verity: short circuit once you hit a verified node
Since we set the VERIFIED bits top-down we can short circuit once
we hit a VERIFIED node.
BUG=9752
TEST=Ran tests in verity.git. Ran platform_DMVerityCorruption on H/W.
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
kernel.git Review URL: http://codereview.chromium.org/6670008
TBRing because code has already been LGTMed and committed to kernel.git.
Change-Id: Ib8fe833668a62bdc21946e2b274f970b0955cd8c
TBR=wad@chromium.org,taysom@chromium.org,ups@chromium.org
Review URL: http://codereview.chromium.org/6721017
diff --git a/dm-bht.c b/dm-bht.c
index 46b03c0..4c262a5 100644
--- a/dm-bht.c
+++ b/dm-bht.c
@@ -691,12 +691,13 @@
int state;
DMDEBUG("verify_path for b=%u on d=%d", block_index, depth);
+ /* TODO(msb,wad): would be nice to avoid two atomic reads */
state = atomic_read(&entry->state);
if (state == DM_BHT_ENTRY_VERIFIED) {
- DMDEBUG("verify_path node %u is verified in parent",
+ DMDEBUG("verify_path node %u is verified to root",
block_index);
- entry = dm_bht_get_entry(bht, --depth, block_index);
- continue;
+ depth++; /* avoid an extra cmpxchg */
+ break;
} else if (state <= DM_BHT_ENTRY_ERROR) {
DMCRIT("entry(d=%u,b=%u) is in an error state: %d",
depth, block_index, state);
@@ -726,12 +727,15 @@
goto mismatch;
}
+ entry = parent;
+ depth--;
+ }
+ /* Mark path to leaf as verified. */
+ for (; depth < bht->depth; depth++) {
+ entry = dm_bht_get_entry(bht, depth, block_index);
atomic_cmpxchg(&entry->state,
DM_BHT_ENTRY_READY,
DM_BHT_ENTRY_VERIFIED);
-
- entry = parent;
- depth--;
}
return 0;
