[Ocfs2-devel] [PATCH 10/30] ocfs2: Add helper drop_nlink

[Sunil Mushran]

Commit 9a53c3a783c2fa9b969628e65695c11c3e51e673 in mainline added
helper drop_nlink(). This patch allows one to build ocfs2 with kernels
having/not having that change.

Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>
---
 Makefile                         |    3 ++-
 configure.in                     |    5 +++++
 kapi-compat/include/drop_nlink.h |   22 ++++++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletions(-)
 create mode 100644 kapi-compat/include/drop_nlink.h

diff --git a/Makefile b/Makefile
index 1595b90..2a97e00 100644
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,8 @@ KAPI_COMPAT_FILES = \
 	kapi-compat/include/highmem.h \
 	kapi-compat/include/fpath.h \
 	kapi-compat/include/kmod.h \
-	kapi-compat/include/inc_nlink.h
+	kapi-compat/include/inc_nlink.h \
+	kapi-compat/include/drop_nlink.h
 
 PATCH_FILES =
 
diff --git a/configure.in b/configure.in
index 554a0a4..81041fb 100644
--- a/configure.in
+++ b/configure.in
@@ -193,6 +193,11 @@ OCFS2_CHECK_KERNEL([inc_nlink() in fs.h], fs.h,
   , inc_nlink_compat_header="inc_nlink.h", [^static inline void inc_nlink(])
 KAPI_COMPAT_HEADERS="$KAPI_COMPAT_HEADERS $inc_nlink_compat_header"
 
+drop_nlink_compat_header=""
+OCFS2_CHECK_KERNEL([drop_nlink() in fs.h], fs.h,
+  , drop_nlink_compat_header="drop_nlink.h", [^static inline void drop_nlink(])
+KAPI_COMPAT_HEADERS="$KAPI_COMPAT_HEADERS $drop_nlink_compat_header"
+
 # using -include has two advantages:
 #  the source doesn't need to know to include compat headers
 #  the compat header file names don't go through the search path
diff --git a/kapi-compat/include/drop_nlink.h b/kapi-compat/include/drop_nlink.h
new file mode 100644
index 0000000..d54973b
--- /dev/null
+++ b/kapi-compat/include/drop_nlink.h
@@ -0,0 +1,22 @@
+#ifndef KAPI_DROP_NLINK_H
+#define KAPI_DROP_NLINK_H
+
+#include <linux/fs.h>
+
+/*
+ * drop_nlink - directly drop an inode's link count
+ * @inode: inode
+ *
+ * This is a low-level filesystem helper to replace any
+ * direct filesystem manipulation of i_nlink.  In cases
+ * where we are attempting to track writes to the
+ * filesystem, a decrement to zero means an imminent
+ * write when the file is truncated and actually unlinked
+ * on the filesystem.
+ */
+static inline void drop_nlink(struct inode *inode)
+{
+	inode->i_nlink--;
+}
+
+#endif
-- 
1.5.2.5