Functions gfs2_file_read_iter and gfs2_file_write_iter are both
accessing the user buffer to write to or read from while holding the
inode glock. In the most basic scenario, that buffer will not be
resident and it will be mapped to the same file. Accessing the buffer
will trigger a page fault, and gfs2 will deadlock trying to take the
same inode glock again while trying to handle that fault.
Fix that and similar, more complex scenarios by disabling page faults
while accessing user buffers. To make this work, introduce a small
amount of new infrastructure and fix some bugs that didn't trigger so
far, with page faults enabled.
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Merge tag 'gfs2-v5.15-rc5-mmap-fault' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull gfs2 mmap + page fault deadlocks fixes from Andreas Gruenbacher:
"Functions gfs2_file_read_iter and gfs2_file_write_iter are both
accessing the user buffer to write to or read from while holding the
inode glock.
In the most basic deadlock scenario, that buffer will not be resident
and it will be mapped to the same file. Accessing the buffer will
trigger a page fault, and gfs2 will deadlock trying to take the same
inode glock again while trying to handle that fault.
Fix that and similar, more complex scenarios by disabling page faults
while accessing user buffers. To make this work, introduce a small
amount of new infrastructure and fix some bugs that didn't trigger so
far, with page faults enabled"
* tag 'gfs2-v5.15-rc5-mmap-fault' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
gfs2: Fix mmap + page fault deadlocks for direct I/O
iov_iter: Introduce nofault flag to disable page faults
gup: Introduce FOLL_NOFAULT flag to disable page faults
iomap: Add done_before argument to iomap_dio_rw
iomap: Support partial direct I/O on user copy failures
iomap: Fix iomap_dio_rw return value for user copies
gfs2: Fix mmap + page fault deadlocks for buffered I/O
gfs2: Eliminate ip->i_gh
gfs2: Move the inode glock locking to gfs2_file_buffered_write
gfs2: Introduce flag for glock holder auto-demotion
gfs2: Clean up function may_grant
gfs2: Add wrapper for iomap_file_buffered_write
iov_iter: Introduce fault_in_iov_iter_writeable
iov_iter: Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable
gup: Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable}
powerpc/kvm: Fix kvm_use_magic_page
iov_iter: Fix iov_iter_get_pages{,_alloc} page fault return value
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: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
In order to support multi-layer container images, add multiple
device feature to EROFS. Two ways are available to use for now:
- Devices can be mapped into 32-bit global block address space;
- Device ID can be specified with the chunk indexes format.
Note that it assumes no extent would cross device boundary and mkfs
should take care of it seriously.
In the future, a dedicated device manager could be introduced then
thus extra devices can be automatically scanned by UUID as well.
Link: https://lore.kernel.org/r/20211014081010.43485-1-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Gao 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.com
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao 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: Chao Yu <chao@kernel.org>
Signed-off-by: Gao 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: Chao Yu <chao@kernel.org>
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.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.com
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Martin reported an issue that directory read could be hung on the
latest -rc kernel with some certain image. The root cause is that
commit baa2c7c971 ("block: set .bi_max_vecs as actual allocated
vector number") changes .bi_max_vecs behavior. bio->bi_max_vecs
is set as actual allocated vector number rather than the requested
number now.
Let's avoid using .bi_max_vecs completely instead.
Link: https://lore.kernel.org/r/20210306040438.8084-1-hsiangkao@aol.com
Reported-by: Martin DEVERA <devik@eaxlabs.cz>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
[ Gao Xiang: note that <= 5.11 kernels are not impacted. ]
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
It's often inconvenient to use BIO_MAX_PAGES due to min() requiring the
sign to be the same. Introduce bio_max_segs() and change BIO_MAX_PAGES to
be unsigned to make it easier for the users.
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
- use HTTPS links instead of insecure HTTP ones;
- fix crossing page boundary on specific extended inodes;
- remove useless WQ_CPU_INTENSIVE flag for unbound wq;
- minor cleanup.
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Merge tag 'erofs-for-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs
Pull erofs updates from Gao Xiang:
"This cycle mainly addresses an issue out of some extended inode with
designated location, which are not generated by current mkfs but need
to handled at runtime anyway. The others are quite trivial ones.
- use HTTPS links instead of insecure HTTP ones;
- fix crossing page boundary on specific extended inodes;
- remove useless WQ_CPU_INTENSIVE flag for unbound wq;
- minor cleanup"
* tag 'erofs-for-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
erofs: remove WQ_CPU_INTENSIVE flag from unbound wq's
erofs: fold in used-once helper erofs_workgroup_unfreeze_final()
erofs: fix extended inode could cross boundary
erofs: Replace HTTP links with HTTPS ones
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: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200713130944.34419-1-grandmaster@al2klimov.de
Signed-off-by: Gao 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: Kees Cook <keescook@chromium.org>
- Convert to use the new mount apis;
- Some random cleanup patches.
