fs: dcache scale dentry refcount
Make d_count non-atomic and protect it with d_lock. This allows us to ensure a
0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when
we start protecting many other dentry members with d_lock.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index a796c94..413b564 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -198,7 +198,7 @@
else
ino_count++;
- if (atomic_read(&p->d_count) > ino_count) {
+ if (p->d_count > ino_count) {
top_ino->last_used = jiffies;
dput(p);
return 1;
@@ -347,7 +347,7 @@
/* Path walk currently on this dentry? */
ino_count = atomic_read(&ino->count) + 2;
- if (atomic_read(&dentry->d_count) > ino_count)
+ if (dentry->d_count > ino_count)
goto next;
/* Can we umount this guy */
@@ -369,7 +369,7 @@
if (!exp_leaves) {
/* Path walk currently on this dentry? */
ino_count = atomic_read(&ino->count) + 1;
- if (atomic_read(&dentry->d_count) > ino_count)
+ if (dentry->d_count > ino_count)
goto next;
if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
@@ -383,7 +383,7 @@
} else {
/* Path walk currently on this dentry? */
ino_count = atomic_read(&ino->count) + 1;
- if (atomic_read(&dentry->d_count) > ino_count)
+ if (dentry->d_count > ino_count)
goto next;
expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index d34896c..7922509 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -436,7 +436,7 @@
spin_lock(&active->d_lock);
/* Already gone? */
- if (atomic_read(&active->d_count) == 0)
+ if (active->d_count == 0)
goto next;
qstr = &active->d_name;
@@ -452,7 +452,7 @@
goto next;
if (d_unhashed(active)) {
- dget(active);
+ dget_dlock(active);
spin_unlock(&active->d_lock);
spin_unlock(&sbi->lookup_lock);
spin_unlock(&dcache_lock);
@@ -507,7 +507,7 @@
goto next;
if (d_unhashed(expiring)) {
- dget(expiring);
+ dget_dlock(expiring);
spin_unlock(&expiring->d_lock);
spin_unlock(&sbi->lookup_lock);
spin_unlock(&dcache_lock);