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Subject[RFC 15/19] erofs: implement fscache-based metadata read
Date
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
fs/erofs/data.c | 5 +++--
fs/erofs/fscache.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
fs/erofs/internal.h | 3 +++
fs/erofs/super.c | 10 ++++++----
4 files changed, 57 insertions(+), 6 deletions(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index cf71082bd52f..47bd3d0ae94c 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -12,6 +12,7 @@
struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr)
{
struct address_space * mapping;
+ struct erofs_sb_info *sbi;
struct page *page;

if (sb->s_bdev) {
@@ -19,8 +20,8 @@ struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr)
page = read_cache_page_gfp(mapping, blkaddr,
mapping_gfp_constraint(mapping, ~__GFP_FS));
} else {
- /* TODO: fscache based data path */
- page = ERR_PTR(-EINVAL);
+ sbi = EROFS_SB(sb);
+ page = erofs_readpage_from_fscache(sbi->bootstrap, blkaddr);
}

/* should already be PageUptodate */
diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index cf550fdedd1e..6fe31d410cbd 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -1,5 +1,50 @@
#include "internal.h"

+static int erofs_begin_cache_operation(struct netfs_read_request *rreq)
+{
+ return fscache_begin_read_operation(&rreq->cache_resources,
+ rreq->netfs_priv);
+}
+
+static void erofs_priv_cleanup(struct address_space *mapping, void *netfs_priv)
+{
+}
+
+const struct netfs_read_request_ops erofs_req_ops = {
+ .begin_cache_operation = erofs_begin_cache_operation,
+ .cleanup = erofs_priv_cleanup,
+};
+
+struct page *erofs_readpage_from_fscache(struct fscache_cookie *cookie,
+ pgoff_t index)
+{
+ int ret = -ENOMEM;
+ struct folio *folio;
+ struct page *page;
+
+ page = alloc_page(GFP_KERNEL);
+ if (unlikely(!page)) {
+ printk("failed to allocate page\n");
+ goto err;
+ }
+
+ page->index = index;
+ folio = page_folio(page);
+
+ ret = netfs_readpage_demand(folio, &erofs_req_ops, cookie);
+ if (unlikely(ret || !PageUptodate(page))) {
+ printk("failed to read from fscache\n");
+ goto err_page;
+ }
+
+ return page;
+
+err_page:
+ __free_page(page);
+err:
+ return ERR_PTR(ret);
+}
+
int erofs_fscache_init(struct erofs_sb_info *sbi, char *bootstrap_path)
{
sbi->volume = fscache_acquire_volume("erofs", NULL, 0);
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 8136ec63a9de..d60d9ffaef2a 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -577,6 +577,9 @@ static inline int z_erofs_load_lzma_config(struct super_block *sb,
int erofs_fscache_init(struct erofs_sb_info *sbi, char *bootstrap_path);
void erofs_fscache_cleanup(struct erofs_sb_info *sbi);

+struct page *erofs_readpage_from_fscache(struct fscache_cookie *cookie,
+ pgoff_t index);
+
#define EFSCORRUPTED EUCLEAN /* Filesystem is corrupted */

#endif /* __EROFS_INTERNAL_H */
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index f2a5f4cd53fd..bb68bc81a1a7 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -330,21 +330,23 @@ static int erofs_init_devices(struct super_block *sb,

static int erofs_read_superblock(struct super_block *sb)
{
- struct erofs_sb_info *sbi;
+ struct erofs_sb_info *sbi = EROFS_SB(sb);
struct page *page;
struct erofs_super_block *dsb;
unsigned int blkszbits;
void *data;
int ret;

- page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
+ if (sb->s_bdev)
+ page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
+ else
+ page = erofs_readpage_from_fscache(sbi->bootstrap, 0);
+
if (IS_ERR(page)) {
erofs_err(sb, "cannot read erofs superblock");
return PTR_ERR(page);
}

- sbi = EROFS_SB(sb);
-
data = kmap(page);
dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);

--
2.27.0
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