Re: [PATCH v10 1/9] dax: Introduce holder for dax_device

2022-02-02 Thread Christoph Hellwig 
On Thu, Jan 27, 2022 at 08:40:50PM +0800, Shiyang Ruan wrote:
> +void dax_register_holder(struct dax_device *dax_dev, void *holder,
> + const struct dax_holder_operations *ops)
> +{
> + if (!dax_alive(dax_dev))
> + return;
> +
> + dax_dev->holder_data = holder;
> + dax_dev->holder_ops = ops;

This needs to return an error if there is another holder already.  And
some kind of locking to prevent concurrent registrations.

Also please add kerneldoc comments for the new exported functions.

> +void *dax_get_holder(struct dax_device *dax_dev)
> +{
> + if (!dax_alive(dax_dev))
> + return NULL;
> +
> + return dax_dev->holder_data;
> +}
> +EXPORT_SYMBOL_GPL(dax_get_holder);

get tends to imply getting a reference.  Maybe just dax_holder()?
That being said I can't see where we'd even want to use the holder
outside of this file.

Re: [PATCH v10 1/9] dax: Introduce holder for dax_device

2022-01-27 Thread kernel test robot 
Hi Shiyang,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linux/master]
[also build test WARNING on linus/master v5.17-rc1 next-20220127]
[cannot apply to xfs-linux/for-next hnaz-mm/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:
https://github.com/0day-ci/linux/commits/Shiyang-Ruan/fsdax-introduce-fs-query-to-support-reflink/20220127-204239
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
2c271fe77d52a0555161926c232cd5bc07178b39
config: powerpc-allnoconfig 
(https://download.01.org/0day-ci/archive/20220128/[email protected]/config)
compiler: powerpc-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
~/bin/make.cross
chmod +x ~/bin/make.cross
# 
https://github.com/0day-ci/linux/commit/57669ed05e93b37d995c5247eebe218ab2058c9a
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review 
Shiyang-Ruan/fsdax-introduce-fs-query-to-support-reflink/20220127-204239
git checkout 57669ed05e93b37d995c5247eebe218ab2058c9a
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross 
O=build_dir ARCH=powerpc SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot 

All warnings (new ones prefixed by >>):

   In file included from mm/filemap.c:15:
>> include/linux/dax.h:73:30: warning: 'struct dax_holder_operations' declared 
>> inside parameter list will not be visible outside of this definition or 
>> declaration
  73 | const struct dax_holder_operations *ops)
 |  ^


vim +73 include/linux/dax.h

48  
49  void dax_register_holder(struct dax_device *dax_dev, void *holder,
50  const struct dax_holder_operations *ops);
51  void dax_unregister_holder(struct dax_device *dax_dev);
52  void *dax_get_holder(struct dax_device *dax_dev);
53  void put_dax(struct dax_device *dax_dev);
54  void kill_dax(struct dax_device *dax_dev);
55  void dax_write_cache(struct dax_device *dax_dev, bool wc);
56  bool dax_write_cache_enabled(struct dax_device *dax_dev);
57  bool dax_synchronous(struct dax_device *dax_dev);
58  void set_dax_synchronous(struct dax_device *dax_dev);
59  /*
60   * Check if given mapping is supported by the file / underlying device.
61   */
62  static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
63   struct dax_device *dax_dev)
64  {
65  if (!(vma->vm_flags & VM_SYNC))
66  return true;
67  if (!IS_DAX(file_inode(vma->vm_file)))
68  return false;
69  return dax_synchronous(dax_dev);
70  }
71  #else
72  static inline void dax_register_holder(struct dax_device *dax_dev, void 
*holder,
  > 73  const struct dax_holder_operations *ops)
74  {
75  }
76  static inline void dax_unregister_holder(struct dax_device *dax_dev)
77  {
78  }
79  static inline void *dax_get_holder(struct dax_device *dax_dev)
80  {
81  return NULL;
82  }
83  static inline struct dax_device *alloc_dax(void *private,
84  const struct dax_operations *ops)
85  {
86  /*
87   * Callers should check IS_ENABLED(CONFIG_DAX) to know if this
88   * NULL is an error or expected.
89   */
90  return NULL;
91  }
92  static inline void put_dax(struct dax_device *dax_dev)
93  {
94  }
95  static inline void kill_dax(struct dax_device *dax_dev)
96  {
97  }
98  static inline void dax_write_cache(struct dax_device *dax_dev, bool wc)
99  {
   100  }
   101  static inline bool dax_write_cache_enabled(struct dax_device *dax_dev)
   102  {
   103  return false;
   104  }
   105  static inline bool dax_synchronous(struct dax_device *dax_dev)
   106  {
   107  return true;
   108  }
   109  static inline void set_dax_synchronous(struct dax_device *dax_dev)
   110  {
   111  }
   112  static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
   113  struct dax_device *dax_dev)
   114  {
   115  return !(vma->vm_flags & VM_SYNC);
   116  }
   117  #endif
   118  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

