dump_user_range() is used to copy the user page to a coredump file, but if
a hardware memory error occurred during copy, which called from
__kernel_write_iter() in dump_user_range(), it crashes,
CPU: 112 PID: 7014 Comm: mca-recover Not tainted 6.3.0-rc2 #425
pc : __memcpy+0x110/0x260
lr : _copy_from_iter+0x3bc/0x4c8
...
Call trace:
__memcpy+0x110/0x260
copy_page_from_iter+0xcc/0x130
pipe_write+0x164/0x6d8
__kernel_write_iter+0x9c/0x210
dump_user_range+0xc8/0x1d8
elf_core_dump+0x308/0x368
do_coredump+0x2e8/0xa40
get_signal+0x59c/0x788
do_signal+0x118/0x1f8
do_notify_resume+0xf0/0x280
el0_da+0x130/0x138
el0t_64_sync_handler+0x68/0xc0
el0t_64_sync+0x188/0x190
Generally, the '->write_iter' of file ops will use copy_page_from_iter()
and copy_page_from_iter_atomic(), change memcpy() to copy_mc_to_kernel()
in both of them to handle #MC during source read, which stop coredump
processing and kill the task instead of kernel panic, but the source
address may not always a user address, so introduce a new copy_mc flag in
struct iov_iter{} to indicate that the iter could do a safe memory copy,
also introduce the helpers to set/cleck the flag, for now, it's only used
in coredump's dump_user_range(), but it could expand to any other
scenarios to fix the similar issue.
Link: https://lkml.kernel.org/r/20230417045323.11054-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Tong Tiangen <tongtiangen@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pull MM updates from Andrew Morton:
- Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
switching from a user process to a kernel thread.
- More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
Raghav.
- zsmalloc performance improvements from Sergey Senozhatsky.
- Yue Zhao has found and fixed some data race issues around the
alteration of memcg userspace tunables.
- VFS rationalizations from Christoph Hellwig:
- removal of most of the callers of write_one_page()
- make __filemap_get_folio()'s return value more useful
- Luis Chamberlain has changed tmpfs so it no longer requires swap
backing. Use `mount -o noswap'.
- Qi Zheng has made the slab shrinkers operate locklessly, providing
some scalability benefits.
- Keith Busch has improved dmapool's performance, making part of its
operations O(1) rather than O(n).
- Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
permitting userspace to wr-protect anon memory unpopulated ptes.
- Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
rather than exclusive, and has fixed a bunch of errors which were
caused by its unintuitive meaning.
- Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
which causes minor faults to install a write-protected pte.
- Vlastimil Babka has done some maintenance work on vma_merge():
cleanups to the kernel code and improvements to our userspace test
harness.
- Cleanups to do_fault_around() by Lorenzo Stoakes.
- Mike Rapoport has moved a lot of initialization code out of various
mm/ files and into mm/mm_init.c.
- Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
DRM, but DRM doesn't use it any more.
- Lorenzo has also coverted read_kcore() and vread() to use iterators
and has thereby removed the use of bounce buffers in some cases.
- Lorenzo has also contributed further cleanups of vma_merge().
- Chaitanya Prakash provides some fixes to the mmap selftesting code.
- Matthew Wilcox changes xfs and afs so they no longer take sleeping
locks in ->map_page(), a step towards RCUification of pagefaults.
- Suren Baghdasaryan has improved mmap_lock scalability by switching to
per-VMA locking.
- Frederic Weisbecker has reworked the percpu cache draining so that it
no longer causes latency glitches on cpu isolated workloads.
- Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
logic.
- Liu Shixin has changed zswap's initialization so we no longer waste a
chunk of memory if zswap is not being used.
- Yosry Ahmed has improved the performance of memcg statistics
flushing.
- David Stevens has fixed several issues involving khugepaged,
userfaultfd and shmem.
- Christoph Hellwig has provided some cleanup work to zram's IO-related
code paths.
- David Hildenbrand has fixed up some issues in the selftest code's
testing of our pte state changing.
- Pankaj Raghav has made page_endio() unneeded and has removed it.
- Peter Xu contributed some rationalizations of the userfaultfd
selftests.
- Yosry Ahmed has fixed an issue around memcg's page recalim
accounting.
- Chaitanya Prakash has fixed some arm-related issues in the
selftests/mm code.
- Longlong Xia has improved the way in which KSM handles hwpoisoned
pages.
