[PATCH 6/6] fiemap: Fix semantics of max_extents (-n arguments)

[Nikolay Borisov <nborisov@suse.com>]

Currently the semantics of the -n argument are a bit idiosyncratic. We want the
argument to be the limit of extents that are going to be output by the tool. This
is clearly broken now as evident from the following example on a fragmented file:

xfs_io -c "fiemap -v -n 5" test-dir/fragmented-file
test-dir/fragmented-file:
 EXT: FILE-OFFSET      BLOCK-RANGE          TOTAL FLAGS
   0: [0..15]:         hole                    16
   1: [16..23]:        897847296..897847303     8   0x0
   2: [24..31]:        hole                     8
   3: [32..39]:        897851392..897851399     8   0x0

So we want at most 5 extents printed, yet we get 4. So we always print n - 1
extents.

With this modification the output looks like:

xfs_io -c "fiemap -v -n 5" test-dir/fragmented-file
test-dir/fragmented-file:
 EXT: FILE-OFFSET      BLOCK-RANGE          TOTAL FLAGS
   0: [0..15]:         hole                    16
   1: [16..23]:        897847296..897847303     8   0x0
   2: [24..31]:        hole                     8
   3: [32..39]:        897851392..897851399     8   0x0
   4: [40..47]:        hole                     8

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 io/fiemap.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/io/fiemap.c b/io/fiemap.c
index 44a64870d711..7b275275465d 100644
--- a/io/fiemap.c
+++ b/io/fiemap.c
@@ -122,7 +122,7 @@ print_verbose(
 		cur_extent++;
 	}
 
-	if ((cur_extent + 1) == max_extents)
+	if (cur_extent == max_extents)
 		return 1;
 
 	snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:", lstart,
@@ -157,7 +157,7 @@ print_plain(
 		cur_extent++;
 	}
 
-	if ((cur_extent + 1) == max_extents)
+	if (cur_extent == max_extents)
 		return 1;
 
 	printf("\t%d: [%llu..%llu]: %llu..%llu", cur_extent,
@@ -264,7 +264,7 @@ fiemap_f(
 
 	printf("%s:\n", file->name);
 
-	while (!last && ((cur_extent + 1) != max_extents)) {
+	while (!last && (cur_extent != max_extents)) {
 
 		memset(fiemap, 0, map_size);
 		fiemap->fm_flags = fiemap_flags;
@@ -314,12 +314,12 @@ fiemap_f(
 				break;
 			}
 
-			if ((cur_extent + 1) == max_extents)
+			if (cur_extent == max_extents)
 				break;
 		}
 	}
 
-	if ((cur_extent + 1) == max_extents)
+	if (cur_extent  == max_extents)
 		goto out;
 
 	memset(&st, 0, sizeof(st));
-- 
2.7.4