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e7a3160d092aa4dd7fb2ef23335cb3a98400aec6
1536 Commits
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5abe37954e |
Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o: "Add as a feature case-insensitive directories (the casefold feature) using Unicode 12.1. Also, the usual largish number of cleanups and bug fixes" * tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (25 commits) ext4: export /sys/fs/ext4/feature/casefold if Unicode support is present ext4: fix ext4_show_options for file systems w/o journal unicode: refactor the rule for regenerating utf8data.h docs: ext4.rst: document case-insensitive directories ext4: Support case-insensitive file name lookups ext4: include charset encoding information in the superblock MAINTAINERS: add Unicode subsystem entry unicode: update unicode database unicode version 12.1.0 unicode: introduce test module for normalized utf8 implementation unicode: implement higher level API for string handling unicode: reduce the size of utf8data[] unicode: introduce code for UTF-8 normalization unicode: introduce UTF-8 character database ext4: actually request zeroing of inode table after grow ext4: cond_resched in work-heavy group loops ext4: fix use-after-free race with debug_want_extra_isize ext4: avoid drop reference to iloc.bh twice ext4: ignore e_value_offs for xattrs with value-in-ea-inode ext4: protect journal inode's blocks using block_validity ext4: use BUG() instead of BUG_ON(1) ... |
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e5fef2a973 |
Merge tag 'afs-next-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull AFS updates from David Howells:
"A set of fix and development patches for AFS for 5.2.
Summary:
- Fix the AFS file locking so that sqlite can run on an AFS mount and
also so that firefox and gnome can use a homedir that's mounted
through AFS.
This required emulation of fine-grained locking when the server
will only support whole-file locks and no upgrade/downgrade. Four
modes are provided, settable by mount parameter:
"flock=local" - No reference to the server
"flock=openafs" - Fine-grained locks are local-only, whole-file
locks require sufficient server locks
"flock=strict" - All locks require sufficient server locks
"flock=write" - Always get an exclusive server lock
If the volume is a read-only or backup volume, then flock=local for
that volume.
- Log extra information for a couple of cases where the client mucks
up somehow: AFS vnode with undefined type and dir check failure -
in both cases we seem to end up with unfilled data, but the issues
happen infrequently and are difficult to reproduce at will.
- Implement silly rename for unlink() and rename().
- Set i_blocks so that du can get some information about usage.
- Fix xattr handlers to return the right amount of data and to not
overflow buffers.
- Implement getting/setting raw AFS and YFS ACLs as xattrs"
* tag 'afs-next-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
afs: Implement YFS ACL setting
afs: Get YFS ACLs and information through xattrs
afs: implement acl setting
afs: Get an AFS3 ACL as an xattr
afs: Fix getting the afs.fid xattr
afs: Fix the afs.cell and afs.volume xattr handlers
afs: Calculate i_blocks based on file size
afs: Log more information for "kAFS: AFS vnode with undefined type\n"
afs: Provide mount-time configurable byte-range file locking emulation
afs: Add more tracepoints
afs: Implement sillyrename for unlink and rename
afs: Add directory reload tracepoint
afs: Handle lock rpc ops failing on a file that got deleted
afs: Improve dir check failure reports
afs: Add file locking tracepoints
afs: Further fix file locking
afs: Fix AFS file locking to allow fine grained locks
afs: Calculate lock extend timer from set/extend reply reception
afs: Split wait from afs_make_call()
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d897166d85 |
Merge branch 'work.file' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs 'struct file' related updates from Al Viro: "A bit more of 'this fget() would be better off as fdget()' whack-a-mole + a couple of ->f_count-related cleanups" * 'work.file' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: media: switch to fdget() drm_syncobj: switch to fdget() amdgpu: switch to fdget() don't open-code file_count() fs: drop unused fput_atomic definition |
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400913252d |
