I like allowing those clones. However ...
On 30.01.2012 10:14, Li Zefan wrote:
> It's safe and easy to do so, provided the ranges don't overlap.
>
> Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/ioctl.c | 23 ++++++++++++++++-------
> 1 files changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 0b06a5c..8fcd671 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2223,8 +2223,6 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
> * decompress into destination's address_space (the file offset
> * may change, so source mapping won't do), then recompress (or
> * otherwise reinsert) a subrange.
> - * - allow ranges within the same file to be cloned (provided
> - * they don't overlap)?
> */
>
> /* the destination must be opened for writing */
> @@ -2247,8 +2245,6 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
> src = src_file->f_dentry->d_inode;
>
> ret = -EINVAL;
> - if (src == inode)
> - goto out_fput;
>
> /* the src must be open for reading */
> if (!(src_file->f_mode & FMODE_READ))
> @@ -2282,9 +2278,11 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
> if (inode < src) {
> mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
> mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD);
> - } else {
> + } else if (inode > src) {
> mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT);
> mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
> + } else {
> + mutex_lock(&inode->i_mutex);
> }
>
> /* determine range to clone */
> @@ -2302,6 +2300,13 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
> !IS_ALIGNED(destoff, bs))
> goto out_unlock;
>
> + /*
> + * allow ranges within the same file to be cloned only if
> + * they don't overlap
> + */
> + if (src == inode && !(off + len <= destoff || destoff + len <= off))
^^^^^^^^^^^^
... this check isn't sufficient. Two different inodes can reference the
same data extent and we must prevent overlap cloning there as well.
-Jan
> + goto out_unlock;
> +
> if (destoff > inode->i_size) {
> ret = btrfs_cont_expand(inode, inode->i_size, destoff);
> if (ret)
> @@ -2543,8 +2548,12 @@ out:
> btrfs_release_path(path);
> unlock_extent(&BTRFS_I(src)->io_tree, off, off+len, GFP_NOFS);
> out_unlock:
> - mutex_unlock(&src->i_mutex);
> - mutex_unlock(&inode->i_mutex);
> + if (src != inode) {
> + mutex_unlock(&src->i_mutex);
> + mutex_unlock(&inode->i_mutex);
> + } else {
> + mutex_unlock(&inode->i_mutex);
> + }
> vfree(buf);
> btrfs_free_path(path);
> out_fput:
--
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