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SubjectRe: [PATCH 5/7] shmem: support RENAME_EXCHANGE
On Wed, 23 Jul 2014, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszeredi@suse.cz>
>
> This is really simple in tmpfs since the VFS already takes care of
> shuffling the dentries. Just adjust nlink on parent directories and touch
> c & mtimes.
>
> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
> Cc: Hugh Dickins <hughd@google.com>

Acked-by: Hugh Dickins <hughd@google.com>

> ---
> mm/shmem.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 791b05514f9a..75d5ac806f1e 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2016,6 +2016,28 @@ static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
> return shmem_unlink(dir, dentry);
> }
>
> +static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
> +{
> + bool old_is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
> + bool new_is_dir = S_ISDIR(new_dentry->d_inode->i_mode);
> +
> + if (old_dir != new_dir && old_is_dir != new_is_dir) {
> + if (old_is_dir) {
> + drop_nlink(old_dir);
> + inc_nlink(new_dir);
> + } else {
> + drop_nlink(new_dir);
> + inc_nlink(old_dir);
> + }
> + }
> + old_dir->i_ctime = old_dir->i_mtime =
> + new_dir->i_ctime = new_dir->i_mtime =
> + old_dentry->d_inode->i_ctime =
> + new_dentry->d_inode->i_ctime = CURRENT_TIME;
> +
> + return 0;
> +}
> +
> /*
> * The VFS layer already does all the dentry stuff for rename,
> * we just have to decrement the usage count for the target if
> @@ -2027,9 +2049,12 @@ static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struc
> struct inode *inode = old_dentry->d_inode;
> int they_are_dirs = S_ISDIR(inode->i_mode);
>
> - if (flags & ~(RENAME_NOREPLACE))
> + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
> return -EINVAL;
>
> + if (flags & RENAME_EXCHANGE)
> + return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
> +
> if (!simple_empty(new_dentry))
> return -ENOTEMPTY;
>
> --
> 1.8.1.4


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