Merge branch 'work.mount-syscalls' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull mount ABI updates from Al Viro: "The syscalls themselves, finally. That's not all there is to that stuff, but switching individual filesystems to new methods is fortunately independent from everything else, so e.g. NFS series can go through NFS tree, etc. As those conversions get done, we'll be finally able to get rid of a bunch of duplication in fs/super.c introduced in the beginning of the entire thing. I expect that to be finished in the next window..." * 'work.mount-syscalls' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: vfs: Add a sample program for the new mount API vfs: syscall: Add fspick() to select a superblock for reconfiguration vfs: syscall: Add fsmount() to create a mount for a superblock vfs: syscall: Add fsconfig() for configuring and managing a context vfs: Implement logging through fs_context vfs: syscall: Add fsopen() to prepare for superblock creation Make anon_inodes unconditional teach move_mount(2) to work with OPEN_TREE_CLONE vfs: syscall: Add move_mount(2) to move mounts around vfs: syscall: Add open_tree(2) to reference or clone a mount |
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52ae2456d6 |
Merge tag 'for-5.2/io_uring-20190507' of git://git.kernel.dk/linux-block
Pull io_uring updates from Jens Axboe: "Set of changes/improvements for io_uring. This contains: - Fix of a shadowed variable (Colin) - Add support for draining commands (me) - Add support for sync_file_range() (me) - Add eventfd support (me) - cpu_online() fix (Shenghui) - Removal of a redundant ->error assignment (Stefan)" * tag 'for-5.2/io_uring-20190507' of git://git.kernel.dk/linux-block: io_uring: use cpu_online() to check p->sq_thread_cpu instead of cpu_possible() io_uring: fix shadowed variable ret return code being not checked req->error only used for iopoll io_uring: add support for eventfd notifications io_uring: add support for IORING_OP_SYNC_FILE_RANGE fs: add sync_file_range() helper io_uring: add support for marking commands as draining |
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22f96b3808 |
fs: add sync_file_range() helper
This just pulls out the ksys_sync_file_range() code to work on a struct file instead of an fd, so we can use it elsewhere. Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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fdb0da89f4 |
new inode method: ->free_inode()
A lot of ->destroy_inode() instances end with call_rcu() of a callback that does RCU-delayed part of freeing. Introduce a new method for doing just that, with saner signature. Rules: ->destroy_inode ->free_inode f g immediate call of f(), RCU-delayed call of g() f NULL immediate call of f(), no RCU-delayed calls NULL g RCU-delayed call of g() NULL NULL RCU-delayed default freeing IOW, NULL ->free_inode gives the same behaviour as now. Note that NULL, NULL is equivalent to NULL, free_inode_nonrcu; we could mandate the latter form, but that would have very little benefit beyond making rules a bit more symmetric. It would break backwards compatibility, require extra boilerplate and expected semantics for (NULL, NULL) pair would have no use whatsoever... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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b886ee3e77 |
ext4: Support case-insensitive file name lookups
This patch implements the actual support for case-insensitive file name
lookups in ext4, based on the feature bit and the encoding stored in the
superblock.
A filesystem that has the casefold feature set is able to configure
directories with the +F (EXT4_CASEFOLD_FL) attribute, enabling lookups
to succeed in that directory in a case-insensitive fashion, i.e: match
a directory entry even if the name used by userspace is not a byte per
byte match with the disk name, but is an equivalent case-insensitive
version of the Unicode string. This operation is called a
case-insensitive file name lookup.
The feature is configured as an inode attribute applied to directories
and inherited by its children. This attribute can only be enabled on
empty directories for filesystems that support the encoding feature,
thus preventing collision of file names that only differ by case.
* dcache handling:
For a +F directory, Ext4 only stores the first equivalent name dentry
used in the dcache. This is done to prevent unintentional duplication of
dentries in the dcache, while also allowing the VFS code to quickly find
the right entry in the cache despite which equivalent string was used in
a previous lookup, without having to resort to ->lookup().
d_hash() of casefolded directories is implemented as the hash of the
casefolded string, such that we always have a well-known bucket for all
the equivalencies of the same string. d_compare() uses the
utf8_strncasecmp() infrastructure, which handles the comparison of
equivalent, same case, names as well.
