[PATCH 11/19] fuse2fs: implement dirsync mode

Darrick J. Wong
2025-11-06T22:34:00Z

Implement dirsync so that we only perform full metadata flushes on
directory updates when the sysadmin explicitly wants it.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
misc/fuse2fs.1.in | 3 +
misc/fuse2fs.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 102 insertions(+), 12 deletions(-)

diff --git a/misc/fuse2fs.1.in b/misc/fuse2fs.1.in
index 69fc6b01d7b639..b18b7f3464bc74 100644
--- a/misc/fuse2fs.1.in
+++ b/misc/fuse2fs.1.in
@@ -57,6 +57,9 @@ .SS "fuse2fs options:"
\fB-o\fR direct
Use O_DIRECT to access the block device.
.TP
+\fB-o\fR dirsync
+Flush dirty metadata to disk after every directory update.
+.TP
\fB-o\fR errors=panic
dump core on error
.TP
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 16492d54f7ed1d..0b4f7f10ddc97f 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -232,6 +232,7 @@ struct fuse2fs {
int kernel;
int directio;
int acl;
+ int dirsync;

int logfd;
int blocklog;
@@ -1367,6 +1368,41 @@ static int fuse2fs_new_child_gid(struct fuse2fs *ff, ext2_ino_t parent,
return 0;
}

+/*
+ * Flush dirty data to disk if we're running in dirsync mode. If @flushed is a
+ * non-null pointer, this function sets @flushed to 1 if we decided to flush
+ * data, or 0 if not.
+ */
+static inline int fuse2fs_dirsync_flush(struct fuse2fs *ff, ext2_ino_t ino,
+ int *flushed)
+{
+ struct ext2_inode_large inode;
+ ext2_filsys fs = ff->fs;
+ errcode_t err;
+
+ if (ff->dirsync)
+ goto flush;
+
+ err = fuse2fs_read_inode(fs, ino, &inode);
+ if (err)
+ return translate_error(fs, 0, err);
+
+ if (inode.i_flags & EXT2_DIRSYNC_FL)
+ goto flush;
+
+ if (flushed)
+ *flushed = 0;
+ return 0;
+flush:
+ err = ext2fs_flush2(fs, 0);
+ if (err)
+ return translate_error(fs, 0, err);
+
+ if (flushed)
+ *flushed = 1;
+ return 0;
+}
+
static int op_mknod(const char *path, mode_t mode, dev_t dev)
{
struct fuse_context *ctxt = fuse_get_context();
@@ -1486,6 +1522,11 @@ static int op_mknod(const char *path, mode_t mode, dev_t dev)
ret = propagate_default_acls(ff, parent, child, inode.i_mode);
if (ret)
goto out2;
+
+ ret = fuse2fs_dirsync_flush(ff, parent, NULL);
+ if (ret)
+ goto out2;
+
out2:
pthread_mutex_unlock(&ff->bfl);
out:
@@ -1615,6 +1656,10 @@ static int op_mkdir(const char *path, mode_t mode)
if (ret)
goto out3;

+ ret = fuse2fs_dirsync_flush(ff, parent, NULL);
+ if (ret)
+ goto out3;
+
out3:
ext2fs_free_mem(&block);
out2:
@@ -1624,7 +1669,8 @@ static int op_mkdir(const char *path, mode_t mode)
return ret;
}

-static int unlink_file_by_name(struct fuse2fs *ff, const char *path)
+static int fuse2fs_unlink(struct fuse2fs *ff, const char *path,
+ ext2_ino_t *parent)
{
ext2_filsys fs = ff->fs;
errcode_t err;
@@ -1660,7 +1706,13 @@ static int unlink_file_by_name(struct fuse2fs *ff, const char *path)
if (err)
return translate_error(fs, dir, err);

- return update_mtime(fs, dir, NULL);
+ ret = update_mtime(fs, dir, NULL);
+ if (ret)
+ return ret;
+
+ if (parent)
+ *parent = dir;
+ return 0;
}

static int remove_ea_inodes(struct fuse2fs *ff, ext2_ino_t ino,
@@ -1772,7 +1824,7 @@ static int remove_inode(struct fuse2fs *ff, ext2_ino_t ino)
static int __op_unlink(struct fuse2fs *ff, const char *path)
{
ext2_filsys fs = ff->fs;
- ext2_ino_t ino;
+ ext2_ino_t parent, ino;
errcode_t err;
int ret = 0;

@@ -1786,13 +1838,18 @@ static int __op_unlink(struct fuse2fs *ff, const char *path)
if (ret)
goto out;

