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Merge tag 'vfs-6.19-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs inode updates from Christian Brauner:
"Features:
- Hide inode->i_state behind accessors. Open-coded accesses prevent
asserting they are done correctly. One obvious aspect is locking,
but significantly more can be checked. For example it can be
detected when the code is clearing flags which are already missing,
or is setting flags when it is illegal (e.g., I_FREEING when
->i_count > 0)
- Provide accessors for ->i_state, converts all filesystems using
coccinelle and manual conversions (btrfs, ceph, smb, f2fs, gfs2,
overlayfs, nilfs2, xfs), and makes plain ->i_state access fail to
compile
- Rework I_NEW handling to operate without fences, simplifying the
code after the accessor infrastructure is in place
Cleanups:
- Move wait_on_inode() from writeback.h to fs.h
- Spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb
for clarity
- Cosmetic fixes to LRU handling
- Push list presence check into inode_io_list_del()
- Touch up predicts in __d_lookup_rcu()
- ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage
- Assert on ->i_count in iput_final()
- Assert ->i_lock held in __iget()
Fixes:
- Add missing fences to I_NEW handling"
* tag 'vfs-6.19-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (22 commits)
dcache: touch up predicts in __d_lookup_rcu()
fs: push list presence check into inode_io_list_del()
fs: cosmetic fixes to lru handling
fs: rework I_NEW handling to operate without fences
fs: make plain ->i_state access fail to compile
xfs: use the new ->i_state accessors
nilfs2: use the new ->i_state accessors
overlayfs: use the new ->i_state accessors
gfs2: use the new ->i_state accessors
f2fs: use the new ->i_state accessors
smb: use the new ->i_state accessors
ceph: use the new ->i_state accessors
btrfs: use the new ->i_state accessors
Manual conversion to use ->i_state accessors of all places not covered by coccinelle
Coccinelle-based conversion to use ->i_state accessors
fs: provide accessors for ->i_state
fs: spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb
fs: move wait_on_inode() from writeback.h to fs.h
fs: add missing fences to I_NEW handling
ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage
...
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Merge tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Features:
- Cheaper MAY_EXEC handling for path lookup. This elides MAY_WRITE
permission checks during path lookup and adds the
IOP_FASTPERM_MAY_EXEC flag so filesystems like btrfs can avoid
expensive permission work.
- Hide dentry_cache behind runtime const machinery.
- Add German Maglione as virtiofs co-maintainer.
Cleanups:
- Tidy up and inline step_into() and walk_component() for improved
code generation.
- Re-enable IOCB_NOWAIT writes to files. This refactors file
timestamp update logic, fixing a layering bypass in btrfs when
updating timestamps on device files and improving FMODE_NOCMTIME
handling in VFS now that nfsd started using it.
- Path lookup optimizations extracting slowpaths into dedicated
routines and adding branch prediction hints for mntput_no_expire(),
fd_install(), lookup_slow(), and various other hot paths.
- Enable clang's -fms-extensions flag, requiring a JFS rename to
avoid conflicts.
- Remove spurious exports in fs/file_attr.c.
- Stop duplicating union pipe_index declaration. This depends on the
shared kbuild branch that brings in -fms-extensions support which
is merged into this branch.
- Use MD5 library instead of crypto_shash in ecryptfs.
- Use largest_zero_folio() in iomap_dio_zero().
- Replace simple_strtol/strtoul with kstrtoint/kstrtouint in init and
initrd code.
- Various typo fixes.
Fixes:
- Fix emergency sync for btrfs. Btrfs requires an explicit sync_fs()
call with wait == 1 to commit super blocks. The emergency sync path
never passed this, leaving btrfs data uncommitted during emergency
sync.
- Use local kmap in watch_queue's post_one_notification().
- Add hint prints in sb_set_blocksize() for LBS dependency on THP"
* tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
MAINTAINERS: add German Maglione as virtiofs co-maintainer
fs: inline step_into() and walk_component()
fs: tidy up step_into() & friends before inlining
orangefs: use inode_update_timestamps directly
btrfs: fix the comment on btrfs_update_time
btrfs: use vfs_utimes to update file timestamps
fs: export vfs_utimes
fs: lift the FMODE_NOCMTIME check into file_update_time_flags
fs: refactor file timestamp update logic
include/linux/fs.h: trivial fix: regualr -> regular
fs/splice.c: trivial fix: pipes -> pipe's
fs: mark lookup_slow() as noinline
fs: add predicts based on nd->depth
fs: move mntput_no_expire() slowpath into a dedicated routine
fs: remove spurious exports in fs/file_attr.c
watch_queue: Use local kmap in post_one_notification()
fs: touch up predicts in path lookup
fs: move fd_install() slowpath into a dedicated routine and provide commentary
fs: hide dentry_cache behind runtime const machinery
fs: touch predicts in do_dentry_open()
...
FMODE_NOCMTIME used to be just a hack for the legacy XFS handle-based
"invisible I/O", but commit e5e9b24ab8 ("nfsd: freeze c/mtime updates
with outstanding WRITE_ATTRS delegation") started using it from
generic callers.
I'm not sure other file systems are actually read for this in general,
so the above commit should get a closer look, but for it to make any
sense, file_update_time needs to respect the flag.
Lift the check from file_modified_flags to file_update_time so that
users of file_update_time inherit the behavior and so that all the
checks are done in one place.
