verity: change maybe_read_entries to maybe_read_entry
Since root is guaranteed to be a single block we no longer need to
read multiple entries in maybe_read_entries.
BUG=9752
TEST=Ran dm-verity.git unit tests. Ran platform_DMVerityCorruption on H/W.
kernel-next.git Review URL: http://codereview.chromium.org/6821076
TBRing. Already LGTMed and committed to kernel-next.git
Change-Id: I23e19d13e7f3b079a5fe739be7fdd9f2df760335
R=wad@chromium.org,taysom@chromium.org
Review URL: http://codereview.chromium.org/6880133
diff --git a/dm-bht.c b/dm-bht.c
index 72af2a7..1b53ffc 100644
--- a/dm-bht.c
+++ b/dm-bht.c
@@ -305,6 +305,9 @@
if (status)
goto bad_entries_alloc;
+ /* We compute depth such that there is only be 1 block at level 0. */
+ BUG_ON(bht->levels[0].count != 1);
+
return 0;
bad_entries_alloc:
@@ -461,100 +464,68 @@
}
EXPORT_SYMBOL(dm_bht_write_completed);
-
-/* dm_bht_maybe_read_entries
- * Attempts to atomically acquire each entry, allocated any needed
- * memory, and issues I/O callbacks to load the hashes from disk.
- * Returns 0 if all entries are loaded and verified. On error, the
- * return value is negative. When positive, it is the state values
- * ORd.
+/* dm_bht_maybe_read_entry
+ * Attempts to atomically acquire an entry, allocate any needed
+ * memory, and issues the I/O callback to load the hash from disk.
+ * Return value is negative on error. When positive, it is the state
+ * value.
*/
-static int dm_bht_maybe_read_entries(struct dm_bht *bht, void *ctx,
- unsigned int depth, unsigned int index,
- unsigned int count, bool until_exist)
+static int dm_bht_maybe_read_entry(struct dm_bht *bht, void *ctx,
+ unsigned int depth, unsigned int index)
{
- struct dm_bht_level *level;
- struct dm_bht_entry *entry, *last_entry;
- sector_t current_sector;
- int state = 0;
- int status = 0;
- struct page *node_page = NULL;
+ struct dm_bht_level *level = &bht->levels[depth];
+ struct dm_bht_entry *entry = &level->entries[index];
+ sector_t current_sector = level->sector + to_sector(index * PAGE_SIZE);
+ struct page *node_page;
+ int state;
+
BUG_ON(depth >= bht->depth);
- level = &bht->levels[depth];
- if (count > level->count - index) {
- DMERR("dm_bht_maybe_read_entries(d=%u,ei=%u,count=%u): "
- "index+count exceeds available entries %u",
- depth, index, count, level->count);
- return -EINVAL;
- }
/* XXX: hardcoding PAGE_SIZE means that a perfectly valid image
* on one system may not work on a different kernel.
* TODO(wad) abstract PAGE_SIZE with a bht->entry_size or
* at least a define and ensure bht->entry_size is
* sector aligned at least.
*/
- current_sector = level->sector + to_sector(index * PAGE_SIZE);
- for (entry = &level->entries[index], last_entry = entry + count;
- entry < last_entry;
- ++entry, current_sector += to_sector(PAGE_SIZE)) {
- /* If the entry's state is UNALLOCATED, then we'll claim it
- * for allocation and loading.
- */
- state = atomic_cmpxchg(&entry->state,
- DM_BHT_ENTRY_UNALLOCATED,
- DM_BHT_ENTRY_PENDING);
- DMDEBUG("dm_bht_maybe_read_entries(d=%u,ei=%u,count=%u): "
- "ei=%lu, state=%d",
- depth, index, count,
- (unsigned long)(entry - level->entries), state);
- if (state <= DM_BHT_ENTRY_ERROR) {
- DMCRIT("entry %u is in an error state", index);
- return state;
- }
- /* Currently, the verified state is unused. */
- if (state == DM_BHT_ENTRY_VERIFIED) {
- if (until_exist)
- return 0;
- /* Makes 0 == verified. Is that ideal? */
- continue;
- }
+ /* If the entry's state is UNALLOCATED, then we'll claim it
+ * for allocation and loading.
