touch-packages team mailing list archive

[Theodore Ts'o <tytso@xxxxxxx>]

The extent count calculation works correctly with the FIBMAP ioctl in
verbose (-v) mode, but without the verbose option, the calculation was
broken because we weren't properly updating the fm_ext data structures
in non-verbose mode.

Addresses-Launchpad-Bug: #1356496

Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
---
 misc/filefrag.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/misc/filefrag.c b/misc/filefrag.c
index d71bf43..c1a8684 100644
--- a/misc/filefrag.c
+++ b/misc/filefrag.c
@@ -329,16 +329,17 @@ static int filefrag_fibmap(int fd, int blk_shift, int *num_extents,
 			print_extent_info(&fm_ext, *num_extents - 1,
 					  (last_block + 1) * st->st_blksize,
 					  blk_shift, st);
-			fm_ext.fe_logical = logical;
-			fm_ext.fe_physical = block * st->st_blksize;
 			fm_ext.fe_length = 0;
 			(*num_extents)++;
 		} 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_length += st->st_blksize;
 		last_block = block;
 	}
-- 
2.0.0

-- 
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https://bugs.launchpad.net/bugs/1356496

Title:
  filefrag shows wrong number of extents

Status in “e2fsprogs” package in Ubuntu:
  Confirmed

Bug description:
  Package: E2fsprogs version 1.42.8

  In NTFS (and possibly other non-Linux filesystems), adding a '-v'
  switch to the filefrag command gives a different result from executing
  the command without the '-v' switch, for the same file.

  For example:

  $ sudo filefrag DSC_0466.mov
  DSC_0466.mov: 1 extent found

  $ sudo filefrag -v DSC_0466.mov
  Filesystem type is: 65735546
  File size of DSC_0466.mov is 38347615 (9363 blocks of 4096 bytes)
  Discontinuity: Block 1727 is at 53086291 (was 53063600)
  Discontinuity: Block 2547 is at 53168245 (was 53087111)
  Discontinuity: Block 4398 is at 53184685 (was 53170096)
  Discontinuity: Block 6193 is at 53276776 (was 53186480)
  Discontinuity: Block 6297 is at 53289023 (was 53276880)
  Discontinuity: Block 6422 is at 53344771 (was 53289148)
  Discontinuity: Block 7875 is at 53369116 (was 53346224)
  DSC_0466.mov: 8 extents found

  This has nothing to do with file system buffers, since this file has
  been on the disk for several months.

  This bug report says that the problem is fixed in E2fsprogs version 1.41: https://bugzilla.redhat.com/show_bug.cgi?id=927541
  but I think it has been fixed only for ext* file systems, since the problem exists with E2fsprogs version 1.42.8, with NTFS, but not with ext4. I think the problem also exists with FAT file systems, but I can't currently check this.

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