Messages in this thread | | | Date | Sun, 29 Jun 2008 23:37:31 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [xfs-masters] Re: freeze vs freezer |
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Dave Chinner wrote: > On Mon, Jun 30, 2008 at 01:22:47AM +0200, Rafael J. Wysocki wrote: > >> On Monday, 30 of June 2008, Dave Chinner wrote: >> >>> On Thu, Jun 26, 2008 at 05:09:10PM +0200, Pavel Machek wrote: >>> >>>>>> Is this the same thing the per-device IO-queue-freeze patches for >>>>>> HDAPS also >>>>>> need to do? If so, you may want to talk to Elias Oltmanns >>>>>> <eo@nebensachen.de> about it. Added to CC. >>>>>> >>>>> Thanks for the heads up Henrique. Even though these issues seem to be >>>>> related up to a certain degree, there probably are some important >>>>> differences. When suspending a system, the emphasis is on leaving the >>>>> system in a consistent state (think of journalled file systems), whereas >>>>> disk shock protection is mainly concerned with stopping I/O as soon as >>>>> possible. As yet, I cannot possibly say to what extend these two >>>>> concepts can be reconciled in the sense of sharing some common code. >>>>> >>>> Actually, I believe requirements are same. >>>> >>>> 'don't do i/o in dangerous period'. >>>> >>>> swsusp will just do sync() before entering dangerous period. That >>>> provides consistent-enough state... >>>> >>> As I've said many times before - if the requirement is "don't do >>> I/O" then you have to freeze the filesystem. In no way does 'sync' >>> prevent filesystems from doing I/O..... >>> >> Well, it seems we can handle this on the block layer level, by temporarily >> replacing the elevator with something that will selectively prevent fs I/O >> from reaching the layers below it. >> > > Why? What part of freeze_bdev() doesn't work for you?
Well, my original problem - which is still an issue - is that a process writing to a frozen XFS filesystem is stuck in D state, and therefore cannot be frozen as part of suspend.
J
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