This patch + the fix to add/remove links on the respective device
operation seem to work with the previous test that used to catch the
slab corruptions, so far so good.
After this has been running fine for a few hours, I've tried to do a
simple check
# cd /sys/fs/btrfs
# find . -type f -exec cat '{}' \;
that produced this lockdep warning:
[ 4943.485655] run xfstest btrfs/004
[ 4944.053971] BTRFS: device fsid 6b90f3ce-cd83-44da-88e2-c89a4607b782 devid 1 transid 4 /dev/sda9
[ 4944.067637] BTRFS info (device sda9): disk space caching is enabled
[ 4944.075621] BTRFS: flagging fs with big metadata feature
[ 4944.093954] BTRFS: creating UUID tree
[ 4950.077597] BTRFS info (device sda9): setting 8 feature flag
[ 4950.084961] BTRFS info (device sda9): disk space caching is enabled
[ 4952.992993]
[ 4952.996020] ======================================================
[ 4952.996020] [ INFO: possible circular locking dependency detected ]
[ 4952.996020] 3.15.0-rc7-default+ #146 Tainted: G W
[ 4952.996020] -------------------------------------------------------
[ 4952.996020] cat/3822 is trying to acquire lock:
[ 4952.996020] (&found->groups_sem){++++..}, at: [<ffffffffa004babe>] raid_bytes_show+0x3e/0xd0 [btrfs]
[ 4952.996020]
[ 4952.996020] but task is already holding lock:
[ 4952.996020] (s_active#149){++++.+}, at: [<ffffffff811ef1c9>] kernfs_seq_start+0x39/0xb0
[ 4952.996020]
[ 4952.996020] which lock already depends on the new lock.
[ 4952.996020]
[ 4952.996020]
[ 4952.996020] the existing dependency chain (in reverse order) is:
[ 4952.996020]
-> #1 (s_active#149){++++.+}:
[ 4952.996020] [<ffffffff810b0662>] lock_acquire+0x92/0x120
[ 4952.996020] [<ffffffff811edc07>] __kernfs_remove+0x2b7/0x380
[ 4952.996020] [<ffffffff811ee787>] kernfs_remove+0x27/0x40
[ 4952.996020] [<ffffffff811f0b3a>] sysfs_remove_dir+0x5a/0x90
[ 4952.996020] [<ffffffff813ba028>] kobject_del+0x18/0x90
[ 4952.996020] [<ffffffffa0023cb2>] btrfs_remove_block_group+0x442/0x580 [btrfs]
[ 4952.996020] [<ffffffffa005caf4>] btrfs_relocate_chunk+0x624/0x770 [btrfs]
[ 4952.996020] [<ffffffffa005f652>] btrfs_balance+0x902/0xf50 [btrfs]
[ 4952.996020] [<ffffffffa006b090>] btrfs_ioctl_balance+0x1e0/0x350 [btrfs]
[ 4952.996020] [<ffffffffa006d4a9>] btrfs_ioctl+0xc39/0x1830 [btrfs]
[ 4952.996020] [<ffffffff8118c381>] do_vfs_ioctl+0x91/0x560
[ 4952.996020] [<ffffffff8118c8a3>] SyS_ioctl+0x53/0x80
[ 4952.996020] [<ffffffff81a16cd2>] system_call_fastpath+0x16/0x1b
[ 4952.996020]
-> #0 (&found->groups_sem){++++..}:
[ 4952.996020] [<ffffffff810afc5c>] __lock_acquire+0x1c4c/0x1fa0
[ 4952.996020] [<ffffffff810b0662>] lock_acquire+0x92/0x120
[ 4952.996020] [<ffffffff81a0bedc>] down_read+0x4c/0xa0
[ 4952.996020] [<ffffffffa004babe>] raid_bytes_show+0x3e/0xd0 [btrfs]
[ 4952.996020] [<ffffffff813b9ef6>] kobj_attr_show+0x16/0x20
[ 4952.996020] [<ffffffff811f04e9>] sysfs_kf_seq_show+0xd9/0x230
