Hi, Jan
On Fri 17-03-23 09:35:53, Zhihao Cheng wrote:Following process makes i_disksize exceed i_size: generic_perform_write copied = iov_iter_copy_from_user_atomic(len) // copied < len ext4_da_write_end | ext4_update_i_disksize | new_i_size = pos + copied; | WRITE_ONCE(EXT4_I(inode)->i_disksize, newsize) // update i_disksize | generic_write_end | copied = block_write_end(copied, len) // copied = 0 | if (unlikely(copied < len)) | if (!PageUptodate(page)) | copied = 0; | if (pos + copied > inode->i_size) // return false if (unlikely(copied == 0)) goto again; if (unlikely(iov_iter_fault_in_readable(i, bytes))) { status = -EFAULT; break; } We get i_disksize greater than i_size here, which could trigger WARNING check 'i_size_read(inode) < EXT4_I(inode)->i_disksize' while doing dio: ext4_dio_write_iter iomap_dio_rw __iomap_dio_rw // return err, length is not aligned to 512 ext4_handle_inode_extension WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize) // Oops WARNING: CPU: 2 PID: 2609 at fs/ext4/file.c:319 CPU: 2 PID: 2609 Comm: aa Not tainted 6.3.0-rc2 RIP: 0010:ext4_file_write_iter+0xbc7 Call Trace: vfs_write+0x3b1 ksys_write+0x77 do_syscall_64+0x39 Fix it by putting block_write_end() before i_disksize updating just like ext4_write_end() does. Fetch a reproducer in [Link]. Link: https://bugzilla.kernel.org/show_bug.cgi?id=217209 Fixes: 64769240bd07f ("ext4: Add delayed allocation support in data=writeback mode") Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>Good catch (although practically this will hardly have any negative effect). But rather than opencoding generic_write_end() I'd do: if (unlikely(copied < len) && !PageUptodate(page)) copied = 0; at the beginning of ext4_da_write_end() and that should solve these problems as well?
Yes, your suggestion looks good, and I think we can put the checking just after ext4_write_inline_data_end(Line 3150)? On the one hand, we can pass original 'copied' value in trace_ext4_da_write_end(), one the other hand, ext4_write_inline_data_end() already has this checking.