- Peter Xu fixes a few issues with uffd-wp at fork() time.
- Stefan Roesch has changed KSM so that it may now be used on a
per-process and per-cgroup basis.
* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
shmem: restrict noswap option to initial user namespace
mm/khugepaged: fix conflicting mods to collapse_file()
sparse: remove unnecessary 0 values from rc
mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
maple_tree: fix allocation in mas_sparse_area()
mm: do not increment pgfault stats when page fault handler retries
zsmalloc: allow only one active pool compaction context
selftests/mm: add new selftests for KSM
mm: add new KSM process and sysfs knobs
mm: add new api to enable ksm per process
mm: shrinkers: fix debugfs file permissions
mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
migrate_pages_batch: fix statistics for longterm pin retry
userfaultfd: use helper function range_in_vma()
lib/show_mem.c: use for_each_populated_zone() simplify code
mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
fs/buffer: convert create_page_buffers to folio_create_buffers
fs/buffer: add folio_create_empty_buffers helper
...
Provide a means to copy a page to user space from an iterator, aborting if
a page fault would occur. This supports compound pages, but may be passed
a tail page with an offset extending further into the compound page, so we
cannot pass a folio.
This allows for this function to be called from atomic context and _try_
to user pages if they are faulted in, aborting if not.
The function does not use _copy_to_iter() in order to not specify
might_fault(), this is similar to copy_page_from_iter_atomic().
This is being added in order that an iteratable form of vread() can be
implemented while holding spinlocks.
Link: https://lkml.kernel.org/r/19734729defb0f498a76bdec1bef3ac48a3af3e8.1679511146.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add an internal struct iovec that we can return as a pointer, with the
fields of the iovec overlapping with the ITER_UBUF ubuf and length
fields.
Then we can have iter_iov() check for the appropriate type, and return
&iter->__ubuf_iovec for ITER_UBUF and iter->__iov for ITER_IOVEC and
things will magically work out for a single segment request regardless
of either type.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
To avoid needing to check if a given user backed iov_iter is of type
ITER_IOVEC or ITER_UBUF, set the number of segments for the ITER_UBUF
case to 1 as we're carrying a single segment.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
These just return the address and length of the current iovec segment
in the iterator. Convert existing iov_iter_iovec() users to use them
instead of getting a copy of the current vec.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This returns a pointer to the current iovec entry in the iterator. Only
useful with ITER_IOVEC right now, but it prepares us to treat ITER_UBUF
and ITER_IOVEC identically for the first segment.
Rename struct iov_iter->iov to iov_iter->__iov to find any potentially
troublesome spots, and also to prevent anyone from adding new code that
accesses iter->iov directly.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull cifs client updates from Steve French:
"The largest subset of this is from David Howells et al: making the
cifs/smb3 driver pass iov_iters down to the lowest layers, directly to
the network transport rather than passing lists of pages around,
helping multiple areas:
- Pin user pages, thereby fixing the race between concurrent DIO read
and fork, where the pages containing the DIO read buffer may end up
belonging to the child process and not the parent - with the result
that the parent might not see the retrieved data.
- cifs shouldn't take refs on pages extracted from non-user-backed
iterators (eg. KVEC). With these changes, cifs will apply the
appropriate cleanup.
- Making it easier to transition to using folios in cifs rather than
pages by dealing with them through BVEC and XARRAY iterators.
- Allowing cifs to use the new splice function
The remainder are:
- fixes for stable, including various fixes for uninitialized memory,
wrong length field causing mount issue to very old servers,
important directory lease fixes and reconnect fixes
- cleanups (unused code removal, change one element array usage, and
a change form strtobool to kstrtobool, and Kconfig cleanups)
- SMBDIRECT (RDMA) fixes including iov_iter integration and UAF fixes
- reconnect fixes
- multichannel fixes, including improving channel allocation (to
least used channel)
- remove the last use of lock_page_killable by moving to
folio_lock_killable"
* tag '6.3-rc-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6: (46 commits)
update internal module version number for cifs.ko
cifs: update ip_addr for ses only for primary chan setup
cifs: use tcon allocation functions even for dummy tcon
cifs: use the least loaded channel for sending requests
cifs: DIO to/from KVEC-type iterators should now work
cifs: Remove unused code
cifs: Build the RDMA SGE list directly from an iterator
cifs: Change the I/O paths to use an iterator rather than a page list
cifs: Add a function to read into an iter from a socket
cifs: Add some helper functions
cifs: Add a function to Hash the contents of an iterator
cifs: Add a function to build an RDMA SGE list from an iterator
netfs: Add a function to extract an iterator into a scatterlist
netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator
cifs: Implement splice_read to pass down ITER_BVEC not ITER_PIPE
splice: Export filemap/direct_splice_read()
iov_iter: Add a function to extract a page list from an iterator
iov_iter: Define flags to qualify page extraction.