For now, negative lookups are not inserted in the dcache, since they
would need to be invalidated anyway, because we can't trust missing file
dentries. This is bad for performance but requires some leveraging of
the vfs layer to fix. We can live without that for now, and so does
everyone else.
* on-disk data:
Despite using a specific version of the name as the internal
representation within the dcache, the name stored and fetched from the
disk is a byte-per-byte match with what the user requested, making this
implementation 'name-preserving'. i.e. no actual information is lost
when writing to storage.
DX is supported by modifying the hashes used in +F directories to make
them case/encoding-aware. The new disk hashes are calculated as the
hash of the full casefolded string, instead of the string directly.
This allows us to efficiently search for file names in the htree without
requiring the user to provide an exact name.
* Dealing with invalid sequences:
By default, when a invalid UTF-8 sequence is identified, ext4 will treat
it as an opaque byte sequence, ignoring the encoding and reverting to
the old behavior for that unique file. This means that case-insensitive
file name lookup will not work only for that file. An optional bit can
be set in the superblock telling the filesystem code and userspace tools
to enforce the encoding. When that optional bit is set, any attempt to
create a file name using an invalid UTF-8 sequence will fail and return
an error to userspace.
* Normalization algorithm:
The UTF-8 algorithms used to compare strings in ext4 is implemented
lives in fs/unicode, and is based on a previous version developed by
SGI. It implements the Canonical decomposition (NFD) algorithm
described by the Unicode specification 12.1, or higher, combined with
the elimination of ignorable code points (NFDi) and full
case-folding (CF) as documented in fs/unicode/utf8_norm.c.
NFD seems to be the best normalization method for EXT4 because:
- It has a lower cost than NFC/NFKC (which requires
decomposing to NFD as an intermediary step)
- It doesn't eliminate important semantic meaning like
compatibility decompositions.
Although:
- This implementation is not completely linguistic accurate, because
different languages have conflicting rules, which would require the
specialization of the filesystem to a given locale, which brings all
sorts of problems for removable media and for users who use more than
one language.
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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d46966013b |
afs: Add file locking tracepoints
Add two tracepoints for monitoring AFS file locking. Firstly, add one that
follows the operational part:
echo 1 >/sys/kernel/debug/tracing/events/afs/afs_flock_op/enable
And add a second that more follows the event-driven part:
echo 1 >/sys/kernel/debug/tracing/events/afs/afs_flock_ev/enable
Individual file_lock structs seen by afs are tagged with debugging IDs that
are displayed in the trace log to make it easier to see what's going on,
especially as setting the first lock always seems to involve copying the
file_lock twice.
Signed-off-by: David Howells <dhowells@redhat.com>
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1caf7a70a9 |
fs: drop unused fput_atomic definition
commit |
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10dce8af34 |
fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock
Commit |
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a07b200047 |
vfs: syscall: Add open_tree(2) to reference or clone a mount
open_tree(dfd, pathname, flags) Returns an O_PATH-opened file descriptor or an error. dfd and pathname specify the location to open, in usual fashion (see e.g. fstatat(2)). flags should be an OR of some of the following: * AT_PATH_EMPTY, AT_NO_AUTOMOUNT, AT_SYMLINK_NOFOLLOW - same meanings as usual * OPEN_TREE_CLOEXEC - make the resulting descriptor close-on-exec * OPEN_TREE_CLONE or OPEN_TREE_CLONE | AT_RECURSIVE - instead of opening the location in question, create a detached mount tree matching the subtree rooted at location specified by dfd/pathname. With AT_RECURSIVE the entire subtree is cloned, without it - only the part within in the mount containing the location in question. In other words, the same as mount --rbind or mount --bind would've taken. The detached tree will be dissolved on the final close of obtained file. Creation of such detached trees requires the same capabilities as doing mount --bind. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-api@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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7b47a9e7c8 |
Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs mount infrastructure updates from Al Viro: "The rest of core infrastructure; no new syscalls in that pile, but the old parts are switched to new infrastructure. At that point conversions of individual filesystems can happen independently; some are done here (afs, cgroup, procfs, etc.), there's also a large series outside of that pile dealing with NFS (quite a bit of option-parsing stuff is getting used there - it's one of the most convoluted filesystems in terms of mount-related logics), but NFS bits are the next cycle fodder. It got seriously simplified since the last cycle; documentation is probably the weakest bit at the moment - I considered dropping the commit introducing Documentation/filesystems/mount_api.txt (cutting the size increase by quarter ;-), but decided that it would be better to fix it up after -rc1 instead. That pile allows to do followup work in independent branches, which should make life much easier for the next cycle. fs/super.c size increase is unpleasant; there's a followup series that allows to shrink it considerably, but I decided to leave that until the next cycle" * 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits) afs: Use fs_context to pass parameters over automount afs: Add fs_context support vfs: Add some logging to the core users of the fs_context log vfs: Implement logging through fs_context vfs: Provide documentation for new mount API vfs: Remove kern_mount_data() hugetlbfs: Convert to fs_context cpuset: Use fs_context kernfs, sysfs, cgroup, intel_rdt: Support fs_context cgroup: store a reference to cgroup_ns into cgroup_fs_context cgroup1_get_tree(): separate "get cgroup_root to use" into a separate helper cgroup_do_mount(): massage calling conventions cgroup: stash cgroup_root reference into cgroup_fs_context cgroup2: switch to option-by-option parsing cgroup1: switch to option-by-option parsing cgroup: take options parsing into ->parse_monolithic() cgroup: fold cgroup1_mount() into cgroup1_get_tree() cgroup: start switching to fs_context ipc: Convert mqueue fs to fs_context proc: Add fs_context support to procfs ... |
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d1cae94871 |
Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt
Pull fscrypt updates from Eric Biggers:
"First: Ted, Jaegeuk, and I have decided to add me as a co-maintainer
for fscrypt, and we're now using a shared git tree. So we've updated
MAINTAINERS accordingly, and I'm doing the pull request this time.
The actual changes for v5.1 are:
- Remove the fs-specific kconfig options like CONFIG_EXT4_ENCRYPTION
and make fscrypt support for all fscrypt-capable filesystems be
controlled by CONFIG_FS_ENCRYPTION, similar to how CONFIG_QUOTA
works.
- Improve error code for rename() and link() into encrypted
directories.
- Various cleanups"
* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
MAINTAINERS: add Eric Biggers as an fscrypt maintainer
fscrypt: return -EXDEV for incompatible rename or link into encrypted dir
fscrypt: remove filesystem specific build config option
f2fs: use IS_ENCRYPTED() to check encryption status
ext4: use IS_ENCRYPTED() to check encryption status
fscrypt: remove CRYPTO_CTR dependency
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38e7571c07 |
Merge tag 'io_uring-2019-03-06' of git://git.kernel.dk/linux-block
Pull io_uring IO interface from Jens Axboe:
"Second attempt at adding the io_uring interface.
Since the first one, we've added basic unit testing of the three
system calls, that resides in liburing like the other unit tests that
we have so far. It'll take a while to get full coverage of it, but
we're working towards it. I've also added two basic test programs to
tools/io_uring. One uses the raw interface and has support for all the
various features that io_uring supports outside of standard IO, like
fixed files, fixed IO buffers, and polled IO. The other uses the
liburing API, and is a simplified version of cp(1).
This adds support for a new IO interface, io_uring.
io_uring allows an application to communicate with the kernel through
two rings, the submission queue (SQ) and completion queue (CQ) ring.
This allows for very efficient handling of IOs, see the v5 posting for
some basic numbers:
https://lore.kernel.org/linux-block/20190116175003.17880-1-axboe@kernel.dk/
Outside of just efficiency, the interface is also flexible and
extendable, and allows for future use cases like the upcoming NVMe
key-value store API, networked IO, and so on. It also supports async
buffered IO, something that we've always failed to support in the
kernel.
Outside of basic IO features, it supports async polled IO as well.
