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.
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Merge tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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
...
* The data=journal writepath has been significantly cleaned up and
simplified, and reduces a large number of data=journal special cases
by Jan Kara.
* Ojaswin Muhoo has replaced linked list used to track extents that
have been used for inode preallocation with a red-black tree in the
multi-block allocator. This improves performance for workloads
which do a large number of random allocating writes.
* Thanks to Kemeng Shi for a lot of cleanup and bug fixes in the
multi-block allocator.
* Matthew wilcox has converted the code paths for reading and writing
ext4 pages to use folios.
* Jason Yan has continued to factor out ext4_fill_super() into smaller
functions for improve ease of maintenance and comprehension.
* Josh Triplett has created an uapi header for ext4 userspace API's.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"There are a number of major cleanups in ext4 this cycle:
- The data=journal writepath has been significantly cleaned up and
simplified, and reduces a large number of data=journal special
cases by Jan Kara.
- Ojaswin Muhoo has replaced linked list used to track extents that
have been used for inode preallocation with a red-black tree in the
multi-block allocator. This improves performance for workloads
which do a large number of random allocating writes.
- Thanks to Kemeng Shi for a lot of cleanup and bug fixes in the
multi-block allocator.
- Matthew wilcox has converted the code paths for reading and writing
ext4 pages to use folios.
- Jason Yan has continued to factor out ext4_fill_super() into
smaller functions for improve ease of maintenance and
comprehension.
- Josh Triplett has created an uapi header for ext4 userspace API's"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (105 commits)
ext4: Add a uapi header for ext4 userspace APIs
ext4: remove useless conditional branch code
ext4: remove unneeded check of nr_to_submit
ext4: move dax and encrypt checking into ext4_check_feature_compatibility()
ext4: factor out ext4_block_group_meta_init()
ext4: move s_reserved_gdt_blocks and addressable checking into ext4_check_geometry()
ext4: rename two functions with 'check'
ext4: factor out ext4_flex_groups_free()
ext4: use ext4_group_desc_free() in ext4_put_super() to save some duplicated code
ext4: factor out ext4_percpu_param_init() and ext4_percpu_param_destroy()
ext4: factor out ext4_hash_info_init()
Revert "ext4: Fix warnings when freezing filesystem with journaled data"
ext4: Update comment in mpage_prepare_extent_to_map()
ext4: Simplify handling of journalled data in ext4_bmap()
ext4: Drop special handling of journalled data from ext4_quota_on()
ext4: Drop special handling of journalled data from ext4_evict_inode()
ext4: Fix special handling of journalled data from extent zeroing
ext4: Drop special handling of journalled data from extent shifting operations
ext4: Drop special handling of journalled data from ext4_sync_file()
ext4: Commit transaction before writing back pages in data=journal mode
...
Fix netfs_extract_iter_to_sg() for ITER_UBUF and ITER_IOVEC to set the
size of the page to the part of the page extracted, not the remaining
amount of data in the extracted page array at that point.
This doesn't yet affect anything as cifs, the only current user, only
passes in non-user-backed iterators.
Fixes: 0185846975 ("netfs: Add a function to extract an iterator into a scatterlist")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Cc: Steve French <sfrench@samba.org>
Cc: Shyam Prasad N <nspmangalore@gmail.com>
Cc: Rohith Surabattula <rohiths.msft@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This particular combination of flags is used by most filesystems
in their ->write_begin method, although it does find use in a
few other places. Before folios, it warranted its own function
(grab_cache_page_write_begin()), but I think that just having specialised
flags is enough. It certainly helps the few places that have been
converted from grab_cache_page_write_begin() to __filemap_get_folio().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-2-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Instead of returning NULL for all errors, distinguish between:
- no entry found and not asked to allocated (-ENOENT)
- failed to allocate memory (-ENOMEM)
- would block (-EAGAIN)
so that callers don't have to guess the error based on the passed in
flags.
Also pass through the error through the direct callers: filemap_get_folio,
filemap_lock_folio filemap_grab_folio and filemap_get_incore_folio.
[hch@lst.de: fix null-pointer deref]
Link: https://lkml.kernel.org/r/20230310070023.GA13563@lst.de
Link: https://lkml.kernel.org/r/20230310043137.GA1624890@u2004
Link: https://lkml.kernel.org/r/20230307143410.28031-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> [nilfs2]
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Fix the loop check in netfs_extract_user_to_sg() for extraction from
user-backed iterators to do the body if npages > 0, not if npages < 0
(which it can never be).
This isn't currently used by cifs, which only ever extracts data from BVEC,
KVEC and XARRAY iterators at this level, user-backed iterators having being
decanted into BVEC iterators at a higher level to accommodate the work
being done in a kernel thread.
