| Message ID | 4AB3B43D.9000802@ce.jp.nec.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Fri, Sep 18 2009 at 12:24pm -0400, Jun'ichi Nomura <j-nomura@ce.jp.nec.com> wrote: > This patch is a preparation for the last patch in this patchset > which changes blk_set_default_limits() to set 0 to max_sectors. should read: changes blk_set_default_limits() to set max_sectors to 0. > dm uses blk_stack_limits() to merge limits of underlying devices > and copy the end result to the queue. > But if there's no underlying device (like 'zero' target), > max_sectors/max_hw_sectors are left unchanged from the default 0 > and just copying it to the queue causes problems. > > Provide blk_queue_copy_limits() to get a safe copy with > invalid values fixed-up. > > Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> > Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> > Cc: David Strand <dpstrand@gmail.com> > Cc: Mike Snitzer <snitzer@redhat.com> > Cc: Alasdair G Kergon <agk@redhat.com> > Cc: Martin K. Petersen <martin.petersen@oracle.com> > Cc: Jens Axboe <jens.axboe@oracle.com> > --- > block/blk-settings.c | 28 ++++++++++++++++++++++++++++ > include/linux/blkdev.h | 1 + > 2 files changed, 29 insertions(+) > > Index: linux-2.6.31.work/block/blk-settings.c > =================================================================== > --- linux-2.6.31.work.orig/block/blk-settings.c > +++ linux-2.6.31.work/block/blk-settings.c > @@ -122,6 +122,34 @@ void blk_set_default_limits(struct queue > EXPORT_SYMBOL(blk_set_default_limits); > > /** > + * blk_queue_copy_limits - copy limits to queue > + * @q: the request queue whose limits as a copy destination > + * @lim: the queue_limits structure as a copy source > + * > + * Description: > + * Copies a queue_limit struct contents to @q with fix-ups to > + * invalid values. > + */ > +void blk_queue_copy_limits(struct request_queue *q, struct queue_limits > *lim) > +{ > + q->limits = *lim; > + > + /* > + * blk_set_default_limits() sets 0 to max_sectors/max_hw_sectors > + * so that blk_stack_limits() appropriately propagate the values > + * of lower-stack by min_not_zero(). > + * However, if the default value 0 is unchanged (e.g. the stacking > + * device is virtual and has no underlying device), it results > + * in unusable device. Likewise: blk_set_default_limits() sets max_sectors/max_hw_sectors to 0? > + * Check if max_sectors/max_hw_sectors have non-zero values, > + * and set SAFE_MAX_SECTORS if they do. > + */ > + if (q->limits.max_sectors == 0 || q->limits.max_hw_sectors == 0) > + blk_queue_max_sectors(q, SAFE_MAX_SECTORS); Shouldn't this check (and the entire comment above it) get added in the 3rd patch once max_sectors/max_hw_sectors sre actually set to 0? I'm being really pedantic here but... -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Sat, Sep 19 2009, Jun'ichi Nomura wrote: > This patch is a preparation for the last patch in this patchset > which changes blk_set_default_limits() to set 0 to max_sectors. > > dm uses blk_stack_limits() to merge limits of underlying devices > and copy the end result to the queue. > But if there's no underlying device (like 'zero' target), > max_sectors/max_hw_sectors are left unchanged from the default 0 > and just copying it to the queue causes problems. > > Provide blk_queue_copy_limits() to get a safe copy with > invalid values fixed-up. Added for 2.6.32.
On Fri, Sep 18 2009, Jens Axboe wrote: > On Sat, Sep 19 2009, Jun'ichi Nomura wrote: > > This patch is a preparation for the last patch in this patchset > > which changes blk_set_default_limits() to set 0 to max_sectors. > > > > dm uses blk_stack_limits() to merge limits of underlying devices > > and copy the end result to the queue. > > But if there's no underlying device (like 'zero' target), > > max_sectors/max_hw_sectors are left unchanged from the default 0 > > and just copying it to the queue causes problems. > > > > Provide blk_queue_copy_limits() to get a safe copy with > > invalid values fixed-up. > > Added for 2.6.32. And removed, it's white space damaged and doesn't apply to the current tree.
Index: linux-2.6.31.work/block/blk-settings.c =================================================================== --- linux-2.6.31.work.orig/block/blk-settings.c +++ linux-2.6.31.work/block/blk-settings.c @@ -122,6 +122,34 @@ void blk_set_default_limits(struct queue EXPORT_SYMBOL(blk_set_default_limits); /** + * blk_queue_copy_limits - copy limits to queue + * @q: the request queue whose limits as a copy destination + * @lim: the queue_limits structure as a copy source + * + * Description: + * Copies a queue_limit struct contents to @q with fix-ups to + * invalid values. + */ +void blk_queue_copy_limits(struct request_queue *q, struct queue_limits *lim) +{ + q->limits = *lim; + + /* + * blk_set_default_limits() sets 0 to max_sectors/max_hw_sectors + * so that blk_stack_limits() appropriately propagate the values + * of lower-stack by min_not_zero(). + * However, if the default value 0 is unchanged (e.g. the stacking + * device is virtual and has no underlying device), it results + * in unusable device. + * Check if max_sectors/max_hw_sectors have non-zero values, + * and set SAFE_MAX_SECTORS if they do. + */ + if (q->limits.max_sectors == 0 || q->limits.max_hw_sectors == 0) + blk_queue_max_sectors(q, SAFE_MAX_SECTORS); +} +EXPORT_SYMBOL(blk_queue_copy_limits); + +/** * blk_queue_make_request - define an alternate make_request function for a device * @q: the request queue for the device to be affected * @mfn: the alternate make_request function Index: linux-2.6.31.work/include/linux/blkdev.h =================================================================== --- linux-2.6.31.work.orig/include/linux/blkdev.h +++ linux-2.6.31.work/include/linux/blkdev.h @@ -917,6 +917,7 @@ extern void blk_limits_io_min(struct que extern void blk_queue_io_min(struct request_queue *q, unsigned int min); extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt); extern void blk_set_default_limits(struct queue_limits *lim); +extern void blk_queue_copy_limits(struct request_queue *q, struct queue_limits *lim); extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, sector_t offset);