From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- fs/stack.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 fs/stack.c (limited to 'fs/stack.c') diff --git a/fs/stack.c b/fs/stack.c new file mode 100644 index 000000000..d8c782e06 --- /dev/null +++ b/fs/stack.c @@ -0,0 +1,76 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +/* does _NOT_ require i_rwsem to be held. + * + * This function cannot be inlined since i_size_{read,write} is rather + * heavy-weight on 32-bit systems + */ +void fsstack_copy_inode_size(struct inode *dst, struct inode *src) +{ + loff_t i_size; + blkcnt_t i_blocks; + + /* + * i_size_read() includes its own seqlocking and protection from + * preemption (see include/linux/fs.h): we need nothing extra for + * that here, and prefer to avoid nesting locks than attempt to keep + * i_size and i_blocks in sync together. + */ + i_size = i_size_read(src); + + /* + * But on 32-bit, we ought to make an effort to keep the two halves of + * i_blocks in sync despite SMP or PREEMPTION - though stat's + * generic_fillattr() doesn't bother, and we won't be applying quotas + * (where i_blocks does become important) at the upper level. + * + * We don't actually know what locking is used at the lower level; + * but if it's a filesystem that supports quotas, it will be using + * i_lock as in inode_add_bytes(). + */ + if (sizeof(i_blocks) > sizeof(long)) + spin_lock(&src->i_lock); + i_blocks = src->i_blocks; + if (sizeof(i_blocks) > sizeof(long)) + spin_unlock(&src->i_lock); + + /* + * If CONFIG_SMP or CONFIG_PREEMPTION on 32-bit, it's vital for + * fsstack_copy_inode_size() to hold some lock around + * i_size_write(), otherwise i_size_read() may spin forever (see + * include/linux/fs.h). We don't necessarily hold i_rwsem when this + * is called, so take i_lock for that case. + * + * And if on 32-bit, continue our effort to keep the two halves of + * i_blocks in sync despite SMP or PREEMPTION: use i_lock for that case + * too, and do both at once by combining the tests. + * + * There is none of this locking overhead in the 64-bit case. + */ + if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long)) + spin_lock(&dst->i_lock); + i_size_write(dst, i_size); + dst->i_blocks = i_blocks; + if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long)) + spin_unlock(&dst->i_lock); +} +EXPORT_SYMBOL_GPL(fsstack_copy_inode_size); + +/* copy all attributes */ +void fsstack_copy_attr_all(struct inode *dest, const struct inode *src) +{ + dest->i_mode = src->i_mode; + dest->i_uid = src->i_uid; + dest->i_gid = src->i_gid; + dest->i_rdev = src->i_rdev; + inode_set_atime_to_ts(dest, inode_get_atime(src)); + inode_set_mtime_to_ts(dest, inode_get_mtime(src)); + inode_set_ctime_to_ts(dest, inode_get_ctime(src)); + dest->i_blkbits = src->i_blkbits; + dest->i_flags = src->i_flags; + set_nlink(dest, src->i_nlink); +} +EXPORT_SYMBOL_GPL(fsstack_copy_attr_all); -- cgit v1.3.1