cfs: force whole compaction under lock on huge files

Author: Sokolov Yura

src/backend/storage/file/cfs.c

@@ -992,8 +992,11 @@ static bool cfs_gc_file(char* map_path, GC_CALL_KIND background)
 		cfs_gc_lock(lock);
 
 		/* Reread variables after locking file */
+		physSize = pg_atomic_read_u32(&map->hdr.physSize);
 		virtSize = pg_atomic_read_u32(&map->hdr.virtSize);
 		n_pages = virtSize / BLCKSZ;
+		if (physSize >= CFS_RED_LINE)
+			goto forceWhole;
 		for (i = 0; i < n_pages; i++)
 		{
 			newMap->inodes[i] = map->inodes[i];
@@ -1073,7 +1076,7 @@ static bool cfs_gc_file(char* map_path, GC_CALL_KIND background)
 			memset(newMap->inodes, 0, sizeof(newMap->inodes));
 			elog(LOG, "CFS: retry %d whole gc file %s", second_pass_whole,
 					file_path);
-			if (second_pass_whole == 1 && physSize < CFS_IMPLICIT_GC_THRESHOLD)
+			if (second_pass_whole == 1 && physSize < CFS_RETRY_GC_THRESHOLD)
 			{
 				cfs_gc_unlock(lock);
 				/* sleep, cause there is possibly checkpoint is on a way */
@@ -1082,6 +1085,7 @@ static bool cfs_gc_file(char* map_path, GC_CALL_KIND background)
 				second_pass_bytes = 0;
 				goto retry;
 			}
+		forceWhole:
 			for (i = 0; i < n_pages; i++)
 			{
 				newMap->inodes[i] = map->inodes[i];

src/include/storage/cfs.h

@@ -53,6 +53,7 @@ typedef uint64 inode_t;
 #define CFS_INODE_CLEAN_FLAG  ((inode_t)1 << 63)
 
 #define CFS_IMPLICIT_GC_THRESHOLD 0x80000000U /* 2Gb */
+#define CFS_RETRY_GC_THRESHOLD    0x60000000U /* 1.5Gb */
 #define CFS_RED_LINE              0xC0000000U /* 3Gb */
 
 size_t cfs_compress(void* dst, size_t dst_size, void const* src, size_t src_size);