Found by smatch:
fs/netfs/iterator.c:139 netfs_extract_user_to_sg() warn: unsigned 'npages' is never less than zero.
Fixes: 0185846975 ("netfs: Add a function to extract an iterator into a scatterlist")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202302261115.P3TQi1ZO-lkp@intel.com/
Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/Y/yYnAhoAYDBKixX@kili
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: linux-cachefs@redhat.com
Signed-off-by: Steve French <stfrench@microsoft.com>
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Merge tag '6.3-rc-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6
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
...
Provide a function for filling in a scatterlist from the list of pages
contained in an iterator.
If the iterator is UBUF- or IOBUF-type, the pages have a pin taken on them
(as FOLL_PIN).
If the iterator is BVEC-, KVEC- or XARRAY-type, no pin is taken on the
pages and it is left to the caller to manage their lifetime. It cannot be
assumed that a ref can be validly taken, particularly in the case of a KVEC
iterator.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: linux-cachefs@redhat.com
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Add a function to extract the pages from a user-space supplied iterator
(UBUF- or IOVEC-type) into a BVEC-type iterator, retaining the pages by
getting a pin on them (as FOLL_PIN) as we go.
This is useful in three situations:
(1) A userspace thread may have a sibling that unmaps or remaps the
process's VM during the operation, changing the assignment of the
pages and potentially causing an error. Retaining the pages keeps
some pages around, even if this occurs; futher, we find out at the
point of extraction if EFAULT is going to be incurred.
(2) Pages might get swapped out/discarded if not retained, so we want to
retain them to avoid the reload causing a deadlock due to a DIO
from/to an mmapped region on the same file.
(3) The iterator may get passed to sendmsg() by the filesystem. If a
fault occurs, we may get a short write to a TCP stream that's then
tricky to recover from.
We don't deal with other types of iterator here, leaving it to other
mechanisms to retain the pages (eg. PG_locked, PG_writeback and the pipe
lock).
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: linux-cachefs@redhat.com
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
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>
Fix the dodgy maths in netfs_rreq_unlock_folios(). start_page could be
inside the folio, in which case the calculation of pgpos will be come up
with a negative number (though for the moment rreq->start is rounded down
earlier and folios would have to get merged whilst locked)
Alter how this works to just frame the tracking in terms of absolute file
positions, rather than offsets from the start of the I/O request. This
simplifies the maths and makes it easier to follow.
Fix the issue by using folio_pos() and folio_size() to calculate the end
position of the page.
Fixes: 3d3c950467 ("netfs: Provide readahead and readpage netfs helpers")
Reported-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/Y2SJw7w1IsIik3nb@casper.infradead.org/
Link: https://lore.kernel.org/r/166757988611.950645.7626959069846893164.stgit@warthog.procyon.org.uk/ # v2
netfslib has a number of places in which it performs iteration of an xarray
whilst being under the RCU read lock. It *should* call xas_retry() as the
first thing inside of the loop and do "continue" if it returns true in case
the xarray walker passed out a special value indicating that the walk needs
to be redone from the root[*].
Fix this by adding the missing retry checks.
[*] I wonder if this should be done inside xas_find(), xas_next_node() and
suchlike, but I'm told that's not an simple change to effect.
This can cause an oops like that below. Note the faulting address - this
is an internal value (|0x2) returned from xarray.
BUG: kernel NULL pointer dereference, address: 0000000000000402
...
RIP: 0010:netfs_rreq_unlock+0xef/0x380 [netfs]
...
Call Trace:
netfs_rreq_assess+0xa6/0x240 [netfs]
netfs_readpage+0x173/0x3b0 [netfs]
? init_wait_var_entry+0x50/0x50
filemap_read_page+0x33/0xf0
filemap_get_pages+0x2f2/0x3f0
filemap_read+0xaa/0x320
? do_filp_open+0xb2/0x150
? rmqueue+0x3be/0xe10
ceph_read_iter+0x1fe/0x680 [ceph]
? new_sync_read+0x115/0x1a0
new_sync_read+0x115/0x1a0
vfs_read+0xf3/0x180
ksys_read+0x5f/0xe0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
Changes:
========
ver #2)
- Changed an unsigned int to a size_t to reduce the likelihood of an
overflow as per Willy's suggestion.
- Added an additional patch to fix the maths.
Fixes: 3d3c950467 ("netfs: Provide readahead and readpage netfs helpers")
Reported-by: George Law <glaw@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/166749229733.107206.17482609105741691452.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/166757987929.950645.12595273010425381286.stgit@warthog.procyon.org.uk/ # v2
check_write_begin() will unlock and put the folio when return
non-zero. So we should avoid unlocking and putting it twice in
netfs layer.
