From: Brian Foster bfoster@redhat.com
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 paulfurtado91@gmail.com Signed-off-by: Brian Foster bfoster@redhat.com Reviewed-by: Chandan Rajendra chandanrlinux@gmail.com Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Allison Collins allison.henderson@oracle.com Reviewed-by: Darrick J. Wong darrick.wong@oracle.com Signed-off-by: Darrick J. Wong darrick.wong@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/xfs/xfs_icache.c | 10 ++++++++++ fs/xfs/xfs_ioctl.c | 5 ++++- 2 files changed, 14 insertions(+), 1 deletion(-)
--- 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); }
--- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -2264,7 +2264,10 @@ 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: