax.img enwik9"

Link: https://lore.kernel.org/r/20210805003601.183063-3-hsiangkao@linux.alibaba.com
Cc: nvdimm@lists.linux.dev
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

Add iomap support for non-tailpacking uncompressed data in order to
support DIO and DAX.

Direct I/O is useful in certain scenarios for uncompressed files.
For example, double pagecache can be avoid by direct I/O when
loop device is used for uncompressed files containing upper layer
compressed filesystem.

This adds iomap DIO support for non-tailpacking cases first and
tail-packing inline files are handled in the follow-up patch.

Link: https://lore.kernel.org/r/20210805003601.183063-2-hsiangkao@linux.alibaba.com
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NHuang Jianan <huangjianan@oppo.com>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

 - Remove my outdated misleading email address;

 - Get rid of all unnecessary trailing newline by accident.

Link: https://lore.kernel.org/r/20210602160634.10757-1-xiang@kernel.orgReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@linux.alibaba.com>

No any behavior to variable occupied in z_erofs_attach_page() which
is only caller to z_erofs_pagevec_enqueue().

Link: https://lore.kernel.org/r/20210419102623.2015-1-zbestahu@gmail.comSigned-off-by: NYue Hu <huyue2@yulong.com>
Reviewed-by: NGao Xiang <xiang@kernel.org>
Signed-off-by: NGao Xiang <xiang@kernel.org>

'ret' will be overwritten to 0 if erofs_sb_has_sb_chksum() return true,
thus 0 will return in some error handling cases. Fix to return negative
error code -EINVAL instead of 0.

Link: https://lore.kernel.org/r/20210519141657.3062715-1-weiyongjun1@huawei.com
Fixes: b858a484 ("erofs: support superblock checksum")
Cc: stable <stable@vger.kernel.org> # 5.5+
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: NGao Xiang <xiang@kernel.org>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <xiang@kernel.org>

If the 1st NONHEAD lcluster of a pcluster isn't CBLKCNT lcluster type
rather than a HEAD or PLAIN type instead, which means its pclustersize
_must_ be 1 lcluster (since its uncompressed size < 2 lclusters),
as illustrated below:

       HEAD     HEAD / PLAIN    lcluster type
   ____________ ____________
  |_:__________|_________:__|   file data (uncompressed)
   .                .
  .____________.
  |____________|                pcluster data (compressed)

Such on-disk case was explained before [1] but missed to be handled
properly in the runtime implementation.

It can be observed if manually generating 1 lcluster-sized pcluster
with 2 lclusters (thus CBLKCNT doesn't exist.) Let's fix it now.

[1] https://lore.kernel.org/r/20210407043927.10623-1-xiang@kernel.org

Link: https://lore.kernel.org/r/20210510064715.29123-1-xiang@kernel.org
Fixes: cec6e93b ("erofs: support parsing big pcluster compress indexes")
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <xiang@kernel.org>

Enable COMPR_CFGS and BIG_PCLUSTER since the implementations are
all settled properly.

Link: https://lore.kernel.org/r/20210407043927.10623-11-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Prior to big pcluster, there was only one compressed page so it'd
easy to map this. However, when big pcluster is enabled, more work
needs to be done to handle multiple compressed pages. In detail,

 - (maptype 0) if there is only one compressed page + no need
   to copy inplace I/O, just map it directly what we did before;

 - (maptype 1) if there are more compressed pages + no need to
   copy inplace I/O, vmap such compressed pages instead;

 - (maptype 2) if inplace I/O needs to be copied, use per-CPU
   buffers for decompression then.

Another thing is how to detect inplace decompression is feasable or
not (it's still quite easy for non big pclusters), apart from the
inplace margin calculation, inplace I/O page reusing order is also
needed to be considered for each compressed page. Currently, if the
compressed page is the xth page, it shouldn't be reused as [0 ...
nrpages_out - nrpages_in + x], otherwise a full copy will be triggered.

Although there are some extra optimization ideas for this, I'd like
to make big pcluster work correctly first and obviously it can be
further optimized later since it has nothing with the on-disk format
at all.

Link: https://lore.kernel.org/r/20210407043927.10623-10-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Different from non-compact indexes, several lclusters are packed
as the compact form at once and an unique base blkaddr is stored for
each pack, so each lcluster index would take less space on avarage
(e.g. 2 bytes for COMPACT_2B.) btw, that is also why BIG_PCLUSTER
switch should be consistent for compact head0/1.

Prior to big pcluster, the size of all pclusters was 1 lcluster.
Therefore, when a new HEAD lcluster was scanned, blkaddr would be
bumped by 1 lcluster. However, that way doesn't work anymore for
big pcluster since we actually don't know the compressed size of
pclusters in advance (before reading CBLKCNT lcluster).

So, instead, let blkaddr of each pack be the first pcluster blkaddr
with a valid CBLKCNT, in detail,

 1) if CBLKCNT starts at the pack, this first valid pcluster is
    itself, e.g.
  _____________________________________________________________
 |_CBLKCNT0_|_NONHEAD_| .. |_HEAD_|_CBLKCNT1_| ... |_HEAD_| ...
 ^ = blkaddr base          ^ += CBLKCNT0           ^ += CBLKCNT1

 2) if CBLKCNT doesn't start at the pack, the first valid pcluster
    is the next pcluster, e.g.
  _________________________________________________________
 | NONHEAD_| .. |_HEAD_|_CBLKCNT0_| ... |_HEAD_|_HEAD_| ...
                ^ = blkaddr base        ^ += CBLKCNT0
                                               ^ += 1

When a CBLKCNT is found, blkaddr will be increased by CBLKCNT
lclusters, or a new HEAD is found immediately, bump blkaddr by 1
instead (see the picture above.)

