Hi, how to test the patch?

Hi,
"ext4: fix races between page faults and hole punching"

can you tell me how to test the patch? Thank you very much.

-Ai Hua

Hi,

Well, it is not really easy to test for (which is why I haven't written an xfstest for that) :). You can prepare a some zeroed file, mmap it, and read it through mmap while puching holes into the file and also randomly filling holes back while writing zeroes. When there is some other activity in the filesystem allocating blocks and writing to them some data, you may see this data instead of zeros in the mmap if the bug triggers.

If you create a successful reproducer, please let me know and consider contributing it to xfstests so that we can check the behavior.

Honza

Jan Kara <[email protected]>
SUSE Labs, CR