ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 247 insertions, 0 deletions

diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c
new file mode 100644
index 000000000..4f6bf5926
--- /dev/null
+++ b/fs/f2fs/shrinker.c
@@ -0,0 +1,247 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * f2fs shrinker support
+ *   the basic infra was copied from fs/ubifs/shrinker.c
+ *
+ * Copyright (c) 2015 Motorola Mobility
+ * Copyright (c) 2015 Jaegeuk Kim <jaegeuk@kernel.org>
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+
+#include "f2fs.h"
+#include "node.h"
+
+static LIST_HEAD(f2fs_list);
+static DEFINE_SPINLOCK(f2fs_list_lock);
+static unsigned int shrinker_run_no;
+
+static unsigned long __count_nat_entries(struct f2fs_sb_info *sbi)
+{
+	return NM_I(sbi)->nat_cnt[RECLAIMABLE_NAT];
+}
+
+static unsigned long __count_free_nids(struct f2fs_sb_info *sbi)
+{
+	long count = NM_I(sbi)->nid_cnt[FREE_NID] - MAX_FREE_NIDS;
+
+	return count > 0 ? count : 0;
+}
+
+static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi,
+					enum extent_type type)
+{
+	struct extent_tree_info *eti = &sbi->extent_tree[type];
+
+	return atomic_read(&eti->total_zombie_tree) +
+				atomic_read(&eti->total_ext_node);
+}
+
+unsigned long f2fs_shrink_count(struct shrinker *shrink,
+				struct shrink_control *sc)
+{
+	struct f2fs_sb_info *sbi;
+	struct list_head *p;
+	unsigned long count = 0;
+
+	spin_lock(&f2fs_list_lock);
+	p = f2fs_list.next;
+	while (p != &f2fs_list) {
+		sbi = list_entry(p, struct f2fs_sb_info, s_list);
+
+		/* stop f2fs_put_super */
+		if (!mutex_trylock(&sbi->umount_mutex)) {
+			p = p->next;
+			continue;
+		}
+		spin_unlock(&f2fs_list_lock);
+
+		/* count read extent cache entries */
+		count += __count_extent_cache(sbi, EX_READ);
+
+		/* count block age extent cache entries */
+		count += __count_extent_cache(sbi, EX_BLOCK_AGE);
+
+		/* count clean nat cache entries */
+		count += __count_nat_entries(sbi);
+
+		/* count free nids cache entries */
+		count += __count_free_nids(sbi);
+
+		spin_lock(&f2fs_list_lock);
+		p = p->next;
+		mutex_unlock(&sbi->umount_mutex);
+	}
+	spin_unlock(&f2fs_list_lock);
+	return count ?: SHRINK_EMPTY;
+}
+
+unsigned long f2fs_shrink_scan(struct shrinker *shrink,
+				struct shrink_control *sc)
+{
+	unsigned long nr = sc->nr_to_scan;
+	struct f2fs_sb_info *sbi;
+	struct list_head *p;
+	unsigned int run_no;
+	unsigned long freed = 0;
+
+	spin_lock(&f2fs_list_lock);
+	do {
+		run_no = ++shrinker_run_no;
+	} while (run_no == 0);
+	p = f2fs_list.next;
+	while (p != &f2fs_list) {
+		sbi = list_entry(p, struct f2fs_sb_info, s_list);
+
+		if (sbi->shrinker_run_no == run_no)
+			break;
+
+		/* stop f2fs_put_super */
+		if (!mutex_trylock(&sbi->umount_mutex)) {
+			p = p->next;
+			continue;
+		}
+		spin_unlock(&f2fs_list_lock);
+
+		sbi->shrinker_run_no = run_no;
+
+		/* shrink extent cache entries */
+		freed += f2fs_shrink_age_extent_tree(sbi, nr >> 2);
+
+		/* shrink read extent cache entries */
+		if (freed < nr)
+			freed += f2fs_shrink_read_extent_tree(sbi, nr >> 2);
+
+		/* shrink clean nat cache entries */
+		if (freed < nr)
+			freed += f2fs_try_to_free_nats(sbi, nr - freed);
+