Change the way ->check_write_begin() works in the following two ways:
(1) Pass it a pointer to the folio pointer, allowing it to unlock and put
the folio prior to doing the stuff it wants to do, provided it clears
the folio pointer.
(2) Change the return values such that 0 with folio pointer set means
continue, 0 with folio pointer cleared means re-get and all error
codes indicating an error (no special treatment for -EAGAIN).
[ bagasdotme: use Sphinx code text syntax for *foliop pointer ]
Cc: stable@vger.kernel.org
Link: https://tracker.ceph.com/issues/56423
Link: https://lore.kernel.org/r/cf169f43-8ee7-8697-25da-0204d1b4343e@redhat.com
Co-developed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
The netfs_io_request cleanup op is now always in a position to be given a
pointer to a netfs_io_request struct, so this can be passed in instead of
the mapping and private data arguments (both of which are included in the
struct).
So rename the ->cleanup op to ->free_request (to match ->init_request) and
pass in the I/O pointer.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Change the signature of netfs helper functions to take a struct netfs_inode
pointer rather than a struct inode pointer where appropriate, thereby
relieving the need for the network filesystem to convert its internal inode
format down to the VFS inode only for netfslib to bounce it back up. For
type safety, it's better not to do that (and it's less typing too).
Give netfs_write_begin() an extra argument to pass in a pointer to the
netfs_inode struct rather than deriving it internally from the file
pointer. Note that the ->write_begin() and ->write_end() ops are intended
to be replaced in the future by netfslib code that manages this without the
need to call in twice for each page.
netfs_readpage() and similar are intended to be pointed at directly by the
address_space_operations table, so must stick to the signature dictated by
the function pointers there.
Changes
=======
- Updated the kerneldoc comments and documentation [DH].
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/CAHk-=wgkwKyNmNdKpQkqZ6DnmUL-x9hp0YBnUGjaPFEAdxDTbw@mail.gmail.com/
While randstruct was satisfied with using an open-coded "void *" offset
cast for the netfs_i_context <-> inode casting, __builtin_object_size() as
used by FORTIFY_SOURCE was not as easily fooled. This was causing the
following complaint[1] from gcc v12:
In file included from include/linux/string.h:253,
from include/linux/ceph/ceph_debug.h:7,
from fs/ceph/inode.c:2:
In function 'fortify_memset_chk',
inlined from 'netfs_i_context_init' at include/linux/netfs.h:326:2,
inlined from 'ceph_alloc_inode' at fs/ceph/inode.c:463:2:
include/linux/fortify-string.h:242:25: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
242 | __write_overflow_field(p_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fix this by embedding a struct inode into struct netfs_i_context (which
should perhaps be renamed to struct netfs_inode). The struct inode
vfs_inode fields are then removed from the 9p, afs, ceph and cifs inode
structs and vfs_inode is then simply changed to "netfs.inode" in those
filesystems.
Further, rename netfs_i_context to netfs_inode, get rid of the
netfs_inode() function that converted a netfs_i_context pointer to an
inode pointer (that can now be done with &ctx->inode) and rename the
netfs_i_context() function to netfs_inode() (which is now a wrapper
around container_of()).
Most of the changes were done with:
perl -p -i -e 's/vfs_inode/netfs.inode/'g \
`git grep -l 'vfs_inode' -- fs/{9p,afs,ceph,cifs}/*.[ch]`
Kees suggested doing it with a pair structure[2] and a special
declarator to insert that into the network filesystem's inode
wrapper[3], but I think it's cleaner to embed it - and then it doesn't
matter if struct randomisation reorders things.
Dave Chinner suggested using a filesystem-specific VFS_I() function in
each filesystem to convert that filesystem's own inode wrapper struct
into the VFS inode struct[4].
Version #2:
- Fix a couple of missed name changes due to a disabled cifs option.
- Rename nfs_i_context to nfs_inode
- Use "netfs" instead of "nic" as the member name in per-fs inode wrapper
structs.
