1 files changed, 89 insertions, 2 deletions

diff --git a/fs/afs/dir_edit.c b/fs/afs/dir_edit.c
index a71bff10496b..fe223fb78111 100644
--- a/fs/afs/dir_edit.c
+++ b/fs/afs/dir_edit.c
@@ -127,10 +127,10 @@ static struct folio *afs_dir_get_folio(struct afs_vnode *vnode, pgoff_t index)
 /*
  * Scan a directory block looking for a dirent of the right name.
  */
-static int afs_dir_scan_block(union afs_xdr_dir_block *block, struct qstr *name,
+static int afs_dir_scan_block(const union afs_xdr_dir_block *block, const struct qstr *name,
 			      unsigned int blocknum)
 {
-	union afs_xdr_dirent *de;
+	const union afs_xdr_dirent *de;
 	u64 bitmap;
 	int d, len, n;
 
@@ -492,3 +492,90 @@ error:
 	clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
 	goto out_unmap;
 }
+
+/*
+ * Edit a subdirectory that has been moved between directories to update the
+ * ".." entry.
+ */
+void afs_edit_dir_update_dotdot(struct afs_vnode *vnode, struct afs_vnode *new_dvnode,
+				enum afs_edit_dir_reason why)
+{
+	union afs_xdr_dir_block *block;
+	union afs_xdr_dirent *de;
+	struct folio *folio;
+	unsigned int nr_blocks, b;
+	pgoff_t index;
+	loff_t i_size;
+	int slot;
+
+	_enter("");
+
+	i_size = i_size_read(&vnode->netfs.inode);
+	if (i_size < AFS_DIR_BLOCK_SIZE) {
+		clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
+		return;
+	}
+	nr_blocks = i_size / AFS_DIR_BLOCK_SIZE;
+
+	/* Find a block that has sufficient slots available.  Each folio
+	 * contains two or more directory blocks.
+	 */
+	for (b = 0; b < nr_blocks; b++) {
+		index = b / AFS_DIR_BLOCKS_PER_PAGE;
+		folio = afs_dir_get_folio(vnode, index);
+		if (!folio)
+			goto error;
+
+		block = kmap_local_folio(folio, b * AFS_DIR_BLOCK_SIZE - folio_pos(folio));
+
+		/* Abandon the edit if we got a callback break. */
+		if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
+			goto invalidated;
+
+		slot = afs_dir_scan_block(block, &dotdot_name, b);
+		if (slot >= 0)
+			goto found_dirent;
+
+		kunmap_local(block);
+		folio_unlock(folio);
+		folio_put(folio);
+	}
+
+	/* Didn't find the dirent to clobber.  Download the directory again. */
+	trace_afs_edit_dir(vnode, why, afs_edit_dir_update_nodd,
+			   0, 0, 0, 0, "..");
+	clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
+	goto out;
+
+found_dirent:
+	de = &block->dirents[slot];
+	de->u.vnode  = htonl(new_dvnode->fid.vnode);
+	de->u.unique = htonl(new_dvnode->fid.unique);
+
+	trace_afs_edit_dir(vnode, why, afs_edit_dir_update_dd, b, slot,
+			   ntohl(de->u.vnode), ntohl(de->u.unique), "..");
+
+	kunmap_local(block);
+	folio_unlock(folio);
+	folio_put(folio);
+	inode_set_iversion_raw(&vnode->netfs.inode, vnode->status.data_version);
+
+out:
+	_leave("");
+	return;
+
+invalidated:
+	kunmap_local(block);
+	folio_unlock(folio);
+	folio_put(folio);
+	trace_afs_edit_dir(vnode, why, afs_edit_dir_update_inval,
+			   0, 0, 0, 0, "..");
+	clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
+	goto out;
+
+error:
+	trace_afs_edit_dir(vnode, why, afs_edit_dir_update_error,
+			   0, 0, 0, 0, "..");
+	clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
+	goto out;
+}