Messages in this thread | | | Subject | Re: [RFC 2/6] block: add flag for add_disk() completion notation | From | Hannes Reinecke <> | Date | Fri, 16 Jul 2021 07:49:49 +0200 |
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On 7/15/21 10:23 PM, Luis Chamberlain wrote: > Often drivers may have complex setups where it is not > clear if their disk completed their respective *add_disk*() > call. They either have to invent a setting or, they > incorrectly use GENHD_FL_UP. Using GENHD_FL_UP however is > used internally so we know when we can add / remove > partitions safely. We can easily fail along the way > prior to add_disk() completing and still have > GENHD_FL_UP set, so it would not be correct in that case > to call del_gendisk() on the disk. > > Provide a new flag then which allows us to check if > *add_disk*() completed, and conversely just make > del_gendisk() check for this for drivers so that > they can safely call del_gendisk() and we'll figure > it out if it is safe for you to call this. > > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > --- > block/genhd.c | 8 ++++++++ > include/linux/genhd.h | 11 ++++++++++- > 2 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/block/genhd.c b/block/genhd.c > index c6c9c196ff27..72703d243b44 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -630,6 +630,8 @@ static int __device_add_disk(struct device *parent, struct gendisk *disk, > if (ret) > goto exit_del_events; > > + disk->flags |= GENHD_FL_DISK_ADDED; > + > return 0; > exit_del_events: > disk_del_events(disk); > @@ -677,6 +679,9 @@ EXPORT_SYMBOL(device_add_disk_no_queue_reg); > * with put_disk(), which should be called after del_gendisk(), if > * __device_add_disk() was used. > * > + * Drivers can safely call this even if they are not sure if the respective > + * __device_add_disk() call succeeded. > + * > * Drivers exist which depend on the release of the gendisk to be synchronous, > * it should not be deferred. > * > @@ -686,6 +691,9 @@ void del_gendisk(struct gendisk *disk) > { > might_sleep(); > > + if (!blk_disk_registered(disk)) > + return; > + > if (WARN_ON_ONCE(!disk->queue)) > return; > > diff --git a/include/linux/genhd.h b/include/linux/genhd.h > index dc07a957c9e1..73024416d2d5 100644 > --- a/include/linux/genhd.h > +++ b/include/linux/genhd.h > @@ -56,6 +56,10 @@ struct partition_meta_info { > * Must not be set for devices which are removed entirely when the > * media is removed. > * > + * ``GENHD_FL_DISK_ADDED`` (0x0002): used to clarify that the > + * respective add_disk*() call completed successfully, so that > + * we know we can safely process del_gendisk() on the disk. > + * > * ``GENHD_FL_CD`` (0x0008): the block device is a CD-ROM-style > * device. > * Affects responses to the ``CDROM_GET_CAPABILITY`` ioctl. > @@ -94,7 +98,7 @@ struct partition_meta_info { > * Used for multipath devices. > */ > #define GENHD_FL_REMOVABLE 0x0001 > -/* 2 is unused (used to be GENHD_FL_DRIVERFS) */ > +#define GENHD_FL_DISK_ADDED 0x0002 > /* 4 is unused (used to be GENHD_FL_MEDIA_CHANGE_NOTIFY) */ > #define GENHD_FL_CD 0x0008 > #define GENHD_FL_UP 0x0010 > @@ -189,6 +193,11 @@ struct gendisk { > #define disk_to_cdi(disk) NULL > #endif > > +static inline bool blk_disk_registered(struct gendisk *disk) > +{ > + return disk && (disk->flags & GENHD_FL_DISK_ADDED); > +} > + > static inline int disk_max_parts(struct gendisk *disk) > { > if (disk->flags & GENHD_FL_EXT_DEVT) > Bah. The flag is named 'DISK_ADDED', and the wrapper 'disk_registered'. Please use the same wording (either 'added' or 'registered') for both to avoid confusion.
Cheers,
Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
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