Added debug statement for block allocation scan

This may be useful for determining when allocation passes occur,
especially as performance and latency becomes a growing concern.

Makefile

@@ -55,7 +55,6 @@ test: \
 	test_attrs \
 	test_move \
 	test_orphan \
-	test_relocations \
 	test_corrupt
 	@rm test.c
 test_%: tests/test_%.sh

lfs.c

@@ -466,9 +466,15 @@ static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
             }
         }
 
+        // no free blocks in lookahead buffer, need to scan tree
+        LFS_DEBUG("Scanning for free blocks %"PRIx32"-%"PRIx32,
+                lfs->free.i + lfs->free.off,
+                (lfs->free.i + lfs->free.off + 8*lfs->cfg->lookahead_size)
+                    % lfs->cfg->block_count);
+
         // check if we have looked at all blocks since last ack
         if (lfs->free.ack == 0) {
-            LFS_ERROR("No more free space %"PRIu32,
+            LFS_ERROR("No more free space %"PRIx32,
                     lfs->free.i + lfs->free.off);
             return LFS_ERR_NOSPC;
         }
@@ -1503,13 +1509,9 @@ static int lfs_dir_compact(lfs_t *lfs,
                 }
             }
 #ifdef LFS_MIGRATE
-        } else if (lfs->lfs1) {
-            // do not proactively relocate blocks during migrations, this
-            // can cause a number of failure states such: clobbering the
-            // v1 superblock if we relocate root, and invalidating directory
-            // pointers if we relocate the head of a directory. On top of
-            // this, relocations increase the overall complexity of
-            // lfs_migration, which is already a delicate operation.
+        } else if (lfs_pair_cmp(dir->pair, lfs->root) == 0 && lfs->lfs1) {
+            // we can't relocate our root during migrations, as this would
+            // cause the superblock to get updated, which would clobber v1
 #endif
         } else {
             // we're writing too much, time to relocate
@@ -2107,6 +2109,8 @@ int lfs_dir_rewind(lfs_t *lfs, lfs_dir_t *dir) {
         return err;
     }
 
+    dir->m.pair[0] = dir->head[0];
+    dir->m.pair[1] = dir->head[1];
     dir->id = 0;
     dir->pos = 0;
     LFS_TRACE("lfs_dir_rewind -> %d", 0);
@@ -3889,12 +3893,6 @@ static int lfs_fs_relocate(lfs_t *lfs,
             d->m.pair[0] = newpair[0];
             d->m.pair[1] = newpair[1];
         }
-
-        if (d->type == LFS_TYPE_DIR &&
-                lfs_pair_cmp(oldpair, ((lfs_dir_t*)d)->head) == 0) {
-            ((lfs_dir_t*)d)->head[0] = newpair[0];
-            ((lfs_dir_t*)d)->head[1] = newpair[1];
-        }
     }
 
     // find parent

tests/test_relocations.sh

@@ -1,88 +0,0 @@
-#!/bin/bash
-set -eu
-export TEST_FILE=$0
-trap 'export TEST_LINE=$LINENO' DEBUG
-
-ITERATIONS=20
-COUNT=10
-
-echo "=== Relocation tests ==="
-rm -rf blocks
-scripts/test.py << TEST
-    lfs_format(&lfs, &cfg) => 0;
-    // fill up filesystem so only ~16 blocks are left
-    lfs_mount(&lfs, &cfg) => 0;
-    lfs_file_open(&lfs, &file, "padding", LFS_O_CREAT | LFS_O_WRONLY) => 0;
-    memset(buffer, 0, 512);
-    while (LFS_BLOCK_COUNT - lfs_fs_size(&lfs) > 16) {
-        lfs_file_write(&lfs, &file, buffer, 512) => 512;
-    }
-    lfs_file_close(&lfs, &file) => 0;
-    // make a child dir to use in bounded space
-    lfs_mkdir(&lfs, "child") => 0;
-    lfs_unmount(&lfs) => 0;
-TEST
-
-echo "--- Outdated head test ---"
-scripts/test.py << TEST
-    lfs_mount(&lfs, &cfg) => 0;
-    for (int j = 0; j < $ITERATIONS; j++) {
-        for (int i = 0; i < $COUNT; i++) {
-            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
-            lfs_file_open(&lfs, &file, path, LFS_O_CREAT | LFS_O_WRONLY) => 0;
-            lfs_file_close(&lfs, &file) => 0;
-        }
-
-        lfs_dir_open(&lfs, &dir, "child") => 0;
-        lfs_dir_read(&lfs, &dir, &info) => 1;
-        lfs_dir_read(&lfs, &dir, &info) => 1;
-        for (int i = 0; i < $COUNT; i++) {
-            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
-            lfs_dir_read(&lfs, &dir, &info) => 1;
-            strcmp(info.name, path) => 0;
-            info.size => 0;
-
-            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
-            lfs_file_open(&lfs, &file, path, LFS_O_WRONLY) => 0;
-            lfs_file_write(&lfs, &file, "hi", 2) => 2;
-            lfs_file_close(&lfs, &file) => 0;
-        }
-        lfs_dir_read(&lfs, &dir, &info) => 0;
-
-        lfs_dir_rewind(&lfs, &dir) => 0;
-        lfs_dir_read(&lfs, &dir, &info) => 1;
-        lfs_dir_read(&lfs, &dir, &info) => 1;
-        for (int i = 0; i < $COUNT; i++) {
-            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
-            lfs_dir_read(&lfs, &dir, &info) => 1;
-            strcmp(info.name, path) => 0;
-            info.size => 2;
-
-            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
-            lfs_file_open(&lfs, &file, path, LFS_O_WRONLY) => 0;
-            lfs_file_write(&lfs, &file, "hi", 2) => 2;
-            lfs_file_close(&lfs, &file) => 0;
-        }
-        lfs_dir_read(&lfs, &dir, &info) => 0;
-
-        lfs_dir_rewind(&lfs, &dir) => 0;
-        lfs_dir_read(&lfs, &dir, &info) => 1;
-        lfs_dir_read(&lfs, &dir, &info) => 1;
-        for (int i = 0; i < $COUNT; i++) {
-            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
-            lfs_dir_read(&lfs, &dir, &info) => 1;
-            strcmp(info.name, path) => 0;
-            info.size => 2;
-        }
-        lfs_dir_read(&lfs, &dir, &info) => 0;
-        lfs_dir_close(&lfs, &dir) => 0;
-
-        for (int i = 0; i < $COUNT; i++) {
-            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
-            lfs_remove(&lfs, path) => 0;
-        }
-    }
-    lfs_unmount(&lfs) => 0;
-TEST
-
-scripts/results.py