STRUCT FUSE_FILE(9)

💖 struct fuse_file(9) 💖

okay bestie, so we're deep in the Kernel API Manual today — like, kernel-internals deep — and this one is all about struct fuse_file, which is literally just the FUSE-specific file data. that's it, that's the vibe. it's the little bundle of bookkeeping that hangs off a file in FUSE-land. 🦋

✨ SYNOPSIS ✨

like, here's the whole shape of it, no notes:

struct fuse_file {
    struct fuse_mount *fm;
    union fuse_file_args *args;
    u64 kh;
    u64 fh;
    u64 nodeid;
    refcount_t count;
    u32 open_flags;
    struct list_head write_entry;
    struct {
      loff_t pos;
      loff_t cache_off;
      u64 version;
    } readdir;
    struct rb_node polled_node;
    wait_queue_head_t poll_wait;
    enum {
      IOM_NONE,
      IOM_CACHED,
    IOM_UNCACHED } iomode;
  #ifdef CONFIG_FUSE_PASSTHROUGH;
    struct file *passthrough;
    const struct cred *cred;
  #endif;
    bool flock:1;
 };

she's giving "small struct, big responsibilities" honestly 🎀

🌸 Members 🌸

so here's the rundown on every single field, because we do NOT skip fields in this house:

• fm — the fuse connection that this file belongs to. like, who's your mount, bestie?
• args — argument space that's reserved for open/release. reserved! as in, don't touch, it's saved for later 💅
• kh — the kernel file handle, and ngl it's guaranteed to be unique. iconic behavior.
• fh — the file handle that userspace actually uses. different from kh, don't mix them up 🙈
• nodeid — the node id of this file. it's literally its little name tag.
• count — the refcount. the way that refcount goes up and down... main character energy fr fr
• open_flags — the FOPEN_* flags that came back from open.
• write_entry — entry sitting on the inode's write_files list. that's the whole description, no cap.
• readdir — everything readdir-related. she's a little struct of her own with pos, cache_off, and version inside.
• polled_node — an RB node that gets linked onto fuse_conn->polled_files.
• poll_wait — the wait queue head for poll. yes, poll. we love a wait queue 💜
• iomode — does this file hold a fi->iocachectr refcount? that's the question, and IOM_NONE, IOM_CACHED, IOM_UNCACHED are the answers 🫶
• passthrough — a reference to the backing file when you're in passthrough mode. (only a thing under CONFIG_FUSE_PASSTHROUGH, iykyk)
• cred — the passthrough file credentials. also a CONFIG_FUSE_PASSTHROUGH girlie.
• flock — has flock even been performed on this file? bool bitfield, one bit, huge consequences ✨

🔥 SEE ALSO 🔥

okay so if you're going down the rabbit hole (and you will), the kernel file to go look at is ./fs/fuse/fuse_i.h, and the friends you'll bump into are:

• struct fuse_submount_lookup(9)
• struct fuse_inode(9)
• struct fuse_conn(9)
• fuse_fill_super_common(9)
• fuse_mount_remove(9)
• fuse_ctl_add_conn(9)
• fuse_ctl_remove_conn(9)

okay that's genuinely all of it — every field, every flag, nothing skipped, periodt. 💅

and for the cute little sign-off: this page lives over at ./fs/fuse and it's dated October 2026, so like... future vibes only, bestie. go read the source, ily, bye! 🎀💖🌸