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Currently, instead of performing a short write,
iomap_file_buffered_write will fail when part of its iov iterator cannot
be read. In contrast, gfs2_file_buffered_write will loop around if it
can read part of the iov iterator, so we can end up in an endless loop.
This should be fixed in iomap_file_buffered_write (and also
generic_perform_write), but this comes a bit late in the 5.16
development cycle, so work around it in the filesystem by
trimming the iov iterator to the known-good size for now.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Only dereference i->iov after establishing that i is of type ITER_IOVEC.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull gfs2 updates from Andreas Gruenbacher:
- Fix a locking order inversion between the inode and iopen glocks in
gfs2_inode_lookup.
- Implement proper queuing of glock holders for glocks that require
instantiation (like reading an inode or bitmap blocks from disk).
Before, multiple glock holders could race with each other and
half-initialized objects could be exposed; the GL_SKIP flag further
exacerbated this problem.
- Fix a rare deadlock between inode lookup / creation and remote delete
work.
- Fix a rare scheduling-while-atomic bug in dlm during glock hash table
walks.
- Various other minor fixes and cleanups.
* tag 'gfs2-v5.15-rc5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2: (21 commits)
gfs2: Fix unused value warning in do_gfs2_set_flags()
gfs2: check context in gfs2_glock_put
gfs2: Fix glock_hash_walk bugs
gfs2: Cancel remote delete work asynchronously
gfs2: set glock object after nq
gfs2: remove RDF_UPTODATE flag
gfs2: Eliminate GIF_INVALID flag
gfs2: fix GL_SKIP node_scope problems
gfs2: split glock instantiation off from do_promote
gfs2: further simplify do_promote
gfs2: re-factor function do_promote
gfs2: Remove 'first' trace_gfs2_promote argument
gfs2: change go_lock to go_instantiate
gfs2: dump glocks from gfs2_consist_OBJ_i
gfs2: dequeue iopen holder in gfs2_inode_lookup error
gfs2: Save ip from gfs2_glock_nq_init
gfs2: Allow append and immutable bits to coexist
gfs2: Switch some BUG_ON to GLOCK_BUG_ON for debug
gfs2: move GL_SKIP check from glops to do_promote
gfs2: Add GL_SKIP holder flag to dump_holder
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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
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Pull block updates from Jens Axboe:
- mq-deadline accounting improvements (Bart)
- blk-wbt timer fix (Andrea)
- Untangle the block layer includes (Christoph)
- Rework the poll support to be bio based, which will enable adding
support for polling for bio based drivers (Christoph)
- Block layer core support for multi-actuator drives (Damien)
- blk-crypto improvements (Eric)
- Batched tag allocation support (me)
- Request completion batching support (me)
- Plugging improvements (me)
- Shared tag set improvements (John)
- Concurrent queue quiesce support (Ming)
- Cache bdev in ->private_data for block devices (Pavel)
- bdev dio improvements (Pavel)
- Block device invalidation and block size improvements (Xie)
- Various cleanups, fixes, and improvements (Christoph, Jackie,
Masahira, Tejun, Yu, Pavel, Zheng, me)
* tag 'for-5.16/block-2021-10-29' of git://git.kernel.dk/linux-block: (174 commits)
blk-mq-debugfs: Show active requests per queue for shared tags
block: improve readability of blk_mq_end_request_batch()
virtio-blk: Use blk_validate_block_size() to validate block size
loop: Use blk_validate_block_size() to validate block size
nbd: Use blk_validate_block_size() to validate block size
block: Add a helper to validate the block size
block: re-flow blk_mq_rq_ctx_init()
block: prefetch request to be initialized
block: pass in blk_mq_tags to blk_mq_rq_ctx_init()
block: add rq_flags to struct blk_mq_alloc_data
block: add async version of bio_set_polled
block: kill DIO_MULTI_BIO
block: kill unused polling bits in __blkdev_direct_IO()
block: avoid extra iter advance with async iocb
block: Add independent access ranges support
blk-mq: don't issue request directly in case that current is to be blocked
sbitmap: silence data race warning
blk-cgroup: synchronize blkg creation against policy deactivation
block: refactor bio_iov_bvec_set()
block: add single bio async direct IO helper
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Coverity complains of an unused value:
CID 119623 (#1 of 1): Unused value (UNUSED_VALUE)
assigned_value: Assigning value -1 to error here, but that stored value is
overwritten before it can be used.
