[PATCH v4 12/21] erofs: add anonymous inode managing page cache of blob file

Jeffle Xu
2022-03-07T12:34:16Z

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 | 45 ++++++++++++++++++++++++++++++++++++++++++---
fs/erofs/internal.h | 3 ++-
2 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 77d2b46e7ff1..4d83125ff896 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -6,6 +6,9 @@

static struct fscache_volume *volume;

+static const struct address_space_operations erofs_fscache_blob_aops = {
+};
+
static int erofs_fscache_init_cookie(struct erofs_fscache_context *ctx,
char *path)
{
@@ -36,8 +39,34 @@ void erofs_fscache_cleanup_cookie(struct erofs_fscache_context *ctx)
ctx->cookie = NULL;
}

+static int erofs_fscache_get_inode(struct erofs_fscache_context *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 | __GFP_HIGHMEM | __GFP_MOVABLE);
+ ctx->inode = inode;
+ return 0;
+}
+
+static inline
+void erofs_fscache_put_inode(struct erofs_fscache_context *ctx)
+{
+ iput(ctx->inode);
+ ctx->inode = NULL;
+}
+
static int erofs_fscache_init_ctx(struct erofs_fscache_context *ctx,
- struct super_block *sb, char *path)
+ struct super_block *sb, char *path,
+ bool need_inode)
{
int ret;

@@ -47,6 +76,15 @@ static int erofs_fscache_init_ctx(struct erofs_fscache_context *ctx,
return ret;
}

+ if (need_inode) {
+ ret = erofs_fscache_get_inode(ctx, sb);
+ if (ret) {
+ erofs_err(sb, "failed to get anonymous inode");
+ erofs_fscache_cleanup_cookie(ctx);
+ return ret;
+ }
+ }
+
return 0;
}

@@ -54,10 +92,11 @@ static inline
void erofs_fscache_cleanup_ctx(struct erofs_fscache_context *ctx)
{
erofs_fscache_cleanup_cookie(ctx);
+ erofs_fscache_put_inode(ctx);
}

struct erofs_fscache_context *erofs_fscache_get_ctx(struct super_block *sb,
- char *path)
+ char *path, bool need_inode)
{
struct erofs_fscache_context *ctx;
int ret;
@@ -66,7 +105,7 @@ struct erofs_fscache_context *erofs_fscache_get_ctx(struct super_block *sb,
if (!ctx)
return ERR_PTR(-ENOMEM);

- ret = erofs_fscache_init_ctx(ctx, sb, path);
+ ret = erofs_fscache_init_ctx(ctx, sb, path, need_inode);
if (ret) {
kfree(ctx);
return ERR_PTR(ret);
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 1f5bc69e8e9f..bb5e992fe0df 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -99,6 +99,7 @@ struct erofs_sb_lz4_info {

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

struct erofs_sb_info {
@@ -626,7 +627,7 @@ int erofs_init_fscache(void);
void erofs_exit_fscache(void);

struct erofs_fscache_context *erofs_fscache_get_ctx(struct super_block *sb,
- char *path);
+ char *path, bool need_inode);
void erofs_fscache_put_ctx(struct erofs_fscache_context *ctx);

#define EFSCORRUPTED EUCLEAN /* Filesystem is corrupted */
--
2.27.0