Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes: > On Sat, 14 May 2016 00:25:28 +0800 Eryu Guan <guaneryu@xxxxxxxxx> wrote: > >> Currently direct writes inside i_size on a DIO_SKIP_HOLES filesystem are >> not allowed to allocate blocks(get_more_blocks() sets 'create' to 0 >> before calling get_block() callback), if it's a sparse file, direct >> writes fall back to buffered writes to avoid stale data exposure from >> concurrent buffered read. But there're two cases that can result in >> stale data exposure are not correctly detected. >> >> 1. The detection for "writing inside i_size" is not sufficient, writes >> can be treated as "extending writes" wrongly. For example, direct write >> 1FSB to a 1FSB sparse file on ext2/3/4, starting from offset 0, in this >> case it's writing inside i_size, but 'create' is non-zero, because >> 'block_in_file' and '(i_size_read(inode) >> blkbits' are both zero. > > um, what is an "FSB"? File System Block, as opposed to a block device block. :) -Jeff -- 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