Fixes: e5e9b24ab8 ("nfsd: freeze c/mtime updates with outstanding WRITE_ATTRS delegation")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20251120064859.2911749-3-hch@lst.de
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Currently the two high-level APIs use two helper functions to implement
almost all of the logic. Refactor the two helpers and the common logic
into a new file_update_time_flags routine that gets the iocb flags or
0 in case of file_update_time passed so that the entire logic is
contained in a single function and can be easily understood and modified.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20251120064859.2911749-2-hch@lst.de
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
For consistency with sb routines.
ext4 is the only consumer outside of evict(). Damage-controlling it is
outside of the scope of this cleanup.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251103230911.516866-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
1. inode_bit_waitqueue() was somehow placed between __inode_add_lru() and
inode_add_lru(). move it up
2. assert ->i_lock is held in __inode_add_lru instead of just claiming it is
needed
3. s/__inode_add_lru/__inode_lru_list_add/ for consistency with itself
(inode_lru_list_del()) and similar routines for sb and io list
management
4. push list presence check into inode_lru_list_del(), just like sb and
io list
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251029131428.654761-2-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
In the inode hash code grab the state while ->i_lock is held. If found
to be set, synchronize the sleep once more with the lock held.
In the real world the flag is not set most of the time.
Apart from being simpler to reason about, it comes with a minor speed up
as now clearing the flag does not require the smp_mb() fence.
While here rename wait_on_inode() to wait_on_new_inode() to line it up
with __wait_on_freeing_inode().
Christian Brauner <brauner@kernel.org> says:
As per the discussion in [1] I folded in the diff sent in [2].
Link: https://lore.kernel.org/69238e4d.a70a0220.d98e3.006e.GAE@google.com [1]
Link: https://lore.kernel.org/c2kpawomkbvtahjm7y5mposbhckb7wxthi3iqy5yr22ggpucrm@ufvxwy233qxo [2]
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251010221737.1403539-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Suppose there are 2 CPUs racing inode hash lookup func (say ilookup5())
and unlock_new_inode().
In principle the latter can clear the I_NEW flag before prior stores
into the inode were made visible.
The former can in turn observe I_NEW is cleared and proceed to use the
inode, while possibly reading from not-yet-published areas.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Notably make sure the count is 0 after the return from ->drop_inode(),
provided we are going to drop.
Inspired by suspicious games played by f2fs.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Merge tag 'vfs-6.18-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs inode updates from Christian Brauner:
"This contains a series I originally wrote and that Eric brought over
the finish line. It moves out the i_crypt_info and i_verity_info
pointers out of 'struct inode' and into the fs-specific part of the
inode.
So now the few filesytems that actually make use of this pay the price
in their own private inode storage instead of forcing it upon every
user of struct inode.
The pointer for the crypt and verity info is simply found by storing
an offset to its address in struct fsverity_operations and struct
fscrypt_operations. This shrinks struct inode by 16 bytes.
I hope to move a lot more out of it in the future so that struct inode
becomes really just about very core stuff that we need, much like
struct dentry and struct file, instead of the dumping ground it has
become over the years.
On top of this are a various changes associated with the ongoing inode
lifetime handling rework that multiple people are pushing forward:
- Stop accessing inode->i_count directly in f2fs and gfs2. They
simply should use the __iget() and iput() helpers
- Make the i_state flags an enum
- Rework the iput() logic
Currently, if we are the last iput, and we have the I_DIRTY_TIME
bit set, we will grab a reference on the inode again and then mark
it dirty and then redo the put. This is to make sure we delay the
time update for as long as possible
We can rework this logic to simply dec i_count if it is not 1, and
if it is do the time update while still holding the i_count
reference
Then we can replace the atomic_dec_and_lock with locking the
->i_lock and doing atomic_dec_and_test, since we did the
atomic_add_unless above
- Add an icount_read() helper and convert everyone that accesses
inode->i_count directly for this purpose to use the helper
- Expand dump_inode() to dump more information about an inode helping
in debugging
- Add some might_sleep() annotations to iput() and associated
helpers"
* tag 'vfs-6.18-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: add might_sleep() annotation to iput() and more
fs: expand dump_inode()
inode: fix whitespace issues
fs: add an icount_read helper
fs: rework iput logic
fs: make the i_state flags an enum
fs: stop accessing ->i_count directly in f2fs and gfs2
fsverity: check IS_VERITY() in fsverity_cleanup_inode()
fs: remove inode::i_verity_info
btrfs: move verity info pointer to fs-specific part of inode
f2fs: move verity info pointer to fs-specific part of inode
ext4: move verity info pointer to fs-specific part of inode
fsverity: add support for info in fs-specific part of inode
fs: remove inode::i_crypt_info
ceph: move crypt info pointer to fs-specific part of inode
ubifs: move crypt info pointer to fs-specific part of inode
f2fs: move crypt info pointer to fs-specific part of inode
ext4: move crypt info pointer to fs-specific part of inode
fscrypt: add support for info in fs-specific part of inode
fscrypt: replace raw loads of info pointer with helper function
When iput() drops the reference counter to zero, it may sleep via
inode_wait_for_writeback(). This happens rarely because it's usually
the dcache which evicts inodes, but really iput() should only ever be
called in contexts where sleeping is allowed. This annotation allows
finding buggy callers.
Additionally, this patch annotates a few low-level functions that can
call iput() conditionally.
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/20250917153632.2228828-1-max.kellermann@ionos.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
generic_delete_inode() is rather misleading for what the routine is
doing. inode_just_drop() should be much clearer.
The new naming is inconsistent with generic_drop_inode(), so rename that
one as well with inode_ as the suffix.
No functional changes.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This adds fs name and few fields from struct inode: i_mode, i_opflags,
i_flags, i_state and i_count.
All values printed raw, no attempt to pretty-print anything.
