diff options
| author | Jim Meyering <meyering@redhat.com> | 2009-08-04 19:54:58 +0200 |
|---|---|---|
| committer | Jim Meyering <meyering@redhat.com> | 2009-08-06 09:41:50 +0200 |
| commit | 5929322ccb1f9d27c1b07b746d37419d17a7cbf6 (patch) | |
| tree | 685ca3efe05ce619b33392ea499ad87c1c7a620c /doc | |
| parent | 365fb90eaae52c92d6af8e87769e72b872492f4a (diff) | |
| download | coreutils-5929322ccb1f9d27c1b07b746d37419d17a7cbf6.tar.xz | |
dd: work around buffer length restrictions with oflag=direct (O_DIRECT)
dd oflag=direct would fail to copy a file with size that is
not a multiple of 512 (destination file system specific)
* NEWS (Bug fixes): Mention it.
* src/dd.c (iwrite): Turn off O_DIRECT for any
smaller-than-obs-sized write. Don't bother to restore it.
* tests/dd/direct: New test for the above.
* tests/Makefile.am (TESTS): Add dd/direct.
* doc/coreutils.texi (dd invocation): Mention oflag=direct
buffer size restriction.
Details in http://thread.gmane.org/gmane.comp.gnu.coreutils.bugs/17586
Reported by Eric Sandeen.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/coreutils.texi | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/doc/coreutils.texi b/doc/coreutils.texi index acec76e4c..90a54b268 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -7861,6 +7861,10 @@ same time. @opindex direct @cindex direct I/O Use direct I/O for data, avoiding the buffer cache. +Note that the kernel may impose restrictions on read or write buffer sizes. +For example, with an ext4 destination file system and a linux-based kernel, +using @samp{oflag=direct} will cause writes to fail with @code{EINVAL} if the +output buffer size is not a multiple of 512. @item directory @opindex directory |