Messages in this thread Patch in this message | | | Date | Sun, 7 Apr 2013 06:21:27 +0400 | Subject | Re: mkfs.f2fs gets stuck with "blk_update_request: bio idx 0 >= vcnt 0" on 3.8 | From | Max Filippov <> |
| |
On Sun, Apr 7, 2013 at 5:58 AM, Shaohua Li <shli@kernel.org> wrote: > On Fri, Apr 05, 2013 at 06:18:10AM +0400, Max Filippov wrote: >> On Fri, Apr 5, 2013 at 5:53 AM, Shaohua Li <shli@kernel.org> wrote: >> > On Thu, Apr 04, 2013 at 06:00:18AM +0400, Max Filippov wrote: >> >> [...] >> >> >> the commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9 'block: add plug >> >> for blkdev_issue_discard' >> >> have added merge opportunity for DISCARD requests. When I do >> >> mkfs.f2fs on a 5G partition (0xad8000 sectors) it submits two bios, >> >> one for 0x7fe000 sectors (0xffc00000 bytes) and another for >> >> 0x2da000 sectors (0x5b400000 bytes). Prior to that commit these >> >> bios weren't merged into one request. Now the second bio gets >> >> merged with the first, but the request's __data_len field is unsigned int >> >> and it gets wrapped to 0x5b000000 bytes instead of 0x15b000000 >> >> in the bio_attempt_back_merge. Later this reduced size is passed to >> >> the blk_update_request causing KERN_ERR and not completed >> >> request. Reverting this commit fixes mkfs.f2fs for me. >> > >> > A workaround is setting limits.max_discard_sectors to a smaller value. >> >> I'm not sure: >> 1) in my case max_discard_sectors is 0x7fe000 (0xffc00000 bytes, >> which still fits into 32 bits) and >> 2) this parameter will only change size of individual discard requests for >> the discarded range, but as long as these requests are done inside >> the plug they will be merged anyway with an overflow if we try >> to discard more than 4G at once. > > No, merge in plug list checks max_discard_sectors. Please see > ll_back_merge_fn() in bio_attempt_back_merge(). Merge in unplug checks > max_discard_sectors too. I didn't see any chance a merge doesn't check > max_discard_sectors. Can you post a blktrace when the discard ioctl runs and > double check if max_discard_sectors is really 0x7fe000?
Ok, max_discard_sectors is a bit ambiguous here. There's a variable inside blkdev_issue_discard called max_discard_sectors, I looked at it and it was 0x7fe000. But the q->limits.max_discard_sectors is initialized to 0xffffffff in the mmc_queue_setup_discard. The following change fixes the original issue too:
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index aaed768..0753986 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -1920,7 +1920,7 @@ unsigned int mmc_calc_max_discard(struct mmc_card *card) unsigned int max_discard, max_trim;
if (!host->max_discard_to) - return UINT_MAX; + return UINT_MAX >> 9;
/* * Without erase_group_def set, MMC erase timeout depends on clock
-- Thanks. -- Max
| |