On Wed, Apr 06, 2022 at 03:56:04PM +0800, Jeffle Xu wrote:
> Introduce one anonymous inode managing page cache for data blob. Then
> erofs could read directly from the address space of the anonymous inode
> when cache hit.
Introduce one anonymous inode for data blobs so that erofs
can cache metadata directly within such anonymous inode.
>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
Yeah, I think currently we can live with that:
Reviewed-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
Thanks,
Gao Xiang
> ---
> fs/erofs/fscache.c | 39 ++++++++++++++++++++++++++++++++++++---
> fs/erofs/internal.h | 6 ++++--
> 2 files changed, 40 insertions(+), 5 deletions(-)
>
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 67a3c4935245..1c88614203d2 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -5,17 +5,22 @@
> #include <linux/fscache.h>
> #include "internal.h"
>
> +static const struct address_space_operations erofs_fscache_meta_aops = {
> +};
> +
> /*
> * Create an fscache context for data blob.
> * Return: 0 on success and allocated fscache context is assigned to @fscache,
> * negative error number on failure.
> */
> int erofs_fscache_register_cookie(struct super_block *sb,
> - struct erofs_fscache **fscache, char *name)
> + struct erofs_fscache **fscache,
> + char *name, bool need_inode)
> {
> struct fscache_volume *volume = EROFS_SB(sb)->volume;
> struct erofs_fscache *ctx;
> struct fscache_cookie *cookie;
> + int ret;
>
> ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> if (!ctx)
> @@ -25,15 +30,40 @@ int erofs_fscache_register_cookie(struct super_block *sb,
> name, strlen(name), NULL, 0, 0);
> if (!cookie) {
> erofs_err(sb, "failed to get cookie for %s", name);
> - kfree(name);
> - return -EINVAL;
> + ret = -EINVAL;
> + goto err;
> }
>
> fscache_use_cookie(cookie, false);
> ctx->cookie = cookie;
>
> + if (need_inode) {
> + struct inode *const inode = new_inode(sb);
> +
> + if (!inode) {
> + erofs_err(sb, "failed to get anon inode for %s", name);
> + ret = -ENOMEM;
> + goto err_cookie;
> + }
> +
> + set_nlink(inode, 1);
> + inode->i_size = OFFSET_MAX;
> + inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
> + mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
> +
> + ctx->inode = inode;
> + }
> +
> *fscache = ctx;
> return 0;
> +
> +err_cookie:
> + fscache_unuse_cookie(ctx->cookie, NULL, NULL);
> + fscache_relinquish_cookie(ctx->cookie, false);
> + ctx->cookie = NULL;
> +err:
> + kfree(ctx);
> + return ret;
> }
>
> void erofs_fscache_unregister_cookie(struct erofs_fscache **fscache)
> @@ -47,6 +77,9 @@ void erofs_fscache_unregister_cookie(struct erofs_fscache **fscache)
> fscache_relinquish_cookie(ctx->cookie, false);
> ctx->cookie = NULL;
>
> + iput(ctx->inode);
> + ctx->inode = NULL;
> +
> kfree(ctx);
> *fscache = NULL;
> }
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index c6a3351a4d7d..3a4a344cfed3 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -99,6 +99,7 @@ struct erofs_sb_lz4_info {
>
> struct erofs_fscache {
> struct fscache_cookie *cookie;
> + struct inode *inode;
> };
>
> struct erofs_sb_info {
> @@ -632,7 +633,8 @@ int erofs_fscache_register_fs(struct super_block *sb);
> void erofs_fscache_unregister_fs(struct super_block *sb);
>
> int erofs_fscache_register_cookie(struct super_block *sb,
> - struct erofs_fscache **fscache, char *name);
> + struct erofs_fscache **fscache,
> + char *name, bool need_inode);
> void erofs_fscache_unregister_cookie(struct erofs_fscache **fscache);
> #else
> static inline int erofs_fscache_register_fs(struct super_block *sb) { return 0; }
> @@ -640,7 +642,7 @@ static inline void erofs_fscache_unregister_fs(struct super_block *sb) {}
>
> static inline int erofs_fscache_register_cookie(struct super_block *sb,
> struct erofs_fscache **fscache,
> - char *name)
> + char *name, bool need_inode)
> {
> return -EOPNOTSUPP;
> }
> --
> 2.27.0
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