1 files changed, 198 insertions, 116 deletions

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 19eb0b7a3e58..7fc54725c5f6 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -32,6 +32,61 @@ static inline struct xfs_buf_log_item *BUF_ITEM(struct xfs_log_item *lip)
 	return container_of(lip, struct xfs_buf_log_item, bli_item);
 }
 
+static void
+xfs_buf_item_get_format(
+	struct xfs_buf_log_item	*bip,
+	int			count)
+{
+	ASSERT(bip->bli_formats == NULL);
+	bip->bli_format_count = count;
+
+	if (count == 1) {
+		bip->bli_formats = &bip->__bli_format;
+		return;
+	}
+
+	bip->bli_formats = kzalloc(count * sizeof(struct xfs_buf_log_format),
+				GFP_KERNEL | __GFP_NOFAIL);
+}
+
+static void
+xfs_buf_item_free_format(
+	struct xfs_buf_log_item	*bip)
+{
+	if (bip->bli_formats != &bip->__bli_format) {
+		kfree(bip->bli_formats);
+		bip->bli_formats = NULL;
+	}
+}
+
+static void
+xfs_buf_item_free(
+	struct xfs_buf_log_item	*bip)
+{
+	xfs_buf_item_free_format(bip);
+	kvfree(bip->bli_item.li_lv_shadow);
+	kmem_cache_free(xfs_buf_item_cache, bip);
+}
+
+/*
+ * xfs_buf_item_relse() is called when the buf log item is no longer needed.
+ */
+static void
+xfs_buf_item_relse(
+	struct xfs_buf_log_item	*bip)
+{
+	struct xfs_buf		*bp = bip->bli_buf;
+
+	trace_xfs_buf_item_relse(bp, _RET_IP_);
+
+	ASSERT(!test_bit(XFS_LI_IN_AIL, &bip->bli_item.li_flags));
+	ASSERT(atomic_read(&bip->bli_refcount) == 0);
+
+	bp->b_log_item = NULL;
+	xfs_buf_rele(bp);
+	xfs_buf_item_free(bip);
+}
+
 /* Is this log iovec plausibly large enough to contain the buffer log format? */
 bool
 xfs_buf_log_check_iovec(
@@ -104,6 +159,25 @@ xfs_buf_item_size_segment(
 }
 
 /*
+ * Compute the worst case log item overhead for an invalidated buffer with the
+ * given map count and block size.
+ */
+unsigned int
+xfs_buf_inval_log_space(
+	unsigned int	map_count,
+	unsigned int	blocksize)
+{
+	unsigned int	chunks = DIV_ROUND_UP(blocksize, XFS_BLF_CHUNK);
+	unsigned int	bitmap_size = DIV_ROUND_UP(chunks, NBWORD);
+	unsigned int	ret =
+		offsetof(struct xfs_buf_log_format, blf_data_map) +
+			(bitmap_size * sizeof_field(struct xfs_buf_log_format,
+						    blf_data_map[0]));
+
+	return ret * map_count;
+}
+
+/*
  * Return the number of log iovecs and space needed to log the given buf log
  * item.
  *
@@ -371,6 +445,42 @@ xfs_buf_item_pin(
 }
 
 /*
+ * For a stale BLI, process all the necessary completions that must be
+ * performed when the final BLI reference goes away. The buffer will be
+ * referenced and locked here - we return to the caller with the buffer still
+ * referenced and locked for them to finalise processing of the buffer.
+ */
+static void
+xfs_buf_item_finish_stale(
+	struct xfs_buf_log_item	*bip)
+{
+	struct xfs_buf		*bp = bip->bli_buf;
+	struct xfs_log_item	*lip = &bip->bli_item;
+
+	ASSERT(bip->bli_flags & XFS_BLI_STALE);
+	ASSERT(xfs_buf_islocked(bp));
+	ASSERT(bp->b_flags & XBF_STALE);
+	ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
+	ASSERT(list_empty(&lip->li_trans));
+	ASSERT(!bp->b_transp);
+
+	if (bip->bli_flags & XFS_BLI_STALE_INODE) {
+		xfs_buf_item_done(bp);
+		xfs_buf_inode_iodone(bp);
+		ASSERT(list_empty(&bp->b_li_list));
+		return;
+	}
+
+	/*
+	 * We may or may not be on the AIL here, xfs_trans_ail_delete() will do
+	 * the right thing regardless of the situation in which we are called.
+	 */
+	xfs_trans_ail_delete(lip, SHUTDOWN_LOG_IO_ERROR);
+	xfs_buf_item_relse(bip);
+	ASSERT(bp->b_log_item == NULL);
+}
+
+/*
  * This is called to unpin the buffer associated with the buf log item which was
  * previously pinned with a call to xfs_buf_item_pin().  We enter this function
  * with a buffer pin count, a buffer reference and a BLI reference.
@@ -419,13 +529,6 @@ xfs_buf_item_unpin(
 	}
 
