ext4: support RENAME_WHITEOUT
Add whiteout support to ext4_rename(). A whiteout inode (chrdev/0,0) is
created before the rename takes place. The whiteout inode is added to the
old entry instead of deleting it.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 603e4eb..aba86e8 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3190,6 +3190,39 @@
}
}
+static struct inode *ext4_whiteout_for_rename(struct ext4_renament *ent,
+ int credits, handle_t **h)
+{
+ struct inode *wh;
+ handle_t *handle;
+ int retries = 0;
+
+ /*
+ * for inode block, sb block, group summaries,
+ * and inode bitmap
+ */
+ credits += (EXT4_MAXQUOTAS_TRANS_BLOCKS(ent->dir->i_sb) +
+ EXT4_XATTR_TRANS_BLOCKS + 4);
+retry:
+ wh = ext4_new_inode_start_handle(ent->dir, S_IFCHR | WHITEOUT_MODE,
+ &ent->dentry->d_name, 0, NULL,
+ EXT4_HT_DIR, credits);
+
+ handle = ext4_journal_current_handle();
+ if (IS_ERR(wh)) {
+ if (handle)
+ ext4_journal_stop(handle);
+ if (PTR_ERR(wh) == -ENOSPC &&
+ ext4_should_retry_alloc(ent->dir->i_sb, &retries))
+ goto retry;
+ } else {
+ *h = handle;
+ init_special_inode(wh, wh->i_mode, WHITEOUT_DEV);
+ wh->i_op = &ext4_special_inode_operations;
+ }
+ return wh;
+}
+
/*
* Anybody can rename anything with this: the permission checks are left to the
* higher-level routines.
@@ -3199,7 +3232,8 @@
* This comes from rename(const char *oldpath, const char *newpath)
*/
static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry)
+ struct inode *new_dir, struct dentry *new_dentry,
+ unsigned int flags)
{
handle_t *handle = NULL;
struct ext4_renament old = {
@@ -3214,6 +3248,9 @@
};
int force_reread;
int retval;
+ struct inode *whiteout = NULL;
+ int credits;
+ u8 old_file_type;
dquot_initialize(old.dir);
dquot_initialize(new.dir);
@@ -3252,11 +3289,17 @@
if (new.inode && !test_opt(new.dir->i_sb, NO_AUTO_DA_ALLOC))
ext4_alloc_da_blocks(old.inode);
- handle = ext4_journal_start(old.dir, EXT4_HT_DIR,
- (2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
- EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2));
- if (IS_ERR(handle))
- return PTR_ERR(handle);
+ credits = (2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
+ EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2);
+ if (!(flags & RENAME_WHITEOUT)) {
+ handle = ext4_journal_start(old.dir, EXT4_HT_DIR, credits);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+ } else {
+ whiteout = ext4_whiteout_for_rename(&old, credits, &handle);
+ if (IS_ERR(whiteout))
+ return PTR_ERR(whiteout);
+ }
if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
ext4_handle_sync(handle);
@@ -3284,13 +3327,26 @@
*/
force_reread = (new.dir->i_ino == old.dir->i_ino &&
ext4_test_inode_flag(new.dir, EXT4_INODE_INLINE_DATA));
+
+ old_file_type = old.de->file_type;
+ if (whiteout) {
+ /*
+ * Do this before adding a new entry, so the old entry is sure
+ * to be still pointing to the valid old entry.
+ */
+ retval = ext4_setent(handle, &old, whiteout->i_ino,
+ EXT4_FT_CHRDEV);
+ if (retval)
+ goto end_rename;
+ ext4_mark_inode_dirty(handle, whiteout);
+ }
if (!new.bh) {
retval = ext4_add_entry(handle, new.dentry, old.inode);
if (retval)
goto end_rename;
} else {
retval = ext4_setent(handle, &new,
- old.inode->i_ino, old.de->file_type);
+ old.inode->i_ino, old_file_type);
if (retval)
goto end_rename;
}
@@ -3305,10 +3361,12 @@
old.inode->i_ctime = ext4_current_time(old.inode);
ext4_mark_inode_dirty(handle, old.inode);
- /*
- * ok, that's it
- */
- ext4_rename_delete(handle, &old, force_reread);
+ if (!whiteout) {
+ /*
+ * ok, that's it
+ */
+ ext4_rename_delete(handle, &old, force_reread);
+ }
if (new.inode) {
ext4_dec_count(handle, new.inode);
@@ -3344,6 +3402,12 @@
brelse(old.dir_bh);
brelse(old.bh);
brelse(new.bh);
+ if (whiteout) {
+ if (retval)
+ drop_nlink(whiteout);
+ unlock_new_inode(whiteout);
+ iput(whiteout);
+ }
if (handle)
ext4_journal_stop(handle);
return retval;
@@ -3476,18 +3540,15 @@
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
- if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
return -EINVAL;
if (flags & RENAME_EXCHANGE) {
return ext4_cross_rename(old_dir, old_dentry,
new_dir, new_dentry);
}
- /*
- * Existence checking was done by the VFS, otherwise "RENAME_NOREPLACE"
- * is equivalent to regular rename.
- */
- return ext4_rename(old_dir, old_dentry, new_dir, new_dentry);
+
+ return ext4_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
}
/*