Compile tested on i386 and runtime tested on amd64.
Sample output:
[ 23.121281] VFS_WARN_ON_INODE("crap") encountered for inode ffff9a1a83ce3660
fs pipefs mode 10600 opflags 0x4 flags 0x0 state 0x38 count 0
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Similar to may_open().
No functional changes.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Currently, if we are the last iput, and we have the I_DIRTY_TIME bit
set, we will grab a reference on the inode again and then mark it dirty
and then redo the put. This is to make sure we delay the time update
for as long as possible.
We can rework this logic to simply dec i_count if it is not 1, and if it
is do the time update while still holding the i_count reference.
Then we can replace the atomic_dec_and_lock with locking the ->i_lock
and doing atomic_dec_and_test, since we did the atomic_add_unless above.
Co-developed-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/be208b89bdb650202e712ce2bcfc407ac7044c7a.1756222464.git.josef@toxicpanda.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Commit 8b17e54096 ("vfs: add initial support for CONFIG_DEBUG_VFS") added
dump_inode(), but dump_inode() currently reports only raw pointer address.
Comment says that adding a proper inode dumping routine is a TODO.
However, syzkaller concurrently tests multiple filesystems, and several
filesystems started calling dump_inode() due to hitting VFS_BUG_ON_INODE()
added by commit af153bb63a ("vfs: catch invalid modes in may_open()")
before a proper inode dumping routine is implemented.
Show filesystem name at dump_inode() so that we can find which filesystem
has passed an invalid mode to may_open() from syzkaller's crash reports.
Link: https://syzkaller.appspot.com/bug?extid=895c23f6917da440ed0d
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/ceaf4021-65cc-422e-9d0e-6afa18dd8276@I-love.SAKURA.ne.jp
Signed-off-by: Christian Brauner <brauner@kernel.org>
file_remove_privs_flags is only used inside of inode.c, mark it static.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250724074854.3316911-1-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
evict_inodes() uses list_for_each_entry_safe() to iterate sb->s_inodes
list. However, since we use i_lru list entry for our local temporary
list of inodes to destroy, the inode is guaranteed to stay in
sb->s_inodes list while we hold sb->s_inode_list_lock. So there is no
real need for safe iteration variant and we can use
list_for_each_entry() just fine.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/20250709090635.26319-2-jack@suse.cz
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
VFS has switched to i_rwsem for ten years now (9902af79c01a: parallel
lookups actual switch to rwsem), but the VFS documentation and comments
still has references to i_mutex.
Signed-off-by: Junxuan Liao <ljx@cs.wisc.edu>
Link: https://lore.kernel.org/72223729-5471-474a-af3c-f366691fba82@cs.wisc.edu
Signed-off-by: Christian Brauner <brauner@kernel.org>
As both locks are highly contended during significant inode churn,
holding the inode hash lock while waiting for the sb list lock
exacerbates the problem.
Why moving it out is safe: the inode at hand still has I_NEW set and
anyone who finds it through legitimate means waits for the bit to clear,
by which time inode_sb_list_add() is guaranteed to have finished.
This significantly drops hash lock contention for me when stating 20
separate trees in parallel, each with 1000 directories * 1000 files.
However, no speed up was observed as contention increased on the other
locks, notably dentry LRU.
Even so, removal of the lock ordering will help making this faster
later.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250320004643.1903287-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
While this may sound like a pedantic clean up, it does in fact impact
code generation -- the patched add routine is slightly smaller.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250319004635.1820589-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
The unhashed state check in __wait_on_freeing_inode() performed with
->i_lock held against remove_hash_inode() also holding the lock makes
another lock acquire in evict() completely spurious -- all potential
sleepers already dropped the lock before remove_hash_inode() acquired
it or they found the inode to be unhashed and aborted.
Note there is no trickery here: the usual cost of both sides taking
locks is still being paid, it just stops being paid twice.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250317160707.1694135-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
The function can be replaced by evict_inodes. The only difference is
that evict_inodes() skips the inodes with positive refcount without
touching ->i_lock, but they are equivalent as evict_inodes() repeats the
refcount check after having grabbed ->i_lock.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20250307144318.28120-2-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>
The former is a no-op wrapper with the same argument.
I left it in place to not lose the information who needs it -- one day
"pseudo" inodes may start differing from what alloc_inode() returns.
In the meantime no point taking a detour.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250212180459.1022983-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.
Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25c ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.
Created this by running an spatch followed by a sed command:
Spatch:
virtual patch
@
depends on !(file in "net")
disable optional_qualifier
@
identifier table_name != {
watchdog_hardlockup_sysctl,
iwcm_ctl_table,
ucma_ctl_table,
memory_allocation_profiling_sysctls,
loadpin_sysctl_table
};
@@
+ const
struct ctl_table table_name [] = { ... };
sed:
sed --in-place \
-e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
kernel/utsname_sysctl.c
Reviewed-by: Song Liu <song@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> # for kernel/trace/
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> # SCSI
Reviewed-by: Darrick J. Wong <djwong@kernel.org> # xfs
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Acked-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Sergey Senozhatsky improves zram's post-processing selection algorithm.
This leads to improved memory savings.
- Wei Yang has gone to town on the mapletree code, contributing several
series which clean up the implementation:
- "refine mas_mab_cp()"
- "Reduce the space to be cleared for maple_big_node"
- "maple_tree: simplify mas_push_node()"
- "Following cleanup after introduce mas_wr_store_type()"
- "refine storing null"
- The series "selftests/mm: hugetlb_fault_after_madv improvements" from
David Hildenbrand fixes this selftest for s390.
