iomap: add IOMAP_REPORT

This allows the file system to tell a FIEMAP from a read operation, and thus
avoids the need to report flags that aren't actually used in the read path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

2 files changed, 12 insertions, 7 deletions

diff --git a/fs/iomap.c b/fs/iomap.c
index 013d1d36fbbf..a92204012e2d 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -561,7 +561,7 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
         }
 
         while (len > 0) {
-                ret = iomap_apply(inode, start, len, 0, ops, &ctx,
+                ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
                                 iomap_fiemap_actor);
                 /* inode with no (attribute) mapping will give ENOENT */
                 if (ret == -ENOENT)
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index e63e288dee83..7892f55a1866 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -19,11 +19,15 @@ struct vm_fault;
 #define IOMAP_UNWRITTEN 0x04    /* blocks allocated @blkno in unwritten state */
 
 /*
- * Flags for iomap mappings:
+ * Flags for all iomap mappings:
  */
-#define IOMAP_F_MERGED  0x01    /* contains multiple blocks/extents */
-#define IOMAP_F_SHARED  0x02    /* block shared with another file */
-#define IOMAP_F_NEW     0x04    /* blocks have been newly allocated */
+#define IOMAP_F_NEW     0x01    /* blocks have been newly allocated */
+
+/*
+ * Flags that only need to be reported for IOMAP_REPORT requests:
+ */
+#define IOMAP_F_MERGED  0x10    /* contains multiple blocks/extents */
+#define IOMAP_F_SHARED  0x20    /* block shared with another file */
 
 /*
  * Magic value for blkno:
@@ -42,8 +46,9 @@ struct iomap {
 /*
  * Flags for iomap_begin / iomap_end.  No flag implies a read.
  */
-#define IOMAP_WRITE             (1 << 0)
-#define IOMAP_ZERO              (1 << 1)
+#define IOMAP_WRITE             (1 << 0) /* writing, must allocate blocks */
+#define IOMAP_ZERO              (1 << 1) /* zeroing operation, may skip holes */
+#define IOMAP_REPORT            (1 << 2) /* report extent status, e.g. FIEMAP */
 
 struct iomap_ops {
         /*