237 error = -EPERM;
Fix it by removing the assignment.
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Before this patch, function do_gfs2_set_flags checked if the append
and immutable flags were being set while already set. If so, error -EPERM
was given. There's no reason why these two flags should be mutually
exclusive, and if you set them separately, you will, in essence, set
one while it is already set. For example:
chattr +a /mnt/gfs2/file1
chattr +i /mnt/gfs2/file1
The first command sets the append-only flag. Since they are additive,
the second command sets the immutable flag AND append-only flag,
since they both coexist in i_diskflags. So the second command should
not return an error. This bug caused xfstests generic/545 to fail.
This patch simply removes the invalid checks.
I also eliminated an unused parm from do_gfs2_set_flags.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Also disable page faults during direct I/O requests and implement a
similar kind of retry logic as in the buffered I/O case.
The retry logic in the direct I/O case differs from the buffered I/O
case in the following way: direct I/O doesn't provide the kinds of
consistency guarantees between concurrent reads and writes that buffered
I/O provides, so once we lose the inode glock while faulting in user
pages, we always resume the operation. We never need to return a
partial read or write.
This locking problem was originally reported by Jan Kara. Linus came up
with the idea of disabling page faults. Many thanks to Al Viro and
Matthew Wilcox for their feedback.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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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>
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In the .read_iter and .write_iter file operations, we're accessing
user-space memory while holding the inode glock. There is a possibility
that the memory is mapped to the same file, in which case we'd recurse
on the same glock.
We could detect and work around this simple case of recursive locking,
but more complex scenarios exist that involve multiple glocks,
processes, and cluster nodes, and working around all of those cases
isn't practical or even possible.
Avoid these kinds of problems by disabling page faults while holding the
inode glock. If a page fault would occur, we either end up with a
partial read or write or with -EFAULT if nothing could be read or
written. In either case, we know that we're not done with the
operation, so we indicate that we're willing to give up the inode glock
and then we fault in the missing pages. If that made us lose the inode
glock, we return a partial read or write. Otherwise, we resume the
operation.
This locking problem was originally reported by Jan Kara. Linus came up
with the idea of disabling page faults. Many thanks to Al Viro and
Matthew Wilcox for their feedback.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Now that gfs2_file_buffered_write is the only remaining user of
ip->i_gh, we can move the glock holder to the stack (or rather, use the
one we already have on the stack); there is no need for keeping the
holder in the inode anymore.
This is slightly complicated by the fact that we're using ip->i_gh for
the statfs inode in gfs2_file_buffered_write as well. Writing to the
statfs inode isn't very common, so allocate the statfs holder
dynamically when needed.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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So far, for buffered writes, we were taking the inode glock in
gfs2_iomap_begin and dropping it in gfs2_iomap_end with the intention of
not holding the inode glock while iomap_write_actor faults in user
pages. It turns out that iomap_write_actor is called inside iomap_begin
... iomap_end, so the user pages were still faulted in while holding the
inode glock and the locking code in iomap_begin / iomap_end was
completely pointless.
Move the locking into gfs2_file_buffered_write instead. We'll take care
of the potential deadlocks due to faulting in user pages while holding a
glock in a subsequent patch.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Add a wrapper around iomap_file_buffered_write. We'll add code for when
the operation needs to be retried here later.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Replace the blk_poll interface that requires the caller to keep a queue
and cookie from the submissions with polling based on the bio.
Polling for the bio itself leads to a few advantages:
- the cookie construction can made entirely private in blk-mq.c
- the caller does not need to remember the request_queue and cookie
separately and thus sidesteps their lifetime issues
- keeping the device and the cookie inside the bio allows to trivially
support polling BIOs remapping by stacking drivers
- a lot of code to propagate the cookie back up the submission path can
be removed entirely.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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As best I can tell, the logic for these has been broken for a long time
(at least before the move to git), such that they never conflict with
anything. Also, nothing checks for these flags and prevented opens or
read/write behavior on the files. They don't seem to do anything.
Given that, we can rip these symbols out of the kernel, and just make
flock(2) return 0 when LOCK_MAND is set in order to preserve existing
behavior.
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
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We added CONFIG_MANDATORY_FILE_LOCKING in 2015, and soon after turned it
off in Fedora and RHEL8. Several other distros have followed suit.
I've heard of one problem in all that time: Someone migrated from an
older distro that supported "-o mand" to one that didn't, and the host
had a fstab entry with "mand" in it which broke on reboot. They didn't
actually _use_ mandatory locking so they just removed the mount option
and moved on.
