It seems that accessing NTFS partitions with ufsd (at least on my EeePC)
has an unnerving bug: if you link() a file and unlink() it right away,
the target of the link() will have the correct size, but consist of
NULs.
It seems as if the calls are simply not serialized correctly, as
single-stepping through the function move_temp_to_file() works
flawlessly.
On Linux, this issue can be fixed by setting core.fsyncobjects to true
(thanks Linus), but the same is not true on Windows.
So, force the use of rename() instead of the link() && unlink()
incantation on Windows, and for good measure, add a
core.unreliableHardlinks option to optionally force it on other
platforms, too.
This fixes msysGit issues 222 and 229.
It was substantially improved by the help of Junio.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
[TENTATIVE] Acked-by: Johannes Sixt <j6t@xxxxxxxx>
---
Hannes, is it okay to remove the [TENTATIVE]?
Junio, do you want me to remove the config variable?
Documentation/config.txt | 5 +++++
Makefile | 8 ++++++++
cache.h | 2 ++
config.c | 5 +++++
environment.c | 4 ++++
sha1_file.c | 3 +++
6 files changed, 27 insertions(+), 0 deletions(-)
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 3188569..d31adb6 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -429,6 +429,11 @@ relatively high IO latencies. With this set to 'true', git will do the
index comparison to the filesystem data in parallel, allowing
overlapping IO's.
+core.unreliableHardlinks::
+ Some filesystem drivers cannot properly handle hardlinking a file
+ and deleting the source right away. In such a case, you need to
+ set this config variable to 'true'.
+
alias.*::
Command aliases for the linkgit:git[1] command wrapper - e.g.
after defining "alias.last = cat-file commit HEAD", the invocation
diff --git a/Makefile b/Makefile
index 6f602c7..5c8e83a 100644
--- a/Makefile
+++ b/Makefile
@@ -171,6 +171,10 @@ all::
# Define UNRELIABLE_FSTAT if your system's fstat does not return the same
# information on a not yet closed file that lstat would return for the same
# file after it was closed.
+#
+# Define UNRELIABLE_HARDLINKS if your operating systems has problems when
+# hardlinking a file to another name and unlinking the original file right
+# away (some NTFS drivers seem to zero the contents in that scenario).
GIT-VERSION-FILE: .FORCE-GIT-VERSION-FILE
@$(SHELL_PATH) ./GIT-VERSION-GEN
@@ -835,6 +839,7 @@ ifneq (,$(findstring MINGW,$(uname_S)))
NO_NSEC = YesPlease
USE_WIN32_MMAP = YesPlease
UNRELIABLE_FSTAT = UnfortunatelyYes
+ UNRELIABLE_HARDLINKS = UnfortunatelySometimes
COMPAT_CFLAGS += -D__USE_MINGW_ACCESS -DNOGDI -Icompat -Icompat/regex -Icompat/fnmatch
COMPAT_CFLAGS += -DSNPRINTF_SIZE_CORR=1
COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\"
@@ -1018,6 +1023,9 @@ else
COMPAT_OBJS += compat/win32mmap.o
endif
endif
+ifdef UNRELIABLE_HARDLINKS
+ COMPAT_CFLAGS += -DUNRELIABLE_HARDLINKS=1
+endif
ifdef NO_PREAD
COMPAT_CFLAGS += -DNO_PREAD
COMPAT_OBJS += compat/pread.o
diff --git a/cache.h b/cache.h
index ab1294d..ff9e145 100644
--- a/cache.h
+++ b/cache.h
@@ -554,6 +554,8 @@ extern enum branch_track git_branch_track;
extern enum rebase_setup_type autorebase;
extern enum push_default_type push_default;
+extern int unreliable_hardlinks;
+
#define GIT_REPO_VERSION 0
extern int repository_format_version;
extern int check_repository_format(void);
diff --git a/config.c b/config.c
index 8c1ae59..1750cfb 100644
--- a/config.c
+++ b/config.c
@@ -495,6 +495,11 @@ static int git_default_core_config(const char *var, const char *value)
return 0;
}
+ if (!strcmp(var, "core.unreliablehardlinks")) {
+ unreliable_hardlinks = git_config_bool(var, value);
+ return 0;
+ }
+
/* Add other config variables here and to Documentation/config.txt. */
return 0;
}
diff --git a/environment.c b/environment.c
index 4696885..10578d2 100644
--- a/environment.c
+++ b/environment.c
@@ -43,6 +43,10 @@ unsigned whitespace_rule_cfg = WS_DEFAULT_RULE;
enum branch_track git_branch_track = BRANCH_TRACK_REMOTE;
enum rebase_setup_type autorebase = AUTOREBASE_NEVER;
enum push_default_type push_default = PUSH_DEFAULT_UNSPECIFIED;
+#ifndef UNRELIABLE_HARDLINKS
+#define UNRELIABLE_HARDLINKS 0
+#endif
+int unreliable_hardlinks = UNRELIABLE_HARDLINKS;
/* Parallel index stat data preload? */
int core_preload_index = 0;
diff --git a/sha1_file.c b/sha1_file.c
index 8fe135d..0d289f4 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2225,6 +2225,8 @@ int move_temp_to_file(const char *tmpfile, const char *filename)
{
int ret = 0;
+ if (unreliable_hardlinks)
+ goto try_rename;
if (link(tmpfile, filename))
ret = errno;
@@ -2240,6 +2242,7 @@ int move_temp_to_file(const char *tmpfile, const char *filename)
* left to unlink.
*/
if (ret && ret != EEXIST) {
+try_rename:
if (!rename(tmpfile, filename))
goto out;
ret = errno;
--
1.6.2.1.613.g25746
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