[PATCH v2 10/15] fuse: add support for multiple writeback contexts in fuse

[Kundan Kumar <kundan.kumar@samsung.com>]

Made a helper to fetch writeback context to which an inode is affined.
Use it to perform writeback related operations.

Signed-off-by: Kundan Kumar <kundan.kumar@samsung.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
---
 fs/fuse/file.c              |  8 ++++----
 include/linux/backing-dev.h | 17 +++++++++++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 69874c906319..1194fdd24b01 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1785,7 +1785,6 @@ static void fuse_writepage_finish(struct fuse_writepage_args *wpa)
 	struct fuse_args_pages *ap = &wpa->ia.ap;
 	struct inode *inode = wpa->inode;
 	struct fuse_inode *fi = get_fuse_inode(inode);
-	struct backing_dev_info *bdi = inode_to_bdi(inode);
 	int i;
 
 	for (i = 0; i < ap->num_folios; i++) {
@@ -1795,8 +1794,9 @@ static void fuse_writepage_finish(struct fuse_writepage_args *wpa)
 		 * contention and noticeably improves performance.
 		 */
 		folio_end_writeback(ap->folios[i]);
-		dec_wb_stat(&bdi->wb_ctx[0]->wb, WB_WRITEBACK);
-		wb_writeout_inc(&bdi->wb_ctx[0]->wb);
+
+		bdi_wb_stat_mod(inode, -1);
+		bdi_wb_writeout_inc(inode);
 	}
 
 	wake_up(&fi->page_waitq);
@@ -1990,7 +1990,7 @@ static void fuse_writepage_args_page_fill(struct fuse_writepage_args *wpa, struc
 	ap->descs[folio_index].offset = 0;
 	ap->descs[folio_index].length = folio_size(folio);
 
-	inc_wb_stat(&inode_to_bdi(inode)->wb_ctx[0]->wb, WB_WRITEBACK);
+	bdi_wb_stat_mod(inode, 1);
 }
 
 static struct fuse_writepage_args *fuse_writepage_args_setup(struct folio *folio,
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 831cd9f51162..5ed8294e0c0e 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -46,6 +46,9 @@ extern struct list_head bdi_list;
 
 extern struct workqueue_struct *bdi_wq;
 
+static inline struct bdi_writeback_ctx *
+fetch_bdi_writeback_ctx(struct inode *inode);
+
 static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
 {
 	return test_bit(WB_has_dirty_io, &wb->state);
@@ -104,6 +107,20 @@ static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
 
 extern void wb_writeout_inc(struct bdi_writeback *wb);
 
+static inline void bdi_wb_stat_mod(struct inode *inode, s64 amount)
+{
+	struct bdi_writeback_ctx *bdi_wb_ctx = fetch_bdi_writeback_ctx(inode);
+
+	wb_stat_mod(&bdi_wb_ctx->wb, WB_WRITEBACK, amount);
+}
+
+static inline void bdi_wb_writeout_inc(struct inode *inode)
+{
+	struct bdi_writeback_ctx *bdi_wb_ctx = fetch_bdi_writeback_ctx(inode);
+
+	wb_writeout_inc(&bdi_wb_ctx->wb);
+}
+
 /*
  * maximal error of a stat counter.
  */
-- 
2.25.1