From: Alex Elder Date: Thu, 1 Nov 2012 15:17:15 +0000 (-0500) Subject: rbd: add a warning in bio_chain_clone_range() X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f5400b7a0e78a53edce8960a079aa022640849a1;p=linux-beck.git rbd: add a warning in bio_chain_clone_range() Add a warning in bio_chain_clone_range() to help a user determine what exactly might have led to a failure. There is only one; please say something if you disagree with the following reasoning. There are three places this can return abnormally: - Initially, if there is nothing to clone. It turns out that right now this cannot happen anyway. The test is in place because the code below it doesn't work if those conditions don't hold. As such they could be assertions but since I can return a null to indicate an error I just do that instead. I have not added a warning here because it won't happen. - While processing bio's, if none remain but there are supposed to be more bytes to clone. Here I have added a warning. - If bio_clone_range() returns a null pointer. That function will have already produced a warning (at least the first time, via WARN_ON_ONCE()) to distinguish the cause of the error. The only exception is memory exhaustion, and I'd rather not pepper the code with warnings in all those spots. So no warning is added in that place. Signed-off-by: Alex Elder Reviewed-by: Josh Durgin --- diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 31da8c538480..ce6c0cbb3d7a 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -993,8 +993,10 @@ static struct bio *bio_chain_clone_range(struct bio **bio_src, unsigned int bi_size; struct bio *bio; - if (!bi) + if (!bi) { + rbd_warn(NULL, "bio_chain exhausted with %u left", len); goto out_err; /* EINVAL; ran out of bio's */ + } bi_size = min_t(unsigned int, bi->bi_size - off, len); bio = bio_clone_range(bi, off, bi_size, gfpmask); if (!bio)