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-rw-r--r--fs/gfs2/glock.c93
1 files changed, 74 insertions, 19 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 49512696160..8abfefe4efd 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -53,8 +53,59 @@ typedef void (*glock_examiner) (struct gfs2_glock * gl);
static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
static int dump_glock(struct gfs2_glock *gl);
+#define GFS2_GL_HASH_SHIFT 13
+#define GFS2_GL_HASH_SIZE (1 << GFS2_GL_HASH_SHIFT)
+#define GFS2_GL_HASH_MASK (GFS2_GL_HASH_SIZE - 1)
+
static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];
-static rwlock_t gl_hash_locks[GFS2_GL_HASH_SIZE];
+
+/*
+ * Despite what you might think, the numbers below are not arbitrary :-)
+ * They are taken from the ipv4 routing hash code, which is well tested
+ * and thus should be nearly optimal. Later on we might tweek the numbers
+ * but for now this should be fine.
+ *
+ * The reason for putting the locks in a separate array from the list heads
+ * is that we can have fewer locks than list heads and save memory. We use
+ * the same hash function for both, but with a different hash mask.
+ */
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
+ defined(CONFIG_PROVE_LOCKING)
+
+#ifdef CONFIG_LOCKDEP
+# define GL_HASH_LOCK_SZ 256
+#else
+# if NR_CPUS >= 32
+# define GL_HASH_LOCK_SZ 4096
+# elif NR_CPUS >= 16
+# define GL_HASH_LOCK_SZ 2048
+# elif NR_CPUS >= 8
+# define GL_HASH_LOCK_SZ 1024
+# elif NR_CPUS >= 4
+# define GL_HASH_LOCK_SZ 512
+# else
+# define GL_HASH_LOCK_SZ 256
+# endif
+#endif
+
+/* We never want more locks than chains */
+#if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ
+# undef GL_HASH_LOCK_SZ
+# define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE
+#endif
+
+static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ];
+
+static inline rwlock_t *gl_lock_addr(unsigned int x)
+{
+ return &gl_hash_locks[(x) & (GL_HASH_LOCK_SZ-1)];
+}
+#else /* not SMP, so no spinlocks required */
+static inline rwlock_t *gl_lock_addr(x)
+{
+ return NULL;
+}
+#endif
/**
* relaxed_state_ok - is a requested lock compatible with the current lock mode?
@@ -161,16 +212,16 @@ int gfs2_glock_put(struct gfs2_glock *gl)
{
int rv = 0;
- write_lock(&gl_hash_locks[gl->gl_hash]);
+ write_lock(gl_lock_addr(gl->gl_hash));
if (kref_put(&gl->gl_ref, kill_glock)) {
list_del_init(&gl_hash_table[gl->gl_hash].hb_list);
- write_unlock(&gl_hash_locks[gl->gl_hash]);
+ write_unlock(gl_lock_addr(gl->gl_hash));
BUG_ON(spin_is_locked(&gl->gl_spin));
glock_free(gl);
rv = 1;
goto out;
}
- write_unlock(&gl_hash_locks[gl->gl_hash]);
+ write_unlock(gl_lock_addr(gl->gl_hash));
out:
return rv;
}
@@ -243,9 +294,9 @@ static struct gfs2_glock *gfs2_glock_find(const struct gfs2_sbd *sdp,
unsigned int hash = gl_hash(sdp, name);
struct gfs2_glock *gl;
- read_lock(&gl_hash_locks[hash]);
+ read_lock(gl_lock_addr(hash));
gl = search_bucket(hash, sdp, name);
- read_unlock(&gl_hash_locks[hash]);
+ read_unlock(gl_lock_addr(hash));
return gl;
}
@@ -272,9 +323,9 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
unsigned int hash = gl_hash(sdp, &name);
int error;
- read_lock(&gl_hash_locks[hash]);
+ read_lock(gl_lock_addr(hash));
gl = search_bucket(hash, sdp, &name);
- read_unlock(&gl_hash_locks[hash]);
+ read_unlock(gl_lock_addr(hash));
if (gl || !create) {
*glp = gl;
@@ -316,15 +367,15 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
if (error)
goto fail_aspace;
- write_lock(&gl_hash_locks[hash]);
+ write_lock(gl_lock_addr(hash));
tmp = search_bucket(hash, sdp, &name);
if (tmp) {
- write_unlock(&gl_hash_locks[hash]);
+ write_unlock(gl_lock_addr(hash));
glock_free(gl);
gl = tmp;
} else {
list_add_tail(&gl->gl_list, &gl_hash_table[hash].hb_list);
- write_unlock(&gl_hash_locks[hash]);
+ write_unlock(gl_lock_addr(hash));
}
*glp = gl;
@@ -1879,12 +1930,12 @@ static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
memset(&plug.gl_flags, 0, sizeof(unsigned long));
set_bit(GLF_PLUG, &plug.gl_flags);
- write_lock(&gl_hash_locks[hash]);
+ write_lock(gl_lock_addr(hash));
list_add(&plug.gl_list, &gl_hash_table[hash].hb_list);
- write_unlock(&gl_hash_locks[hash]);
+ write_unlock(gl_lock_addr(hash));
for (;;) {
- write_lock(&gl_hash_locks[hash]);
+ write_lock(gl_lock_addr(hash));
for (;;) {
tmp = plug.gl_list.next;
@@ -1892,7 +1943,7 @@ static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
if (tmp == &gl_hash_table[hash].hb_list) {
list_del(&plug.gl_list);
entries = !list_empty(&gl_hash_table[hash].hb_list);
- write_unlock(&gl_hash_locks[hash]);
+ write_unlock(gl_lock_addr(hash));
return entries;
}
gl = list_entry(tmp, struct gfs2_glock, gl_list);
@@ -1911,7 +1962,7 @@ static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
break;
}
- write_unlock(&gl_hash_locks[hash]);
+ write_unlock(gl_lock_addr(hash));
examiner(gl);
}
@@ -2204,7 +2255,7 @@ static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
- read_lock(&gl_hash_locks[x]);
+ read_lock(gl_lock_addr(x));
list_for_each_entry(gl, &gl_hash_table[x].hb_list, gl_list) {
if (test_bit(GLF_PLUG, &gl->gl_flags))
@@ -2217,7 +2268,7 @@ static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
break;
}
- read_unlock(&gl_hash_locks[x]);
+ read_unlock(gl_lock_addr(x));
if (error)
break;
@@ -2231,9 +2282,13 @@ int __init gfs2_glock_init(void)
{
unsigned i;
for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
- rwlock_init(&gl_hash_locks[i]);
INIT_LIST_HEAD(&gl_hash_table[i].hb_list);
}
+#ifdef GL_HASH_LOCK_SZ
+ for(i = 0; i < GL_HASH_LOCK_SZ; i++) {
+ rwlock_init(&gl_hash_locks[i]);
+ }
+#endif
return 0;
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-30 01:55:55 +0000