.RB [ \-o
.IR offset ]
.B \-l
-.IR length
+.I length
.RB [ \-n ]
.I filename
.PP
.B fallocate \-x
.RB [ \-o
.IR offset ]
-.RB \-l
-.IR length
+.B \-l
+.I length
.I filename
.SH DESCRIPTION
.B fallocate
-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,
+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 zeroes.
+uninitialized, requiring no IO to the data blocks.
+This is much faster than creating a file by filling it with zeroes.
.PP
The exit code returned by
.B fallocate
is 0 on success and 1 on failure.
.SH OPTIONS
-The \fIlength\fR and \fIoffset\fR
+The
+.I length
+and
+.I offset
arguments may be followed by the multiplicative suffixes KiB (=1024),
-MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is
+MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB, and YiB (the "iB" is
optional, e.g., "K" has the same meaning as "KiB") or the suffixes
-KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
+KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB, and YB.
.PP
-The options \fB\-\-collapse\-range\fP, \fB\-\-dig\-holes\fP, \fB\-\-punch\-hole\fP and
-\fB\-\-zero\-range\fP are mutually exclusive.
+The options
+.BR \-\-collapse\-range ", " \-\-dig\-holes ", " \-\-punch\-hole ,
+and
+.B \-\-zero\-range
+are mutually exclusive.
.TP
-.BR \-c , " \-\-collapse\-range"
-Removes a byte range from a file, without leaving a hole. The byte range
-to be collapsed starts at \fIoffset\fP and continues
-for \fIlength\fR bytes. At the completion of the operation, the contents of
-the file starting at the location \fIoffset\fR+\fIlength\fR will be appended at the
-location \fIoffset\fR, and the file will be \fIlength\fR bytes smaller. The option
-\fB\-\-keep\-size\fR may not be specified for the collapse-range operation.
+.BR \-c ", " \-\-collapse\-range
+Removes a byte range from a file, without leaving a hole.
+The byte range to be collapsed starts at
+.I offset
+and continues for
+.I length
+bytes.
+At the completion of the operation,
+the contents of the file starting at the location
+.IR offset + length
+will be appended at the location
+.IR offset ,
+and the file will be
+.I length
+bytes smaller.
+The option
+.B \-\-keep\-size
+may not be specified for the collapse-range operation.
.sp
Available since Linux 3.15 for ext4 (only for extent-based files) and XFS.
.TP
-.BR \-d , " \-\-dig\-holes"
-Detect and dig holes. This makes the file sparse in-place, without using extra
-disk space. The minimum size of the hole depends on filesystem I/O block size
-(usually 4096 bytes). Also, when using this option, \fB\-\-keep\-size\fP is
-implied. If no range is specified by \fB\-\-offset\fP and \fB\-\-length\fP,
+.BR \-d ", " \-\-dig\-holes
+Detect and dig holes.
+This makes the file sparse in-place, without using extra disk space.
+The minimum size of the hole depends on filesystem I/O block size
+(usually 4096 bytes).
+Also, when using this option,
+.B \-\-keep\-size
+is implied. If no range is specified by
+.B \-\-offset
+and
+.BR \-\-length ,
then the entire file is analyzed for holes.
.sp
-You can think of this option as doing a "\fBcp --sparse\fP" and then renaming
-the destination file to the original, without the need for extra disk space.
+You can think of this option as doing a
+.RB """" "cp \-\-sparse" """"
+and then renaming the destination file to the original,
+without the need for extra disk space.
.sp
See \fB\-\-punch\-hole\fP for a list of supported filesystems.
.TP
-.BR \-i , " \-\-insert\-range"
-Insert a hole of \fIlength\fR bytes from \fIoffset\fR, shifting existing data.
+.BR \-i ", " \-\-insert\-range
+Insert a hole of
+.I length
+bytes from
+.IR offset ,
+shifting existing data.
.TP
-.BR \-l , " \-\-length " \fIlength
+.BR \-l ", " "\-\-length " \fIlength
Specifies the length of the range, in bytes.
.TP
-.BR \-n , " \-\-keep\-size"
+.BR \-n ", " \-\-keep\-size
Do not modify the apparent length of the file. This may effectively allocate
blocks past EOF, which can be removed with a truncate.
.TP
-.BR \-o , " \-\-offset " \fIoffset
+.BR \-o ", " "\-\-offset " \fIoffset
Specifies the beginning offset of the range, in bytes.
.TP
-.BR \-p , " \-\-punch\-hole"
+.BR \-p ", " \-\-punch\-hole
Deallocates space (i.e., creates a hole) in the byte range starting at
-\fIoffset\fP and continuing for \fIlength\fR bytes. Within the
-specified range, partial filesystem blocks are zeroed, and whole
-filesystem blocks are removed from the file. After a successful
-call, subsequent reads from this range will return zeroes. This option
-may not be specified at the same time as the \fB\-\-zero\-range\fP option.
-Also, when using this option, \fB\-\-keep\-size\fP is implied.
+.I offset
+and continuing for
+.I length
+bytes.
+Within the specified range, partial filesystem blocks are zeroed,
+and whole filesystem blocks are removed from the file.
+After a successful call,
+subsequent reads from this range will return zeroes.
+This option may not be specified at the same time as the
+.B \-\-zero\-range
+option.
+Also, when using this option,
+.B \-\-keep\-size
+is implied.
.sp
Supported for XFS (since Linux 2.6.38), ext4 (since Linux 3.0),
Btrfs (since Linux 3.7) and tmpfs (since Linux 3.5).
.TP
-.BR \-v , " \-\-verbose"
+.BR \-v ", " \-\-verbose
Enable verbose mode.
.TP
-.BR \-x , " \-\-posix"
-Enable POSIX operation mode. In that mode allocation operation always completes,
-but it may take longer time when fast allocation is not supported by the underlying filesystem.
+.BR \-x ", " \-\-posix
+Enable POSIX operation mode.
+In that mode allocation operation always completes,
+but it may take longer time when fast allocation is not supported by
+the underlying filesystem.
.TP
-.BR \-z , " \-\-zero\-range"
-Zeroes space in the byte range starting at \fIoffset\fP and
-continuing for \fIlength\fR bytes. Within the specified range, blocks are
-preallocated for the regions that span the holes in the file. After
-a successful call, subsequent reads from this range will return zeroes.
+.BR \-z ", " \-\-zero\-range
+Zeroes space in the byte range starting at
+.I offset
+and continuing for
+.I length
+bytes.
+Within the specified range, blocks are preallocated for the regions
+that span the holes in the file.
+After a successful call,
+subsequent reads from this range will return zeroes.
.sp
Zeroing is done within the filesystem preferably by converting the
range into unwritten extents. This approach means that the specified
.sp
Available since Linux 3.14 for ext4 (only for extent-based files) and XFS.
.TP
-.BR \-V , " \-\-version"
+.BR \-V ", " \-\-version
Display version information and exit.
.TP
-.BR \-h , " \-\-help"
+.BR \-h ", " \-\-help
Display help text and exit.
.SH AUTHORS
-.UR sandeen@redhat.com
+.MT sandeen@redhat.com
Eric Sandeen
-.UE
+.ME
.br
-.UR kzak@redhat.com
+.MT kzak@redhat.com
Karel Zak
-.UE
+.ME
.SH SEE ALSO
.BR truncate (1),
.BR fallocate (2),