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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs inode / dentry updates from Christian Brauner:
"This contains smaller performance improvements to inodes and dentries:
inode:
- Add rcu based inode lookup variants.
They avoid one inode hash lock acquire in the common case thereby
significantly reducing contention. We already support RCU-based
operations but didn't take advantage of them during inode
insertion.
Callers of iget_locked() get the improvement without any code
changes. Callers that need a custom callback can switch to
iget5_locked_rcu() as e.g., did btrfs.
With 20 threads each walking a dedicated 1000 dirs * 1000 files
directory tree to stat(2) on a 32 core + 24GB ram vm:
before: 3.54s user 892.30s system 1966% cpu 45.549 total
after: 3.28s user 738.66s system 1955% cpu 37.932 total (-16.7%)
Long-term we should pick up the effort to introduce more
fine-grained locking and possibly improve on the currently used
hash implementation.
- Start zeroing i_state in inode_init_always() instead of doing it in
individual filesystems.
This allows us to remove an unneeded lock acquire in new_inode()
and not burden individual filesystems with this.
dcache:
- Move d_lockref out of the area used by RCU lookup to avoid
cacheline ping poing because the embedded name is sharing a
cacheline with d_lockref.
- Fix dentry size on 32bit with CONFIG_SMP=y so it does actually end
up with 128 bytes in total"
* tag 'vfs-6.11.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: fix dentry size
vfs: move d_lockref out of the area used by RCU lookup
bcachefs: remove now spurious i_state initialization
xfs: remove now spurious i_state initialization in xfs_inode_alloc
vfs: partially sanitize i_state zeroing on inode creation
xfs: preserve i_state around inode_init_always in xfs_reinit_inode
btrfs: use iget5_locked_rcu
vfs: add rcu-based find_inode variants for iget ops
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On CONFIG_SMP=y and on 32bit we need to decrease DNAME_INLINE_LEN to 36
btyes to end up with 128 bytes in total.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Links: https://lore.kernel.org/r/CAHk-=whtoqTSCcAvV-X-KPqoDWxS4vxmWpuKLB+Vv8=FtUd5vA@mail.gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Stock kernel scales worse than FreeBSD when doing a 20-way stat(2) on
the same tmpfs-backed file.
According to perf top:
38.09% lockref_put_return
26.08% lockref_get_not_dead
25.60% __d_lookup_rcu
0.89% clear_bhb_loop
__d_lookup_rcu is participating in cacheline ping pong due to the
embedded name sharing a cacheline with lockref.
Moving it out resolves the problem:
41.50% lockref_put_return
41.03% lockref_get_not_dead
1.54% clear_bhb_loop
benchmark (will-it-scale, Sapphire Rapids, tmpfs, ops/s):
FreeBSD:7219334
before: 5038006
after: 7842883 (+55%)
One minor remark: the 'after' result is unstable, fluctuating in the
range ~7.8 mln to ~9 mln during different runs.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240613001215.648829-3-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The routine is used by procfs through dir_emit_dots.
The combined RCU and lock fallback implementation is too big for an
inline. Given that the routine takes a dentry argument fs/dcache.c seems
like the place to put it in.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240627161152.802567-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Misc features, cleanups, and fixes for vfs and individual filesystems.
Features:
- Support idmapped mounts for hugetlbfs.
- Add RWF_NOAPPEND flag for pwritev2(). This allows us to fix a bug
where the passed offset is ignored if the file is O_APPEND. The new
flag allows a caller to enforce that the offset is honored to
conform to posix even if the file was opened in append mode.
- Move i_mmap_rwsem in struct address_space to avoid false sharing
between i_mmap and i_mmap_rwsem.
- Convert efs, qnx4, and coda to use the new mount api.
- Add a generic is_dot_dotdot() helper that's used by various
filesystems and the VFS code instead of open-coding it multiple
times.
