Hi all, I test a scenario that will cause the difference of inode blocks between client and host, the scenario as follows:
Precondition: 1) use VirtFS(virtio-9p) to connect guest and host. 2) 9p dir in guest is /mnt/9p, host is /9p-host. 3) server fs is ext4 and block size is 4096. Test steps: 1) on the client(guest) # touch /mnt/9p/test/file # dd if=/dev/zero of=/mnt/9p/test/file bs=1 count=1043456 seek=1302528 conv=notrunc 2) on the client(guest) # stat /mnt/9p/test/file the file's blocks is 4582 blocks(block size is 512) 3) on the server(host) # stat /9p-host/test/file the file's blocks is 2040 blocks(block size is 512) Cause analysis: Because the file is sparse file, so in function v9fs_write_end will update inode blocks according to difference between last_pos and inode_size, only when last_pos is larger than the inode_size, then it update the blocks and inode_size, the operation is not fit the sparse file. Currently I want to call v9fs_invalidate_inode_attr to invalidate inode, but it will influence the performance, so I don't have a good solution. Please advise. Thanks in advance! Best regards, Yiwen
