From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail06.adl6.internode.on.net ([150.101.137.145]:32205 "EHLO ipmail06.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751390AbeCTFA0 (ORCPT ); Tue, 20 Mar 2018 01:00:26 -0400 Received: from discord.disaster.area ([192.168.1.111]) by dastard with esmtp (Exim 4.80) (envelope-from ) id 1ey9Nm-0001tI-Fn for linux-xfs@vger.kernel.org; Tue, 20 Mar 2018 16:00:22 +1100 Received: from dave by discord.disaster.area with local (Exim 4.90_1) (envelope-from ) id 1ey9Nm-0000JC-Eh for linux-xfs@vger.kernel.org; Tue, 20 Mar 2018 16:00:22 +1100 From: Dave Chinner Subject: [PATCH 1/2] xfs: add mount delay debug option Date: Tue, 20 Mar 2018 16:00:20 +1100 Message-Id: <20180320050021.982-2-david@fromorbit.com> In-Reply-To: <20180320050021.982-1-david@fromorbit.com> References: <20180320050021.982-1-david@fromorbit.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-xfs@vger.kernel.org From: Dave Chinner Similar to log_recovery_delay, this delay occurs between the VFS superblock being initialised and the xfs_mount being fully initialised. It also poisons the per-ag radix tree node so that it can be used for triggering shrinker races during mount such as the following: $ cat dirty-mount.sh #! /bin/bash umount -f /dev/pmem0 mkfs.xfs -f /dev/pmem0 mount /dev/pmem0 /mnt/test rm -f /mnt/test/foo xfs_io -fxc "pwrite 0 4k" -c fsync -c "shutdown" /mnt/test/foo umount /dev/pmem0 # let's crash it now! echo 30 > /sys/fs/xfs/debug/mount_delay mount /dev/pmem0 /mnt/test echo 0 > /sys/fs/xfs/debug/mount_delay umount /dev/pmem0 $ sudo ./dirty-mount.sh ..... [ 60.378118] CPU: 3 PID: 3577 Comm: fs_mark Tainted: G D W 4.16.0-rc5-dgc #440 [ 60.378120] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 60.378124] RIP: 0010:radix_tree_next_chunk+0x76/0x320 [ 60.378127] RSP: 0018:ffffc9000276f4f8 EFLAGS: 00010282 [ 60.383670] RAX: a5a5a5a5a5a5a5a4 RBX: 0000000000000010 RCX: 000000000000001a [ 60.385277] RDX: 0000000000000000 RSI: ffffc9000276f540 RDI: 0000000000000000 [ 60.386554] RBP: 0000000000000000 R08: 0000000000000000 R09: a5a5a5a5a5a5a5a5 [ 60.388194] R10: 0000000000000006 R11: 0000000000000001 R12: ffffc9000276f598 [ 60.389288] R13: 0000000000000040 R14: 0000000000000228 R15: ffff880816cd6458 [ 60.390827] FS: 00007f5c124b9740(0000) GS:ffff88083fc00000(0000) knlGS:0000000000000000 [ 60.392253] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 60.393423] CR2: 00007f5c11bba0b8 CR3: 000000035580e001 CR4: 00000000000606e0 [ 60.394519] Call Trace: [ 60.395252] radix_tree_gang_lookup_tag+0xc4/0x130 [ 60.395948] xfs_perag_get_tag+0x37/0xf0 [ 60.396522] xfs_reclaim_inodes_count+0x32/0x40 [ 60.397178] xfs_fs_nr_cached_objects+0x11/0x20 [ 60.397837] super_cache_count+0x35/0xc0 [ 60.399159] shrink_slab.part.66+0xb1/0x370 [ 60.400194] shrink_node+0x7e/0x1a0 [ 60.401058] try_to_free_pages+0x199/0x470 [ 60.402081] __alloc_pages_slowpath+0x3a1/0xd20 [ 60.403729] __alloc_pages_nodemask+0x1c3/0x200 [ 60.404941] cache_grow_begin+0x20b/0x2e0 [ 60.406164] fallback_alloc+0x160/0x200 [ 60.407088] kmem_cache_alloc+0x111/0x4e0 [ 60.408038] ? xfs_buf_rele+0x61/0x430 [ 60.408925] kmem_zone_alloc+0x61/0xe0 [ 60.409965] xfs_inode_alloc+0x24/0x1d0 ..... Signed-Off-By: Dave Chinner --- fs/xfs/xfs_globals.c | 1 + fs/xfs/xfs_super.c | 12 ++++++++++++ fs/xfs/xfs_sysctl.h | 1 + fs/xfs/xfs_sysfs.c | 31 +++++++++++++++++++++++++++++++ 4 files changed, 45 insertions(+) diff --git a/fs/xfs/xfs_globals.c b/fs/xfs/xfs_globals.c index 3e1cc3001bcb..fdde17a2333c 100644 --- a/fs/xfs/xfs_globals.c +++ b/fs/xfs/xfs_globals.c @@ -47,6 +47,7 @@ xfs_param_t xfs_params = { struct xfs_globals xfs_globals = { .log_recovery_delay = 0, /* no delay by default */ + .mount_delay = 0, /* no delay by default */ #ifdef XFS_ASSERT_FATAL .bug_on_assert = true, /* assert failures BUG() */ #else diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 4944fe37fc95..ee26437dc567 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1617,6 +1617,18 @@ xfs_fs_fill_super( #endif sb->s_op = &xfs_super_operations; + /* + * Delay mount work if the debug hook is set. This is debug + * instrumention to coordinate simulation of xfs mount failures with + * VFS superblock operations + */ + if (xfs_globals.mount_delay) { + memset(&mp->m_perag_tree, 0xa5, sizeof(mp->m_perag_tree)); + xfs_notice(mp, "Delaying mount for %d seconds.", + xfs_globals.mount_delay); + msleep(xfs_globals.mount_delay * 1000); + } + if (silent) flags |= XFS_MFSI_QUIET; diff --git a/fs/xfs/xfs_sysctl.h b/fs/xfs/xfs_sysctl.h index 82afee005140..b53a33e69932 100644 --- a/fs/xfs/xfs_sysctl.h +++ b/fs/xfs/xfs_sysctl.h @@ -95,6 +95,7 @@ extern xfs_param_t xfs_params; struct xfs_globals { int log_recovery_delay; /* log recovery delay (secs) */ + int mount_delay; /* mount setup delay (secs) */ bool bug_on_assert; /* BUG() the kernel on assert failure */ }; extern struct xfs_globals xfs_globals; diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c index 8b2ccc234f36..2d5cd2529f8e 100644 --- a/fs/xfs/xfs_sysfs.c +++ b/fs/xfs/xfs_sysfs.c @@ -165,9 +165,40 @@ log_recovery_delay_show( } XFS_SYSFS_ATTR_RW(log_recovery_delay); +STATIC ssize_t +mount_delay_store( + struct kobject *kobject, + const char *buf, + size_t count) +{ + int ret; + int val; + + ret = kstrtoint(buf, 0, &val); + if (ret) + return ret; + + if (val < 0 || val > 60) + return -EINVAL; + + xfs_globals.mount_delay = val; + + return count; +} + +STATIC ssize_t +mount_delay_show( + struct kobject *kobject, + char *buf) +{ + return snprintf(buf, PAGE_SIZE, "%d\n", xfs_globals.mount_delay); +} +XFS_SYSFS_ATTR_RW(mount_delay); + static struct attribute *xfs_dbg_attrs[] = { ATTR_LIST(bug_on_assert), ATTR_LIST(log_recovery_delay), + ATTR_LIST(mount_delay), NULL, }; -- 2.16.1