Re: [PATCH 09/25] libfuse: add upper level iomap ioend commands

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Apr 29, 2026 at 07:41:25AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Teach the upper level fuse library about iomap ioend events, which
> happen when a write that isn't a pure overwrite completes.
> 
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  include/fuse.h |    9 +++++++++
>  lib/fuse.c     |   53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+)
> 
> 
> diff --git a/include/fuse.h b/include/fuse.h
> index 8e79103f45404d..dbb72c80b138c6 100644
> --- a/include/fuse.h
> +++ b/include/fuse.h
> @@ -902,6 +902,15 @@ struct fuse_operations {
>  			 off_t pos_in, uint64_t length_in,
>  			 uint32_t opflags_in, ssize_t written_in,
>  			 const struct fuse_file_iomap *iomap);
> +
> +	/**
> +	 * Respond to the outcome of a file IO operation.
> +	 */
> +	int (*iomap_ioend)(const char *path, uint64_t nodeid,
> +			   uint64_t attr_ino, off_t pos_in,
> +			   uint64_t written_in, uint32_t ioendflags_in,
> +			   int error_in, uint32_t dev_in,
> +			   uint64_t new_addr_in, off_t *newsize);
>  };
>  
>  /** Extra context that may be needed by some filesystems
> diff --git a/lib/fuse.c b/lib/fuse.c
> index 8f012710c994d5..1bd672a7818a1f 100644
> --- a/lib/fuse.c
> +++ b/lib/fuse.c
> @@ -2872,6 +2872,28 @@ int fuse_fs_iomap_device_remove(int device_id)
>  	return fuse_lowlevel_iomap_device_remove(se, device_id);
>  }
>  
> +static int fuse_fs_iomap_ioend(struct fuse_fs *fs, const char *path,
> +			       uint64_t nodeid, uint64_t attr_ino, off_t pos,
> +			       uint64_t written, uint32_t ioendflags, int error,
> +			       uint32_t dev, uint64_t new_addr, off_t *newsize)
> +{
> +	fuse_get_context()->private_data = fs->user_data;
> +	if (!fs->op.iomap_ioend)
> +		return -ENOSYS;
> +
> +	if (fs->debug) {
> +		fuse_log(FUSE_LOG_DEBUG,
> +			 "iomap_ioend[%s] nodeid %llu attr_ino %llu pos %llu written %zu ioendflags 0x%x error %d dev %u new_addr 0x%llx\n",
> +			 path, (unsigned long long)nodeid,
> +			 (unsigned long long)attr_ino, (unsigned long long)pos,
> +			 written, ioendflags, error, dev,
> +			 (unsigned long long)new_addr);
> +	}
> +
> +	return fs->op.iomap_ioend(path, nodeid, attr_ino, pos, written,
> +				  ioendflags, error, dev, new_addr, newsize);
> +}
> +
>  static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
>  			     int valid, struct fuse_file_info *fi)
>  {
> @@ -4621,6 +4643,36 @@ static void fuse_lib_iomap_end(fuse_req_t req, fuse_ino_t nodeid,
>  	reply_err(req, err);
>  }
>  
> +static void fuse_lib_iomap_ioend(fuse_req_t req, fuse_ino_t nodeid,
> +				 uint64_t attr_ino, off_t pos, size_t written,

Heh, Codex noticed this type mismatch -- this function declares @written
as size_t parameter, but then gets assigned to a function pointer
looking for a uint64_t parameter.

gcc didn't complain?  WTF.

--D

> +				 uint32_t ioendflags, int error, uint32_t dev,
> +				 uint64_t new_addr)
> +{
> +	struct fuse *f = req_fuse_prepare(req);
> +	struct fuse_intr_data d;
> +	char *path;
> +	off_t newsize = 0;
> +	int err;
> +
> +	err = get_path_nullok(f, nodeid, &path);
> +	if (err) {
> +		reply_err(req, err);
> +		return;
> +	}
> +
> +	fuse_prepare_interrupt(f, req, &d);
> +	err = fuse_fs_iomap_ioend(f->fs, path, nodeid, attr_ino, pos, written,
> +				  ioendflags, error, dev, new_addr, &newsize);
> +	fuse_finish_interrupt(f, req, &d);
> +	free_path(f, nodeid, path);
> +	if (err) {
> +		reply_err(req, err);
> +		return;
> +	}
> +
> +	fuse_reply_iomap_ioend(req, newsize);
> +}
> +
>  static int clean_delay(struct fuse *f)
>  {
>  	/*
> @@ -4725,6 +4777,7 @@ static struct fuse_lowlevel_ops fuse_path_ops = {
>  	.syncfs = fuse_lib_syncfs,
>  	.iomap_begin = fuse_lib_iomap_begin,
>  	.iomap_end = fuse_lib_iomap_end,
> +	.iomap_ioend = fuse_lib_iomap_ioend,
>  };
>  
>  int fuse_notify_poll(struct fuse_pollhandle *ph)
> 
>