splice: Add a func to do a splice from an O_DIRECT file without ITER_PIPE
splice: Add a func to do a splice from a buffered file without ITER_PIPE
...
Add a function, iov_iter_extract_pages(), to extract a list of pages from
an iterator. The pages may be returned with a pin added or nothing,
depending on the type of iterator.
Add a second function, iov_iter_extract_will_pin(), to determine how the
cleanup should be done.
There are two cases:
(1) ITER_IOVEC or ITER_UBUF iterator.
Extracted pages will have pins (FOLL_PIN) obtained on them so that a
concurrent fork() will forcibly copy the page so that DMA is done
to/from the parent's buffer and is unavailable to/unaffected by the
child process.
iov_iter_extract_will_pin() will return true for this case. The
caller should use something like unpin_user_page() to dispose of the
page.
(2) Any other sort of iterator.
No refs or pins are obtained on the page, the assumption is made that
the caller will manage page retention.
iov_iter_extract_will_pin() will return false. The pages don't need
additional disposal.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: John Hubbard <jhubbard@nvidia.com>
cc: David Hildenbrand <david@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Like import_single_range(), but for ITER_UBUF.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Pull block updates from Jens Axboe:
- NVMe pull requests via Christoph:
- Support some passthrough commands without CAP_SYS_ADMIN (Kanchan
Joshi)
- Refactor PCIe probing and reset (Christoph Hellwig)
- Various fabrics authentication fixes and improvements (Sagi
Grimberg)
- Avoid fallback to sequential scan due to transient issues (Uday
Shankar)
- Implement support for the DEAC bit in Write Zeroes (Christoph
Hellwig)
- Allow overriding the IEEE OUI and firmware revision in configfs
for nvmet (Aleksandr Miloserdov)
- Force reconnect when number of queue changes in nvmet (Daniel
Wagner)
- Minor fixes and improvements (Uros Bizjak, Joel Granados, Sagi
Grimberg, Christoph Hellwig, Christophe JAILLET)
- Fix and cleanup nvme-fc req allocation (Chaitanya Kulkarni)
- Use the common tagset helpers in nvme-pci driver (Christoph
Hellwig)
- Cleanup the nvme-pci removal path (Christoph Hellwig)
- Use kstrtobool() instead of strtobool (Christophe JAILLET)
- Allow unprivileged passthrough of Identify Controller (Joel
Granados)
- Support io stats on the mpath device (Sagi Grimberg)
- Minor nvmet cleanup (Sagi Grimberg)
- MD pull requests via Song:
- Code cleanups (Christoph)
- Various fixes
- Floppy pull request from Denis:
- Fix a memory leak in the init error path (Yuan)
- Series fixing some batch wakeup issues with sbitmap (Gabriel)
- Removal of the pktcdvd driver that was deprecated more than 5 years
ago, and subsequent removal of the devnode callback in struct
block_device_operations as no users are now left (Greg)
- Fix for partition read on an exclusively opened bdev (Jan)
- Series of elevator API cleanups (Jinlong, Christoph)
- Series of fixes and cleanups for blk-iocost (Kemeng)
- Series of fixes and cleanups for blk-throttle (Kemeng)
- Series adding concurrent support for sync queues in BFQ (Yu)
- Series bringing drbd a bit closer to the out-of-tree maintained
version (Christian, Joel, Lars, Philipp)
- Misc drbd fixes (Wang)
- blk-wbt fixes and tweaks for enable/disable (Yu)
- Fixes for mq-deadline for zoned devices (Damien)
- Add support for read-only and offline zones for null_blk
(Shin'ichiro)
- Series fixing the delayed holder tracking, as used by DM (Yu,
Christoph)
- Series enabling bio alloc caching for IRQ based IO (Pavel)
- Series enabling userspace peer-to-peer DMA (Logan)
- BFQ waker fixes (Khazhismel)
- Series fixing elevator refcount issues (Christoph, Jinlong)
- Series cleaning up references around queue destruction (Christoph)
- Series doing quiesce by tagset, enabling cleanups in drivers
(Christoph, Chao)
- Series untangling the queue kobject and queue references (Christoph)
- Misc fixes and cleanups (Bart, David, Dawei, Jinlong, Kemeng, Ye,
Yang, Waiman, Shin'ichiro, Randy, Pankaj, Christoph)