Also noted if CBLKCNT is the end of the pack, instead of storing
delta1 (distance of the next HEAD lcluster) as normal NONHEADs,
it still uses the compressed block count (delta0) since delta1
can be calculated indirectly but the block count can't.

Adjust decoding logic to fit big pcluster compact indexes as well.

Link: https://lore.kernel.org/r/20210407043927.10623-9-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

When INCOMPAT_BIG_PCLUSTER sb feature is enabled, legacy compress indexes
will also have the same on-disk header compact indexes to keep per-file
configurations instead of leaving it zeroed.

If ADVISE_BIG_PCLUSTER is set for a file, CBLKCNT will be loaded for each
pcluster in this file by parsing 1st non-head lcluster.

Link: https://lore.kernel.org/r/20210407043927.10623-8-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Adjust per-CPU buffers on demand since big pcluster definition is
available. Also, bail out unsupported pcluster size according to
Z_EROFS_PCLUSTER_MAX_SIZE.

Link: https://lore.kernel.org/r/20210407043927.10623-7-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Big pcluster indicates the size of compressed data for each physical
pcluster is no longer fixed as block size, but could be more than 1
block (more accurately, 1 logical pcluster)

When big pcluster feature is enabled for head0/1, delta0 of the 1st
non-head lcluster index will keep block count of this pcluster in
lcluster size instead of 1. Or, the compressed size of pcluster
should be 1 lcluster if pcluster has no non-head lcluster index.

Also note that BIG_PCLUSTER feature reuses COMPR_CFGS feature since
it depends on COMPR_CFGS and will be released together.

Link: https://lore.kernel.org/r/20210407043927.10623-6-xiang@kernel.orgAcked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

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>

To deal the with the cases which inplace decompression is infeasible
for some inplace I/O. Per-CPU buffers was introduced to get rid of page
allocation latency and thrash for low-latency decompression algorithms
such as lz4.

For the big pcluster feature, introduce multipage per-CPU buffers to
keep such inplace I/O pclusters temporarily as well but note that
per-CPU pages are just consecutive virtually.

When a new big pcluster fs is mounted, its max pclustersize will be
read and per-CPU buffers can be growed if needed. Shrinking adjustable
per-CPU buffers is more complex (because we don't know if such size
is still be used), so currently just release them all when unloading.

Link: https://lore.kernel.org/r/20210409190630.19569-1-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 bitmap for available compression algorithms and a variable-sized
on-disk table for compression options in preparation for upcoming big
pcluster and LZMA algorithm, which follows the end of super block.

To parse the compression options, the bitmap is scanned one by one.
For each available algorithm, there is data followed by 2-byte `length'
correspondingly (it's enough for most cases, or entire fs blocks should
be used.)

With such available algorithm bitmap, kernel itself can also refuse to
mount such filesystem if any unsupported compression algorithm exists.

Note that COMPR_CFGS feature will be enabled with BIG_PCLUSTER.

Link: https://lore.kernel.org/r/20210329100012.12980-1-hsiangkao@aol.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Introduce z_erofs_lz4_cfgs to store all lz4 configurations.
Currently it's only max_distance, but will be used for new
features later.

Link: https://lore.kernel.org/r/20210329012308.28743-4-hsiangkao@aol.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

lz4 uses LZ4_DISTANCE_MAX to record history preservation. When
using rolling decompression, a block with a higher compression
ratio will cause a larger memory allocation (up to 64k). It may
cause a large resource burden in extreme cases on devices with
small memory and a large number of concurrent IOs. So appropriately
reducing this value can improve performance.

Decreasing this value will reduce the compression ratio (except
when input_size <LZ4_DISTANCE_MAX). But considering that erofs
currently only supports 4k output, reducing this value will not
significantly reduce the compression benefits.

The maximum value of LZ4_DISTANCE_MAX defined by lz4 is 64k, and
we can only reduce this value. For the old kernel, it just can't
reduce the memory allocation during rolling decompression without
affecting the decompression result.

Link: https://lore.kernel.org/r/20210329012308.28743-3-hsiangkao@aol.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NHuang Jianan <huangjianan@oppo.com>
Signed-off-by: NGuo Weichao <guoweichao@oppo.com>
[ Gao Xiang: introduce struct erofs_sb_lz4_info for configurations. ]
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Introduce erofs_sb_has_xxx() to make long checks short, especially
for later big pcluster & LZMA features.

Link: https://lore.kernel.org/r/20210329012308.28743-2-hsiangkao@aol.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

If any unknown i_format fields are set (may be of some new incompat
inode features), mark such inode as unsupported.

Just in case of any new incompat i_format fields added in the future.

Link: https://lore.kernel.org/r/20210329003614.6583-1-hsiangkao@aol.com
Fixes: 431339ba ("staging: erofs: add inode operations")
Cc: <stable@vger.kernel.org> # 4.19+
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

Currently, erofs_map_blocks() will be called only from
erofs_{bmap, read_raw_page} which are all for uncompressed files.
So, the compression branch in erofs_map_blocks() is pointless. Let's
remove it and use erofs_map_blocks_flatmode() directly. Also update
related comments.

Link: https://lore.kernel.org/r/20210325071008.573-1-zbestahu@gmail.comReviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NYue Hu <huyue2@yulong.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>

Currently, err would be treated as io error. Therefore, it'd be
better to ensure memory allocation during rolling decompression
to avoid such io error.

In the long term, we might consider adding another !Uptodate case
for such case.

Link: https://lore.kernel.org/r/20210316031515.90954-1-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>