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Subject[PATCH v9 17/21] erofs: implement fscache-based metadata read
Date
Implement the data plane of reading metadata from primary data blob
over fscache.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
fs/erofs/data.c | 19 +++++++++++++++----
fs/erofs/fscache.c | 27 +++++++++++++++++++++++++++
2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 14b64d960541..bb9c1fd48c19 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -6,6 +6,7 @@
*/
#include "internal.h"
#include <linux/prefetch.h>
+#include <linux/sched/mm.h>
#include <linux/dax.h>
#include <trace/events/erofs.h>

@@ -35,14 +36,20 @@ void *erofs_bread(struct erofs_buf *buf, struct inode *inode,
erofs_off_t offset = blknr_to_addr(blkaddr);
pgoff_t index = offset >> PAGE_SHIFT;
struct page *page = buf->page;
+ struct folio *folio;
+ unsigned int nofs_flag;

if (!page || page->index != index) {
erofs_put_metabuf(buf);
- page = read_cache_page_gfp(mapping, index,
- mapping_gfp_constraint(mapping, ~__GFP_FS));
- if (IS_ERR(page))
- return page;
+
+ nofs_flag = memalloc_nofs_save();
+ folio = read_cache_folio(mapping, index, NULL, NULL);
+ memalloc_nofs_restore(nofs_flag);
+ if (IS_ERR(folio))
+ return folio;
+
/* should already be PageUptodate, no need to lock page */
+ page = folio_file_page(folio, index);
buf->page = page;
}
if (buf->kmap_type == EROFS_NO_KMAP) {
@@ -63,6 +70,10 @@ void *erofs_bread(struct erofs_buf *buf, struct inode *inode,
void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
erofs_blk_t blkaddr, enum erofs_kmap_type type)
{
+ if (erofs_is_fscache_mode(sb))
+ return erofs_bread(buf, EROFS_SB(sb)->s_fscache->inode,
+ blkaddr, type);
+
return erofs_bread(buf, sb->s_bdev->bd_inode, blkaddr, type);
}

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 066f68c062e2..3f00eb34ac35 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -58,7 +58,34 @@ static int erofs_fscache_read_folios(struct fscache_cookie *cookie,
return ret;
}

+static int erofs_fscache_meta_readpage(struct file *data, struct page *page)
+{
+ int ret;
+ struct folio *folio = page_folio(page);
+ struct super_block *sb = folio_mapping(folio)->host->i_sb;
+ struct erofs_map_dev mdev = {
+ .m_deviceid = 0,
+ .m_pa = folio_pos(folio),
+ };
+
+ ret = erofs_map_dev(sb, &mdev);
+ if (ret)
+ goto out;
+
+ ret = erofs_fscache_read_folios(mdev.m_fscache->cookie,
+ folio_mapping(folio), folio_pos(folio),
+ folio_size(folio), mdev.m_pa);
+ if (ret)
+ goto out;
+
+ folio_mark_uptodate(folio);
+out:
+ folio_unlock(folio);
+ return ret;
+}
+
static const struct address_space_operations erofs_fscache_meta_aops = {
+ .readpage = erofs_fscache_meta_readpage,
};

/*
--
2.27.0
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