* tag 'for-6.2/block-2022-12-08' of git://git.kernel.dk/linux: (247 commits)
blktrace: Fix output non-blktrace event when blk_classic option enabled
block: sed-opal: Don't include <linux/kernel.h>
sed-opal: allow using IOC_OPAL_SAVE for locking too
blk-cgroup: Fix typo in comment
block: remove bio_set_op_attrs
nvmet: don't open-code NVME_NS_ATTR_RO enumeration
nvme-pci: use the tagset alloc/free helpers
nvme: add the Apple shared tag workaround to nvme_alloc_io_tag_set
nvme: only set reserved_tags in nvme_alloc_io_tag_set for fabrics controllers
nvme: consolidate setting the tagset flags
nvme: pass nr_maps explicitly to nvme_alloc_io_tag_set
block: bio_copy_data_iter
nvme-pci: split out a nvme_pci_ctrl_is_dead helper
nvme-pci: return early on ctrl state mismatch in nvme_reset_work
nvme-pci: rename nvme_disable_io_queues
nvme-pci: cleanup nvme_suspend_queue
nvme-pci: remove nvme_pci_disable
nvme-pci: remove nvme_disable_admin_queue
nvme: merge nvme_shutdown_ctrl into nvme_disable_ctrl
nvme: use nvme_wait_ready in nvme_shutdown_ctrl
...
READ/WRITE proved to be actively confusing - the meanings are
"data destination, as used with read(2)" and "data source, as
used with write(2)", but people keep interpreting those as
"we read data from it" and "we write data to it", i.e. exactly
the wrong way.
Call them ITER_DEST and ITER_SOURCE - at least that is harder
to misinterpret...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This was intended to be "maxpages" instead of INT_MAX. There is only
one caller and it passes INT_MAX so this does not affect runtime.
Fixes: b93235e689 ("tls: cap the output scatter list to something reasonable")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Most of the users immediately follow successful iov_iter_get_pages()
with advancing by the amount it had returned.
Provide inline wrappers doing that, convert trivial open-coded
uses of those.
BTW, iov_iter_get_pages() never returns more than it had been asked
to; such checks in cifs ought to be removed someday...
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We often need to find whether the last buffer is anon or not, and
currently it's rather clumsy:
check if ->iov_offset is non-zero (i.e. that pipe is not empty)
if so, get the corresponding pipe_buffer and check its ->ops
if it's &default_pipe_buf_ops, we have an anon buffer.
Let's replace the use of ->iov_offset (which is nowhere near similar to
its role for other flavours) with signed field (->last_offset), with
the following rules:
empty, no buffers occupied: 0
anon, with bytes up to N-1 filled: N
zero-copy, with bytes up to N-1 filled: -N
That way abs(i->last_offset) is equal to what used to be in i->iov_offset
and empty vs. anon vs. zero-copy can be distinguished by the sign of
i->last_offset.
Checks for "should we extend the last buffer or should we start
a new one?" become easier to follow that way.
Note that most of the operations can only be done in a sane
state - i.e. when the pipe has nothing past the current position of
iterator. About the only thing that could be done outside of that
state is iov_iter_advance(), which transitions to the sane state by
truncating the pipe. There are only two cases where we leave the
sane state:
1) iov_iter_get_pages()/iov_iter_get_pages_alloc(). Will be
dealt with later, when we make get_pages advancing - the callers are
actually happier that way.
2) iov_iter copied, then something is put into the copy. Since
they share the underlying pipe, the original gets behind. When we
decide that we are done with the copy (original is not usable until then)
we advance the original. direct_io used to be done that way; nowadays
it operates on the original and we do iov_iter_revert() to discard
the excessive data. At the moment there's nothing in the kernel that
could do that to ITER_PIPE iterators, so this reason for insane state
is theoretical right now.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Equivalent of single-segment iovec. Initialized by iov_iter_ubuf(),
checked for by iter_is_ubuf(), otherwise behaves like ITER_IOVEC
ones.
