.\" -*- nroff -*-
.TH FALLOCATE 1 "September 2011" "util-linux" "User Commands"
.SH NAME
-fallocate \- preallocate space to a file
+fallocate \- preallocate or deallocate space to a file
.SH SYNOPSIS
.B fallocate
.RB [ \-n ]
.I filename
.SH DESCRIPTION
.B fallocate
-is used to preallocate blocks to a file. For filesystems which support the
-fallocate system call, this is done quickly by allocating blocks and marking
-them as uninitialized, requiring no IO to the data blocks. This is much faster
-than creating a file by filling it with zeros.
+is used to manipulate the allocated disk space for a file, either to deallocate
+or preallocate it. For filesystems which support the fallocate system call,
+preallocation is done quickly by allocating blocks and marking them as
+uninitialized, requiring no IO to the data blocks. This is much faster than
+creating a file by filling it with zeros.
.PP
As of the Linux Kernel v2.6.31, the fallocate system call is supported by the
btrfs, ext4, ocfs2, and xfs filesystems.
fputs(USAGE_OPTIONS, out);
fputs(_(" -n, --keep-size don't modify the length of the file\n"
" -p, --punch-hole punch holes in the file\n"
- " -o, --offset <num> offset of the allocation, in bytes\n"
- " -l, --length <num> length of the allocation, in bytes\n"), out);
+ " -o, --offset <num> offset of the (de)allocation, in bytes\n"
+ " -l, --length <num> length of the (de)allocation, in bytes\n"), out);
fputs(USAGE_SEPARATOR, out);
fputs(USAGE_HELP, out);
fputs(USAGE_VERSION, out);