| Age | Commit message (Collapse) | Author |
|---|
|
The current iomap_iter iteration model reads the mapping from the
filesystem, processes the subrange of the operation associated with
the current mapping, and returns the number of bytes processed back
to the iteration code. The latter advances the position and
remaining length of the iter in preparation for the next iteration.
At the _iter() handler level, this tends to produce a processing
loop where the local code pulls the current position and remaining
length out of the iter, iterates it locally based on file offset,
and then breaks out when the associated range has been fully
processed.
This works well enough for current handlers, but upcoming
enhancements require a bit more flexibility in certain situations.
Enhancements for zero range will lead to a situation where the
processing loop is no longer a pure ascending offset walk, but
rather dictated by pagecache state and folio lookup. Since folio
lookup and write preparation occur at different levels, it is more
difficult to manage position and length outside of the iter.
To provide more flexibility to certain iomap operations, introduce
support for incremental iomap_iter advances from within the
operation itself. This allows more granular advances for operations
that might not use the typical file offset based walk.
Note that the semantics for operations that use incremental advances
is slightly different than traditional operations. Operations that
advance the iter directly are expected to return success or failure
(i.e. 0 or negative error code) in iter.processed rather than the
number of bytes processed.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-8-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
As a final step for generic iter advance, export the helper and
update it to return the remaining length of the current iteration
after the advance. This will usually be 0 in the iomap_iter() case,
but will be useful for the various operations that iterate on their
own and will be updated to advance as they progress.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-7-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
The iter termination logic in iomap_iter_advance() is only needed by
iomap_iter() to determine whether to proceed with the next mapping
for an ongoing operation. The old logic sets ret to 1 and then
terminates if the operation is complete (iter->len == 0) or the
previous iteration performed no work and the mapping has not been
marked stale. The stale check exists to allow operations to
retry the current mapping if an inconsistency has been detected.
To further genericize iomap_iter_advance(), lift the termination
logic into iomap_iter() and update the former to return success (0)
or an error code. iomap_iter() continues on successful advance and
non-zero iter->len or otherwise terminates in the no progress (and
not stale) or error cases.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-6-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
The error code is only used to check whether iomap_iter() should
terminate due to an error returned in iter.processed. Lift the check
out of iomap_iter_advance() in preparation to make it more generic.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-5-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
iomap_iter() checks iomap.length to skip individual code blocks not
appropriate for the initial case where there is no mapping in the
iter. To prepare for upcoming changes, refactor the code to jump
straight to the ->iomap_begin() handler in the initial case and move
the tracepoint to the top of the function so it always executes.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-4-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
In preparation for more granular iomap_iter advancing, break out
some of the logic associated with higher level iteration from
iomap_advance_iter(). Specifically, factor the iomap reset code into
a separate helper and lift the iomap.length check into the calling
code, similar to how ->iomap_end() calls are handled.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-3-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Allow the file system to pass private data which can be used by the
iomap_begin and iomap_end methods through the private pointer in the
iomap_iter structure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-12-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Allow the file system to pass private data which can be used by the
iomap_begin and iomap_end methods through the private pointer in the
iomap_iter structure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-11-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Allow the file system to pass private data which can be used by the
iomap_begin and iomap_end methods through the private pointer in the
iomap_iter structure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-10-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Add a private data field to struct iomap_ioend so that the file system
can attach information to it. Zoned XFS will use this for a pointer to
the open zone.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-9-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
struct iomap_ioend currently tracks outstanding buffered writes and has
some really nice code in core iomap and XFS to merge contiguous I/Os
an defer them to userspace for completion in a very efficient way.
For zoned writes we'll also need a per-bio user context completion to
record the written blocks, and the infrastructure for that would look
basically like the ioend handling for buffered I/O.
So instead of reinventing the wheel, reuse the existing infrastructure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-8-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Split out the struct iomap-dio level final completion from
iomap_dio_bio_end_io into a helper to clean up the code and make it
reusable.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-7-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
This code will be reused for direct I/O soon, so split it out of
buffered-io.c.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-6-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Provide helpers for file systems to split bios in the direct I/O and
writeback I/O submission handlers. The split ioends are chained to
the parent ioend so that only the parent ioend originally generated
by the iomap layer will be processed after all the chained off children
have completed. This is based on the block layer bio chaining that has
supported a similar mechanism for a long time.
This Follows btrfs' lead and don't try to build bios to hardware limits
for zone append commands, but instead build them as normal unconstrained
bios and split them to the hardware limits in the I/O submission handler.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-5-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Add a IOMAP_F_ANON_WRITE flag that indicates that the write I/O does not
have a target block assigned to it yet at iomap time and the file system
will do that in the bio submission handler, splitting the I/O as needed.
