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authorGiuseppe Scrivano <gscrivano@gnu.org>2009-08-01 19:36:48 +0200
committerJim Meyering <meyering@redhat.com>2009-08-07 17:14:22 +0200
commita1d7469835371ded0ad8e3496bc5a5bebf94ccef (patch)
tree925945606aa919b7b48603117db6f8ca15e7b551
parentff159a605e5bc10fe871109f66cba5ee410c9138 (diff)
downloadcoreutils-a1d7469835371ded0ad8e3496bc5a5bebf94ccef.tar.xz
cp: accept the --reflink option
* NEWS: Mention it. * doc/coreutils.texi (cp invocation): Describe it. * src/copy.h (struct cp_options) [reflink]: New member. * src/copy.c (usage): Describe it. (copy_reg): If reflink is true try to clone the file. (main): Check for --reflink. (cp_option_init): Initialize the new member. * src/install.c (cp_option_init): Initialize the new member. * src/mv.c (cp_option_init): Likewise. * tests/cp/sparse: Add a new test case.
-rw-r--r--NEWS4
-rw-r--r--doc/coreutils.texi9
-rw-r--r--src/copy.c16
-rw-r--r--src/copy.h3
-rw-r--r--src/cp.c14
-rw-r--r--src/install.c1
-rw-r--r--src/mv.c1
-rwxr-xr-xtests/cp/sparse4
8 files changed, 46 insertions, 6 deletions
diff --git a/NEWS b/NEWS
index c61f6667b..6df0d65a6 100644
--- a/NEWS
+++ b/NEWS
@@ -41,6 +41,10 @@ GNU coreutils NEWS -*- outline -*-
chroot now accepts the options --userspec and --groups.
+ cp accepts a new option, --reflink: create a lightweight copy
+ using copy-on-write (COW). This is currently supported only on
+ btrfs file systems.
+
cp now preserves time stamps on symbolic links, when possible
cp, install, mv: take advantage of btrfs' O(1) copy-on-write feature
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 90a54b268..bb1d87a87 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -7543,6 +7543,15 @@ 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
+Perform a lightweight, copy-on-write (COW) copy.
+Copying with this option can succeed only on some relatively new 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.
+
@item --remove-destination
@opindex --remove-destination
Remove each existing destination file before attempting to open it
diff --git a/src/copy.c b/src/copy.c
index 24b5f6b46..bed90c459 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -624,13 +624,16 @@ copy_reg (char const *src_name, char const *dst_name,
goto close_src_and_dst_desc;
}
- /* If --sparse=auto is in effect, attempt a btrfs clone operation.
- If the operation is not supported or it fails then copy the file
- in the usual way. */
- bool copied = (x->sparse_mode == SPARSE_AUTO
- && clone_file (dest_desc, source_desc) == 0);
+ if (x->reflink)
+ {
+ if (clone_file (dest_desc, source_desc))
+ {
+ error (0, errno, _("failed to clone %s"), quote (dst_name));
+ return_val = false;
+ }
+ goto close_src_and_dst_desc;
+ }
- if (!copied)
{
typedef uintptr_t word;
off_t n_read_total = 0;
@@ -2232,6 +2235,7 @@ valid_options (const struct cp_options *co)
assert (VALID_BACKUP_TYPE (co->backup_type));
assert (VALID_SPARSE_MODE (co->sparse_mode));
assert (!(co->hard_link && co->symbolic_link));
+ assert (!(co->reflink && co->sparse_mode != SPARSE_AUTO));
return true;
}
diff --git a/src/copy.h b/src/copy.h
index 8e0b4080e..ddf4f4e2c 100644
--- a/src/copy.h
+++ b/src/copy.h
@@ -219,6 +219,9 @@ struct cp_options
such a symlink) and returns false. */
bool open_dangling_dest_symlink;
+ /* If true, attempt to clone the file instead of copying it. */
