kernel/git/stable/linux.git/fs/dcache.c, branch linux-6.7.y

fast_dput(): handle underflows gracefully

2024-02-05T20:16:57+00:00

[ Upstream commit 504e08cebe1d4e1efe25f915234f646e74a364a8 ] If refcount is less than 1, we should just warn, unlock dentry and return true, so that the caller doesn't try to do anything else. Taking care of that leaves the rest of "lockref_put_return() has failed" case equivalent to "decrement refcount and rejoin the normal slow path after the point where we grab ->d_lock". NOTE: lockref_put_return() is strictly a fastpath thing - unlike the rest of lockref primitives, it does not contain a fallback. Caller (and it looks like fast_dput() is the only legitimate one in the entire kernel) has to do that itself. Reasons for lockref_put_return() failures: * ->d_lock held by somebody * refcount <= 0 * ... or an architecture not supporting lockref use of cmpxchg - sparc, anything non-SMP, config with spinlock debugging... We could add a fallback, but it would be a clumsy API - we'd have to distinguish between: (1) refcount > 1 - decremented, lock not held on return (2) refcount < 1 - left alone, probably no sense to hold the lock (3) refcount is 1, no cmphxcg - decremented, lock held on return (4) refcount is 1, cmphxcg supported - decremented, lock *NOT* held on return. We want to return with no lock held in case (4); that's the whole point of that thing. We very much do not want to have the fallback in case (3) return without a lock, since the caller might have to retake it in that case. So it wouldn't be more convenient than doing the fallback in the caller and it would be very easy to screw up, especially since the test coverage would suck - no way to test (3) and (4) on the same kernel build. Reviewed-by: Christian Brauner Signed-off-by: Al Viro Signed-off-by: Sasha Levin

Merge tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-11-03T06:53:31+00:00

Pull non-MM updates from Andrew Morton: "As usual, lots of singleton and doubleton patches all over the tree and there's little I can say which isn't in the individual changelogs. The lengthier patch series are - 'kdump: use generic functions to simplify crashkernel reservation in arch', from Baoquan He. This is mainly cleanups and consolidation of the 'crashkernel=' kernel parameter handling - After much discussion, David Laight's 'minmax: Relax type checks in min() and max()' is here. Hopefully reduces some typecasting and the use of min_t() and max_t() - A group of patches from Oleg Nesterov which clean up and slightly fix our handling of reads from /proc/PID/task/... and which remove task_struct.thread_group" * tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (64 commits) scripts/gdb/vmalloc: disable on no-MMU scripts/gdb: fix usage of MOD_TEXT not defined when CONFIG_MODULES=n .mailmap: add address mapping for Tomeu Vizoso mailmap: update email address for Claudiu Beznea tools/testing/selftests/mm/run_vmtests.sh: lower the ptrace permissions .mailmap: map Benjamin Poirier's address scripts/gdb: add lx_current support for riscv ocfs2: fix a spelling typo in comment proc: test ProtectionKey in proc-empty-vm test proc: fix proc-empty-vm test with vsyscall fs/proc/base.c: remove unneeded semicolon do_io_accounting: use sig->stats_lock do_io_accounting: use __for_each_thread() ocfs2: replace BUG_ON() at ocfs2_num_free_extents() with ocfs2_error() ocfs2: fix a typo in a comment scripts/show_delta: add __main__ judgement before main code treewide: mark stuff as __ro_after_init fs: ocfs2: check status values proc: test /proc/${pid}/statm compiler.h: move __is_constexpr() to compiler.h ...

treewide: mark stuff as __ro_after_init

2023-10-18T21:43:23+00:00

__read_mostly predates __ro_after_init. Many variables which are marked __read_mostly should have been __ro_after_init from day 1. Also, mark some stuff as "const" and "__init" while I'm at it. [akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning] [akpm@linux-foundation.org: coding-style cleanups] Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183 Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton

fs: factor out d_mark_tmpfile()

2023-09-12T03:59:47+00:00

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 Cc: Alexander Viro Cc: Christian Brauner Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Darrick J. Wong Reviewed-by: Christian Brauner

fs/dcache: Replace printk and WARN_ON by WARN

2023-08-19T11:41:11+00:00

Use WARN instead of printk + WARN_ON as reported from coccinelle: ./fs/dcache.c:1667:1-7: SUGGESTION: printk + WARN_ON can be just WARN Signed-off-by: Anh Tuan Phan Message-Id: <20230817163142.117706-1-tuananhlfc@gmail.com> Signed-off-by: Christian Brauner

fs: unexport d_genocide

2023-08-09T05:53:33+00:00

d_genocide is only used by built-in code. Signed-off-by: Christoph Hellwig Message-Id: <20230808161704.1099680-1-hch@lst.de> Signed-off-by: Christian Brauner

Merge tag 'pull-tmpfile' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2022-10-11T02:45:17+00:00

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

vfs: open inside ->tmpfile()

2022-09-24T05:00:00+00:00

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) Signed-off-by: Miklos Szeredi

dentry: Use preempt_[dis|en]able_nested()

2022-09-19T12:35:07+00:00

Replace the open coded CONFIG_PREEMPT_RT conditional preempt_disable/enable() with the new helper. Signed-off-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Acked-by: Christian Brauner (Microsoft) Link: https://lore.kernel.org/r/20220825164131.402717-3-bigeasy@linutronix.de

dcache: move the DCACHE_OP_COMPARE case out of the __d_lookup_rcu loop

2022-08-17T21:33:03+00:00

__d_lookup_rcu() is one of the hottest functions in the kernel on certain loads, and it is complicated by filesystems that might want to have their own name compare function. We can improve code generation by moving the test of DCACHE_OP_COMPARE outside the loop, which makes the loop itself much simpler, at the cost of some code duplication. But both cases end up being simpler, and the "native" direct case-sensitive compare particularly so. Cc: Al Viro Signed-off-by: Linus Torvalds