Btrfs: allow file data clone within a file
We did not allow file data clone within the same file because of
deadlock issues.
However, we now use nested lock to avoid deadlock between the
parent directory and the child file.
So it's safe to do file clone within the same file when the two
ranges are not overlapped.
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 015689a..0e17a30 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2486,6 +2486,7 @@
int ret;
u64 len = olen;
u64 bs = root->fs_info->sb->s_blocksize;
+ int same_inode = 0;
/*
* TODO:
@@ -2522,7 +2523,7 @@
ret = -EINVAL;
if (src == inode)
- goto out_fput;
+ same_inode = 1;
/* the src must be open for reading */
if (!(src_file.file->f_mode & FMODE_READ))
@@ -2553,12 +2554,16 @@
}
path->reada = 2;
- if (inode < src) {
- mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
- mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD);
+ if (!same_inode) {
+ if (inode < src) {
+ mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
+ mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD);
+ } else {
+ mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT);
+ mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
+ }
} else {
- mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT);
- mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
+ mutex_lock(&src->i_mutex);
}
/* determine range to clone */
@@ -2576,6 +2581,12 @@
!IS_ALIGNED(destoff, bs))
goto out_unlock;
+ /* verify if ranges are overlapped within the same file */
+ if (same_inode) {
+ if (destoff + len > off && destoff < off + len)
+ goto out_unlock;
+ }
+
if (destoff > inode->i_size) {
ret = btrfs_cont_expand(inode, inode->i_size, destoff);
if (ret)
@@ -2852,7 +2863,8 @@
unlock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1);
out_unlock:
mutex_unlock(&src->i_mutex);
- mutex_unlock(&inode->i_mutex);
+ if (!same_inode)
+ mutex_unlock(&inode->i_mutex);
vfree(buf);
btrfs_free_path(path);
out_fput:
