iomap: don't set FIEMAP_EXTENT_MERGED for extent based filesystems

Filesystems like XFS that use extents should not set the
FIEMAP_EXTENT_MERGED flag in the fiemap extent structures.  To allow
for both behaviors for the upcoming gfs2 usage split the iomap
type field into type and flags, and only set FIEMAP_EXTENT_MERGED if
the IOMAP_F_MERGED flag is set.  The flags field will also come in
handy for future features such as shared extents on reflink-enabled
file systems.

Reported-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

2 files changed, 11 insertions, 2 deletions

diff --git a/fs/iomap.c b/fs/iomap.c
index 0342254646e3..706270f21b35 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -428,9 +428,12 @@ static int iomap_to_fiemap(struct fiemap_extent_info *fi,
                 break;
         }
 
+        if (iomap->flags & IOMAP_F_MERGED)
+                flags |= FIEMAP_EXTENT_MERGED;
+
         return fiemap_fill_next_extent(fi, iomap->offset,
                         iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0,
-                        iomap->length, flags | FIEMAP_EXTENT_MERGED);
+                        iomap->length, flags);
 
 }
 
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 3267df461012..3d70ece10313 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -19,6 +19,11 @@ struct vm_fault;
 #define IOMAP_UNWRITTEN 0x04    /* blocks allocated @blkno in unwritten state */
 
 /*
+ * Flags for iomap mappings:
+ */
+#define IOMAP_F_MERGED  0x01    /* contains multiple blocks/extents */
+
+/*
  * Magic value for blkno:
  */
 #define IOMAP_NULL_BLOCK -1LL   /* blkno is not valid */
@@ -27,7 +32,8 @@ struct iomap {
         sector_t                blkno;  /* 1st sector of mapping, 512b units */
         loff_t                  offset; /* file offset of mapping, bytes */
         u64                     length; /* length of mapping, bytes */
-        int                     type;   /* type of mapping */
+        u16                     type;   /* type of mapping */
+        u16                     flags;  /* flags for mapping */
         struct block_device     *bdev;  /* block device for I/O */
 };