[1/8] xfs: tidy up xfs_iroot_realloc

Commit Message

Darrick J. Wong Dec. 19, 2024, 7:21 p.m. UTC

From: Darrick J. Wong <[e-mail]>

Tidy up this function a bit before we start refactoring the memory
handling and move the function to the bmbt code.

Signed-off-by: "Darrick J. Wong" <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
---
 fs/xfs/libxfs/xfs_inode_fork.c |   83 +++++++++++++++++++---------------------
 1 file changed, 40 insertions(+), 43 deletions(-)

Patch

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 1158ca48626b71..7f865479c4159f 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -382,33 +382,32 @@  xfs_iformat_attr_fork(
  */
 void
 xfs_iroot_realloc(
-	xfs_inode_t		*ip,
+	struct xfs_inode	*ip,
 	int			rec_diff,
 	int			whichfork)
 {
 	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			new_size;
+	short			old_size = ifp->if_broot_bytes;
+	int			cur_max;
+	int			new_max;
 
 	/*
 	 * Handle the degenerate case quietly.
 	 */
-	if (rec_diff == 0) {
+	if (rec_diff == 0)
 		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);
 			ifp->if_broot = kmalloc(new_size,
 						GFP_KERNEL | __GFP_NOFAIL);
@@ -422,13 +421,13 @@  xfs_iroot_realloc(
 		 * location.  The records don't change location because
 		 * they are kept butted up against the btree block header.
 		 */
-		cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, false);
+		cur_max = xfs_bmbt_maxrecs(mp, old_size, false);
 		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_KERNEL | __GFP_NOFAIL);
 		op = (char *)xfs_bmap_broot_ptr_addr(mp, ifp->if_broot, 1,
-						     ifp->if_broot_bytes);
+						     old_size);
 		np = (char *)xfs_bmap_broot_ptr_addr(mp, ifp->if_broot, 1,
 						     (int)new_size);
 		ifp->if_broot_bytes = (int)new_size;
@@ -443,52 +442,50 @@  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, false);
+	ASSERT(ifp->if_broot != NULL && old_size > 0);
+	cur_max = xfs_bmbt_maxrecs(mp, old_size, false);
 	new_max = cur_max + rec_diff;
 	ASSERT(new_max >= 0);
 	if (new_max > 0)
 		new_size = xfs_bmap_broot_space_calc(mp, new_max);
 	else
 		new_size = 0;
-	if (new_size > 0) {
-		new_broot = kmalloc(new_size, GFP_KERNEL | __GFP_NOFAIL);
-		/*
-		 * First copy over the btree block header.
-		 */
-		memcpy(new_broot, ifp->if_broot,
-			xfs_bmbt_block_len(ip->i_mount));
-	} else {
-		new_broot = NULL;
+	if (new_size == 0) {
+		ifp->if_broot = NULL;
+		ifp->if_broot_bytes = 0;
+		return;
 	}
 
 	/*
-	 * Only copy the keys and pointers if there are any.
+	 * Shrink the btree root by allocating a smaller object and copying the
+	 * fields from the old object to the new object.  krealloc does nothing
+	 * if we realloc downwards.
 	 */
-	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));
+	new_broot = kmalloc(new_size, GFP_KERNEL | __GFP_NOFAIL);
+	/*
+	 * First copy over the btree block header.
+	 */
+	memcpy(new_broot, ifp->if_broot, xfs_bmbt_block_len(ip->i_mount));
+
+	/*
+	 * 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));
+
+	/*
+	 * Then copy the pointers.
+	 */
+	op = (char *)xfs_bmap_broot_ptr_addr(mp, ifp->if_broot, 1, old_size);
+	np = (char *)xfs_bmap_broot_ptr_addr(mp, new_broot, 1, (int)new_size);
+	memcpy(np, op, new_max * (uint)sizeof(xfs_fsblock_t));
 
-		/*
-		 * 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));
-	}
 	kfree(ifp->if_broot);
 	ifp->if_broot = new_broot;
 	ifp->if_broot_bytes = (int)new_size;
-	if (ifp->if_broot)
-		ASSERT(xfs_bmap_bmdr_space(ifp->if_broot) <=
-			xfs_inode_fork_size(ip, whichfork));
-	return;
+	ASSERT(xfs_bmap_bmdr_space(ifp->if_broot) <=
+	       xfs_inode_fork_size(ip, whichfork));
 }