ext4: add cross rename support
Implement RENAME_EXCHANGE flag in renameat2 syscall.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 75f1bde..1cb84f7 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3004,6 +3004,8 @@
struct inode *dir;
struct dentry *dentry;
struct inode *inode;
+ bool is_dir;
+ int dir_nlink_delta;
/* entry for "dentry" */
struct buffer_head *bh;
@@ -3135,6 +3137,17 @@
}
}
+static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent)
+{
+ if (ent->dir_nlink_delta) {
+ if (ent->dir_nlink_delta == -1)
+ ext4_dec_count(handle, ent->dir);
+ else
+ ext4_inc_count(handle, ent->dir);
+ ext4_mark_inode_dirty(handle, ent->dir);
+ }
+}
+
/*
* Anybody can rename anything with this: the permission checks are left to the
* higher-level routines.
@@ -3274,13 +3287,137 @@
return retval;
}
+static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ handle_t *handle = NULL;
+ struct ext4_renament old = {
+ .dir = old_dir,
+ .dentry = old_dentry,
+ .inode = old_dentry->d_inode,
+ };
+ struct ext4_renament new = {
+ .dir = new_dir,
+ .dentry = new_dentry,
+ .inode = new_dentry->d_inode,
+ };
+ u8 new_file_type;
+ int retval;
+
+ dquot_initialize(old.dir);
+ dquot_initialize(new.dir);
+
+ old.bh = ext4_find_entry(old.dir, &old.dentry->d_name,
+ &old.de, &old.inlined);
+ /*
+ * Check for inode number is _not_ due to possible IO errors.
+ * We might rmdir the source, keep it as pwd of some process
+ * and merrily kill the link to whatever was created under the
+ * same name. Goodbye sticky bit ;-<
+ */
+ retval = -ENOENT;
+ if (!old.bh || le32_to_cpu(old.de->inode) != old.inode->i_ino)
+ goto end_rename;
+
+ new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
+ &new.de, &new.inlined);
+
+ /* RENAME_EXCHANGE case: old *and* new must both exist */
+ if (!new.bh || le32_to_cpu(new.de->inode) != new.inode->i_ino)
+ goto end_rename;
+
+ handle = ext4_journal_start(old.dir, EXT4_HT_DIR,
+ (2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
+ 2 * EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2));
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+
+ if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
+ ext4_handle_sync(handle);
+
+ if (S_ISDIR(old.inode->i_mode)) {
+ old.is_dir = true;
+ retval = ext4_rename_dir_prepare(handle, &old);
+ if (retval)
+ goto end_rename;
+ }
+ if (S_ISDIR(new.inode->i_mode)) {
+ new.is_dir = true;
+ retval = ext4_rename_dir_prepare(handle, &new);
+ if (retval)
+ goto end_rename;
+ }
+
+ /*
+ * Other than the special case of overwriting a directory, parents'
+ * nlink only needs to be modified if this is a cross directory rename.
+ */
+ if (old.dir != new.dir && old.is_dir != new.is_dir) {
+ old.dir_nlink_delta = old.is_dir ? -1 : 1;
+ new.dir_nlink_delta = -old.dir_nlink_delta;
+ retval = -EMLINK;
+ if ((old.dir_nlink_delta > 0 && EXT4_DIR_LINK_MAX(old.dir)) ||
+ (new.dir_nlink_delta > 0 && EXT4_DIR_LINK_MAX(new.dir)))
+ goto end_rename;
+ }
+
+ new_file_type = new.de->file_type;
+ retval = ext4_setent(handle, &new, old.inode->i_ino, old.de->file_type);
+ if (retval)
+ goto end_rename;
+
+ retval = ext4_setent(handle, &old, new.inode->i_ino, new_file_type);
+ if (retval)
+ goto end_rename;
+
+ /*
+ * Like most other Unix systems, set the ctime for inodes on a
+ * rename.
+ */
+ old.inode->i_ctime = ext4_current_time(old.inode);
+ new.inode->i_ctime = ext4_current_time(new.inode);
+ ext4_mark_inode_dirty(handle, old.inode);
+ ext4_mark_inode_dirty(handle, new.inode);
+
+ if (old.dir_bh) {
+ retval = ext4_rename_dir_finish(handle, &old, new.dir->i_ino);
+ if (retval)
+ goto end_rename;
+ }
+ if (new.dir_bh) {
+ retval = ext4_rename_dir_finish(handle, &new, old.dir->i_ino);
+ if (retval)
+ goto end_rename;
+ }
+ ext4_update_dir_count(handle, &old);
+ ext4_update_dir_count(handle, &new);
+ retval = 0;
+
+end_rename:
+ brelse(old.dir_bh);
+ brelse(new.dir_bh);
+ brelse(old.bh);
+ brelse(new.bh);
+ if (handle)
+ ext4_journal_stop(handle);
+ return retval;
+}
+
static int ext4_rename2(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
- if (flags & ~RENAME_NOREPLACE)
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
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);
}
