linux-ext4 - [PATCH 13/29] fuse2fs: implement O

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Message-ID: <174786677783.1383760.5736479713431403960.stgit@frogsfrogsfrogs>
Date: Wed, 21 May 2025 15:38:18 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 13/29] fuse2fs: implement O_TRUNC correctly

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

Actually truncate files on open with O_TRUNC.

Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
 misc/fuse2fs.c |   56 +++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 33 insertions(+), 23 deletions(-)


diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 299e62d3935886..9e7d8b8fe5118d 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1950,6 +1950,29 @@ static int op_chown(const char *path, uid_t owner, gid_t group
 	return ret;
 }
 
+static int truncate_helper(ext2_filsys fs, ext2_ino_t ino, off_t new_size)
+{
+	ext2_file_t file;
+	errcode_t err;
+	int ret = 0;
+
+	err = ext2fs_file_open(fs, ino, EXT2_FILE_WRITE, &file);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = ext2fs_file_set_size2(file, new_size);
+	if (err)
+		ret = translate_error(fs, ino, err);
+
+	err = ext2fs_file_close(file);
+	if (ret)
+		return ret;
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return update_mtime(fs, ino, NULL);
+}
+
 static int op_truncate(const char *path, off_t len
 #if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 0)
 			, struct fuse_file_info *fi EXT2FS_ATTR((unused))
@@ -1959,9 +1982,8 @@ static int op_truncate(const char *path, off_t len
 	struct fuse_context *ctxt = fuse_get_context();
 	struct fuse2fs *ff = (struct fuse2fs *)ctxt->private_data;
 	ext2_filsys fs;
-	errcode_t err;
 	ext2_ino_t ino;
-	ext2_file_t file;
+	errcode_t err;
 	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
@@ -1982,28 +2004,9 @@ static int op_truncate(const char *path, off_t len
 	if (ret)
 		goto out;
 
-	err = ext2fs_file_open(fs, ino, EXT2_FILE_WRITE, &file);
-	if (err) {
-		ret = translate_error(fs, ino, err);
-		goto out;
-	}
-
-	err = ext2fs_file_set_size2(file, len);
-	if (err) {
-		ret = translate_error(fs, ino, err);
-		goto out2;
-	}
-
-out2:
-	err = ext2fs_file_close(file);
+	ret = truncate_helper(fs, ino, len);
 	if (ret)
 		goto out;
-	if (err) {
-		ret = translate_error(fs, ino, err);
-		goto out;
-	}
-
-	ret = update_mtime(fs, ino, NULL);
 
 out:
 	pthread_mutex_unlock(&ff->bfl);
@@ -2039,7 +2042,7 @@ static int __op_open(struct fuse2fs *ff, const char *path,
 	struct fuse2fs_file_handle *file;
 	int check = 0, ret = 0;
 
-	dbg_printf(ff, "%s: path=%s\n", __func__, path);
+	dbg_printf(ff, "%s: path=%s oflags=0o%o\n", __func__, path, fp->flags);
 	err = ext2fs_get_mem(sizeof(*file), &file);
 	if (err)
 		return translate_error(fs, 0, err);
@@ -2090,6 +2093,13 @@ static int __op_open(struct fuse2fs *ff, const char *path,
 		} else
 			goto out;
 	}
+
+	if (fp->flags & O_TRUNC) {
+		ret = truncate_helper(fs, file->ino, 0);
+		if (ret)
+			goto out;
+	}
+
 	fp->fh = (uintptr_t)file;
 
 out: