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From:   Daeho Jeong <daeho43@gmail.com>
To:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com
Cc:     Daeho Jeong <daehojeong@google.com>
Subject: [PATCH] f2fs: use cow inode data when updating atomic write
Date:   Tue, 18 Apr 2023 10:52:06 -0700
Message-ID: <20230418175206.3282328-1-daeho43@gmail.com>
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From: Daeho Jeong <daehojeong@google.com>

Need to use cow inode data content instead of the one in the original
inode, when we try to write the already updated atomic write files.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
 fs/f2fs/data.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 8df225014304..7165b1202f53 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3491,7 +3491,7 @@ static int __reserve_data_block(struct inode *inode, pgoff_t index,
 
 static int prepare_atomic_write_begin(struct f2fs_sb_info *sbi,
 			struct page *page, loff_t pos, unsigned int len,
-			block_t *blk_addr, bool *node_changed)
+			block_t *blk_addr, bool *node_changed, bool *use_cow)
 {
 	struct inode *inode = page->mapping->host;
 	struct inode *cow_inode = F2FS_I(inode)->cow_inode;
@@ -3505,10 +3505,12 @@ static int prepare_atomic_write_begin(struct f2fs_sb_info *sbi,
 
 	/* Look for the block in COW inode first */
 	err = __find_data_block(cow_inode, index, blk_addr);
-	if (err)
+	if (err) {
 		return err;
-	else if (*blk_addr != NULL_ADDR)
+	} else if (*blk_addr != NULL_ADDR) {
+		*use_cow = true;
 		return 0;
+	}
 
 	if (is_inode_flag_set(inode, FI_ATOMIC_REPLACE))
 		goto reserve_block;
@@ -3538,6 +3540,7 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 	struct page *page = NULL;
 	pgoff_t index = ((unsigned long long) pos) >> PAGE_SHIFT;
 	bool need_balance = false;
+	bool use_cow = false;
 	block_t blkaddr = NULL_ADDR;
 	int err = 0;
 
@@ -3597,7 +3600,7 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 
 	if (f2fs_is_atomic_file(inode))
 		err = prepare_atomic_write_begin(sbi, page, pos, len,
-					&blkaddr, &need_balance);
+					&blkaddr, &need_balance, &use_cow);
 	else
 		err = prepare_write_begin(sbi, page, pos, len,
 					&blkaddr, &need_balance);
@@ -3637,7 +3640,9 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 			f2fs_handle_error(sbi, ERROR_INVALID_BLKADDR);
 			goto fail;
 		}
-		err = f2fs_submit_page_read(inode, page, blkaddr, 0, true);
+		err = f2fs_submit_page_read(use_cow ?
+				F2FS_I(inode)->cow_inode : inode, page,
+				blkaddr, 0, true);
 		if (err)
 			goto fail;
 
-- 
2.40.0.634.g4ca3ef3211-goog