Hi, Liu
> Removing large amount of block group in a transaction may encounters
> BUG_ON() in btrfs_orphan_add(). That is becuase
> btrfs_orphan_reserve_metadata()
Not big matter,
s/becuase/because
Thanks
Zhaolei
> will grab metadata reservation from transaction handle, and
> btrfs_delete_unused_bgs() didn't reserve metadata for trnasaction handle when
> delete unused block group.
>
> The problem can be reproduce by following script
>
> mntpath=/btrfs
> loopdev=/dev/loop0
> filepath=/home/forrest/image
>
> umount $mntpath
> losetup -d $loopdev
> truncate --size 1000g $filepath
> losetup $loopdev $filepath
> mkfs.btrfs -f $loopdev
> mount $loopdev $mntpath
>
> for j in `seq 1 1 1000`; do
> fallocate -l 1g $mntpath/$j
> done
> # wait cleaner thread remove unused block group
> sleep 300
>
> The call trace that results from the BUG_ON() is:
>
> [ 613.093084] ------------[ cut here ]------------
> [ 613.097928] kernel BUG at fs/btrfs/inode.c:3142!
> [ 613.105855] invalid opcode: 0000 [#1] SMP
> [ 613.112702] Modules linked in: coretemp(E) crc32_pclmul(E)
> ghash_clmulni_intel(E) aesni_intel(E) snd_ens1371(E)
snd_ac97_codec(E)
> aes_x86_64(E) lrw(E) gf128mul(E) glue_helper(E) ppdev(E) ac97_bus(E)
> ablk_helper(E) gameport(E) cryptd(E) snd_rawmidi(E)
> snd_seq_device(E) snd_pcm(E) vmw_balloon(E) snd_timer(E) snd(E) soundcore(E)
> serio_raw(E) vmwgfx(E) ttm(E) drm_kms_helper(E)
drm(E)
> vmw_vmci(E) parport_pc(E) shpchp(E) i2c_piix4(E) mac_hid(E) lp(E) parport(E)
> btrfs(E) xor(E) raid6_pq(E) hid_generic(E) usbhid(E)
hid(E)
> psmouse(E) ahci(E) libahci(E) e1000(E) mptspi(E) mptscsih(E) mptbase(E)
> floppy(E) vmw_pvscsi(E) vmxnet3(E)
> [ 613.144196] CPU: 0 PID: 1480 Comm: btrfs-cleaner Tainted: G E
> 3.19.0-rc7-custom #2
> [ 613.148501] Hardware name: VMware, Inc. VMware Virtual Platform/440BX
> Desktop Reference Platform, BIOS 6.00 07/31/2013
> [ 613.152694] task: ffff880035cdb1a0 ti: ffff880039cf4000 task.ti:
> ffff880039cf4000
> [ 613.154969] RIP: 0010:[<ffffffffa01441c2>] [<ffffffffa01441c2>]
> btrfs_orphan_add+0x1d2/0x1e0 [btrfs]
> [ 613.157780] RSP: 0018:ffff880039cf7c48 EFLAGS: 00010286
> [ 613.159560] RAX: 00000000ffffffe4 RBX: ffff88003bd981a0 RCX:
> ffff88003c9e4000
> [ 613.161904] RDX: 0000000000002244 RSI: 0000000000040000 RDI:
> ffff88003c9e4138
> [ 613.164264] RBP: ffff880039cf7c88 R08: 000060ffc0000850 R09:
> 0000000000000000
> [ 613.166507] R10: ffff88003bc4b7a0 R11: ffffea0000eb6740 R12:
> ffff88003c9c0000
> [ 613.168681] R13: ffff88003c102160 R14: ffff88003c9c0458 R15:
> 0000000000000001
> [ 613.170932] FS: 0000000000000000(0000) GS:ffff88003f600000(0000)
> knlGS:0000000000000000
> [ 613.173316] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 613.175227] CR2: 00007f6343537000 CR3: 0000000036329000 CR4:
> 00000000000407f0
> [ 613.177554] Stack:
> [ 613.178712] ffff880039cf7c88 ffffffffa0182a54 ffff88003c9e4b04
> ffff88003c9c7800
> [ 613.181297] ffff88003bc4b7a0 ffff88003bd981a0 ffff88003c8db200
> ffff88003c2fcc60
> [ 613.183782] ffff880039cf7d18 ffffffffa012da97 ffff88003bc4b7a4
> ffff88003bc4b7a0
> [ 613.186171] Call Trace:
> [ 613.187493] [<ffffffffa0182a54>] ? lookup_free_space_inode+0x44/0x100
> [btrfs]
> [ 613.189801] [<ffffffffa012da97>] btrfs_remove_block_group+0x137/0x740
> [btrfs]
> [ 613.192126] [<ffffffffa0166912>] btrfs_remove_chunk+0x672/0x780 [btrfs]
> [ 613.194267] [<ffffffffa012e2ff>] btrfs_delete_unused_bgs+0x25f/0x280
> [btrfs]
> [ 613.196567] [<ffffffffa0135e4c>] cleaner_kthread+0x12c/0x190 [btrfs]
> [ 613.198687] [<ffffffffa0135d20>] ? check_leaf+0x350/0x350 [btrfs]
> [ 613.200758] [<ffffffff8108f232>] kthread+0xd2/0xf0
> [ 613.202616] [<ffffffff8108f160>] ? kthread_create_on_node+0x180/0x180
> [ 613.204738] [<ffffffff8175dabc>] ret_from_fork+0x7c/0xb0
> [ 613.206652] [<ffffffff8108f160>] ? kthread_create_on_node+0x180/0x180
> [ 613.208741] Code: ff ff 0f 1f 80 00 00 00 00 89 45 c8 3e 80 63 80 fd 48 89
> df e8 d0 23 fe ff 8b 45 c8 e9 14 ff ff ff b8 f4 ff
ff ff e9 12 ff ff ff <0f>
> 0b 66 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 55 48
> [ 613.216562] RIP [<ffffffffa01441c2>] btrfs_orphan_add+0x1d2/0x1e0 [btrfs]
> [ 613.218828] RSP <ffff880039cf7c48>
> [ 613.220382] ---[ end trace 71073106deb8a457 ]---
>
> This patch replace btrfs_join_transaction() with btrfs_start_transaction() in
> btrfs_delete_unused_bgs() to revent BUG_ON() in btrfs_orphan_add()
>
> Signed-off-by: Forrest Liu <forre...@synology.com>
> ---
> V2: add reproducing step and call trace in commit message
>
> fs/btrfs/extent-tree.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index a684086..63b974f 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -9611,7 +9611,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info
> *fs_info)
> * Want to do this before we do anything else so we can recover
> * properly if we fail to join the transaction.
> */
> - trans = btrfs_join_transaction(root);
> + /* 1 for btrfs_orphan_reserve_metadata() */
> + trans = btrfs_start_transaction(root, 1);
> if (IS_ERR(trans)) {
> btrfs_set_block_group_rw(root, block_group);
> ret = PTR_ERR(trans);
> --
> 1.9.1
>
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