Changes in / [e0e568ff:a7a85d16] in mainline

File:

• uspace/srv/fs/fat/fat_ops.c (modified) (4 diffs)

uspace/srv/fs/fat/fat_ops.c

@@ -369 +369 @@
         unsigned blocks;
         fat_dentry_t *d;
-        dev_handle_t dev_handle;
         block_t *b;
         int rc;
 
         fibril_mutex_lock(&parentp->idx->lock);
-        dev_handle = parentp->idx->dev_handle;
-        fibril_mutex_unlock(&parentp->idx->lock);
-
-        bs = block_bb_get(dev_handle);
+        bs = block_bb_get(parentp->idx->dev_handle);
         blocks = parentp->size / BPS(bs);
         for (i = 0; i < blocks; i++) {
                 rc = fat_block_get(&b, bs, parentp, i, BLOCK_FLAGS_NONE);
-                if (rc != EOK)
+                if (rc != EOK) {
+                        fibril_mutex_unlock(&parentp->idx->lock);
                         return rc;
+                }
                 for (j = 0; j < DPS(bs); j++) { 
                         d = ((fat_dentry_t *)b->data) + j;
@@ -392 +390 @@
                                 /* miss */
                                 rc = block_put(b);
+                                fibril_mutex_unlock(&parentp->idx->lock);
                                 *rfn = NULL;
                                 return rc;
@@ -402 +401 @@
                                 /* hit */
                                 fat_node_t *nodep;
-                                fat_idx_t *idx = fat_idx_get_by_pos(dev_handle,
-                                    parentp->firstc, i * DPS(bs) + j);
+                                /*
+                                 * Assume tree hierarchy for locking.  We
+                                 * already have the parent and now we are going
+                                 * to lock the child.  Never lock in the oposite
+                                 * order.
+                                 */
+                                fat_idx_t *idx = fat_idx_get_by_pos(
+                                    parentp->idx->dev_handle, parentp->firstc,
+                                    i * DPS(bs) + j);
+                                fibril_mutex_unlock(&parentp->idx->lock);
                                 if (!idx) {
                                         /*
@@ -426 +433 @@
                 }
                 rc = block_put(b);
-                if (rc != EOK)
+                if (rc != EOK) {
+                        fibril_mutex_unlock(&parentp->idx->lock);
                         return rc;
-        }
-
+                }
+        }
+
+        fibril_mutex_unlock(&parentp->idx->lock);
         *rfn = NULL;
         return EOK;