This is used to implement Zone Append based I/O for zoned XFS, where
splitting writes to the hardware limits and assigning a zone to them
happens just before sending the I/O off to the block layer, but could
also be useful for other things like compressed I/O.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-4-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
The ioend fields for distinct types of I/O are a bit complicated.
Consolidate them into a single io_flag field with it's own flags
decoupled from the iomap flags. This also prepares for adding a new
flag that is unrelated to both of the iomap namespaces.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-3-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Change ->prepare_ioend to ->submit_ioend and require file systems that
implement it to submit the bio. This is needed for file systems that
do their own work on the bios before submitting them to the block layer
like btrfs or zoned xfs. To make this easier also pass the writeback
context to the method.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-2-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"The various patchsets are summarized below. Plus of course many
indivudual patches which are described in their changelogs.
- "Allocate and free frozen pages" from Matthew Wilcox reorganizes
the page allocator so we end up with the ability to allocate and
free zero-refcount pages. So that callers (ie, slab) can avoid a
refcount inc & dec
- "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
use large folios other than PMD-sized ones
- "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
and fixes for this small built-in kernel selftest
- "mas_anode_descend() related cleanup" from Wei Yang tidies up part
of the mapletree code
- "mm: fix format issues and param types" from Keren Sun implements a
few minor code cleanups
- "simplify split calculation" from Wei Yang provides a few fixes and
a test for the mapletree code
- "mm/vma: make more mmap logic userland testable" from Lorenzo
Stoakes continues the work of moving vma-related code into the
(relatively) new mm/vma.c
- "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
Hildenbrand cleans up and rationalizes handling of gfp flags in the
page allocator
- "readahead: Reintroduce fix for improper RA window sizing" from Jan
Kara is a second attempt at fixing a readahead window sizing issue.
It should reduce the amount of unnecessary reading
- "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
addresses an issue where "huge" amounts of pte pagetables are
accumulated:
https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/
Qi's series addresses this windup by synchronously freeing PTE
memory within the context of madvise(MADV_DONTNEED)
- "selftest/mm: Remove warnings found by adding compiler flags" from
Muhammad Usama Anjum fixes some build warnings in the selftests
code when optional compiler warnings are enabled
- "mm: don't use __GFP_HARDWALL when migrating remote pages" from
David Hildenbrand tightens the allocator's observance of
__GFP_HARDWALL
- "pkeys kselftests improvements" from Kevin Brodsky implements
various fixes and cleanups in the MM selftests code, mainly
pertaining to the pkeys tests
- "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
estimate application working set size
- "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
provides some cleanups to memcg's hugetlb charging logic
- "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
removes the global swap cgroup lock. A speedup of 10% for a
tmpfs-based kernel build was demonstrated
- "zram: split page type read/write handling" from Sergey Senozhatsky
has several fixes and cleaups for zram in the area of
zram_write_page(). A watchdog softlockup warning was eliminated
- "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
Brodsky cleans up the pagetable destructor implementations. A rare
use-after-free race is fixed
- "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
simplifies and cleans up the debugging code in the VMA merging
logic
- "Account page tables at all levels" from Kevin Brodsky cleans up
and regularizes the pagetable ctor/dtor handling. This results in
improvements in accounting accuracy
- "mm/damon: replace most damon_callback usages in sysfs with new
core functions" from SeongJae Park cleans up and generalizes
DAMON's sysfs file interface logic
- "mm/damon: enable page level properties based monitoring" from
SeongJae Park increases the amount of information which is
presented in response to DAMOS actions
- "mm/damon: remove DAMON debugfs interface" from SeongJae Park
removes DAMON's long-deprecated debugfs interfaces. Thus the
migration to sysfs is completed
- "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
Peter Xu cleans up and generalizes the hugetlb reservation
accounting
- "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
removes a never-used feature of the alloc_pages_bulk() interface
- "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
extends DAMOS filters to support not only exclusion (rejecting),
but also inclusion (allowing) behavior
- "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
introduces a new memory descriptor for zswap.zpool that currently
overlaps with struct page for now. This is part of the effort to
reduce the size of struct page and to enable dynamic allocation of
memory descriptors
- "mm, swap: rework of swap allocator locks" from Kairui Song redoes
and simplifies the swap allocator locking. A speedup of 400% was
demonstrated for one workload. As was a 35% reduction for kernel
build time with swap-on-zram
- "mm: update mips to use do_mmap(), make mmap_region() internal"
from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
mmap_region() can be made MM-internal
- "mm/mglru: performance optimizations" from Yu Zhao fixes a few
MGLRU regressions and otherwise improves MGLRU performance
- "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
Park updates DAMON documentation
- "Cleanup for memfd_create()" from Isaac Manjarres does that thing
- "mm: hugetlb+THP folio and migration cleanups" from David
Hildenbrand provides various cleanups in the areas of hugetlb
folios, THP folios and migration
- "Uncached buffered IO" from Jens Axboe implements the new
RWF_DONTCACHE flag which provides synchronous dropbehind for
pagecache reading and writing. To permite userspace to address
issues with massive buildup of useless pagecache when
reading/writing fast devices
- "selftests/mm: virtual_address_range: Reduce memory" from Thomas
Weißschuh fixes and optimizes some of the MM selftests"
* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
mm/compaction: fix UBSAN shift-out-of-bounds warning
s390/mm: add missing ctor/dtor on page table upgrade
kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
tools: add VM_WARN_ON_VMG definition
mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
seqlock: add missing parameter documentation for raw_seqcount_try_begin()
mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
mm/page_alloc: remove the incorrect and misleading comment
zram: remove zcomp_stream_put() from write_incompressible_page()
mm: separate move/undo parts from migrate_pages_batch()
mm/kfence: use str_write_read() helper in get_access_type()
selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
selftests/mm: vm_util: split up /proc/self/smaps parsing
selftests/mm: virtual_address_range: unmap chunks after validation
selftests/mm: virtual_address_range: mmap() without PROT_WRITE
selftests/memfd/memfd_test: fix possible NULL pointer dereference
mm: add FGP_DONTCACHE folio creation flag
mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
...
