On Tue, Mar 09, 2021 at 10:23:35AM +0800, Weichao Guo wrote:

Hi Richard,

On 2021/3/8 19:53, Richard Palethorpe wrote:

quoted

Hello,

quoted

kern  :err   : [  187.461914] F2FS-fs (sda1): Swapfile does not align to section
commit 02eb84b96bc1b382dd138bf60724edbefe77b025
Author: huangjianan@oppo.com [off-list ref]
Date:   Mon Mar 1 12:58:44 2021 +0800
     f2fs: check if swapfile is section-alligned
     If the swapfile isn't created by pin and fallocate, it can't be
     guaranteed section-aligned, so it may be selected by f2fs gc. When
     gc_pin_file_threshold is reached, the address of swapfile may change,
     but won't be synchronized to swap_extent, so swap will write to wrong
     address, which will cause data corruption.
     Signed-off-by: Huang Jianan [off-list ref]
     Signed-off-by: Guo Weichao [off-list ref]
     Reviewed-by: Chao Yu [off-list ref]
     Signed-off-by: Jaegeuk Kim [off-list ref]

The test uses fallocate to preallocate the swap file and writes zeros to
it. I'm not sure what pin refers to?

'pin' refers to pinned file feature in F2FS, the LBA(Logical Block Address)
of a file is fixed after pinned. Without this operation before fallocate,
the LBA may not align with section(F2FS GC unit), some LBA of the file may
be changed by F2FS GC in some extreme cases.

For this test case, how about pin the swap file before fallocate for F2FS as
following:

ioctl(fd, F2FS_IOC_SET_PIN_FILE, true);

No special ioctl should be needed.  f2fs_swap_activate() should pin the
file, just like it converts inline inodes and disables compression.