From: Pádraig Brady
Date: Wed, 30 Mar 2011 21:50:05 +0000 (+0100)
Subject: copy: with fiemap copy, only sync when needed
X-Git-Tag: v8.11~31
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f69876e558782eb770955aa0b1344a5a8262548b;p=platform%2Fupstream%2Fcoreutils.git
copy: with fiemap copy, only sync when needed
* src/extent-scan.h (struct extent_scan): Add the fm_flags member to
pass to the fiemap scan.
* src/extent-scan.c (extent_need_sync): A new function used to
detect Linux kernels before 2.6.38.
(extent_scan_init): Add FIEMAP_FLAG_SYNC when needed.
* tests/cp/sparse-fiemap: Adjust comment.
* NEWS: Mention the change in behavior.
Indirectly suggested by Mike Frysinger
---
diff --git a/NEWS b/NEWS
index e93f013..6d66355 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,10 @@ GNU coreutils NEWS -*- outline -*-
** Changes in behavior
+ cp now avoids syncing files when possible, when doing a FIEMAP copy.
+ The sync in only needed on Linux kernels before 2.6.38.
+ [The sync was introduced in coreutils-8.10]
+
df now aligns columns consistently, and no longer wraps entries
with longer device identifiers, over two lines.
diff --git a/src/extent-scan.c b/src/extent-scan.c
index b9520b7..f10d8e0 100644
--- a/src/extent-scan.c
+++ b/src/extent-scan.c
@@ -20,15 +20,46 @@
#include
#include
#include
+#include
#include
#include "system.h"
#include "extent-scan.h"
+#include "xstrtol.h"
#ifndef HAVE_FIEMAP
# include "fiemap.h"
#endif
+/* Work around Linux kernel issues on BTRFS and EXT4 before 2.6.38.
+ FIXME: remove in 2013, or whenever we're pretty confident
+ that the offending, unpatched kernels are no longer in use. */
+static bool
+extent_need_sync (void)
+{
+ static int need_sync = -1;
+
+ if (need_sync == -1)
+ {
+ struct utsname name;
+ need_sync = 0; /* No workaround by default. */
+
+#ifdef __linux__
+ if (uname (&name) != -1 && strncmp (name.release, "2.6.", 4) == 0)
+ {
+ unsigned long val;
+ if (xstrtoul (name.release + 4, NULL, 10, &val, NULL) == LONGINT_OK)
+ {
+ if (val < 38)
+ need_sync = 1;
+ }
+ }
+#endif
+ }
+
+ return need_sync;
+}
+
/* Allocate space for struct extent_scan, initialize the entries if
necessary and return it as the input argument of extent_scan_read(). */
extern void
@@ -39,6 +70,7 @@ extent_scan_init (int src_fd, struct extent_scan *scan)
scan->scan_start = 0;
scan->initial_scan_failed = false;
scan->hit_final_extent = false;
+ scan->fm_flags = extent_need_sync () ? FIEMAP_FLAG_SYNC : 0;
}
#ifdef __linux__
@@ -62,7 +94,7 @@ extent_scan_read (struct extent_scan *scan)
memset (&fiemap_buf, 0, sizeof fiemap_buf);
fiemap->fm_start = scan->scan_start;
- fiemap->fm_flags = FIEMAP_FLAG_SYNC;
+ fiemap->fm_flags = scan->fm_flags;
fiemap->fm_extent_count = count;
fiemap->fm_length = FIEMAP_MAX_OFFSET - scan->scan_start;
diff --git a/src/extent-scan.h b/src/extent-scan.h
index 4724b25..8728515 100644
--- a/src/extent-scan.h
+++ b/src/extent-scan.h
@@ -41,6 +41,9 @@ struct extent_scan
/* Next scan start offset. */
off_t scan_start;
+ /* Flags to use for scan. */
+ uint32_t fm_flags;
+
/* How many extent info returned for a scan. */
uint32_t ei_count;
diff --git a/tests/cp/sparse-fiemap b/tests/cp/sparse-fiemap
index 73448ec..bac2890 100755
--- a/tests/cp/sparse-fiemap
+++ b/tests/cp/sparse-fiemap
@@ -69,8 +69,8 @@ for i in $(seq 1 2 21); do
-e 'for (1..'$j') { sysseek (*F, $n, 1)' \
-e '&& syswrite (*F, chr($_)x$n) or die "$!"}' > j1 || fail=1
- # Note there is an implicit sync performed by cp to
- # work around bugs in EXT4 and BTRFS before Linux 2.6.38
+ # Note there is an implicit sync performed by cp on Linux kernels
+ # before 2.6.38 to work around bugs in EXT4 and BTRFS.
# Note also the -s parameter to the filefrag commands below
# for the same reasons.
cp --sparse=always j1 j2 || fail=1