This particular feature has already been tested at Facebook months ago
for flash storage boxes, with 25-33% improvements. It makes polled IO
actually useful for real world use cases, where even basic flash sees
a nice win in terms of efficiency, latency, and performance. These
boxes were IOPS bound before, now they are not.
This series adds three new system calls. One for setting up an
io_uring instance (io_uring_setup(2)), one for submitting/completing
IO (io_uring_enter(2)), and one for aux functions like registrating
file sets, buffers, etc (io_uring_register(2)). Through the help of
Arnd, I've coordinated the syscall numbers so merge on that front
should be painless.
Jon did a writeup of the interface a while back, which (except for
minor details that have been tweaked) is still accurate. Find that
here:
https://lwn.net/Articles/776703/
Huge thanks to Al Viro for helping getting the reference cycle code
correct, and to Jann Horn for his extensive reviews focused on both
security and bugs in general.
There's a userspace library that provides basic functionality for
applications that don't need or want to care about how to fiddle with
the rings directly. It has helpers to allow applications to easily set
up an io_uring instance, and submit/complete IO through it without
knowing about the intricacies of the rings. It also includes man pages
(thanks to Jeff Moyer), and will continue to grow support helper
functions and features as time progresses. Find it here:
git://git.kernel.dk/liburing
Fio has full support for the raw interface, both in the form of an IO
engine (io_uring), but also with a small test application (t/io_uring)
that can exercise and benchmark the interface"
* tag 'io_uring-2019-03-06' of git://git.kernel.dk/linux-block:
io_uring: add a few test tools
io_uring: allow workqueue item to handle multiple buffered requests
io_uring: add support for IORING_OP_POLL
io_uring: add io_kiocb ref count
io_uring: add submission polling
io_uring: add file set registration
net: split out functions related to registering inflight socket files
io_uring: add support for pre-mapped user IO buffers
block: implement bio helper to add iter bvec pages to bio
io_uring: batch io_kiocb allocation
io_uring: use fget/fput_many() for file references
fs: add fget_many() and fput_many()
io_uring: support for IO polling
io_uring: add fsync support
Add io_uring IO interface
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80201fe175 |
Merge tag 'for-5.1/block-20190302' of git://git.kernel.dk/linux-block
Pull block layer updates from Jens Axboe:
"Not a huge amount of changes in this round, the biggest one is that we
finally have Mings multi-page bvec support merged. Apart from that,
this pull request contains:
- Small series that avoids quiescing the queue for sysfs changes that
match what we currently have (Aleksei)
- Series of bcache fixes (via Coly)
- Series of lightnvm fixes (via Mathias)
- NVMe pull request from Christoph. Nothing major, just SPDX/license
cleanups, RR mp policy (Hannes), and little fixes (Bart,
Chaitanya).
- BFQ series (Paolo)
- Save blk-mq cpu -> hw queue mapping, removing a pointer indirection
for the fast path (Jianchao)
- fops->iopoll() added for async IO polling, this is a feature that
the upcoming io_uring interface will use (Christoph, me)
- Partition scan loop fixes (Dongli)
- mtip32xx conversion from managed resource API (Christoph)
- cdrom registration race fix (Guenter)
- MD pull from Song, two minor fixes.
- Various documentation fixes (Marcos)
- Multi-page bvec feature. This brings a lot of nice improvements
with it, like more efficient splitting, larger IOs can be supported
without growing the bvec table size, and so on. (Ming)
- Various little fixes to core and drivers"
* tag 'for-5.1/block-20190302' of git://git.kernel.dk/linux-block: (117 commits)
block: fix updating bio's front segment size
block: Replace function name in string with __func__
nbd: propagate genlmsg_reply return code
floppy: remove set but not used variable 'q'
null_blk: fix checking for REQ_FUA
block: fix NULL pointer dereference in register_disk
fs: fix guard_bio_eod to check for real EOD errors
blk-mq: use HCTX_TYPE_DEFAULT but not 0 to index blk_mq_tag_set->map
block: optimize bvec iteration in bvec_iter_advance
block: introduce mp_bvec_for_each_page() for iterating over page
block: optimize blk_bio_segment_split for single-page bvec
block: optimize __blk_segment_map_sg() for single-page bvec
block: introduce bvec_nth_page()
iomap: wire up the iopoll method
block: add bio_set_polled() helper
block: wire up block device iopoll method
fs: add an iopoll method to struct file_operations
loop: set GENHD_FL_NO_PART_SCAN after blkdev_reread_part()
loop: do not print warn message if partition scan is successful
block: bounce: make sure that bvec table is updated
...
