[PATCH v4 11/21] erofs: add cookie context helper functions

Jeffle Xu
2022-03-07T12:33:58Z

Introduce 'struct erofs_cookie_ctx' for managing cookie for backing
file, and the following introduced API for reading from backing file.

Besides, introduce two helper functions for initializing and cleaning
up erofs_cookie_ctx.

struct erofs_cookie_ctx *
erofs_fscache_get_ctx(struct super_block *sb, char *path);

void erofs_fscache_put_ctx(struct erofs_cookie_ctx *ctx);

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
fs/erofs/fscache.c | 78 +++++++++++++++++++++++++++++++++++++++++++++
fs/erofs/internal.h | 8 +++++
2 files changed, 86 insertions(+)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 9c32f42e1056..77d2b46e7ff1 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -6,6 +6,84 @@

static struct fscache_volume *volume;

+static int erofs_fscache_init_cookie(struct erofs_fscache_context *ctx,
+ char *path)
+{
+ struct fscache_cookie *cookie;
+
+ /*
+ * @object_size shall be non-zero to avoid
+ * FSCACHE_COOKIE_NO_DATA_TO_READ.
+ */
+ cookie = fscache_acquire_cookie(volume, FSCACHE_ADV_WANT_CACHE_SIZE,
+ path, strlen(path),
+ NULL, 0, 0);
+ if (!cookie)
+ return -EINVAL;
+
+ fscache_use_cookie(cookie, false);
+ ctx->cookie = cookie;
+ return 0;
+}
+
+static inline
+void erofs_fscache_cleanup_cookie(struct erofs_fscache_context *ctx)
+{
+ struct fscache_cookie *cookie = ctx->cookie;
+
+ fscache_unuse_cookie(cookie, NULL, NULL);
+ fscache_relinquish_cookie(cookie, false);
+ ctx->cookie = NULL;
+}
+
+static int erofs_fscache_init_ctx(struct erofs_fscache_context *ctx,
+ struct super_block *sb, char *path)
+{
+ int ret;
+
+ ret = erofs_fscache_init_cookie(ctx, path);
+ if (ret) {
+ erofs_err(sb, "failed to init cookie");
+ return ret;
+ }
+
+ return 0;
+}
+
+static inline
+void erofs_fscache_cleanup_ctx(struct erofs_fscache_context *ctx)
+{
+ erofs_fscache_cleanup_cookie(ctx);
+}
+
+struct erofs_fscache_context *erofs_fscache_get_ctx(struct super_block *sb,
+ char *path)
+{
+ struct erofs_fscache_context *ctx;
+ int ret;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ ret = erofs_fscache_init_ctx(ctx, sb, path);
+ if (ret) {
+ kfree(ctx);
+ return ERR_PTR(ret);
+ }
+
+ return ctx;
+}
+
+void erofs_fscache_put_ctx(struct erofs_fscache_context *ctx)
+{
+ if (!ctx)
+ return;
+
+ erofs_fscache_cleanup_ctx(ctx);
+ kfree(ctx);
+}
+
int __init erofs_init_fscache(void)
{
volume = fscache_acquire_volume("erofs", NULL, NULL, 0);
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index c2608a469107..1f5bc69e8e9f 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -97,6 +97,10 @@ struct erofs_sb_lz4_info {
u16 max_pclusterblks;
};

+struct erofs_fscache_context {
+ struct fscache_cookie *cookie;
+};
+
struct erofs_sb_info {
struct erofs_mount_opts opt; /* options */
#ifdef CONFIG_EROFS_FS_ZIP
@@ -621,6 +625,10 @@ 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_context *erofs_fscache_get_ctx(struct super_block *sb,
+ char *path);
+void erofs_fscache_put_ctx(struct erofs_fscache_context *ctx);
+
#define EFSCORRUPTED EUCLEAN /* Filesystem is corrupted */

#endif /* __EROFS_INTERNAL_H */
--
2.27.0