We are going to expose the things like ->write_iter() et.al. to those
in subsequent commits.
New predicate (user_backed_iter()) that is true for ITER_IOVEC and
ITER_UBUF; places like direct-IO handling should use that for
checking that pages we modify after getting them from iov_iter_get_pages()
would need to be dirtied.
DO NOT assume that replacing iter_is_iovec() with user_backed_iter()
will solve all problems - there's code that uses iter_is_iovec() to
decide how to poke around in iov_iter guts and for that the predicate
replacement obviously won't suffice.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull vfs iov_iter updates from Al Viro:
"Part 1 - isolated cleanups and optimizations.
One of the goals is to reduce the overhead of using ->read_iter() and
->write_iter() instead of ->read()/->write().
new_sync_{read,write}() has a surprising amount of overhead, in
particular inside iocb_flags(). That's the explanation for the
beginning of the series is in this pile; it's not directly
iov_iter-related, but it's a part of the same work..."
* tag 'pull-work.iov_iter-base' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
first_iovec_segment(): just return address
iov_iter: massage calling conventions for first_{iovec,bvec}_segment()
iov_iter: first_{iovec,bvec}_segment() - simplify a bit
iov_iter: lift dealing with maxpages out of first_{iovec,bvec}_segment()
iov_iter_get_pages{,_alloc}(): cap the maxsize with MAX_RW_COUNT
iov_iter_bvec_advance(): don't bother with bvec_iter
copy_page_{to,from}_iter(): switch iovec variants to generic
keep iocb_flags() result cached in struct file
iocb: delay evaluation of IS_SYNC(...) until we want to check IOCB_DSYNC
struct file: use anonymous union member for rcuhead and llist
btrfs: use IOMAP_DIO_NOSYNC
teach iomap_dio_rw() to suppress dsync
No need of likely/unlikely on calls of check_copy_size()
The existing iov_iter_alignment() function returns the logical OR of
address and length. For cases where address and length need to be
considered separately, introduce a helper function that a caller can
specificy length and address masks that indicate if the iov is
unaligned.
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220610195830.3574005-9-kbusch@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
it's inline and unlikely() inside of it (including the implicit one
in WARN_ON_ONCE()) suffice to convince the compiler that getting
false from check_copy_size() is unlikely.
Spotted-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
TLS recvmsg() passes user pages as destination for decrypt.
The decrypt operation is repeated record by record, each
record being 16kB, max. TLS allocates an sg_table and uses
iov_iter_get_pages() to populate it with enough pages to
fit the decrypted record.
Even though we decrypt a single message at a time we size
the sg_table based on the entire length of the iovec.
This leads to unnecessarily large allocations, risking
triggering OOM conditions.
Use iov_iter_truncate() / iov_iter_reexpand() to construct
a "capped" version of iov_iter_npages(). Alternatively we
could parametrize iov_iter_npages() to take the size as
arg instead of using i->count, or do something else..
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull dax and libnvdimm updates from Dan Williams:
"The bulk of this is a rework of the dax_operations API after
discovering the obstacles it posed to the work-in-progress DAX+reflink
support for XFS and other copy-on-write filesystem mechanics.
Primarily the need to plumb a block_device through the API to handle
partition offsets was a sticking point and Christoph untangled that
dependency in addition to other cleanups to make landing the
DAX+reflink support easier.
The DAX_PMEM_COMPAT option has been around for 4 years and not only
are distributions shipping userspace that understand the current
configuration API, but some are not even bothering to turn this option
on anymore, so it seems a good time to remove it per the deprecation
schedule. Recall that this was added after the device-dax subsystem
moved from /sys/class/dax to /sys/bus/dax for its sysfs organization.
All recent functionality depends on /sys/bus/dax.
Some other miscellaneous cleanups and reflink prep patches are
included as well.
Summary:
- Simplify the dax_operations API:
- Eliminate bdev_dax_pgoff() in favor of the filesystem
maintaining and applying a partition offset to all its DAX iomap
operations.
- Remove wrappers and device-mapper stacked callbacks for
->copy_from_iter() and ->copy_to_iter() in favor of moving
block_device relative offset responsibility to the
dax_direct_access() caller.
