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, 215 insertions, 0 deletions

diff --git a/fs/nilfs2/ifile.c b/fs/nilfs2/ifile.c
new file mode 100644
index 000000000..c99e1e635
--- /dev/null
+++ b/fs/nilfs2/ifile.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * NILFS inode file
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * Written by Amagai Yoshiji.
+ * Revised by Ryusuke Konishi.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include "nilfs.h"
+#include "mdt.h"
+#include "alloc.h"
+#include "ifile.h"
+#include "cpfile.h"
+
+/**
+ * struct nilfs_ifile_info - on-memory private data of ifile
+ * @mi: on-memory private data of metadata file
+ * @palloc_cache: persistent object allocator cache of ifile
+ */
+struct nilfs_ifile_info {
+	struct nilfs_mdt_info mi;
+	struct nilfs_palloc_cache palloc_cache;
+};
+
+static inline struct nilfs_ifile_info *NILFS_IFILE_I(struct inode *ifile)
+{
+	return (struct nilfs_ifile_info *)NILFS_MDT(ifile);
+}
+
+/**
+ * nilfs_ifile_create_inode - create a new disk inode
+ * @ifile: ifile inode
+ * @out_ino: pointer to a variable to store inode number
+ * @out_bh: buffer_head contains newly allocated disk inode
+ *
+ * nilfs_ifile_create_inode() allocates a new inode in the ifile metadata
+ * file and stores the inode number in the variable pointed to by @out_ino,
+ * as well as storing the ifile's buffer with the disk inode in the location
+ * pointed to by @out_bh.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOMEM	- Insufficient memory available.
+ * * %-ENOSPC	- No inode left.
+ */
+int nilfs_ifile_create_inode(struct inode *ifile, u64 *out_ino,
+			     struct buffer_head **out_bh)
+{
+	struct nilfs_palloc_req req;
+	int ret;
+
+	req.pr_entry_nr = NILFS_FIRST_INO(ifile->i_sb);
+	req.pr_entry_bh = NULL;
+
+	ret = nilfs_palloc_prepare_alloc_entry(ifile, &req, false);
+	if (!ret) {
+		ret = nilfs_palloc_get_entry_block(ifile, req.pr_entry_nr, 1,
+						   &req.pr_entry_bh);
+		if (ret < 0)
+			nilfs_palloc_abort_alloc_entry(ifile, &req);
+	}
+	if (ret < 0) {
+		brelse(req.pr_entry_bh);
+		return ret;
+	}
+	nilfs_palloc_commit_alloc_entry(ifile, &req);
+	mark_buffer_dirty(req.pr_entry_bh);
+	nilfs_mdt_mark_dirty(ifile);
+	*out_ino = req.pr_entry_nr;
+	*out_bh = req.pr_entry_bh;
+	return 0;
+}
+
+/**
+ * nilfs_ifile_delete_inode - delete a disk inode
+ * @ifile: ifile inode
+ * @ino: inode number
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOENT	- Inode number unallocated.
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_ifile_delete_inode(struct inode *ifile, u64 ino)
+{
+	struct nilfs_palloc_req req = {
+		.pr_entry_nr = ino, .pr_entry_bh = NULL
+	};
+	struct nilfs_inode *raw_inode;
+	size_t offset;
+	int ret;
+
+	ret = nilfs_palloc_prepare_free_entry(ifile, &req);
+	if (!ret) {
+		ret = nilfs_palloc_get_entry_block(ifile, req.pr_entry_nr, 0,
+						   &req.pr_entry_bh);
+		if (ret < 0)
+			nilfs_palloc_abort_free_entry(ifile, &req);
+	}
+	if (ret < 0) {
+		brelse(req.pr_entry_bh);
+		return ret;
+	}
+
+	offset = nilfs_palloc_entry_offset(ifile, req.pr_entry_nr,
+					   req.pr_entry_bh);
+	raw_inode = kmap_local_folio(req.pr_entry_bh->b_folio, offset);
+	raw_inode->i_flags = 0;
+	kunmap_local(raw_inode);
+
+	mark_buffer_dirty(req.pr_entry_bh);
+	brelse(req.pr_entry_bh);
+
+	nilfs_palloc_commit_free_entry(ifile, &req);
+
+	return 0;
+}
+
+int nilfs_ifile_get_inode_block(struct inode *ifile, u64 ino,
+				struct buffer_head **out_bh)
+{
+	struct super_block *sb = ifile->i_sb;
+	int err;
+
+	if (unlikely(!NILFS_VALID_INODE(sb, ino))) {
+		nilfs_error(sb, "bad inode number: %llu", ino);
+		return -EINVAL;
+	}
+
+	err = nilfs_palloc_get_entry_block(ifile, ino, 0, out_bh);
+	if (unlikely(err))
+		nilfs_warn(sb, "error %d reading inode: ino=%llu", err, ino);
+	return err;
+}
+
+/**
+ * nilfs_ifile_count_free_inodes - calculate free inodes count
+ * @ifile: ifile inode
+ * @nmaxinodes: current maximum of available inodes count [out]
+ * @nfreeinodes: free inodes count [out]
+ *
+ * Return: 0 on success, or a negative error code on failure.
+ */
+int nilfs_ifile_count_free_inodes(struct inode *ifile,
+				    u64 *nmaxinodes, u64 *nfreeinodes)
+{
+	u64 nused;
+	int err;
+
+	*nmaxinodes = 0;
+	*nfreeinodes = 0;
+
+	nused = atomic64_read(&NILFS_I(ifile)->i_root->inodes_count);
+	err = nilfs_palloc_count_max_entries(ifile, nused, nmaxinodes);
+	if (likely(!err))
+		*nfreeinodes = *nmaxinodes - nused;
+	return err;
+}
+
+/**
+ * nilfs_ifile_read - read or get ifile inode
+ * @sb: super block instance
+ * @root: root object
+ * @cno: number of checkpoint entry to read
+ * @inode_size: size of an inode
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EINVAL	- Invalid checkpoint.
+ * * %-ENOMEM	- Insufficient memory available.
+ * * %-EIO	- I/O error (including metadata corruption).
+ */
+int nilfs_ifile_read(struct super_block *sb, struct nilfs_root *root,
+		     __u64 cno, size_t inode_size)
+{
+	struct the_nilfs *nilfs;
+	struct inode *ifile;
+	int err;
+
+	ifile = nilfs_iget_locked(sb, root, NILFS_IFILE_INO);
+	if (unlikely(!ifile))
+		return -ENOMEM;
+	if (!(inode_state_read_once(ifile) & I_NEW))
+		goto out;
+
+	err = nilfs_mdt_init(ifile, NILFS_MDT_GFP,
+			     sizeof(struct nilfs_ifile_info));
+	if (err)
+		goto failed;
+
+	err = nilfs_palloc_init_blockgroup(ifile, inode_size);
+	if (err)
+		goto failed;
+
+	nilfs_palloc_setup_cache(ifile, &NILFS_IFILE_I(ifile)->palloc_cache);
+
+	nilfs = sb->s_fs_info;
+	err = nilfs_cpfile_read_checkpoint(nilfs->ns_cpfile, cno, root, ifile);
+	if (err)
+		goto failed;
+
+	unlock_new_inode(ifile);
+ out:
+	return 0;
+ failed:
+	iget_failed(ifile);
+	return err;
+}