|
|
Remove highest_bit and lowest_bit. After the HDD allocation path has been
removed, the only purpose of these two fields is to determine whether the
device is full or not, which can instead be determined by checking the
inuse_pages.
Link: https://lkml.kernel.org/r/20250113175732.48099-6-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chis Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
on 32-bit kernels, iomap_write_delalloc_scan() was inadvertently using a
32-bit position due to folio_next_index() returning an unsigned long.
This could lead to an infinite loop when writing to an xfs filesystem.
Signed-off-by: Marco Nelissen <marco.nelissen@gmail.com>
Link: https://lore.kernel.org/r/20250109041253.2494374-1-marco.nelissen@gmail.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
During concurrent append writes to XFS filesystem, zero padding data
may appear in the file after power failure. This happens due to imprecise
disk size updates when handling write completion.
Consider this scenario with concurrent append writes same file:
Thread 1: Thread 2:
------------ -----------
write [A, A+B]
update inode size to A+B
submit I/O [A, A+BS]
write [A+B, A+B+C]
update inode size to A+B+C
<I/O completes, updates disk size to min(A+B+C, A+BS)>
<power failure>
After reboot:
1) with A+B+C < A+BS, the file has zero padding in range [A+B, A+B+C]
|< Block Size (BS) >|
|DDDDDDDDDDDDDDDD0000000000000000|
^ ^ ^
A A+B A+B+C
(EOF)
2) with A+B+C > A+BS, the file has zero padding in range [A+B, A+BS]
|< Block Size (BS) >|< Block Size (BS) >|
|DDDDDDDDDDDDDDDD0000000000000000|00000000000000000000000000000000|
^ ^ ^ ^
A A+B A+BS A+B+C
(EOF)
D = Valid Data
0 = Zero Padding
The issue stems from disk size being set to min(io_offset + io_size,
inode->i_size) at I/O completion. Since io_offset+io_size is block
size granularity, it may exceed the actual valid file data size. In
the case of concurrent append writes, inode->i_size may be larger
than the actual range of valid file data written to disk, leading to
inaccurate disk size updates.
This patch modifies the meaning of io_size to represent the size of
valid data within EOF in an ioend. If the ioend spans beyond i_size,
io_size will be trimmed to provide the file with more accurate size
information. This is particularly useful for on-disk size updates
at completion time.
After this change, ioends that span i_size will not grow or merge with
other ioends in concurrent scenarios. However, these cases that need
growth/merging rarely occur and it seems no noticeable performance impact.
Although rounding up io_size could enable ioend growth/merging in these
scenarios, we decided to keep the code simple after discussion [1].
Another benefit is that it makes the xfs_ioend_is_append() check more
accurate, which can reduce unnecessary end bio callbacks of xfs_end_bio()
in certain scenarios, such as repeated writes at the file tail without
extending the file size.
Link [1]: https://patchwork.kernel.org/project/xfs/patch/20241113091907.56937-1-leo.lilong@huawei.com
Fixes: ae259a9c8593 ("fs: introduce iomap infrastructure") # goes further back than this
Signed-off-by: Long Li <leo.lilong@huawei.com>
Link: https://lore.kernel.org/r/20241209114241.3725722-3-leo.lilong@huawei.com
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
This is a preparatory patch for fixing zero padding issues in concurrent
append write scenarios. In the following patches, we need to obtain
byte-granular writeback end position for io_size trimming after EOF
handling.