- Recently we've added stable offsets which allows stable ordering
when iterating directories exported through NFS on e.g., tmpfs
filesystems. Originally an xarray was used for the offset map but
that caused slab fragmentation issues over time. This switches the
offset map to the maple tree which has a dense mode that handles
this scenario a lot better. Includes tests.
- Finally merge the case-insensitive improvement series Gabriel has
been working on for a long time. This cleanly propagates case
insensitive operations through ->s_d_op which in turn allows us to
remove the quite ugly generic_set_encrypted_ci_d_ops() operations.
It also improves performance by trying a case-sensitive comparison
first and then fallback to case-insensitive lookup if that fails.
This also fixes a bug where overlayfs would be able to be mounted
over a case insensitive directory which would lead to all sort of
odd behaviors.
Cleanups:
- Make file_dentry() a simple accessor now that ->d_real() is
simplified because of the backing file work we did the last two
cycles.
- Use the dedicated file_mnt_idmap helper in ntfs3.
- Use smp_load_acquire/store_release() in the i_size_read/write
helpers and thus remove the hack to handle i_size reads in the
filemap code.
- The SLAB_MEM_SPREAD is a nop now. Remove it from various places in
fs/
- It's no longer necessary to perform a second built-in initramfs
unpack call because we retain the contents of the previous
extraction. Remove it.
- Now that we have removed various allocators kfree_rcu() always
works with kmem caches and kmalloc(). So simplify various places
that only use an rcu callback in order to handle the kmem cache
case.
- Convert the pipe code to use a lockdep comparison function instead
of open-coding the nesting making lockdep validation easier.
- Move code into fs-writeback.c that was located in a header but can
be made static as it's only used in that one file.
- Rewrite the alignment checking iterators for iovec and bvec to be
easier to read, and also significantly more compact in terms of
generated code. This saves 270 bytes of text on x86-64 (with
clang-18) and 224 bytes on arm64 (with gcc-13). In profiles it also
saves a bit of time for the same workload.
- Switch various places to use KMEM_CACHE instead of
kmem_cache_create().
- Use inode_set_ctime_to_ts() in inode_set_ctime_current()
- Use kzalloc() in name_to_handle_at() to avoid kernel infoleak.
- Various smaller cleanups for eventfds.
Fixes:
- Fix various comments and typos, and unneeded initializations.
- Fix stack allocation hack for clang in the select code.
- Improve dump_mapping() debug code on a best-effort basis.
- Fix build errors in various selftests.
- Avoid wrap-around instrumentation in various places.
- Don't allow user namespaces without an idmapping to be used for
idmapped mounts.
- Fix sysv sb_read() call.
- Fix fallback implementation of the get_name() export operation"
* tag 'vfs-6.9.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (70 commits)
hugetlbfs: support idmapped mounts
qnx4: convert qnx4 to use the new mount api
fs: use inode_set_ctime_to_ts to set inode ctime to current time
libfs: Drop generic_set_encrypted_ci_d_ops
ubifs: Configure dentry operations at dentry-creation time
f2fs: Configure dentry operations at dentry-creation time
ext4: Configure dentry operations at dentry-creation time
libfs: Add helper to choose dentry operations at mount-time
libfs: Merge encrypted_ci_dentry_ops and ci_dentry_ops
fscrypt: Drop d_revalidate once the key is added
fscrypt: Drop d_revalidate for valid dentries during lookup
fscrypt: Factor out a helper to configure the lookup dentry
ovl: Always reject mounting over case-insensitive directories
libfs: Attempt exact-match comparison first during casefolded lookup
efs: remove SLAB_MEM_SPREAD flag usage
jfs: remove SLAB_MEM_SPREAD flag usage
minix: remove SLAB_MEM_SPREAD flag usage
openpromfs: remove SLAB_MEM_SPREAD flag usage
proc: remove SLAB_MEM_SPREAD flag usage
qnx6: remove SLAB_MEM_SPREAD flag usage
...
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This reverts commit 57851607326a2beef21e67f83f4f53a90df8445a.
Unfortunately, while we only call that thing once, the callback
*can* be called more than once for the same dentry - all it
takes is rename_lock being touched while we are in d_walk().