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b5dd0c658c |
Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton: - some of the rest of MM - various misc things - dynamic-debug updates - checkpatch - some epoll speedups - autofs - rapidio - lib/, lib/lzo/ updates * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (83 commits) samples/mic/mpssd/mpssd.h: remove duplicate header kernel/fork.c: remove duplicated include include/linux/relay.h: fix percpu annotation in struct rchan arch/nios2/mm/fault.c: remove duplicate include unicore32: stop printing the virtual memory layout MAINTAINERS: fix GTA02 entry and mark as orphan mm: create the new vm_fault_t type arm, s390, unicore32: remove oneliner wrappers for memblock_alloc() arch: simplify several early memory allocations openrisc: simplify pte_alloc_one_kernel() sh: prefer memblock APIs returning virtual address microblaze: prefer memblock API returning virtual address powerpc: prefer memblock APIs returning virtual address lib/lzo: separate lzo-rle from lzo lib/lzo: implement run-length encoding lib/lzo: fast 8-byte copy on arm64 lib/lzo: 64-bit CTZ on arm64 lib/lzo: tidy-up ifdefs ipc/sem.c: replace kvmalloc/memset with kvzalloc and use struct_size ipc: annotate implicit fall through ... |
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f1fffbd447 |
linux/fs.h: move member alignment check next to definition of struct filename
Instead of doing this compile-time check in some slightly arbitrary user of struct filename, put it next to the definition. Link: http://lkml.kernel.org/r/20190208203015.29702-3-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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b39a07a5e0 |
Merge tag 'dtype_for_v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull dtype handling cleanups from Jan Kara: "A reworked dtype cleanup patches based on your feedback to the previous version of these. Again the series includes only the generic code and ext2 cleanup as a sample. The plan is to push cleanups for other filesystems separately through respective trees once the generic code lands to reduce the number of conflicts" * tag 'dtype_for_v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: ext2: use common file type conversion fs: common implementation of file type |
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a9519defc7 |
writeback: fix inode cgroup switching comment
Commit |
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84c4e1f89f |
aio: simplify - and fix - fget/fput for io_submit()
Al Viro root-caused a race where the IOCB_CMD_POLL handling of
fget/fput() could cause us to access the file pointer after it had
already been freed:
"In more details - normally IOCB_CMD_POLL handling looks so:
1) io_submit(2) allocates aio_kiocb instance and passes it to
aio_poll()
2) aio_poll() resolves the descriptor to struct file by req->file =
fget(iocb->aio_fildes)
3) aio_poll() sets ->woken to false and raises ->ki_refcnt of that
aio_kiocb to 2 (bumps by 1, that is).
4) aio_poll() calls vfs_poll(). After sanity checks (basically,
"poll_wait() had been called and only once") it locks the queue.
That's what the extra reference to iocb had been for - we know we
can safely access it.
5) With queue locked, we check if ->woken has already been set to
true (by aio_poll_wake()) and, if it had been, we unlock the
queue, drop a reference to aio_kiocb and bugger off - at that
point it's a responsibility to aio_poll_wake() and the stuff
called/scheduled by it. That code will drop the reference to file
in req->file, along with the other reference to our aio_kiocb.
6) otherwise, we see whether we need to wait. If we do, we unlock the
queue, drop one reference to aio_kiocb and go away - eventual
wakeup (or cancel) will deal with the reference to file and with
the other reference to aio_kiocb
7) otherwise we remove ourselves from waitqueue (still under the
queue lock), so that wakeup won't get us. No async activity will
be happening, so we can safely drop req->file and iocb ourselves.