- Remove the need for an @bdev in filesystem-DAX infrastructure
- Remove unused uio helpers copy_from_iter_flushcache() and
copy_mc_to_iter() as only the non-check_copy_size() versions are
used for DAX.
- Prepare XFS for the pending (next merge window) DAX+reflink support
- Remove deprecated DEV_DAX_PMEM_COMPAT support
- Cleanup a straggling misuse of the GUID api"
* tag 'libnvdimm-for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (38 commits)
iomap: Fix error handling in iomap_zero_iter()
ACPI: NFIT: Import GUID before use
dax: remove the copy_from_iter and copy_to_iter methods
dax: remove the DAXDEV_F_SYNC flag
dax: simplify dax_synchronous and set_dax_synchronous
uio: remove copy_from_iter_flushcache() and copy_mc_to_iter()
iomap: turn the byte variable in iomap_zero_iter into a ssize_t
memremap: remove support for external pgmap refcounts
fsdax: don't require CONFIG_BLOCK
iomap: build the block based code conditionally
dax: fix up some of the block device related ifdefs
fsdax: shift partition offset handling into the file systems
dax: return the partition offset from fs_dax_get_by_bdev
iomap: add a IOMAP_DAX flag
xfs: pass the mapping flags to xfs_bmbt_to_iomap
xfs: use xfs_direct_write_iomap_ops for DAX zeroing
xfs: move dax device handling into xfs_{alloc,free}_buftarg
ext4: cleanup the dax handling in ext4_fill_super
ext2: cleanup the dax handling in ext2_fill_super
fsdax: decouple zeroing from the iomap buffered I/O code
...
This wrapper around copy_page_to_iter() works because copy_page_to_iter()
handles compound pages correctly.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Introduce a new nofault flag to indicate to iov_iter_get_pages not to
fault in user pages.
This is implemented by passing the FOLL_NOFAULT flag to get_user_pages,
which causes get_user_pages to fail when it would otherwise fault in a
page. We'll use the ->nofault flag to prevent iomap_dio_rw from faulting
in pages when page faults are not allowed.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Introduce a new fault_in_iov_iter_writeable helper for safely faulting
in an iterator for writing. Uses get_user_pages() to fault in the pages
without actually writing to them, which would be destructive.
We'll use fault_in_iov_iter_writeable in gfs2 once we've determined that
the iterator passed to .read_iter isn't in memory.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Turn iov_iter_fault_in_readable into a function that returns the number
of bytes not faulted in, similar to copy_to_user, instead of returning a
non-zero value when any of the requested pages couldn't be faulted in.
This supports the existing users that require all pages to be faulted in
as well as new users that are happy if any pages can be faulted in.
Rename iov_iter_fault_in_readable to fault_in_iov_iter_readable to make
sure this change doesn't silently break things.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This reverts commit 2112ff5ce0.
We no longer need to track the truncation count, the one user that did
need it has been converted to using iov_iter_restore() instead.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In an ideal world, when someone is passed an iov_iter and returns X bytes,
then X bytes would have been consumed/advanced from the iov_iter. But we
have use cases that always consume the entire iterator, a few examples
of that are iomap and bdev O_DIRECT. This means we cannot rely on the
state of the iov_iter once we've called ->read_iter() or ->write_iter().
This would be easier if we didn't always have to deal with truncate of
the iov_iter, as rewinding would be trivial without that. We recently
added a commit to track the truncate state, but that grew the iov_iter
by 8 bytes and wasn't the best solution.
Implement a helper to save enough of the iov_iter state to sanely restore
it after we've called the read/write iterator helpers. This currently
only works for IOVEC/BVEC/KVEC as that's all we need, support for other
iterator types are left as an exercise for the reader.
Link: https://lore.kernel.org/linux-fsdevel/CAHk-=wiacKV4Gh-MYjteU0LwNBSGpWrK-Ov25HdqB1ewinrFPg@mail.gmail.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remember how many bytes were truncated and reverted back. Because
not reexpanded iterators don't always work well with reverting, we may
need to know that to reexpand ourselves when needed.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Replacement is called copy_page_from_iter_atomic(); unlike the old primitive the
callers do *not* need to do iov_iter_advance() after it. In case when they end
up consuming less than they'd been given they need to do iov_iter_revert() on
everything they had not consumed. That, however, needs to be done only on slow
paths.
All in-tree callers converted. And that kills the last user of iterate_all_kinds()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1) constify iov_iter argument; we are not advancing it in this primitive.
