[Ocfs2-devel] [PATCH 23/30] ocfs2: Handle missing export generic_segment_checks()

[Sunil Mushran]

Commit 0ceb331433e8aad9c5f441a965d7c681f8b9046f in mainline wraps
common segment checks in generic_segment_checks(). This patch allows
one to build ocfs2 with kernels having/not having this change.

Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>
---
 Config.make.in    |    1 +
 configure.in      |    5 +++++
 fs/ocfs2/Makefile |    4 ++++
 fs/ocfs2/file.c   |   40 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 50 insertions(+), 0 deletions(-)

diff --git a/Config.make.in b/Config.make.in
index 788c156..c1ca1d9 100644
--- a/Config.make.in
+++ b/Config.make.in
@@ -67,6 +67,7 @@ SU_MUTEX_DEFINED = @SU_MUTEX_DEFINED@
 STRUCT_SUBSYSTEM_DEFINED = @STRUCT_SUBSYSTEM_DEFINED@
 FALLOCATE_DEFINED = @FALLOCATE_DEFINED@
 SPLICE_HEADER = @SPLICE_HEADER@
+GENERIC_SEGMENT_CHECKS = @GENERIC_SEGMENT_CHECKS@
 
 OCFS_DEBUG = @OCFS_DEBUG@
 
diff --git a/configure.in b/configure.in
index 472e01a..a311d3f 100644
--- a/configure.in
+++ b/configure.in
@@ -262,6 +262,11 @@ OCFS2_CHECK_KERNEL([should_remove_suid() in fs.h], fs.h,
   SHOULD_REMOVE_SUID=yes, , [should_remove_suid()])
 AC_SUBST(SHOULD_REMOVE_SUID)
 
+GENERIC_SEGMENT_CHECKS=
+OCFS2_CHECK_KERNEL([generic_segment_checks() in fs.h], fs.h,
+  GENERIC_SEGMENT_CHECKS=yes, , [generic_segment_checks()])
+AC_SUBST(GENERIC_SEGMENT_CHECKS)
+
 # 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/fs/ocfs2/Makefile b/fs/ocfs2/Makefile
index a80a9fc..7434d6d 100644
--- a/fs/ocfs2/Makefile
+++ b/fs/ocfs2/Makefile
@@ -57,6 +57,10 @@ ifdef SHOULD_REMOVE_SUID
 EXTRA_CFLAGS += -DSHOULD_REMOVE_SUID
 endif
 
+ifdef GENERIC_SEGMENT_CHECKS
+EXTRA_CFLAGS += -DGENERIC_SEGMENT_CHECKS
+endif
+
 #
 # Since SUBDIRS means something to kbuild, define them safely.  Do not
 # include trailing slashes.
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index cee10ae..dd074af 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1809,6 +1809,46 @@ static long ocfs2_fallocate(struct inode *inode, int mode, loff_t offset,
 }
 #endif
 
+#ifndef GENERIC_SEGMENT_CHECKS
+/*
+ * Performs necessary checks before doing a write
+ * @iov:	io vector request
+ * @nr_segs:	number of segments in the iovec
+ * @count:	number of bytes to write
+ * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
+ *
+ * Adjust number of segments and amount of bytes to write (nr_segs should be
+ * properly initialized first). Returns appropriate error code that caller
+ * should return or zero in case that write should be allowed.
+ */
+int generic_segment_checks(const struct iovec *iov,
+			unsigned long *nr_segs, size_t *count, int access_flags)
+{
+	unsigned long   seg;
+	size_t cnt = 0;
+	for (seg = 0; seg < *nr_segs; seg++) {
+		const struct iovec *iv = &iov[seg];
+
+		/*
+		 * If any segment has a negative length, or the cumulative
+		 * length ever wraps negative then return -EINVAL.
+		 */
+		cnt += iv->iov_len;
+		if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
+			return -EINVAL;
+		if (access_ok(access_flags, iv->iov_base, iv->iov_len))
+			continue;
+		if (seg == 0)
+			return -EFAULT;
+		*nr_segs = seg;
+		cnt -= iv->iov_len;	/* This segment is no good */
+		break;
+	}
+	*count = cnt;
+	return 0;
+}
+#endif
+
 static int ocfs2_prepare_inode_for_write(struct dentry *dentry,
 					 loff_t *ppos,
 					 size_t count,
-- 
1.5.2.5