.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
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
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.