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[PATCH 0/6] introduce DAX tracepoint support

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  [PATCH 0/6] introduce DAX tracepoint support Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-11-23 19:50 +0100
    [PATCH 5/6] dax: add tracepoints to dax_pmd_load_hole() Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-11-23 19:50 +0100
      Re: [PATCH 5/6] dax: add tracepoints to dax_pmd_load_hole() Jan Kara <jack@suse.cz> - 2016-11-24 10:40 +0100
    [PATCH 6/6] dax: add tracepoints to dax_pmd_insert_mapping() Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-11-23 19:50 +0100
      Re: [PATCH 6/6] dax: add tracepoints to dax_pmd_insert_mapping() Jan Kara <jack@suse.cz> - 2016-11-24 10:30 +0100
    [PATCH 4/6] dax: update MAINTAINERS entries for FS DAX Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-11-23 19:50 +0100
    [PATCH 2/6] dax: remove leading space from labels Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-11-23 19:50 +0100
      Re: [PATCH 2/6] dax: remove leading space from labels Jan Kara <jack@suse.cz> - 2016-11-24 10:20 +0100
        Re: [PATCH 2/6] dax: remove leading space from labels Dan Williams <dan.j.williams@intel.com> - 2016-11-24 20:50 +0100
    [PATCH 1/6] dax: fix build breakage with ext4, dax and !iomap Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-11-23 19:50 +0100
      Re: [PATCH 1/6] dax: fix build breakage with ext4, dax and !iomap Jan Kara <jack@suse.cz> - 2016-11-24 10:20 +0100

#1528684 — [PATCH 0/6] introduce DAX tracepoint support

Tracepoints are the standard way to capture debugging and tracing
information in many parts of the kernel, including the XFS and ext4
filesystems.  This series creates a tracepoint header for FS DAX and add
the first few DAX tracepoints to the PMD fault handler.  This allows the
tracing for DAX to be done in the same way as the filesystem tracing so
that developers can look at them together and get a coherent idea of what
the system is doing.                                                            
                                                                                
I do intend to add tracepoints to the normal 4k DAX fault path and to the       
DAX I/O path, but I wanted to get feedback on the PMD tracepoints before I      
went any further.                                                               
                                                                                
This series is based on Jan Kara's "dax: Clear dirty bits after flushing        
caches" series:                                                                 
                                                                                
https://lists.01.org/pipermail/linux-nvdimm/2016-November/007864.html           
                                                                                
I've pushed a git tree with this work here:                                     
                                                                                
https://git.kernel.org/cgit/linux/kernel/git/zwisler/linux.git/log/?h=dax_tracepoints

Ross Zwisler (6):
  dax: fix build breakage with ext4, dax and !iomap
  dax: remove leading space from labels
  dax: add tracepoint infrastructure, PMD tracing
  dax: update MAINTAINERS entries for FS DAX
  dax: add tracepoints to dax_pmd_load_hole()
  dax: add tracepoints to dax_pmd_insert_mapping()

 MAINTAINERS                   |   4 +-
 fs/Kconfig                    |   1 +
 fs/dax.c                      |  78 ++++++++++++++----------
 fs/ext2/Kconfig               |   1 -
 include/linux/mm.h            |  14 +++++
 include/linux/pfn_t.h         |   6 ++
 include/trace/events/fs_dax.h | 135 ++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 206 insertions(+), 33 deletions(-)
 create mode 100644 include/trace/events/fs_dax.h

-- 
2.7.4

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#1528685 — [PATCH 5/6] dax: add tracepoints to dax_pmd_load_hole()

Add tracepoints to dax_pmd_load_hole(), following the same logging
conventions as the tracepoints in dax_iomap_pmd_fault().

Here is an example PMD fault showing the new tracepoints:

read_big-1393  [007] ....    32.133809: dax_pmd_fault: shared mapping read
address 0x10400000 vm_start 0x10200000 vm_end 0x10600000 pgoff 0x200
max_pgoff 0x1400

read_big-1393  [007] ....    32.134067: dax_pmd_load_hole: shared mapping
read address 0x10400000 zero_page ffffea0002b98000 radix_entry 0x1e

read_big-1393  [007] ....    32.134069: dax_pmd_fault_done: shared mapping
read address 0x10400000 vm_start 0x10200000 vm_end 0x10600000 pgoff 0x200
max_pgoff 0x1400 NOPAGE