For now let's revert it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The only remaining user of ->d_real() method is d_real_inode(), which
passed NULL inode argument to get the real data dentry.
There are no longer any users that call ->d_real() with a non-NULL
inode argument for getting a detry from a specific underlying layer.
Remove the inode argument of the method and replace it with an integer
'type' argument, to allow callers to request the real metadata dentry
instead of the real data dentry.
All the current users of d_real_inode() (e.g. uprobe) continue to get
the real data inode. Caller that need to get the real metadata inode
(e.g. IMA/EVM) can use d_inode(d_real(dentry, D_REAL_METADATA)).
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20240202110132.1584111-3-amir73il@gmail.com
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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dget_dlock() requires dentry->d_lock to be held when called, yet
contains a NULL check for dentry.
An audit of all calls to dget_dlock() shows that it is never called
with a NULL pointer (as spin_lock()/spin_unlock() would crash in these
cases):
$ git grep -W '\<dget_dlock\>'
arch/powerpc/platforms/cell/spufs/inode.c- spin_lock(&dentry->d_lock);
arch/powerpc/platforms/cell/spufs/inode.c- if (simple_positive(dentry)) {
arch/powerpc/platforms/cell/spufs/inode.c: dget_dlock(dentry);
fs/autofs/expire.c- spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
fs/autofs/expire.c- if (simple_positive(child)) {
fs/autofs/expire.c: dget_dlock(child);
fs/autofs/root.c: dget_dlock(active);
fs/autofs/root.c- spin_unlock(&active->d_lock);
fs/autofs/root.c: dget_dlock(expiring);
fs/autofs/root.c- spin_unlock(&expiring->d_lock);
fs/ceph/dir.c- if (!spin_trylock(&dentry->d_lock))
fs/ceph/dir.c- continue;
[...]
fs/ceph/dir.c: dget_dlock(dentry);
fs/ceph/mds_client.c- spin_lock(&alias->d_lock);
[...]
fs/ceph/mds_client.c: dn = dget_dlock(alias);
fs/configfs/inode.c- spin_lock(&dentry->d_lock);
fs/configfs/inode.c- if (simple_positive(dentry)) {
fs/configfs/inode.c: dget_dlock(dentry);
fs/libfs.c: found = dget_dlock(d);
fs/libfs.c- spin_unlock(&d->d_lock);
fs/libfs.c: found = dget_dlock(child);
fs/libfs.c- spin_unlock(&child->d_lock);
fs/libfs.c: child = dget_dlock(d);
fs/libfs.c- spin_unlock(&d->d_lock);
fs/ocfs2/dcache.c: dget_dlock(dentry);
fs/ocfs2/dcache.c- spin_unlock(&dentry->d_lock);
include/linux/dcache.h:static inline struct dentry *dget_dlock(struct dentry *dentry)
After taking out the NULL check, dget_dlock() becomes almost identical
to __dget_dlock(); the only difference is that dget_dlock() returns the
dentry that was passed in. These are static inline helpers, so we can
rely on the compiler to discard unused return values. We can therefore
also remove __dget_dlock() and replace calls to it by dget_dlock().
Also fix up and improve the kerneldoc comments while we're at it.
Al Viro pointed out that we can also clean up some of the callers to
make use of the returned value and provided a bit more info for the
kerneldoc.
While preparing v2 I also noticed that the tabs used in the kerneldoc
comments were causing the kerneldoc to get parsed incorrectly so I also
fixed this up (including for d_unhashed, which is otherwise unrelated).
Testing: x86 defconfig build + boot; make htmldocs for the kerneldoc
warning. objdump shows there are code generation changes.
Link: https://lore.kernel.org/all/20231022164520.915013-1-vegard.nossum@oracle.com/
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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With the new ordering in __dentry_kill() it has become redundant -
it's set if and only if both DCACHE_DENTRY_KILLED and DCACHE_SHRINK_LIST
are set.
