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

Jeffle Xu
2022-03-25T12:23:26Z

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)
+{
+ 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)
+{
+ 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");
+ goto err_cookie;
+ }
+ }
+
return ctx;
+
+err_cookie:
+ erofs_fscache_cleanup_cookie(ctx);
err:
kfree(ctx);
return ERR_PTR(ret);
@@ -65,6 +103,7 @@ void erofs_fscache_put(struct erofs_fscache *ctx)
return;

erofs_fscache_cleanup_cookie(ctx);
+ erofs_fscache_put_inode(ctx);
kfree(ctx);
}

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index d4f2b43cedae..459f31803c3b 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -98,6 +98,7 @@ struct erofs_sb_lz4_info {

struct erofs_fscache {
struct fscache_cookie *cookie;
+ struct inode *inode;
};

struct erofs_sb_info {
@@ -625,14 +626,16 @@ static inline int z_erofs_load_lzma_config(struct super_block *sb,
int erofs_init_fscache(void);
void erofs_exit_fscache(void);

-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);
void erofs_fscache_put(struct erofs_fscache *ctx);
#else
static inline int erofs_init_fscache(void) { return 0; }
static inline void erofs_exit_fscache(void) {}

static inline struct erofs_fscache *erofs_fscache_get(struct super_block *sb,
- char *path)
+ char *path,
+ bool need_inode)
{
return ERR_PTR(-EOPNOTSUPP);
}
--
2.27.0