On wed, 30 Jan 2013 23:55:34 -0600, Eric Sandeen wrote: >> =================================================================================== >> >> [ 7913.075890] btrfs: allowing degraded mounts >> [ 7913.075893] btrfs: disk space caching is enabled >> [ 7913.092031] Btrfs: too many missing devices, writeable mount is not >> allowed > > so this was supposed to fail the mount in open_ctree; it jumps to shutting > down > the worker threads. Which might result in no threads available. > >> [ 7913.092297] ------------[ cut here ]------------ >> [ 7913.092313] kernel BUG at fs/btrfs/async-thread.c:605! >> [ 7913.092326] invalid opcode: 0000 [#1] SMP >> [ 7913.092342] Modules linked in: btrfs zlib_deflate crc32c libcrc32c nfsd >> lockd nfs_acl auth_rpcgss sunrpc 8021q garp stp llc cpufreq_ondemand >> cachefiles fscache ipv6 ext3 jbd dm_mirror dm_region_hash dm_log dm_mod >> uinput ppdev iTCO_wdt iTCO_vendor_support parport_pc parport sg acpi_cpufreq >> freq_table mperf coretemp kvm pcspkr i2c_i801 i2c_core lpc_ich mfd_core tg3 >> ptp pps_core shpchp pci_hotplug i3000_edac edac_core ext4 mbcache jbd2 crc16 >> sr_mod cdrom sd_mod crc_t10dif pata_acpi ata_piix libata megaraid_sas >> scsi_mod floppy [last unloaded: microcode] >> [ 7913.092575] CPU 0 >> [ 7913.092584] Pid: 3673, comm: btrfs-endio-wri Not tainted 3.8.0-rc5 #1 >> FUJITSU-SV PRIMERGY /D2399 >> [ 7913.092608] RIP: 0010:[<ffffffffa04670ef>] [<ffffffffa04670ef>] >> btrfs_queue_worker+0x10e/0x236 [btrfs] > > but this is already trying to do work, and has no workers to handle it. > > The place we jump to is fail_block_groups, and before it is this comment: > > /* > * make sure we're done with the btree inode before we stop our > * kthreads > */ > filemap_write_and_wait(fs_info->btree_inode->i_mapping); > invalidate_inode_pages2(fs_info->btree_inode->i_mapping); > > fail_block_groups: > btrfs_free_block_groups(fs_info); > > if you move the fail_block_groups: target above the comment, does that fix it? > (although I don't know yet what started IO . . . )
Reading the metadata of the tree root and Reading block group information started IO. so, I think this patch can fix the problem. > like this: > > From: Eric Sandeen <sand...@redhat.com> > > Make sure that we are always done with the btree_inode's mapping > before we shut down the worker threads in open_ctree() error > cases. > > Signed-off-by: Eric Sandeen <sand...@redhat.com> > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index d89da40..1e2abda 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -2689,6 +2689,7 @@ fail_trans_kthread: > fail_cleaner: > kthread_stop(fs_info->cleaner_kthread); > > +fail_block_groups: > /* > * make sure we're done with the btree inode before we stop our > * kthreads > @@ -2696,7 +2697,6 @@ fail_cleaner: > filemap_write_and_wait(fs_info->btree_inode->i_mapping); > invalidate_inode_pages2(fs_info->btree_inode->i_mapping); > > -fail_block_groups: > btrfs_free_block_groups(fs_info); > > fail_tree_roots: > > Just a guess; but I don't know what would have started writes already... I don't think it was write IO. It was just a soft interrupt caused by a metadata read IO, and this soft interrupt happened while btrfs-endio-write-workers was going to stop. Thanks Miao -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
