On 02/26/2015 01:43 AM, Dave Chinner wrote: > On Wed, Feb 25, 2015 at 06:31:15PM -0500, Brian Foster wrote: >> On Thu, Feb 26, 2015 at 09:32:48AM +1100, Dave Chinner wrote: >>> [cc linux-fsdevel, Boaz and others] >>> >>> On Wed, Feb 25, 2015 at 11:11:51AM -0500, Brian Foster wrote: >>>> On Wed, Feb 25, 2015 at 09:54:36AM +1100, Dave Chinner wrote: >>>>> From: Dave Chinner <dchinner@xxxxxxxxxx> >>>>> >>>>> xfs/104, xfs/119, xfs/291 and xfs/297 have small fixed log sizes. A >>>>> recent change to the kernel ramdisk changed it's physical sector >>>>> size from 512B to 4kB, and this results in mkfs calculating a log >>>>> size larger than the fixed test size and hence the tests fail. >>>>> >>>>> Change the log size to a larger size that works with 4k sectors, and >>>>> also increase the size of the filesystem being created so that the >>>>> amount of data space in the filesystem does not change and hence >>>>> does not perturb the rest of the test. >>>>> >>>>> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> >>>>> --- >>>> >>>> Well for some reason I can't mount a ramdisk on the current tot to test >>>> this. In fact, I can't mount _anything_ after the ramdisk mount attempt. >>>> The mount actually reports success too, but there's nothing there... :/ >>>> >>>> # modprobe brd >>>> # mkfs.xfs -f /dev/ram0 >>>> meta-data=/dev/ram0 isize=256 agcount=1, agsize=4096 >>>> blks >>>> = sectsz=4096 attr=2, projid32bit=1 >>>> = crc=0 finobt=0 >>>> data = bsize=4096 blocks=4096, imaxpct=25 >>>> = sunit=0 swidth=0 blks >>>> naming =version 2 bsize=4096 ascii-ci=0 ftype=0 >>>> log =internal log bsize=4096 blocks=1605, version=2 >>>> = sectsz=4096 sunit=1 blks, lazy-count=1 >>>> realtime =none extsz=4096 blocks=0, rtextents=0 >>>> # mount /dev/ram0 /mnt/ >>>> # mount | grep mnt >>>> # umount /mnt/ >>>> umount: /mnt/: not mounted >>>> >>>> ... and then I can't even mount my normal scratch device until after a >>>> reboot: >>>> >>>> # mount /dev/test/scratch /mnt/ >>>> # mount | grep mnt >>>> # umount /mnt/ >>>> umount: /mnt/: not mounted >>> >>> Ok, so that's just plain broken. What's in dmesg? >>> >> >> Once I got back to this I found that for some reason systemd is >> immediately invoking a umount on the mount. :/ No idea why or how to >> stop it, but if I do something like this: >> >> mount /dev/ram0 /mnt; cd /mnt >> >> ... I can occasionally win the race and get systemd to spin in a >> umount() cycle trying to undo the mount. I haven't gone back to confirm >> it's the same behavior with the normal devices at that point, but I >> suspect it is, perhaps due to getting into some kind of bad state. >> >> So fyi that this particular problem doesn't appear to be directly kernel >> related... > > It may still be related to the kernel changes e.g. by triggering > udev events when they didn't previously. The only machine I have > that is triggering the partition probing is also the only test > machine that I have that runs systemd and it didn't have this > problem on 3.19. > Sigh, thanks Dave. Yes you are correct my patch enabled the udev events, as part of fixing ramdisk with partitions. This is because if you do not enable them then mount by UUID and all sort of lsblk and friends do not work. I did try to test this in all kind of ways, xfstest+ext4 as well, and ran with it on Fedora 20 for a while, sorry about that. It looks like the system anticipates that ramdisk "should not have these events" I will send a patch ASAP that re-instates the module_parameter for enabling notification, and leaving the default off. It should be easy to set the param if one intends to use these utilities. That said, please do agree with me that there is brokenness in systemd? BTW: You also said something about the 4k sectors thing, It looks like we are pulled in two different directions here. If you will want to use DAX on ramdisk then you want it on, if you are not using DAX, and wants to use smaller-then-page_size FS blocks than you do not want it. Please advise what we should do? Maybe only do 4k if BLK_DEV_RAM_DAX is set in Kconfig ? Sorry for the mess, I'll send a fix ASAP > Cheers, > Dave. > Thanks Boaz -- 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