- ret = unlink_file_by_name(ff, path);
+ ret = fuse2fs_unlink(ff, path, &parent);
if (ret)
goto out;

ret = remove_inode(ff, ino);
if (ret)
goto out;
+
+ ret = fuse2fs_dirsync_flush(ff, parent, NULL);
+ if (ret)
+ goto out;
+
out:
return ret;
}
@@ -1841,7 +1898,7 @@ static int rmdir_proc(ext2_ino_t dir EXT2FS_ATTR((unused)),
static int __op_rmdir(struct fuse2fs *ff, const char *path)
{
ext2_filsys fs = ff->fs;
- ext2_ino_t child;
+ ext2_ino_t parent, child;
errcode_t err;
struct ext2_inode_large inode;
struct rd_struct rds;
@@ -1882,7 +1939,7 @@ static int __op_rmdir(struct fuse2fs *ff, const char *path)
goto out;
}

- ret = unlink_file_by_name(ff, path);
+ ret = fuse2fs_unlink(ff, path, &parent);
if (ret)
goto out;
/* Directories have to be "removed" twice. */
@@ -1913,6 +1970,10 @@ static int __op_rmdir(struct fuse2fs *ff, const char *path)
}
}

+ ret = fuse2fs_dirsync_flush(ff, parent, NULL);
+ if (ret)
+ goto out;
+
out:
return ret;
}
@@ -2028,6 +2089,11 @@ static int op_symlink(const char *src, const char *dest)
ret = translate_error(fs, child, err);
goto out2;
}
+
+ ret = fuse2fs_dirsync_flush(ff, parent, NULL);
+ if (ret)
+ goto out2;
+
out2:
pthread_mutex_unlock(&ff->bfl);
out:
@@ -2073,6 +2139,7 @@ static int op_rename(const char *from, const char *to
char *cp, a;
struct ext2_inode inode;
struct update_dotdot ud;
+ int flushed = 0;
int ret = 0;

#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 0)
@@ -2276,14 +2343,19 @@ static int op_rename(const char *from, const char *to
goto out2;

/* Remove the old file */
- ret = unlink_file_by_name(ff, from);
+ ret = fuse2fs_unlink(ff, from, NULL);
if (ret)
goto out2;

- /* Flush the whole mess out */
- err = ext2fs_flush2(fs, 0);
- if (err)
- ret = translate_error(fs, 0, err);
+ ret = fuse2fs_dirsync_flush(ff, from_dir_ino, &flushed);
+ if (ret)
+ goto out2;
+
+ if (from_dir_ino != to_dir_ino && !flushed) {
+ ret = fuse2fs_dirsync_flush(ff, to_dir_ino, NULL);
+ if (ret)
+ goto out2;
+ }

out2:
free(temp_from);
@@ -2380,6 +2452,10 @@ static int op_link(const char *src, const char *dest)
if (ret)
goto out2;

+ ret = fuse2fs_dirsync_flush(ff, parent, NULL);
+ if (ret)
+ goto out2;
+
out2:
pthread_mutex_unlock(&ff->bfl);
out:
@@ -3722,6 +3798,11 @@ static int op_create(const char *path, mode_t mode, struct fuse_file_info *fp)
ret = __op_open(ff, path, fp);
if (ret)
goto out2;
+
+ ret = fuse2fs_dirsync_flush(ff, parent, NULL);
+ if (ret)
+ goto out2;
+
out2:
pthread_mutex_unlock(&ff->bfl);
out:
@@ -4661,6 +4742,7 @@ enum {
FUSE2FS_HELP,
FUSE2FS_HELPFULL,
FUSE2FS_CACHE_SIZE,
+ FUSE2FS_DIRSYNC,
};

#define FUSE2FS_OPT(t, p, v) { t, offsetof(struct fuse2fs, p), v }
@@ -4681,12 +4763,13 @@ static struct fuse_opt fuse2fs_opts[] = {
FUSE2FS_OPT("directio", directio, 1),
FUSE2FS_OPT("acl", acl, 1),
FUSE2FS_OPT("noacl", acl, 0),
+ FUSE2FS_OPT("lockfile=%s", lockfile, 0),

FUSE_OPT_KEY("user_xattr", FUSE2FS_IGNORED),
FUSE_OPT_KEY("noblock_validity", FUSE2FS_IGNORED),
FUSE_OPT_KEY("nodelalloc", FUSE2FS_IGNORED),
FUSE_OPT_KEY("cache_size=%s", FUSE2FS_CACHE_SIZE),
- FUSE2FS_OPT("lockfile=%s", lockfile, 0),
+ FUSE_OPT_KEY("dirsync", FUSE2FS_DIRSYNC),

FUSE_OPT_KEY("-V", FUSE2FS_VERSION),
FUSE_OPT_KEY("--version", FUSE2FS_VERSION),
@@ -4703,6 +4786,10 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
struct fuse2fs *ff = data;

switch (key) {
+ case FUSE2FS_DIRSYNC:
+ ff->dirsync = 1;
+ /* pass through to libfuse */
+ return 1;
case FUSE_OPT_KEY_NONOPT:
if (!ff->device) {
ff->device = strdup(arg);