On Wed, May 21, 2025 at 5:03 PM Darrick J. Wong <djwong@xxxxxxxxxx> wrote:
>
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> Implement functions to enable upcalling of iomap_begin and iomap_end to
> userspace fuse servers.
>
> Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
> ---
> fs/fuse/fuse_i.h | 38 ++++++
> fs/fuse/fuse_trace.h | 258 +++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/fuse.h | 87 ++++++++++++++
> fs/fuse/Kconfig | 23 ++++
> fs/fuse/Makefile | 1
> fs/fuse/file_iomap.c | 280 +++++++++++++++++++++++++++++++++++++++++++++
> fs/fuse/inode.c | 5 +
> 7 files changed, 691 insertions(+), 1 deletion(-)
> create mode 100644 fs/fuse/file_iomap.c
>
>
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index d56d4fd956db99..aa51f25856697d 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -895,6 +895,9 @@ struct fuse_conn {
> /* Is link not implemented by fs? */
> unsigned int no_link:1;
>
> + /* Use fs/iomap for FIEMAP and SEEK_{DATA,HOLE} file operations */
> + unsigned int iomap:1;
> +
> /* Use io_uring for communication */
> unsigned int io_uring;
>
> @@ -1017,6 +1020,11 @@ static inline struct fuse_mount *get_fuse_mount_super(struct super_block *sb)
> return sb->s_fs_info;
> }
>
> +static inline const struct fuse_mount *get_fuse_mount_super_c(const struct super_block *sb)
> +{
> + return sb->s_fs_info;
> +}
> +
Instead of adding this new helper (and the ones below), what about
modifying the existing (non-const) versions of these helpers to take
in const * input args, eg
-static inline struct fuse_mount *get_fuse_mount_super(struct super_block *sb)
+static inline struct fuse_mount *get_fuse_mount_super(const struct
super_block *sb)
{
return sb->s_fs_info;
}
Then, doing something like "const struct fuse_mount *mt =
get_fuse_mount(inode);" would enforce the same guarantees as "const
struct fuse_mount *mt = get_fuse_mount_c(inode);" and we wouldn't need
2 sets of helpers that pretty much do the same thing.
> static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
> {
> return get_fuse_mount_super(sb)->fc;
> @@ -1027,16 +1035,31 @@ static inline struct fuse_mount *get_fuse_mount(struct inode *inode)
> return get_fuse_mount_super(inode->i_sb);
> }
>
> +static inline const struct fuse_mount *get_fuse_mount_c(const struct inode *inode)
> +{
> + return get_fuse_mount_super_c(inode->i_sb);
> +}
> +
> static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
> {
> return get_fuse_mount_super(inode->i_sb)->fc;
> }
>
> +static inline const struct fuse_conn *get_fuse_conn_c(const struct inode *inode)
> +{
> + return get_fuse_mount_super_c(inode->i_sb)->fc;
> +}
> +
> static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
> {
> return container_of(inode, struct fuse_inode, inode);
> }
>
> +static inline const struct fuse_inode *get_fuse_inode_c(const struct inode *inode)
> +{
> + return container_of(inode, struct fuse_inode, inode);
> +}
> +
> static inline u64 get_node_id(struct inode *inode)
> {
> return get_fuse_inode(inode)->nodeid;
> @@ -1577,4 +1600,19 @@ extern void fuse_sysctl_unregister(void);
> #define fuse_sysctl_unregister() do { } while (0)
> #endif /* CONFIG_SYSCTL */
>
> +#if IS_ENABLED(CONFIG_FUSE_IOMAP)
> +# include <linux/fiemap.h>
> +# include <linux/iomap.h>
> +
> +bool fuse_iomap_enabled(void);
> +
> +static inline bool fuse_has_iomap(const struct inode *inode)
> +{
> + return get_fuse_conn_c(inode)->iomap;
> +}
> +#else
> +# define fuse_iomap_enabled(...) (false)
> +# define fuse_has_iomap(...) (false)
> +#endif
> +
> #endif /* _FS_FUSE_I_H */
> diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
> index ca215a3cba3e31..fc7c5bf1cef52d 100644
> --- a/fs/fuse/Kconfig
> +++ b/fs/fuse/Kconfig
> @@ -64,6 +64,29 @@ config FUSE_PASSTHROUGH
>
> If you want to allow passthrough operations, answer Y.
>
> +config FUSE_IOMAP
> + bool "FUSE file IO over iomap"
> + default y
> + depends on FUSE_FS
> + select FS_IOMAP
> + help
> + For supported fuseblk servers, this allows the file IO path to run
> + through the kernel.
I have config FUSE_FS select FS_IOMAP in my patchset (not yet
submitted) that changes fuse buffered writes / writeback handling to
use iomap. Could we just have config FUSE_FS automatically opt into
FS_IOMAP here or do you see a reason that this needs to be a separate
config?
Thanks,
Joanne
> +
> +config FUSE_IOMAP_BY_DEFAULT
> + bool "FUSE file I/O over iomap by default"
> + default n
> + depends on FUSE_IOMAP
> + help
> + Enable sending FUSE file I/O over iomap by default.
> +
> +config FUSE_IOMAP_DEBUG
> + bool "Debug FUSE file IO over iomap"
> + default n
> + depends on FUSE_IOMAP
> + help
> + Enable debugging assertions for the fuse iomap code paths.
> +
> config FUSE_IO_URING
> bool "FUSE communication over io-uring"
> default y