We set it in __dentry_kill(), after having set DCACHE_DENTRY_KILLED
with the only condition being that DCACHE_SHRINK_LIST is there;
all of that is done without dropping ->d_lock and the only place
that checks that flag (shrink_dentry_list()) does so under ->d_lock,
after having found the victim on its shrink list. Since DCACHE_SHRINK_LIST
is set only when placing dentry into shrink list and removed only by
shrink_dentry_list() itself, a check for DCACHE_DENTRY_KILLED in
there would be equivalent to check for DCACHE_MAY_FREE.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... now that we never call d_genocide() other than from kill_litter_super()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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now that the only user of d_instantiate_anon() is gone...
[braino fix folded - kudos to Dan Carpenter]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Saves a pointer per struct dentry and actually makes the things less
clumsy. Cleaned the d_walk() and dcache_readdir() a bit by use
of hlist_for_... iterators.
A couple of new helpers - d_first_child() and d_next_sibling(),
to make the expressions less awful.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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no users left
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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there's a strange comment in front of d_lookup() declaration:
/* appendix may either be NULL or be used for transname suffixes */
Looks like nobody had been curious enough to track its history;
it predates git, it predates bitkeeper and if you look through
the pre-BK trees, you finally arrive at this in 2.1.44-for-davem:
/* appendix may either be NULL or be used for transname suffixes */
-extern struct dentry * d_lookup(struct inode * dir, struct qstr * name,
- struct qstr * appendix);
+extern struct dentry * d_lookup(struct dentry * dir, struct qstr * name);
In other words, it refers to the third argument d_lookup() used to have
back then. It had been introduced in 2.1.43-pre, on June 12 1997,
along with d_lookup(), only to be removed by July 4 1997, presumably
when the Cthulhu-awful thing it used to be used for (look for
CONFIG_TRANS_NAMES in 2.1.43-pre, and keep a heavy-duty barfbag
ready) had been, er, noticed and recognized for what it had been.
Despite the appendectomy, the comment remained. Some things really
need to be put out of their misery...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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d_instantiate_unique() had been gone for 7 years; __d_lookup...()
and shrink_dcache_for_umount() are fs/internal.h fodder.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Introduced in 2015 and never had any in-tree users...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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the last user gone in 2021...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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For bits 20..22 (inode type cached in ->d_flags) turn the definitions into
expressions like (5 << 20); everything else turns into straight use of
BIT()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This is beyond ridiculous. There is a reason why that thing is
cacheline-aligned...
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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New helper for bcachefs - bcachefs doesn't want the
inode_dec_link_count() call that d_tmpfile does, it handles i_nlink on
its own atomically with other btree updates
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs tmpfile updates from Al Viro:
"Miklos' ->tmpfile() signature change; pass an unopened struct file to
it, let it open the damn thing. Allows to add tmpfile support to FUSE"
* tag 'pull-tmpfile' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fuse: implement ->tmpfile()
vfs: open inside ->tmpfile()
vfs: move open right after ->tmpfile()
vfs: make vfs_tmpfile() static
ovl: use vfs_tmpfile_open() helper
cachefiles: use vfs_tmpfile_open() helper
cachefiles: only pass inode to *mark_inode_inuse() helpers
cachefiles: tmpfile error handling cleanup
hugetlbfs: cleanup mknod and tmpfile
vfs: add vfs_tmpfile_open() helper
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This is in preparation for adding tmpfile support to fuse, which requires
that the tmpfile creation and opening are done as a single operation.
Replace the 'struct dentry *' argument of i_op->tmpfile with
'struct file *'.
Call finish_open_simple() as the last thing in ->tmpfile() instances (may
be omitted in the error case).
Change d_tmpfile() argument to 'struct file *' as well to make callers more
readable.
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Pull ceph updates from Ilya Dryomov:
"We have a good pile of various fixes and cleanups from Xiubo, Jeff,
Luis and others, almost exclusively in the filesystem.
