From: NeilBrown <neilb@suse.de>
Date: Wed, 15 Sep 2010 05:19:50 +0000 (+1000)
Subject: lafs_refile:  group all functionality that requires refcnt==0
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=89ccd1af4915d9562752c95c67809ee4e118b8a1;p=LaFS.git

lafs_refile:  group all functionality that requires refcnt==0

There are multiple silly (racy) tests on refcnt==dec.  Combine all
these tests into a single 'if' which is run only when the refcnt
reaches zero.

This patch just changes the code without fixing the indentation.  That
makes it easier to review.

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/index.c b/index.c
index ebef167..a3e0afd 100644
--- a/index.c
+++ b/index.c
@@ -890,6 +890,7 @@ void lafs_refile(struct block *b, int dec)
 		int free_me = 0;
 		struct inode *checkpin = NULL;
 		struct inode *myi = NULL;
+		struct datablock *db;
 
 		set_lru(b);
 
@@ -923,12 +924,13 @@ void lafs_refile(struct block *b, int dec)
 			lafs_checkpoint_unlock(fs);
 		}
 
-		spin_lock(&lafs_hash_lock);
 
+
+		if (dec && _putref_norefile(b)) {
+		spin_lock(&lafs_hash_lock);
 		/* PinPending disappears with the last non-lru reference,
 		 * (or possibly at other times).
 		 */
-		if (atomic_read(&b->refcnt) == dec)
 			clear_bit(B_PinPending, &b->flags);
 
 		ph = !!test_bit(B_Phase1, &b->flags);
@@ -938,7 +940,6 @@ void lafs_refile(struct block *b, int dec)
 		    !test_bit(B_PinPending, &b->flags) &&
 		    !test_bit(B_Dirty, &b->flags) &&
 		    !test_bit(B_Realloc, &b->flags) &&
-		    atomic_read(&b->refcnt) == dec &&
 		    (!test_bit(B_Index, &b->flags) ||
 		     (iblk(b)->uninc_table.pending_cnt == 0 &&
 		      iblk(b)->uninc == NULL &&
@@ -975,7 +976,6 @@ void lafs_refile(struct block *b, int dec)
 		}
 
 		/* check the ->parent link */
-		if (atomic_read(&b->refcnt) == dec) {
 			if (b->parent &&
 			    !(b->flags & (
 				      (1<<B_Pinned) |
@@ -1063,17 +1063,13 @@ void lafs_refile(struct block *b, int dec)
 				}
 				freelist.freecnt++;
 			}
-		}
-
-		if (dec) {
-			if (_putref_norefile(b)) {
 				/* last reference to a dblock with no page
 				 * requires special handling
 				 * The first block on a page must be freed,
 				 * the other blocks hold a reference on that
 				 * first block which must be dropped.
 				 */
-				struct datablock *db = dblk(b);
+				db = dblk(b);
 				if (!test_bit(B_Index, &b->flags) &&
 				    !PagePrivate(db->page)) {
 					int bits = (PAGE_SHIFT -
@@ -1106,12 +1102,9 @@ void lafs_refile(struct block *b, int dec)
 					spin_unlock(&b->inode->i_data
 						    .private_lock);
 				}
-			}
-		}
 
 		/* Free a delayed-release inode */
-		if (atomic_read(&b->refcnt) == 0 &&
-		    !test_bit(B_Index, &b->flags) &&
+		if (!test_bit(B_Index, &b->flags) &&
 		    (myi = rcu_my_inode(dblk(b))) != NULL &&
 		    (!PagePrivate(dblk(b)->page) ||
 		     test_bit(I_Destroyed, &LAFSI(myi)->iflags))) {
@@ -1123,6 +1116,7 @@ void lafs_refile(struct block *b, int dec)
 				lafs_destroy_inode(myi);
 		} else
 			spin_unlock(&lafs_hash_lock);
+		}
 		rcu_iput(myi);
 
 		if (physref) {