[PATCH 02/25] xfs: report shared extents in getfsmapx

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

Cross-reference the reverse mapping data with the refcount btree to find
out which extents are shared.

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 fs/xfs/xfs_fsmap.c |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)


diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
index a167acb..2eca7b9 100644
--- a/fs/xfs/xfs_fsmap.c
+++ b/fs/xfs/xfs_fsmap.c
@@ -37,6 +37,8 @@
 #include "xfs_alloc.h"
 #include "xfs_bit.h"
 #include "xfs_fsmap.h"
+#include "xfs_refcount.h"
+#include "xfs_refcount_btree.h"
 
 /* getfsmap query state */
 struct xfs_getfsmap_info {
@@ -99,6 +101,42 @@ xfs_getfsmap_rec_before_low_key(
        return false;
 }
 
+/* Decide if this mapping is shared. */
+STATIC int
+xfs_getfsmap_is_shared(
+       struct xfs_mount                *mp,
+       struct xfs_getfsmap_info        *info,
+       struct xfs_rmap_irec            *rec,
+       bool                            *stat)
+{
+       struct xfs_btree_cur            *cur;
+       xfs_agblock_t                   fbno;
+       xfs_extlen_t                    flen;
+       int                             error;
+
+       *stat = false;
+       if (!xfs_sb_version_hasreflink(&mp->m_sb))
+               return 0;
+       /* rt files will have agno set to NULLAGNUMBER */
+       if (info->agno == NULLAGNUMBER)
+               return 0;
+
+       /* Are there any shared blocks here? */
+       flen = 0;
+       cur = xfs_refcountbt_init_cursor(mp, NULL, info->agbp,
+                       info->agno, NULL);
+
+       error = xfs_refcount_find_shared(cur, rec->rm_startblock,
+                       rec->rm_blockcount, &fbno, &flen, false);
+
+       xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
+       if (error)
+               return error;
+
+       *stat = flen > 0;
+       return 0;
+}
+
 /*
  * Format a reverse mapping for getfsmap, having translated rm_startblock
  * into the appropriate daddr units.
@@ -112,6 +150,7 @@ xfs_getfsmap_helper(
 {
        struct getfsmap                 fmv;
        xfs_daddr_t                     key_end;
+       bool                            shared;
        int                             error;
 
        /*
@@ -221,6 +260,13 @@ xfs_getfsmap_helper(
                fmv.fmv_oflags |= FMV_OF_ATTR_FORK;
        if (rec->rm_flags & XFS_RMAP_BMBT_BLOCK)
                fmv.fmv_oflags |= FMV_OF_EXTENT_MAP;
+       if (fmv.fmv_oflags == 0) {
+               error = xfs_getfsmap_is_shared(mp, info, rec, &shared);
+               if (error)
+                       return error;
+               if (shared)
+                       fmv.fmv_oflags |= FMV_OF_SHARED;
+       }
        error = info->formatter(&fmv, info->format_arg);
        if (error)
                return error;