linux-ext4 - [PATCH 3/3] fuse2fs: enable the shutdown ioctl

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Message-ID: <175798065210.350393.10163706639168342705.stgit@frogsfrogsfrogs>
Date: Mon, 15 Sep 2025 17:05:35 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 3/3] fuse2fs: enable the shutdown ioctl

From: Darrick J. Wong <djwong@...nel.org>

Implement a bastardized version of EXT4_IOC_SHUTDOWN, because the people
who invented the ioctl got the direction wrong, so we can't actually
read the flags.

Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
 misc/fuse2fs.c |   42 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 4 deletions(-)


diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 80d1c79b5cce1c..101f0fa03c397d 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -221,6 +221,7 @@ struct fuse2fs_file_handle {
 enum fuse2fs_opstate {
 	F2OP_READONLY,
 	F2OP_WRITABLE,
+	F2OP_SHUTDOWN,
 };
 
 /* Main program context */
@@ -276,7 +277,7 @@ struct fuse2fs {
 		} \
 	} while (0)
 
-#define __FUSE2FS_CHECK_CONTEXT(ff, retcode) \
+#define __FUSE2FS_CHECK_CONTEXT(ff, retcode, shutcode) \
 	do { \
 		if ((ff) == NULL || (ff)->magic != FUSE2FS_MAGIC) { \
 			fprintf(stderr, \
@@ -285,14 +286,17 @@ struct fuse2fs {
 			fflush(stderr); \
 			retcode; \
 		} \
+		if ((ff)->opstate == F2OP_SHUTDOWN) { \
+			shutcode; \
+		} \
 	} while (0)
 
 #define FUSE2FS_CHECK_CONTEXT(ff) \
-	__FUSE2FS_CHECK_CONTEXT((ff), return -EUCLEAN)
+	__FUSE2FS_CHECK_CONTEXT((ff), return -EUCLEAN, return -EIO)
 #define FUSE2FS_CHECK_CONTEXT_RETURN(ff) \
-	__FUSE2FS_CHECK_CONTEXT((ff), return)
+	__FUSE2FS_CHECK_CONTEXT((ff), return, return)
 #define FUSE2FS_CHECK_CONTEXT_ABORT(ff) \
-	__FUSE2FS_CHECK_CONTEXT((ff), abort())
+	__FUSE2FS_CHECK_CONTEXT((ff), abort(), abort())
 
 static int __translate_error(ext2_filsys fs, ext2_ino_t ino, errcode_t err,
 			     const char *func, int line);
@@ -4566,6 +4570,33 @@ static int ioctl_fitrim(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
 }
 #endif /* FITRIM */
 
+#ifndef EXT4_IOC_SHUTDOWN
+# define EXT4_IOC_SHUTDOWN	_IOR('X', 125, __u32)
+#endif
+
+static int ioctl_shutdown(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
+			  void *data)
+{
+	struct fuse_context *ctxt = fuse_get_context();
+	ext2_filsys fs = ff->fs;
+
+	if (!is_superuser(ff, ctxt))
+		return -EPERM;
+
+	err_printf(ff, "%s.\n", _("shut down requested"));
+
+	/*
+	 * EXT4_IOC_SHUTDOWN inherited the inverted polarity on the ioctl
+	 * direction from XFS.  Unfortunately, that means we can't implement
+	 * any of the flags.  Flush whatever is dirty and shut down.
+	 */
+	if (ff->opstate == F2OP_WRITABLE)
+		ext2fs_flush2(fs, 0);
+	ff->opstate = F2OP_SHUTDOWN;
+
+	return 0;
+}
+
 #if FUSE_VERSION >= FUSE_MAKE_VERSION(2, 8)
 static int op_ioctl(const char *path EXT2FS_ATTR((unused)),
 #if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 0)
@@ -4612,6 +4643,9 @@ static int op_ioctl(const char *path EXT2FS_ATTR((unused)),
 		ret = ioctl_fitrim(ff, fh, data);
 		break;
 #endif
+	case EXT4_IOC_SHUTDOWN:
+		ret = ioctl_shutdown(ff, fh, data);
+		break;
 	default:
 		dbg_printf(ff, "%s: Unknown ioctl %d\n", __func__, cmd);
 		ret = -ENOTTY;