Due to concurrent writeback and truncate operations, inode size may
shrink. Resampling inode size would force writeback code to handle the
newly appeared post-EOF blocks, which is undesirable. As Dave
explained in [1]:
"Really, the issue is that writeback mappings have to be able to
handle the range being mapped suddenly appear to be beyond EOF.
This behaviour is a longstanding writeback constraint, and is what
iomap_writepage_handle_eof() is attempting to handle.
We handle this by only sampling i_size_read() whilst we have the
folio locked and can determine the action we should take with that
folio (i.e. nothing, partial zeroing, or skip altogether). Once
we've made the decision that the folio is within EOF and taken
action on it (i.e. moved the folio to writeback state), we cannot
then resample the inode size because a truncate may have started
and changed the inode size."
To avoid resampling inode size after EOF handling, we convert end_pos
to byte-granular writeback position and return it from EOF handling
function.
Since iomap_set_range_dirty() can handle unaligned lengths, this
conversion has no impact on it. However, iomap_find_dirty_range()
requires aligned start and end range to find dirty blocks within the
given range, so the end position needs to be rounded up when passed
to it.
LINK [1]: https://lore.kernel.org/linux-xfs/Z1Gg0pAa54MoeYME@localhost.localdomain/
Signed-off-by: Long Li <leo.lilong@huawei.com>
Link: https://lore.kernel.org/r/20241209114241.3725722-2-leo.lilong@huawei.com
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Bring in an overlayfs fix for v6.13-rc1 that fixes a bug introduced by
the overlayfs changes merged for v6.13.
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Pull xfs updates from Carlos Maiolino:
"The bulk of this pull request is a major rework that Darrick and
Christoph have been doing on XFS's real-time volume, coupled with a
few features to support this rework. It does also includes some bug
fixes.
- convert perag to use xarrays
- create a new generic allocation group structure
- add metadata inode dir trees
- create in-core rt allocation groups
- shard the RT section into allocation groups
- persist quota options with the enw metadata dir tree
- enable quota for RT volumes
- enable metadata directory trees
- some bugfixes"
* tag 'xfs-6.13-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (146 commits)
xfs: port ondisk structure checks from xfs/122 to the kernel
xfs: separate space btree structures in xfs_ondisk.h
xfs: convert struct typedefs in xfs_ondisk.h
xfs: enable metadata directory feature
xfs: enable realtime quota again
xfs: update sb field checks when metadir is turned on
xfs: reserve quota for realtime files correctly
xfs: create quota preallocation watermarks for realtime quota
xfs: report realtime block quota limits on realtime directories
xfs: persist quota flags with metadir
xfs: advertise realtime quota support in the xqm stat files
xfs: scrub quota file metapaths
xfs: fix chown with rt quota
xfs: use metadir for quota inodes
xfs: refactor xfs_qm_destroy_quotainos
xfs: use rtgroup busy extent list for FITRIM
xfs: implement busy extent tracking for rtgroups
xfs: port the perag discard code to handle generic groups
xfs: move the min and max group block numbers to xfs_group
xfs: adjust min_block usage in xfs_verify_agbno
...
|
|
iomap zero range flushes pagecache in certain situations to
determine which parts of the range might require zeroing if dirty
data is present in pagecache. The kernel robot recently reported a
regression associated with this flushing in the following stress-ng
workload on XFS:
stress-ng --timeout 60 --times --verify --metrics --no-rand-seed --metamix 64
This workload involves repeated small, strided, extending writes. On
XFS, this produces a pattern of post-eof speculative preallocation,
conversion of preallocation from delalloc to unwritten, dirtying
pagecache over newly unwritten blocks, and then rinse and repeat
from the new EOF. This leads to repetitive flushing of the EOF folio
via the zero range call XFS uses for writes that start beyond
current EOF.
To mitigate this problem, special case EOF block zeroing to prefer
zeroing the folio over a flush when the EOF folio is already dirty.
To do this, split out and open code handling of an unaligned start
offset. This brings most of the performance back by avoiding flushes
on zero range calls via write and truncate extension operations. The
flush doesn't occur in these situations because the entire range is
post-eof and therefore the folio that overlaps EOF is the only one
in the range.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20241115200155.593665-4-bfoster@redhat.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
In preparation for special handling of subranges, lift the zeroed
mapping logic from the iterator into the caller. Since this puts the
pagecache dirty check and flushing in the same place, streamline the
comments a bit as well.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20241115200155.593665-3-bfoster@redhat.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
iomap_iter_advance() zeroes the processed and mapping fields on
every non-error iteration except for the last expected iteration
(i.e. return 0 expected to terminate the iteration loop). This
appears to be circumstantial as nothing currently relies on these
fields after the final iteration.
