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

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

Signed-off-by: Darrick J. Wong <[email protected]>
---
 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;

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