xfs: remove stale parameter from ->iop_unpin method

The staleness of a object being unpinned can be directly derived
from the object itself - there is no need to extract it from the
object then pass it as a parameter into IOP_UNPIN().

This means we can kill the XFS_LID_BUF_STALE flag - it is set,
checked and cleared in the same places XFS_BLI_STALE flag in the
xfs_buf_log_item so it is now redundant and hence safe to remove.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 22 insertions, 28 deletions

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index aace237b4f46..240340a4727b 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -372,12 +372,12 @@ xfs_buf_item_pin(
  */
 STATIC void
 xfs_buf_item_unpin(
-        xfs_buf_log_item_t      *bip,
-        int                     stale)
+        xfs_buf_log_item_t      *bip)
 {
         struct xfs_ail  *ailp;
         xfs_buf_t       *bp;
         int             freed;
+        int             stale = bip->bli_flags & XFS_BLI_STALE;
 
         bp = bip->bli_buf;
         ASSERT(bp != NULL);
@@ -428,40 +428,34 @@ xfs_buf_item_unpin_remove(
         xfs_buf_log_item_t      *bip,
         xfs_trans_t             *tp)
 {
-        xfs_buf_t               *bp;
-        xfs_log_item_desc_t     *lidp;
-        int                     stale = 0;
-
-        bp = bip->bli_buf;
-        /*
-         * will xfs_buf_item_unpin() call xfs_buf_item_relse()?
-         */
+        /* will xfs_buf_item_unpin() call xfs_buf_item_relse()? */
         if ((atomic_read(&bip->bli_refcount) == 1) &&
             (bip->bli_flags & XFS_BLI_STALE)) {
+                /*
+                 * yes -- We can safely do some work here and then call
+                 * buf_item_unpin to do the rest because we are
+                 * are holding the buffer locked so no one else will be
+                 * able to bump up the refcount. We have to remove the
+                 * log item from the transaction as we are about to release
+                 * our reference to the buffer. If we don't, the unlock that
+                 * occurs later in the xfs_trans_uncommit() will try to
+                 * reference the buffer which we no longer have a hold on.
+                 */
+                struct xfs_log_item_desc *lidp;
+
                 ASSERT(XFS_BUF_VALUSEMA(bip->bli_buf) <= 0);
                 trace_xfs_buf_item_unpin_stale(bip);
 
-                /*
-                 * yes -- clear the xaction descriptor in-use flag
-                 * and free the chunk if required.  We can safely
-                 * do some work here and then call buf_item_unpin
-                 * to do the rest because if the if is true, then
-                 * we are holding the buffer locked so no one else
-                 * will be able to bump up the refcount.
-                 */
-                lidp = xfs_trans_find_item(tp, (xfs_log_item_t *) bip);
-                stale = lidp->lid_flags & XFS_LID_BUF_STALE;
+                lidp = xfs_trans_find_item(tp, (xfs_log_item_t *)bip);
                 xfs_trans_free_item(tp, lidp);
+
                 /*
-                 * Since the transaction no longer refers to the buffer,
-                 * the buffer should no longer refer to the transaction.
+                 * Since the transaction no longer refers to the buffer, the
+                 * buffer should no longer refer to the transaction.
                  */
-                XFS_BUF_SET_FSPRIVATE2(bp, NULL);
+                XFS_BUF_SET_FSPRIVATE2(bip->bli_buf, NULL);
         }
-
-        xfs_buf_item_unpin(bip, stale);
-
-        return;
+        xfs_buf_item_unpin(bip);
 }
 
 /*
@@ -675,7 +669,7 @@ static struct xfs_item_ops xfs_buf_item_ops = {
         .iop_format     = (void(*)(xfs_log_item_t*, xfs_log_iovec_t*))
                                         xfs_buf_item_format,
         .iop_pin        = (void(*)(xfs_log_item_t*))xfs_buf_item_pin,
-        .iop_unpin      = (void(*)(xfs_log_item_t*, int))xfs_buf_item_unpin,
+        .iop_unpin      = (void(*)(xfs_log_item_t*))xfs_buf_item_unpin,
         .iop_unpin_remove = (void(*)(xfs_log_item_t*, xfs_trans_t *))
                                         xfs_buf_item_unpin_remove,
         .iop_trylock    = (uint(*)(xfs_log_item_t*))xfs_buf_item_trylock,