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| author | Rodrigo Campos | 2014-01-26 16:06:50 +0100 |
|---|---|---|
| committer | Karel Zak | 2014-02-14 11:31:12 +0100 |
| commit | 24b2a479fd5ba138e9b836fa2115939eb3b59dfe (patch) | |
| tree | 59739edae84554396409a96a35b292e6ad274f10 /sys-utils/fallocate.1 | |
| parent | fallocate: Hide #ifdef tricks to call fallocate in a function (diff) | |
| download | kernel-qcow2-util-linux-24b2a479fd5ba138e9b836fa2115939eb3b59dfe.tar.gz kernel-qcow2-util-linux-24b2a479fd5ba138e9b836fa2115939eb3b59dfe.tar.xz kernel-qcow2-util-linux-24b2a479fd5ba138e9b836fa2115939eb3b59dfe.zip | |
fallocate: Add "--dig-holes" option
This option tries to detect chunk of '\0's and punch a hole, making the file
sparse in-place.
[kzak@redhat.com: - fix coding style, use xalloc.h and err.h]
Signed-off-by: Rodrigo Campos <rodrigo@sdfg.com.ar>
Signed-off-by: Karel Zak <kzak@redhat.com>
Diffstat (limited to 'sys-utils/fallocate.1')
| -rw-r--r-- | sys-utils/fallocate.1 | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/sys-utils/fallocate.1 b/sys-utils/fallocate.1 index efa42c1d2..04c426375 100644 --- a/sys-utils/fallocate.1 +++ b/sys-utils/fallocate.1 @@ -11,6 +11,12 @@ fallocate \- preallocate or deallocate space to a file .B \-l .IR length .I filename +.PP +.B fallocate +.RB \-d +.RB [ \-l +.IR length ] +.I filename .SH DESCRIPTION .B fallocate is used to manipulate the allocated disk space for a file, either to deallocate @@ -20,7 +26,8 @@ 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. +btrfs, ext4, ocfs2, and xfs filesystems. Support for options needed to run with +\fI\-\-punch-hole\fR or \fI\-\-detect-holes\fR was added in Linux 2.6.38. .PP The exit code returned by .B fallocate @@ -36,6 +43,16 @@ Do not modify the apparent length of the file. This may effectively allocate blocks past EOF, which can be removed with a truncate. .IP "\fB\-p, \-\-punch-hole\fP" Punch holes in the file, the range should not exceed the length of the file. +.IP "\fB\-d, \-\-dig-holes\fP" +Detect and dig holes of, at least, \fIlength\fR size. If \fIlength\fR is not +specified, it defaults to 32k. Makes the file sparse in-place, without using +extra disk space. You can think of this as doing a "\fBcp --sparse\fP" and +renaming the dest file as the original, without the need for extra disk space. +.PP +.IP +Note that too small values for \fIlength\fR might be ignored. And too big values +might use lot of RAM and not detect many holes. Also, when using this option, +\fI\-\-keep-size\fP is implied. .IP "\fB\-o, \-\-offset\fP \fIoffset\fP Specifies the beginning offset of the allocation, in bytes. .IP "\fB\-l, \-\-length\fP \fIlength\fP |