Rewrite lbatview_elem_realloc

* Only touch the data we need to touch.
 * Handle failure gracefully by reverting to old data.
 * Adjust libcbd check_one_lblk to ignore unused allocs.

dm-compress/lbatview.c

@@ -315,56 +315,64 @@ int
 lbatview_elem_realloc(struct lbatview* lv, u64 lblk, u32 len)
 {
     int ret = 0;
-    u32 req_nalloc;
+    int err;
     u32 elem_off;
+    u32 elem_len;
+    u32 req_nalloc;
+    u32 cur_nalloc;
+    u32 old_nalloc;
     u32 off;
-    u32 n;
     u64 pblk;
     u32 elem_lelen;
     u64 elem_lepblk;
 
-    if (len == CBD_UNCOMPRESSED) {
-        req_nalloc = lblk_per_pblk(lv->params);
-    }
-    else {
-        req_nalloc = DIV_ROUND_UP(len, PBLK_SIZE);
-    }
     mutex_lock(&lv->lock);
     elem_off = lbatview_elem_off(lv, lblk);
-    elem_lelen = __cpu_to_le32(len);
+    req_nalloc = (len == CBD_UNCOMPRESSED) ?
-    lbatview_wmem(lv, elem_off, lba_elem_len_bytes(lv->params), &elem_lelen);
+                     lblk_per_pblk(lv->params) :
-    off = elem_off + lba_elem_len_bytes(lv->params);
+                     DIV_ROUND_UP(len, PBLK_SIZE);
-    for (n = 0; n < lblk_per_pblk(lv->params); ++n, off += lba_elem_pblk_bytes(lv->params)) {
+    elem_lelen = 0;
+    lbatview_rmem(lv, elem_off, lba_elem_len_bytes(lv->params), &elem_lelen);
+    elem_len = __le32_to_cpu(elem_lelen);
+    cur_nalloc = (elem_len == CBD_UNCOMPRESSED) ?
+                     lblk_per_pblk(lv->params) :
+                     DIV_ROUND_UP(elem_len, PBLK_SIZE);
+    old_nalloc = cur_nalloc;
+
+    while (cur_nalloc < req_nalloc) {
+        off = elem_off + lba_elem_len_bytes(lv->params) +
+              cur_nalloc * lba_elem_pblk_bytes(lv->params);
+        pblk = lbatview_alloc_pblk(lv);
+        if (pblk == PBLK_NONE) {
+	    printk(KERN_ERR "%s: lbatview_alloc_pblk failed\n", __func__);
+	    ret = -ENOSPC;
+	    req_nalloc = old_nalloc;
+            goto do_free;
+        }
+        elem_lepblk = __cpu_to_le64(pblk);
+        lbatview_wmem(lv, off, lba_elem_pblk_bytes(lv->params), &elem_lepblk);
+        ++cur_nalloc;
+    }
+do_free:
+    while (cur_nalloc > req_nalloc) {
+        --cur_nalloc;
+        off = elem_off + lba_elem_len_bytes(lv->params) +
+              cur_nalloc * lba_elem_pblk_bytes(lv->params);
         elem_lepblk = 0;
         lbatview_rmem(lv, off, lba_elem_pblk_bytes(lv->params), &elem_lepblk);
         pblk = __le64_to_cpu(elem_lepblk);
-        if (pblk == 0) {
+        err = lbatview_free_pblk(lv, pblk);
-            if (n >= req_nalloc) {
+        if (err) {
-                break;
+            printk(KERN_ERR "%s: lbatview_free_pblk failed\n", __func__);
-            }
+            ret = err;
-            pblk = lbatview_alloc_pblk(lv);
-            if (pblk == PBLK_NONE) {
-                printk(KERN_ERR "%s: lbatview_alloc_pblk failed\n", __func__);
-                ret = -ENOSPC;
-                goto out; /* XXX: undo */
-            }
-            elem_lepblk = __cpu_to_le64(pblk);
-            lbatview_wmem(lv, off, lba_elem_pblk_bytes(lv->params), &elem_lepblk);
-        }
-        else {
-            if (n >= req_nalloc) {
-                elem_lepblk = 0;
-                lbatview_wmem(lv, off, lba_elem_pblk_bytes(lv->params), &elem_lepblk);
-                ret = lbatview_free_pblk(lv, pblk);
-                if (ret) {
-                    printk(KERN_ERR "%s: lbatview_free_pblk failed\n", __func__);
-                    goto out; /* XXX: undo */
-                }
-            }
         }
     }
 