This patch rips out mandatory locking support wholesale from the kernel,
along with the Kconfig option and the Documentation file. It also
changes the mount code to ignore the "mand" mount option instead of
erroring out, and to throw a big, ugly warning.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
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Split __gfs2_unstuff_inode off from gfs2_unstuff_dinode and clean up the
code a little. All remaining callers now pass NULL as the page argument
of gfs2_unstuff_dinode, so remove that argument.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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In gfs2_page_mkwrite, unstuff inodes before locking the page. That
way, we won't have to pass in the locked page to gfs2_unstuff_inode,
and gfs2_unstuff_inode can look up and lock the page itself.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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We're setting an error number so that block_page_mkwrite_return
translates it into the corresponding VM_FAULT_* code in several places,
but this is getting confusing, so set the VM_FAULT_* codes directly
instead. (No change in functionality.)
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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On filesystems with a block size smaller than PAGE_SIZE and non-empty
files smaller then PAGE_SIZE, gfs2_page_mkwrite could end up allocating
excess blocks beyond the end of the file, similar to fallocate. This
doesn't make sense; fix it.
Reported-by: Bob Peterson <rpeterso@redhat.com>
Fixes: 184b4e60853d ("gfs2: Fix end-of-file handling in gfs2_page_mkwrite")
Cc: stable@vger.kernel.org # v5.5+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Commit 88b631cbfbeb ("gfs2: convert to fileattr") changed the argument list
without updating the description.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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This reverts commit b7f55d928e75557295c1ac280c291b738905b6fb.
As explained by Linus in [*], write faults on a mmap region are reads
from a filesysten point of view, so taking the inode glock exclusively
on write faults is incorrect.
Instead, when a page is marked writable, the .page_mkwrite vm operation
will be called, which is where the exclusive lock taking needs to
happen. I got this wrong because of a broken test case that made me
believe .page_mkwrite isn't getting called when it actually is.
[*] https://lore.kernel.org/lkml/CAHk-=wj8EWr_D65i4oRSj2FTbrc6RdNydNNCGxeabRnwtoU=3Q@mail.gmail.com/
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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When a write fault occurs, we need to take the inode glock of the underlying
inode in exclusive mode. Otherwise, there's no guarantee that the dirty page
will be written back to disk.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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When a direct I/O write falls entirely and falls back to buffered I/O and the
buffered I/O fails, the write failed with return value 0 instead of the error
number reported by the buffered I/O. Fix that.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull gfs2 updates from Andreas Gruenbacher:
- Fix some compiler and kernel-doc warnings
- Various minor cleanups and optimizations
- Add a new sysfs gfs2 status file with some filesystem wide
information
* tag 'gfs2-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
gfs2: Fix fall-through warnings for Clang
gfs2: Fix a number of kernel-doc warnings
gfs2: Make gfs2_setattr_simple static
gfs2: Add new sysfs file for gfs2 status
gfs2: Silence possible null pointer dereference warning
gfs2: Turn gfs2_meta_indirect_buffer into gfs2_meta_buffer
gfs2: Replace gfs2_lblk_to_dblk with gfs2_get_extent
gfs2: Turn gfs2_extent_map into gfs2_{get,alloc}_extent
gfs2: Add new gfs2_iomap_get helper
gfs2: Remove unused variable sb_format
gfs2: Fix dir.c function parameter descriptions
gfs2: Eliminate gh parameter from go_xmote_bh func
gfs2: don't create empty buffers for NO_CREATE
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Use the fileattr API to let the VFS handle locking, permission checking and
conversion.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
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Building the kernel with W=1 results in a number of kernel-doc warnings
like incorrect function names and parameter descriptions. Fix those,
mostly by adding missing parameter descriptions, removing left-over
descriptions, and demoting some less important kernel-doc comments into
regular comments.
Originally proposed by Lee Jones; improved and combined into a single
patch by Andreas.
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Rename the current gfs2_iomap_get and gfs2_iomap_alloc functions to __*.
Add a new gfs2_iomap_get helper that doesn't expose struct metapath.
Rename gfs2_iomap_get_alloc to gfs2_iomap_alloc. Use the new helpers
where they make sense.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull gfs2 updates from Andreas Gruenbacher:
- Log space and revoke accounting rework to fix some failed asserts.
- Local resource group glock sharing for better local performance.