Therefore to better faciliate iomap_iter reuse in subsequent
patches, update iomap_iter_advance() to always reset per-iteration
state on successful completion.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20241115200155.593665-2-bfoster@redhat.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
iomap_zero_range() uses buffered writes for manual zeroing, no
longer updates i_size for such writes, but is still explicitly
called for post-eof ranges. The historical use case for this is
zeroing post-eof speculative preallocation on extending writes from
XFS. However, XFS also recently changed to convert all post-eof
delalloc mappings to unwritten in the iomap_begin() handler, which
means it now never expects manual zeroing of post-eof mappings. In
other words, all post-eof mappings should be reported as holes or
unwritten.
This is a subtle dependency that can be hard to detect if violated
because associated codepaths are likely to update i_size after folio
locks are dropped, but before writeback happens to occur. For
example, if XFS reverts back to some form of manual zeroing of
post-eof blocks on write extension, writeback of those zeroed folios
will now race with the presumed i_size update from the subsequent
buffered write.
Since iomap_zero_range() can't correctly zero post-eof mappings
beyond EOF without updating i_size, warn if this ever occurs. This
serves as minimal indication that if this use case is reintroduced
by a filesystem, iomap_zero_range() might need to reconsider i_size
updates for write extending use cases.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20241115145931.535207-1-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs untorn write support from Christian Brauner:
"An atomic write is a write issed with torn-write protection. This
means for a power failure or any hardware failure all or none of the
data from the write will be stored, never a mix of old and new data.
This work is already supported for block devices. If a block device is
opened with O_DIRECT and the block device supports atomic write, then
FMODE_CAN_ATOMIC_WRITE is added to the file of the opened block
device.
This contains the work to expand atomic write support to filesystems,
specifically ext4 and XFS. Currently, only support for writing exactly
one filesystem block atomically is added.
Since it's now possible to have filesystem block size > page size for
XFS, it's possible to write 4K+ blocks atomically on x86"
* tag 'vfs-6.13.untorn.writes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
iomap: drop an obsolete comment in iomap_dio_bio_iter
ext4: Do not fallback to buffered-io for DIO atomic write
ext4: Support setting FMODE_CAN_ATOMIC_WRITE
ext4: Check for atomic writes support in write iter
ext4: Add statx support for atomic writes
xfs: Support setting FMODE_CAN_ATOMIC_WRITE
xfs: Validate atomic writes
xfs: Support atomic write for statx
fs: iomap: Atomic write support
fs: Export generic_atomic_write_valid()
block: Add bdev atomic write limits helpers
fs/block: Check for IOCB_DIRECT in generic_atomic_write_valid()
block/fs: Pass an iocb to generic_atomic_write_valid()
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Features:
- Fixup and improve NLM and kNFSD file lock callbacks
Last year both GFS2 and OCFS2 had some work done to make their
locking more robust when exported over NFS. Unfortunately, part of
that work caused both NLM (for NFS v3 exports) and kNFSD (for
NFSv4.1+ exports) to no longer send lock notifications to clients
This in itself is not a huge problem because most NFS clients will
still poll the server in order to acquire a conflicted lock
It's important for NLM and kNFSD that they do not block their
kernel threads inside filesystem's file_lock implementations
because that can produce deadlocks. We used to make sure of this by
only trusting that posix_lock_file() can correctly handle blocking
lock calls asynchronously, so the lock managers would only setup
their file_lock requests for async callbacks if the filesystem did
not define its own lock() file operation
However, when GFS2 and OCFS2 grew the capability to correctly
handle blocking lock requests asynchronously, they started
signalling this behavior with EXPORT_OP_ASYNC_LOCK, and the check
for also trusting posix_lock_file() was inadvertently dropped, so
now most filesystems no longer produce lock notifications when
exported over NFS
Fix this by using an fop_flag which greatly simplifies the problem
and grooms the way for future uses by both filesystems and lock
managers alike
- Add a sysctl to delete the dentry when a file is removed instead of
making it a negative dentry
Commit 681ce8623567 ("vfs: Delete the associated dentry when
deleting a file") introduced an unconditional deletion of the
associated dentry when a file is removed. However, this led to
performance regressions in specific benchmarks, such as
ilebench.sum_operations/s, prompting a revert in commit
4a4be1ad3a6e ("Revert "vfs: Delete the associated dentry when
deleting a file""). This reintroduces the concept conditionally
through a sysctl
- Expand the statmount() system call:
* Report the filesystem subtype in a new fs_subtype field to
e.g., report fuse filesystem subtypes
* Report the superblock source in a new sb_source field
* Add a new way to return filesystem specific mount options in an
option array that returns filesystem specific mount options
separated by zero bytes and unescaped. This allows caller's to
retrieve filesystem specific mount options and immediately pass
them to e.g., fsconfig() without having to unescape or split
them
* Report security (LSM) specific mount options in a separate
security option array. We don't lump them together with
filesystem specific mount options as security mount options are
generic and most users aren't interested in them
The format is the same as for the filesystem specific mount
option array
- Support relative paths in fsconfig()'s FSCONFIG_SET_STRING command
- Optimize acl_permission_check() to avoid costly {g,u}id ownership
checks if possible
- Use smp_mb__after_spinlock() to avoid full smp_mb() in evict()
- Add synchronous wakeup support for ep_poll_callback.
