On 4/28/14, 6:26 PM, Theodore Ts'o wrote: > On Mon, Apr 28, 2014 at 10:33:40AM -0500, Eric Sandeen wrote: >> On 4/26/14, 7:00 PM, Theodore Ts'o wrote: >>> If mke2fs needs to ask the user for permission, and the user doesn't >>> type anything for five seconds, proceed as if the user had said yes. >>> >>> This will allow us to add more stringent checks without breaking >>> existing scripts (much). >> >> Hm, this sounds a little dangerous - "-F" overrides a lot. > > Actually, if you take a look at what we use proceed_question() for, it > doesn't actually override anything (up until now) that might lead to > data loss. It's for things like trying to create an file system with > a block size greater than 4k on an x86 platform, creating a file > system larger than the apparent block size, etc. The main goal was to > make sure the user actually *sees* the darned message. > > Perhaps the only case where proceed_question() can prevent data loss > is the one where the user typo's /dev/sda3 as /dev/sda. Everything > else is in the category of "we want to make sure the user sees the > warning". > > The motivation behind this is adding this safety check: > > % ./misc/mke2fs -t ext4 -L test-filesystem /dev/sdc3 8M > mke2fs 1.42.9 (4-Feb-2014) > /dev/sdc3 contains a ext4 file system labelled 'test-filesystem' > Proceed anyway (or wait 5 seconds) ? (y,n) > > Previously, we would blithely blow away /dev/sdc3 without even giving > a warning. So if stdin (fd 0) is not a tty, we skip this test > entirely --- otherwise existing scripts would fail. However, if a > script is attached to a tty, we would end up stalling the script > waiting for the user to answer yes/no where previously no question > would be asked at all. This is the case where it's important that > proceed_question() will now pause five seconds, and then continue. I guess it's up to you, but it gives me the heebie-jeebies. xfs and btrfs already stop on an existing fs (or a partition table) unless the script adds the force option. Stopping to make sure about an irreversible action - but proceeding after 5s anyway - seems to me like the worst of both worlds. If it doesn't matter, don't ask. If it matters, wait for a response, however long it might take. At least that's my take on it. :) -Eric > - Ted > -- 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
