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| author | Pádraig Brady <P@draigBrady.com> | 2009-08-26 00:32:43 +0100 |
|---|---|---|
| committer | Pádraig Brady <P@draigBrady.com> | 2009-08-29 00:24:49 +0100 |
| commit | 72f98388c36676e5c9ba6a72df5693c207862204 (patch) | |
| tree | f0f54bfdb3a16d87cd180226021de9a7570bd9e7 /doc | |
| parent | f296cf4052c5299c7e6b1c14dcffa4785982a8ce (diff) | |
| download | coreutils-72f98388c36676e5c9ba6a72df5693c207862204.tar.xz | |
cp --reflink: add an "auto" parameter to fall back to a normal copy
* doc/coreutils.texi (cp invocation): Document the new
"auto" and "always" options to --reflink.
* src/copy.c (copy_reg): Fall back to a standard copy
when reflink() is not supported and --reflink=auto specified.
* src/copy.h [struct cp_options] (reflink): Change type s/bool/enum/.
* src/cp.c (usage): Describe the --reflink={always,auto} options
and expand a little on what --reflink does.
(main): parse the new parameters to --reflink and allow all
--sparse options with --reflink=auto.
* src/install.c (cp_option_init): Init the enum instead of bool.
* src/mv.c (cp_option_init): Likewise.
* tests/cp/reflink-auto: A new test for falling back to normal copy.
* tests/Makefile.am: Reference the new test.
* NEWS: Mention the new feature.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/coreutils.texi | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 8e1b73d63..f4be2c2f0 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -7543,15 +7543,31 @@ Also, it is not portable to use @option{-R} to copy symbolic links unless you also specify @option{-P}, as @acronym{POSIX} allows implementations that dereference symbolic links by default. -@item --reflink -@opindex --reflink +@item --reflink[=@var{when}] +@opindex --reflink[=@var{when}] +@cindex COW +@cindex clone +@cindex copy on write Perform a lightweight, copy-on-write (COW) copy. -Copying with this option can succeed only on some relatively new file systems. +Copying with this option can succeed only on some file systems. Once it has succeeded, beware that the source and destination files share the same disk data blocks as long as they remain unmodified. Thus, if a disk I/O error affects data blocks of one of the files, the other suffers the exact same fate. +The @var{when} value can be one of the following: + +@table @samp +@item always +The default behavior: if the copy-on-write operation is not supported +then report the failure for each file and exit with a failure status. + +@item auto +If the copy-on-write operation is not supported then fall back +to the standard copy behaviour. +@end table + + @item --remove-destination @opindex --remove-destination Remove each existing destination file before attempting to open it |