+ */
+ state = atomic_cmpxchg(&entry->state,
+ DM_BHT_ENTRY_UNALLOCATED,
+ DM_BHT_ENTRY_PENDING);
+ DMDEBUG("dm_bht_maybe_read_entry(d=%u,ei=%u): ei=%lu, state=%d",
+ depth, index, (unsigned long)(entry - level->entries), state);
- if (state != DM_BHT_ENTRY_UNALLOCATED) {
- /* PENDING, READY, ... */
- if (until_exist)
- return state;
- status |= state;
- continue;
- }
- /* Current entry is claimed for allocation and loading */
- node_page = (struct page *) mempool_alloc(bht->entry_pool,
- GFP_NOIO);
- if (!node_page) {
- DMCRIT("failed to allocate memory for "
- "entry->nodes from pool");
- return -ENOMEM;
- }
- /* dm-bht guarantees page-aligned memory for callbacks. */
- entry->nodes = page_address(node_page);
- /* Let the caller know that not all the data is yet available */
- status |= DM_BHT_ENTRY_REQUESTED;
- /* Issue the read callback */
- /* TODO(wad) error check callback here too */
- DMDEBUG("dm_bht_maybe_read_entries(d=%u,ei=%u,count=%u): "
- "reading %lu",
- depth, index, count,
- (unsigned long)(entry - level->entries));
- bht->read_cb(ctx, /* external context */
- current_sector, /* starting sector */
- entry->nodes, /* destination */
- to_sector(PAGE_SIZE),
- entry); /* io context */
+ if (state != DM_BHT_ENTRY_UNALLOCATED)
+ goto out;
- }
- /* Should only be 0 if all entries were verified and not just ready */
- return status;
+ state = DM_BHT_ENTRY_REQUESTED;
+
+ /* Current entry is claimed for allocation and loading */
+ node_page = (struct page *) mempool_alloc(bht->entry_pool, GFP_NOIO);
+ if (!node_page)
+ goto nomem;
+ /* dm-bht guarantees page-aligned memory for callbacks. */
+ entry->nodes = page_address(node_page);
+
+ /* TODO(wad) error check callback here too */
+ DMDEBUG("dm_bht_maybe_read_entry(d=%u,ei=%u): reading %lu",
+ depth, index, (unsigned long)(entry - level->entries));
+ bht->read_cb(ctx, current_sector, entry->nodes,
+ to_sector(PAGE_SIZE), entry);
+
+out:
+ if (state <= DM_BHT_ENTRY_ERROR)
+ DMCRIT("entry %u is in an error state", index);
+
+ return state;
+
+nomem:
+ DMCRIT("failed to allocate memory for entry->nodes from pool");
+ return -ENOMEM;
+
+
}
static int dm_bht_compare_hash(struct dm_bht *bht, u8 *known, u8 *computed)
@@ -824,15 +795,15 @@
struct dm_bht_entry *child = child_level->entries;
unsigned int i, j;
- r = dm_bht_maybe_read_entries(bht, read_cb_ctx, depth,
- 0, level->count, true);
- if (r < 0) {
- DMCRIT("an error occurred while reading entry");
- goto out;
- }
-
for (i = 0; i < level->count; i++, entry++) {
unsigned int count = bht->node_count;
+
+ r = dm_bht_maybe_read_entry(bht, read_cb_ctx, depth, i);
+ if (r < 0) {
+ DMCRIT("an error occurred while reading entry");
+ goto out;
+ }
+
if (i == (level->count - 1))
count = child_level->count % bht->node_count;
if (count == 0)
@@ -968,9 +939,7 @@
if (root_state != DM_BHT_ENTRY_VERIFIED) {
DMDEBUG("root data is not yet loaded");
/* If positive, it means some are pending. */
- populated = dm_bht_maybe_read_entries(bht, read_cb_ctx, 0, 0,
- bht->levels[0].count,
- true);
+ populated = dm_bht_maybe_read_entry(bht, read_cb_ctx, 0, 0);
if (populated < 0) {
DMCRIT("an error occurred while reading level[0]");
/* TODO(wad) define std error codes */
@@ -988,9 +957,8 @@
/* Except for the root node case, we should only ever need
* to load one entry along the path.
*/
- read_status = dm_bht_maybe_read_entries(bht, read_cb_ctx,
- depth, entry_index,
- 1, false);
+ read_status = dm_bht_maybe_read_entry(bht, read_cb_ctx,
+ depth, entry_index);
if (unlikely(read_status < 0)) {
DMCRIT("failure occurred reading entry %u depth %u",
entry_index, depth);
