[RFC PATCH 7/9] f2fs:Make GC aware of large folios

[Nanzhe Zhao <nzzhao@xxxxxxx>]

Previously, the GC (Garbage Collection) logic for performing I/O and
marking folios dirty only supported order-0 folios and lacked awareness
of higher-order folios. To enable GC to correctly handle higher-order
folios, we made two changes:

- In `move_data_page`, we now use `f2fs_iomap_set_range_dirty` to mark
  only the sub-part of the folio corresponding to `bidx` as dirty,
  instead of the entire folio.

- The `f2fs_submit_page_read` function has been augmented with an
  `index` parameter, allowing it to precisely identify which sub-page
  of the current folio is being submitted.

Signed-off-by: Nanzhe Zhao <nzzhao@xxxxxxx>
---
 fs/f2fs/data.c | 13 +++++++------
 fs/f2fs/gc.c   | 37 +++++++++++++++++++++++--------------
 2 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index b7bef2a28c8e..5ecd08a3dd0b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1096,7 +1096,7 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
 /* This can handle encryption stuffs */
 static int f2fs_submit_page_read(struct inode *inode, struct folio *folio,
 				 block_t blkaddr, blk_opf_t op_flags,
-				 bool for_write)
+				 pgoff_t index, bool for_write)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	struct bio *bio;
@@ -1109,7 +1109,8 @@ static int f2fs_submit_page_read(struct inode *inode, struct folio *folio,
 	/* wait for GCed page writeback via META_MAPPING */
 	f2fs_wait_on_block_writeback(inode, blkaddr);
 
-	if (!bio_add_folio(bio, folio, PAGE_SIZE, 0)) {
+	if (!bio_add_folio(bio, folio, PAGE_SIZE,
+			   (index - folio->index) << PAGE_SHIFT)) {
 		iostat_update_and_unbind_ctx(bio);
 		if (bio->bi_private)
 			mempool_free(bio->bi_private, bio_post_read_ctx_pool);
@@ -1276,8 +1277,8 @@ struct folio *f2fs_get_read_data_folio(struct inode *inode, pgoff_t index,
 		return folio;
 	}
 
-	err = f2fs_submit_page_read(inode, folio, dn.data_blkaddr,
-						op_flags, for_write);
+	err = f2fs_submit_page_read(inode, folio, dn.data_blkaddr, op_flags,
+				    index, for_write);
 	if (err)
 		goto put_err;
 	return folio;
@@ -3651,8 +3652,8 @@ static int f2fs_write_begin(const struct kiocb *iocb,
 			goto put_folio;
 		}
 		err = f2fs_submit_page_read(use_cow ?
-				F2FS_I(inode)->cow_inode : inode,
-				folio, blkaddr, 0, true);
+			F2FS_I(inode)->cow_inode : inode, folio,
+			blkaddr, 0, folio->index, true);
 		if (err)
 			goto put_folio;
 
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 098e9f71421e..6d28f01bec42 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1475,22 +1475,31 @@ static int move_data_page(struct inode *inode, block_t bidx, int gc_type,
 			err = -EAGAIN;
 			goto out;
 		}
-		folio_mark_dirty(folio);
 		folio_set_f2fs_gcing(folio);
+#ifdef CONFIG_F2FS_IOMAP_FOLIO_STATE
+		if (!folio_test_large(folio)) {
+			folio_mark_dirty(folio);
+		} else {
+			f2fs_iomap_set_range_dirty(folio, (bidx - folio->index) << PAGE_SHIFT,
+				PAGE_SIZE);
+		}
+#else
+		folio_mark_dirty(folio);
+#endif
 	} else {
-		struct f2fs_io_info fio = {
-			.sbi = F2FS_I_SB(inode),
-			.ino = inode->i_ino,
-			.type = DATA,
-			.temp = COLD,
-			.op = REQ_OP_WRITE,
-			.op_flags = REQ_SYNC,
-			.old_blkaddr = NULL_ADDR,
-			.folio = folio,
-			.encrypted_page = NULL,
-			.need_lock = LOCK_REQ,
-			.io_type = FS_GC_DATA_IO,
-		};
+		struct f2fs_io_info fio = { .sbi = F2FS_I_SB(inode),
+					    .ino = inode->i_ino,
+					    .type = DATA,
+					    .temp = COLD,
+					    .op = REQ_OP_WRITE,
+					    .op_flags = REQ_SYNC,
+					    .old_blkaddr = NULL_ADDR,
+					    .folio = folio,
+					    .encrypted_page = NULL,
+					    .need_lock = LOCK_REQ,
+					    .io_type = FS_GC_DATA_IO,
+					    .idx = bidx - folio->index,
+					    .cnt = 1 };
 		bool is_dirty = folio_test_dirty(folio);
 
 retry:
-- 
2.34.1