-out:
+    if (!ret) {
+        elem_lelen = __cpu_to_le32(len);
+        lbatview_wmem(lv, elem_off, lba_elem_len_bytes(lv->params), &elem_lelen);
+    }
+
     mutex_unlock(&lv->lock);
     return ret;
 }

libcbd/check.c

@@ -65,7 +65,7 @@ check_one_lblk(const struct cbd_params* params,
 {
     struct lba* lba;
     u8* lba_buf;
-    u32 c_len;
+    u32 n_alloc;
     u32 n;
     u64 pblk;
 
@@ -87,45 +87,40 @@ check_one_lblk(const struct cbd_params* params,
         printf("    :E: Length out of bounds\n");
         return;
     }
-    c_len = (lba->len == CBD_UNCOMPRESSED) ? PBLK_SIZE * lblk_per_pblk(params) : lba->len;
+    n_alloc = (lba->len == CBD_UNCOMPRESSED) ?
-    for (n = 0; n < lblk_per_pblk(params); ++n) {
+                  lblk_per_pblk(params) :
+                  DIV_ROUND_UP(lba->len, PBLK_SIZE);
+    for (n = 0; n < n_alloc; ++n) {
+        u32 pblk_zone;
+        u32 rel_pblk;
         pblk = lba->pblk[n];
-        if (c_len > PBLK_SIZE * n) {
+        if (pblk < CBD_HEADER_BLOCKS) {
-            u32 pblk_zone;
+            printf("    [%u] :E: Alloc in header: %lu\n", n, pblk);
-            u32 rel_pblk;
+            continue;
-            if (pblk < CBD_HEADER_BLOCKS) {
-                printf("    [%u] :E: Alloc in header: %lu\n", n, pblk);
-                continue;
-            }
-            pblk_zone = (pblk - CBD_HEADER_BLOCKS) / zone_len(params);
-            if (pblk_zone >= params->nr_zones) {
-                printf("    [%u] :E: Alloc beyond end: %lu\n", n, pblk);
-                continue;
-            }
-            if (pblk < zone_data_off(params, pblk_zone)) {
-                printf("    [%u] :E: Alloc in metadata: %lu\n", n, pblk);
-                continue;
-            }
-            rel_pblk = pblk - zone_data_off(params, pblk_zone);
-            /* XXX: Cannot happen? */
-            if (rel_pblk >= pbat_len(params) * PBLK_SIZE_BITS) {
-                printf("    [%u] :E: Alloc out of zone: %lu\n", n, pblk);
-                continue;
-            }
-            printf("    [%u] pblk=%lu pblk_zone=%u rel_pblk=%u\n", n,
-                    (unsigned long)pblk, pblk_zone, rel_pblk);
-            if (pblk_used[pblk_zone][rel_pblk/8] & (1 << (rel_pblk % 8))) {
-                printf("    [%u] :E: Duplicate allocation for zone %u block %u\n",
-                        n, pblk_zone, rel_pblk);
-                continue;
-            }
-            pblk_used[pblk_zone][rel_pblk/8] |= (1 << (rel_pblk % 8));
         }
-        else {
+        pblk_zone = (pblk - CBD_HEADER_BLOCKS) / zone_len(params);
-            if (pblk) {
+        if (pblk_zone >= params->nr_zones) {
-                printf("    [%u] :E: Unexpected pblk alloc: %lu\n", n, pblk);
+            printf("    [%u] :E: Alloc beyond end: %lu\n", n, pblk);
-            }
+            continue;
         }
+        if (pblk < zone_data_off(params, pblk_zone)) {
+            printf("    [%u] :E: Alloc in metadata: %lu\n", n, pblk);
+            continue;
+        }
+        rel_pblk = pblk - zone_data_off(params, pblk_zone);
+        /* XXX: Cannot happen? */
+        if (rel_pblk >= pbat_len(params) * PBLK_SIZE_BITS) {
+            printf("    [%u] :E: Alloc out of zone: %lu\n", n, pblk);
+            continue;
+        }
+        printf("    [%u] pblk=%lu pblk_zone=%u rel_pblk=%u\n", n,
+                (unsigned long)pblk, pblk_zone, rel_pblk);
+        if (pblk_used[pblk_zone][rel_pblk/8] & (1 << (rel_pblk % 8))) {
+            printf("    [%u] :E: Duplicate allocation for zone %u block %u\n",
+                    n, pblk_zone, rel_pblk);
+            continue;
+        }
+        pblk_used[pblk_zone][rel_pblk/8] |= (1 << (rel_pblk % 8));
     }
 
     free(lba);