Hello,
I am looking into how GFS2 protects against races between hole punching and
things like page fault or readahead and AFAICT it seems it does not. In
particular is there anything that protects against a race like:
CPU1 CPU2
gfs2_fallocate()
__gfs2_punch_hole()
truncate_pagecache_range()
gfs2_fault()
- faults in old data into page
cache
punch_hole()
And now we have stale data in the page cache (data corruption). If
gfs2_page_mkwrite() sneaked in that window as well, we might be even racing
with writeback and are possibly corrupting the filesystem on disk. Is there
anything I'm missing?
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