- The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
implements some rationaizations and cleanups in the page mapping code.
- The series "mm: optimize shadow entries removal" from Shakeel Butt
optimizes the file truncation code by speeding up the handling of shadow
entries.
- The series "Remove PageKsm()" from Matthew Wilcox completes the
migration of this flag over to being a folio-based flag.
- The series "Unify hugetlb into arch_get_unmapped_area functions" from
Oscar Salvador implements a bunch of consolidations and cleanups in the
hugetlb code.
- The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
takes away the wp-fault time practice of turning a huge zero page into
small pages. Instead we replace the whole thing with a THP. More
consistent cleaner and potentiall saves a large number of pagefaults.
- The series "percpu: Add a test case and fix for clang" from Andy
Shevchenko enhances and fixes the kernel's built in percpu test code.
- The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
optimizes mremap() by avoiding doing things which we didn't need to do.
- The series "Improve the tmpfs large folio read performance" from
Baolin Wang teaches tmpfs to copy data into userspace at the folio size
rather than as individual pages. A 20% speedup was observed.
- The series "mm/damon/vaddr: Fix issue in
damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON splitting.
- The series "memcg-v1: fully deprecate charge moving" from Shakeel Butt
removes the long-deprecated memcgv2 charge moving feature.
- The series "fix error handling in mmap_region() and refactor" from
Lorenzo Stoakes cleanup up some of the mmap() error handling and
addresses some potential performance issues.
- The series "x86/module: use large ROX pages for text allocations" from
Mike Rapoport teaches x86 to use large pages for read-only-execute
module text.
- The series "page allocation tag compression" from Suren Baghdasaryan
is followon maintenance work for the new page allocation profiling
feature.
- The series "page->index removals in mm" from Matthew Wilcox remove
most references to page->index in mm/. A slow march towards shrinking
struct page.
- The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
interface tests" from Andrew Paniakin performs maintenance work for
DAMON's self testing code.
- The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
improves zswap's batching of compression and decompression. It is a
step along the way towards using Intel IAA hardware acceleration for
this zswap operation.
- The series "kasan: migrate the last module test to kunit" from
Sabyrzhan Tasbolatov completes the migration of the KASAN built-in tests
over to the KUnit framework.
- The series "implement lightweight guard pages" from Lorenzo Stoakes
permits userapace to place fault-generating guard pages within a single
VMA, rather than requiring that multiple VMAs be created for this.
Improved efficiencies for userspace memory allocators are expected.
- The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
tracepoints to provide increased visibility into memcg stats flushing
activity.
- The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
fixes a zram buglet which potentially affected performance.
- The series "mm: add more kernel parameters to control mTHP" from
Maíra Canal enhances our ability to control/configuremultisize THP from
the kernel boot command line.
- The series "kasan: few improvements on kunit tests" from Sabyrzhan
Tasbolatov has a couple of fixups for the KASAN KUnit tests.
- The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
from Kairui Song optimizes list_lru memory utilization when lockdep is
enabled.
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Merge tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- The series "zram: optimal post-processing target selection" from
Sergey Senozhatsky improves zram's post-processing selection
algorithm. This leads to improved memory savings.
- Wei Yang has gone to town on the mapletree code, contributing several
series which clean up the implementation:
- "refine mas_mab_cp()"
- "Reduce the space to be cleared for maple_big_node"
- "maple_tree: simplify mas_push_node()"
- "Following cleanup after introduce mas_wr_store_type()"
- "refine storing null"
- The series "selftests/mm: hugetlb_fault_after_madv improvements" from
David Hildenbrand fixes this selftest for s390.
- The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
implements some rationaizations and cleanups in the page mapping
code.
- The series "mm: optimize shadow entries removal" from Shakeel Butt
optimizes the file truncation code by speeding up the handling of
shadow entries.
- The series "Remove PageKsm()" from Matthew Wilcox completes the
migration of this flag over to being a folio-based flag.
- The series "Unify hugetlb into arch_get_unmapped_area functions" from
Oscar Salvador implements a bunch of consolidations and cleanups in
the hugetlb code.
- The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
takes away the wp-fault time practice of turning a huge zero page
into small pages. Instead we replace the whole thing with a THP. More
consistent cleaner and potentiall saves a large number of pagefaults.
- The series "percpu: Add a test case and fix for clang" from Andy
Shevchenko enhances and fixes the kernel's built in percpu test code.
- The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
optimizes mremap() by avoiding doing things which we didn't need to
do.
- The series "Improve the tmpfs large folio read performance" from
Baolin Wang teaches tmpfs to copy data into userspace at the folio
size rather than as individual pages. A 20% speedup was observed.
- The series "mm/damon/vaddr: Fix issue in
damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON
splitting.
- The series "memcg-v1: fully deprecate charge moving" from Shakeel
Butt removes the long-deprecated memcgv2 charge moving feature.
- The series "fix error handling in mmap_region() and refactor" from
Lorenzo Stoakes cleanup up some of the mmap() error handling and
addresses some potential performance issues.
- The series "x86/module: use large ROX pages for text allocations"
from Mike Rapoport teaches x86 to use large pages for
read-only-execute module text.
- The series "page allocation tag compression" from Suren Baghdasaryan
is followon maintenance work for the new page allocation profiling
feature.
- The series "page->index removals in mm" from Matthew Wilcox remove
most references to page->index in mm/. A slow march towards shrinking
struct page.
- The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
interface tests" from Andrew Paniakin performs maintenance work for
DAMON's self testing code.
- The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
improves zswap's batching of compression and decompression. It is a
step along the way towards using Intel IAA hardware acceleration for
this zswap operation.
