[PATCH 45/76] libxfs: adjust refcount when unmapping file blocks

["Darrick J. Wong" <darrick.wong@xxxxxxxxxx>]

When we're unmapping blocks from a reflinked file, decrease the
refcount of the affected blocks and free the extents that are no
longer in use.

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_bmap.c     |   16 +++++++++++++---
 fs/xfs/libxfs/xfs_refcount.c |   42 ++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_refcount.h |    4 ++++
 3 files changed, 59 insertions(+), 3 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 5d1290e..6cc4aeb 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -46,6 +46,7 @@
 #include "xfs_attr_leaf.h"
 #include "xfs_filestream.h"
 #include "xfs_rmap_btree.h"
+#include "xfs_refcount.h"
 
 
 kmem_zone_t            *xfs_bmap_free_item_zone;
@@ -5144,9 +5145,18 @@ xfs_bmap_del_extent(
        /*
         * If we need to, add to list of extents to delete.
         */
-       if (do_fx)
-               xfs_bmap_add_free(mp, flist, del->br_startblock,
-                                 del->br_blockcount, NULL);
+       if (do_fx) {
+               if (xfs_is_reflink_inode(ip)) {
+                       error = xfs_refcount_put_extent(mp, tp, flist,
+                                               del->br_startblock,
+                                               del->br_blockcount, NULL);
+                       if (error)
+                               goto done;
+               } else
+                       xfs_bmap_add_free(mp, flist, del->br_startblock,
+                                         del->br_blockcount, NULL);
+       }
+
        /*
         * Adjust inode # blocks in the file.
         */
diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c
index dae6453..c9d6e5d 100644
--- a/fs/xfs/libxfs/xfs_refcount.c
+++ b/fs/xfs/libxfs/xfs_refcount.c
@@ -970,3 +970,45 @@ xfs_refcount_decrease(
        return xfs_refcountbt_adjust_refcount(mp, tp, agbp, agno, agbno,
                        aglen, -1, flist, oinfo);
 }
+
+/**
+ * xfs_refcount_put_extent() - release a range of blocks
+ *
+ * @mp: XFS mount object
+ * @tp: transaction that goes with the free operation
+ * @flist: List of blocks to be freed at the end of the transaction
+ * @fsbno: First fs block of the range to release
+ * @len: Length of range
+ * @owner: owner of the extent
+ */
+int
+xfs_refcount_put_extent(
+       struct xfs_mount        *mp,
+       struct xfs_trans        *tp,
+       struct xfs_bmap_free    *flist,
+       xfs_fsblock_t           fsbno,
+       xfs_filblks_t           fslen,
+       struct xfs_owner_info   *oinfo)
+{
+       int                     error;
+       struct xfs_buf          *agbp;
+       xfs_agnumber_t          agno;           /* allocation group number */
+       xfs_agblock_t           agbno;          /* ag start of range to free */
+       xfs_extlen_t            aglen;          /* ag length of range to free */
+
+       agno = XFS_FSB_TO_AGNO(mp, fsbno);
+       agbno = XFS_FSB_TO_AGBNO(mp, fsbno);
+       aglen = fslen;
+
+       /*
+        * Drop reference counts in the refcount tree.
+        */
+       error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
+       if (error)
+               return error;
+
+       error = xfs_refcount_decrease(mp, tp, agbp, agno, agbno, aglen, flist,
+                       oinfo);
+       xfs_trans_brelse(tp, agbp);
+       return error;
+}
diff --git a/fs/xfs/libxfs/xfs_refcount.h b/fs/xfs/libxfs/xfs_refcount.h
index 6640e3d..074d620 100644
--- a/fs/xfs/libxfs/xfs_refcount.h
+++ b/fs/xfs/libxfs/xfs_refcount.h
@@ -34,4 +34,8 @@ extern int xfs_refcount_decrease(struct xfs_mount *mp, struct 
xfs_trans *tp,
                xfs_extlen_t aglen, struct xfs_bmap_free *flist,
                struct xfs_owner_info *oinfo);
 
+extern int xfs_refcount_put_extent(struct xfs_mount *mp, struct xfs_trans *tp,
+               struct xfs_bmap_free *flist, xfs_fsblock_t fsbno,
+               xfs_filblks_t len, struct xfs_owner_info *oinfo);
+
 #endif /* __XFS_REFCOUNT_H__ */