Re: Crash on WRITE SAME
On 7/2/2014 9:36 PM, Christoph Hellwig wrote: On Wed, Jul 02, 2014 at 02:29:05PM -0400, Mikulas Patocka wrote: And what about protection information for commands that transfer partial sectors? (for example, UMAP transfers 24 bytes). Should scsi_transfer_length return 24 or 32 in this case? As far as I understand so far PI is only defined for READ/WRITE commands. But I'll defer to Martin who is a much better source for information on this topic. hch is correct, PI supported operations are (stated in SBC) a) COMPARE AND WRITE; b) ORWRITE (16); c) ORWRITE (32); d) READ (10); e) READ (12); f) READ (16); g) READ (32); h) VERIFY (10); i) VERIFY (12); j) VERIFY (16); k) VERIFY (32); l) WRITE (10); m) WRITE (12); n) WRITE (16); o) WRITE (32); p) WRITE AND VERIFY (10); q) WRITE AND VERIFY (12); r) WRITE AND VERIFY (16); s) WRITE AND VERIFY (32); t) WRITE SAME (10); u) WRITE SAME (16); v) WRITE SAME (32); y) XDWRITEREAD (10); z) XDWRITEREAD (32); aa) XPWRITE (10); and ab) XPWRITE (32). Sagi. -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Crash on WRITE SAME
Hi Sagi Your commit d77e65350f2d82dfa0557707d505711f5a43c8fd causes crash on SCSI WRITE SAME command (it can be triggered by issuing the BLKZEROOUT ioctl). The crash happens in iscsi_tcp_segment_done because sg_next returns NULL. Before that commit, there was this code in iscsi_prep_scsi_cmd_pdu: unsigned out_len = scsi_out(sc)-length; after the commit, there is this: transfer_length = scsi_transfer_length(sc); ... scsi_transfer_length(struct scsi_cmnd *scmd) returns blk_rq_bytes(scmd-request); The problem is this: suppose that we have WRITE_SAME command that writes two 512-byte sectors. blk_rq_bytes(scmd-request) returns 1024 (because 1024 bytes are written to the disk), but scsi_out(sc)-length contains the value 512 (because only 512 bytes are transferred as data for the SCSI command). Your patch changes that from 512 to 1024 and it causes the crash in iscsi_tcp_segment_done due to mismatching size. I'm not exactly sure how to fix this bug in order to not break something else. I'd like to know what was your intention for the function scsi_transfer_length? Is it supposed to return the size of data transferred on the SCSI bus? What should it return for bidirectional commands? scsi_transfer_length tries to add 8 for each transferred sector depending on prot_op. What should it do with commands that transfer only part of a sector? (for example the UNMAP command only transfers 24 bytes of data). Should it add 8 for a partial sector tranferred or not? Mikulas -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Crash on WRITE SAME
On Wed, Jul 02, 2014 at 02:05:14PM -0400, Mikulas Patocka wrote: Hi Sagi Your commit d77e65350f2d82dfa0557707d505711f5a43c8fd causes crash on SCSI WRITE SAME command (it can be triggered by issuing the BLKZEROOUT ioctl). The crash happens in iscsi_tcp_segment_done because sg_next returns NULL. Martin already fixes this over a week ago, we're just waiting for James to send a pull request to Linus. Get this fix from the core-for-3.16 branch of git.infradead.org/users/hch/scsi-queue.git for now. -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Crash on WRITE SAME
On Wed, 2 Jul 2014, Christoph Hellwig wrote: On Wed, Jul 02, 2014 at 02:05:14PM -0400, Mikulas Patocka wrote: Hi Sagi Your commit d77e65350f2d82dfa0557707d505711f5a43c8fd causes crash on SCSI WRITE SAME command (it can be triggered by issuing the BLKZEROOUT ioctl). The crash happens in iscsi_tcp_segment_done because sg_next returns NULL. Martin already fixes this over a week ago, we're just waiting for James to send a pull request to Linus. Get this fix from the core-for-3.16 branch of git.infradead.org/users/hch/scsi-queue.git for now. I see. And what about protection information for commands that transfer partial sectors? (for example, UMAP transfers 24 bytes). Should scsi_transfer_length return 24 or 32 in this case? Mikulas -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Crash on WRITE SAME
On Wed, Jul 02, 2014 at 02:29:05PM -0400, Mikulas Patocka wrote: And what about protection information for commands that transfer partial sectors? (for example, UMAP transfers 24 bytes). Should scsi_transfer_length return 24 or 32 in this case? As far as I understand so far PI is only defined for READ/WRITE commands. But I'll defer to Martin who is a much better source for information on this topic. -- To unsubscribe from this list: send the line unsubscribe linux-scsi in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