- Add support for version 1802 filesystems: trusted xattr support and
'-o rgrplvb' mounts by default.
- Actually synchronize on the inode glock's FREEING bit during withdraw
("gfs2: fix glock confusion in function signal_our_withdraw").
- Fix parallel recovery of multiple journals ("gfs2: keep bios separate
for each journal").
- Various other bug fixes.
* tag 'gfs2-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2: (49 commits)
gfs2: Don't get stuck with I/O plugged in gfs2_ail1_flush
gfs2: Per-revoke accounting in transactions
gfs2: Rework the log space allocation logic
gfs2: Minor calc_reserved cleanup
gfs2: Use resource group glock sharing
gfs2: Allow node-wide exclusive glock sharing
gfs2: Add local resource group locking
gfs2: Add per-reservation reserved block accounting
gfs2: Rename rs_{free -> requested} and rd_{reserved -> requested}
gfs2: Check for active reservation in gfs2_release
gfs2: Don't search for unreserved space twice
gfs2: Only pass reservation down to gfs2_rbm_find
gfs2: Also reflect single-block allocations in rgd->rd_extfail_pt
gfs2: Recursive gfs2_quota_hold in gfs2_iomap_end
gfs2: Add trusted xattr support
gfs2: Enable rgrplvb for sb_fs_format 1802
gfs2: Don't skip dlm unlock if glock has an lvb
gfs2: Lock imbalance on error path in gfs2_recover_one
gfs2: Move function gfs2_ail_empty_tr
gfs2: Get rid of current_tail()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull idmapped mounts from Christian Brauner:
"This introduces idmapped mounts which has been in the making for some
time. Simply put, different mounts can expose the same file or
directory with different ownership. This initial implementation comes
with ports for fat, ext4 and with Christoph's port for xfs with more
filesystems being actively worked on by independent people and
maintainers.
Idmapping mounts handle a wide range of long standing use-cases. Here
are just a few:
- Idmapped mounts make it possible to easily share files between
multiple users or multiple machines especially in complex
scenarios. For example, idmapped mounts will be used in the
implementation of portable home directories in
systemd-homed.service(8) where they allow users to move their home
directory to an external storage device and use it on multiple
computers where they are assigned different uids and gids. This
effectively makes it possible to assign random uids and gids at
login time.
- It is possible to share files from the host with unprivileged
containers without having to change ownership permanently through
chown(2).
- It is possible to idmap a container's rootfs and without having to
mangle every file. For example, Chromebooks use it to share the
user's Download folder with their unprivileged containers in their
Linux subsystem.
- It is possible to share files between containers with
non-overlapping idmappings.
- Filesystem that lack a proper concept of ownership such as fat can
use idmapped mounts to implement discretionary access (DAC)
permission checking.
- They allow users to efficiently changing ownership on a per-mount
basis without having to (recursively) chown(2) all files. In
contrast to chown (2) changing ownership of large sets of files is
instantenous with idmapped mounts. This is especially useful when
ownership of a whole root filesystem of a virtual machine or
container is changed. With idmapped mounts a single syscall
mount_setattr syscall will be sufficient to change the ownership of
all files.
- Idmapped mounts always take the current ownership into account as
idmappings specify what a given uid or gid is supposed to be mapped
to. This contrasts with the chown(2) syscall which cannot by itself
take the current ownership of the files it changes into account. It
simply changes the ownership to the specified uid and gid. This is
especially problematic when recursively chown(2)ing a large set of
files which is commong with the aforementioned portable home
directory and container and vm scenario.
- Idmapped mounts allow to change ownership locally, restricting it
to specific mounts, and temporarily as the ownership changes only
apply as long as the mount exists.
Several userspace projects have either already put up patches and
pull-requests for this feature or will do so should you decide to pull
this:
- systemd: In a wide variety of scenarios but especially right away
in their implementation of portable home directories.
https://systemd.io/HOME_DIRECTORY/
- container runtimes: containerd, runC, LXD:To share data between
host and unprivileged containers, unprivileged and privileged
containers, etc. The pull request for idmapped mounts support in
containerd, the default Kubernetes runtime is already up for quite
a while now: https://github.com/containerd/containerd/pull/4734
- The virtio-fs developers and several users have expressed interest
in using this feature with virtual machines once virtio-fs is
ported.
- ChromeOS: Sharing host-directories with unprivileged containers.
