Sage Weil <sage@xxxxxxxxxxxx> writes: > The ceph address space methods are concerned primarily with managing > the dirty page accounting in the inode, which (among other things) > must keep track of which snapshot context each page was dirtied in, > and ensure that dirty data is written out to the OSDs in snapshort > order. > > A writepage() on a page that is not currently writeable due to > snapshot writeback ordering constraints is ignored (it was presumably > called from kswapd). Not a detailed review. You would need to get one from someone who knows the VFS interfaces very well (unfortunately those people are hard to find). I just read through it. One thing I noticed is that you seem to do a lot of memory allocation in the write out paths (some of it even GFP_KERNEL, not GFP_NOFS) The traditional wisdom is that you should not allocate memory in block writeout, because that can deadlock. The worst case is swapfile on it, but it can happen with mmap too (e.g. one process using most memory with a file mmap from your fs) GFP_KERNEL can also recurse, which can cause other problems in your fs. There were some changes to make this problem less severe (e.g. better dirty pages accounting), but I don't think anyone has really declared it solved yet. The standard workaround for this is to use mempools for anything allocated in the writeout path, then you are at least guaranteed to make forward progress. You also had at least one unchecked kmalloc I think. -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