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/dax.c                      | 13 +++++++++----
 include/trace/events/fs_dax.h | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 1aa7616..2824414 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1269,32 +1269,37 @@ static int dax_pmd_load_hole(struct vm_area_struct *vma, pmd_t *pmd,
 	struct address_space *mapping = vma->vm_file->f_mapping;
 	unsigned long pmd_addr = address & PMD_MASK;
 	struct page *zero_page;
+	void *ret = NULL;
 	spinlock_t *ptl;
 	pmd_t pmd_entry;
-	void *ret;
 
 	zero_page = mm_get_huge_zero_page(vma->vm_mm);
 
 	if (unlikely(!zero_page))
-		return VM_FAULT_FALLBACK;
+		goto fallback;
 
 	ret = dax_insert_mapping_entry(mapping, vmf, *entryp, 0,
 			RADIX_DAX_PMD | RADIX_DAX_HZP);
 	if (IS_ERR(ret))
-		return VM_FAULT_FALLBACK;
+		goto fallback;
 	*entryp = ret;
 
 	ptl = pmd_lock(vma->vm_mm, pmd);
 	if (!pmd_none(*pmd)) {
 		spin_unlock(ptl);
-		return VM_FAULT_FALLBACK;
+		goto fallback;
 	}
 
 	pmd_entry = mk_pmd(zero_page, vma->vm_page_prot);
 	pmd_entry = pmd_mkhuge(pmd_entry);
 	set_pmd_at(vma->vm_mm, pmd_addr, pmd, pmd_entry);
 	spin_unlock(ptl);
+	trace_dax_pmd_load_hole(vma, address, zero_page, ret);
 	return VM_FAULT_NOPAGE;
+
+fallback:
+	trace_dax_pmd_load_hole_fallback(vma, address, zero_page, ret);
+	return VM_FAULT_FALLBACK;
 }
 
 int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
index f9ed4eb..8814b1a 100644
--- a/include/trace/events/fs_dax.h
+++ b/include/trace/events/fs_dax.h
@@ -54,6 +54,38 @@ DEFINE_EVENT(dax_pmd_fault_class, name, \
 DEFINE_PMD_FAULT_EVENT(dax_pmd_fault);
 DEFINE_PMD_FAULT_EVENT(dax_pmd_fault_done);
 
+DECLARE_EVENT_CLASS(dax_pmd_load_hole_class,
+	TP_PROTO(struct vm_area_struct *vma, unsigned long address,
+		struct page *zero_page, void *radix_entry),
+	TP_ARGS(vma, address, zero_page, radix_entry),
+	TP_STRUCT__entry(
+		__field(unsigned long, vm_flags)
+		__field(unsigned long, address)
+		__field(struct page *, zero_page)
+		__field(void *, radix_entry)
+	),
+	TP_fast_assign(
+		__entry->vm_flags = vma->vm_flags;
+		__entry->address = address;
+		__entry->zero_page = zero_page;
+		__entry->radix_entry = radix_entry;
+	),
+	TP_printk("%s mapping read address %#lx zero_page %p radix_entry %#lx",
+		__entry->vm_flags & VM_SHARED ? "shared" : "private",
+		__entry->address,
+		__entry->zero_page,
+		(unsigned long)__entry->radix_entry
+	)
+)
+
+#define DEFINE_PMD_LOAD_HOLE_EVENT(name) \
+DEFINE_EVENT(dax_pmd_load_hole_class, name, \
+	TP_PROTO(struct vm_area_struct *vma, unsigned long address, \
+		struct page *zero_page, void *radix_entry), \
+	TP_ARGS(vma, address, zero_page, radix_entry))
+
+DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole);
+DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole_fallback);
 
 #endif /* _TRACE_FS_DAX_H */
 
-- 
2.7.4

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#1529102 — Re: [PATCH 5/6] dax: add tracepoints to dax_pmd_load_hole()

