[PATCH 10/10] fuse2fs: set sync, immutable, and append at file load time

Darrick J. Wong
2025-09-16T01:06:03Z

Convey these three inode flags to the kernel when we're loading a file.
This way the kernel can advertise and enforce those flags so that the
fuse server doesn't have to.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
fuse4fs/fuse4fs.c | 10 ++++++++++
misc/fuse2fs.c | 53 ++++++++++++++++++++++++++++++++++++++---------------
2 files changed, 48 insertions(+), 15 deletions(-)

diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index 4f5618e64a93c3..a7709a7e6fb699 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -1800,6 +1800,16 @@ static int fuse4fs_stat_inode(struct fuse4fs *ff, ext2_ino_t ino,
entry->entry_timeout = FUSE4FS_ATTR_TIMEOUT;

fstat->iflags = 0;
+
+ if (inodep->i_flags & EXT2_SYNC_FL)
+ fstat->iflags |= FUSE_IFLAG_SYNC;
+
+ if (inodep->i_flags & EXT2_IMMUTABLE_FL)
+ fstat->iflags |= FUSE_IFLAG_IMMUTABLE;
+
+ if (inodep->i_flags & EXT2_APPEND_FL)
+ fstat->iflags |= FUSE_IFLAG_APPEND;
+
#ifdef HAVE_FUSE_IOMAP
if (fuse4fs_iomap_enabled(ff)) {
fstat->iflags |= FUSE_IFLAG_IOMAP;
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index b193e0b2c06b69..260d1b77e3f24b 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1584,7 +1584,7 @@ static void *op_init(struct fuse_conn_info *conn,
}

static int fuse2fs_stat(struct fuse2fs *ff, ext2_ino_t ino,
- struct stat *statbuf)
+ struct stat *statbuf, unsigned int *iflags)
{
struct ext2_inode_large inode;
ext2_filsys fs = ff->fs;
@@ -1641,6 +1641,7 @@ static int fuse2fs_stat(struct fuse2fs *ff, ext2_ino_t ino,
statbuf->st_rdev = inode.i_block[1];
}

+ *iflags = inode.i_flags;
return ret;
}

@@ -1675,22 +1676,31 @@ static int __fuse2fs_file_ino(struct fuse2fs *ff, const char *path,
# define fuse2fs_file_ino(ff, path, fp, inop) \
__fuse2fs_file_ino((ff), (path), (fp), (inop), __func__, __LINE__)

+static int fuse2fs_getattr(struct fuse2fs *ff, const char *path,
+ struct stat *statbuf, struct fuse_file_info *fi,
+ unsigned int *iflags)
+{
+ ext2_ino_t ino;
+ int ret = 0;
+
+ FUSE2FS_CHECK_CONTEXT(ff);
+ fuse2fs_start(ff);
+ ret = fuse2fs_file_ino(ff, path, fi, &ino);
+ if (ret)
+ goto out;
+ ret = fuse2fs_stat(ff, ino, statbuf, iflags);
+out:
+ fuse2fs_finish(ff, ret);
+ return ret;
+}
+
static int op_getattr(const char *path, struct stat *statbuf,
struct fuse_file_info *fi)
{
struct fuse2fs *ff = fuse2fs_get();
- ext2_ino_t ino;
- int ret = 0;
+ unsigned int dontcare;

- FUSE2FS_CHECK_CONTEXT(ff);
- fuse2fs_start(ff);
- ret = fuse2fs_file_ino(ff, path, fi, &ino);
- if (ret)
- goto out;
- ret = fuse2fs_stat(ff, ino, statbuf);
-out:
- fuse2fs_finish(ff, ret);
- return ret;
+ return fuse2fs_getattr(ff, path, statbuf, fi, &dontcare);
}

#if FUSE_VERSION >= FUSE_MAKE_VERSION(3, 99)
@@ -1698,11 +1708,21 @@ static int op_getattr_iflags(const char *path, struct stat *statbuf,
unsigned int *iflags, struct fuse_file_info *fi)
{
struct fuse2fs *ff = fuse2fs_get();
- int ret = op_getattr(path, statbuf, fi);
+ unsigned int i_flags;
+ int ret = fuse2fs_getattr(ff, path, statbuf, fi, &i_flags);

if (ret)
return ret;

+ if (i_flags & EXT2_IMMUTABLE_FL)
+ *iflags |= FUSE_IFLAG_IMMUTABLE;
+
+ if (i_flags & EXT2_SYNC_FL)
+ *iflags |= FUSE_IFLAG_SYNC;
+
+ if (i_flags & EXT2_APPEND_FL)
+ *iflags |= FUSE_IFLAG_APPEND;
+
if (fuse_fs_can_enable_iomap(statbuf)) {
*iflags |= FUSE_IFLAG_IOMAP;

@@ -3415,12 +3435,13 @@ static int fuse2fs_punch_posteof(struct fuse2fs *ff, ext2_ino_t ino,
static int fuse2fs_file_uses_iomap(struct fuse2fs *ff, ext2_ino_t ino)
{
struct stat statbuf;
+ unsigned int dontcare;
int ret;

if (!fuse2fs_iomap_enabled(ff))
return 0;

- ret = fuse2fs_stat(ff, ino, &statbuf);
+ ret = fuse2fs_stat(ff, ino, &statbuf, &dontcare);
if (ret)
return ret;

@@ -4322,7 +4343,9 @@ static int op_readdir_iter(ext2_ino_t dir EXT2FS_ATTR((unused)),
(unsigned long long)i->dirpos);

if (i->flags == FUSE_READDIR_PLUS) {
- ret = fuse2fs_stat(i->ff, dirent->inode, &stat);
+ unsigned int dontcare;
+
+ ret = fuse2fs_stat(i->ff, dirent->inode, &stat, &dontcare);
if (ret)
return DIRENT_ABORT;
}