OpenWrt – Rev 1

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From: Felix Fietkau <nbd@nbd.name>
Subject: jffs2: add RENAME_EXCHANGE support

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

--- a/fs/jffs2/dir.c
+++ b/fs/jffs2/dir.c
@@ -777,18 +777,31 @@ static int jffs2_rename (struct inode *o
        int ret;
        struct jffs2_sb_info *c = JFFS2_SB_INFO(old_dir_i->i_sb);
        struct jffs2_inode_info *victim_f = NULL;
+       struct inode *fst_inode = d_inode(old_dentry);
+       struct inode *snd_inode = d_inode(new_dentry);
        uint8_t type;
        uint32_t now;
 
-       if (flags & ~(RENAME_NOREPLACE|RENAME_WHITEOUT))
+       if (flags & ~(RENAME_NOREPLACE|RENAME_WHITEOUT|RENAME_EXCHANGE))
                return -EINVAL;
 
+       if ((flags & RENAME_EXCHANGE) && (old_dir_i != new_dir_i)) {
+               if (S_ISDIR(fst_inode->i_mode) && !S_ISDIR(snd_inode->i_mode)) {
+                       inc_nlink(new_dir_i);
+                       drop_nlink(old_dir_i);
+               }
+               else if (!S_ISDIR(fst_inode->i_mode) && S_ISDIR(snd_inode->i_mode)) {
+                       drop_nlink(new_dir_i);
+                       inc_nlink(old_dir_i);
+               }
+       }
+
        /* The VFS will check for us and prevent trying to rename a
         * file over a directory and vice versa, but if it's a directory,
         * the VFS can't check whether the victim is empty. The filesystem
         * needs to do that for itself.
         */
-       if (d_really_is_positive(new_dentry)) {
+       if (d_really_is_positive(new_dentry) && !(flags & RENAME_EXCHANGE)) {
                victim_f = JFFS2_INODE_INFO(d_inode(new_dentry));
                if (d_is_dir(new_dentry)) {
                        struct jffs2_full_dirent *fd;
@@ -823,7 +836,7 @@ 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(d_inode(new_dentry));
@@ -849,6 +862,12 @@ 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),
+                                   d_inode(new_dentry)->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),
@@ -880,7 +899,7 @@ 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);