[PATCH v6 06/15] ovl: Add helper ovl_already_copied_up()

[Vivek Goyal <vgoyal@redhat.com>]

There are couple of places where we need to know if file is already copied
up (in lockless manner). Right now its open coded and there are only
two conditions to check. Soon this patch series will introduce another
condition to check and Amir wants to introduce one more. So introduce
a helper instead to check this so that code is easier to read.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 fs/overlayfs/copy_up.c   | 16 +---------------
 fs/overlayfs/inode.c     |  3 +--
 fs/overlayfs/overlayfs.h |  1 +
 fs/overlayfs/util.c      | 24 +++++++++++++++++++++++-
 4 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 6bb6b1723564..23122bdf0b14 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -651,21 +651,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
 		struct dentry *next;
 		struct dentry *parent;
 
-		/*
-		 * Check if copy-up has happened as well as for upper alias (in
-		 * case of hard links) is there.
-		 *
-		 * Both checks are lockless:
-		 *  - false negatives: will recheck under oi->lock
-		 *  - false positives:
-		 *    + ovl_dentry_upper() uses memory barriers to ensure the
-		 *      upper dentry is up-to-date
-		 *    + ovl_dentry_has_upper_alias() relies on locking of
-		 *      upper parent i_rwsem to prevent reordering copy-up
-		 *      with rename.
-		 */
-		if (ovl_dentry_upper(dentry) &&
-		    ovl_dentry_has_upper_alias(dentry))
+		if (ovl_already_copied_up(dentry))
 			break;
 
 		next = dget(dentry);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 00b6b294272a..537dc25f84c6 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -343,8 +343,7 @@ struct posix_acl *ovl_get_acl(struct inode *inode, int type)
 
 static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
 {
-	if (ovl_dentry_upper(dentry) &&
-	    ovl_dentry_has_upper_alias(dentry))
+	if (ovl_already_copied_up(dentry))
 		return false;
 
 	if (special_file(d_inode(dentry)->i_mode))
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 9e5aaa4a5db2..a6fdc2f0da6d 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -228,6 +228,7 @@ bool ovl_is_whiteout(struct dentry *dentry);
 struct file *ovl_path_open(struct path *path, int flags);
 int ovl_copy_up_start(struct dentry *dentry);
 void ovl_copy_up_end(struct dentry *dentry);
+bool ovl_already_copied_up(struct dentry *dentry);
 bool ovl_check_origin_xattr(struct dentry *dentry);
 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index c5b62546c613..f4e3e011a097 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -342,7 +342,7 @@ int ovl_copy_up_start(struct dentry *dentry)
 	int err;
 
 	err = mutex_lock_interruptible(&oi->lock);
-	if (!err && ovl_dentry_has_upper_alias(dentry)) {
+	if (!err && ovl_already_copied_up(dentry)) {
 		err = 1; /* Already copied up */
 		mutex_unlock(&oi->lock);
 	}
@@ -368,6 +368,28 @@ bool ovl_check_origin_xattr(struct dentry *dentry)
 	return false;
 }
 
+bool ovl_already_copied_up(struct dentry *dentry)
+{
+	/*
+	 * Check if copy-up has happened as well as for upper alias (in
+	 * case of hard links) is there.
+	 *
+	 * Both checks are lockless:
+	 *  - false negatives: will recheck under oi->lock
+	 *  - false positives:
+	 *    + ovl_dentry_upper() uses memory barriers to ensure the
+	 *      upper dentry is up-to-date
+	 *    + ovl_dentry_has_upper_alias() relies on locking of
+	 *      upper parent i_rwsem to prevent reordering copy-up
+	 *      with rename.
+	 */
+	if (ovl_dentry_upper(dentry) &&
+	    ovl_dentry_has_upper_alias(dentry))
+		return true;
+
+	return false;
+}
+
 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
 {
 	int res;
-- 
2.13.6