On Wed, 15 Feb 2012, Lee Duncan wrote: > 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 flag 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 can be enabled via a new module flag: st_nowait_eof. > It can also be set or cleared via the MTSETDRVBUFFER ioctl, using > the newly-defined MT_ST_NOWAIT_EOF flag. > > Lastly, this new feature is displayed via the sysfs tape "options" > attribute. > > Signed-off-by: Lee Duncan <lduncan@xxxxxxxx> > --- > Documentation/scsi/st.txt | 2 ++ > drivers/scsi/st.c | 24 +++++++++++++++++++++--- > drivers/scsi/st.h | 1 + > include/linux/mtio.h | 1 + > 4 files changed, 25 insertions(+), 3 deletions(-) > > diff --git a/Documentation/scsi/st.txt b/Documentation/scsi/st.txt > index 691ca29..85c1b1a 100644 > --- a/Documentation/scsi/st.txt > +++ b/Documentation/scsi/st.txt > @@ -390,6 +390,8 @@ MTSETDRVBUFFER > MT_ST_SYSV sets the SYSV semantics (mode) > MT_ST_NOWAIT enables immediate mode (i.e., don't wait for > the command to finish) for some commands (e.g., rewind) > + MT_ST_NOWAIT_EOF enables immediate filemark mode (i.e. when > + writing a filemark, don't wait for it to complete) You could add a note that errors before EOF may not be noticed. > MT_ST_SILI enables setting the SILI bit in SCSI commands when > reading in variable block mode to enhance performance when > reading blocks shorter than the byte count; set this only > diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c > index 9b28f39..f18d10b 100644 > --- a/drivers/scsi/st.c > +++ b/drivers/scsi/st.c > @@ -81,6 +81,7 @@ static int max_sg_segs; > static int try_direct_io = TRY_DIRECT_IO; > static int try_rdio = 1; > static int try_wdio = 1; > +static int st_nowait_eof; > > static int st_dev_max; > static int st_nr_dev; > @@ -103,6 +104,8 @@ module_param_named(max_sg_segs, max_sg_segs, int, 0); > MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)"); > module_param_named(try_direct_io, try_direct_io, int, 0); > MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)"); > +module_param_named(st_nowait_eof, st_nowait_eof, int, 0); > +MODULE_PARM_DESC(st_nowait_eof, "Do not wait when writing EOF (filemark) (0)"); > I think this should not be a module option. The property should be settable only as a mode option like other options of this kind. (I may have not written this clearly in my previous reply). Otherwise the patch looks good. Kai -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