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Merge tag 'erofs-for-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs
Pull erofs updates from Gao Xiang:
"The most interesting part is the new mount api conversion, which is
actually a old patch already pending for several cycles. And the
others are recent trivial cleanups here.
Summary:
- Convert to use the new mount apis
- Some random cleanup patches"
* tag 'erofs-for-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
erofs: suppress false positive last_block warning
erofs: convert to use the new mount fs_context api
erofs: code cleanup by removing ifdef macro surrounding
Use the new readahead operation in erofs
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Acked-by: Gao 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.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As Andrew mentioned, some rare specific gcc versions could report
last_block uninitialized warning. Actually last_block doesn't need
to be uninitialized first from its implementation due to bio == NULL
condition. After a bio is allocated, last_block will be assigned
then.
The detailed analysis is in this thread [1]. So let's silence those
confusing gccs simply.
[1] https://lore.kernel.org/r/20200421072839.GA13867@hsiangkao-HP-ZHAN-66-Pro-G1
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200528084844.23359-1-hsiangkao@redhat.com
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
After doing more drop_caches stress test on
our products, I found the mistake introduced by
a very recent cleanup [1].
The current rule is that "erofs_get_meta_page"
should be returned with page locked (although
it's mostly unnecessary for read-only fs after
pages are PG_uptodate), but a fix should be
done for this.
[1] https://lore.kernel.org/r/20190904020912.63925-26-gaoxiang25@huawei.com
Fixes: 618f40ea02 ("erofs: use read_cache_page_gfp for erofs_get_meta_page")
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190921184355.149928-1-gaoxiang25@huawei.com
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
As Christoph said [1], "I'd much prefer to just use
read_cache_page_gfp, and live with the fact that this
allocates bufferheads behind you for now. I'll try to
speed up my attempts to get rid of the buffer heads on
the block device mapping instead. "
This simplifies the code a lot and a minor thing is
"no REQ_META (e.g. for blktrace) on metadata at all..."
[1] https://lore.kernel.org/r/20190903153704.GA2201@infradead.org/
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-26-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-23-gaoxiang25@huawei.com
Signed-off-by: Greg 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: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-18-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As Christoph pointed out [1],
"Why is there __erofs_get_meta_page with the two weird
booleans instead of a single erofs_get_meta_page that
gets and gfp_t for additional flags and an unsigned int
for additional bio op flags."
And since all callers can handle errors, let's kill
prio and nofail and erofs_get_inline_page() now.
[1] https://lore.kernel.org/r/20190830162812.GA10694@infradead.org/
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-17-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As Joe Perches suggested [1],
err = bio_add_page(bio, page, PAGE_SIZE, 0);
- if (unlikely(err != PAGE_SIZE)) {
+ if (err != PAGE_SIZE) {
err = -EFAULT;
goto err_out;
}
The initial assignment to err is odd as it's not
actually an error value -E<FOO> but a int size
from a unsigned int len.
Here the return is either 0 or PAGE_SIZE.
This would be more legible to me as:
if (bio_add_page(bio, page, PAGE_SIZE, 0) != PAGE_SIZE) {
err = -EFAULT;
goto err_out;
}
[1] https://lore.kernel.org/r/74c4784319b40deabfbaea92468f7e3ef44f1c96.camel@perches.com/
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190829171741.225219-1-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
EROFS filesystem has been merged into linux-staging for a year.
EROFS is designed to be a better solution of saving extra storage
space with guaranteed end-to-end performance for read-only files
with the help of reduced metadata, fixed-sized output compression
and decompression inplace technologies.
In the past year, EROFS was greatly improved by many people as
a staging driver, self-tested, betaed by a large number of our
internal users, successfully applied to almost all in-service
HUAWEI smartphones as the part of EMUI 9.1 and proven to be stable
enough to be moved out of staging.
EROFS is a self-contained filesystem driver. Although there are
still some TODOs to be more generic, we have a dedicated team
actively keeping on working on EROFS in order to make it better
with the evolution of Linux kernel as the other in-kernel filesystems.
As Pavel suggested, it's better to do as one commit since git
can do moves and all histories will be saved in this way.
Let's promote it from staging and enhance it more actively as
a "real" part of kernel for more wider scenarios!
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Pavel Machek <pavel@denx.de>
Cc: David Sterba <dsterba@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Darrick J . Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Richard Weinberger <richard@nod.at>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Miao Xie <miaoxie@huawei.com>
Cc: Li Guifu <bluce.liguifu@huawei.com>
Cc: Fang Wei <fangwei1@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190822213659.5501-1-hsiangkao@aol.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linus Torvalds
Gao Xiang