openwrt/target/linux/generic/patches-4.9/141-jffs2-add-RENAME_EXCHANGE-support.patch
Jing Qiu 4475da968a 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>
2017-03-16 11:28:40 +01:00

75 lines
2.5 KiB
Diff

From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 25 Apr 2015 12:41:32 +0200
Subject: [PATCH] jffs2: add RENAME_EXCHANGE support
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/fs/jffs2/dir.c
+++ b/fs/jffs2/dir.c
@@ -781,18 +781,31 @@ 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;
@@ -827,7 +840,7 @@ 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));
@@ -853,6 +866,12 @@ 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),
@@ -884,7 +903,7 @@ 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);