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, 184 insertions, 0 deletions

diff --git a/fs/nilfs2/gcinode.c b/fs/nilfs2/gcinode.c
new file mode 100644
index 000000000..85379ac23
--- /dev/null
+++ b/fs/nilfs2/gcinode.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Dummy inodes to buffer blocks for garbage collection
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * Written by Seiji Kihara, Amagai Yoshiji, and Ryusuke Konishi.
+ * Revised by Ryusuke Konishi.
+ *
+ */
+/*
+ * This file adds the cache of on-disk blocks to be moved in garbage
+ * collection.  The disk blocks are held with dummy inodes (called
+ * gcinodes), and this file provides lookup function of the dummy
+ * inodes and their buffer read function.
+ *
+ * Buffers and pages held by the dummy inodes will be released each
+ * time after they are copied to a new log.  Dirty blocks made on the
+ * current generation and the blocks to be moved by GC never overlap
+ * because the dirty blocks make a new generation; they rather must be
+ * written individually.
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include <linux/hash.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include "nilfs.h"
+#include "btree.h"
+#include "btnode.h"
+#include "page.h"
+#include "mdt.h"
+#include "dat.h"
+#include "ifile.h"
+
+/*
+ * nilfs_gccache_submit_read_data() - add data buffer and submit read request
+ * @inode - gc inode
+ * @blkoff - dummy offset treated as the key for the page cache
+ * @pbn - physical block number of the block
+ * @vbn - virtual block number of the block, 0 for non-virtual block
+ * @out_bh - indirect pointer to a buffer_head struct to receive the results
+ *
+ * Description: nilfs_gccache_submit_read_data() registers the data buffer
+ * specified by @pbn to the GC pagecache with the key @blkoff.
+ * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOENT	- The block specified with @pbn does not exist.
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
+				   sector_t pbn, __u64 vbn,
+				   struct buffer_head **out_bh)
+{
+	struct buffer_head *bh;
+	int err;
+
+	bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
+	if (unlikely(!bh))
+		return -ENOMEM;
+
+	if (buffer_uptodate(bh))
+		goto out;
+
+	if (pbn == 0) {
+		struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
+
+		err = nilfs_dat_translate(nilfs->ns_dat, vbn, &pbn);
+		if (unlikely(err)) /* -EIO, -ENOMEM, -ENOENT */
+			goto failed;
+	}
+
+	lock_buffer(bh);
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		goto out;
+	}
+
+	if (!buffer_mapped(bh))
+		set_buffer_mapped(bh);
+	bh->b_blocknr = pbn;
+	bh_submit(bh, REQ_OP_READ, bh_end_read);
+	if (vbn)
+		bh->b_blocknr = vbn;
+ out:
+	err = 0;
+	*out_bh = bh;
+
+ failed:
+	folio_unlock(bh->b_folio);
+	folio_put(bh->b_folio);
+	if (unlikely(err))
+		brelse(bh);
+	return err;
+}
+
+/*
+ * nilfs_gccache_submit_read_node() - add node buffer and submit read request
+ * @inode - gc inode
+ * @pbn - physical block number for the block
+ * @vbn - virtual block number for the block
+ * @out_bh - indirect pointer to a buffer_head struct to receive the results
+ *
+ * Description: nilfs_gccache_submit_read_node() registers the node buffer
+ * specified by @vbn to the GC pagecache.  @pbn can be supplied by the
+ * caller to avoid translation of the disk block address.
+ *
+ * Return: 0 on success, or one of the following negative error codes on
+ * failure:
+ * * %-EIO	- I/O error (including metadata corruption).
+ * * %-ENOENT	- Invalid virtual block address.
+ * * %-ENOMEM	- Insufficient memory available.
+ */
+int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
+				   __u64 vbn, struct buffer_head **out_bh)
+{
+	struct inode *btnc_inode = NILFS_I(inode)->i_assoc_inode;
+	int ret;
+
+	ret = nilfs_btnode_submit_block(btnc_inode->i_mapping, vbn ? : pbn, pbn,
+					REQ_OP_READ, out_bh, &pbn);
+	if (ret == -EEXIST) /* internal code (cache hit) */
+		ret = 0;
+	return ret;
+}
+
+int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
+{
+	wait_on_buffer(bh);
+	if (!buffer_uptodate(bh)) {
+		struct inode *inode = bh->b_folio->mapping->host;
+
+		nilfs_err(inode->i_sb,
+			  "I/O error reading %s block for GC (ino=%llu, vblocknr=%llu)",
+			  buffer_nilfs_node(bh) ? "node" : "data",
+			  inode->i_ino, (unsigned long long)bh->b_blocknr);
+		return -EIO;
+	}
+	if (buffer_dirty(bh))
+		return -EEXIST;
+
+	if (buffer_nilfs_node(bh) && nilfs_btree_broken_node_block(bh)) {
+		clear_buffer_uptodate(bh);
+		return -EIO;
+	}
+	mark_buffer_dirty(bh);
+	return 0;
+}
+
+int nilfs_init_gcinode(struct inode *inode)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+
+	inode->i_mode = S_IFREG;
+	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
+	inode->i_mapping->a_ops = &nilfs_buffer_cache_aops;
+
+	ii->i_flags = 0;
+	nilfs_bmap_init_gc(ii->i_bmap);
+
+	return nilfs_attach_btree_node_cache(inode);
+}
+
+/**
+ * nilfs_remove_all_gcinodes() - remove all unprocessed gc inodes
+ * @nilfs: NILFS filesystem instance
+ */
+void nilfs_remove_all_gcinodes(struct the_nilfs *nilfs)
+{
+	struct list_head *head = &nilfs->ns_gc_inodes;
+	struct nilfs_inode_info *ii;
+
+	while (!list_empty(head)) {
+		ii = list_first_entry(head, struct nilfs_inode_info, i_dirty);
+		list_del_init(&ii->i_dirty);
+		truncate_inode_pages(&ii->vfs_inode.i_data, 0);
+		nilfs_btnode_cache_clear(ii->i_assoc_inode->i_mapping);
+		iput(&ii->vfs_inode);
+	}
+}