Add clarifications to the e4defrag and resize2fs man pages

Addresses-Debian-Bug: #761144
Addresses-Debian-Bug: #770750

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

by 1 commit.

Author: tytso

misc/e4defrag.8.in

@@ -66,6 +66,16 @@ is a device or a mount point,
 .B e4defrag
 doesn't defragment files in mount point of other device.
 .PP
+It safe to run e4defrag on a file while it is actively in use by another
+application.  Since the contents of file blocks are copied using the
+page cache, this can result in a performance slowdown to both e4defrag
+and the application due to contention over the system's memory and disk
+bandwidth.
+.PP
+If the file system's free space is fragmented, or if there is
+insufficient free space available, e4defrag may not be able
+to improve the file's fragmentation.
+.PP
 Non-privileged users can execute
 .B e4defrag
 to their own file, but the score is not printed if

resize/resize2fs.8.in

@@ -133,7 +133,8 @@ really useful for doing
 time trials.
 .TP
 .B \-M
-Shrink the filesystem to the minimum size.
+Shrink the file system to minimize its size as much as possible,
+given the files stored in the file system.
 .TP
 .B \-p
 Prints out a percentage completion bars for each
@@ -142,7 +143,11 @@ operation during an offline resize, so that the user can keep track
 of what the program is doing.
 .TP
 .B \-P
-Print the minimum size of the filesystem and exit.
+Print an extimate of the number of file system blocks in the file system
+if it is shrunk using
+.BR resize2fs 's
+.B \-M
+option and then exit.
 .TP
 .B \-s
 Turns off the 64bit feature and frees blocks that are no longer in use.