Currently, epoll only uses wake_up() to wake up task. But sometimes
there are epoll users which want to use the synchronous wakeup flag
to give a hint to the scheduler, e.g., the Android binder driver.
So add a wake_up_sync() define, and use wake_up_sync() when sync is
true in ep_poll_callback()
Fixes:
- Fix kernel documentation for inode_insert5() and iget5_locked()
- Annotate racy epoll check on file->f_ep
- Make F_DUPFD_QUERY associative
- Avoid filename buffer overrun in initramfs
- Don't let statmount() return empty strings
- Add a cond_resched() to dump_user_range() to avoid hogging the CPU
- Don't query the device logical blocksize multiple times for hfsplus
- Make filemap_read() check that the offset is positive or zero
Cleanups:
- Various typo fixes
- Cleanup wbc_attach_fdatawrite_inode()
- Add __releases annotation to wbc_attach_and_unlock_inode()
- Add hugetlbfs tracepoints
- Fix various vfs kernel doc parameters
- Remove obsolete TODO comment from io_cancel()
- Convert wbc_account_cgroup_owner() to take a folio
- Fix comments for BANDWITH_INTERVAL and wb_domain_writeout_add()
- Reorder struct posix_acl to save 8 bytes
- Annotate struct posix_acl with __counted_by()
- Replace one-element array with flexible array member in freevxfs
- Use idiomatic atomic64_inc_return() in alloc_mnt_ns()"
* tag 'vfs-6.13.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
statmount: retrieve security mount options
vfs: make evict() use smp_mb__after_spinlock instead of smp_mb
statmount: add flag to retrieve unescaped options
fs: add the ability for statmount() to report the sb_source
writeback: wbc_attach_fdatawrite_inode out of line
writeback: add a __releases annoation to wbc_attach_and_unlock_inode
fs: add the ability for statmount() to report the fs_subtype
fs: don't let statmount return empty strings
fs:aio: Remove TODO comment suggesting hash or array usage in io_cancel()
hfsplus: don't query the device logical block size multiple times
freevxfs: Replace one-element array with flexible array member
fs: optimize acl_permission_check()
initramfs: avoid filename buffer overrun
fs/writeback: convert wbc_account_cgroup_owner to take a folio
acl: Annotate struct posix_acl with __counted_by()
acl: Realign struct posix_acl to save 8 bytes
epoll: Add synchronous wakeup support for ep_poll_callback
coredump: add cond_resched() to dump_user_range
mm/page-writeback.c: Fix comment of wb_domain_writeout_add()
mm/page-writeback.c: Update comment for BANDWIDTH_INTERVAL
...
|
|
No more zone append special casing in iomap for quite a while.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241111121340.1390540-1-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
File systems might have boundaries over which merges aren't possible.
In fact these are very common, although most of the time some kind of
header at the beginning of this region (e.g. XFS alloation groups, ext4
block groups) automatically create a merge barrier. But if that is
not present, say for a device purely used for data we need to manually
communicate that to iomap.
Add a IOMAP_F_BOUNDARY flag to never merge I/O into a previous mapping.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
|
|
Support direct I/O atomic writes by producing a single bio with REQ_ATOMIC
flag set.
Initially FSes (XFS) should only support writing a single FS block
atomically.
As with any atomic write, we should produce a single bio which covers the
complete write length.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
[djwong: clarify a couple of things in the docs]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
|
|
gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull iomap fixes from Christian Brauner:
"Fixes for iomap to prevent data corruption bugs in the fallocate
unshare range implementation of fsdax and a small cleanup to turn
iomap_want_unshare_iter() into an inline function"
* tag 'vfs-6.12-rc6.iomap' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
iomap: turn iomap_want_unshare_iter into an inline function
fsdax: dax_unshare_iter needs to copy entire blocks
fsdax: remove zeroing code from dax_unshare_iter
iomap: share iomap_unshare_iter predicate code with fsdax
xfs: don't allocate COW extents when unsharing a hole
|
|
Most of the callers of wbc_account_cgroup_owner() are converting a folio
to page before calling the function. wbc_account_cgroup_owner() is
converting the page back to a folio to call mem_cgroup_css_from_folio().
Convert wbc_account_cgroup_owner() to take a folio instead of a page,
and convert all callers to pass a folio directly except f2fs.
Convert the page to folio for all the callers from f2fs as they were the
only callers calling wbc_account_cgroup_owner() with a page. As f2fs is
already in the process of converting to folios, these call sites might
also soon be calling wbc_account_cgroup_owner() with a folio directly in
the future.
