[Concept,32/34] fs: Add ext4 VFS driver

Message ID 20260403140523.1998228-33-sjg@u-boot.org
State New
Headers
Series Add a virtual filesystem (VFS) layer to U-Boot |

Commit Message

Simon Glass April 3, 2026, 2:04 p.m. UTC
  From: Simon Glass <sjg@chromium.org>

Add a UCLASS_FS driver for the old ext4 filesystem implementation,
allowing it to be mounted through the VFS layer. The driver wraps the
existing ext4fs functions for mount, unmount, directory listing, file
read/write, unlink and symlink creation. Write operations are guarded
by CONFIG_EXT4_WRITE.

This complements the ext4l VFS driver, enabling VFS on boards that use
the original ext4 implementation.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

 fs/ext4/Makefile |   1 +
 fs/ext4/fs.c     | 264 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 265 insertions(+)
 create mode 100644 fs/ext4/fs.c
  

Patch

diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 6ae44a2d0a3..f79baccc6a7 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -9,3 +9,4 @@ 
 
 obj-y := ext4fs.o ext4_common.o dev.o
 obj-$(CONFIG_EXT4_WRITE) += ext4_write.o ext4_journal.o
+obj-$(CONFIG_$(PHASE_)VFS) += fs.o
diff --git a/fs/ext4/fs.c b/fs/ext4/fs.c
new file mode 100644
index 00000000000..09cbddee50f
--- /dev/null
+++ b/fs/ext4/fs.c
@@ -0,0 +1,264 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ext4 filesystem driver for the VFS layer
+ *
+ * Wraps the existing ext4 implementation to provide UCLASS_FS and
+ * UCLASS_DIR devices, following the same pattern as the FAT VFS driver.
+ *
+ * Copyright 2026 Simon Glass <sjg@chromium.org>
+ */
+
+#define LOG_CATEGORY	UCLASS_FS
+
+#include <blk.h>
+#include <dir.h>
+#include <dm.h>
+#include <ext4fs.h>
+#include <file.h>
+#include <fs.h>
+#include <iovec.h>
+#include <malloc.h>
+#include <vfs.h>
+#include <dm/device-internal.h>
+
+/**
+ * struct ext4_dir_priv - Private info for ext4 directory devices
+ *
+ * @strm: Directory stream from ext4fs_opendir(), or NULL
+ */
+struct ext4_dir_priv {
+	struct fs_dir_stream *strm;
+};
+
+static int ext4_vfs_mount(struct udevice *dev)
+{
+	struct fs_priv *uc_priv = dev_get_uclass_priv(dev);
+	struct fs_plat *plat = dev_get_uclass_plat(dev);
+	int ret;
+
+	if (uc_priv->mounted)
+		return log_msg_ret("emm", -EISCONN);
+
+	if (!plat->desc)
+		return log_msg_ret("emd", -ENODEV);
+
+	ret = ext4fs_probe(plat->desc, &plat->part);
+	if (ret)
+		return log_msg_ret("emp", ret);
+
+	uc_priv->mounted = true;
+
+	return 0;
+}
+
+static int ext4_vfs_unmount(struct udevice *dev)
+{
+	struct fs_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (!uc_priv->mounted)
+		return log_msg_ret("euu", -ENOTCONN);
+
+	ext4fs_close();
+	uc_priv->mounted = false;
+
+	return 0;
+}
+
+static int ext4_vfs_lookup_dir(struct udevice *dev, const char *path,
+			       struct udevice **dirp)
+{
+	struct udevice *dir;
+	int ret;
+
+	ret = dir_add_probe(dev, DM_DRIVER_GET(ext4_vfs_dir), path, &dir);
+	if (ret)
+		return log_msg_ret("eld", ret);
+
+	*dirp = dir;
+
+	return 0;
+}
+
+#if IS_ENABLED(CONFIG_EXT4_WRITE)
+static int ext4_vfs_unlink(struct udevice *dev, const char *path)
+{
+	return ext4fs_filename_unlink((char *)path);
+}
+
+static int ext4_vfs_ln(struct udevice *dev, const char *path,
+		       const char *target)
+{
+	return ext4fs_create_link(target, path);
+}
+#endif
+
+static const struct fs_ops ext4_vfs_ops = {
+	.mount		= ext4_vfs_mount,
+	.unmount	= ext4_vfs_unmount,
+	.lookup_dir	= ext4_vfs_lookup_dir,
+#if IS_ENABLED(CONFIG_EXT4_WRITE)
+	.unlink		= ext4_vfs_unlink,
+	.ln		= ext4_vfs_ln,
+#endif
+};
+
+U_BOOT_DRIVER(ext4_old_fs) = {
