xfs_io: clarify the fsmap documentation

Explicitly declare that the 'start' and 'end' arguments to fsmap require
one of -d, -l, or -r to select the data, log, or realtime device, and fix
misspelled command name while we're at it.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

2 files changed, 7 insertions, 2 deletions

diff --git a/io/fsmap.c b/io/fsmap.c
index 9e70c7b48c..448fb53564 100644
--- a/io/fsmap.c
+++ b/io/fsmap.c
@@ -48,6 +48,8 @@ fsmap_help(void)
 " -n -- query n extents at a time.\n"
 " -m -- output machine-readable format.\n"
 " -v -- Verbose information, show AG and offsets.  Show flags legend on 2nd -v\n"
+"\n"
+"The optional start and end arguments require one of -d, -l, or -r to be set.\n"
 "\n"));
 }
 
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index 273b9c54c5..0fd9b95119 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -323,6 +323,9 @@ and
 .I end
 arguments can be used to constrain the output to a particular range of
 disk blocks.
+If these two options are specified, exactly one of
+.BR "-d" ", " "-l" ", or " "-r"
+must also be set.
 .RE
 .RS 1.0i
 .PD 0
@@ -372,12 +375,12 @@ for other filesystem metadata.
 .TP
 .BI \-n " num_extents"
 If this option is given,
-.B xfs_fsmap
+.B fsmap
 obtains the extent list of the file in groups of
 .I num_extents
 extents.
 In the absence of
-.BR \-n ", " xfs_fsmap
+.BR "-n" ", " "fsmap"
 queries the system for extents in groups of 131,072 records.
 .TP
 .B \-v