nfs: allow intra-file CLONE

Originally CLONE didn't allow for intra-file clones, but we recently
updated the spec to support this feature which is also supported by
local Linux file systems.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index e45f686a5a60fd8a292d7c3a608797e420c24e86..61f1c1c02d06b82126b25f308f79e1f43de6da9c 100644 (file)
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -203,6 +203,7 @@ nfs42_ioctl_clone(struct file *dst_file, unsigned long srcfd,
        struct fd src_file;
        struct inode *src_inode;
        unsigned int bs = server->clone_blksize;
+       bool same_inode = false;
        int ret;
 
        /* dst file must be opened for writing */
@@ -221,10 +222,8 @@ nfs42_ioctl_clone(struct file *dst_file, unsigned long srcfd,
 
        src_inode = file_inode(src_file.file);
 
-       /* src and dst must be different files */
-       ret = -EINVAL;
        if (src_inode == dst_inode)
-               goto out_fput;
+               same_inode = true;
 
        /* src file must be opened for reading */
        if (!(src_file.file->f_mode & FMODE_READ))
@@ -249,8 +248,16 @@ nfs42_ioctl_clone(struct file *dst_file, unsigned long srcfd,
                        goto out_fput;
        }
 
+       /* verify if ranges are overlapped within the same file */
+       if (same_inode) {
+               if (dst_off + count > src_off && dst_off < src_off + count)
+                       goto out_fput;
+       }
+
        /* XXX: do we lock at all? what if server needs CB_RECALL_LAYOUT? */
-       if (dst_inode < src_inode) {
+       if (same_inode) {
+               mutex_lock(&src_inode->i_mutex);
+       } else if (dst_inode < src_inode) {
                mutex_lock_nested(&dst_inode->i_mutex, I_MUTEX_PARENT);
                mutex_lock_nested(&src_inode->i_mutex, I_MUTEX_CHILD);
        } else {
@@ -275,7 +282,9 @@ nfs42_ioctl_clone(struct file *dst_file, unsigned long srcfd,
                truncate_inode_pages_range(&dst_inode->i_data, dst_off, dst_off + count - 1);
 
 out_unlock:
-       if (dst_inode < src_inode) {
+       if (same_inode) {
+               mutex_unlock(&src_inode->i_mutex);
+       } else if (dst_inode < src_inode) {
                mutex_unlock(&src_inode->i_mutex);
                mutex_unlock(&dst_inode->i_mutex);
        } else {