e2fsck: optimize pass1 for CPU time

Optimize e2fsck pass 1 by marking entire extents as being in use at a
time, instead of block by block.  This optimization only works for
non-bigalloc file systems for now (it's tricky to handle bigalloc file
systems since this code is also responsible for dealing with blocks
that are not correctly aligned within a cluster).  When the
optimization works, the CPU savings can be significant: ove a full CPU
minute for a mostly full 4T disk.

Addresses-Google-Bug: #7534813

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>

diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 78fbe8d..cc00e0f 100644 (file)
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -1432,6 +1432,16 @@ static _INLINE_ void mark_block_used(e2fsck_t ctx, blk64_t block)
        }
 }
 
+static _INLINE_ void mark_blocks_used(e2fsck_t ctx, blk64_t block,
+                                     unsigned int num)
+{
+       if (ext2fs_test_block_bitmap_range2(ctx->block_found_map, block, num))
+               ext2fs_mark_block_bitmap_range2(ctx->block_found_map, block, num);
+       else
+               while (num--)
+                       mark_block_used(ctx, block++);
+}
+
 /*
  * Adjust the extended attribute block's reference counts at the end
  * of pass 1, either by subtracting out references for EA blocks that
@@ -1867,11 +1877,15 @@ static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx,
                                goto failed_add_dir_block;
                        }
                }
+               if (!ctx->fs->cluster_ratio_bits) {
+                       mark_blocks_used(ctx, extent.e_pblk, extent.e_len);
+                       pb->num_blocks += extent.e_len;
+               }
                for (blk = extent.e_pblk, blockcnt = extent.e_lblk, i = 0;
                     i < extent.e_len;
                     blk++, blockcnt++, i++) {
-                       if (!(ctx->fs->cluster_ratio_bits &&
-                             pb->previous_block &&
+                       if (ctx->fs->cluster_ratio_bits &&
+                           !(pb->previous_block &&
                              (EXT2FS_B2C(ctx->fs, blk) ==
                               EXT2FS_B2C(ctx->fs, pb->previous_block)) &&
                              (blk & EXT2FS_CLUSTER_MASK(ctx->fs)) ==