[ 4952.996020] [<ffffffff811eec56>] kernfs_seq_show+0x26/0x30
[ 4952.996020] [<ffffffff8119ec8f>] seq_read+0xef/0x410
[ 4952.996020] [<ffffffff811efa35>] kernfs_fop_read+0x125/0x180
[ 4952.996020] [<ffffffff81179fe4>] vfs_read+0xb4/0x180
[ 4952.996020] [<ffffffff8117a269>] SyS_read+0x59/0xd0
[ 4952.996020] [<ffffffff81a16cd2>] system_call_fastpath+0x16/0x1b
[ 4952.996020]
[ 4952.996020] other info that might help us debug this:
[ 4952.996020]
[ 4952.996020] Possible unsafe locking scenario:
[ 4952.996020]
[ 4952.996020] CPU0 CPU1
[ 4952.996020] ---- ----
[ 4952.996020] lock(s_active#149);
[ 4952.996020] lock(&found->groups_sem);
[ 4952.996020] lock(s_active#149);
[ 4952.996020] lock(&found->groups_sem);
[ 4952.996020]
[ 4952.996020] *** DEADLOCK ***
[ 4952.996020]
[ 4952.996020] 3 locks held by cat/3822:
[ 4952.996020] #0: (&p->lock){+.+.+.}, at: [<ffffffff8119ebdf>] seq_read+0x3f/0x410
[ 4952.996020] #1: (&of->mutex){+.+.+.}, at: [<ffffffff811ef1c1>] kernfs_seq_start+0x31/0xb0
[ 4952.996020] #2: (s_active#149){++++.+}, at: [<ffffffff811ef1c9>] kernfs_seq_start+0x39/0xb0
[ 4952.996020]
[ 4952.996020] stack backtrace:
[ 4952.996020] CPU: 0 PID: 3822 Comm: cat Tainted: G W 3.15.0-rc7-default+ #146
[ 4952.996020] Hardware name: Intel Corporation Santa Rosa platform/Matanzas, BIOS TSRSCRB1.86C.0047.B00.0610170821 10/17/06
[ 4952.996020] ffffffff82828a50 ffff880065aedb88 ffffffff81a07898 0000000000000001
[ 4952.996020] ffffffff82821230 ffff880065aedbd8 ffffffff810acb74 00000000001d4500
[ 4952.996020] ffff880065aedc58 0000000000000002 ffff880066ab2c08 0000000000000002
[ 4952.996020] Call Trace:
[ 4952.996020] [<ffffffff81a07898>] dump_stack+0x51/0x71
[ 4952.996020] [<ffffffff810acb74>] print_circular_bug+0x214/0x310
[ 4952.996020] [<ffffffff810afc5c>] __lock_acquire+0x1c4c/0x1fa0
[ 4952.996020] [<ffffffffa004babe>] ? raid_bytes_show+0x3e/0xd0 [btrfs]
[ 4952.996020] [<ffffffff810b0662>] lock_acquire+0x92/0x120
[ 4952.996020] [<ffffffffa004babe>] ? raid_bytes_show+0x3e/0xd0 [btrfs]
[ 4952.996020] [<ffffffff81a0bedc>] down_read+0x4c/0xa0
[ 4952.996020] [<ffffffffa004babe>] ? raid_bytes_show+0x3e/0xd0 [btrfs]
[ 4952.996020] [<ffffffff810aa37f>] ? __lock_is_held+0x5f/0x80
[ 4952.996020] [<ffffffffa004babe>] raid_bytes_show+0x3e/0xd0 [btrfs]
[ 4952.996020] [<ffffffff813b9ef6>] kobj_attr_show+0x16/0x20
[ 4952.996020] [<ffffffff811f04e9>] sysfs_kf_seq_show+0xd9/0x230
[ 4952.996020] [<ffffffff811eec56>] kernfs_seq_show+0x26/0x30
[ 4952.996020] [<ffffffff8119ec8f>] seq_read+0xef/0x410
[ 4952.996020] [<ffffffff811efa35>] kernfs_fop_read+0x125/0x180
[ 4952.996020] [<ffffffff8117941e>] ? rw_verify_area+0xe/0xc0
[ 4952.996020] [<ffffffff81179fe4>] vfs_read+0xb4/0x180
[ 4952.996020] [<ffffffff8117a269>] SyS_read+0x59/0xd0
[ 4952.996020] [<ffffffff81a16cd2>] system_call_fastpath+0x16/0x1b
--
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