No functional changes. Only compile tested.
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Link: https://lore.kernel.org/r/20240926140121.203821-1-kernel@pankajraghav.com
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
iomap_want_unshare_iter currently sits in fs/iomap/buffered-io.c, which
depends on CONFIG_BLOCK. It is also in used in fs/dax.c whіch has no
such dependency. Given that it is a trivial check turn it into an inline
in include/linux/iomap.h to fix the DAX && !BLOCK build.
Fixes: 6ef6a0e821d3 ("iomap: share iomap_unshare_iter predicate code with fsdax")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241015041350.118403-1-hch@lst.de
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
XFS (which currently is the only user of iomap_write_delalloc_release)
already holds invalidate_lock for most zeroing operations. To be able
to avoid a deadlock it needs to stop taking the lock, but doing so
in iomap would leak XFS locking details into iomap.
To avoid this require the caller to hold invalidate_lock when calling
iomap_write_delalloc_release instead of taking it there.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
|
|
Currently iomap_file_buffered_write_punch_delalloc can be called from
XFS either with the invalidate lock held or not. To fix this while
keeping the locking in the file system and not the iomap library
code we'll need to life the locking up into the file system.
To prepare for that, open code iomap_file_buffered_write_punch_delalloc
in the only caller, and instead export iomap_write_delalloc_release.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
|
|
Split out a pice of logic from iomap_file_buffered_write_punch_delalloc
that is useful for all iomap_end implementations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
|
|
The predicate code that iomap_unshare_iter uses to decide if it's really
needs to unshare a file range mapping should be shared with the fsdax
version, because right now they're opencoded and inconsistent.
Note that we simplify the predicate logic a bit -- we no longer allow
unsharing of inline data mappings, but there aren't any filesystems that
allow shared inline data currently.
This is a fix in the sense that it should have been ported to fsdax.
Fixes: b53fdb215d13 ("iomap: improve shared block detection in iomap_unshare_iter")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/172796813294.1131942.15762084021076932620.stgit@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
File contents can only be shared (i.e. reflinked) below EOF, so it makes
no sense to try to unshare ranges beyond EOF. Constrain the file range
parameters here so that we don't have to do that in the callers.
Fixes: 5f4e5752a8a3 ("fs: add iomap_file_dirty")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20241002150213.GC21853@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
If unshare encounters a delalloc reservation in the srcmap, that means
that the file range isn't shared because delalloc reservations cannot be
reflinked. Therefore, don't try to unshare them.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20241002150040.GB21853@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull vfs blocksize updates from Christian Brauner:
"This contains the vfs infrastructure as well as the xfs bits to enable
support for block sizes (bs) larger than page sizes (ps) plus a few
fixes to related infrastructure.
There has been efforts over the last 16 years to enable enable Large
Block Sizes (LBS), that is block sizes in filesystems where bs > page
size. Through these efforts we have learned that one of the main
blockers to supporting bs > ps in filesystems has been a way to
allocate pages that are at least the filesystem block size on the page
cache where bs > ps.
Thanks to various previous efforts it is possible to support bs > ps
in XFS with only a few changes in XFS itself. Most changes are to the
page cache to support minimum order folio support for the target block
size on the filesystem.
A motivation for Large Block Sizes today is to support high-capacity
(large amount of Terabytes) QLC SSDs where the internal Indirection
Unit (IU) are typically greater than 4k to help reduce DRAM and so in
turn cost and space. In practice this then allows different
architectures to use a base page size of 4k while still enabling
support for block sizes aligned to the larger IUs by relying on high
order folios on the page cache when needed.
It also allows to take advantage of the drive's support for atomics
larger than 4k with buffered IO support in Linux. As described this
year at LSFMM, supporting large atomics greater than 4k enables
databases to remove the need to rely on their own journaling, so they
can disable double buffered writes, which is a feature different cloud
providers are already enabling through custom storage solutions"
* tag 'vfs-6.12.blocksize' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (22 commits)
Documentation: iomap: fix a typo
iomap: remove the iomap_file_buffered_write_punch_delalloc return value
iomap: pass the iomap to the punch callback
iomap: pass flags to iomap_file_buffered_write_punch_delalloc
iomap: improve shared block detection in iomap_unshare_iter
iomap: handle a post-direct I/O invalidate race in iomap_write_delalloc_release
docs:filesystems: fix spelling and grammar mistakes in iomap design page
filemap: fix htmldoc warning for mapping_align_index()
iomap: make zero range flush conditional on unwritten mappings
iomap: fix handling of dirty folios over unwritten extents
iomap: add a private argument for iomap_file_buffered_write
iomap: remove set_memor_ro() on zero page
xfs: enable block size larger than page size support
xfs: make the calculation generic in xfs_sb_validate_fsb_count()
xfs: expose block size in stat
xfs: use kvmalloc for xattr buffers
iomap: fix iomap_dio_zero() for fs bs > system page size
filemap: cap PTE range to be created to allowed zero fill in folio_map_range()
mm: split a folio in minimum folio order chunks
readahead: allocate folios with mapping_min_order in readahead
...
|
|
iomap_file_buffered_write_punch_delalloc can only return errors if either
the ->punch callback returned an error, or if someone changed the API of
mapping_seek_hole_data to return a negative error code that is not
-ENXIO.