Re: [PATCH v10 1/9] dax: Introduce holder for dax_device

2022-01-27 Thread kernel test robot 
Hi Shiyang,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linux/master]
[also build test WARNING on linus/master v5.17-rc1 next-20220127]
[cannot apply to xfs-linux/for-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:
https://github.com/0day-ci/linux/commits/Shiyang-Ruan/fsdax-introduce-fs-query-to-support-reflink/20220127-204239
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
2c271fe77d52a0555161926c232cd5bc07178b39
config: arm-imx_v4_v5_defconfig 
(https://download.01.org/0day-ci/archive/20220128/[email protected]/config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 
f32dccb9a43b02ce4e540d6ba5dbbdb188f2dc7d)
reproduce (this is a W=1 build):
wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
~/bin/make.cross
chmod +x ~/bin/make.cross
# install arm cross compiling tool for clang build
# apt-get install binutils-arm-linux-gnueabi
# 
https://github.com/0day-ci/linux/commit/57669ed05e93b37d995c5247eebe218ab2058c9a
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review 
Shiyang-Ruan/fsdax-introduce-fs-query-to-support-reflink/20220127-204239
git checkout 57669ed05e93b37d995c5247eebe218ab2058c9a
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 
O=build_dir ARCH=arm SHELL=/bin/bash fs/iomap/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot 

All warnings (new ones prefixed by >>):

   In file included from fs/iomap/buffered-io.c:13:
>> include/linux/dax.h:73:16: warning: declaration of 'struct 
>> dax_holder_operations' will not be visible outside of this function 
>> [-Wvisibility]
   const struct dax_holder_operations *ops)
^
   1 warning generated.


vim +73 include/linux/dax.h

48  
49  void dax_register_holder(struct dax_device *dax_dev, void *holder,
50  const struct dax_holder_operations *ops);
51  void dax_unregister_holder(struct dax_device *dax_dev);
52  void *dax_get_holder(struct dax_device *dax_dev);
53  void put_dax(struct dax_device *dax_dev);
54  void kill_dax(struct dax_device *dax_dev);
55  void dax_write_cache(struct dax_device *dax_dev, bool wc);
56  bool dax_write_cache_enabled(struct dax_device *dax_dev);
57  bool dax_synchronous(struct dax_device *dax_dev);
58  void set_dax_synchronous(struct dax_device *dax_dev);
59  /*
60   * Check if given mapping is supported by the file / underlying device.
61   */
62  static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
63   struct dax_device *dax_dev)
64  {
65  if (!(vma->vm_flags & VM_SYNC))
66  return true;
67  if (!IS_DAX(file_inode(vma->vm_file)))
68  return false;
69  return dax_synchronous(dax_dev);
70  }
71  #else
72  static inline void dax_register_holder(struct dax_device *dax_dev, void 
*holder,
  > 73  const struct dax_holder_operations *ops)
74  {
75  }
76  static inline void dax_unregister_holder(struct dax_device *dax_dev)
77  {
78  }
79  static inline void *dax_get_holder(struct dax_device *dax_dev)
80  {
81  return NULL;
82  }
83  static inline struct dax_device *alloc_dax(void *private,
84  const struct dax_operations *ops)
85  {
86  /*
87   * Callers should check IS_ENABLED(CONFIG_DAX) to know if this
88   * NULL is an error or expected.
89   */
90  return NULL;
91  }
92  static inline void put_dax(struct dax_device *dax_dev)
93  {
94  }
95  static inline void kill_dax(struct dax_device *dax_dev)
96  {
97  }
98  static inline void dax_write_cache(struct dax_device *dax_dev, bool wc)
99  {
   100  }
   101  static inline bool dax_write_cache_enabled(struct dax_device *dax_dev)
   102  {
   103  return false;
   104  }
   105  static inline bool dax_synchronous(struct dax_device *dax_dev)
   106  {
   107  return true;
   108  }
   109  static inline void set_dax_synchronous(struct dax_device *dax_dev)
   110  {
   111  }
   112  static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
   113  struct dax_device *dax_dev)
   114  {
   115  return !(vma->vm_flags & VM_SYNC);
   116  }
   117  #endif
   118  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.or

