xfs: move log recovery buffer cancellation code to xfs_buf_item_recover.c

Move the helpers that handle incore buffer cancellation records to
xfs_buf_item_recover.c since they're not directly related to the main
log recovery machinery.  No functional changes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 104 insertions, 0 deletions

diff --git a/fs/xfs/xfs_buf_item_recover.c b/fs/xfs/xfs_buf_item_recover.c
index 4ba2e27a15ca..04faa7310c4f 100644
--- a/fs/xfs/xfs_buf_item_recover.c
+++ b/fs/xfs/xfs_buf_item_recover.c
@@ -24,6 +24,110 @@
 #include "xfs_quota.h"
 
 /*
+ * This structure is used during recovery to record the buf log items which
+ * have been canceled and should not be replayed.
+ */
+struct xfs_buf_cancel {
+	xfs_daddr_t		bc_blkno;
+	uint			bc_len;
+	int			bc_refcount;
+	struct list_head	bc_list;
+};
+
+static struct xfs_buf_cancel *
+xlog_find_buffer_cancelled(
+	struct xlog		*log,
+	xfs_daddr_t		blkno,
+	uint			len)
+{
+	struct list_head	*bucket;
+	struct xfs_buf_cancel	*bcp;
+
+	if (!log->l_buf_cancel_table)
+		return NULL;
+
+	bucket = XLOG_BUF_CANCEL_BUCKET(log, blkno);
+	list_for_each_entry(bcp, bucket, bc_list) {
+		if (bcp->bc_blkno == blkno && bcp->bc_len == len)
+			return bcp;
+	}
+
+	return NULL;
+}
+
+static bool
+xlog_add_buffer_cancelled(
+	struct xlog		*log,
+	xfs_daddr_t		blkno,
+	uint			len)
+{
+	struct xfs_buf_cancel	*bcp;
+
+	/*
+	 * If we find an existing cancel record, this indicates that the buffer
+	 * was cancelled multiple times.  To ensure that during pass 2 we keep
+	 * the record in the table until we reach its last occurrence in the
+	 * log, a reference count is kept to tell how many times we expect to
+	 * see this record during the second pass.
+	 */
+	bcp = xlog_find_buffer_cancelled(log, blkno, len);
+	if (bcp) {
+		bcp->bc_refcount++;
+		return false;
+	}
+
+	bcp = kmem_alloc(sizeof(struct xfs_buf_cancel), 0);
+	bcp->bc_blkno = blkno;
+	bcp->bc_len = len;
+	bcp->bc_refcount = 1;
+	list_add_tail(&bcp->bc_list, XLOG_BUF_CANCEL_BUCKET(log, blkno));
+	return true;
+}
+
+/*
+ * Check if there is and entry for blkno, len in the buffer cancel record table.
+ */
+bool
+xlog_is_buffer_cancelled(
+	struct xlog		*log,
+	xfs_daddr_t		blkno,
+	uint			len)
+{
+	return xlog_find_buffer_cancelled(log, blkno, len) != NULL;
+}
+
+/*
+ * Check if there is and entry for blkno, len in the buffer cancel record table,
+ * and decremented the reference count on it if there is one.
+ *
+ * Remove the cancel record once the refcount hits zero, so that if the same
+ * buffer is re-used again after its last cancellation we actually replay the
+ * changes made at that point.
+ */
+static bool
+xlog_put_buffer_cancelled(
+	struct xlog		*log,
+	xfs_daddr_t		blkno,
+	uint			len)
+{
+	struct xfs_buf_cancel	*bcp;
+
+	bcp = xlog_find_buffer_cancelled(log, blkno, len);
+	if (!bcp) {
+		ASSERT(0);
+		return false;
+	}
+
+	if (--bcp->bc_refcount == 0) {
+		list_del(&bcp->bc_list);
+		kmem_free(bcp);
+	}
+	return true;
+}
+
+/* log buffer item recovery */
+
+/*
  * Sort buffer items for log recovery.  Most buffer items should end up on the
  * buffer list and are recovered first, with the following exceptions:
  *