As the only instance of ->punch never returns an error, an such an error
would be fatal anyway remove the entire error propagation and don't
return an error code from iomap_file_buffered_write_punch_delalloc.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240910043949.3481298-6-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
XFS will need to look at the flags in the iomap structure, so pass it
down all the way to the callback.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240910043949.3481298-5-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
To fix short write error handling, We'll need to figure out what operation
iomap_file_buffered_write_punch_delalloc is called for. Pass the flags
argument on to it, and reorder the argument list to match that of
->iomap_end so that the compiler only has to add the new punch argument
to the end of it instead of reshuffling the registers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240910043949.3481298-4-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Currently iomap_unshare_iter relies on the IOMAP_F_SHARED flag to detect
blocks to unshare. This is reasonable, but IOMAP_F_SHARED is also useful
for the file system to do internal book keeping for out of place writes.
XFS used to that, until it got removed in commit 72a048c1056a
("xfs: only set IOMAP_F_SHARED when providing a srcmap to a write")
because unshare for incorrectly unshare such blocks.
Add an extra safeguard by checking the explicitly provided srcmap instead
of the fallback to the iomap for valid data, as that catches the case
where we'd just copy from the same place we'd write to easily, allowing
to reinstate setting IOMAP_F_SHARED for all XFS writes that go to the
COW fork.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240910043949.3481298-3-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
When direct I/O completions invalidates the page cache it holds neither the
i_rwsem nor the invalidate_lock so it can be racing with
iomap_write_delalloc_release. If the search for the end of the region that
contains data returns the start offset we hit such a race and just need to
look for the end of the newly created hole instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240910043949.3481298-2-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
iomap_zero_range() flushes pagecache to mitigate consistency
problems with dirty pagecache and unwritten mappings. The flush is
unconditional over the entire range because checking pagecache state
after mapping lookup is racy with writeback and reclaim. There are
ways around this using iomap's mapping revalidation mechanism, but
this is not supported by all iomap based filesystems and so is not a
generic solution.
There is another way around this limitation that is good enough to
filter the flush for most cases in practice. If we check for dirty
pagecache over the target range (instead of unconditionally flush),
we can keep track of whether the range was dirty before lookup and
defer the flush until/unless we see a combination of dirty cache
backed by an unwritten mapping. We don't necessarily know whether
the dirty cache was backed by the unwritten maping or some other
(written) part of the range, but the impliciation of a false
positive here is a spurious flush and thus relatively harmless.
Note that we also flush for hole mappings because iomap_zero_range()
is used for partial folio zeroing in some cases. For example, if a
folio straddles EOF on a sub-page FSB size fs, the post-eof portion
is hole-backed and dirtied/written via mapped write, and then i_size
increases before writeback can occur (which otherwise zeroes the
post-eof portion of the EOF folio), then the folio becomes
inconsistent with disk until reclaimed. A flush in this case
executes partial zeroing from writeback, and iomap knows that there
is otherwise no I/O to submit for hole backed mappings.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20240830145634.138439-3-bfoster@redhat.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
The iomap zero range implementation doesn't properly handle dirty
pagecache over unwritten mappings. It skips such mappings as if they
were pre-zeroed. If some part of an unwritten mapping is dirty in
pagecache from a previous write, the data in cache should be zeroed
as well. Instead, the data is left in cache and creates a stale data
exposure problem if writeback occurs sometime after the zero range.
Most callers are unaffected by this because the higher level
filesystem contexts that call zero range typically perform a filemap
flush of the target range for other reasons. A couple contexts that
don't otherwise need to flush are write file size extension and
truncate in XFS. The former path is currently susceptible to the
stale data exposure problem and the latter performs a flush
specifically to work around it.
This is clearly inconsistent and incomplete. As a first step toward
correcting behavior, lift the XFS workaround to iomap_zero_range()
and unconditionally flush the range before the zero range operation
proceeds. While this appears to be a bit of a big hammer, most all
users already do this from calling context save for the couple of
exceptions noted above. Future patches will optimize or elide this
flush while maintaining functional correctness.
Fixes: ae259a9c8593 ("fs: introduce iomap infrastructure")
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20240830145634.138439-2-bfoster@redhat.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
