[Virtio-fs] [PATCH v6 2/7] fuse: make DAX mount option a tri-state
Vivek Goyal
vgoyal at redhat.com
Mon Oct 18 14:10:27 UTC 2021
On Mon, Oct 11, 2021 at 11:00:47AM +0800, Jeffle Xu wrote:
> We add 'always', 'never', and 'inode' (default). '-o dax' continues to
> operate the same which is equivalent to 'always'. To be consistemt with
> ext4/xfs's tri-state mount option, when neither '-o dax' nor '-o dax='
> option is specified, the default behaviour is equal to 'inode'.
Hi Jeffle,
I am not sure when -o "dax=inode" is used as a default? If user
specifies, "-o dax" then it is equal to "-o dax=always", otherwise
user will explicitly specify "-o dax=always/never/inode". So when
is dax=inode is used as default?
>
> By the time this patch is applied, 'inode' mode is actually equal to
> 'always' mode, before the per-file DAX flag is introduced in the
> following patch.
>
> Signed-off-by: Jeffle Xu <jefflexu at linux.alibaba.com>
> ---
> fs/fuse/dax.c | 19 ++++++++++++++++---
> fs/fuse/fuse_i.h | 14 ++++++++++++--
> fs/fuse/inode.c | 10 +++++++---
> fs/fuse/virtio_fs.c | 16 ++++++++++++++--
> 4 files changed, 49 insertions(+), 10 deletions(-)
>
> diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
> index 1eb6538bf1b2..4c6c64efc950 100644
> --- a/fs/fuse/dax.c
> +++ b/fs/fuse/dax.c
> @@ -1284,11 +1284,14 @@ static int fuse_dax_mem_range_init(struct fuse_conn_dax *fcd)
> return ret;
> }
>
> -int fuse_dax_conn_alloc(struct fuse_conn *fc, struct dax_device *dax_dev)
> +int fuse_dax_conn_alloc(struct fuse_conn *fc, enum fuse_dax_mode dax_mode,
> + struct dax_device *dax_dev)
> {
> struct fuse_conn_dax *fcd;
> int err;
>
> + fc->dax_mode = dax_mode;
> +
> if (!dax_dev)
> return 0;
>
> @@ -1335,11 +1338,21 @@ static const struct address_space_operations fuse_dax_file_aops = {
> static bool fuse_should_enable_dax(struct inode *inode)
> {
> struct fuse_conn *fc = get_fuse_conn(inode);
> + unsigned int dax_mode = fc->dax_mode;
> +
> + if (dax_mode == FUSE_DAX_NEVER)
> + return false;
>
> - if (fc->dax)
> + /*
> + * If 'dax=always/inode', fc->dax couldn't be NULL even when fuse
> + * daemon doesn't support DAX, since the mount routine will fail
> + * early in this case.
> + */
> + if (dax_mode == FUSE_DAX_ALWAYS)
> return true;
>
> - return false;
> + /* dax_mode == FUSE_DAX_INODE */
> + return true;
So as of this patch except FUSE_DAX_NEVER return true and this will
change in later patches for FUSE_DAX_INODE? If that's the case, keep
it simple in this patch and change it later in the patch series.
