kernel: Fix the incorrect i_nlink count after jffs2's RENAME_EXCHANGE operations.

The problem is caused by the incorrect handling of the parent inode's
i_nlink count for the dentry to be RENAME_EXCHANGED. There are 3 cases
to consider. Assume we want to RENAME_EXCHANGE struct dentry *a and
struct dentry *b, and inode_a is pointed to by dentry_a, inode_b is
pointed to by dentry_b:

1. If inode_a is a directory, but inode_b isn't, then we must decrease
   the i_nlink count of old_dir_i, and increase the i_nlink of new_dir_i.
2. If inode_a isn't a directory, but inode_b is a directory, then we
   must increase the i_nlink of old_dir_i, and decrease the i_nlink count
   of new_dir_i.
3. If the types of inode_a and inode_b are the same, we don't change the
   i_nlink for either old_dir_i or new_dir_i.

Signed-off-by: Jing Qiu <aqiu0720@gmail.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/target/linux/generic/patches-4.4/111-jffs2-add-RENAME_EXCHANGE-support.patch b/target/linux/generic/patches-4.4/111-jffs2-add-RENAME_EXCHANGE-support.patch
index b62408717e484f87cfd30e88f7d1cf99034d6c1b..37eb073df968eb1c1de620ecab828edb7c16c555 100644 (file)
--- a/target/linux/generic/patches-4.4/111-jffs2-add-RENAME_EXCHANGE-support.patch
+++ b/target/linux/generic/patches-4.4/111-jffs2-add-RENAME_EXCHANGE-support.patch
@@ -7,7 +7,12 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
 
 --- a/fs/jffs2/dir.c
 +++ b/fs/jffs2/dir.c
-@@ -782,7 +782,7 @@ static int jffs2_rename (struct inode *o
+@@ -779,18 +779,31 @@ 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;
  
@@ -15,8 +20,19 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
 +      if (flags & ~(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
-@@ -790,7 +790,7 @@ static int jffs2_rename (struct inode *o
+        * 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.
         */
@@ -25,7 +41,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
                victim_f = JFFS2_INODE_INFO(d_inode(new_dentry));
                if (d_is_dir(new_dentry)) {
                        struct jffs2_full_dirent *fd;
-@@ -825,7 +825,7 @@ static int jffs2_rename (struct inode *o
+@@ -825,7 +838,7 @@ static int jffs2_rename (struct inode *o
        if (ret)
                return ret;
  
@@ -34,7 +50,14 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
                /* There was a victim. Kill it off nicely */
                if (d_is_dir(new_dentry))
                        clear_nlink(d_inode(new_dentry));
-@@ -851,6 +851,12 @@ static int jffs2_rename (struct inode *o
+@@ -845,12 +858,18 @@ static int jffs2_rename (struct inode *o
+ 
+       /* If it was a directory we moved, and there was no victim,
+          increase i_nlink on its new parent */
+-      if (d_is_dir(old_dentry) && !victim_f)
++      if (d_is_dir(old_dentry) && !victim_f && !(flags & RENAME_EXCHANGE))
+               inc_nlink(new_dir_i);
+ 
        if (flags & RENAME_WHITEOUT)
                /* Replace with whiteout */
                ret = jffs2_whiteout(old_dir_i, old_dentry);
@@ -47,7 +70,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
        else
                /* Unlink the original */
                ret = jffs2_do_unlink(c, JFFS2_INODE_INFO(old_dir_i),
-@@ -882,7 +888,7 @@ static int jffs2_rename (struct inode *o
+@@ -882,7 +901,7 @@ static int jffs2_rename (struct inode *o
                return ret;
        }