| Message ID | 20210604011844.1756145-3-ruansy.fnst@fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fsdax: introduce fs query to support reflink | expand |
On Thu, Jun 3, 2021 at 6:19 PM Shiyang Ruan <ruansy.fnst@fujitsu.com> wrote: > > To easily track filesystem from a pmem device, we introduce a holder for > dax_device structure, and also its operation. This holder is used to > remember who is using this dax_device: > - When it is the backend of a filesystem, the holder will be the > superblock of this filesystem. > - When this pmem device is one of the targets in a mapped device, the > holder will be this mapped device. In this case, the mapped device > has its own dax_device and it will follow the first rule. So that we > can finally track to the filesystem we needed. > > The holder and holder_ops will be set when filesystem is being mounted, > or an target device is being activated. > > Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> > --- > drivers/dax/super.c | 38 ++++++++++++++++++++++++++++++++++++++ > include/linux/dax.h | 10 ++++++++++ > 2 files changed, 48 insertions(+) > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > index 5fa6ae9dbc8b..d118e2a7dc70 100644 > --- a/drivers/dax/super.c > +++ b/drivers/dax/super.c > @@ -222,8 +222,10 @@ struct dax_device { > struct cdev cdev; > const char *host; > void *private; @private is likely too generic of a name now, it would be better to call this @parent. > + void *holder; This should probably be called holder_data, and this structure could use some kernel-doc to clarify what the fields mean. > unsigned long flags; > const struct dax_operations *ops; > + const struct dax_holder_operations *holder_ops; > }; > > static ssize_t write_cache_show(struct device *dev, > @@ -373,6 +375,24 @@ int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, > } > EXPORT_SYMBOL_GPL(dax_zero_page_range); > > +int dax_corrupted_range(struct dax_device *dax_dev, struct block_device *bdev, > + loff_t offset, size_t size, void *data) Why is @bdev an argument to this routine? The primary motivation for a 'struct dax_device' is to break the association with 'struct block_device'. The filesystem may know that the logical addresses associated with a given dax_dev alias with the logical addresses of a given bdev, but that knowledge need not leak into the API. > +{ > + int rc = -ENXIO; > + if (!dax_dev) > + return rc; > + > + if (dax_dev->holder) { > + rc = dax_dev->holder_ops->corrupted_range(dax_dev, bdev, offset, > + size, data); A bikeshed comment, but I do not like the name corrupted_range(), because "corrupted" implies a permanent state. The source of this notification is memory_failure() and that does not convey "permanent" vs "transient" it just reports "failure". So, to keep the naming consistent with the pgmap notification callback lets call this one "notify_failure". > + if (rc == -ENODEV) > + rc = -ENXIO; > + } else > + rc = -EOPNOTSUPP; > + return rc; > +} > +EXPORT_SYMBOL_GPL(dax_corrupted_range); dax_holder_notify_failure() makes it clearer that this is communicating a failure up the holder stack. > + > #ifdef CONFIG_ARCH_HAS_PMEM_API > void arch_wb_cache_pmem(void *addr, size_t size); > void dax_flush(struct dax_device *dax_dev, void *addr, size_t size) > @@ -624,6 +644,24 @@ void put_dax(struct dax_device *dax_dev) > } > EXPORT_SYMBOL_GPL(put_dax); > > +void dax_set_holder(struct dax_device *dax_dev, void *holder, > + const struct dax_holder_operations *ops) > +{ > + if (!dax_dev) > + return; > + dax_dev->holder = holder; > + dax_dev->holder_ops = ops; I think there needs to be some synchronization here, perhaps a global dax_dev_rwsem that is taken for read in the notification path and write when adding a holder to the chain. I also wonder if this should be an event that triggers a dax_dev stack to re-report any failure notifications. For example the pmem driver may have recorded a list of bad blocks at the beginning of time. Likely the filesystem or other holder would like to get that pre-existing list of failures at first registration. Have you given thought about how the filesystem is told about pre-existing badblocks? > +} > +EXPORT_SYMBOL_GPL(dax_set_holder); > + > +void *dax_get_holder(struct dax_device *dax_dev) > +{ > + if (!dax_dev) > + return NULL; > + return dax_dev->holder; > +} > +EXPORT_SYMBOL_GPL(dax_get_holder); Where is this used?
diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 5fa6ae9dbc8b..d118e2a7dc70 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -222,8 +222,10 @@ struct dax_device { struct cdev cdev; const char *host; void *private; + void *holder; unsigned long flags; const struct dax_operations *ops; + const struct dax_holder_operations *holder_ops; }; static ssize_t write_cache_show(struct device *dev, @@ -373,6 +375,24 @@ int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, } EXPORT_SYMBOL_GPL(dax_zero_page_range); +int dax_corrupted_range(struct dax_device *dax_dev, struct block_device *bdev, + loff_t offset, size_t size, void *data) +{ + int rc = -ENXIO; + if (!dax_dev) + return rc; + + if (dax_dev->holder) { + rc = dax_dev->holder_ops->corrupted_range(dax_dev, bdev, offset, + size, data); + if (rc == -ENODEV) + rc = -ENXIO; + } else + rc = -EOPNOTSUPP; + return rc; +} +EXPORT_SYMBOL_GPL(dax_corrupted_range); + #ifdef CONFIG_ARCH_HAS_PMEM_API void arch_wb_cache_pmem(void *addr, size_t size); void dax_flush(struct dax_device *dax_dev, void *addr, size_t size) @@ -624,6 +644,24 @@ void put_dax(struct dax_device *dax_dev) } EXPORT_SYMBOL_GPL(put_dax); +void dax_set_holder(struct dax_device *dax_dev, void *holder, + const struct dax_holder_operations *ops) +{ + if (!dax_dev) + return; + dax_dev->holder = holder; + dax_dev->holder_ops = ops; +} +EXPORT_SYMBOL_GPL(dax_set_holder); + +void *dax_get_holder(struct dax_device *dax_dev) +{ + if (!dax_dev) + return NULL; + return dax_dev->holder; +} +EXPORT_SYMBOL_GPL(dax_get_holder); + /** * dax_get_by_host() - temporary lookup mechanism for filesystem-dax * @host: alternate name for the device registered by a dax driver diff --git a/include/linux/dax.h b/include/linux/dax.h index b52f084aa643..1ce343a960ab 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -38,10 +38,18 @@ struct dax_operations { int (*zero_page_range)(struct dax_device *, pgoff_t, size_t); }; +struct dax_holder_operations { + int (*corrupted_range)(struct dax_device *, struct block_device *, + loff_t, size_t, void *); +}; + extern struct attribute_group dax_attribute_group; #if IS_ENABLED(CONFIG_DAX) struct dax_device *dax_get_by_host(const char *host); +void dax_set_holder(struct dax_device *dax_dev, void *holder, + const struct dax_holder_operations *ops); +void *dax_get_holder(struct dax_device *dax_dev); struct dax_device *alloc_dax(void *private, const char *host, const struct dax_operations *ops, unsigned long flags); void put_dax(struct dax_device *dax_dev); @@ -226,6 +234,8 @@ size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i); int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, size_t nr_pages); +int dax_corrupted_range(struct dax_device *dax_dev, struct block_device *bdev, + loff_t offset, size_t size, void *data); void dax_flush(struct dax_device *dax_dev, void *addr, size_t size); ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
To easily track filesystem from a pmem device, we introduce a holder for dax_device structure, and also its operation. This holder is used to remember who is using this dax_device: - When it is the backend of a filesystem, the holder will be the superblock of this filesystem. - When this pmem device is one of the targets in a mapped device, the holder will be this mapped device. In this case, the mapped device has its own dax_device and it will follow the first rule. So that we can finally track to the filesystem we needed. The holder and holder_ops will be set when filesystem is being mounted, or an target device is being activated. Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> --- drivers/dax/super.c | 38 ++++++++++++++++++++++++++++++++++++++ include/linux/dax.h | 10 ++++++++++ 2 files changed, 48 insertions(+)