On 03/08/2013 12:23 AM, Lukáš Czerner wrote: > On Thu, 7 Mar 2013, Stephen Warren wrote: > >> Date: Thu, 07 Mar 2013 12:47:09 -0700 >> From: Stephen Warren <swarren@xxxxxxxxxxxxx> >> To: Lukáš Czerner <lczerner@xxxxxxxxxx> >> Cc: Theodore Ts'o <tytso@xxxxxxx>, Chris Ball <cjb@xxxxxxxxxx>, >> linux-ext4@xxxxxxxxxxxxxxx, Stephen Warren <swarren@xxxxxxxxxx> >> Subject: Re: [PATCH] mke2fs: restore verbose message for BLKDISCARD >> >> On 03/06/2013 12:13 AM, Lukáš Czerner wrote: >>> On Tue, 5 Mar 2013, Stephen Warren wrote: >>> >>>> Date: Tue, 5 Mar 2013 13:25:18 -0700 >>>> From: Stephen Warren <swarren@xxxxxxxxxxxxx> >>>> To: Theodore Ts'o <tytso@xxxxxxx> >>>> Cc: Chris Ball <cjb@xxxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx, >>>> Stephen Warren <swarren@xxxxxxxxxx> >>>> Subject: [PATCH] mke2fs: restore verbose message for BLKDISCARD >>>> >>>> From: Stephen Warren <swarren@xxxxxxxxxx> >>>> >>>> mke2fs on a large slow eMMC device may appear to hang while executing >>>> ioctl(BLKDISCARD). CTRL-C and CTRL-\ don't appear to respond, or respond >>>> extremely slowly. -v doesn't give any hints what's happening. Only strace >>>> is a clue. Make -v print some clues to make it easier to track down the >>>> apparent hang. >>>> >>>> This change re-uses the original messages that were implemented as part >>>> of 5827d24 "mke2fs support for BLKDISCARD" in order to easily re-use the >>>> translations of that message. Note that this patch prints the first >>>> message before executing the IOCTL, so the user is told what's going on >>>> before the long wait. >>>> >>>> Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx> >>> >>> Note that you've added the message only around the first 4k discard >>> which is only used to test whether the device actually support the >>> discard... which is not very useful and it can not even know whether >>> the whole device discard will succeed/fail so it is misleading. >> >> Oops. I certainly should looked at the code better. >> >>> Moreover there actually is a message saying that we're "Discarding >>> device blocks" and it even shows the progress. The step in which >>> we're doing the discard (and update the progress) is given by >>> DISCARD_STEP_MB = 2048MB. And all that in non verbose mode as well. >> >> That said, it's that very first call to io_channel_discard() that is >> hanging then; I don't see the existing message at all. With my change, I >> do see the new message that I added. (So, no stdio flushing issue here). > > It's just one fs block discard, are you sure about that ? Yes: root@localhost:~# strace -e ioctl ./e2fsprogs/misc/mke2fs -v /dev/mmcblk1p1 mke2fs 1.43-WIP (21-Jan-2013) ioctl(3, BLKGETSIZE64, 0xbe940110) = 0 fs_types for mke2fs.conf resolution: 'ext2' ioctl(3, BLKSSZGET, 0xbe940360) = 0 ioctl(3, BLKPBSZGET, 0xbe940364) = 0 ioctl(3, BLKDISCARDZEROES, 0xbe940324) = 0 ioctl(3, BLKROGET, 0xbe940324) = 0 Calling BLKDISCARD from 0 to 4096 ioctl(3, BLKDISCARD >> I will go investigate why this API is hanging. Sorry for the noise. -- 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
