On 2011-04-25, at 2:23 PM, Curt Wohlgemuth wrote: > In the bio completion routine, we should not be setting > PageUptodate at all -- it's set at sys_write() time, and is > unaffected by success/failure of the write to disk. > > This can cause a page corruption bug when > > block size < page size > > @@ -203,46 +203,29 @@ static void ext4_end_bio(struct bio *bio, int error) > - /* > - * If this is a partial write which happened to make > - * all buffers uptodate then we can optimize away a > - * bogus readpage() for the next read(). Here we > - * 'discover' whether the page went uptodate as a > - * result of this (potentially partial) write. > - */ > - if (!partial_write) > - SetPageUptodate(page); > - I think this is the important part of the code - if there is a read-after-write for a file that was written in "blocksize" units (blocksize < pagesize), does the page get set uptodate when all of the blocks have been written and/or the writing is at EOF? Otherwise, a read-after-write will always cause data to be fetched from disk needlessly, even though the uptodate information is already in cache. Cheers, Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
