On Mon, Feb 18, 2013 at 05:53:50PM +0100, Stefan Behrens wrote:
> On Sat, 16 Feb 2013 14:47:45 +0800, Liu Bo wrote:
> > What about this patch(UNTESTED)?
> >
> > thanks,
> > liubo
> >
> > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> > index ca7ace7..dac9d4b 100644
> > --- a/fs/btrfs/inode.c
> > +++ b/fs/btrfs/inode.c
> > @@ -4142,9 +4142,14 @@ static void inode_tree_del(struct inode *inode)
> > * root_refs of 0, so this could end up dropping the tree root as a
> > * snapshot, so we need the extra !root->fs_info->tree_root check to
> > * make sure we don't drop it.
> > + *
> > + * Inode cache's inodes may be iput and add root back to dead roots
> > + * list during killing super, which leads to use-after-free, so
> > + * we need to check fs_info->closing to keep us from use-after-free.
> > */
> > if (empty && btrfs_root_refs(&root->root_item) == 0 &&
> > - root != root->fs_info->tree_root) {
> > + root != root->fs_info->tree_root &&
> > + btrfs_fs_closing(root->fs_info) > 1) {
> > synchronize_srcu(&root->fs_info->subvol_srcu);
> > spin_lock(&root->inode_lock);
> > empty = RB_EMPTY_ROOT(&root->inode_tree);
>
> No improvement with this patch. The inode_cache causes a crash in __list_add.
> I tested it on the latest cmason/for-linus with and without your patch.
Ahh, I think I made a finger error,
+ btrfs_fs_closing(root->fs_info) > 1) {
SHOULD be
+ btrfs_fs_closing(root->fs_info) < 2) {
>
> This script is an 100% reproducer on my test box:
> mkfs.btrfs -d single -m raid1 /dev/sdc /dev/sdj /dev/sds /dev/sdt /dev/sdu
> /dev/sdv
> mount /dev/sdc /mnt -o compress=lzo,space_cache,inode_cache
> btrfs subv create /mnt/src
> (cd ~/git/btrfs/fs/btrfs && tar cf - .) | (cd /mnt/src && tar xf -)
> for i in `seq 2000`; do btrfs subv create /mnt/${i}; (cd /mnt/src && tar cf -
> .) | (cd /mnt/${i} && tar xf -); done
> for i in /mnt/[0-9]*; do btrfs subv dele ${i}; done
> sleep 45
> umount /mnt
With the latest cmason/for-linus(commit 6f60cbd3ae442cb35861bb522f388db123d42ec1
btrfs: access superblock via pagecache in scan_one_device),
I ran this script several times with all good, I used two 40G disks,
others remains same.
I'm wondering which line does 'del_fs_roots+0xaf/0xf0 [btrfs]' refer to?
thanks,
liubo
>
> BUG: unable to handle kernel paging request at ffff88023517d830
> IP: [<ffffffff814415f7>] __list_add+0x17/0xd0
> PGD 1e0c063 PUD bf58e067 PMD bf737067 PTE 800000023517d160
> Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> Modules linked in: btrfs raid1 mpt2sas scsi_transport_sas raid_class
> CPU 2
> Pid: 18503, comm: umount Not tainted 3.7.0+ #44 Supermicro X8SIL/X8SIL
> RIP: 0010:[<ffffffff814415f7>] [<ffffffff814415f7>] __list_add+0x17/0xd0
> RSP: 0018:ffff88019e1abbd8 EFLAGS: 00010286
> RAX: ffff8802353aa290 RBX: ffff880229e38828 RCX: 0000000000000001
> RDX: ffff88023517d828 RSI: ffff8802327214c0 RDI: ffff880229e38828
> RBP: ffff88019e1abbf8 R08: 000000000006e130 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000001 R12: ffff880229e38000
> R13: ffff880229e38898 R14: 0000000000000000 R15: ffff88019e1abd30
> FS: 00007f75eabc4740(0000) GS:ffff880236a00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: ffff88023517d830 CR3: 000000019e17e000 CR4: 00000000000007e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process umount (pid: 18503, threadinfo ffff88019e1aa000, task
> ffff8802353aa290)
> Stack:
> ffffffffa008619f ffff880229e38000 ffff880229e38000 ffff880229e38898
> ffff88019e1abc18 ffffffffa00861c0 ffff88012760dc38 ffff88012760dc38
> ffff88019e1abc48 ffffffffa0095358 ffff88012760dc38 ffff88012760dcc0
> Call Trace:
> [<ffffffffa008619f>] ? btrfs_add_dead_root+0x1f/0x60 [btrfs]
> [<ffffffffa00861c0>] btrfs_add_dead_root+0x40/0x60 [btrfs]
> [<ffffffffa0095358>] btrfs_destroy_inode+0x1d8/0x2d0 [btrfs]
> [<ffffffff811af9c7>] destroy_inode+0x37/0x60
> [<ffffffff811afafd>] evict+0x10d/0x1a0
> [<ffffffff811b02a5>] iput+0x105/0x190
> [<ffffffffa007dda8>] free_fs_root+0x18/0x90 [btrfs]
> [<ffffffffa00811eb>] btrfs_free_fs_root+0x7b/0x90 [btrfs]
> [<ffffffffa00812af>] del_fs_roots+0xaf/0xf0 [btrfs]
> [<ffffffffa0082c16>] close_ctree+0x1c6/0x300 [btrfs]
> [<ffffffff811b072c>] ? evict_inodes+0xec/0x100
> [<ffffffffa00583a4>] btrfs_put_super+0x14/0x20 [btrfs]
> [<ffffffff8119805c>] generic_shutdown_super+0x5c/0xe0
> [<ffffffff81198171>] kill_anon_super+0x11/0x20
> [<ffffffffa005c3a5>] btrfs_kill_super+0x15/0x90 [btrfs]
> [<ffffffff811991a1>] ? deactivate_super+0x41/0x70
> [<ffffffff8119856d>] deactivate_locked_super+0x3d/0x70
> [<ffffffff811991a9>] deactivate_super+0x49/0x70
> [<ffffffff811b4332>] mntput_no_expire+0xd2/0x130
> [<ffffffff811b52e1>] sys_umount+0x71/0x390
> [<ffffffff81956992>] system_call_fastpath+0x16/0x1b
>
>
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