- The series "kasan: migrate the last module test to kunit" from
Sabyrzhan Tasbolatov completes the migration of the KASAN built-in
tests over to the KUnit framework.
- The series "implement lightweight guard pages" from Lorenzo Stoakes
permits userapace to place fault-generating guard pages within a
single VMA, rather than requiring that multiple VMAs be created for
this. Improved efficiencies for userspace memory allocators are
expected.
- The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
tracepoints to provide increased visibility into memcg stats flushing
activity.
- The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
fixes a zram buglet which potentially affected performance.
- The series "mm: add more kernel parameters to control mTHP" from
Maíra Canal enhances our ability to control/configuremultisize THP
from the kernel boot command line.
- The series "kasan: few improvements on kunit tests" from Sabyrzhan
Tasbolatov has a couple of fixups for the KASAN KUnit tests.
- The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
from Kairui Song optimizes list_lru memory utilization when lockdep
is enabled.
* tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits)
cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
mm/kfence: add a new kunit test test_use_after_free_read_nofault()
zram: fix NULL pointer in comp_algorithm_show()
memcg/hugetlb: add hugeTLB counters to memcg
vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event
mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
zram: ZRAM_DEF_COMP should depend on ZRAM
MAINTAINERS/MEMORY MANAGEMENT: add document files for mm
Docs/mm/damon: recommend academic papers to read and/or cite
mm: define general function pXd_init()
kmemleak: iommu/iova: fix transient kmemleak false positive
mm/list_lru: simplify the list_lru walk callback function
mm/list_lru: split the lock to per-cgroup scope
mm/list_lru: simplify reparenting and initial allocation
mm/list_lru: code clean up for reparenting
mm/list_lru: don't export list_lru_add
mm/list_lru: don't pass unnecessary key parameters
kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller
kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW
kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols
...
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Merge tag 'vfs-6.13.misc' of 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 681ce86235 ("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
4a4be1ad3a ("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
...
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Merge tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs multigrain timestamps from Christian Brauner:
"This is another try at implementing multigrain timestamps. This time
with significant help from the timekeeping maintainers to reduce the
performance impact.
Thomas provided a base branch that contains the required timekeeping
interfaces for the VFS. It serves as the base for the multi-grain
timestamp work:
- Multigrain timestamps allow the kernel to use fine-grained
timestamps when an inode's attributes is being actively observed
via ->getattr(). With this support, it's possible for a file to get
a fine-grained timestamp, and another modified after it to get a
coarse-grained stamp that is earlier than the fine-grained time. If
this happens then the files can appear to have been modified in
reverse order, which breaks VFS ordering guarantees.
To prevent this, a floor value is maintained for multigrain
timestamps. Whenever a fine-grained timestamp is handed out, record
it, and when later coarse-grained stamps are handed out, ensure
they are not earlier than that value. If the coarse-grained
timestamp is earlier than the fine-grained floor, return the floor
value instead.
The timekeeper changes add a static singleton atomic64_t into
timekeeper.c that is used to keep track of the latest fine-grained
time ever handed out. This is tracked as a monotonic ktime_t value
to ensure that it isn't affected by clock jumps. Because it is
updated at different times than the rest of the timekeeper object,
the floor value is managed independently of the timekeeper via a
cmpxchg() operation, and sits on its own cacheline.
Two new public timekeeper interfaces are added:
(1) ktime_get_coarse_real_ts64_mg() fills a timespec64 with the
later of the coarse-grained clock and the floor time
(2) ktime_get_real_ts64_mg() gets the fine-grained clock value,
and tries to swap it into the floor. A timespec64 is filled
with the result.
- The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around
1 per jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting
via NFSv3, which relies on timestamps to validate caches. A lot of
changes can happen in a jiffy, so timestamps aren't sufficient to
help the client decide when to invalidate the cache. Even with
NFSv4, a lot of exported filesystems don't properly support a
change attribute and are subject to the same problems with
timestamp granularity. Other applications have similar issues with
timestamps (e.g backup applications).
If we were to always use fine-grained timestamps, that would
improve the situation, but that becomes rather expensive, as the
underlying filesystem would have to log a lot more metadata
updates.
This adds a way to only use fine-grained timestamps when they are
being actively queried. Use the (unused) top bit in
inode->i_ctime_nsec as a flag that indicates whether the current
timestamps have been queried via stat() or the like. When it's set,
we allow the kernel to use a fine-grained timestamp iff it's
necessary to make the ctime show a different value.
This solves the problem of being able to distinguish the timestamp
between updates, but introduces a new problem: it's now possible
for a file being changed to get a fine-grained timestamp. A file
that is altered just a bit later can then get a coarse-grained one
that appears older than the earlier fine-grained time. This
violates timestamp ordering guarantees.
This is where the earlier mentioned timkeeping interfaces help. A
global monotonic atomic64_t value is kept that acts as a timestamp
floor. When we go to stamp a file, we first get the latter of the
current floor value and the current coarse-grained time. If the
inode ctime hasn't been queried then we just attempt to stamp it
with that value.
If it has been queried, then first see whether the current coarse
time is later than the existing ctime. If it is, then we accept
that value. If it isn't, then we get a fine-grained time and try to
swap that into the global floor. Whether that succeeds or fails, we
take the resulting floor time, convert it to realtime and try to
swap that into the ctime.
We take the result of the ctime swap whether it succeeds or fails,
since either is just as valid.
Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same
floor value as multigrain filesystems)"
* tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: reduce pointer chasing in is_mgtime() test
tmpfs: add support for multigrain timestamps
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
Documentation: add a new file documenting multigrain timestamps
fs: add percpu counters for significant multigrain timestamp events
fs: tracepoints around multigrain timestamp events
fs: handle delegated timestamps in setattr_copy_mgtime
timekeeping: Add percpu counter for tracking floor swap events
timekeeping: Add interfaces for handling timestamps with a floor value
fs: have setattr_copy handle multigrain timestamps appropriately
fs: add infrastructure for multigrain timestamps
The is_mgtime test checks whether the FS_MGTIME flag is set in the
fstype. To get there from the inode though, we have to dereference 3
pointers.
Add a new IOP_MGTIME flag, and have inode_init_always() set that flag
when the fstype flag is set. Then, make is_mgtime test for IOP_MGTIME
instead.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241113-mgtime-v1-1-84e256980e11@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
It literally directly follows a spin_lock() call.
This whacks an explicit barrier on x86-64.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20241113155103.4194099-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Now isolation no longer takes the list_lru global node lock, only use the
per-cgroup lock instead. And this lock is inside the list_lru_one being
walked, no longer needed to pass the lock explicitly.
Link: https://lkml.kernel.org/r/20241104175257.60853-7-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently, every list_lru has a per-node lock that protects adding,
deletion, isolation, and reparenting of all list_lru_one instances
belonging to this list_lru on this node. This lock contention is heavy
when multiple cgroups modify the same list_lru.
This lock can be split into per-cgroup scope to reduce contention.
To achieve this, we need a stable list_lru_one for every cgroup. This
commit adds a lock to each list_lru_one and introduced a helper function
lock_list_lru_of_memcg, making it possible to pin the list_lru of a memcg.
Then reworked the reparenting process.
Reparenting will switch the list_lru_one instances one by one. By locking
each instance and marking it dead using the nr_items counter, reparenting
ensures that all items in the corresponding cgroup (on-list or not,
because items have a stable cgroup, see below) will see the list_lru_one
switch synchronously.
Objcg reparent is also moved after list_lru reparent so items will have a
stable mem cgroup until all list_lru_one instances are drained.
The only caller that doesn't work the *_obj interfaces are direct calls to
list_lru_{add,del}. But it's only used by zswap and that's also based on
objcg, so it's fine.
This also changes the bahaviour of the isolation function when LRU_RETRY
or LRU_REMOVED_RETRY is returned, because now releasing the lock could
unblock reparenting and free the list_lru_one, isolation function will
have to return withoug re-lock the lru.
prepare() {
mkdir /tmp/test-fs
modprobe brd rd_nr=1 rd_size=33554432
mkfs.xfs -f /dev/ram0
mount -t xfs /dev/ram0 /tmp/test-fs
for i in $(seq 1 512); do
mkdir "/tmp/test-fs/$i"
for j in $(seq 1 10240); do
echo TEST-CONTENT > "/tmp/test-fs/$i/$j"
done &
done; wait
}
do_test() {
read_worker() {
sleep 1
tar -cv "$1" &>/dev/null
}
read_in_all() {
cd "/tmp/test-fs" && ls
for i in $(seq 1 512); do
(exec sh -c 'echo "$PPID"') > "/sys/fs/cgroup/benchmark/$i/cgroup.procs"
read_worker "$i" &
done; wait
}
for i in $(seq 1 512); do
mkdir -p "/sys/fs/cgroup/benchmark/$i"
done
echo +memory > /sys/fs/cgroup/benchmark/cgroup.subtree_control
echo 512M > /sys/fs/cgroup/benchmark/memory.max
echo 3 > /proc/sys/vm/drop_caches
time read_in_all
}
Above script simulates compression of small files in multiple cgroups
with memory pressure. Run prepare() then do_test for 6 times:
Before:
real 0m7.762s user 0m11.340s sys 3m11.224s
real 0m8.123s user 0m11.548s sys 3m2.549s
real 0m7.736s user 0m11.515s sys 3m11.171s
real 0m8.539s user 0m11.508s sys 3m7.618s
real 0m7.928s user 0m11.349s sys 3m13.063s
real 0m8.105s user 0m11.128s sys 3m14.313s
After this commit (about ~15% faster):
real 0m6.953s user 0m11.327s sys 2m42.912s
real 0m7.453s user 0m11.343s sys 2m51.942s
real 0m6.916s user 0m11.269s sys 2m43.957s
real 0m6.894s user 0m11.528s sys 2m45.346s
real 0m6.911s user 0m11.095s sys 2m43.168s
real 0m6.773s user 0m11.518s sys 2m40.774s
Link: https://lkml.kernel.org/r/20241104175257.60853-6-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Some minor corrections to the inode_insert5 and iget5_locked kernel
documentation.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Link: https://lore.kernel.org/r/20241004115151.44834-1-agruenba@redhat.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Jeff Layton <jlayton@kernel.org> says:
The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around 1
per jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide when to invalidate the cache. Even with NFSv4, a lot of
exported filesystems don't properly support a change attribute and are
subject to the same problems with timestamp granularity. Other
applications have similar issues with timestamps (e.g backup
applications).
If we were to always use fine-grained timestamps, that would improve the
situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.
What we need is a way to only use fine-grained timestamps when they are
being actively queried. Use the (unused) top bit in inode->i_ctime_nsec
as a flag that indicates whether the current timestamps have been
queried via stat() or the like. When it's set, we allow the kernel to
use a fine-grained timestamp iff it's necessary to make the ctime show
a different value.
