From: Yongpeng Yang <[email protected]>

Neither F2FS nor VFS invalidates the block device page cache, which
results in reading stale metadata. An example scenario is shown below:

Terminal A                  Terminal B
mount /dev/vdb /mnt/f2fs
touch mx // ino = 4
sync
dump.f2fs -i 4 /dev/vdb// block on "[Y/N]"
                            touch mx2 // ino = 5
                            sync
                            umount /mnt/f2fs
                            dump.f2fs -i 5 /dev/vdb // block addr is 0

After umount, the block device page cache is not purged, causing
`dump.f2fs -i 5 /dev/vdb` to read stale metadata and see inode 5 with
block address 0.

This patch calls invalidate_bdev during umount to invalidate the block
device page cache, preventing stale metadata from being read.

Signed-off-by: Yongpeng Yang <[email protected]>
---
 fs/f2fs/super.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 1a755997aff5..39d3b52ceac1 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2091,6 +2091,12 @@ static void f2fs_put_super(struct super_block *sb)
 #if IS_ENABLED(CONFIG_UNICODE)
        utf8_unload(sb->s_encoding);
 #endif
+       sync_blockdev(sb->s_bdev);
+       invalidate_bdev(sb->s_bdev);
+       for (i = 1; i < sbi->s_ndevs; i++) {
+               sync_blockdev(FDEV(i).bdev);
+               invalidate_bdev(FDEV(i).bdev);
+       }
 }
 
 int f2fs_sync_fs(struct super_block *sb, int sync)
-- 
2.52.0



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