The list_lock was moved outside the for loop by commit
e8dfc30582995ae12454cda517b17d6294175b07 ("writeback: elevate queue_io()
into wb_writeback())", however, the commit log says "No behavior change", so
it sounds safe to have the list_lock acquired inside the for loop as it did
before.
Leave tracepoints outside the critical area since tracepoints already have
preempt disabled.Signed-off-by: Yang Shi <[email protected]> --- Tested with ltp on 8 cores Cortex-A57 machine. fs/fs-writeback.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 1f76d89..9b7b5f6 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1623,7 +1623,6 @@ static long wb_writeback(struct bdi_writeback *wb, work->older_than_this = &oldest_jif; blk_start_plug(&plug); - spin_lock(&wb->list_lock); for (;;) { /* * Stop writeback when nr_pages has been consumed @@ -1661,15 +1660,19 @@ static long wb_writeback(struct bdi_writeback *wb, oldest_jif = jiffies; trace_writeback_start(wb, work); + + spin_lock(&wb->list_lock); if (list_empty(&wb->b_io)) queue_io(wb, work); if (work->sb) progress = writeback_sb_inodes(work->sb, wb, work); else progress = __writeback_inodes_wb(wb, work); - trace_writeback_written(wb, work); wb_update_bandwidth(wb, wb_start); + spin_unlock(&wb->list_lock); + + trace_writeback_written(wb, work); /* * Did we write something? Try for more @@ -1693,15 +1696,14 @@ static long wb_writeback(struct bdi_writeback *wb, */ if (!list_empty(&wb->b_more_io)) { trace_writeback_wait(wb, work); + spin_lock(&wb->list_lock); inode = wb_inode(wb->b_more_io.prev); - spin_lock(&inode->i_lock); spin_unlock(&wb->list_lock); + spin_lock(&inode->i_lock); /* This function drops i_lock... */ inode_sleep_on_writeback(inode); - spin_lock(&wb->list_lock); } } - spin_unlock(&wb->list_lock); blk_finish_plug(&plug); return nr_pages - work->nr_pages; -- 2.0.2
