filefrag: fix broken extent emulation and uninitialized variables

This started with the fm_ext being uninitialized, but upon closer
analysis I discovered that forcing extent emulation in FIBMAP mode
was reporting an extent for every block in the file.  Fix both
problems.

The Coverity bug was 1297512.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/misc/filefrag.c b/misc/filefrag.c
index c1a8684..3b104c6 100644 (file)
--- a/misc/filefrag.c
+++ b/misc/filefrag.c
@@ -287,8 +287,8 @@ static int filefrag_fibmap(int fd, int blk_shift, int *num_extents,
        const long              bpib = st->st_blksize / 4;
        int                     count;
 
+       memset(&fm_ext, 0, sizeof(fm_ext));
        if (force_extent) {
-               memset(&fm_ext, 0, sizeof(fm_ext));
                fm_ext.fe_flags = FIEMAP_EXTENT_MERGED;
        }
 
@@ -331,15 +331,17 @@ static int filefrag_fibmap(int fd, int blk_shift, int *num_extents,
                                          blk_shift, st);
                        fm_ext.fe_length = 0;
                        (*num_extents)++;
+                       fm_ext.fe_logical = logical;
+                       fm_ext.fe_physical = block * st->st_blksize;
                } else if (last_block && (block != last_block + 1)) {
                        if (verbose)
                                printf("Discontinuity: Block %ld is at %lu (was "
                                       "%lu)\n", i, block, last_block + 1);
                        fm_ext.fe_length = 0;
                        (*num_extents)++;
+                       fm_ext.fe_logical = logical;
+                       fm_ext.fe_physical = block * st->st_blksize;
                }
-               fm_ext.fe_logical = logical;
-               fm_ext.fe_physical = block * st->st_blksize;
                fm_ext.fe_length += st->st_blksize;
                last_block = block;
        }