+		/* shrink free nids cache entries */
+		if (freed < nr)
+			freed += f2fs_try_to_free_nids(sbi, nr - freed);
+
+		spin_lock(&f2fs_list_lock);
+		p = p->next;
+		list_move_tail(&sbi->s_list, &f2fs_list);
+		mutex_unlock(&sbi->umount_mutex);
+		if (freed >= nr)
+			break;
+	}
+	spin_unlock(&f2fs_list_lock);
+	return freed;
+}
+
+unsigned int f2fs_donate_files(void)
+{
+	struct f2fs_sb_info *sbi;
+	struct list_head *p;
+	unsigned int donate_files = 0;
+
+	spin_lock(&f2fs_list_lock);
+	p = f2fs_list.next;
+	while (p != &f2fs_list) {
+		sbi = list_entry(p, struct f2fs_sb_info, s_list);
+
+		/* stop f2fs_put_super */
+		if (!mutex_trylock(&sbi->umount_mutex)) {
+			p = p->next;
+			continue;
+		}
+		spin_unlock(&f2fs_list_lock);
+
+		donate_files += sbi->donate_files;
+
+		spin_lock(&f2fs_list_lock);
+		p = p->next;
+		mutex_unlock(&sbi->umount_mutex);
+	}
+	spin_unlock(&f2fs_list_lock);
+
+	return donate_files;
+}
+
+static unsigned int do_reclaim_caches(struct f2fs_sb_info *sbi,
+				unsigned int reclaim_caches_kb)
+{
+	struct inode *inode;
+	struct f2fs_inode_info *fi;
+	unsigned int nfiles = sbi->donate_files;
+	pgoff_t npages = reclaim_caches_kb >> (PAGE_SHIFT - 10);
+
+	while (npages && nfiles--) {
+		pgoff_t len;
+
+		spin_lock(&sbi->inode_lock[DONATE_INODE]);
+		if (list_empty(&sbi->inode_list[DONATE_INODE])) {
+			spin_unlock(&sbi->inode_lock[DONATE_INODE]);
+			break;
+		}
+		fi = list_first_entry(&sbi->inode_list[DONATE_INODE],
+					struct f2fs_inode_info, gdonate_list);
+		list_move_tail(&fi->gdonate_list, &sbi->inode_list[DONATE_INODE]);
+		inode = igrab(&fi->vfs_inode);
+		spin_unlock(&sbi->inode_lock[DONATE_INODE]);
+
+		if (!inode)
+			continue;
+
+		inode_lock(inode);
+		if (!is_inode_flag_set(inode, FI_DONATE_FINISHED)) {
+			len = fi->donate_end - fi->donate_start + 1;
+			npages = npages < len ? 0 : npages - len;
+
+			invalidate_inode_pages2_range(inode->i_mapping,
+					fi->donate_start, fi->donate_end);
+			set_inode_flag(inode, FI_DONATE_FINISHED);
+		}
+		inode_unlock(inode);
+
+		iput(inode);
+		cond_resched();
+	}
+	return npages << (PAGE_SHIFT - 10);
+}
+
+void f2fs_reclaim_caches(unsigned int reclaim_caches_kb)
+{
+	struct f2fs_sb_info *sbi;
+	struct list_head *p;
+
+	spin_lock(&f2fs_list_lock);
+	p = f2fs_list.next;
+	while (p != &f2fs_list && reclaim_caches_kb) {
+		sbi = list_entry(p, struct f2fs_sb_info, s_list);
+
+		/* stop f2fs_put_super */
+		if (!mutex_trylock(&sbi->umount_mutex)) {
+			p = p->next;
+			continue;
+		}
+		spin_unlock(&f2fs_list_lock);
+
+		reclaim_caches_kb = do_reclaim_caches(sbi, reclaim_caches_kb);
+
+		spin_lock(&f2fs_list_lock);
+		p = p->next;
+		mutex_unlock(&sbi->umount_mutex);
+	}
+	spin_unlock(&f2fs_list_lock);
+}
+
+void f2fs_join_shrinker(struct f2fs_sb_info *sbi)
+{
+	spin_lock(&f2fs_list_lock);
+	list_add_tail(&sbi->s_list, &f2fs_list);
+	spin_unlock(&f2fs_list_lock);
+}
+
+void f2fs_leave_shrinker(struct f2fs_sb_info *sbi)
+{
+	f2fs_shrink_read_extent_tree(sbi, __count_extent_cache(sbi, EX_READ));
+	f2fs_shrink_age_extent_tree(sbi,
+				__count_extent_cache(sbi, EX_BLOCK_AGE));
+
+	spin_lock(&f2fs_list_lock);
+	list_del_init(&sbi->s_list);
+	spin_unlock(&f2fs_list_lock);
+}