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authorLee Duncan <lduncan@suse.com>2012-03-02 00:41:01 +0400
committerJames Bottomley <JBottomley@Parallels.com>2012-03-27 11:26:34 +0400
commitc743e44fbb1f8668941e83de07662b1ecd33d083 (patch)
treec0a5eacf103f566942b8e8e7c222b3fa588657a4 /drivers/scsi/st.c
parent3194eef325c126d1f3bfa28317e2acd78292250d (diff)
downloadlinux-c743e44fbb1f8668941e83de07662b1ecd33d083.tar.xz
[SCSI] st: expand ability to write immediate filemarks
The st tape driver recently added the MTWEOFI ioctl, which writes a tape filemark (EOF), like the MTWEOF ioctl, except that MTWEOFI returns immediately. This makes certain applications, like backup software, run much more quickly on buffered tape drives. Since legacy applications do not know about this new MTWEOFI ioctl, this patch adds a new ioctl option that tells the st driver to return immediately when writing an EOF (i.e. a filemark). This new flag is much like the existing flag that tells the st driver to perform writes (and certain other IOs) immediately, but this new flag only applies to writing EOFs. This new feature is controlled via the MTSETDRVBUFFER ioctl, using the newly-defined MT_ST_NOWAIT_EOF flag. Use of this new feature is displayed via the sysfs tape "options" attribute. The st documentation was updated to mention this new flag, as well as the problems that can occur from using it. Signed-off-by: Lee Duncan <lduncan@suse.com> Acked-by: Kai Makisara <kai.makisara@kolumbus.fi> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers/scsi/st.c')
-rw-r--r--drivers/scsi/st.c21
1 files changed, 18 insertions, 3 deletions
diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 9262cdfa4b23..8c663e16fd02 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -1106,6 +1106,12 @@ static int check_tape(struct scsi_tape *STp, struct file *filp)
STp->drv_buffer));
}
STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
+ if (!STp->drv_buffer && STp->immediate_filemark) {
+ printk(KERN_WARNING
+ "%s: non-buffered tape: disabling writing immediate filemarks\n",
+ name);
+ STp->immediate_filemark = 0;
+ }
}
st_release_request(SRpnt);
SRpnt = NULL;
@@ -1314,6 +1320,8 @@ static int st_flush(struct file *filp, fl_owner_t id)
memset(cmd, 0, MAX_COMMAND_SIZE);
cmd[0] = WRITE_FILEMARKS;
+ if (STp->immediate_filemark)
+ cmd[1] = 1;
cmd[4] = 1 + STp->two_fm;
SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
@@ -2181,8 +2189,9 @@ static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm, char
name, STm->defaults_for_writes, STp->omit_blklims, STp->can_partitions,
STp->scsi2_logical);
printk(KERN_INFO
- "%s: sysv: %d nowait: %d sili: %d\n", name, STm->sysv, STp->immediate,
- STp->sili);
+ "%s: sysv: %d nowait: %d sili: %d nowait_filemark: %d\n",
+ name, STm->sysv, STp->immediate, STp->sili,
+ STp->immediate_filemark);
printk(KERN_INFO "%s: debugging: %d\n",
name, debugging);
}
@@ -2224,6 +2233,7 @@ static int st_set_options(struct scsi_tape *STp, long options)
STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
STp->immediate = (options & MT_ST_NOWAIT) != 0;
+ STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
STm->sysv = (options & MT_ST_SYSV) != 0;
STp->sili = (options & MT_ST_SILI) != 0;
DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
@@ -2255,6 +2265,8 @@ static int st_set_options(struct scsi_tape *STp, long options)
STp->scsi2_logical = value;
if ((options & MT_ST_NOWAIT) != 0)
STp->immediate = value;
+ if ((options & MT_ST_NOWAIT_EOF) != 0)
+ STp->immediate_filemark = value;
if ((options & MT_ST_SYSV) != 0)
STm->sysv = value;
if ((options & MT_ST_SILI) != 0)
@@ -2714,7 +2726,8 @@ static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned lon
cmd[0] = WRITE_FILEMARKS;
if (cmd_in == MTWSM)
cmd[1] = 2;
- if (cmd_in == MTWEOFI)
+ if (cmd_in == MTWEOFI ||
+ (cmd_in == MTWEOF && STp->immediate_filemark))
cmd[1] |= 1;
cmd[2] = (arg >> 16);
cmd[3] = (arg >> 8);
@@ -4093,6 +4106,7 @@ static int st_probe(struct device *dev)
tpnt->scsi2_logical = ST_SCSI2LOGICAL;
tpnt->sili = ST_SILI;
tpnt->immediate = ST_NOWAIT;
+ tpnt->immediate_filemark = 0;
tpnt->default_drvbuffer = 0xff; /* No forced buffering */
tpnt->partition = 0;
tpnt->new_partition = 0;
@@ -4478,6 +4492,7 @@ st_options_show(struct device *dev, struct device_attribute *attr, char *buf)
options |= STp->scsi2_logical ? MT_ST_SCSI2LOGICAL : 0;
options |= STm->sysv ? MT_ST_SYSV : 0;
options |= STp->immediate ? MT_ST_NOWAIT : 0;
+ options |= STp->immediate_filemark ? MT_ST_NOWAIT_EOF : 0;
options |= STp->sili ? MT_ST_SILI : 0;
l = snprintf(buf, PAGE_SIZE, "0x%08x\n", options);