xfs: extract xfs_da_buf_copy() helper function

This patch does not modify logic.

xfs_da_buf_copy() will copy one block from src xfs_buf to
dst xfs_buf, and update the block metadata in dst directly.
Signed-off-by: Zhang Tianci <zhangtianci.1997@bytedance.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

fs/xfs/libxfs/xfs_attr_leaf.c

@@ -1244,14 +1244,10 @@ xfs_attr3_leaf_to_node(
 	if (error)
 		goto out;
 
-	/* copy leaf to new buffer, update identifiers */
-	xfs_trans_buf_set_type(args->trans, bp2, XFS_BLFT_ATTR_LEAF_BUF);
-	bp2->b_ops = bp1->b_ops;
-	memcpy(bp2->b_addr, bp1->b_addr, args->geo->blksize);
-	if (xfs_has_crc(mp)) {
-		struct xfs_da3_blkinfo *hdr3 = bp2->b_addr;
-		hdr3->blkno = cpu_to_be64(xfs_buf_daddr(bp2));
-	}
+	/*
+	 * Copy leaf to new buffer and log it.
+	 */
+	xfs_da_buf_copy(bp2, bp1, args->geo->blksize);
 	xfs_trans_log_buf(args->trans, bp2, 0, args->geo->blksize - 1);
 
 	/*

fs/xfs/libxfs/xfs_da_btree.c

@@ -421,6 +421,25 @@ xfs_da3_node_read_mapped(
 	return xfs_da3_node_set_type(tp, *bpp);
 }
 
+/*
+ * Copy src directory/attr leaf/node buffer to the dst.
+ * For v5 file systems make sure the right blkno is stamped in.
+ */
+void
+xfs_da_buf_copy(
+	struct xfs_buf *dst,
+	struct xfs_buf *src,
+	size_t size)
+{
+	struct xfs_da3_blkinfo *da3 = dst->b_addr;
+
+	memcpy(dst->b_addr, src->b_addr, size);
+	dst->b_ops = src->b_ops;
+	xfs_trans_buf_copy_type(dst, src);
+	if (xfs_has_crc(dst->b_mount))
+		da3->blkno = cpu_to_be64(xfs_buf_daddr(dst));
+}
+
 /*========================================================================
  * Routines used for growing the Btree.
  *========================================================================*/
@@ -690,12 +709,6 @@ xfs_da3_root_split(
 		btree = icnodehdr.btree;
 		size = (int)((char *)&btree[icnodehdr.count] - (char *)oldroot);
 		level = icnodehdr.level;
-
-		/*
-		 * we are about to copy oldroot to bp, so set up the type
-		 * of bp while we know exactly what it will be.
-		 */
-		xfs_trans_buf_set_type(tp, bp, XFS_BLFT_DA_NODE_BUF);
 	} else {
 		struct xfs_dir3_icleaf_hdr leafhdr;
 
@@ -707,31 +720,17 @@ xfs_da3_root_split(
 		size = (int)((char *)&leafhdr.ents[leafhdr.count] -
 			(char *)leaf);
 		level = 0;
-
-		/*
-		 * we are about to copy oldroot to bp, so set up the type
-		 * of bp while we know exactly what it will be.
-		 */
-		xfs_trans_buf_set_type(tp, bp, XFS_BLFT_DIR_LEAFN_BUF);
 	}
 
 	/*
-	 * we can copy most of the information in the node from one block to
-	 * another, but for CRC enabled headers we have to make sure that the
-	 * block specific identifiers are kept intact. We update the buffer
-	 * directly for this.
+	 * Copy old root to new buffer and log it.
 	 */
-	memcpy(node, oldroot, size);
-	if (oldroot->hdr.info.magic == cpu_to_be16(XFS_DA3_NODE_MAGIC) ||
-	    oldroot->hdr.info.magic == cpu_to_be16(XFS_DIR3_LEAFN_MAGIC)) {
-		struct xfs_da3_intnode *node3 = (struct xfs_da3_intnode *)node;
-
-		node3->hdr.info.blkno = cpu_to_be64(xfs_buf_daddr(bp));
-	}
+	xfs_da_buf_copy(bp, blk1->bp, size);
 	xfs_trans_log_buf(tp, bp, 0, size - 1);
 
-	bp->b_ops = blk1->bp->b_ops;
-	xfs_trans_buf_copy_type(bp, blk1->bp);
+	/*
+	 * Update blk1 to point to new buffer.
+	 */
 	blk1->bp = bp;
 	blk1->blkno = blkno;
 
@@ -1220,21 +1219,14 @@ xfs_da3_root_join(
 	xfs_da_blkinfo_onlychild_validate(bp->b_addr, oldroothdr.level);
 
 	/*
-	 * This could be copying a leaf back into the root block in the case of
-	 * there only being a single leaf block left in the tree. Hence we have
-	 * to update the b_ops pointer as well to match the buffer type change
-	 * that could occur. For dir3 blocks we also need to update the block
-	 * number in the buffer header.
+	 * Copy child to root buffer and log it.
 	 */
-	memcpy(root_blk->bp->b_addr, bp->b_addr, args->geo->blksize);
-	root_blk->bp->b_ops = bp->b_ops;
-	xfs_trans_buf_copy_type(root_blk->bp, bp);
-	if (oldroothdr.magic == XFS_DA3_NODE_MAGIC) {
-		struct xfs_da3_blkinfo *da3 = root_blk->bp->b_addr;
-		da3->blkno = cpu_to_be64(xfs_buf_daddr(root_blk->bp));
-	}
+	xfs_da_buf_copy(root_blk->bp, bp, args->geo->blksize);
 	xfs_trans_log_buf(args->trans, root_blk->bp, 0,
 			  args->geo->blksize - 1);
+	/*
+	 * Now we can drop the child buffer.
+	 */
 	error = xfs_da_shrink_inode(args, child, bp);
 	return error;
 }
@@ -2316,14 +2308,8 @@ xfs_da3_swap_lastblock(
 		return error;
 	/*
 	 * Copy the last block into the dead buffer and log it.
-	 * On CRC-enabled file systems, also update the stamped in blkno.
 	 */
-	memcpy(dead_buf->b_addr, last_buf->b_addr, args->geo->blksize);
-	if (xfs_has_crc(mp)) {
-		struct xfs_da3_blkinfo *da3 = dead_buf->b_addr;
-
-		da3->blkno = cpu_to_be64(xfs_buf_daddr(dead_buf));
-	}
+	xfs_da_buf_copy(dead_buf, last_buf, args->geo->blksize);
 	xfs_trans_log_buf(tp, dead_buf, 0, args->geo->blksize - 1);
 	dead_info = dead_buf->b_addr;
 

fs/xfs/libxfs/xfs_da_btree.h

@@ -219,6 +219,8 @@ int	xfs_da_reada_buf(struct xfs_inode *dp, xfs_dablk_t bno,
 		const struct xfs_buf_ops *ops);
 int	xfs_da_shrink_inode(xfs_da_args_t *args, xfs_dablk_t dead_blkno,
 					  struct xfs_buf *dead_buf);
+void	xfs_da_buf_copy(struct xfs_buf *dst, struct xfs_buf *src,
+			size_t size);
 
 uint xfs_da_hashname(const uint8_t *name_string, int name_length);
 enum xfs_dacmp xfs_da_compname(struct xfs_da_args *args,