On Wed 23-11-16 11:44:21, Ross Zwisler wrote:
> Add tracepoints to dax_pmd_load_hole(), following the same logging
> conventions as the tracepoints in dax_iomap_pmd_fault().
> 
> Here is an example PMD fault showing the new tracepoints:
> 
> read_big-1393  [007] ....    32.133809: dax_pmd_fault: shared mapping read
> address 0x10400000 vm_start 0x10200000 vm_end 0x10600000 pgoff 0x200
> max_pgoff 0x1400
> 
> read_big-1393  [007] ....    32.134067: dax_pmd_load_hole: shared mapping
> read address 0x10400000 zero_page ffffea0002b98000 radix_entry 0x1e
> 
> read_big-1393  [007] ....    32.134069: dax_pmd_fault_done: shared mapping
> read address 0x10400000 vm_start 0x10200000 vm_end 0x10600000 pgoff 0x200
> max_pgoff 0x1400 NOPAGE
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza
> ---
>  fs/dax.c                      | 13 +++++++++----
>  include/trace/events/fs_dax.h | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 1aa7616..2824414 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1269,32 +1269,37 @@ static int dax_pmd_load_hole(struct vm_area_struct *vma, pmd_t *pmd,
>  	struct address_space *mapping = vma->vm_file->f_mapping;
>  	unsigned long pmd_addr = address & PMD_MASK;
>  	struct page *zero_page;
> +	void *ret = NULL;
>  	spinlock_t *ptl;
>  	pmd_t pmd_entry;
> -	void *ret;
>  
>  	zero_page = mm_get_huge_zero_page(vma->vm_mm);
>  
>  	if (unlikely(!zero_page))
> -		return VM_FAULT_FALLBACK;
> +		goto fallback;
>  
>  	ret = dax_insert_mapping_entry(mapping, vmf, *entryp, 0,
>  			RADIX_DAX_PMD | RADIX_DAX_HZP);
>  	if (IS_ERR(ret))
> -		return VM_FAULT_FALLBACK;
> +		goto fallback;
>  	*entryp = ret;
>  
>  	ptl = pmd_lock(vma->vm_mm, pmd);
>  	if (!pmd_none(*pmd)) {
>  		spin_unlock(ptl);
> -		return VM_FAULT_FALLBACK;
> +		goto fallback;
>  	}
>  
>  	pmd_entry = mk_pmd(zero_page, vma->vm_page_prot);
>  	pmd_entry = pmd_mkhuge(pmd_entry);
>  	set_pmd_at(vma->vm_mm, pmd_addr, pmd, pmd_entry);
>  	spin_unlock(ptl);
> +	trace_dax_pmd_load_hole(vma, address, zero_page, ret);
>  	return VM_FAULT_NOPAGE;
> +
> +fallback:
> +	trace_dax_pmd_load_hole_fallback(vma, address, zero_page, ret);
> +	return VM_FAULT_FALLBACK;
>  }
>  
>  int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
> diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
> index f9ed4eb..8814b1a 100644
> --- a/include/trace/events/fs_dax.h
> +++ b/include/trace/events/fs_dax.h
> @@ -54,6 +54,38 @@ DEFINE_EVENT(dax_pmd_fault_class, name, \
>  DEFINE_PMD_FAULT_EVENT(dax_pmd_fault);
>  DEFINE_PMD_FAULT_EVENT(dax_pmd_fault_done);
>  
> +DECLARE_EVENT_CLASS(dax_pmd_load_hole_class,
> +	TP_PROTO(struct vm_area_struct *vma, unsigned long address,
> +		struct page *zero_page, void *radix_entry),
> +	TP_ARGS(vma, address, zero_page, radix_entry),
> +	TP_STRUCT__entry(
> +		__field(unsigned long, vm_flags)
> +		__field(unsigned long, address)
> +		__field(struct page *, zero_page)
> +		__field(void *, radix_entry)
> +	),
> +	TP_fast_assign(
> +		__entry->vm_flags = vma->vm_flags;
> +		__entry->address = address;
> +		__entry->zero_page = zero_page;
> +		__entry->radix_entry = radix_entry;
> +	),
> +	TP_printk("%s mapping read address %#lx zero_page %p radix_entry %#lx",
> +		__entry->vm_flags & VM_SHARED ? "shared" : "private",
> +		__entry->address,
> +		__entry->zero_page,
> +		(unsigned long)__entry->radix_entry
> +	)
> +)
> +
> +#define DEFINE_PMD_LOAD_HOLE_EVENT(name) \
> +DEFINE_EVENT(dax_pmd_load_hole_class, name, \
> +	TP_PROTO(struct vm_area_struct *vma, unsigned long address, \
> +		struct page *zero_page, void *radix_entry), \
> +	TP_ARGS(vma, address, zero_page, radix_entry))
> +
> +DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole);
> +DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole_fallback);
>  
>  #endif /* _TRACE_FS_DAX_H */
>  
> -- 
> 2.7.4
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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#1528686 — [PATCH 6/6] dax: add tracepoints to dax_pmd_insert_mapping()

Add tracepoints to dax_pmd_insert_mapping(), following the same logging
conventions as the tracepoints in dax_iomap_pmd_fault().

Here is an example PMD fault showing the new tracepoints:

big-1544  [006] ....    48.153479: dax_pmd_fault: shared mapping write
address 0x10505000 vm_start 0x10200000 vm_end 0x10700000 pgoff 0x200
max_pgoff 0x1400

big-1544  [006] ....    48.155230: dax_pmd_insert_mapping: shared mapping
write address 0x10505000 length 0x200000 pfn 0x100600 DEV|MAP radix_entry
0xc000e

big-1544  [006] ....    48.155266: dax_pmd_fault_done: shared mapping write
address 0x10505000 vm_start 0x10200000 vm_end 0x10700000 pgoff 0x200
max_pgoff 0x1400 NOPAGE

