STRUCT V4L2_FILE_OPERATIONS(9)

💖 struct v4l2_file_operations(9) 💖

okay bestie, welcome to the Kernel API Manual page for struct v4l2_file_operations — and yes, this is literally the fs operations used by a V4L2 device, no cap. We're doing every member, every reference, zero crumbs left behind, periodt ✨

💖 NAME 💖

struct v4l2_file_operations — fs operations used by a V4L2 device. That's the whole name-vibe: this struct is the fs op set for a V4L2 device, and the kernel is lowkey counting on it 🫶

✨ SYNOPSIS ✨

here's the struct exactly as the manual serves it — same code, same spelling, same energy, don't let anyone "fix" it in the group chat 😭:

       struct v4l2_file_operations {
           struct module *owner;
           ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
           ssize_t (*write) (struct file *, const char __user *, size_t, loff_t
       *);
           __poll_t (*poll) (struct file *, struct poll_table_struct *);
           long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
         #ifdef CONFIG_COMPAT;
           long (*compat_ioctl32) (struct file *, unsigned int, unsigned long);
         #endif;
           unsigned long (*get_unmapped_area) (struct file *, unsigned long,
       unsigned long, unsigned long, unsigned long);
           int (*mmap) (struct file *, struct vm_area_struct *);
           int (*open) (struct file *);
           int (*release) (struct file *);
        };

🌸 Members 🌸

okay so every field is a little main character, and here's exactly what each one does:

• owner — pointer to struct module.
• read — operations needed to implement the read syscall.
• write — operations needed to implement the write syscall.
• poll — operations needed to implement the poll syscall.
• unlocked_ioctl — operations needed to implement the ioctl syscall.
• compat_ioctl32 — operations needed to implement the ioctl syscall for the special case where the Kernel uses 64 bits instructions, but the userspace uses 32 bits.
• get_unmapped_area — called by the mmap syscall, used when %!CONFIG_MMU.
• mmap — operations needed to implement the mmap syscall.
• open — operations needed to implement the open syscall.
• release — operations needed to implement the release syscall.

💅 Description 💅

⚠️ NOTE: those operations are used to implemente the fs struct file_operations at the V4L2 drivers. The V4L2 core overrides the fs ops with some extra logic needed by the subsystem — and yes, "implemente" is the original spelling, we're not editing the lore 💀.

🦋 SEE ALSO 🦋

bestie, the lore goes DEEP — every single reference from the manual, all present and accounted for 👑:

• Kernel file ./include/media/v4l2-dev.h
• enum vfl_devnode_type(9)
• enum vfl_devnode_direction(9)
• enum v4l2_video_device_flags(9)
• struct v4l2_prio_state(9)
• v4l2_prio_init(9)
• v4l2_prio_change(9)
• v4l2_prio_open(9)
• v4l2_prio_close(9)
• v4l2_prio_max(9)
• v4l2_prio_check(9)
• struct video_device(9)
• media_entity_to_video_device(9)
• to_video_device(9)
• __video_register_device(9)
• video_register_device(9)
• video_register_device_no_warn(9)
• video_unregister_device(9)
• video_device_alloc(9)
• video_device_release(9)
• video_device_release_empty(9)
• v4l2_disable_ioctl(9)
• video_get_drvdata(9)
• video_set_drvdata(9)
• video_devdata(9)
• video_drvdata(9)
• video_device_node_name(9)
• video_is_registered(9)
• v4l2_debugfs_root(9)
• video_device_pipeline_start(9)
• __video_device_pipeline_start(9)
• video_device_pipeline_stop(9)
• __video_device_pipeline_stop(9)
• video_device_pipeline_alloc_start(9)
• video_device_pipeline(9)

💜 sign-off: source ./include/media · date October 2026 · page struct v4l2_file_operations(9) — mwah, go be iconic with your fs ops bestie 🌈