[ This also undoes commit 507160f46c ("netfs: gcc-12: temporarily
disable '-Wattribute-warning' for now") that is no longer needed ]
Fixes: bc899ee1c8 ("netfs: Add a netfs inode context")
Reported-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
cc: Jonathan Corbet <corbet@lwn.net>
cc: Eric Van Hensbergen <ericvh@gmail.com>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Christian Schoenebeck <linux_oss@crudebyte.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Steve French <smfrench@gmail.com>
cc: William Kucharski <william.kucharski@oracle.com>
cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
cc: Dave Chinner <david@fromorbit.com>
cc: linux-doc@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-afs@lists.infradead.org
cc: ceph-devel@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: samba-technical@lists.samba.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-hardening@vger.kernel.org
Link: https://lore.kernel.org/r/d2ad3a3d7bdd794c6efb562d2f2b655fb67756b9.camel@kernel.org/ [1]
Link: https://lore.kernel.org/r/20220517210230.864239-1-keescook@chromium.org/ [2]
Link: https://lore.kernel.org/r/20220518202212.2322058-1-keescook@chromium.org/ [3]
Link: https://lore.kernel.org/r/20220524101205.GI2306852@dread.disaster.area/ [4]
Link: https://lore.kernel.org/r/165296786831.3591209.12111293034669289733.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165305805651.4094995.7763502506786714216.stgit@warthog.procyon.org.uk # v2
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are no more aop flags left, so remove the parameter.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
With all users of this flag gone, we can stop testing whether it's set.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
The order of these two parameters is just reversed. gcc didn't warn on
that, probably because 'void *' can be converted from or to other
pointer types without warning.
Cc: stable@vger.kernel.org
Fixes: 3d3c950467 ("netfs: Provide readahead and readpage netfs helpers")
Fixes: e1b1240c1f ("netfs: Add write_begin helper")
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Link: https://lore.kernel.org/r/20211207031449.100510-1-jefflexu@linux.alibaba.com/ # v1
Taking sb_writers whilst holding mmap_lock isn't allowed and will result in
a lockdep warning like that below. The problem comes from cachefiles
needing to take the sb_writers lock in order to do a write to the cache,
but being asked to do this by netfslib called from readpage, readahead or
write_begin[1].
Fix this by always offloading the write to the cache off to a worker
thread. The main thread doesn't need to wait for it, so deadlock can be
avoided.
This can be tested by running the quick xfstests on something like afs or
ceph with lockdep enabled.
WARNING: possible circular locking dependency detected
5.15.0-rc1-build2+ #292 Not tainted
------------------------------------------------------
holetest/65517 is trying to acquire lock:
ffff88810c81d730 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: filemap_fault+0x276/0x7a5
but task is already holding lock:
ffff8881595b53e8 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x28d/0x59c
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&mm->mmap_lock#2){++++}-{3:3}:
validate_chain+0x3c4/0x4a8
__lock_acquire+0x89d/0x949
lock_acquire+0x2dc/0x34b
__might_fault+0x87/0xb1
strncpy_from_user+0x25/0x18c
removexattr+0x7c/0xe5
__do_sys_fremovexattr+0x73/0x96
do_syscall_64+0x67/0x7a
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #1 (sb_writers#10){.+.+}-{0:0}:
validate_chain+0x3c4/0x4a8
__lock_acquire+0x89d/0x949
lock_acquire+0x2dc/0x34b
cachefiles_write+0x2b3/0x4bb
netfs_rreq_do_write_to_cache+0x3b5/0x432
netfs_readpage+0x2de/0x39d
filemap_read_page+0x51/0x94
filemap_get_pages+0x26f/0x413
filemap_read+0x182/0x427
new_sync_read+0xf0/0x161
vfs_read+0x118/0x16e
ksys_read+0xb8/0x12e
do_syscall_64+0x67/0x7a
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #0 (mapping.invalidate_lock#3){.+.+}-{3:3}:
check_noncircular+0xe4/0x129
check_prev_add+0x16b/0x3a4
validate_chain+0x3c4/0x4a8
__lock_acquire+0x89d/0x949
lock_acquire+0x2dc/0x34b
down_read+0x40/0x4a
filemap_fault+0x276/0x7a5
__do_fault+0x96/0xbf
do_fault+0x262/0x35a
__handle_mm_fault+0x171/0x1b5
handle_mm_fault+0x12a/0x233
do_user_addr_fault+0x3d2/0x59c
exc_page_fault+0x85/0xa5
asm_exc_page_fault+0x1e/0x30
