diff options
Diffstat (limited to 'fs/xfs/xfs_aops.c')
| -rw-r--r-- | fs/xfs/xfs_aops.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 2705f91bdd0d..9d6a67c7d227 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -136,7 +136,20 @@ done: memalloc_nofs_restore(nofs_flag); } -/* Finish all pending io completions. */ +/* + * Finish all pending IO completions that require transactional modifications. + * + * We try to merge physical and logically contiguous ioends before completion to + * minimise the number of transactions we need to perform during IO completion. + * Both unwritten extent conversion and COW remapping need to iterate and modify + * one physical extent at a time, so we gain nothing by merging physically + * discontiguous extents here. + * + * The ioend chain length that we can be processing here is largely unbound in + * length and we may have to perform significant amounts of work on each ioend + * to complete it. Hence we have to be careful about holding the CPU for too + * long in this loop. + */ void xfs_end_io( struct work_struct *work) @@ -157,6 +170,7 @@ xfs_end_io( list_del_init(&ioend->io_list); iomap_ioend_try_merge(ioend, &tmp); xfs_end_ioend(ioend); + cond_resched(); } } |