Btrfs: fix BUG_ON() caused by ENOSPC when relocating space
When we balanced the chunks across the devices, BUG_ON() in __finish_chunk_alloc() was triggered. ------------[ cut here ]------------ kernel BUG at fs/btrfs/volumes.c:2568! [SNIP] Call Trace: [<ffffffffa049525e>] btrfs_alloc_chunk+0x8e/0xa0 [btrfs] [<ffffffffa04546b0>] do_chunk_alloc+0x330/0x3a0 [btrfs] [<ffffffffa045c654>] btrfs_reserve_extent+0xb4/0x1f0 [btrfs] [<ffffffffa045c86b>] btrfs_alloc_free_block+0xdb/0x350 [btrfs] [<ffffffffa048a8d8>] ? read_extent_buffer+0xd8/0x1d0 [btrfs] [<ffffffffa04476fd>] __btrfs_cow_block+0x14d/0x5e0 [btrfs] [<ffffffffa044660d>] ? read_block_for_search+0x14d/0x4d0 [btrfs] [<ffffffffa0447c9b>] btrfs_cow_block+0x10b/0x240 [btrfs] [<ffffffffa044dd5e>] btrfs_search_slot+0x49e/0x7a0 [btrfs] [<ffffffffa044f07d>] btrfs_insert_empty_items+0x8d/0xf0 [btrfs] [<ffffffffa045e973>] insert_with_overflow+0x43/0x110 [btrfs] [<ffffffffa045eb0d>] btrfs_insert_dir_item+0xcd/0x1f0 [btrfs] [<ffffffffa0489bd0>] ? map_extent_buffer+0xb0/0xc0 [btrfs] [<ffffffff812276ad>] ? rb_insert_color+0x9d/0x160 [<ffffffffa046cc40>] ? inode_tree_add+0xf0/0x150 [btrfs] [<ffffffffa0474801>] btrfs_add_link+0xc1/0x1c0 [btrfs] [<ffffffff811dacac>] ? security_inode_init_security+0x1c/0x30 [<ffffffffa04a28aa>] ? btrfs_init_acl+0x4a/0x180 [btrfs] [<ffffffffa047492f>] btrfs_add_nondir+0x2f/0x70 [btrfs] [<ffffffffa046af16>] ? btrfs_init_inode_security+0x46/0x60 [btrfs] [<ffffffffa0474ac0>] btrfs_create+0x150/0x1d0 [btrfs] [<ffffffff81159c63>] ? generic_permission+0x23/0xb0 [<ffffffff8115b415>] vfs_create+0xa5/0xc0 [<ffffffff8115ce6e>] do_last+0x5fe/0x880 [<ffffffff8115dc0d>] path_openat+0xcd/0x3d0 [<ffffffff8115e029>] do_filp_open+0x49/0xa0 [<ffffffff8116a965>] ? alloc_fd+0x95/0x160 [<ffffffff8114f0c7>] do_sys_open+0x107/0x1e0 [<ffffffff810bcc3f>] ? audit_syscall_entry+0x1bf/0x1f0 [<ffffffff8114f1e0>] sys_open+0x20/0x30 [<ffffffff81484ec2>] system_call_fastpath+0x16/0x1b [SNIP] RIP [<ffffffffa049444a>] __finish_chunk_alloc+0x20a/0x220 [btrfs] The reason is: Task1 Space balance task do_chunk_alloc() __finish_chunk_alloc() update device info in the chunk tree alloc system metadata block relocate system metadata block group set system metadata block group readonly, This block group is the only one that can allocate space. So there is no free space that can be allocated now. find no space and don't try to alloc new chunk, and then return ENOSPC BUG_ON() in __finish_chunk_alloc() was triggered. Fix this bug by allocating a new system metadata chunk before relocating the old one if we find there is no free space which can be allocated after setting the old block group to be read-only. Reported-by:Tsutomu Itoh <t-itoh@jp.fujitsu.com> Signed-off-by:
Miao Xie <miaox@cn.fujitsu.com> Tested-by:
Tsutomu Itoh <t-itoh@jp.fujitsu.com> Signed-off-by:
Chris Mason <chris.mason@oracle.com>
parent
f7aaa06b
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