On 26/02/19 09:07AM, Dave Jiang wrote: > > > On 1/18/26 3:32 PM, John Groves wrote: > > From: John Groves <[email protected]> > > > > The fs_dax_get() function should be called by fs-dax file systems after > > opening a fsdev dax device. This adds holder_operations, which provides > > a memory failure callback path and effects exclusivity between callers > > of fs_dax_get(). > > > > fs_dax_get() is specific to fsdev_dax, so it checks the driver type > > (which required touching bus.[ch]). fs_dax_get() fails if fsdev_dax is > > not bound to the memory. > > > > This function serves the same role as fs_dax_get_by_bdev(), which dax > > file systems call after opening the pmem block device. > > > > This can't be located in fsdev.c because struct dax_device is opaque > > there. > > > > This will be called by fs/fuse/famfs.c in a subsequent commit. > > > > Signed-off-by: John Groves <[email protected]> > > --- > > drivers/dax/bus.c | 2 -- > > drivers/dax/bus.h | 2 ++ > > drivers/dax/super.c | 58 ++++++++++++++++++++++++++++++++++++++++++++- > > include/linux/dax.h | 20 ++++++++++------ > > 4 files changed, 72 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > > index e79daf825b52..01402d5103ef 100644 > > --- a/drivers/dax/bus.c > > +++ b/drivers/dax/bus.c > > @@ -39,8 +39,6 @@ static int dax_bus_uevent(const struct device *dev, > > struct kobj_uevent_env *env) > > return add_uevent_var(env, "MODALIAS=" DAX_DEVICE_MODALIAS_FMT, 0); > > } > > > > -#define to_dax_drv(__drv) container_of_const(__drv, struct > > dax_device_driver, drv) > > - > > static struct dax_id *__dax_match_id(const struct dax_device_driver > > *dax_drv, > > const char *dev_name) > > { > > diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h > > index 880bdf7e72d7..dc6f112ac4a4 100644 > > --- a/drivers/dax/bus.h > > +++ b/drivers/dax/bus.h > > @@ -42,6 +42,8 @@ struct dax_device_driver { > > void (*remove)(struct dev_dax *dev); > > }; > > > > +#define to_dax_drv(__drv) container_of_const(__drv, struct > > dax_device_driver, drv) > > + > > int __dax_driver_register(struct dax_device_driver *dax_drv, > > struct module *module, const char *mod_name); > > #define dax_driver_register(driver) \ > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > > index ba0b4cd18a77..00c330ef437c 100644 > > --- a/drivers/dax/super.c > > +++ b/drivers/dax/super.c > > @@ -14,6 +14,7 @@ > > #include <linux/fs.h> > > #include <linux/cacheinfo.h> > > #include "dax-private.h" > > +#include "bus.h" > > > > /** > > * struct dax_device - anchor object for dax services > > @@ -111,6 +112,10 @@ struct dax_device *fs_dax_get_by_bdev(struct > > block_device *bdev, u64 *start_off, > > } > > EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev); > > > > +#endif /* CONFIG_BLOCK && CONFIG_FS_DAX */ > > + > > +#if IS_ENABLED(CONFIG_FS_DAX) > > + > > void fs_put_dax(struct dax_device *dax_dev, void *holder) > > { > > if (dax_dev && holder && > > @@ -119,7 +124,58 @@ void fs_put_dax(struct dax_device *dax_dev, void > > *holder) > > put_dax(dax_dev); > > } > > EXPORT_SYMBOL_GPL(fs_put_dax); > > -#endif /* CONFIG_BLOCK && CONFIG_FS_DAX */ > > + > > +/** > > + * fs_dax_get() - get ownership of a devdax via holder/holder_ops > > + * > > + * fs-dax file systems call this function to prepare to use a devdax > > device for > > + * fsdax. This is like fs_dax_get_by_bdev(), but the caller already has > > struct > > + * dev_dax (and there is no bdev). The holder makes this exclusive. > > + * > > + * @dax_dev: dev to be prepared for fs-dax usage > > + * @holder: filesystem or mapped device inside the dax_device > > + * @hops: operations for the inner holder > > + * > > + * Returns: 0 on success, <0 on failure > > + */ > > +int fs_dax_get(struct dax_device *dax_dev, void *holder, > > + const struct dax_holder_operations *hops) > > +{ > > + struct dev_dax *dev_dax; > > + struct dax_device_driver *dax_drv; > > + int id; > > + > > + id = dax_read_lock(); > > + if (!dax_dev || !dax_alive(dax_dev) || !igrab(&dax_dev->inode)) { > > + dax_read_unlock(id); > > + return -ENODEV; > > + } > > + dax_read_unlock(id); > > + > > + /* Verify the device is bound to fsdev_dax driver */ > > + dev_dax = dax_get_private(dax_dev); > > + if (!dev_dax || !dev_dax->dev.driver) { > > Don't you need to hold the dev_dax->dev device lock in order to check the > driver? > > DJ
Derp. Thanks for catching that Dave! I believe it's fixed for v8, which is probably coming early next week. John [snip]
