On Mon, Oct 12 2009 at 2:15pm -0400, Theodore Ts'o <tytso@xxxxxxx> wrote: > Hi, I'm trying to track down a problem relating to ext4 problems, in > kernel bugzilla 14354. Originally it was thought this was a regression > 2.6.31->2.6.32-rc1 regression, but the Aneesh Kumar's report shows a > very similar fsck transcript using a 2.6.30-1 kernel (which makes makes > it unclear whether this is really a regression or not), and all three > reports are tied together by the use of device-mapper. > > The fsck logs are consistent barriers being disabled. As I recall under > some circumstances device mapper silently drops barrier requests --- I > thought this was fixed for device mapper in some cases. What's the > current status of barrier requests in device mapper? Are they > faithfully passed for standard (non-RAID) LVM2 volumes? When was this > changed? What about dm-crypto volumes? (One of the reports was with a > dm-crypt volume from what I can tell.) Barrier infrastructure started to get added to the DM core in 2.6.30, see: http://git.kernel.org/linus/af7e466a1ace But barriers were not enabled for all DM targets (_except_ dm-multipath) until 2.6.31. So 2.6.31's dm-crypt does support barriers, see: http://git.kernel.org/linus/647c7db14ef9 If the underlying device(s) support barriers DM should faithfully pass them on (again except for dm-multipath). Also, requests with barriers that result in -EOPNOTSUPP are retried without the barrier, see: http://git.kernel.org/linus/51aa32284958 Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
