return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
}
-/*
- * xfs_buf_lru_add - add a buffer to the LRU.
- *
- * The LRU takes a new reference to the buffer so that it will only be freed
- * once the shrinker takes the buffer off the LRU.
- */
-static void
-xfs_buf_lru_add(
- struct xfs_buf *bp)
-{
- if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) {
- bp->b_lru_flags &= ~_XBF_LRU_DISPOSE;
- atomic_inc(&bp->b_hold);
- }
-}
-
-/*
- * xfs_buf_lru_del - remove a buffer from the LRU
- *
- * The unlocked check is safe here because it only occurs when there are not
- * b_lru_ref counts left on the inode under the pag->pag_buf_lock. it is there
- * to optimise the shrinker removing the buffer from the LRU and calling
- * xfs_buf_free().
- */
-static void
-xfs_buf_lru_del(
- struct xfs_buf *bp)
-{
- list_lru_del(&bp->b_target->bt_lru, &bp->b_lru);
-}
-
/*
* When we mark a buffer stale, we remove the buffer from the LRU and clear the
* b_lru_ref count so that the buffer is freed immediately when the buffer
*/
bp->b_flags &= ~_XBF_DELWRI_Q;
- atomic_set(&(bp)->b_lru_ref, 0);
- if (!(bp->b_lru_flags & _XBF_LRU_DISPOSE) &&
+ spin_lock(&bp->b_lock);
+ atomic_set(&bp->b_lru_ref, 0);
+ if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
(list_lru_del(&bp->b_target->bt_lru, &bp->b_lru)))
atomic_dec(&bp->b_hold);
ASSERT(atomic_read(&bp->b_hold) >= 1);
+ spin_unlock(&bp->b_lock);
}
static int
INIT_LIST_HEAD(&bp->b_list);
RB_CLEAR_NODE(&bp->b_rbnode);
sema_init(&bp->b_sema, 0); /* held, no waiters */
+ spin_lock_init(&bp->b_lock);
XB_SET_OWNER(bp);
bp->b_target = target;
bp->b_flags = flags;
ASSERT(atomic_read(&bp->b_hold) > 0);
if (atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock)) {
- if (!(bp->b_flags & XBF_STALE) &&
- atomic_read(&bp->b_lru_ref)) {
- xfs_buf_lru_add(bp);
+ spin_lock(&bp->b_lock);
+ if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
+ /*
+ * If the buffer is added to the LRU take a new
+ * reference to the buffer for the LRU and clear the
+ * (now stale) dispose list state flag
+ */
+ if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) {
+ bp->b_state &= ~XFS_BSTATE_DISPOSE;
+ atomic_inc(&bp->b_hold);
+ }
+ spin_unlock(&bp->b_lock);
spin_unlock(&pag->pag_buf_lock);
} else {
- xfs_buf_lru_del(bp);
+ /*
+ * most of the time buffers will already be removed from
+ * the LRU, so optimise that case by checking for the
+ * XFS_BSTATE_DISPOSE flag indicating the last list the
+ * buffer was on was the disposal list
+ */
+ if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
+ list_lru_del(&bp->b_target->bt_lru, &bp->b_lru);
+ } else {
+ ASSERT(list_empty(&bp->b_lru));
+ }
+ spin_unlock(&bp->b_lock);
+
ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
rb_erase(&bp->b_rbnode, &pag->pag_buf_tree);
spin_unlock(&pag->pag_buf_lock);
{
struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
+ struct list_head *dispose = arg;
if (atomic_read(&bp->b_hold) > 1) {
- /* need to wait */
+ /* need to wait, so skip it this pass */
trace_xfs_buf_wait_buftarg(bp, _RET_IP_);
- spin_unlock(lru_lock);
- delay(100);
- } else {
- /*
- * clear the LRU reference count so the buffer doesn't get
- * ignored in xfs_buf_rele().
- */
- atomic_set(&bp->b_lru_ref, 0);
- spin_unlock(lru_lock);
- xfs_buf_rele(bp);
+ return LRU_SKIP;
}
+ if (!spin_trylock(&bp->b_lock))
+ return LRU_SKIP;
- spin_lock(lru_lock);
- return LRU_RETRY;
+ /*
+ * clear the LRU reference count so the buffer doesn't get
+ * ignored in xfs_buf_rele().
+ */
+ atomic_set(&bp->b_lru_ref, 0);
+ bp->b_state |= XFS_BSTATE_DISPOSE;
+ list_move(item, dispose);
+ spin_unlock(&bp->b_lock);
+ return LRU_REMOVED;
}
void
xfs_wait_buftarg(
struct xfs_buftarg *btp)
{
- while (list_lru_count(&btp->bt_lru))
+ LIST_HEAD(dispose);
+ int loop = 0;
+
+ /* loop until there is nothing left on the lru list. */
+ while (list_lru_count(&btp->bt_lru)) {
list_lru_walk(&btp->bt_lru, xfs_buftarg_wait_rele,
- NULL, LONG_MAX);
+ &dispose, LONG_MAX);
+
+ while (!list_empty(&dispose)) {
+ struct xfs_buf *bp;
+ bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
+ list_del_init(&bp->b_lru);
+ xfs_buf_rele(bp);
+ }
+ if (loop++ != 0)
+ delay(100);
+ }
}
static enum lru_status
struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
struct list_head *dispose = arg;
+ /*
+ * we are inverting the lru lock/bp->b_lock here, so use a trylock.
+ * If we fail to get the lock, just skip it.
+ */
+ if (!spin_trylock(&bp->b_lock))
+ return LRU_SKIP;
/*
* Decrement the b_lru_ref count unless the value is already
* zero. If the value is already zero, we need to reclaim the
* buffer, otherwise it gets another trip through the LRU.
*/
- if (!atomic_add_unless(&bp->b_lru_ref, -1, 0))
+ if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
+ spin_unlock(&bp->b_lock);
return LRU_ROTATE;
+ }
- bp->b_lru_flags |= _XBF_LRU_DISPOSE;
+ bp->b_state |= XFS_BSTATE_DISPOSE;
list_move(item, dispose);
+ spin_unlock(&bp->b_lock);
return LRU_REMOVED;
}
#define _XBF_KMEM (1 << 21)/* backed by heap memory */
#define _XBF_DELWRI_Q (1 << 22)/* buffer on a delwri queue */
#define _XBF_COMPOUND (1 << 23)/* compound buffer */
-#define _XBF_LRU_DISPOSE (1 << 24)/* buffer being discarded */
typedef unsigned int xfs_buf_flags_t;
{ _XBF_PAGES, "PAGES" }, \
{ _XBF_KMEM, "KMEM" }, \
{ _XBF_DELWRI_Q, "DELWRI_Q" }, \
- { _XBF_COMPOUND, "COMPOUND" }, \
- { _XBF_LRU_DISPOSE, "LRU_DISPOSE" }
+ { _XBF_COMPOUND, "COMPOUND" }
+
+/*
+ * Internal state flags.
+ */
+#define XFS_BSTATE_DISPOSE (1 << 0) /* buffer being discarded */
typedef struct xfs_buftarg {
dev_t bt_dev;
* bt_lru_lock and not by b_sema
*/
struct list_head b_lru; /* lru list */
- xfs_buf_flags_t b_lru_flags; /* internal lru status flags */
+ spinlock_t b_lock; /* internal state lock */
+ unsigned int b_state; /* internal state flags */
wait_queue_head_t b_waiters; /* unpin waiters */
struct list_head b_list;
struct xfs_perag *b_pag; /* contains rbtree root */
projects / karo-tx-linux.git / commitdiff