I've tightly synced with all those projects and all of those listed
here have also expressed their need/desire for this feature on the
mailing list. For more info on how people use this there's a bunch of
talks about this too. Here's just two recent ones:
https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf
https://fosdem.org/2021/schedule/event/containers_idmap/
This comes with an extensive xfstests suite covering both ext4 and
xfs:
https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts
It covers truncation, creation, opening, xattrs, vfscaps, setid
execution, setgid inheritance and more both with idmapped and
non-idmapped mounts. It already helped to discover an unrelated xfs
setgid inheritance bug which has since been fixed in mainline. It will
be sent for inclusion with the xfstests project should you decide to
merge this.
In order to support per-mount idmappings vfsmounts are marked with
user namespaces. The idmapping of the user namespace will be used to
map the ids of vfs objects when they are accessed through that mount.
By default all vfsmounts are marked with the initial user namespace.
The initial user namespace is used to indicate that a mount is not
idmapped. All operations behave as before and this is verified in the
testsuite.
Based on prior discussions we want to attach the whole user namespace
and not just a dedicated idmapping struct. This allows us to reuse all
the helpers that already exist for dealing with idmappings instead of
introducing a whole new range of helpers. In addition, if we decide in
the future that we are confident enough to enable unprivileged users
to setup idmapped mounts the permission checking can take into account
whether the caller is privileged in the user namespace the mount is
currently marked with.
The user namespace the mount will be marked with can be specified by
passing a file descriptor refering to the user namespace as an
argument to the new mount_setattr() syscall together with the new
MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern
of extensibility.
The following conditions must be met in order to create an idmapped
mount:
- The caller must currently have the CAP_SYS_ADMIN capability in the
user namespace the underlying filesystem has been mounted in.
- The underlying filesystem must support idmapped mounts.
- The mount must not already be idmapped. This also implies that the
idmapping of a mount cannot be altered once it has been idmapped.
- The mount must be a detached/anonymous mount, i.e. it must have
been created by calling open_tree() with the OPEN_TREE_CLONE flag
and it must not already have been visible in the filesystem.
The last two points guarantee easier semantics for userspace and the
kernel and make the implementation significantly simpler.
By default vfsmounts are marked with the initial user namespace and no
behavioral or performance changes are observed.
The manpage with a detailed description can be found here:
https://git.kernel.org/brauner/man-pages/c/1d7b902e2875a1ff342e036a9f866a995640aea8
In order to support idmapped mounts, filesystems need to be changed
and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The
patches to convert individual filesystem are not very large or
complicated overall as can be seen from the included fat, ext4, and
xfs ports. Patches for other filesystems are actively worked on and
will be sent out separately. The xfstestsuite can be used to verify
that port has been done correctly.
The mount_setattr() syscall is motivated independent of the idmapped
mounts patches and it's been around since July 2019. One of the most
valuable features of the new mount api is the ability to perform
mounts based on file descriptors only.
Together with the lookup restrictions available in the openat2()
RESOLVE_* flag namespace which we added in v5.6 this is the first time
we are close to hardened and race-free (e.g. symlinks) mounting and
path resolution.
While userspace has started porting to the new mount api to mount
proper filesystems and create new bind-mounts it is currently not
possible to change mount options of an already existing bind mount in
the new mount api since the mount_setattr() syscall is missing.
With the addition of the mount_setattr() syscall we remove this last
restriction and userspace can now fully port to the new mount api,
covering every use-case the old mount api could. We also add the
crucial ability to recursively change mount options for a whole mount
tree, both removing and adding mount options at the same time. This
syscall has been requested multiple times by various people and
projects.
There is a simple tool available at
https://github.com/brauner/mount-idmapped
that allows to create idmapped mounts so people can play with this
patch series. I'll add support for the regular mount binary should you
decide to pull this in the following weeks:
Here's an example to a simple idmapped mount of another user's home
directory:
u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt
u1001@f2-vm:/$ ls -al /home/ubuntu/
total 28
drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 .
drwxr-xr-x 4 root root 4096 Oct 28 04:00 ..
-rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile
-rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ ls -al /mnt/
total 28
drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 .
drwxr-xr-x 29 root root 4096 Oct 28 22:01 ..
-rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile
-rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ touch /mnt/my-file
u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file
u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file
u1001@f2-vm:/$ ls -al /mnt/my-file
-rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file
u1001@f2-vm:/$ ls -al /home/ubuntu/my-file
-rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file
u1001@f2-vm:/$ getfacl /mnt/my-file
getfacl: Removing leading '/' from absolute path names
# file: mnt/my-file
# owner: u1001
# group: u1001
user::rw-
user:u1001:rwx
group::rw-
mask::rwx
other::r--
u1001@f2-vm:/$ getfacl /home/ubuntu/my-file
getfacl: Removing leading '/' from absolute path names
# file: home/ubuntu/my-file
# owner: ubuntu
# group: ubuntu
user::rw-
user:ubuntu:rwx
group::rw-
mask::rwx
other::r--"
* tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits)
xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl
xfs: support idmapped mounts
ext4: support idmapped mounts
fat: handle idmapped mounts
tests: add mount_setattr() selftests
fs: introduce MOUNT_ATTR_IDMAP
fs: add mount_setattr()
fs: add attr_flags_to_mnt_flags helper
fs: split out functions to hold writers
namespace: only take read lock in do_reconfigure_mnt()
mount: make {lock,unlock}_mount_hash() static
namespace: take lock_mount_hash() directly when changing flags
nfs: do not export idmapped mounts
overlayfs: do not mount on top of idmapped mounts
ecryptfs: do not mount on top of idmapped mounts
ima: handle idmapped mounts
apparmor: handle idmapped mounts
fs: make helpers idmap mount aware
exec: handle idmapped mounts
would_dump: handle idmapped mounts
...
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git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull lazytime updates from Jan Kara:
"Cleanups of the lazytime handling in the writeback code making rules
for calling ->dirty_inode() filesystem handlers saner"
* tag 'lazytime_for_v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
ext4: simplify i_state checks in __ext4_update_other_inode_time()
gfs2: don't worry about I_DIRTY_TIME in gfs2_fsync()
fs: improve comments for writeback_single_inode()
fs: drop redundant check from __writeback_single_inode()
fs: clean up __mark_inode_dirty() a bit
fs: pass only I_DIRTY_INODE flags to ->dirty_inode
fs: don't call ->dirty_inode for lazytime timestamp updates
fat: only specify I_DIRTY_TIME when needed in fat_update_time()
fs: only specify I_DIRTY_TIME when needed in generic_update_time()
fs: correctly document the inode dirty flags
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Add a rs_reserved field to struct gfs2_blkreserv to keep track of the number of
blocks reserved by this particular reservation, and a rd_reserved field to
struct gfs2_rgrpd to keep track of the total number of reserved blocks in the
resource group. Those blocks are exclusively reserved, as opposed to the
rs_requested / rd_requested blocks which are tracked in the reservation tree
(rd_rstree) and which can be stolen if necessary.
When making a reservation with gfs2_inplace_reserve, rs_reserved is set to
somewhere between ap->min_target and ap->target depending on the number of free
blocks in the resource group. When allocating blocks with gfs2_alloc_blocks,
rs_reserved is decremented accordingly. Eventually, any reserved but not
consumed blocks are returned to the resource group by gfs2_inplace_release.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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In gfs2_release, check if the inode has an active reservation to avoid
unnecessary lock taking.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.
As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.
Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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The inode_owner_or_capable() helper determines whether the caller is the
owner of the inode or is capable with respect to that inode. Allow it to
handle idmapped mounts. If the inode is accessed through an idmapped
mount it according to the mount's user namespace. Afterwards the checks
are identical to non-idmapped mounts. If the initial user namespace is
passed nothing changes so non-idmapped mounts will see identical
behavior as before.
Similarly, allow the inode_init_owner() helper to handle idmapped
mounts. It initializes a new inode on idmapped mounts by mapping the
fsuid and fsgid of the caller from the mount's user namespace. If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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Pass a set of flags to iomap_dio_rw instead of the boolean
wait_for_completion argument. The IOMAP_DIO_FORCE_WAIT flag
replaces the wait_for_completion, but only needs to be passed
when the iocb isn't synchronous to start with to simplify the
callers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
[djwong: rework xfs_file.c so that we can push iomap changes separately]
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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The I_DIRTY_TIME flag is primary used within the VFS, and there's no
reason for ->fsync() implementations to do anything with it. This is
because when !datasync, the VFS will expire dirty timestamps before
calling ->fsync(). (See vfs_fsync_range().) This turns I_DIRTY_TIME
into I_DIRTY_SYNC.
Therefore, change gfs2_fsync() to not check for I_DIRTY_TIME.