Several patches touch files outside of our normal purview to set the
stage for bringing in Jeff's long awaited ceph+fscrypt series in the
near future. All of them have appropriate acks and sat in linux-next
for a while"
* tag 'ceph-for-5.20-rc1' of https://github.com/ceph/ceph-client: (27 commits)
libceph: clean up ceph_osdc_start_request prototype
libceph: fix ceph_pagelist_reserve() comment typo
ceph: remove useless check for the folio
ceph: don't truncate file in atomic_open
ceph: make f_bsize always equal to f_frsize
ceph: flush the dirty caps immediatelly when quota is approaching
libceph: print fsid and epoch with osd id
libceph: check pointer before assigned to "c->rules[]"
ceph: don't get the inline data for new creating files
ceph: update the auth cap when the async create req is forwarded
ceph: make change_auth_cap_ses a global symbol
ceph: fix incorrect old_size length in ceph_mds_request_args
ceph: switch back to testing for NULL folio->private in ceph_dirty_folio
ceph: call netfs_subreq_terminated with was_async == false
ceph: convert to generic_file_llseek
ceph: fix the incorrect comment for the ceph_mds_caps struct
ceph: don't leak snap_rwsem in handle_cap_grant
ceph: prevent a client from exceeding the MDS maximum xattr size
ceph: choose auth MDS for getxattr with the Xs caps
ceph: add session already open notify support
...
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Compare dentry name with case-exact name, return true if names
are same, or false.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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__d_lookup_done() wakes waiters on dentry->d_wait. On PREEMPT_RT we are
not allowed to do that with preemption disabled, since the wakeup
acquired wait_queue_head::lock, which is a "sleeping" spinlock on RT.
Calling it under dentry->d_lock is not a problem, since that is also a
"sleeping" spinlock on the same configs. Unfortunately, two of its
callers (__d_add() and __d_move()) are holding more than just ->d_lock
and that needs to be dealt with.
The key observation is that wakeup can be moved to any point before
dropping ->d_lock.
As a first step to solve this, move the wake up outside of the
hlist_bl_lock() held section.
This is safe because:
Waiters get inserted into ->d_wait only after they'd taken ->d_lock
and observed DCACHE_PAR_LOOKUP in flags. As long as they are
woken up (and evicted from the queue) between the moment __d_lookup_done()
has removed DCACHE_PAR_LOOKUP and dropping ->d_lock, we are safe,
since the waitqueue ->d_wait points to won't get destroyed without
having __d_lookup_done(dentry) called (under ->d_lock).
->d_wait is set only by d_alloc_parallel() and only in case when
it returns a freshly allocated in-lookup dentry. Whenever that happens,
we are guaranteed that __d_lookup_done() will be called for resulting
dentry (under ->d_lock) before the wq in question gets destroyed.
With two exceptions wq lives in call frame of the caller of
d_alloc_parallel() and we have an explicit d_lookup_done() on the
resulting in-lookup dentry before we leave that frame.
One of those exceptions is nfs_call_unlink(), where wq is embedded into
(dynamically allocated) struct nfs_unlinkdata. It is destroyed in
nfs_async_unlink_release() after an explicit d_lookup_done() on the
dentry wq went into.
Remaining exception is d_add_ci(). There wq is what we'd found in
->d_wait of d_add_ci() argument. Callers of d_add_ci() are two
instances of ->d_lookup() and they must have been given an in-lookup
dentry. Which means that they'd been called by __lookup_slow() or
lookup_open(), with wq in the call frame of one of those.
Result of d_alloc_parallel() in d_add_ci() is fed to
d_splice_alias(), which either returns non-NULL (and d_add_ci() does
d_lookup_done()) or feeds dentry to __d_add() that will do
__d_lookup_done() under ->d_lock. That concludes the analysis.
Let __d_lookup_unhash():
1) Lock the lookup hash and clear DCACHE_PAR_LOOKUP
2) Unhash the dentry
3) Retrieve and clear dentry::d_wait
4) Unlock the hash and return the retrieved waitqueue head pointer
5) Let the caller handle the wake up.