+	.name	= "ext4_old_fs",
+	.id	= UCLASS_FS,
+	.ops	= &ext4_vfs_ops,
+};
+
+/* ext4 directory driver */
+
+static int ext4_dir_open(struct udevice *dev, struct fs_dir_stream *strm)
+{
+	struct ext4_dir_priv *priv = dev_get_priv(dev);
+	struct dir_uc_priv *uc_priv = dev_get_uclass_priv(dev);
+	struct fs_dir_stream *ext4_strm;
+	const char *path;
+	int ret;
+
+	path = *uc_priv->path ? uc_priv->path : "/";
+	ret = ext4fs_opendir(path, &ext4_strm);
+	if (ret)
+		return log_msg_ret("edo", ret);
+
+	priv->strm = ext4_strm;
+
+	return 0;
+}
+
+static int ext4_dir_read(struct udevice *dev, struct fs_dir_stream *strm,
+			 struct fs_dirent *dent)
+{
+	struct ext4_dir_priv *priv = dev_get_priv(dev);
+	struct fs_dirent *ext4_dent;
+	int ret;
+
+	ret = ext4fs_readdir(priv->strm, &ext4_dent);
+	if (ret)
+		return ret;
+
+	*dent = *ext4_dent;
+
+	return 0;
+}
+
+static int ext4_dir_close(struct udevice *dev, struct fs_dir_stream *strm)
+{
+	struct ext4_dir_priv *priv = dev_get_priv(dev);
+
+	ext4fs_closedir(priv->strm);
+	priv->strm = NULL;
+
+	return 0;
+}
+
+/* ext4 file driver */
+
+/**
+ * struct ext4_file_priv - Private info for ext4 file devices
+ *
+ * @path: Full path within the ext4 filesystem
+ */
+struct ext4_file_priv {
+	char path[FILE_MAX_PATH_LEN];
+};
+
+static ssize_t ext4_read_iter(struct udevice *dev, struct iov_iter *iter,
+			      loff_t pos)
+{
+	struct ext4_file_priv *priv = dev_get_priv(dev);
+	loff_t actual;
+	int ret;
+
+	ret = ext4_read_file(priv->path, iter_iov_ptr(iter), pos,
+			     iter_iov_avail(iter), &actual);
+	if (ret)
+		return log_msg_ret("efr", ret);
+	iter_advance(iter, actual);
+
+	return actual;
+}
+
+#if IS_ENABLED(CONFIG_EXT4_WRITE)
+static ssize_t ext4_write_iter(struct udevice *dev, struct iov_iter *iter,
+			       loff_t pos)
+{
+	struct ext4_file_priv *priv = dev_get_priv(dev);
+	loff_t actual;
+	int ret;
+
+	ret = ext4_write_file(priv->path, (void *)iter_iov_ptr(iter), pos,
+			      iter_iov_avail(iter), &actual);
+	if (ret)
+		return log_msg_ret("efw", ret);
+	iter_advance(iter, actual);
+
+	return actual;
+}
+#endif
+
+static struct file_ops ext4_file_ops = {
+	.read_iter	= ext4_read_iter,
+#if IS_ENABLED(CONFIG_EXT4_WRITE)
+	.write_iter	= ext4_write_iter,
+#endif
+};
+
+U_BOOT_DRIVER(ext4_vfs_file) = {
+	.name		= "ext4_vfs_file",
+	.id		= UCLASS_FILE,
+	.ops		= &ext4_file_ops,
+	.priv_auto	= sizeof(struct ext4_file_priv),
+};
+
+static int ext4_dir_open_file(struct udevice *dir, const char *leaf,
+			      enum dir_open_flags_t oflags,
+			      struct udevice **filp)
+{
+	struct dir_uc_priv *uc_priv = dev_get_uclass_priv(dir);
+	struct ext4_file_priv *priv;
+	struct udevice *dev;
+	char path[FILE_MAX_PATH_LEN];
+	loff_t size = 0;
+	int ret;
+
+	if (*uc_priv->path)
+		snprintf(path, sizeof(path), "%s/%s", uc_priv->path, leaf);
+	else
+		snprintf(path, sizeof(path), "/%s", leaf);
+
+	if (oflags == DIR_O_RDONLY) {
+		if (!ext4fs_exists(path))
+			return log_msg_ret("eoe", -ENOENT);
+		ret = ext4fs_size(path, &size);
+		if (ret)
+			return log_msg_ret("eos", ret);
+	}
+
+	ret = file_add_probe(dir, DM_DRIVER_REF(ext4_vfs_file), leaf,
+			     size, oflags, &dev);
+	if (ret)
+		return log_msg_ret("eop", ret);
+
+	priv = dev_get_priv(dev);
+	strlcpy(priv->path, path, sizeof(priv->path));
+	*filp = dev;
+
+	return 0;
+}
+
+static struct dir_ops ext4_dir_ops = {
+	.open		= ext4_dir_open,
+	.read		= ext4_dir_read,
+	.close		= ext4_dir_close,
+	.open_file	= ext4_dir_open_file,
+};
+
+U_BOOT_DRIVER(ext4_vfs_dir) = {
+	.name		= "ext4_vfs_dir",
+	.id		= UCLASS_DIR,
+	.ops		= &ext4_dir_ops,
+	.priv_auto	= sizeof(struct ext4_dir_priv),
+};