From 4d0bab3a44686f26be7ee7295c6c1987605ae35e Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Wed, 1 Jul 2020 10:21:28 -0700 Subject: xfs: remove SYNC_WAIT from xfs_reclaim_inodes() Clean up xfs_reclaim_inodes() callers. Most callers want blocking behaviour, so just make the existing SYNC_WAIT behaviour the default. For the xfs_reclaim_worker(), just call xfs_reclaim_inodes_ag() directly because we just want optimistic clean inode reclaim to be done in the background. For xfs_quiesce_attr() we can just remove the inode reclaim calls as they are a historic relic that was required to flush dirty inodes that contained unlogged changes. We now log all changes to the inodes, so the sync AIL push from xfs_log_quiesce() called by xfs_quiesce_attr() will do all the required inode writeback for freeze. Seeing as we now want to loop until all reclaimable inodes have been reclaimed, make xfs_reclaim_inodes() loop on the XFS_ICI_RECLAIM_TAG tag rather than having xfs_reclaim_inodes_ag() tell it that inodes were skipped. This is much more reliable and will always loop until all reclaimable inodes are reclaimed. Signed-off-by: Dave Chinner Reviewed-by: Darrick J. Wong Reviewed-by: Brian Foster Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_super.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'fs/xfs/xfs_super.c') diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 379cbff438bc..5a5d9453cf51 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -890,9 +890,6 @@ xfs_quiesce_attr( /* force the log to unpin objects from the now complete transactions */ xfs_log_force(mp, XFS_LOG_SYNC); - /* reclaim inodes to do any IO before the freeze completes */ - xfs_reclaim_inodes(mp, 0); - xfs_reclaim_inodes(mp, SYNC_WAIT); /* Push the superblock and write an unmount record */ error = xfs_log_sbcount(mp); -- cgit From c3f2375b90d0d26f257b926a0d236371df483ca1 Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Wed, 8 Jul 2020 10:21:44 -0700 Subject: xfs: Fix false positive lockdep warning with sb_internal & fs_reclaim Depending on the workloads, the following circular locking dependency warning between sb_internal (a percpu rwsem) and fs_reclaim (a pseudo lock) may show up: ====================================================== WARNING: possible circular locking dependency detected 5.0.0-rc1+ #60 Tainted: G W ------------------------------------------------------ fsfreeze/4346 is trying to acquire lock: 0000000026f1d784 (fs_reclaim){+.+.}, at: fs_reclaim_acquire.part.19+0x5/0x30 but task is already holding lock: 0000000072bfc54b (sb_internal){++++}, at: percpu_down_write+0xb4/0x650 which lock already depends on the new lock. : Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_internal); lock(fs_reclaim); lock(sb_internal); lock(fs_reclaim); *** DEADLOCK *** 4 locks held by fsfreeze/4346: #0: 00000000b478ef56 (sb_writers#8){++++}, at: percpu_down_write+0xb4/0x650 #1: 000000001ec487a9 (&type->s_umount_key#28){++++}, at: freeze_super+0xda/0x290 #2: 000000003edbd5a0 (sb_pagefaults){++++}, at: percpu_down_write+0xb4/0x650 #3: 0000000072bfc54b (sb_internal){++++}, at: percpu_down_write+0xb4/0x650 stack backtrace: Call Trace: dump_stack+0xe0/0x19a print_circular_bug.isra.10.cold.34+0x2f4/0x435 check_prev_add.constprop.19+0xca1/0x15f0 validate_chain.isra.14+0x11af/0x3b50 __lock_acquire+0x728/0x1200 lock_acquire+0x269/0x5a0 fs_reclaim_acquire.part.19+0x29/0x30 fs_reclaim_acquire+0x19/0x20 kmem_cache_alloc+0x3e/0x3f0 kmem_zone_alloc+0x79/0x150 xfs_trans_alloc+0xfa/0x9d0 xfs_sync_sb+0x86/0x170 xfs_log_sbcount+0x10f/0x140 xfs_quiesce_attr+0x134/0x270 xfs_fs_freeze+0x4a/0x70 freeze_super+0x1af/0x290 do_vfs_ioctl+0xedc/0x16c0 ksys_ioctl+0x41/0x80 __x64_sys_ioctl+0x73/0xa9 do_syscall_64+0x18f/0xd23 entry_SYSCALL_64_after_hwframe+0x49/0xbe This is a false positive as all the dirty pages are flushed out before the filesystem can be frozen. One way to avoid this splat is to add GFP_NOFS to the affected allocation calls by using the memalloc_nofs_save()/memalloc_nofs_restore() pair. This shouldn't matter unless the system is really running out of memory. In that particular case, the filesystem freeze operation may fail while it was succeeding previously. Without this patch, the command sequence below will show that the lock dependency chain sb_internal -> fs_reclaim exists. # fsfreeze -f /home # fsfreeze --unfreeze /home # grep -i fs_reclaim -C 3 /proc/lockdep_chains | grep -C 5 sb_internal After applying the patch, such sb_internal -> fs_reclaim lock dependency chain can no longer be found. Because of that, the locking dependency warning will not be shown. Suggested-by: Dave Chinner Signed-off-by: Waiman Long Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_super.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'fs/xfs/xfs_super.c') diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 5a5d9453cf51..5ef5d8416f70 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -910,11 +910,21 @@ xfs_fs_freeze( struct super_block *sb) { struct xfs_mount *mp = XFS_M(sb); + unsigned int flags; + int ret; + /* + * The filesystem is now frozen far enough that memory reclaim + * cannot safely operate on the filesystem. Hence we need to + * set a GFP_NOFS context here to avoid recursion deadlocks. + */ + flags = memalloc_nofs_save(); xfs_stop_block_reaping(mp); xfs_save_resvblks(mp); xfs_quiesce_attr(mp); - return xfs_sync_sb(mp, true); + ret = xfs_sync_sb(mp, true); + memalloc_nofs_restore(flags); + return ret; } STATIC int -- cgit From 4750a171c3290f9bbebca16c6372db723a4cfa3b Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Wed, 15 Jul 2020 08:30:37 -0700 Subject: xfs: preserve inode versioning across remounts The MS_I_VERSION mount flag is exposed via the VFS, as documented in the mount manpages etc; see the iversion and noiversion mount options in mount(8). As a result, mount -o remount looks for this option in /proc/mounts and will only send the I_VERSION flag back in during remount it it is present. Since it's not there, a remount will /remove/ the I_VERSION flag at the vfs level, and iversion functionality is lost. xfs v5 superblocks intend to always have i_version enabled; it is set as a default at mount time, but is lost during remount for the reasons above. The generic fix would be to expose this documented option in /proc/mounts, but since that was rejected, fix it up again in the xfs remount path instead, so that at least xfs won't suffer from this misbehavior. Signed-off-by: Eric Sandeen Reviewed-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Darrick J. Wong Reviewed-by: Darrick J. Wong --- fs/xfs/xfs_super.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs/xfs/xfs_super.c') diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 5ef5d8416f70..71ac6c1cdc36 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1721,6 +1721,10 @@ xfs_fc_reconfigure( int flags = fc->sb_flags; int error; + /* version 5 superblocks always support version counters. */ + if (XFS_SB_VERSION_NUM(&mp->m_sb) == XFS_SB_VERSION_5) + fc->sb_flags |= SB_I_VERSION; + error = xfs_fc_validate_params(new_mp); if (error) return error; -- cgit