xfs: spilt xfs_dialloc() into 2 functions

This patch explicitly separates free inode chunk allocation and
inode allocation into two individual high level operations.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 15 insertions, 5 deletions

diff --git a/fs/xfs/libxfs/xfs_ialloc.h b/fs/xfs/libxfs/xfs_ialloc.h
index 13810ffe4af9..3511086a7ae1 100644
--- a/fs/xfs/libxfs/xfs_ialloc.h
+++ b/fs/xfs/libxfs/xfs_ialloc.h
@@ -37,16 +37,26 @@ xfs_make_iptr(struct xfs_mount *mp, struct xfs_buf *b, int o)
  * Mode is used to tell whether the new inode will need space, and whether
  * it is a directory.
  *
- * Once we successfully pick an inode its number is returned and the
- * on-disk data structures are updated.  The inode itself is not read
- * in, since doing so would break ordering constraints with xfs_reclaim.
+ * There are two phases to inode allocation: selecting an AG and ensuring
+ * that it contains free inodes, followed by allocating one of the free
+ * inodes. xfs_dialloc_select_ag() does the former and returns a locked AGI
+ * to the caller, ensuring that followup call to xfs_dialloc_ag() will
+ * have free inodes to allocate from. xfs_dialloc_ag() will return the inode
+ * number of the free inode we allocated.
  */
 int					/* error */
-xfs_dialloc(
+xfs_dialloc_select_ag(
 	struct xfs_trans **tpp,		/* double pointer of transaction */
 	xfs_ino_t	parent,		/* parent inode (directory) */
 	umode_t		mode,		/* mode bits for new inode */
-	xfs_ino_t	*inop);		/* inode number allocated */
+	struct xfs_buf	**IO_agbp);
+
+int
+xfs_dialloc_ag(
+	struct xfs_trans	*tp,
+	struct xfs_buf		*agbp,
+	xfs_ino_t		parent,
+	xfs_ino_t		*inop);
 
 /*
  * Free disk inode.  Carefully avoids touching the incore inode, all