| Message ID | 1591109733-14159-1-git-send-email-pooja.trivedi@stackpath.com |
|---|---|
| State | RFC |
| Delegated to: | David Miller |
| Headers | show |
--- a/fs/splice.c +++ b/fs/splice.c @@ -980,10 +980,12 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, * If this is the last data and SPLICE_F_MORE was not set * initially, clears it. */ - if (read_len < len) - sd->flags |= SPLICE_F_MORE; - else if (!more) + if (read_len < len) { + if (pos < i_size_read(file_inode(in))) + sd->flags |= SPLICE_F_MORE; + } else if (!more) sd->flags &= ~SPLICE_F_MORE; + } Sending a followup patch to this that adds a selftest
When sendfile is used for kTLS file delivery and the size provided to sendfile via its 'count' parameter is greater than the file size, kTLS fails to send the file correctly. The last chunk of the file is not sent, and the data integrity of the file is compromised on the receiver side. Based on studying the sendfile source code, in such a case, last chunk of the file will be passed with the MSG_MORE flag set. Following snippet from fs/splice.c:1814 shows code within the while loop in splice_direct_to_actor() function that sets this flag: -------- /* * If more data is pending, set SPLICE_F_MORE * If this is the last data and SPLICE_F_MORE * was not set initially, clears it. */ if (read_len < len) sd->flags |= SPLICE_F_MORE; else if (!more) sd->flags &= ~SPLICE_F_MORE; -------- Due to this, tls layer adds the chunk to the pending records, but does not push it. Following lines of code from tls_sw_do_sendpage() function in tls_sw.c:1153 show the end of record (eor) variable being set based on MSG_MORE flag: -------- bool eor; eor = !(flags & (MSG_MORE | MSG_SENDPAGE_NOTLAST)); -------- This eor bool is then used in the condition check for full_record, end of record, or sk_msg_full in tls_sw_do_sendpage() function in tls_sw.c:1212: -------- if (full_record || eor || sk_msg_full(msg_pl)) { ret = bpf_exec_tx_verdict(msg_pl, sk, full_record, record_type, &copied, flags); if (ret) { if (ret == -EINPROGRESS) num_async++; else if (ret == -ENOMEM) goto wait_for_memory; else if (ret != -EAGAIN) { if (ret == -ENOSPC) ret = 0; goto sendpage_end; } } } continue; -------- Changing the code in splice_direct_to_actor() function in fs/splice.c to detect end of file by checking 'pos' variable against file size, and setting MSG_MORE flag only when EOF is not reached, fixes the issue: that helps reproduce the issue.