6) Rename __d_lookup_done() to __d_lookup_unhash_wake() to enforce
build failures for OOT code that used __d_lookup_done() and is not
aware of the new return value.
This does not yet solve the PREEMPT_RT problem completely because
preemption is still disabled due to i_dir_seq being held for write. This
will be addressed in subsequent steps.
An alternative solution would be to switch the waitqueue to a simple
waitqueue, but aside of Linus not being a fan of them, moving the wake up
closer to the place where dentry::lock is unlocked reduces lock contention
time for the woken up waiter.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lkml.kernel.org/r/20220613140712.77932-3-bigeasy@linutronix.de
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.
To help with this maintenance let's start by moving sysctls to places
where they actually belong. The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.
So move the dcache sysctl clutter out of kernel/sysctl.c. This is a
small one-off entry, perhaps later we can simplify this representation,
but for now we use the helpers we have. We won't know how we can
simplify this further untl we're fully done with the cleanup.
[arnd@arndb.de: avoid unused-function warning]
Link: https://lkml.kernel.org/r/20211203190123.874239-2-arnd@kernel.org
Link: https://lkml.kernel.org/r/20211129205548.605569-4-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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similar to d_find_alias(inode), except that
* the caller must be holding rcu_read_lock()
* inode must not be freed until matching rcu_read_unlock()
* result is *NOT* pinned and can only be dereferenced until
the matching rcu_read_unlock().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt to start cleaning it up by splitting out
mathematical helpers.
At the same time convert users in header and lib folder to use new
header. Though for time being include new header back to kernel.h to
avoid twisted indirected includes for existing users.
[sfr@canb.auug.org.au: fix powerpc build]
Link: https://lkml.kernel.org/r/20201029150809.13059608@canb.auug.org.au
Link: https://lkml.kernel.org/r/20201028173212.41768-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Originally we used the term "encrypted name" or "ciphertext name" to
mean the encoded filename that is shown when an encrypted directory is
listed without its key. But these terms are ambiguous since they also
mean the filename stored on-disk. "Encrypted name" is especially
ambiguous since it could also be understood to mean "this filename is
encrypted on-disk", similar to "encrypted file".
So we've started calling these encoded names "no-key names" instead.
Therefore, rename DCACHE_ENCRYPTED_NAME to DCACHE_NOKEY_NAME to avoid
confusion about what this flag means.
Link: https://lore.kernel.org/r/20200924042624.98439-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
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A sequence counter write side critical section must be protected by some
form of locking to serialize writers. A plain seqcount_t does not
contain the information of which lock must be held when entering a write
side critical section.
Use the new seqcount_spinlock_t data type, which allows to associate a
spinlock with the sequence counter. This enables lockdep to verify that
the spinlock used for writer serialization is held when the write side
critical section is entered.
If lockdep is disabled this lock association is compiled out and has
neither storage size nor runtime overhead.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-19-a.darwish@linutronix.de
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DCACHE_DONTCACHE indicates a dentry should not be cached on final
dput().
Also add a helper function to mark DCACHE_DONTCACHE on all dentries
pointing to a specific inode when that inode is being set I_DONTCACHE.
This facilitates dropping dentry references to inodes sooner which
require eviction to swap S_DAX mode.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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There are 4 callers; two proceed to check if result is positive and
fail with ENOENT if it isn't; one (in handle_lookup_down()) is
guaranteed to yield positive and one (in lookup_fast()) is _preceded_
by positivity check.
However, follow_managed() on a negative dentry is a (fairly cheap)
no-op on anything other than autofs. And negative autofs dentries
are never hashed, so lookup_fast() is not going to run into one
of those. Moreover, successful follow_managed() on a _positive_
dentry never yields a negative one (and we significantly rely upon
that in callers of lookup_fast()).
In other words, we can easily transpose the positivity check and
the call of follow_managed() in lookup_fast(). And that allows
to fold the positivity check *into* follow_managed(), simplifying
life for the code downstream of its calls.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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There are 3 remaining files without an extension inside the fs docs
dir.