2) cap the amount requested by the amount of data in iov_iter. All
existing callers should've been safe, but the check is really cheap and
doing it here makes for easier analysis, as well as more consistent
semantics among the primitives.
3) don't bother with iterate_iovec(). Explicit loop is not any harder
to follow, and we get rid of standalone iterate_iovec() users - it's
only used by iterate_and_advance() and (soon to be gone) iterate_all_kinds().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Instead of having them mixed in iter->type, use separate ->iter_type
and ->data_source (u8 and bool resp.) And don't bother with (pseudo-)
bitmap for the former - microoptimizations from being able to check
if the flavour is one of two values are not worth the confusion for
optimizer. It can't prove that we never get e.g. ITER_IOVEC | ITER_PIPE,
so we end up with extra headache.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Use corresponding plain variants, revert on short copy. That's the way it
should've been done from the very beginning, except that we didn't have
iov_iter_revert() back then...
[fixed another braino caught by Qian Cai <quic_qiancai@quicinc.com>]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Remove iov_iter_for_each_range() as it's no longer used with the removal of
lustre.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Fix four things[1] in the patch that adds ITER_XARRAY[2]:
(1) Remove the address_space struct predeclaration. This is a holdover
from when it was ITER_MAPPING.
(2) Fix _copy_mc_to_iter() so that the xarray segment updates count and
iov_offset in the iterator before returning.
(3) Fix iov_iter_alignment() to not loop in the xarray case. Because the
middle pages are all whole pages, only the end pages need be
considered - and this can be reduced to just looking at the start
position in the xarray and the iteration size.
(4) Fix iov_iter_advance() to limit the size of the advance to no more
than the remaining iteration size.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Jeff Layton <jlayton@redhat.com>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Link: https://lore.kernel.org/r/YIVrJT8GwLI0Wlgx@zeniv-ca.linux.org.uk [1]
Link: https://lore.kernel.org/r/161918448151.3145707.11541538916600921083.stgit@warthog.procyon.org.uk [2]
Pull compat iovec cleanups from Al Viro:
"Christoph's series around import_iovec() and compat variant thereof"
* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
security/keys: remove compat_keyctl_instantiate_key_iov
mm: remove compat_process_vm_{readv,writev}
fs: remove compat_sys_vmsplice
fs: remove the compat readv/writev syscalls
fs: remove various compat readv/writev helpers
iov_iter: transparently handle compat iovecs in import_iovec
iov_iter: refactor rw_copy_check_uvector and import_iovec
iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c
compat.h: fix a spelling error in <linux/compat.h>
In reaction to a proposal to introduce a memcpy_mcsafe_fast()
implementation Linus points out that memcpy_mcsafe() is poorly named
relative to communicating the scope of the interface. Specifically what
addresses are valid to pass as source, destination, and what faults /
exceptions are handled.
Of particular concern is that even though x86 might be able to handle
the semantics of copy_mc_to_user() with its common copy_user_generic()
implementation other archs likely need / want an explicit path for this
case:
On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
> On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote:
> >
> > However now I see that copy_user_generic() works for the wrong reason.
> > It works because the exception on the source address due to poison
> > looks no different than a write fault on the user address to the
> > caller, it's still just a short copy. So it makes copy_to_user() work
> > for the wrong reason relative to the name.
>
> Right.
>
> And it won't work that way on other architectures. On x86, we have a
> generic function that can take faults on either side, and we use it
> for both cases (and for the "in_user" case too), but that's an
> artifact of the architecture oddity.
>
> In fact, it's probably wrong even on x86 - because it can hide bugs -
> but writing those things is painful enough that everybody prefers
> having just one function.
Replace a single top-level memcpy_mcsafe() with either
copy_mc_to_user(), or copy_mc_to_kernel().
Introduce an x86 copy_mc_fragile() name as the rename for the
low-level x86 implementation formerly named memcpy_mcsafe(). It is used
as the slow / careful backend that is supplanted by a fast
copy_mc_generic() in a follow-on patch.
One side-effect of this reorganization is that separating copy_mc_64.S
to its own file means that perf no longer needs to track dependencies
for its memcpy_64.S benchmarks.
[ bp: Massage a bit. ]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: <stable@vger.kernel.org>
Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com
Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com
Use in compat_syscall to import either native or the compat iovecs, and
remove the now superflous compat_import_iovec.
