From ccd3b4bb9944f0538884d7396246273d8361996d Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Sun, 12 Apr 2020 13:11:10 -0700 Subject: [PATCH] xfs: acquire superblock freeze protection on eofblocks scans commit 4b674b9ac852937af1f8c62f730c325fb6eadcdb upstream. The filesystem freeze sequence in XFS waits on any background eofblocks or cowblocks scans to complete before the filesystem is quiesced. At this point, the freezer has already stopped the transaction subsystem, however, which means a truncate or cowblock cancellation in progress is likely blocked in transaction allocation. This results in a deadlock between freeze and the associated scanner. Fix this problem by holding superblock write protection across calls into the block reapers. Since protection for background scans is acquired from the workqueue task context, trylock to avoid a similar deadlock between freeze and blocking on the write lock. Fixes: d6b636ebb1c9f ("xfs: halt auto-reclamation activities while rebuilding rmap") Reported-by: Paul Furtado Signed-off-by: Brian Foster Reviewed-by: Chandan Rajendra Reviewed-by: Christoph Hellwig Reviewed-by: Allison Collins Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_icache.c | 10 ++++++++++ fs/xfs/xfs_ioctl.c | 5 ++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index 944add5..d95dc9b 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -907,7 +907,12 @@ xfs_eofblocks_worker( { struct xfs_mount *mp = container_of(to_delayed_work(work), struct xfs_mount, m_eofblocks_work); + + if (!sb_start_write_trylock(mp->m_super)) + return; xfs_icache_free_eofblocks(mp, NULL); + sb_end_write(mp->m_super); + xfs_queue_eofblocks(mp); } @@ -934,7 +939,12 @@ xfs_cowblocks_worker( { struct xfs_mount *mp = container_of(to_delayed_work(work), struct xfs_mount, m_cowblocks_work); + + if (!sb_start_write_trylock(mp->m_super)) + return; xfs_icache_free_cowblocks(mp, NULL); + sb_end_write(mp->m_super); + xfs_queue_cowblocks(mp); } diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 2a19093..c93c4b7 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -2401,7 +2401,10 @@ xfs_file_ioctl( if (error) return error; - return xfs_icache_free_eofblocks(mp, &keofb); + sb_start_write(mp->m_super); + error = xfs_icache_free_eofblocks(mp, &keofb); + sb_end_write(mp->m_super); + return error; } default: -- 2.7.4