Manually convert them to ReST.
In the case of the nfs/exporting.rst file, as the nfs docs
aren't ported yet, I opted to convert and add a :orphan: there,
with should be removed when it gets added into a nfs-specific
part of the fs documentation.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs mount updates from Al Viro:
"The first part of mount updates.
Convert filesystems to use the new mount API"
* 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
mnt_init(): call shmem_init() unconditionally
constify ksys_mount() string arguments
don't bother with registering rootfs
init_rootfs(): don't bother with init_ramfs_fs()
vfs: Convert smackfs to use the new mount API
vfs: Convert selinuxfs to use the new mount API
vfs: Convert securityfs to use the new mount API
vfs: Convert apparmorfs to use the new mount API
vfs: Convert openpromfs to use the new mount API
vfs: Convert xenfs to use the new mount API
vfs: Convert gadgetfs to use the new mount API
vfs: Convert oprofilefs to use the new mount API
vfs: Convert ibmasmfs to use the new mount API
vfs: Convert qib_fs/ipathfs to use the new mount API
vfs: Convert efivarfs to use the new mount API
vfs: Convert configfs to use the new mount API
vfs: Convert binfmt_misc to use the new mount API
convenience helper: get_tree_single()
convenience helper get_tree_nodev()
vfs: Kill sget_userns()
...
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A recent documentation conversion renamed this file but forgot
to update the links.
Fixes: af96c1e304f7 ("docs: filesystems: vfs: Convert vfs.txt to RST")
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Pull fscrypt updates from Ted Ts'o:
"Clean up fscrypt's dcache revalidation support, and other
miscellaneous cleanups"
* tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
fscrypt: cache decrypted symlink target in ->i_link
vfs: use READ_ONCE() to access ->i_link
fscrypt: fix race where ->lookup() marks plaintext dentry as ciphertext
fscrypt: only set dentry_operations on ciphertext dentries
fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory
fscrypt: fix race allowing rename() and link() of ciphertext dentries
fscrypt: clean up and improve dentry revalidation
fscrypt: use READ_ONCE() to access ->i_crypt_info
fscrypt: remove WARN_ON_ONCE() when decryption fails
fscrypt: drop inode argument from fscrypt_get_ctx()
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Make various improvements to fscrypt dentry revalidation:
- Don't try to handle the case where the per-directory key is removed,
as this can't happen without the inode (and dentries) being evicted.
- Flag ciphertext dentries rather than plaintext dentries, since it's
ciphertext dentries that need the special handling.
- Avoid doing unnecessary work for non-ciphertext dentries.
- When revalidating ciphertext dentries, try to set up the directory's
i_crypt_info to make sure the key is really still absent, rather than
invalidating all negative dentries as the previous code did. An old
comment suggested we can't do this for locking reasons, but AFAICT
this comment was outdated and it actually works fine.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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No modular uses since introducion of alloc_file_pseudo(),
and the only non-modular user not in alloc_file_pseudo()
had actually been wrong - should've been d_alloc_anon().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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For lockless accesses to dentries we don't have pinned we rely
(among other things) upon having an RCU delay between dropping
the last reference and actually freeing the memory.
On the other hand, for things like pipes and sockets we neither
do that kind of lockless access, nor want to deal with the
overhead of an RCU delay every time a socket gets closed.
So delay was made optional - setting DCACHE_RCUACCESS in ->d_flags
made sure it would happen. We tried to avoid setting it unless
we knew we need it. Unfortunately, that had led to recurring
class of bugs, in which we missed the need to set it.
We only really need it for dentries that are created by
d_alloc_pseudo(), so let's not bother with trying to be smart -
just make having an RCU delay the default. The ones that do
*not* get it set the replacement flag (DCACHE_NORCU) and we'd
better use that sparingly. d_alloc_pseudo() is the only
such user right now.
