1 files changed, 28 insertions, 8 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 7f7be5f98f52..d1f76da6f8bf 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1028,6 +1028,11 @@ xfs_dinode_calc_crc(
 
 /*
  * Read the disk inode attributes into the in-core inode structure.
+ *
+ * If we are initialising a new inode and we are not utilising the
+ * XFS_MOUNT_IKEEP inode cluster mode, we can simple build the new inode core
+ * with a random generation number. If we are keeping inodes around, we need to
+ * read the inode cluster to get the existing generation number off disk.
  */
 int
 xfs_iread(
@@ -1047,6 +1052,22 @@ xfs_iread(
         if (error)
                 return error;
 
+        /* shortcut IO on inode allocation if possible */
+        if ((iget_flags & XFS_IGET_CREATE) &&
+            !(mp->m_flags & XFS_MOUNT_IKEEP)) {
+                /* initialise the on-disk inode core */
+                memset(&ip->i_d, 0, sizeof(ip->i_d));
+                ip->i_d.di_magic = XFS_DINODE_MAGIC;
+                ip->i_d.di_gen = prandom_u32();
+                if (xfs_sb_version_hascrc(&mp->m_sb)) {
+                        ip->i_d.di_version = 3;
+                        ip->i_d.di_ino = ip->i_ino;
+                        uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+                } else
+                        ip->i_d.di_version = 2;
+                return 0;
+        }
+
         /*
          * Get pointers to the on-disk inode and the buffer containing it.
          */
@@ -1133,17 +1154,16 @@ xfs_iread(
         xfs_buf_set_ref(bp, XFS_INO_REF);
 
         /*
-         * Use xfs_trans_brelse() to release the buffer containing the
-         * on-disk inode, because it was acquired with xfs_trans_read_buf()
-         * in xfs_imap_to_bp() above.  If tp is NULL, this is just a normal
+         * Use xfs_trans_brelse() to release the buffer containing the on-disk
+         * inode, because it was acquired with xfs_trans_read_buf() in
+         * xfs_imap_to_bp() above.  If tp is NULL, this is just a normal
          * brelse().  If we're within a transaction, then xfs_trans_brelse()
          * will only release the buffer if it is not dirty within the
          * transaction.  It will be OK to release the buffer in this case,
-         * because inodes on disk are never destroyed and we will be
-         * locking the new in-core inode before putting it in the hash
-         * table where other processes can find it.  Thus we don't have
-         * to worry about the inode being changed just because we released
-         * the buffer.
+         * because inodes on disk are never destroyed and we will be locking the
+         * new in-core inode before putting it in the cache where other
+         * processes can find it.  Thus we don't have to worry about the inode
+         * being changed just because we released the buffer.
          */
  out_brelse:
         xfs_trans_brelse(tp, bp);