const u64 sz = BTRFS_I(src)->root->fs_info->sectorsize;
len = round_down(i_size_read(src), sz) - loff;
+ if (len == 0)
+ return 0;
olen = len;
}
}
goto out_unlock;
if (len == 0)
olen = len = src->i_size - off;
- /* if we extend to eof, continue to block boundary */
- if (off + len == src->i_size)
+ /*
+ * If we extend to eof, continue to block boundary if and only if the
+ * destination end offset matches the destination file's size, otherwise
+ * we would be corrupting data by placing the eof block into the middle
+ * of a file.
+ */
+ if (off + len == src->i_size) {
+ if (!IS_ALIGNED(len, bs) && destoff + len < inode->i_size)
+ goto out_unlock;
len = ALIGN(src->i_size, bs) - off;
+ }
if (len == 0) {
ret = 0;