If wakeup happens while we are in vfs_poll(), we are fine - aio_kiocb
won't get freed under us, so we can do all the checks and locking
safely. And we don't touch ->file if we detect that case.
However, vfs_poll() most certainly *does* touch the file it had been
given. So wakeup coming while we are still in ->poll() might end up
doing fput() on that file. That case is not too rare, and usually we
are saved by the still present reference from descriptor table - that
fput() is not the final one.
But if another thread closes that descriptor right after our fget()
and wakeup does happen before ->poll() returns, we are in trouble -
final fput() done while we are in the middle of a method:
Al also wrote a patch to take an extra reference to the file descriptor
to fix this, but I instead suggested we just streamline the whole file
pointer handling by submit_io() so that the generic aio submission code
simply keeps the file pointer around until the aio has completed.
Fixes:
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091141a42e |
fs: add fget_many() and fput_many()
Some uses cases repeatedly get and put references to the same file, but the only exposed interface is doing these one at the time. As each of these entail an atomic inc or dec on a shared structure, that cost can add up. Add fget_many(), which works just like fget(), except it takes an argument for how many references to get on the file. Ditto fput_many(), which can drop an arbitrary number of references to a file. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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2b188cc1bb |
Add io_uring IO interface
The submission queue (SQ) and completion queue (CQ) rings are shared between the application and the kernel. This eliminates the need to copy data back and forth to submit and complete IO. IO submissions use the io_uring_sqe data structure, and completions are generated in the form of io_uring_cqe data structures. The SQ ring is an index into the io_uring_sqe array, which makes it possible to submit a batch of IOs without them being contiguous in the ring. The CQ ring is always contiguous, as completion events are inherently unordered, and hence any io_uring_cqe entry can point back to an arbitrary submission. Two new system calls are added for this: io_uring_setup(entries, params) Sets up an io_uring instance for doing async IO. On success, returns a file descriptor that the application can mmap to gain access to the SQ ring, CQ ring, and io_uring_sqes. io_uring_enter(fd, to_submit, min_complete, flags, sigset, sigsetsize) Initiates IO against the rings mapped to this fd, or waits for them to complete, or both. The behavior is controlled by the parameters passed in. If 'to_submit' is non-zero, then we'll try and submit new IO. If IORING_ENTER_GETEVENTS is set, the kernel will wait for 'min_complete' events, if they aren't already available. It's valid to set IORING_ENTER_GETEVENTS and 'min_complete' == 0 at the same time, this allows the kernel to return already completed events without waiting for them. This is useful only for polling, as for IRQ driven IO, the application can just check the CQ ring without entering the kernel. With this setup, it's possible to do async IO with a single system call. Future developments will enable polled IO with this interface, and polled submission as well. The latter will enable an application to do IO without doing ANY system calls at all. For IRQ driven IO, an application only needs to enter the kernel for completions if it wants to wait for them to occur. Each io_uring is backed by a workqueue, to support buffered async IO as well. We will only punt to an async context if the command would need to wait for IO on the device side. Any data that can be accessed directly in the page cache is done inline. This avoids the slowness issue of usual threadpools, since cached data is accessed as quickly as a sync interface. Sample application: http://git.kernel.dk/cgit/fio/plain/t/io_uring.c Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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d911b4585e |
vfs: Remove kern_mount_data()
The kern_mount_data() isn't used any more so remove it. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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cb50b348c7 |
convenience helpers: vfs_get_super() and sget_fc()
the former is an analogue of mount_{single,nodev} for use in
->get_tree() instances, the latter - analogue of sget() for the
same.
These are fairly similar to the originals, but the callback signature
for sget_fc() is different from sget() ones, so getting bits and
pieces shared would be too convoluted; we might get around to that
later, but for now let's just remember to keep them in sync. They
do live next to each other, and changes in either won't be hard
to spot.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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