 	if (stale) {
-		ASSERT(bip->bli_flags & XFS_BLI_STALE);
-		ASSERT(xfs_buf_islocked(bp));
-		ASSERT(bp->b_flags & XBF_STALE);
-		ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
-		ASSERT(list_empty(&lip->li_trans));
-		ASSERT(!bp->b_transp);
-
 		trace_xfs_buf_item_unpin_stale(bip);
 
 		/*
@@ -436,22 +539,7 @@ xfs_buf_item_unpin(
 		 * processing is complete.
 		 */
 		xfs_buf_rele(bp);
-
-		/*
-		 * If we get called here because of an IO error, we may or may
-		 * not have the item on the AIL. xfs_trans_ail_delete() will
-		 * take care of that situation. xfs_trans_ail_delete() drops
-		 * the AIL lock.
-		 */
-		if (bip->bli_flags & XFS_BLI_STALE_INODE) {
-			xfs_buf_item_done(bp);
-			xfs_buf_inode_iodone(bp);
-			ASSERT(list_empty(&bp->b_li_list));
-		} else {
-			xfs_trans_ail_delete(lip, SHUTDOWN_LOG_IO_ERROR);
-			xfs_buf_item_relse(bp);
-			ASSERT(bp->b_log_item == NULL);
-		}
+		xfs_buf_item_finish_stale(bip);
 		xfs_buf_relse(bp);
 		return;
 	}
@@ -524,43 +612,42 @@ xfs_buf_item_push(
  * Drop the buffer log item refcount and take appropriate action. This helper
  * determines whether the bli must be freed or not, since a decrement to zero
  * does not necessarily mean the bli is unused.
- *
- * Return true if the bli is freed, false otherwise.
  */
-bool
+void
 xfs_buf_item_put(
 	struct xfs_buf_log_item	*bip)
 {
-	struct xfs_log_item	*lip = &bip->bli_item;
-	bool			aborted;
-	bool			dirty;
+
+	ASSERT(xfs_buf_islocked(bip->bli_buf));
 
 	/* drop the bli ref and return if it wasn't the last one */
 	if (!atomic_dec_and_test(&bip->bli_refcount))
-		return false;
+		return;
 
-	/*
-	 * We dropped the last ref and must free the item if clean or aborted.
-	 * If the bli is dirty and non-aborted, the buffer was clean in the
-	 * transaction but still awaiting writeback from previous changes. In
-	 * that case, the bli is freed on buffer writeback completion.
-	 */
-	aborted = test_bit(XFS_LI_ABORTED, &lip->li_flags) ||
-			xlog_is_shutdown(lip->li_log);
-	dirty = bip->bli_flags & XFS_BLI_DIRTY;
-	if (dirty && !aborted)
-		return false;
+	/* If the BLI is in the AIL, then it is still dirty and in use */
+	if (test_bit(XFS_LI_IN_AIL, &bip->bli_item.li_flags)) {
+		ASSERT(bip->bli_flags & XFS_BLI_DIRTY);
+		return;
+	}
 