fuse_should_enable_dax()
{
if (dax_mode == FUSE_DAX_NEVER)
return false;
return true;
}
> }
>
> void fuse_dax_inode_init(struct inode *inode)
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index 319596df5dc6..5abf9749923f 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -480,6 +480,12 @@ struct fuse_dev {
> struct list_head entry;
> };
>
> +enum fuse_dax_mode {
> + FUSE_DAX_INODE,
> + FUSE_DAX_ALWAYS,
> + FUSE_DAX_NEVER,
> +};
> +
> struct fuse_fs_context {
> int fd;
> struct file *file;
> @@ -497,7 +503,7 @@ struct fuse_fs_context {
> bool no_control:1;
> bool no_force_umount:1;
> bool legacy_opts_show:1;
> - bool dax:1;
> + enum fuse_dax_mode dax_mode;
> unsigned int max_read;
> unsigned int blksize;
> const char *subtype;
> @@ -802,6 +808,9 @@ struct fuse_conn {
> struct list_head devices;
>
> #ifdef CONFIG_FUSE_DAX
> + /* dax mode: FUSE_DAX_* (always, never or per-file) */
> + enum fuse_dax_mode dax_mode;
> +
> /* Dax specific conn data, non-NULL if DAX is enabled */
> struct fuse_conn_dax *dax;
> #endif
> @@ -1255,7 +1264,8 @@ ssize_t fuse_dax_read_iter(struct kiocb *iocb, struct iov_iter *to);
> ssize_t fuse_dax_write_iter(struct kiocb *iocb, struct iov_iter *from);
> int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma);
> int fuse_dax_break_layouts(struct inode *inode, u64 dmap_start, u64 dmap_end);
> -int fuse_dax_conn_alloc(struct fuse_conn *fc, struct dax_device *dax_dev);
> +int fuse_dax_conn_alloc(struct fuse_conn *fc, enum fuse_dax_mode mode,
> + struct dax_device *dax_dev);
> void fuse_dax_conn_free(struct fuse_conn *fc);
> bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi);
> void fuse_dax_inode_init(struct inode *inode);
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index 36cd03114b6d..b4b41683e97e 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -742,8 +742,12 @@ static int fuse_show_options(struct seq_file *m, struct dentry *root)
> seq_printf(m, ",blksize=%lu", sb->s_blocksize);
> }
> #ifdef CONFIG_FUSE_DAX
> - if (fc->dax)
> - seq_puts(m, ",dax");
> + if (fc->dax_mode == FUSE_DAX_ALWAYS)
> + seq_puts(m, ",dax=always");
So if somebody mounts with "-o dax" then kernel previous to this change
will show "dax" and kernel after this change will show "dax=always"?
How about not change the behavior. Keep a mode say FUSE_DAX_LEGACY which
will be set when user specifies "-o dax". Internally FUSE_DAX_LEGACY
and FUSE_DAX_ALWAYS will be same.
if (fc->dax_mode == FUSE_DAX_LEGACY)
seq_puts(m, ",dax");
Thanks
Vivek
> + else if (fc->dax_mode == FUSE_DAX_NEVER)
> + seq_puts(m, ",dax=never");
> + else if (fc->dax_mode == FUSE_DAX_INODE)
> + seq_puts(m, ",dax=inode");
> #endif
>
> return 0;
> @@ -1493,7 +1497,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
> sb->s_subtype = ctx->subtype;
> ctx->subtype = NULL;
> if (IS_ENABLED(CONFIG_FUSE_DAX)) {
> - err = fuse_dax_conn_alloc(fc, ctx->dax_dev);
> + err = fuse_dax_conn_alloc(fc, ctx->dax_mode, ctx->dax_dev);
> if (err)
> goto err;
> }
> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
> index 0ad89c6629d7..58cfbaeb4a7d 100644
> --- a/fs/fuse/virtio_fs.c
> +++ b/fs/fuse/virtio_fs.c
> @@ -88,12 +88,21 @@ struct virtio_fs_req_work {
> static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
> struct fuse_req *req, bool in_flight);
>
> +static const struct constant_table dax_param_enums[] = {
> + {"inode", FUSE_DAX_INODE },
> + {"always", FUSE_DAX_ALWAYS },
> + {"never", FUSE_DAX_NEVER },
> + {}
> +};
> +
> enum {
> OPT_DAX,
> + OPT_DAX_ENUM,
> };
>
> static const struct fs_parameter_spec virtio_fs_parameters[] = {
> fsparam_flag("dax", OPT_DAX),
> + fsparam_enum("dax", OPT_DAX_ENUM, dax_param_enums),
> {}
> };
>
> @@ -110,7 +119,10 @@ static int virtio_fs_parse_param(struct fs_context *fsc,
>
> switch (opt) {
> case OPT_DAX:
> - ctx->dax = 1;
> + ctx->dax_mode = FUSE_DAX_ALWAYS;
> + break;
> + case OPT_DAX_ENUM:
> + ctx->dax_mode = result.uint_32;
> break;
> default:
> return -EINVAL;
> @@ -1326,7 +1338,7 @@ static int virtio_fs_fill_super(struct super_block *sb, struct fs_context *fsc)
>
> /* virtiofs allocates and installs its own fuse devices */
> ctx->fudptr = NULL;
> - if (ctx->dax) {
> + if (ctx->dax_mode != FUSE_DAX_NEVER) {
> if (!fs->dax_dev) {
> err = -EINVAL;
> pr_err("virtio-fs: dax can't be enabled as filesystem"
> --
> 2.27.0
>
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