Messages in this thread | | | Date | Tue, 5 Nov 2002 08:42:18 -0700 | From | Andreas Dilger <> | Subject | Re: [Q] How to flush disk cache w/read-only filesystem w/o unmount&remount? (shared SAN filesystem) |
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On Nov 05, 2002 10:18 -0500, Jim Lawson wrote: > I'm looking for a way to flush or invalidate the cache on the block > device/filesystem, so that the system is forced to go all the way to the > disk. Unmounting and remounting would accomplish this, of course, but > that's tough to do in production. > > I've tried blockdev --flushbufs, which appears to do a BLKFLSBUF, but that > seems to be equivalent to "sync" - just pushes the dirty buffers to disk, > which doesn't help me. > > Looking in fs/dcache.c, I see shrink_dcache_sb(struct super_block *), > which *might* do what I want, but there doesn't seem to be any way to call > that from user-land. And that probably just updates the dentries - I > don't know if that has any effect on the file data.
You may be in luck - we likely need to have an ioctl to do this from e2fsck because the ext3 htree repacking of bad directories is causing a bunch of problems. In theory, the startup scripts should reboot the system in this case, but there have also been cases reported where people ran "e2fsck -D" on an ro-mounted root and then read-write mounted it again.
Cheers, Andreas -- Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto, \ would they cancel out, leaving him still hungry?" http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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