f2fs: move f2fs to use reader-unfair rwsems

f2fs rw_semaphores work better if writers can starve readers,
especially for the checkpoint thread, because writers are strictly
more important than reader threads. This prevents significant priority
inversion between low-priority readers that blocked while trying to
acquire the read lock and a second acquisition of the write lock that
might be blocking high priority work.

Signed-off-by: Tim Murray <timmurray@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 17 insertions, 17 deletions

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 982f0170639f..deeda95688f0 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -351,13 +351,13 @@ static int f2fs_write_meta_pages(struct address_space *mapping,
 		goto skip_write;
 
 	/* if locked failed, cp will flush dirty pages instead */
-	if (!down_write_trylock(&sbi->cp_global_sem))
+	if (!f2fs_down_write_trylock(&sbi->cp_global_sem))
 		goto skip_write;
 
 	trace_f2fs_writepages(mapping->host, wbc, META);
 	diff = nr_pages_to_write(sbi, META, wbc);
 	written = f2fs_sync_meta_pages(sbi, META, wbc->nr_to_write, FS_META_IO);
-	up_write(&sbi->cp_global_sem);
+	f2fs_up_write(&sbi->cp_global_sem);
 	wbc->nr_to_write = max((long)0, wbc->nr_to_write - written - diff);
 	return 0;
 
@@ -1159,7 +1159,7 @@ static bool __need_flush_quota(struct f2fs_sb_info *sbi)
 	if (!is_journalled_quota(sbi))
 		return false;
 
-	if (!down_write_trylock(&sbi->quota_sem))
+	if (!f2fs_down_write_trylock(&sbi->quota_sem))
 		return true;
 	if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) {
 		ret = false;
@@ -1171,7 +1171,7 @@ static bool __need_flush_quota(struct f2fs_sb_info *sbi)
 	} else if (get_pages(sbi, F2FS_DIRTY_QDATA)) {
 		ret = true;
 	}
-	up_write(&sbi->quota_sem);
+	f2fs_up_write(&sbi->quota_sem);
 	return ret;
 }
 
@@ -1228,10 +1228,10 @@ retry_flush_dents:
 	 * POR: we should ensure that there are no dirty node pages
 	 * until finishing nat/sit flush. inode->i_blocks can be updated.
 	 */
-	down_write(&sbi->node_change);
+	f2fs_down_write(&sbi->node_change);
 
 	if (get_pages(sbi, F2FS_DIRTY_IMETA)) {
-		up_write(&sbi->node_change);
+		f2fs_up_write(&sbi->node_change);
 		f2fs_unlock_all(sbi);
 		err = f2fs_sync_inode_meta(sbi);
 		if (err)
@@ -1241,15 +1241,15 @@ retry_flush_dents:
 	}
 
 retry_flush_nodes:
-	down_write(&sbi->node_write);
+	f2fs_down_write(&sbi->node_write);
 
 	if (get_pages(sbi, F2FS_DIRTY_NODES)) {
-		up_write(&sbi->node_write);
+		f2fs_up_write(&sbi->node_write);
 		atomic_inc(&sbi->wb_sync_req[NODE]);
 		err = f2fs_sync_node_pages(sbi, &wbc, false, FS_CP_NODE_IO);
 		atomic_dec(&sbi->wb_sync_req[NODE]);
 		if (err) {
-			up_write(&sbi->node_change);
+			f2fs_up_write(&sbi->node_change);
 			f2fs_unlock_all(sbi);
 			return err;
 		}
@@ -1262,13 +1262,13 @@ retry_flush_nodes:
 	 * dirty node blocks and some checkpoint values by block allocation.
 	 */
 	__prepare_cp_block(sbi);
-	up_write(&sbi->node_change);
+	f2fs_up_write(&sbi->node_change);
 	return err;
 }
 
 static void unblock_operations(struct f2fs_sb_info *sbi)
 {
-	up_write(&sbi->node_write);
+	f2fs_up_write(&sbi->node_write);
 	f2fs_unlock_all(sbi);
 }
 
@@ -1612,7 +1612,7 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 		f2fs_warn(sbi, "Start checkpoint disabled!");
 	}
 	if (cpc->reason != CP_RESIZE)
-		down_write(&sbi->cp_global_sem);
+		f2fs_down_write(&sbi->cp_global_sem);
 
 	if (!is_sbi_flag_set(sbi, SBI_IS_DIRTY) &&
 		((cpc->reason & CP_FASTBOOT) || (cpc->reason & CP_SYNC) ||
@@ -1693,7 +1693,7 @@ stop:
 	trace_f2fs_write_checkpoint(sbi->sb, cpc->reason, "finish checkpoint");
 out:
 	if (cpc->reason != CP_RESIZE)
-		up_write(&sbi->cp_global_sem);
+		f2fs_up_write(&sbi->cp_global_sem);
 	return err;
 }
 
@@ -1741,9 +1741,9 @@ static int __write_checkpoint_sync(struct f2fs_sb_info *sbi)
 	struct cp_control cpc = { .reason = CP_SYNC, };
 	int err;
 
-	down_write(&sbi->gc_lock);
+	f2fs_down_write(&sbi->gc_lock);
 	err = f2fs_write_checkpoint(sbi, &cpc);
-	up_write(&sbi->gc_lock);
+	f2fs_up_write(&sbi->gc_lock);
 
 	return err;
 }
@@ -1831,9 +1831,9 @@ int f2fs_issue_checkpoint(struct f2fs_sb_info *sbi)
 	if (!test_opt(sbi, MERGE_CHECKPOINT) || cpc.reason != CP_SYNC) {
 		int ret;
 
-		down_write(&sbi->gc_lock);
+		f2fs_down_write(&sbi->gc_lock);
 		ret = f2fs_write_checkpoint(sbi, &cpc);
-		up_write(&sbi->gc_lock);
+		f2fs_up_write(&sbi->gc_lock);
 
 		return ret;
 	}