[5/6] iomap: don't set FIEMAP_EXTENT_MERGED for extent based filesystems

Commit Message

Darrick J. Wong Aug. 25, 2016, 11:31 p.m. UTC

From: Christoph Hellwig <[e-mail]>

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 <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>
---
 fs/iomap.c            |    5 ++++-
 include/linux/iomap.h |    8 +++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

Patch

diff --git a/fs/iomap.c b/fs/iomap.c
index 7b295d5..e9b3f99 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -510,9 +510,12 @@  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 b2e30e5..3a56212 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 */
 };