This solves the problem of being able to distinguish the timestamp
between updates, but introduces a new problem: it's now possible for a
file being changed to get a fine-grained timestamp. A file that is
altered just a bit later can then get a coarse-grained one that appears
older than the earlier fine-grained time. This violates timestamp
ordering guarantees.
To remedy this, keep a global monotonic atomic64_t value that acts as a
timestamp floor. When we go to stamp a file, we first get the latter of
the current floor value and the current coarse-grained time. If the
inode ctime hasn't been queried then we just attempt to stamp it with
that value.
If it has been queried, then first see whether the current coarse time
is later than the existing ctime. If it is, then we accept that value.
If it isn't, then we get a fine-grained time and try to swap that into
the global floor. Whether that succeeds or fails, we take the resulting
floor time, convert it to realtime and try to swap that into the ctime.
We take the result of the ctime swap whether it succeeds or fails, since
either is just as valid.
Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same floor
value as multigrain filesystems).
* patches from https://lore.kernel.org/r/20241002-mgtime-v10-0-d1c4717f5284@kernel.org:
tmpfs: add support for multigrain timestamps
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
Documentation: add a new file documenting multigrain timestamps
fs: add percpu counters for significant multigrain timestamp events
fs: tracepoints around multigrain timestamp events
fs: handle delegated timestamps in setattr_copy_mgtime
fs: have setattr_copy handle multigrain timestamps appropriately
fs: add infrastructure for multigrain timestamps
Link: https://lore.kernel.org/r/20241002-mgtime-v10-0-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
New percpu counters for counting various stats around multigrain
timestamp events, and a new debugfs file for displaying them when
CONFIG_DEBUG_FS is enabled:
- number of attempted ctime updates
- number of successful i_ctime_nsec swaps
- number of fine-grained timestamp fetches
- number of floor value swap events
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-7-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Add some tracepoints around various multigrain timestamp events.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-6-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
An update to the inode ctime typically requires the latest clock
value possible. The exception to this rule is when there is a nfsd write
delegation and the server is proxying timestamps from the client.
When nfsd gets a CB_GETATTR response, update the timestamp value in the
inode to the values that the client is tracking. The client doesn't send
a ctime value (since that's always determined by the exported
filesystem), but it can send a mtime value. In the case where it does,
update the ctime to a value commensurate with that instead of the
current time.
If ATTR_DELEG is set, then use ia_ctime value instead of setting the
timestamp to the current time.
With the addition of delegated timestamps, the server may receive a
request to update only the atime, which doesn't involve a ctime update.
Trust the ATTR_CTIME flag in the update and only update the ctime when
it's set.
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-5-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Patch series "remove PF_MEMALLOC_NORECLAIM" v3.
This patch (of 2):
bch2_new_inode relies on PF_MEMALLOC_NORECLAIM to try to allocate a new
inode to achieve GFP_NOWAIT semantic while holding locks. If this
allocation fails it will drop locks and use GFP_NOFS allocation context.
We would like to drop PF_MEMALLOC_NORECLAIM because it is really
dangerous to use if the caller doesn't control the full call chain with
this flag set. E.g. if any of the function down the chain needed
GFP_NOFAIL request the PF_MEMALLOC_NORECLAIM would override this and
cause unexpected failure.
While this is not the case in this particular case using the scoped gfp
semantic is not really needed bacause we can easily pus the allocation
context down the chain without too much clutter.
[akpm@linux-foundation.org: fix kerneldoc warnings]
Link: https://lkml.kernel.org/r/20240926172940.167084-1-mhocko@kernel.org
Link: https://lkml.kernel.org/r/20240926172940.167084-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz> # For vfs changes
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: James Morris <jmorris@namei.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around 1
per jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide when to invalidate the cache. Even with NFSv4, a lot of
exported filesystems don't properly support a change attribute and are
subject to the same problems with timestamp granularity. Other
applications have similar issues with timestamps (e.g backup
applications).
If fine-grained timestamps were always used, that would improve the
situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.
What is needed is a way to only use fine-grained timestamps when they
are being actively queried. Use the (unused) top bit in
inode->i_ctime_nsec as a flag that indicates whether the current
timestamps have been queried via stat() or the like. When it's set,
allow the update to use a fine-grained timestamp iff it's necessary to
make the ctime show a different value.
If it has been queried, then first see whether the current coarse time
is later than the existing ctime. If it is, accept that value. If it
isn't, then get a fine-grained timestamp and attempt to stamp the inode
ctime with that value. If that races with another concurrent stamp, then
abandon the update and take the new value without retrying.
Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same floor
value as multigrain filesystems).
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-3-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
rcu_pending, btree key cache rework: this solves lock contenting in the
key cache, eliminating the biggest source of the srcu lock hold time
warnings, and drastically improving performance on some metadata heavy
workloads - on multithreaded creates we're now 3-4x faster than xfs.
We're now using an rhashtable instead of the system inode hash table;
this is another significant performance improvement on multithreaded
metadata workloads, eliminating more lock contention.
for_each_btree_key_in_subvolume_upto(): new helper for iterating over
keys within a specific subvolume, eliminating a lot of open coded
"subvolume_get_snapshot()" and also fixing another source of srcu lock
time warnings, by running each loop iteration in its own transaction (as
the existing for_each_btree_key() does).
More work on btree_trans locking asserts; we now assert that we don't
hold btree node locks when trans->locked is false, which is important
because we don't use lockdep for tracking individual btree node locks.
Some cleanups and improvements in the bset.c btree node lookup code,
from Alan.
Rework of btree node pinning, which we use in backpointers fsck. The old
hacky implementation, where the shrinker just skipped over nodes in the
pinned range, was causing OOMs; instead we now use another shrinker with
a much higher seeks number for pinned nodes.