This removes the need for special compat logic in most callers, and
the remaining ones can still be simplified by using __import_iovec
with a bool compat parameter.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Split rw_copy_check_uvector into two new helpers with more sensible
calling conventions:
- iovec_from_user copies a iovec from userspace either into the provided
stack buffer if it fits, or allocates a new buffer for it. Returns
the actually used iovec. It also verifies that iov_len does fit a
signed type, and handles compat iovecs if the compat flag is set.
- __import_iovec consolidates the native and compat versions of
import_iovec. It calls iovec_from_user, then validates each iovec
actually points to user addresses, and ensures the total length
doesn't overflow.
This has two major implications:
- the access_process_vm case loses the total lenght checking, which
wasn't required anyway, given that each call receives two iovecs
for the local and remote side of the operation, and it verifies
the total length on the local side already.
- instead of a single loop there now are two loops over the iovecs.
Given that the iovecs are cache hot this doesn't make a major
difference
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The header file linux/uio.h includes crypto/hash.h which pulls in
most of the Crypto API. Since linux/uio.h is used throughout the
kernel this means that every tiny bit of change to the Crypto API
causes the entire kernel to get rebuilt.
This patch fixes this by moving it into lib/iov_iter.c instead
where it is actually used.
This patch also fixes the ifdef to use CRYPTO_HASH instead of just
CRYPTO which does not guarantee the existence of ahash.
Unfortunately a number of drivers were relying on linux/uio.h to
provide access to linux/slab.h. This patch adds inclusions of
linux/slab.h as detected by build failures.
Also skbuff.h was relying on this to provide a declaration for
ahash_request. This patch adds a forward declaration instead.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Convert pipes to use head and tail pointers for the buffer ring rather than
pointer and length as the latter requires two atomic ops to update (or a
combined op) whereas the former only requires one.
(1) The head pointer is the point at which production occurs and points to
the slot in which the next buffer will be placed. This is equivalent
to pipe->curbuf + pipe->nrbufs.
The head pointer belongs to the write-side.
(2) The tail pointer is the point at which consumption occurs. It points
to the next slot to be consumed. This is equivalent to pipe->curbuf.
The tail pointer belongs to the read-side.
(3) head and tail are allowed to run to UINT_MAX and wrap naturally. They
are only masked off when the array is being accessed, e.g.:
pipe->bufs[head & mask]
This means that it is not necessary to have a dead slot in the ring as
head == tail isn't ambiguous.
(4) The ring is empty if "head == tail".
A helper, pipe_empty(), is provided for this.
(5) The occupancy of the ring is "head - tail".
A helper, pipe_occupancy(), is provided for this.
(6) The number of free slots in the ring is "pipe->ring_size - occupancy".
A helper, pipe_space_for_user() is provided to indicate how many slots
userspace may use.
(7) The ring is full if "head - tail >= pipe->ring_size".
A helper, pipe_full(), is provided for this.
Signed-off-by: David Howells <dhowells@redhat.com>
Pull io_uring updates from Jens Axboe:
"This contains:
- Support for recvmsg/sendmsg as first class opcodes.
I don't envision going much further down this path, as there are
plans in progress to support potentially any system call in an
async fashion through io_uring. But I think it does make sense to
have certain core ops available directly, especially those that can
support a "try this non-blocking" flag/mode. (me)
- Handle generic short reads automatically.
This can happen fairly easily if parts of the buffered read is
cached. Since the application needs to issue another request for
the remainder, just do this internally and save kernel/user
roundtrip while providing a nicer more robust API. (me)
- Support for linked SQEs.
This allows SQEs to depend on each other, enabling an application
to eg queue a read-from-this-file,write-to-that-file pair. (me)
- Fix race in stopping SQ thread (Jackie)"
* tag 'for-5.3/io_uring-20190711' of git://git.kernel.dk/linux-block:
io_uring: fix io_sq_thread_stop running in front of io_sq_thread
io_uring: add support for recvmsg()
io_uring: add support for sendmsg()
io_uring: add support for sqe links
io_uring: punt short reads to async context
uio: make import_iovec()/compat_import_iovec() return bytes on success
If we pass pages through an iov_iter we always already have a reference
in the caller. Thus remove the ITER_BVEC_FLAG_NO_REF and don't take
reference to pages by default for bvec backed iov_iters.
Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
