xfs: hoist the code that moves the incore inode fork broot memory

Whenever we change the size of the memory buffer holding an inode fork
btree root block, we have to copy the contents over.  Refactor all this
into a single function that handles both, in preparation for making
xfs_iroot_realloc more generic.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

1 files changed, 57 insertions, 42 deletions

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index a14a9284cecb..832c8ec8bea6 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -364,6 +364,50 @@ xfs_iroot_free(
 	ifp->if_broot = NULL;
 }
 
+/* Move the bmap btree root from one incore buffer to another. */
+static void
+xfs_ifork_move_broot(
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_btree_block	*dst_broot,
+	size_t			dst_bytes,
+	struct xfs_btree_block	*src_broot,
+	size_t			src_bytes,
+	unsigned int		numrecs)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	void			*dptr;
+	void			*sptr;
+
+	ASSERT(xfs_bmap_bmdr_space(src_broot) <= XFS_IFORK_SIZE(ip, whichfork));
+
+	/*
+	 * We always have to move the pointers because they are not butted
+	 * against the btree block header.
+	 */
+	if (numrecs) {
+		sptr = xfs_bmap_broot_ptr_addr(mp, src_broot, 1, src_bytes);
+		dptr = xfs_bmap_broot_ptr_addr(mp, dst_broot, 1, dst_bytes);
+		memmove(dptr, sptr, numrecs * sizeof(xfs_fsblock_t));
+	}
+
+	if (src_broot == dst_broot)
+		return;
+
+	/*
+	 * If the root is being totally relocated, we have to migrate the block
+	 * header and the keys that come after it.
+	 */
+	memcpy(dst_broot, src_broot, xfs_bmbt_block_len(mp));
+
+	/* Now copy the keys, which come right after the header. */
+	if (numrecs) {
+		sptr = xfs_bmbt_key_addr(mp, src_broot, 1);
+		dptr = xfs_bmbt_key_addr(mp, dst_broot, 1);
+		memcpy(dptr, sptr, numrecs * sizeof(struct xfs_bmbt_key));
+	}
+}
+
 /*
  * Reallocate the space for if_broot based on the number of records
  * being added or deleted as indicated in rec_diff.  Move the records
@@ -390,12 +434,11 @@ xfs_iroot_realloc(
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	int			cur_max;
-	struct xfs_ifork	*ifp;
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
 	struct xfs_btree_block	*new_broot;
 	int			new_max;
 	size_t			new_size;
-	char			*np;
-	char			*op;
+	size_t			old_size = ifp->if_broot_bytes;
 
 	/*
 	 * Handle the degenerate case quietly.
@@ -404,13 +447,12 @@ xfs_iroot_realloc(
 		return;
 	}
 
-	ifp = XFS_IFORK_PTR(ip, whichfork);
 	if (rec_diff > 0) {
 		/*
 		 * If there wasn't any memory allocated before, just
 		 * allocate it now and get out.
 		 */
-		if (ifp->if_broot_bytes == 0) {
+		if (old_size == 0) {
 			new_size = xfs_bmap_broot_space_calc(mp, rec_diff);
 			xfs_iroot_alloc(ip, whichfork, new_size);
 			return;
@@ -419,22 +461,16 @@ xfs_iroot_realloc(
 		/*
 		 * If there is already an existing if_broot, then we need
 		 * to realloc() it and shift the pointers to their new
-		 * location.  The records don't change location because
-		 * they are kept butted up against the btree block header.
+		 * location.
 		 */
-		cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
+		cur_max = xfs_bmbt_maxrecs(mp, old_size, 0);
 		new_max = cur_max + rec_diff;
 		new_size = xfs_bmap_broot_space_calc(mp, new_max);
 		ifp->if_broot = krealloc(ifp->if_broot, new_size,
 					 GFP_NOFS | __GFP_NOFAIL);
-		op = (char *)xfs_bmap_broot_ptr_addr(mp, ifp->if_broot, 1,
-						     ifp->if_broot_bytes);
-		np = (char *)xfs_bmap_broot_ptr_addr(mp, ifp->if_broot, 1,
-						     (int)new_size);
-		ifp->if_broot_bytes = (int)new_size;
-		ASSERT(xfs_bmap_bmdr_space(ifp->if_broot) <=
-			XFS_IFORK_SIZE(ip, whichfork));
-		memmove(np, op, cur_max * (uint)sizeof(xfs_fsblock_t));
+		ifp->if_broot_bytes = new_size;
+		xfs_ifork_move_broot(ip, whichfork, ifp->if_broot, new_size,
+				ifp->if_broot, old_size, cur_max);
 		return;
 	}
 
@@ -443,8 +479,8 @@ xfs_iroot_realloc(
 	 * if_broot buffer.  It must already exist.  If we go to zero
 	 * records, just get rid of the root and clear the status bit.
 	 */
-	ASSERT((ifp->if_broot != NULL) && (ifp->if_broot_bytes > 0));
-	cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
+	ASSERT((ifp->if_broot != NULL) && (old_size > 0));
+	cur_max = xfs_bmbt_maxrecs(mp, old_size, 0);
 	new_max = cur_max + rec_diff;
 	ASSERT(new_max >= 0);
 	if (new_max > 0)
@@ -456,35 +492,14 @@ xfs_iroot_realloc(
 		return;
 	}
 
-	/* First copy over the btree block header. */
+	/* Reallocate the btree root and move the contents. */
 	new_broot = kmem_alloc(new_size, KM_NOFS);
-	memcpy(new_broot, ifp->if_broot, xfs_bmbt_block_len(ip->i_mount));
-
-	/*
-	 * Only copy the keys and pointers if there are any.
-	 */
-	if (new_max > 0) {
-		/*
-		 * First copy the keys.
-		 */
-		op = (char *)xfs_bmbt_key_addr(mp, ifp->if_broot, 1);
-		np = (char *)xfs_bmbt_key_addr(mp, new_broot, 1);
-		memcpy(np, op, new_max * (uint)sizeof(xfs_bmbt_key_t));
+	xfs_ifork_move_broot(ip, whichfork, new_broot, new_size, ifp->if_broot,
+			old_size, new_max);
 
-		/*
-		 * Then copy the pointers.
-		 */
-		op = (char *)xfs_bmap_broot_ptr_addr(mp, ifp->if_broot, 1,
-						     ifp->if_broot_bytes);
-		np = (char *)xfs_bmap_broot_ptr_addr(mp, new_broot, 1,
-						     (int)new_size);
-		memcpy(np, op, new_max * (uint)sizeof(xfs_fsblock_t));
-	}
 	kmem_free(ifp->if_broot);
 	ifp->if_broot = new_broot;
 	ifp->if_broot_bytes = (int)new_size;
-	ASSERT(xfs_bmap_bmdr_space(ifp->if_broot) <=
-		XFS_IFORK_SIZE(ip, whichfork));
 	return;
 }