Rebalance now uses BCH_WRITE_ONLY_SPECIFIED_DEVS; this fixes an issue
where rebalance would sometimes fall back to allocating from the full
filesystem, which is not what we want when it's trying to move data to a
specific target.
Use __GFP_ACCOUNT, GFP_RECLAIMABLE for btree node, key cache
allocations.
Idmap mounts are now supported - Hongbo.
Rename whiteouts are now supported - Hongbo.
Erasure coding can now handle devices being marked as failed, or
forcibly removed. We still need the evacuate path for erasure coding,
but it's getting very close to ready for people to start using.
Status, and when will we be taking off experimental:
----------------------------------------------------
Going by critical, user facing bugs getting found and fixed, we're
nearly there. There are a couple key items that need to be finished
before we can take off the experimental label:
- The end-user experience is still pretty painful when the root
filesystem needs a fsck; we need some form of limited self healing so
that necessary repair gets run automatically. Errors (by type) are
recorded in the superblock, so what we need to do next is convert
remaining inconsistent() errors to fsck() errors (so that all runtime
inconsistencies are logged in the superblock), and we need to go
through the list of fsck errors and classify them by which fsck passes
are needed to repair them.
- We need comprehensive torture testing for all our repair paths, to
shake out remaining bugs there. Thomas has been working on the tooling
for this, so this is coming soonish.
Slightly less critical items:
- We need to improve the end-user experience for degraded mounts: right
now, a degraded root filesystem means dropping to an initramfs shell
or somehow inputting mount options manually (we don't want to allow
degraded mounts without some form of user input, except on unattended
servers) - we need the mount helper to prompt the user to allow
mounting degraded, and make sure this works with systemd.
- Scalabiity: we have users running 100TB+ filesystems, and that's
effectively the limit right now due to fsck times. We have some
reworks in the pipeline to address this, we're aiming to make petabyte
sized filesystems practical.
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Merge tag 'bcachefs-2024-09-21' of git://evilpiepirate.org/bcachefs
Pull bcachefs updates from Kent Overstreet:
- rcu_pending, btree key cache rework: this solves lock contenting in
the key cache, eliminating the biggest source of the srcu lock hold
time warnings, and drastically improving performance on some metadata
heavy workloads - on multithreaded creates we're now 3-4x faster than
xfs.
- We're now using an rhashtable instead of the system inode hash table;
this is another significant performance improvement on multithreaded
metadata workloads, eliminating more lock contention.
- for_each_btree_key_in_subvolume_upto(): new helper for iterating over
keys within a specific subvolume, eliminating a lot of open coded
"subvolume_get_snapshot()" and also fixing another source of srcu
lock time warnings, by running each loop iteration in its own
transaction (as the existing for_each_btree_key() does).
- More work on btree_trans locking asserts; we now assert that we don't
hold btree node locks when trans->locked is false, which is important
because we don't use lockdep for tracking individual btree node
locks.
- Some cleanups and improvements in the bset.c btree node lookup code,
from Alan.
- Rework of btree node pinning, which we use in backpointers fsck. The
old hacky implementation, where the shrinker just skipped over nodes
in the pinned range, was causing OOMs; instead we now use another
shrinker with a much higher seeks number for pinned nodes.
- Rebalance now uses BCH_WRITE_ONLY_SPECIFIED_DEVS; this fixes an issue
where rebalance would sometimes fall back to allocating from the full
filesystem, which is not what we want when it's trying to move data
to a specific target.
- Use __GFP_ACCOUNT, GFP_RECLAIMABLE for btree node, key cache
allocations.
- Idmap mounts are now supported (Hongbo Li)
- Rename whiteouts are now supported (Hongbo Li)
- Erasure coding can now handle devices being marked as failed, or
forcibly removed. We still need the evacuate path for erasure coding,
but it's getting very close to ready for people to start using.
* tag 'bcachefs-2024-09-21' of git://evilpiepirate.org/bcachefs: (99 commits)
bcachefs: return err ptr instead of null in read sb clean
bcachefs: Remove duplicated include in backpointers.c
bcachefs: Don't drop devices with stripe pointers
bcachefs: bch2_ec_stripe_head_get() now checks for change in rw devices
bcachefs: bch_fs.rw_devs_change_count
bcachefs: bch2_dev_remove_stripes()
bcachefs: bch2_trigger_ptr() calculates sectors even when no device
bcachefs: improve error messages in bch2_ec_read_extent()
bcachefs: improve error message on too few devices for ec
bcachefs: improve bch2_new_stripe_to_text()
bcachefs: ec_stripe_head.nr_created
bcachefs: bch_stripe.disk_label
bcachefs: stripe_to_mem()
bcachefs: EIO errcode cleanup
bcachefs: Rework btree node pinning
bcachefs: split up btree cache counters for live, freeable
bcachefs: btree cache counters should be size_t
bcachefs: Don't count "skipped access bit" as touched in btree cache scan
bcachefs: Failed devices no longer require mounting in degraded mode
bcachefs: bch2_dev_rcu_noerror()
...
bcachefs is switching to an rhashtable for vfs inodes instead of the
standard inode.c hashtable, so we need this exported, or - a static
inline makes more sense for a single atomic_inc().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Mateusz Guzik
Linus Torvalds
Christoph Hellwig
Max Kellermann
Christian Brauner
Josef Bacik
Tetsuo Handa
Jan Kara
Junxuan Liao
Joel Granados
Jeff Layton
Kairui Song
Andrew Kreimer
Andreas Gruenbacher
Michal Hocko
Kent Overstreet
Li Zhijian