Re: [PATCH] xfs: don't call into blockgc scan with freeze protection
From: "Darrick J. Wong" <djwong@kernel.org>
Date: 2021-02-19 03:24:00
On Thu, Feb 18, 2021 at 03:14:58PM -0500, Brian Foster wrote:
fstest xfs/167 produced a lockdep splat that complained about a nested transaction acquiring freeze protection during an eofblocks scan. Drop freeze protection around the block reclaim scan in the transaction allocation code to avoid this problem. Signed-off-by: Brian Foster <redacted>
I think it seems reasonable, though I really wish that other patchset to clean up all the "modify thread state when we start/end transactions" had landed. Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D
quoted hunk ↗ jump to hunk
--- fs/xfs/xfs_trans.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index 44f72c09c203..c32c62d3b77a 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c@@ -261,6 +261,7 @@ xfs_trans_alloc( { struct xfs_trans *tp; int error; + bool retried = false; /* * Allocate the handle before we do our freeze accounting and setting up@@ -288,19 +289,27 @@ xfs_trans_alloc( INIT_LIST_HEAD(&tp->t_dfops); tp->t_firstblock = NULLFSBLOCK; +retry: error = xfs_trans_reserve(tp, resp, blocks, rtextents); - if (error == -ENOSPC) { + if (error == -ENOSPC && !retried) { /* * We weren't able to reserve enough space for the transaction. * Flush the other speculative space allocations to free space. * Do not perform a synchronous scan because callers can hold * other locks. */ + retried = true; + if (!(flags & XFS_TRANS_NO_WRITECOUNT)) + sb_end_intwrite(mp->m_super); error = xfs_blockgc_free_space(mp, NULL); - if (!error) - error = xfs_trans_reserve(tp, resp, blocks, rtextents); - } - if (error) { + if (error) { + kmem_cache_free(xfs_trans_zone, tp); + return error; + } + if (!(flags & XFS_TRANS_NO_WRITECOUNT)) + sb_start_intwrite(mp->m_super); + goto retry; + } else if (error) { xfs_trans_cancel(tp); return error; }-- 2.26.2