other info that might help us debug this:
Chain exists of:
mapping.invalidate_lock#3 --> sb_writers#10 --> &mm->mmap_lock#2
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&mm->mmap_lock#2);
lock(sb_writers#10);
lock(&mm->mmap_lock#2);
lock(mapping.invalidate_lock#3);
*** DEADLOCK ***
1 lock held by holetest/65517:
#0: ffff8881595b53e8 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x28d/0x59c
stack backtrace:
CPU: 0 PID: 65517 Comm: holetest Not tainted 5.15.0-rc1-build2+ #292
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
Call Trace:
dump_stack_lvl+0x45/0x59
check_noncircular+0xe4/0x129
? print_circular_bug+0x207/0x207
? validate_chain+0x461/0x4a8
? add_chain_block+0x88/0xd9
? hlist_add_head_rcu+0x49/0x53
check_prev_add+0x16b/0x3a4
validate_chain+0x3c4/0x4a8
? check_prev_add+0x3a4/0x3a4
? mark_lock+0xa5/0x1c6
__lock_acquire+0x89d/0x949
lock_acquire+0x2dc/0x34b
? filemap_fault+0x276/0x7a5
? rcu_read_unlock+0x59/0x59
? add_to_page_cache_lru+0x13c/0x13c
? lock_is_held_type+0x7b/0xd3
down_read+0x40/0x4a
? filemap_fault+0x276/0x7a5
filemap_fault+0x276/0x7a5
? pagecache_get_page+0x2dd/0x2dd
? __lock_acquire+0x8bc/0x949
? pte_offset_kernel.isra.0+0x6d/0xc3
__do_fault+0x96/0xbf
? do_fault+0x124/0x35a
do_fault+0x262/0x35a
? handle_pte_fault+0x1c1/0x20d
__handle_mm_fault+0x171/0x1b5
? handle_pte_fault+0x20d/0x20d
? __lock_release+0x151/0x254
? mark_held_locks+0x1f/0x78
? rcu_read_unlock+0x3a/0x59
handle_mm_fault+0x12a/0x233
do_user_addr_fault+0x3d2/0x59c
? pgtable_bad+0x70/0x70
? rcu_read_lock_bh_held+0xab/0xab
exc_page_fault+0x85/0xa5
? asm_exc_page_fault+0x8/0x30
asm_exc_page_fault+0x1e/0x30
RIP: 0033:0x40192f
Code: ff 48 89 c3 48 8b 05 50 28 00 00 48 85 ed 7e 23 31 d2 4b 8d 0c 2f eb 0a 0f 1f 00 48 8b 05 39 28 00 00 48 0f af c2 48 83 c2 01 <48> 89 1c 01 48 39 d5 7f e8 8b 0d f2 27 00 00 31 c0 85 c9 74 0e 8b
RSP: 002b:00007f9931867eb0 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 00007f9931868700 RCX: 00007f993206ac00
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00007ffc13e06ee0
RBP: 0000000000000100 R08: 0000000000000000 R09: 00007f9931868700
R10: 00007f99318689d0 R11: 0000000000000202 R12: 00007ffc13e06ee0
R13: 0000000000000c00 R14: 00007ffc13e06e00 R15: 00007f993206a000
Fixes: 726218fdc2 ("netfs: Define an interface to talk to a cache")
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Jeff Layton <jlayton@kernel.org>
cc: Jan Kara <jack@suse.cz>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20210922110420.GA21576@quack2.suse.cz/ [1]
Link: https://lore.kernel.org/r/163887597541.1596626.2668163316598972956.stgit@warthog.procyon.org.uk/ # v1
It's not sufficient to skip reading when the pos is beyond the EOF.
There may be data at the head of the page that we need to fill in
before the write.
Add a new helper function that corrects and clarifies the logic of
when we can skip reads, and have it only zero out the part of the page
that won't have data copied in for the write.
Finally, don't set the page Uptodate after zeroing. It's not up to date
since the write data won't have been copied in yet.
[DH made the following changes:
- Prefixed the new function with "netfs_".
- Don't call zero_user_segments() for a full-page write.
- Altered the beyond-last-page check to avoid a DIV instruction and got
rid of then-redundant zero-length file check.
]
Fixes: e1b1240c1f ("netfs: Add write_begin helper")
Reported-by: Andrew W Elble <aweits@rit.edu>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
cc: ceph-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20210613233345.113565-1-jlayton@kernel.org/
Link: https://lore.kernel.org/r/162367683365.460125.4467036947364047314.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/162391826758.1173366.11794946719301590013.stgit@warthog.procyon.org.uk/ # v2
Fix some miscellaneous things in the new netfs lib[1]:
(1) The kerneldoc for netfs_readpage() shouldn't say netfs_page().
(2) netfs_readpage() can get an integer overflow on 32-bit when it
multiplies page_index(page) by PAGE_SIZE. It should use
page_file_offset() instead.
(3) netfs_write_begin() should use page_offset() to avoid the same
overflow.
Note that netfs_readpage() needs to use page_file_offset() rather than
page_offset() as it may see swap-over-NFS.
Reported-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/161789062190.6155.12711584466338493050.stgit@warthog.procyon.org.uk/ [1]
Linus Torvalds