[PATCH] f2fs: fix to read source block before invalidating it

[Jaegeuk Kim]

f2fs_allocate_data_block() invalidates old block address and enable new block
address. Then, if we try to read old block by f2fs_submit_page_bio(), it will
give WARN due to reading invalid blocks.

Let's make the order sanely back.

Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
 fs/f2fs/gc.c | 57 ++++++++++++++++++++++++++++------------------------
 1 file changed, 31 insertions(+), 26 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 6691f526fa40..35c5453ab874 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -740,6 +740,7 @@ static int move_data_block(struct inode *inode, block_t bidx,
 	block_t newaddr;
 	int err = 0;
 	bool lfs_mode = test_opt(fio.sbi, LFS);
+	bool submitted = false;
 
 	/* do not read out */
 	page = f2fs_grab_cache_page(inode->i_mapping, bidx, false);
@@ -796,6 +797,20 @@ static int move_data_block(struct inode *inode, block_t bidx,
 	if (lfs_mode)
 		down_write(&fio.sbi->io_order_lock);
 
+	mpage = f2fs_grab_cache_page(META_MAPPING(fio.sbi),
+			fio.old_blkaddr, false);
+	if (!mpage)
+		goto put_out;
+
+	if (!PageUptodate(mpage)) {
+		err = f2fs_submit_page_bio(&fio);
+		if (err) {
+			f2fs_put_page(mpage, 1);
+			goto put_out;
+		}
+		submitted = true;
+	}
+
 	f2fs_allocate_data_block(fio.sbi, NULL, fio.old_blkaddr, &newaddr,
 					&sum, CURSEG_COLD_DATA, NULL, false);
 
@@ -803,44 +818,34 @@ static int move_data_block(struct inode *inode, block_t bidx,
 				newaddr, FGP_LOCK | FGP_CREAT, GFP_NOFS);
 	if (!fio.encrypted_page) {
 		err = -ENOMEM;
-		goto recover_block;
-	}
-
-	mpage = f2fs_pagecache_get_page(META_MAPPING(fio.sbi),
-					fio.old_blkaddr, FGP_LOCK, GFP_NOFS);
-	if (mpage) {
-		bool updated = false;
-
-		if (PageUptodate(mpage)) {
-			memcpy(page_address(fio.encrypted_page),
-					page_address(mpage), PAGE_SIZE);
-			updated = true;
-		}
 		f2fs_put_page(mpage, 1);
-		invalidate_mapping_pages(META_MAPPING(fio.sbi),
-					fio.old_blkaddr, fio.old_blkaddr);
-		if (updated)
-			goto write_page;
+		goto recover_block;
 	}
 
-	err = f2fs_submit_page_bio(&fio);
-	if (err)
-		goto put_page_out;
-
-	/* write page */
-	lock_page(fio.encrypted_page);
+	if (!submitted)
+		goto write_page;
 
-	if (unlikely(fio.encrypted_page->mapping != META_MAPPING(fio.sbi))) {
+	/* read source block */
+	lock_page(mpage);
+	if (unlikely(mpage->mapping != META_MAPPING(fio.sbi))) {
 		err = -EIO;
+		f2fs_put_page(mpage, 1);
 		goto put_page_out;
 	}
-	if (unlikely(!PageUptodate(fio.encrypted_page))) {
+	if (unlikely(!PageUptodate(mpage))) {
 		err = -EIO;
+		f2fs_put_page(mpage, 1);
 		goto put_page_out;
 	}
-
 write_page:
+	/* write target block */
 	f2fs_wait_on_page_writeback(fio.encrypted_page, DATA, true, true);
+	memcpy(page_address(fio.encrypted_page),
+				page_address(mpage), PAGE_SIZE);
+	f2fs_put_page(mpage, 1);
+	invalidate_mapping_pages(META_MAPPING(fio.sbi),
+				fio.old_blkaddr, fio.old_blkaddr);
+
 	set_page_dirty(fio.encrypted_page);
 	if (clear_page_dirty_for_io(fio.encrypted_page))
 		dec_page_count(fio.sbi, F2FS_DIRTY_META);
-- 
2.19.0.605.g01d371f741-goog