[PATCH 13/20] f2fs: support subpage blocks in swapfile activation

[Daeho Jeong <daeho43@gmail.com>]

From: Daeho Jeong <daehojeong@google.com>

The swap subsystem works in PAGE_SIZE units. Ignore a partial tail
page, require PAGE_SIZE aligned extents, and convert block counts and
addresses to pages for swap. When migrating blocks, mark only the
migrated block, not its whole page, dirty in the folio state.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
 fs/f2fs/data.c | 43 ++++++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 77915a2eb190..929a2beef379 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -5876,8 +5876,8 @@ static int f2fs_migrate_blocks(struct inode *inode, block_t start_blk,
 			}
 
 			f2fs_ffs_mark_subrange_dirty(folio,
-				offset_in_folio(folio, (loff_t)blkidx << PAGE_SHIFT),
-				PAGE_SIZE);
+				f2fs_folio_byte_offset(sbi, folio, blkidx),
+				F2FS_BLKSIZE(sbi));
 			folio_mark_dirty(folio);
 			f2fs_folio_put(folio, true);
 		}
@@ -5909,8 +5909,10 @@ static int check_swap_activate(struct swap_info_struct *sis,
 	struct address_space *mapping = swap_file->f_mapping;
 	struct inode *inode = mapping->host;
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	unsigned int blks_per_page = F2FS_BLKS_PER_PAGE(sbi);
 	block_t cur_lblock;
 	block_t last_lblock;
+	block_t max_lblock;
 	block_t pblock;
 	block_t lowest_pblock = -1;
 	block_t highest_pblock = 0;
@@ -5925,9 +5927,12 @@ static int check_swap_activate(struct swap_info_struct *sis,
 	 * to be very smart.
 	 */
 	cur_lblock = 0;
-	last_lblock = F2FS_BYTES_TO_BLK(sbi, i_size_read(inode));
+	/* swap uses whole pages only; ignore a partial tail page */
+	last_lblock = round_down(F2FS_BYTES_TO_BLK(sbi, i_size_read(inode)),
+				 blks_per_page);
+	max_lblock = min_t(u64, last_lblock, (u64)sis->max * blks_per_page);
 
-	while (cur_lblock < last_lblock && cur_lblock < sis->max) {
+	while (cur_lblock < max_lblock) {
 		struct f2fs_map_blocks map;
 		bool last_extent = false;
 retry:
@@ -5962,7 +5967,7 @@ static int check_swap_activate(struct swap_info_struct *sis,
 			not_aligned++;
 
 			nr_pblocks = roundup(nr_pblocks, blks_per_sec);
-			if (cur_lblock + nr_pblocks > sis->max)
+			if (cur_lblock + nr_pblocks > max_lblock)
 				nr_pblocks -= blks_per_sec;
 
 			/* this extent is last one */
@@ -5983,20 +5988,28 @@ static int check_swap_activate(struct swap_info_struct *sis,
 			goto retry;
 		}
 
-		if (cur_lblock + nr_pblocks >= sis->max)
-			nr_pblocks = sis->max - cur_lblock;
+		if (cur_lblock + nr_pblocks >= max_lblock)
+			nr_pblocks = max_lblock - cur_lblock;
+
+		if (pblock % blks_per_page || nr_pblocks % blks_per_page) {
+			f2fs_err(sbi, "Swapfile extent is not aligned to PAGE_SIZE");
+			ret = -EINVAL;
+			goto out;
+		}
 
 		if (cur_lblock) {	/* exclude the header page */
-			if (pblock < lowest_pblock)
-				lowest_pblock = pblock;
-			if (pblock + nr_pblocks - 1 > highest_pblock)
-				highest_pblock = pblock + nr_pblocks - 1;
+			if (pblock / blks_per_page < lowest_pblock)
+				lowest_pblock = pblock / blks_per_page;
+			if ((pblock + nr_pblocks) / blks_per_page - 1 > highest_pblock)
+				highest_pblock = (pblock + nr_pblocks) / blks_per_page - 1;
 		}
 
 		/*
 		 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
 		 */
-		ret = add_swap_extent(sis, cur_lblock, nr_pblocks, pblock);
+		ret = add_swap_extent(sis, cur_lblock / blks_per_page,
+				      nr_pblocks / blks_per_page,
+				      pblock / blks_per_page);
 		if (ret < 0)
 			goto out;
 		nr_extents += ret;
@@ -6005,9 +6018,9 @@ static int check_swap_activate(struct swap_info_struct *sis,
 	ret = nr_extents;
 	*span = 1 + highest_pblock - lowest_pblock;
 	if (cur_lblock == 0)
-		cur_lblock = 1;	/* force Empty message */
-	sis->max = cur_lblock;
-	sis->pages = cur_lblock - 1;
+		cur_lblock = blks_per_page;	/* force Empty message */
+	sis->max = cur_lblock / blks_per_page;
+	sis->pages = sis->max - 1;
 out:
 	if (not_aligned)
 		f2fs_warn(sbi, "Swapfile (%u) is not align to section: 1) creat(), 2) ioctl(F2FS_IOC_SET_PIN_FILE), 3) fallocate(%lu * N)",
-- 
2.56.0.317.g454f8302e1-goog