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-rw-r--r--fs/xfs/xfs_bmap_btree.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/fs/xfs/xfs_bmap_btree.c b/fs/xfs/xfs_bmap_btree.c
index cf3bc76..aa2eadd 100644
--- a/fs/xfs/xfs_bmap_btree.c
+++ b/fs/xfs/xfs_bmap_btree.c
@@ -925,3 +925,37 @@ xfs_bmdr_maxrecs(
return blocklen / sizeof(xfs_bmdr_rec_t);
return blocklen / (sizeof(xfs_bmdr_key_t) + sizeof(xfs_bmdr_ptr_t));
}
+
+/*
+ * Change the owner of a btree format fork fo the inode passed in. Change it to
+ * the owner of that is passed in so that we can change owners before or after
+ * we switch forks between inodes. The operation that the caller is doing will
+ * determine whether is needs to change owner before or after the switch.
+ *
+ * For demand paged modification, the fork switch should be done after reading
+ * in all the blocks, modifying them and pinning them in the transaction. For
+ * modification when the buffers are already pinned in memory, the fork switch
+ * can be done before changing the owner as we won't need to validate the owner
+ * until the btree buffers are unpinned and writes can occur again.
+ */
+int
+xfs_bmbt_change_owner(
+ struct xfs_trans *tp,
+ struct xfs_inode *ip,
+ int whichfork,
+ xfs_ino_t new_owner)
+{
+ struct xfs_btree_cur *cur;
+ int error;
+
+ if (whichfork == XFS_DATA_FORK)
+ ASSERT(ip->i_d.di_format = XFS_DINODE_FMT_BTREE);
+ else
+ ASSERT(ip->i_d.di_aformat = XFS_DINODE_FMT_BTREE);
+
+ cur = xfs_bmbt_init_cursor(ip->i_mount, tp, ip, whichfork);
+ error = xfs_btree_change_owner(cur, new_owner);
+ xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
+ return error;
+}
+
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