 	/*
-	 * The bli is aborted or clean. An aborted item may be in the AIL
-	 * regardless of dirty state.  For example, consider an aborted
-	 * transaction that invalidated a dirty bli and cleared the dirty
-	 * state.
+	 * In shutdown conditions, we can be asked to free a dirty BLI that
+	 * isn't in the AIL. This can occur due to a checkpoint aborting a BLI
+	 * instead of inserting it into the AIL at checkpoint IO completion. If
+	 * there's another bli reference (e.g. a btree cursor holds a clean
+	 * reference) and it is released via xfs_trans_brelse(), we can get here
+	 * with that aborted, dirty BLI. In this case, it is safe to free the
+	 * dirty BLI immediately, as it is not in the AIL and there are no
+	 * other references to it.
+	 *
+	 * We should never get here with a stale BLI via that path as
+	 * xfs_trans_brelse() specifically holds onto stale buffers rather than
+	 * releasing them.
 	 */
-	if (aborted)
-		xfs_trans_ail_delete(lip, 0);
-	xfs_buf_item_relse(bip->bli_buf);
-	return true;
+	ASSERT(!(bip->bli_flags & XFS_BLI_DIRTY) ||
+			test_bit(XFS_LI_ABORTED, &bip->bli_item.li_flags));
+	ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
+	xfs_buf_item_relse(bip);
 }
 
 /*
@@ -581,6 +668,15 @@ xfs_buf_item_put(
  * if necessary but do not unlock the buffer.  This is for support of
  * xfs_trans_bhold(). Make sure the XFS_BLI_HOLD field is cleared if we don't
  * free the item.
+ *
+ * If the XFS_BLI_STALE flag is set, the last reference to the BLI *must*
+ * perform a completion abort of any objects attached to the buffer for IO
+ * tracking purposes. This generally only happens in shutdown situations,
+ * normally xfs_buf_item_unpin() will drop the last BLI reference and perform
+ * completion processing. However, because transaction completion can race with
+ * checkpoint completion during a shutdown, this release context may end up
+ * being the last active reference to the BLI and so needs to perform this
+ * cleanup.
  */
 STATIC void
 xfs_buf_item_release(
@@ -588,18 +684,19 @@ xfs_buf_item_release(
 {
 	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);
 	struct xfs_buf		*bp = bip->bli_buf;
-	bool			released;
 	bool			hold = bip->bli_flags & XFS_BLI_HOLD;
 	bool			stale = bip->bli_flags & XFS_BLI_STALE;
-#if defined(DEBUG) || defined(XFS_WARN)
-	bool			ordered = bip->bli_flags & XFS_BLI_ORDERED;
-	bool			dirty = bip->bli_flags & XFS_BLI_DIRTY;
 	bool			aborted = test_bit(XFS_LI_ABORTED,
 						   &lip->li_flags);
+	bool			dirty = bip->bli_flags & XFS_BLI_DIRTY;
+#if defined(DEBUG) || defined(XFS_WARN)
+	bool			ordered = bip->bli_flags & XFS_BLI_ORDERED;
 #endif
 
 	trace_xfs_buf_item_release(bip);
 
+	ASSERT(xfs_buf_islocked(bp));
+
 	/*
 	 * The bli dirty state should match whether the blf has logged segments
 	 * except for ordered buffers, where only the bli should be dirty.
@@ -615,16 +712,56 @@ xfs_buf_item_release(
 	bp->b_transp = NULL;
 	bip->bli_flags &= ~(XFS_BLI_LOGGED | XFS_BLI_HOLD | XFS_BLI_ORDERED);
 
