1 files changed, 100 insertions, 0 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 60ee26941231..2116e74a83d3 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1523,3 +1523,103 @@ int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
         return ret;
 }
 EXPORT_SYMBOL(vfs_clone_file_range);
+
+int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
+{
+        struct file_dedupe_range_info *info;
+        struct inode *src = file_inode(file);
+        u64 off;
+        u64 len;
+        int i;
+        int ret;
+        bool is_admin = capable(CAP_SYS_ADMIN);
+        u16 count = same->dest_count;
+        struct file *dst_file;
+        loff_t dst_off;
+        ssize_t deduped;
+
+        if (!(file->f_mode & FMODE_READ))
+                return -EINVAL;
+
+        if (same->reserved1 || same->reserved2)
+                return -EINVAL;
+
+        off = same->src_offset;
+        len = same->src_length;
+
+        ret = -EISDIR;
+        if (S_ISDIR(src->i_mode))
+                goto out;
+
+        ret = -EINVAL;
+        if (!S_ISREG(src->i_mode))
+                goto out;
+
+        ret = clone_verify_area(file, off, len, false);
+        if (ret < 0)
+                goto out;
+        ret = 0;
+
+        /* pre-format output fields to sane values */
+        for (i = 0; i < count; i++) {
+                same->info[i].bytes_deduped = 0ULL;
+                same->info[i].status = FILE_DEDUPE_RANGE_SAME;
+        }
+
+        for (i = 0, info = same->info; i < count; i++, info++) {
+                struct inode *dst;
+                struct fd dst_fd = fdget(info->dest_fd);
+
+                dst_file = dst_fd.file;
+                if (!dst_file) {
+                        info->status = -EBADF;
+                        goto next_loop;
+                }
+                dst = file_inode(dst_file);
+
+                ret = mnt_want_write_file(dst_file);
+                if (ret) {
+                        info->status = ret;
+                        goto next_loop;
+                }
+
+                dst_off = info->dest_offset;
+                ret = clone_verify_area(dst_file, dst_off, len, true);
+                if (ret < 0) {
+                        info->status = ret;
+                        goto next_file;
+                }
+                ret = 0;
+
+                if (info->reserved) {
+                        info->status = -EINVAL;
+                } else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) {
+                        info->status = -EINVAL;
+                } else if (file->f_path.mnt != dst_file->f_path.mnt) {
+                        info->status = -EXDEV;
+                } else if (S_ISDIR(dst->i_mode)) {
+                        info->status = -EISDIR;
+                } else if (dst_file->f_op->dedupe_file_range == NULL) {
+                        info->status = -EINVAL;
+                } else {
+                        deduped = dst_file->f_op->dedupe_file_range(file, off,
+                                                        len, dst_file,
+                                                        info->dest_offset);
+                        if (deduped == -EBADE)
+                                info->status = FILE_DEDUPE_RANGE_DIFFERS;
+                        else if (deduped < 0)
+                                info->status = deduped;
+                        else
+                                info->bytes_deduped += deduped;
+                }
+
+next_file:
+                mnt_drop_write_file(dst_file);
+next_loop:
+                fdput(dst_fd);
+        }
+
+out:
+        return ret;
+}
+EXPORT_SYMBOL(vfs_dedupe_file_range);