FWIW, the race that finally prompted that switch had been
between __lock_parent() of immediate subdirectory of what's
currently the root of a disconnected tree (e.g. from
open-by-handle in progress) racing with d_splice_alias()
elsewhere picking another alias for the same inode, either
on outright corrupted fs image, or (in case of open-by-handle
on NFS) that subdirectory having been just moved on server.
It's not easy to hit, so the sky is not falling, but that's
not the first race on similar missed cases and the logics
for settinf DCACHE_RCUACCESS has gotten ridiculously
convoluted.
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The current dentry number tracking code doesn't distinguish between
positive & negative dentries. It just reports the total number of
dentries in the LRU lists.
As excessive number of negative dentries can have an impact on system
performance, it will be wise to track the number of positive and
negative dentries separately.
This patch adds tracking for the total number of negative dentries in
the system LRU lists and reports it in the 5th field in the
/proc/sys/fs/dentry-state file. The number, however, does not include
negative dentries that are in flight but not in the LRU yet as well as
those in the shrinker lists which are on the way out anyway.
The number of positive dentries in the LRU lists can be roughly found by
subtracting the number of negative dentries from the unused count.
Matthew Wilcox had confirmed that since the introduction of the
dentry_stat structure in 2.1.60, the dummy array was there, probably for
future extension. They were not replacements of pre-existing fields.
So no sane applications that read the value of /proc/sys/fs/dentry-state
will do dummy thing if the last 2 fields of the sysctl parameter are not
zero. IOW, it will be safe to use one of the dummy array entry for
negative dentry count.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
"This contains two new features:
- Stack file operations: this allows removal of several hacks from
the VFS, proper interaction of read-only open files with copy-up,
possibility to implement fs modifying ioctls properly, and others.
- Metadata only copy-up: when file is on lower layer and only
metadata is modified (except size) then only copy up the metadata
and continue to use the data from the lower file"
* tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (66 commits)
ovl: Enable metadata only feature
ovl: Do not do metacopy only for ioctl modifying file attr
ovl: Do not do metadata only copy-up for truncate operation
ovl: add helper to force data copy-up
ovl: Check redirect on index as well
ovl: Set redirect on upper inode when it is linked
ovl: Set redirect on metacopy files upon rename
ovl: Do not set dentry type ORIGIN for broken hardlinks
ovl: Add an inode flag OVL_CONST_INO
ovl: Treat metacopy dentries as type OVL_PATH_MERGE
ovl: Check redirects for metacopy files
ovl: Move some dir related ovl_lookup_single() code in else block
ovl: Do not expose metacopy only dentry from d_real()
ovl: Open file with data except for the case of fsync
ovl: Add helper ovl_inode_realdata()
ovl: Store lower data inode in ovl_inode
ovl: Fix ovl_getattr() to get number of blocks from lower
ovl: Add helper ovl_dentry_lowerdata() to get lower data dentry
ovl: Copy up meta inode data from lowest data inode
ovl: Modify ovl_lookup() and friends to lookup metacopy dentry
...
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull misc vfs updates from Al Viro:
"Misc cleanups from various folks all over the place
I expected more fs/dcache.c cleanups this cycle, so that went into a
separate branch. Said cleanups have missed the window, so in the
hindsight it could've gone into work.misc instead. Decided not to
cherry-pick, thus the 'work.dcache' branch"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: dcache: Use true and false for boolean values
fold generic_readlink() into its only caller
fs: shave 8 bytes off of struct inode
fs: Add more kernel-doc to the produced documentation
fs: Fix attr.c kernel-doc
removed extra extern file_fdatawait_range
* 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
kill dentry_update_name_case()
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The only user is fuse_create_new_entry(), and there it's used to
mitigate the same mkdir/open-by-handle race as in nfs_mkdir().
The same solution applies - unhash the mkdir argument, then
call d_splice_alias() and if that returns a reference to preexisting
alias, dput() and report success. ->mkdir() argument left unhashed
negative with the preexisting alias moved in the right place is just
fine from the ->mkdir() callers point of view.
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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