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

[Edward Adam Davis]

debug

#syz test: upstream c0ecd6388360

diff --git a/fs/file_table.c b/fs/file_table.c
index ca7843dde56d..3d7a59961ff6 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -418,6 +418,7 @@ static void __fput(struct file *file)
 		if (file->f_op->fasync)
 			file->f_op->fasync(-1, file, 0);
 	}
+	printk("ino: %lx, %s\n", inode->i_ino, __func__);
 	if (file->f_op->release)
 		file->f_op->release(inode, file);
 	if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index de009a33e0e2..7a08750da902 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: %p, inode fid list is empty: %d, %s\n", inode, 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)) {
@@ -132,8 +133,10 @@ static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
 		}
 		spin_unlock(&dentry->d_lock);
 	} else {
-		if (dentry->d_inode)
+		if (dentry->d_inode) {
+			printk("ino: %lx, %s\n", dentry->d_inode->i_ino, __func__);
 			ret = v9fs_fid_find_inode(dentry->d_inode, false, uid, any);
+		}
 	}
 
 	return ret;
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index a97ceb105cd8..a022263265fd 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",
@@ -105,6 +106,7 @@ static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
 			goto no_fid;
 		p9_fid_get(fid);
 	} else {
+		printk("ino: %lx, %s\n", rreq->inode->i_ino, __func__);
 		fid = v9fs_fid_find_inode(rreq->inode, writing, INVALID_UID, true);
 		if (!fid)
 			goto no_fid;
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index e0d34e4e9076..cf7200ed2553 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -218,6 +218,7 @@ 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: %lu, %s\n", inode, inode->i_ino,  __func__);
 		spin_lock(&inode->i_lock);
 		hlist_del(&fid->ilist);
 		spin_unlock(&inode->i_lock);
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 348cc90bf9c5..abadf3b5fecb 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("1ind: %p, file: %p, %s\n", inode, file,  __func__);
 	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
 	v9ses = v9fs_inode2v9ses(inode);
 	if (v9fs_proto_dotl(v9ses))
@@ -54,8 +55,10 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 	fid = file->private_data;
 	if (!fid) {
 		fid = v9fs_fid_clone(file_dentry(file));
-		if (IS_ERR(fid))
-			return PTR_ERR(fid);
+		if (IS_ERR(fid)) {
+			err = PTR_ERR(fid);
+			goto error;
+		}
 
 		if ((v9ses->cache & CACHE_WRITEBACK) && (omode & P9_OWRITE)) {
 			int writeback_omode = (omode & ~P9_OWRITE) | P9_ORDWR;
@@ -72,7 +75,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 		}
 		if (err < 0) {
 			p9_fid_put(fid);
-			return err;
+			goto error;
 		}
 		if ((file->f_flags & O_APPEND) &&
 			(!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)))
@@ -87,8 +90,13 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 				   file->f_mode & FMODE_WRITE);
 #endif
 	v9fs_fid_add_modes(fid, v9ses->flags, v9ses->cache, file->f_flags);
+	printk("2ind: %p, ino: %lu, %s\n", inode, inode->i_ino,  __func__);
 	v9fs_open_fid_add(inode, &fid);
 	return 0;
+error:
+	printk("err: %d, ind: %p, %s\n", err, inode, __func__);
+	return err;
+
 }
 
 /**
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index c61b97bd13b9..085a788a3262 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -284,9 +284,11 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 	}
 #endif
 	v9fs_fid_add_modes(ofid, v9ses->flags, v9ses->cache, flags);
+	printk("2ind: %p, ino: %lu, %s\n", inode, inode->i_ino,  __func__);
 	v9fs_open_fid_add(inode, &ofid);
 	file->f_mode |= FMODE_CREATED;
 out:
+	printk("err: %d, ind: %p, ino: %lu, %s\n", err, inode, inode->i_ino, __func__);
 	p9_fid_put(dfid);
 	p9_fid_put(ofid);
 	p9_fid_put(fid);