Re: [Linux-cachefs] [PATCH v6 13/22] erofs: add anonymous inode managing page cache of blob file

Gao Xiang
2022-03-25T13:46:49Z

On Fri, Mar 25, 2022 at 08:22:14PM +0800, Jeffle Xu wrote:
> Introduce one anonymous inode for managing page cache of corresponding
> blob file. Then erofs could read directly from the address space of the
> anonymous inode when cache hit.
>
> Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
> ---
> fs/erofs/fscache.c | 41 ++++++++++++++++++++++++++++++++++++++++-
> fs/erofs/internal.h | 7 +++++--
> 2 files changed, 45 insertions(+), 3 deletions(-)
>
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 73235fd43bf6..30383d9adb62 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -7,6 +7,9 @@
>
> static struct fscache_volume *volume;
>
> +static const struct address_space_operations erofs_fscache_blob_aops = {
> +};
> +
> static int erofs_fscache_init_cookie(struct erofs_fscache *ctx, char *path)
> {
> struct fscache_cookie *cookie;
> @@ -31,6 +34,29 @@ static inline void erofs_fscache_cleanup_cookie(struct erofs_fscache *ctx)
> ctx->cookie = NULL;
> }
>
> +static int erofs_fscache_get_inode(struct erofs_fscache *ctx,
> + struct super_block *sb)

I think it can be folded as well.

> +{
> + struct inode *const inode = new_inode(sb);
> +
> + if (!inode)
> + return -ENOMEM;
> +
> + set_nlink(inode, 1);
> + inode->i_size = OFFSET_MAX;
> + inode->i_mapping->a_ops = &erofs_fscache_blob_aops;
> + mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
> +
> + ctx->inode = inode;
> + return 0;
> +}
> +
> +static inline void erofs_fscache_put_inode(struct erofs_fscache *ctx)

Ditto.

> +{
> + iput(ctx->inode);
> + ctx->inode = NULL;
> +}
> +
> /*
> * erofs_fscache_get - create an fscache context for blob file
> * @sb: superblock
> @@ -38,7 +64,8 @@ static inline void erofs_fscache_cleanup_cookie(struct erofs_fscache *ctx)
> *
> * Return: fscache context on success, ERR_PTR() on failure.
> */
> -struct erofs_fscache *erofs_fscache_get(struct super_block *sb, char *path)
> +struct erofs_fscache *erofs_fscache_get(struct super_block *sb, char *path,
> + bool need_inode)
> {
> struct erofs_fscache *ctx;
> int ret;
> @@ -53,7 +80,18 @@ struct erofs_fscache *erofs_fscache_get(struct super_block *sb, char *path)
> goto err;
> }
>
> + if (need_inode) {
> + ret = erofs_fscache_get_inode(ctx, sb);
> + if (ret) {
> + erofs_err(sb, "failed to get anonymous inode");

failed to get fscache inode of [path].

Thanks,
Gao Xiang