Re: [syzbot] [v9fs?] WARNING in v9fs_begin_writeback

[Edward Adam Davis]

debug

#syz test: upstream c0ecd6388360

diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index de009a33e0e2..d008ae949047 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -67,6 +67,7 @@ struct p9_fid *v9fs_fid_find_inode(struct inode *inode, bool want_writeable,
 
 	spin_lock(&inode->i_lock);
 	h = (struct hlist_head *)&inode->i_private;
+	printk("ino: %lx, inode fid list is empty: %d, %s\n", inode->i_ino, hlist_empty(h), __func__);
 	hlist_for_each_entry(fid, h, ilist) {
 		if (any || uid_eq(fid->uid, uid)) {
 			if (want_writeable && !v9fs_is_writeable(fid->mode)) {
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index a97ceb105cd8..7768cc70439d 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -34,6 +34,7 @@ static void v9fs_begin_writeback(struct netfs_io_request *wreq)
 {
 	struct p9_fid *fid;
 
+	printk("ino: %lx, %s\n", wreq->inode->i_ino, __func__);
 	fid = v9fs_fid_find_inode(wreq->inode, true, INVALID_UID, true);
 	if (!fid) {
 		WARN_ONCE(1, "folio expected an open fid inode->i_ino=%lx\n",
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index e0d34e4e9076..4f02d8f294b1 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -218,7 +218,12 @@ int v9fs_dir_release(struct inode *inode, struct file *filp)
 		if ((S_ISREG(inode->i_mode)) && (filp->f_mode & FMODE_WRITE))
 			retval = filemap_fdatawrite(inode->i_mapping);
 
+		printk("del, ind: %p, ino: %lx, %s\n", inode, inode->i_ino,  __func__);
 		spin_lock(&inode->i_lock);
+		if (inode_is_dirtytime_only(inode)) {
+			spin_unlock(&inode->i_lock);
+			return -EINVAL;
+		}
 		hlist_del(&fid->ilist);
 		spin_unlock(&inode->i_lock);
 		put_err = p9_fid_put(fid);
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 348cc90bf9c5..b0c2cd989854 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -44,6 +44,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 	struct p9_fid *fid;
 	int omode;
 
+	printk("ind: %p, ino: %lx, %s\n", inode, inode->i_ino,  __func__);
 	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
 	v9ses = v9fs_inode2v9ses(inode);
 	if (v9fs_proto_dotl(v9ses))