+	/* If there are other references, then we have nothing to do. */
+	if (!atomic_dec_and_test(&bip->bli_refcount))
+		goto out_release;
+
+	/*
+	 * Stale buffer completion frees the BLI, unlocks and releases the
+	 * buffer. Neither the BLI or buffer are safe to reference after this
+	 * call, so there's nothing more we need to do here.
+	 *
+	 * If we get here with a stale buffer and references to the BLI remain,
+	 * we must not unlock the buffer as the last BLI reference owns lock
+	 * context, not us.
+	 */
+	if (stale) {
+		xfs_buf_item_finish_stale(bip);
+		xfs_buf_relse(bp);
+		ASSERT(!hold);
+		return;
+	}
+
+	/*
+	 * Dirty or clean, aborted items are done and need to be removed from
+	 * the AIL and released. This frees the BLI, but leaves the buffer
+	 * locked and referenced.
+	 */
+	if (aborted || xlog_is_shutdown(lip->li_log)) {
+		ASSERT(list_empty(&bip->bli_buf->b_li_list));
+		xfs_buf_item_done(bp);
+		goto out_release;
+	}
+
+	/*
+	 * Clean, unreferenced BLIs can be immediately freed, leaving the buffer
+	 * locked and referenced.
+	 *
+	 * Dirty, unreferenced BLIs *must* be in the AIL awaiting writeback.
+	 */
+	if (!dirty)
+		xfs_buf_item_relse(bip);
+	else
+		ASSERT(test_bit(XFS_LI_IN_AIL, &lip->li_flags));
+
+	/* Not safe to reference the BLI from here */
+out_release:
 	/*
-	 * Unref the item and unlock the buffer unless held or stale. Stale
-	 * buffers remain locked until final unpin unless the bli is freed by
-	 * the unref call. The latter implies shutdown because buffer
-	 * invalidation dirties the bli and transaction.
+	 * If we get here with a stale buffer, we must not unlock the
+	 * buffer as the last BLI reference owns lock context, not us.
 	 */
-	released = xfs_buf_item_put(bip);
-	if (hold || (stale && !released))
+	if (stale || hold)
 		return;
-	ASSERT(!stale || aborted);
 	xfs_buf_relse(bp);
 }
 
@@ -710,33 +847,6 @@ static const struct xfs_item_ops xfs_buf_item_ops = {
 	.iop_push	= xfs_buf_item_push,
 };
 
-STATIC void
-xfs_buf_item_get_format(
-	struct xfs_buf_log_item	*bip,
-	int			count)
-{
-	ASSERT(bip->bli_formats == NULL);
-	bip->bli_format_count = count;
-
-	if (count == 1) {
-		bip->bli_formats = &bip->__bli_format;
-		return;
-	}
-
-	bip->bli_formats = kzalloc(count * sizeof(struct xfs_buf_log_format),
-				GFP_KERNEL | __GFP_NOFAIL);
-}
-
-STATIC void
-xfs_buf_item_free_format(
-	struct xfs_buf_log_item	*bip)
-{
-	if (bip->bli_formats != &bip->__bli_format) {
-		kfree(bip->bli_formats);
-		bip->bli_formats = NULL;
-	}
-}
-
 /*
  * Allocate a new buf log item to go with the given buffer.
  * Set the buffer's b_log_item field to point to the new
@@ -957,34 +1067,6 @@ xfs_buf_item_dirty_format(
 	return false;
 }
 
-STATIC void
-xfs_buf_item_free(
-	struct xfs_buf_log_item	*bip)
-{
-	xfs_buf_item_free_format(bip);
-	kvfree(bip->bli_item.li_lv_shadow);
-	kmem_cache_free(xfs_buf_item_cache, bip);
-}
-
-/*
- * xfs_buf_item_relse() is called when the buf log item is no longer needed.
- */
-void
-xfs_buf_item_relse(
-	struct xfs_buf	*bp)
-{
-	struct xfs_buf_log_item	*bip = bp->b_log_item;
-
-	trace_xfs_buf_item_relse(bp, _RET_IP_);
-	ASSERT(!test_bit(XFS_LI_IN_AIL, &bip->bli_item.li_flags));
-
-	if (atomic_read(&bip->bli_refcount))
-		return;
-	bp->b_log_item = NULL;
-	xfs_buf_rele(bp);
-	xfs_buf_item_free(bip);
-}
-
 void
 xfs_buf_item_done(
 	struct xfs_buf		*bp)
@@ -1004,5 +1086,5 @@ xfs_buf_item_done(
 	xfs_trans_ail_delete(&bp->b_log_item->bli_item,
 			     (bp->b_flags & _XBF_LOGRECOVERY) ? 0 :
 			     SHUTDOWN_CORRUPT_INCORE);
-	xfs_buf_item_relse(bp);
+	xfs_buf_item_relse(bp->b_log_item);
 }