[PATCH v10 1/9] dax: Introduce holder for dax_device

2022-01-27 Thread Shiyang Ruan 
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
   instance 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 
---
 drivers/dax/super.c | 62 +
 include/linux/dax.h | 29 +
 2 files changed, 91 insertions(+)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e3029389d809..8e2733b78437 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -21,6 +21,9 @@
  * @cdev: optional character interface for "device dax"
  * @private: dax driver private data
  * @flags: state and boolean properties
+ * @ops: operations for dax_device
+ * @holder_data: holder of a dax_device: could be filesystem or mapped device
+ * @holder_ops: operations for the inner holder
  */
 struct dax_device {
struct inode inode;
@@ -28,6 +31,8 @@ struct dax_device {
void *private;
unsigned long flags;
const struct dax_operations *ops;
+   void *holder_data;
+   const struct dax_holder_operations *holder_ops;
 };
 
 static dev_t dax_devt;
@@ -193,6 +198,29 @@ int dax_zero_page_range(struct dax_device *dax_dev, 
pgoff_t pgoff,
 }
 EXPORT_SYMBOL_GPL(dax_zero_page_range);
 
+int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off,
+ u64 len, int mf_flags)
+{
+   int rc, id;
+
+   id = dax_read_lock();
+   if (!dax_alive(dax_dev)) {
+   rc = -ENXIO;
+   goto out;
+   }
+
+   if (!dax_dev->holder_ops) {
+   rc = -EOPNOTSUPP;
+   goto out;
+   }
+
+   rc = dax_dev->holder_ops->notify_failure(dax_dev, off, len, mf_flags);
+out:
+   dax_read_unlock(id);
+   return rc;
+}
+EXPORT_SYMBOL_GPL(dax_holder_notify_failure);
+
 #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)
@@ -268,6 +296,10 @@ void kill_dax(struct dax_device *dax_dev)
 
clear_bit(DAXDEV_ALIVE, &dax_dev->flags);
synchronize_srcu(&dax_srcu);
+
+   /* clear holder data */
+   dax_dev->holder_ops = NULL;
+   dax_dev->holder_data = NULL;
 }
 EXPORT_SYMBOL_GPL(kill_dax);
 
@@ -409,6 +441,36 @@ void put_dax(struct dax_device *dax_dev)
 }
 EXPORT_SYMBOL_GPL(put_dax);
 
+void dax_register_holder(struct dax_device *dax_dev, void *holder,
+   const struct dax_holder_operations *ops)
+{
+   if (!dax_alive(dax_dev))
+   return;
+
+   dax_dev->holder_data = holder;
+   dax_dev->holder_ops = ops;
+}
+EXPORT_SYMBOL_GPL(dax_register_holder);
+
+void dax_unregister_holder(struct dax_device *dax_dev)
+{
+   if (!dax_alive(dax_dev))
+   return;
+
+   dax_dev->holder_data = NULL;
+   dax_dev->holder_ops = NULL;
+}
+EXPORT_SYMBOL_GPL(dax_unregister_holder);
+
+void *dax_get_holder(struct dax_device *dax_dev)
+{
+   if (!dax_alive(dax_dev))
+   return NULL;
+
+   return dax_dev->holder_data;
+}
+EXPORT_SYMBOL_GPL(dax_get_holder);
+
 /**
  * inode_dax: convert a public inode into its dax_dev
  * @inode: An inode with i_cdev pointing to a dax_dev
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 9fc5f99a0ae2..96cfc63b12fd 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -34,6 +34,22 @@ struct dax_operations {
 
 #if IS_ENABLED(CONFIG_DAX)
 struct dax_device *alloc_dax(void *private, const struct dax_operations *ops);
+struct dax_holder_operations {
+   /*
+* notify_failure - notify memory failure into inner holder device
+* @dax_dev: the dax device which contains the holder
+* @offset: offset on this dax device where memory failure occurs
+* @len: length of this memory failure event
+* @flags: action flags for memory failure handler
+*/
+   int (*notify_failure)(struct dax_device *dax_dev, u64 offset,
+   u64 len, int mf_flags);
+};
+
+void dax_register_holder(struct dax_device *dax_dev, void *holder,
+   const struct dax_holder_operations *ops);
+void dax_unregister_holder(struct dax_device *dax_dev);
+void *dax_get_holder(struct dax_device *dax_dev);
 void put_dax(struct dax_device *dax_dev);
 void kill_dax(struct dax_device *dax_dev);
 void dax_write_cache(struct dax_device *dax_dev, bool wc);
@@ -53,6 +69,17 @@ static inline bool daxdev_mapping_supported(struct 
vm_area_struct *vma,