On Fri, Sep 09, 2016 at 11:37:21PM +0200, Hans van Kranenburg wrote: > Hi, > > While trying to enable skinny metadata on a filesystem, I got this error > (after minutes of reading from disk by the program): > > -# btrfstune -x /dev/xvdb > extent-tree.c:2688: btrfs_reserve_extent: Assertion `ret` failed. > btrfstune[0x410ef6] > btrfstune[0x410f1d] > btrfstune(btrfs_reserve_extent+0x781)[0x41522e] > btrfstune(btrfs_alloc_free_block+0x63)[0x415413] > btrfstune(__btrfs_cow_block+0xfc)[0x409176] > btrfstune(btrfs_cow_block+0x8b)[0x409718] > btrfstune[0x40d8ad] > btrfstune(btrfs_commit_transaction+0xb8)[0x40f10d] > btrfstune(main+0x3b3)[0x407e31] > /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f945fa06700] > btrfstune(_start+0x29)[0x408509] > > This is a ~40TiB filesystem that was created about one and a half year > ago, has grown from 1TiB to this size now and has always been running > with the Debian 3.16-ckt kernel. > > # uname -a > Linux backups-dolly 4.7.0-1-amd64 #1 SMP Debian 4.7.2-1 (2016-08-28) > x86_64 GNU/Linux > > # btrfs version > btrfs-progs v4.7.1 > > One of the things I already did earlier today was switching to > space_cache=v2 > > Does the shown error ring a bell? What's the next step to debug this? It's a bug in the incompat bit handling the free-space-tree. Opening the filesystem for read-write should not be allowed, but was mistakenly enabled by me. > The filesystem is a clone of the production filesystem (not btrfs clone, > but lower level, on iSCSI storage) meant to be used for upgrade-testing > and performance testing, so if anything goes wrong in whatever way, > there will be no panicing involved. The fix is in devel, but it'd mean that writing to a v2-enabled filesystem will not work (which also means changing some fatures via btrfstune as it uses the transaction mechanism that needs to cow blocks and update free space etc). -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
