kernel: implement RENAME_EXCHANGE support for jffs2 - overlayfs requires it

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 45580

target/linux/generic/patches-3.18/111-jffs2-add-RENAME_EXCHANGE-support.patch

+From: Felix Fietkau <nbd@openwrt.org>
+Date: Sat, 25 Apr 2015 12:41:32 +0200
+Subject: [PATCH] jffs2: add RENAME_EXCHANGE support
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+---
+
+--- a/fs/jffs2/dir.c
++++ b/fs/jffs2/dir.c
+@@ -784,7 +784,7 @@ static int jffs2_rename (struct inode *o
+ 	uint8_t type;
+ 	uint32_t now;
+ 
+-	if (flags & ~RENAME_WHITEOUT)
++	if (flags & ~(RENAME_WHITEOUT | RENAME_EXCHANGE))
+ 		return -EINVAL;
+ 
+ 	/* The VFS will check for us and prevent trying to rename a
+@@ -792,7 +792,7 @@ static int jffs2_rename (struct inode *o
+ 	 * the VFS can't check whether the victim is empty. The filesystem
+ 	 * needs to do that for itself.
+ 	 */
+-	if (new_dentry->d_inode) {
++	if (new_dentry->d_inode && !(flags & RENAME_EXCHANGE)) {
+ 		victim_f = JFFS2_INODE_INFO(new_dentry->d_inode);
+ 		if (S_ISDIR(new_dentry->d_inode->i_mode)) {
+ 			struct jffs2_full_dirent *fd;
+@@ -827,7 +827,7 @@ static int jffs2_rename (struct inode *o
+ 	if (ret)
+ 		return ret;
+ 
+-	if (victim_f) {
++	if (victim_f && !(flags & RENAME_EXCHANGE)) {
+ 		/* There was a victim. Kill it off nicely */
+ 		if (S_ISDIR(new_dentry->d_inode->i_mode))
+ 			clear_nlink(new_dentry->d_inode);
+@@ -853,6 +853,12 @@ static int jffs2_rename (struct inode *o
+ 	if (flags & RENAME_WHITEOUT)
+ 		/* Replace with whiteout */
+ 		ret = jffs2_whiteout(old_dir_i, old_dentry);
++	else if (flags & RENAME_EXCHANGE)
++		/* Replace the original */
++		ret = jffs2_do_link(c, JFFS2_INODE_INFO(old_dir_i),
++				    new_dentry->d_inode->i_ino, type,
++				    old_dentry->d_name.name, old_dentry->d_name.len,
++				    now);
+ 	else
+ 		/* Unlink the original */
+ 		ret = jffs2_do_unlink(c, JFFS2_INODE_INFO(old_dir_i),
+@@ -879,7 +885,7 @@ static int jffs2_rename (struct inode *o
+ 		return ret;
+ 	}
+ 
+-	if (S_ISDIR(old_dentry->d_inode->i_mode))
++	if (S_ISDIR(old_dentry->d_inode->i_mode) && !(flags & RENAME_EXCHANGE))
+ 		drop_nlink(old_dir_i);
+ 
+ 	new_dir_i->i_mtime = new_dir_i->i_ctime = old_dir_i->i_mtime = old_dir_i->i_ctime = ITIME(now);

target/linux/generic/patches-4.0/111-jffs2-add-RENAME_EXCHANGE-support.patch

+From: Felix Fietkau <nbd@openwrt.org>
+Date: Sat, 25 Apr 2015 12:41:32 +0200
+Subject: [PATCH] jffs2: add RENAME_EXCHANGE support
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+---
+
+--- a/fs/jffs2/dir.c
++++ b/fs/jffs2/dir.c
+@@ -784,7 +784,7 @@ static int jffs2_rename (struct inode *o
+ 	uint8_t type;
+ 	uint32_t now;
+ 
+-	if (flags & ~RENAME_WHITEOUT)
++	if (flags & ~(RENAME_WHITEOUT | RENAME_EXCHANGE))
+ 		return -EINVAL;
+ 
+ 	/* The VFS will check for us and prevent trying to rename a
+@@ -792,7 +792,7 @@ static int jffs2_rename (struct inode *o
+ 	 * the VFS can't check whether the victim is empty. The filesystem
+ 	 * needs to do that for itself.
+ 	 */
+-	if (new_dentry->d_inode) {
++	if (new_dentry->d_inode && !(flags & RENAME_EXCHANGE)) {
+ 		victim_f = JFFS2_INODE_INFO(new_dentry->d_inode);
+ 		if (d_is_dir(new_dentry)) {
+ 			struct jffs2_full_dirent *fd;
+@@ -827,7 +827,7 @@ static int jffs2_rename (struct inode *o
+ 	if (ret)
+ 		return ret;
+ 
+-	if (victim_f) {
++	if (victim_f && !(flags & RENAME_EXCHANGE)) {
+ 		/* There was a victim. Kill it off nicely */
+ 		if (d_is_dir(new_dentry))
+ 			clear_nlink(new_dentry->d_inode);
+@@ -853,6 +853,12 @@ static int jffs2_rename (struct inode *o
+ 	if (flags & RENAME_WHITEOUT)
+ 		/* Replace with whiteout */
+ 		ret = jffs2_whiteout(old_dir_i, old_dentry);
++	else if (flags & RENAME_EXCHANGE)
++		/* Replace the original */
++		ret = jffs2_do_link(c, JFFS2_INODE_INFO(old_dir_i),
++				    new_dentry->d_inode->i_ino, type,
++				    old_dentry->d_name.name, old_dentry->d_name.len,
++				    now);
+ 	else
+ 		/* Unlink the original */
+ 		ret = jffs2_do_unlink(c, JFFS2_INODE_INFO(old_dir_i),
+@@ -879,7 +885,7 @@ static int jffs2_rename (struct inode *o
+ 		return ret;
+ 	}
+ 
+-	if (d_is_dir(old_dentry))
++	if (d_is_dir(old_dentry) && !(flags & RENAME_EXCHANGE))
+ 		drop_nlink(old_dir_i);
+ 
+ 	new_dir_i->i_mtime = new_dir_i->i_ctime = old_dir_i->i_mtime = old_dir_i->i_ctime = ITIME(now);