[PATCH v2] Makefile / racy-git.txt: clarify USE_NSEC prerequisites
Signed-off-by: Karsten Blees <blees@dcon.de>
---
...just changed wording as you suggested.
Documentation/technical/racy-git.txt | 8 ++++++--
Makefile | 9 +++++----
2 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/Documentation/technical/racy-git.txt b/Documentation/technical/racy-git.txt
index 242a044..4a8be4d 100644
--- a/Documentation/technical/racy-git.txt
+++ b/Documentation/technical/racy-git.txt
@@ -41,13 +41,17 @@ With a `USE_STDEV` compile-time option, `st_dev` is also
compared, but this is not enabled by default because this member
is not stable on network filesystems. With `USE_NSEC`
compile-time option, `st_mtim.tv_nsec` and `st_ctim.tv_nsec`
-members are also compared, but this is not enabled by default
+members are also compared. On Linux, this is not enabled by default
because in-core timestamps can have finer granularity than
on-disk timestamps, resulting in meaningless changes when an
inode is evicted from the inode cache. See commit 8ce13b0
of git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
([PATCH] Sync in core time granularity with filesystems,
-2005-01-04).
+2005-01-04). This patch is included in kernel 2.6.11 and newer, but
+only fixes the issue for file systems with exactly 1 ns or 1 s
+resolution. Other file systems are still broken in current Linux
+kernels (e.g. CEPH, CIFS, NTFS, UDF), see
+https://lkml.org/lkml/2015/6/9/714
Racy Git
--------
diff --git a/Makefile b/Makefile
index 54ec511..46d181a 100644
--- a/Makefile
+++ b/Makefile
@@ -217,10 +217,11 @@ all::
# as the compiler can crash (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49299)
#
# Define USE_NSEC below if you want git to care about sub-second file mtimes
-# and ctimes. Note that you need recent glibc (at least 2.2.4) for this, and
-# it will BREAK YOUR LOCAL DIFFS! show-diff and anything using it will likely
-# randomly break unless your underlying filesystem supports those sub-second
-# times (my ext3 doesn't).
+# and ctimes. Note that you need recent glibc (at least 2.2.4) for this. On
+# Linux, kernel 2.6.11 or newer is required for reliable sub-second file times
+# on file systems with exactly 1 ns or 1 s resolution. If you intend to use Git
+# on other file systems (e.g. CEPH, CIFS, NTFS, UDF), don't enable USE_NSEC. See
+# Documentation/technical/racy-git.txt for details.
#
# Define USE_ST_TIMESPEC if your "struct stat" uses "st_ctimespec" instead of
# "st_ctim"
--
2.4.3.windows.1.1.g87477f9
Karsten Blees <karsten.blees@gmail.com>