[PATCH 11/20] f2fs: support subpage blocks in move range

[Daeho Jeong <daeho43@gmail.com>]

From: Daeho Jeong <daehojeong@google.com>

Folios at both ends of the moved ranges can straddle the range
boundaries. Write back and truncate the page cache from PAGE_SIZE
boundaries, and hold invalidate_lock of both inodes during the exchange
so that faults and readahead cannot bring back stale data. The page
cache was not truncated before, so this also applies when the block
size equals PAGE_SIZE. Remove the -EOPNOTSUPP check.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
 fs/f2fs/file.c | 45 +++++++++++++++++++++++++++++++--------------
 1 file changed, 31 insertions(+), 14 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 3ef810653bb2..0fad86267256 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3501,17 +3501,6 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in,
 	if (ret)
 		goto out_unlock;
 
-	/* write out all dirty pages from offset */
-	ret = filemap_write_and_wait_range(src->i_mapping,
-					pos_in, pos_in + len);
-	if (ret)
-		goto out_unlock;
-
-	ret = filemap_write_and_wait_range(dst->i_mapping,
-					pos_out, pos_out + len);
-	if (ret)
-		goto out_unlock;
-
 	f2fs_balance_fs(sbi, true);
 
 	f2fs_down_write(&F2FS_I(src)->i_gc_rwsem[WRITE]);
@@ -3521,6 +3510,31 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in,
 			goto out_src;
 	}
 
+	/*
+	 * Hold invalidate_lock across writeback, truncation and the block
+	 * exchange so neither faults nor readahead can repopulate the page
+	 * cache with pre-exchange data.
+	 */
+	filemap_invalidate_lock_two(src->i_mapping, dst->i_mapping);
+
+	/* write out all dirty pages from offset */
+	ret = filemap_write_and_wait_range(src->i_mapping,
+					round_down(pos_in, PAGE_SIZE),
+					round_up(pos_in + len, PAGE_SIZE) - 1);
+	if (ret)
+		goto out_inval;
+
+	ret = filemap_write_and_wait_range(dst->i_mapping,
+					round_down(pos_out, PAGE_SIZE),
+					round_up(pos_out + len, PAGE_SIZE) - 1);
+	if (ret)
+		goto out_inval;
+
+	truncate_pagecache_range(src, round_down(pos_in, PAGE_SIZE),
+				 round_up(pos_in + len, PAGE_SIZE) - 1);
+	truncate_pagecache_range(dst, round_down(pos_out, PAGE_SIZE),
+				 round_up(pos_out + len, PAGE_SIZE) - 1);
+
 	f2fs_lock_op(sbi, &lc);
 	ret = __exchange_data_block(src, dst, F2FS_BYTES_TO_BLK(sbi, pos_in),
 				F2FS_BYTES_TO_BLK(sbi, pos_out),
@@ -3534,6 +3548,12 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in,
 	}
 	f2fs_unlock_op(sbi, &lc);
 
+	/* the exchange may have extended dst past its old EOF folio */
+	if (i_size_read(dst) > dst_osize)
+		pagecache_isize_extended(dst, dst_osize, i_size_read(dst));
+out_inval:
+	filemap_invalidate_unlock_two(src->i_mapping, dst->i_mapping);
+
 	if (src != dst)
 		f2fs_up_write(&F2FS_I(dst)->i_gc_rwsem[WRITE]);
 out_src:
@@ -3588,9 +3608,6 @@ static int f2fs_ioc_move_range(struct file *filp, unsigned long arg)
 {
 	struct f2fs_move_range range;
 
-	if (f2fs_has_subpage_blocks(F2FS_I_SB(file_inode(filp))))
-		return -EOPNOTSUPP;
-
 	if (copy_from_user(&range, (struct f2fs_move_range __user *)arg,
 							sizeof(range)))
 		return -EFAULT;
-- 
2.56.0.317.g454f8302e1-goog