+ bool reflink;
+
/* This is a set of destination name/inode/dev triples. Each such triple
represents a file we have created corresponding to a source file name
that was specified on the command line. Use it to avoid clobbering
diff --git a/src/cp.c b/src/cp.c
index 878507616..c99aff311 100644
--- a/src/cp.c
+++ b/src/cp.c
@@ -76,6 +76,7 @@ enum
NO_PRESERVE_ATTRIBUTES_OPTION,
PARENTS_OPTION,
PRESERVE_ATTRIBUTES_OPTION,
+ REFLINK_OPTION,
SPARSE_OPTION,
STRIP_TRAILING_SLASHES_OPTION,
UNLINK_DEST_BEFORE_OPENING
@@ -121,6 +122,7 @@ static struct option const long_opts[] =
{"recursive", no_argument, NULL, 'R'},
{"remove-destination", no_argument, NULL, UNLINK_DEST_BEFORE_OPENING},
{"sparse", required_argument, NULL, SPARSE_OPTION},
+ {"reflink", no_argument, NULL, REFLINK_OPTION},
{"strip-trailing-slashes", no_argument, NULL, STRIP_TRAILING_SLASHES_OPTION},
{"suffix", required_argument, NULL, 'S'},
{"symbolic-link", no_argument, NULL, 's'},
@@ -190,6 +192,7 @@ Mandatory arguments to long options are mandatory for short options too.\n\
"), stdout);
fputs (_("\
-R, -r, --recursive copy directories recursively\n\
+ --reflink perform a lightweight (CoW/clone) copy\n\
--remove-destination remove each existing destination file before\n\
attempting to open it (contrast with --force)\n\
"), stdout);
@@ -752,6 +755,7 @@ cp_option_init (struct cp_options *x)
x->interactive = I_UNSPECIFIED;
x->move_mode = false;
x->one_file_system = false;
+ x->reflink = false;
x->preserve_ownership = false;
x->preserve_links = false;
@@ -916,6 +920,10 @@ main (int argc, char **argv)
sparse_type_string, sparse_type);
break;
+ case REFLINK_OPTION:
+ x.reflink = true;
+ break;
+
case 'a': /* Like -dR --preserve=all with reduced failure diagnostics. */
x.dereference = DEREF_NEVER;
x.preserve_links = true;
@@ -1076,6 +1084,12 @@ main (int argc, char **argv)
usage (EXIT_FAILURE);
}
+ if (x.reflink && x.sparse_mode != SPARSE_AUTO)
+ {
+ error (0, 0, _("--reflink can be used only with --sparse=auto"));
+ usage (EXIT_FAILURE);
+ }
+
if (backup_suffix_string)
simple_backup_suffix = xstrdup (backup_suffix_string);
diff --git a/src/install.c b/src/install.c
index fd8f71ef3..73b3981ef 100644
--- a/src/install.c
+++ b/src/install.c
@@ -269,6 +269,7 @@ cp_option_init (struct cp_options *x)
{
cp_options_default (x);
x->copy_as_regular = true;
+ x->reflink = false;
x->dereference = DEREF_ALWAYS;
x->unlink_dest_before_opening = true;
x->unlink_dest_after_failed_open = false;
diff --git a/src/mv.c b/src/mv.c
index 8b9b6a111..8d77380ac 100644
--- a/src/mv.c
+++ b/src/mv.c
@@ -105,6 +105,7 @@ cp_option_init (struct cp_options *x)
cp_options_default (x);
x->copy_as_regular = false; /* FIXME: maybe make this an option */
+ x->reflink = false;
x->dereference = DEREF_NEVER;
x->unlink_dest_before_opening = false;
x->unlink_dest_after_failed_open = false;
diff --git a/tests/cp/sparse b/tests/cp/sparse
index bd1a84f40..9683a9e33 100755
--- a/tests/cp/sparse
+++ b/tests/cp/sparse
@@ -38,4 +38,8 @@ cp --sparse=always sparse copy || fail=1
# Ensure that the copy has the same block count as the original.
test `stat --printf %b copy` -le `stat --printf %b sparse` || fail=1
+# Ensure that --sparse={always,never} with --reflink fail.
+cp --sparse=always --reflink sparse copy && fail=1
+cp --sparse=never --reflink sparse copy && fail=1
+
Exit $fail