Commit 3e51d3c924aea8a1f1372e6c615b0a37b528121d
Committed by
James Bottomley
James Bottomley
1 parent
56dd2c0691
Exists in
master
and in
4 other branches
[SCSI] st: add MTWEOFI to write filemarks without flushing drive buffer
This patch adds a new MTIOCTOP operation MTWEOFI that writes filemarks with immediate bit set. This means that the drive does not flush its buffer and the next file can be started immediately. This speeds up writing in applications that have to write multiple small files. Signed-off-by: Kai Makisara <kai.makisara@kolumbus.fi> Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Showing 3 changed files with 24 additions and 7 deletions Side-by-side Diff
Documentation/scsi/st.txt
| ... | ... | @@ -2,7 +2,7 @@ |
| 2 | 2 | The driver is currently maintained by Kai Mäkisara (email |
| 3 | 3 | Kai.Makisara@kolumbus.fi) |
| 4 | 4 | |
| 5 | -Last modified: Sun Feb 24 21:59:07 2008 by kai.makisara | |
| 5 | +Last modified: Sun Aug 29 18:25:47 2010 by kai.makisara | |
| 6 | 6 | |
| 7 | 7 | |
| 8 | 8 | BASICS |
| ... | ... | @@ -85,6 +85,17 @@ |
| 85 | 85 | optionally written. In both cases end of data is signified by |
| 86 | 86 | returning zero bytes for two consecutive reads. |
| 87 | 87 | |
| 88 | +Writing filemarks without the immediate bit set in the SCSI command block acts | |
| 89 | +as a synchronization point, i.e., all remaining data form the drive buffers is | |
| 90 | +written to tape before the command returns. This makes sure that write errors | |
| 91 | +are caught at that point, but this takes time. In some applications, several | |
| 92 | +consecutive files must be written fast. The MTWEOFI operation can be used to | |
| 93 | +write the filemarks without flushing the drive buffer. Writing filemark at | |
| 94 | +close() is always flushing the drive buffers. However, if the previous | |
| 95 | +operation is MTWEOFI, close() does not write a filemark. This can be used if | |
| 96 | +the program wants to close/open the tape device between files and wants to | |
| 97 | +skip waiting. | |
| 98 | + | |
| 88 | 99 | If rewind, offline, bsf, or seek is done and previous tape operation was |
| 89 | 100 | write, a filemark is written before moving tape. |
| 90 | 101 | |
| ... | ... | @@ -301,6 +312,8 @@ |
| 301 | 312 | MTFSS Space forward over count setmarks. |
| 302 | 313 | MTBSS Space backward over count setmarks. |
| 303 | 314 | MTWEOF Write count filemarks. |
| 315 | +MTWEOFI Write count filemarks with immediate bit set (i.e., does not | |
| 316 | + wait until data is on tape) | |
| 304 | 317 | MTWSM Write count setmarks. |
| 305 | 318 | MTREW Rewind tape. |
| 306 | 319 | MTOFFL Set device off line (often rewind plus eject). |
drivers/scsi/st.c
| ... | ... | @@ -9,7 +9,7 @@ |
| 9 | 9 | Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky, |
| 10 | 10 | Michael Schaefer, J"org Weule, and Eric Youngdale. |
| 11 | 11 | |
| 12 | - Copyright 1992 - 2008 Kai Makisara | |
| 12 | + Copyright 1992 - 2010 Kai Makisara | |
| 13 | 13 | email Kai.Makisara@kolumbus.fi |
| 14 | 14 | |
| 15 | 15 | Some small formal changes - aeb, 950809 |
| ... | ... | @@ -17,7 +17,7 @@ |
| 17 | 17 | Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support |
| 18 | 18 | */ |
| 19 | 19 | |
| 20 | -static const char *verstr = "20081215"; | |
| 20 | +static const char *verstr = "20100829"; | |
| 21 | 21 | |
| 22 | 22 | #include <linux/module.h> |
| 23 | 23 | |
| 24 | 24 | |
| 25 | 25 | |
| ... | ... | @@ -2696,18 +2696,21 @@ |
| 2696 | 2696 | } |
| 2697 | 2697 | break; |
| 2698 | 2698 | case MTWEOF: |
| 2699 | + case MTWEOFI: | |
| 2699 | 2700 | case MTWSM: |
| 2700 | 2701 | if (STp->write_prot) |
| 2701 | 2702 | return (-EACCES); |
| 2702 | 2703 | cmd[0] = WRITE_FILEMARKS; |
| 2703 | 2704 | if (cmd_in == MTWSM) |
| 2704 | 2705 | cmd[1] = 2; |
| 2706 | + if (cmd_in == MTWEOFI) | |
| 2707 | + cmd[1] |= 1; | |
| 2705 | 2708 | cmd[2] = (arg >> 16); |
| 2706 | 2709 | cmd[3] = (arg >> 8); |
| 2707 | 2710 | cmd[4] = arg; |
| 2708 | 2711 | timeout = STp->device->request_queue->rq_timeout; |
| 2709 | 2712 | DEBC( |
| 2710 | - if (cmd_in == MTWEOF) | |
| 2713 | + if (cmd_in != MTWSM) | |
| 2711 | 2714 | printk(ST_DEB_MSG "%s: Writing %d filemarks.\n", name, |
| 2712 | 2715 | cmd[2] * 65536 + cmd[3] * 256 + cmd[4]); |
| 2713 | 2716 | else |
| ... | ... | @@ -2883,8 +2886,8 @@ |
| 2883 | 2886 | else if (chg_eof) |
| 2884 | 2887 | STps->eof = ST_NOEOF; |
| 2885 | 2888 | |
| 2886 | - if (cmd_in == MTWEOF) | |
| 2887 | - STps->rw = ST_IDLE; | |
| 2889 | + if (cmd_in == MTWEOF || cmd_in == MTWEOFI) | |
| 2890 | + STps->rw = ST_IDLE; /* prevent automatic WEOF at close */ | |
| 2888 | 2891 | } else { /* SCSI command was not completely successful. Don't return |
| 2889 | 2892 | from this block without releasing the SCSI command block! */ |
| 2890 | 2893 | struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat; |
| ... | ... | @@ -2901,7 +2904,7 @@ |
| 2901 | 2904 | else |
| 2902 | 2905 | undone = 0; |
| 2903 | 2906 | |
| 2904 | - if (cmd_in == MTWEOF && | |
| 2907 | + if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) && | |
| 2905 | 2908 | cmdstatp->have_sense && |
| 2906 | 2909 | (cmdstatp->flags & SENSE_EOM)) { |
| 2907 | 2910 | if (cmdstatp->sense_hdr.sense_key == NO_SENSE || |
include/linux/mtio.h
| ... | ... | @@ -63,6 +63,7 @@ |
| 63 | 63 | #define MTCOMPRESSION 32/* control compression with SCSI mode page 15 */ |
| 64 | 64 | #define MTSETPART 33 /* Change the active tape partition */ |
| 65 | 65 | #define MTMKPART 34 /* Format the tape with one or two partitions */ |
| 66 | +#define MTWEOFI 35 /* write an end-of-file record (mark) in immediate mode */ | |
| 66 | 67 | |
| 67 | 68 | /* structure for MTIOCGET - mag tape get status command */ |
| 68 | 69 |