Link: https://lore.kernel.org/r/20210112190253.64307-11-ebiggers@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull gfs2 updates from Andreas Gruenbacher:
- Make sure transactions won't be started recursively in
gfs2_block_zero_range (bug introduced in 5.4 when switching to
iomap_zero_range)
- Fix a glock holder refcount leak introduced in the iopen glock
locking scheme rework merged in 5.8.
- A few other small improvements (debugging, stack usage, comment
fixes).
* tag 'gfs2-for-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
gfs2: When gfs2_dirty_inode gets a glock error, dump the glock
gfs2: Never call gfs2_block_zero_range with an open transaction
gfs2: print details on transactions that aren't properly ended
gfs2: Fix inaccurate comment
fs: Fix typo in comment
gfs2: Fix refcount leak in gfs2_glock_poke
gfs2: Pass glock holder to gfs2_file_direct_{read,write}
gfs2: Add some flags missing from glock output
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Pull iomap updates from Darrick Wong:
"The most notable changes are:
- iomap no longer invalidates the page cache when performing a direct
read, since doing so is unnecessary and the old directio code
doesn't do that either.
- iomap embraced the use of returning ENOTBLK from a direct write to
trigger falling back to a buffered write since ext4 already did
this and btrfs wants it for their port.
- iomap falls back to buffered writes if we're doing a direct write
and the page cache invalidation after the flush fails; this was
necessary to handle a corner case in the btrfs port.
- Remove email virus scanner detritus that was accidentally included
in yesterday's pull request. Clearly I need(ed) to update my git
branch checker scripts. :("
* tag 'iomap-5.9-merge-5' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
iomap: fall back to buffered writes for invalidation failures
xfs: use ENOTBLK for direct I/O to buffered I/O fallback
iomap: Only invalidate page cache pages on direct IO writes
iomap: Make sure iomap_end is called after iomap_begin
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Failing to invalid the page cache means data in incoherent, which is
a very bad state for the system. Always fall back to buffered I/O
through the page cache if we can't invalidate mappings.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu> # for ext4
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com> # for gfs2
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
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Pass a pointer to the existing glock holder from
gfs2_file_{read,write}_iter to gfs2_file_direct_{read,write}
to save some stack space.
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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So far, gfs2 has taken the inode glocks inside the ->readpage and
->readahead address space operations. Since commit d4388340ae0b ("fs:
convert mpage_readpages to mpage_readahead"), gfs2_readahead is passed
the pages to read ahead locked. With that, the current holder of the
inode glock may be trying to lock one of those pages while
gfs2_readahead is trying to take the inode glock, resulting in a
deadlock.
Fix that by moving the lock taking to the higher-level ->read_iter file
and ->fault vm operations. This also gets rid of an ugly lock inversion
workaround in gfs2_readpage.
The cache consistency model of filesystems like gfs2 is such that if
data is found in the page cache, the data is up to date and can be used
without taking any filesystem locks. If a page is not cached,
filesystem locks must be taken before populating the page cache.
To avoid taking the inode glock when the data is already cached,
gfs2_file_read_iter first tries to read the data with the IOCB_NOIO flag
set. If that fails, the inode glock is taken and the operation is
retried with the IOCB_NOIO flag cleared.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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We now get the quota data structure when opening a file writable and put it
when closing that writable file descriptor, so there no longer is a need for
gfs2_qa_{get,put} while we're holding a writable file descriptor.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
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Keeping reservations and quotas separate helps reviewing the code.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
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Before this patch, multiple users called gfs2_qa_alloc which allocated
a qadata structure to the inode, if quotas are turned on. Later, in
file close or evict, the structure was deleted with gfs2_qa_delete.
But there can be several competing processes who need access to the
structure. There were races between file close (release) and the others.
Thus, a release could delete the structure out from under a process
that relied upon its existence. For example, chown.
This patch changes the management of the qadata structures to be
a get/put scheme. Function gfs2_qa_alloc has been changed to gfs2_qa_get
and if the structure is allocated, the count essentially starts out at
1. Function gfs2_qa_delete has been renamed to gfs2_qa_put, and the
last guy to decrement the count to 0 frees the memory.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
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Before this patch, multiple callers called gfs2_rsqa_alloc to force
the existence of a reservations structure and a quota data structure
if needed. However, now the reservations are handled separately, so
the quota data is only the quota data. So we eliminate the one in
favor of just calling gfs2_qa_alloc directly.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
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In gfs2_file_write_iter, for direct writes, the error checking in the buffered
write fallback case is incomplete. This can cause inode write errors to go
undetected. Fix and clean up gfs2_file_write_iter along the way.
Based on a proposed fix by Christoph Hellwig <hch@lst.de>.
Fixes: 967bcc91b044 ("gfs2: iomap direct I/O support")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Set current->backing_dev_info just around the buffered write calls to
prepare for the next fix.
Fixes: 967bcc91b044 ("gfs2: iomap direct I/O support")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull GFS2 updates from Andreas Gruenbacher:
"Bob's extensive filesystem withdrawal and recovery testing:
- don't write log headers after file system withdraw
- clean up iopen glock mess in gfs2_create_inode
- close timing window with GLF_INVALIDATE_IN_PROGRESS
- abort gfs2_freeze if io error is seen
- don't loop forever in gfs2_freeze if withdrawn
- fix infinite loop in gfs2_ail1_flush on io error
- introduce function gfs2_withdrawn
- fix glock reference problem in gfs2_trans_remove_revoke
Filesystems with a block size smaller than the page size:
- fix end-of-file handling in gfs2_page_mkwrite
- improve mmap write vs. punch_hole consistency
Other:
- remove active journal side effect from gfs2_write_log_header
- multi-block allocations in gfs2_page_mkwrite
Minor cleanups and coding style fixes:
- remove duplicate call from gfs2_create_inode
- make gfs2_log_shutdown static
- make gfs2_fs_parameters static
- some whitespace cleanups
- removed unnecessary semicolon"
* tag 'gfs2-for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
gfs2: Don't write log headers after file system withdraw
gfs2: Remove duplicate call from gfs2_create_inode
gfs2: clean up iopen glock mess in gfs2_create_inode
gfs2: Close timing window with GLF_INVALIDATE_IN_PROGRESS
gfs2: Abort gfs2_freeze if io error is seen
gfs2: Don't loop forever in gfs2_freeze if withdrawn
gfs2: fix infinite loop in gfs2_ail1_flush on io error
gfs2: Introduce function gfs2_withdrawn
gfs2: fix glock reference problem in gfs2_trans_remove_revoke
gfs2: make gfs2_log_shutdown static
gfs2: Remove active journal side effect from gfs2_write_log_header
gfs2: Fix end-of-file handling in gfs2_page_mkwrite
gfs2: Multi-block allocations in gfs2_page_mkwrite
gfs2: Improve mmap write vs. punch_hole consistency
gfs2: make gfs2_fs_parameters static
gfs2: Some whitespace cleanups
gfs2: removed unnecessary semicolon
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git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground
Pull removal of most of fs/compat_ioctl.c from Arnd Bergmann:
"As part of the cleanup of some remaining y2038 issues, I came to
fs/compat_ioctl.c, which still has a couple of commands that need
support for time64_t.
In completely unrelated work, I spent time on cleaning up parts of
this file in the past, moving things out into drivers instead.
After Al Viro reviewed an earlier version of this series and did a lot
more of that cleanup, I decided to try to completely eliminate the
rest of it and move it all into drivers.
This series incorporates some of Al's work and many patches of my own,
but in the end stops short of actually removing the last part, which
is the scsi ioctl handlers. I have patches for those as well, but they
need more testing or possibly a rewrite"
* tag 'compat-ioctl-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (42 commits)
scsi: sd: enable compat ioctls for sed-opal
pktcdvd: add compat_ioctl handler
compat_ioctl: move SG_GET_REQUEST_TABLE handling
compat_ioctl: ppp: move simple commands into ppp_generic.c
compat_ioctl: handle PPPIOCGIDLE for 64-bit time_t
compat_ioctl: move PPPIOCSCOMPRESS to ppp_generic
compat_ioctl: unify copy-in of ppp filters
tty: handle compat PPP ioctls
compat_ioctl: move SIOCOUTQ out of compat_ioctl.c
compat_ioctl: handle SIOCOUTQNSD
af_unix: add compat_ioctl support
compat_ioctl: reimplement SG_IO handling
compat_ioctl: move WDIOC handling into wdt drivers
fs: compat_ioctl: move FITRIM emulation into file systems
gfs2: add compat_ioctl support
compat_ioctl: remove unused convert_in_user macro
compat_ioctl: remove last RAID handling code
compat_ioctl: remove /dev/raw ioctl translation
compat_ioctl: remove PCI ioctl translation
compat_ioctl: remove joystick ioctl translation
...
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