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/dax.c                      | 10 +++++++---
 include/linux/pfn_t.h         |  6 ++++++
 include/trace/events/fs_dax.h | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 2824414..d6ba4a3 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1236,10 +1236,10 @@ static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
 		.size = PMD_SIZE,
 	};
 	long length = dax_map_atomic(bdev, &dax);
-	void *ret;
+	void *ret = NULL;
 
 	if (length < 0) /* dax_map_atomic() failed */
-		return VM_FAULT_FALLBACK;
+		goto fallback;
 	if (length < PMD_SIZE)
 		goto unmap_fallback;
 	if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)
@@ -1252,13 +1252,17 @@ static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
 	ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector,
 			RADIX_DAX_PMD);
 	if (IS_ERR(ret))
-		return VM_FAULT_FALLBACK;
+		goto fallback;
 	*entryp = ret;
 
+	trace_dax_pmd_insert_mapping(vma, address, write, length, dax.pfn, ret);
 	return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
 
 unmap_fallback:
 	dax_unmap_atomic(bdev, &dax);
+fallback:
+	trace_dax_pmd_insert_mapping_fallback(vma, address, write, length,
+			dax.pfn, ret);
 	return VM_FAULT_FALLBACK;
 }
 
diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
index a3d90b9..033fc7b 100644
--- a/include/linux/pfn_t.h
+++ b/include/linux/pfn_t.h
@@ -15,6 +15,12 @@
 #define PFN_DEV (1ULL << (BITS_PER_LONG_LONG - 3))
 #define PFN_MAP (1ULL << (BITS_PER_LONG_LONG - 4))
 
+#define PFN_FLAGS_TRACE \
+	{ PFN_SG_CHAIN,	"SG_CHAIN" }, \
+	{ PFN_SG_LAST,	"SG_LAST" }, \
+	{ PFN_DEV,	"DEV" }, \
+	{ PFN_MAP,	"MAP" }
+
 static inline pfn_t __pfn_to_pfn_t(unsigned long pfn, u64 flags)
 {
 	pfn_t pfn_t = { .val = pfn | (flags & PFN_FLAGS_MASK), };
diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
index 8814b1a..a03f820 100644
--- a/include/trace/events/fs_dax.h
+++ b/include/trace/events/fs_dax.h
@@ -87,6 +87,48 @@ DEFINE_EVENT(dax_pmd_load_hole_class, name, \
 DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole);
 DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole_fallback);
 
+DECLARE_EVENT_CLASS(dax_pmd_insert_mapping_class,
+	TP_PROTO(struct vm_area_struct *vma, unsigned long address, int write,
+		long length, pfn_t pfn, void *radix_entry),
+	TP_ARGS(vma, address, write, length, pfn, radix_entry),
+	TP_STRUCT__entry(
+		__field(unsigned long, vm_flags)
+		__field(unsigned long, address)
+		__field(int, write)
+		__field(long, length)
+		__field(u64, pfn_val)
+		__field(void *, radix_entry)
+	),
+	TP_fast_assign(
+		__entry->vm_flags = vma->vm_flags;
+		__entry->address = address;
+		__entry->write = write;
+		__entry->length = length;
+		__entry->pfn_val = pfn.val;
+		__entry->radix_entry = radix_entry;
+	),
+	TP_printk("%s mapping %s address %#lx length %#lx pfn %#llx %s"
+		" radix_entry %#lx",
+		__entry->vm_flags & VM_SHARED ? "shared" : "private",
+		__entry->write ? "write" : "read",
+		__entry->address,
+		__entry->length,
+		__entry->pfn_val & ~PFN_FLAGS_MASK,
+		__print_flags(__entry->pfn_val & PFN_FLAGS_MASK, "|",
+			PFN_FLAGS_TRACE),
+		(unsigned long)__entry->radix_entry
+	)
+)
+
+#define DEFINE_PMD_INSERT_MAPPING_EVENT(name) \
+DEFINE_EVENT(dax_pmd_insert_mapping_class, name, \
+	TP_PROTO(struct vm_area_struct *vma, unsigned long address, \
+		int write, long length, pfn_t pfn, void *radix_entry), \
+	TP_ARGS(vma, address, write, length, pfn, radix_entry))
+
+DEFINE_PMD_INSERT_MAPPING_EVENT(dax_pmd_insert_mapping);
+DEFINE_PMD_INSERT_MAPPING_EVENT(dax_pmd_insert_mapping_fallback);
+
 #endif /* _TRACE_FS_DAX_H */
 
 /* This part must be outside protection */
-- 
2.7.4

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#1529095 — Re: [PATCH 6/6] dax: add tracepoints to dax_pmd_insert_mapping()

On Wed 23-11-16 11:44:22, Ross Zwisler wrote:
> Add tracepoints to dax_pmd_insert_mapping(), following the same logging
> conventions as the tracepoints in dax_iomap_pmd_fault().
> 
> Here is an example PMD fault showing the new tracepoints:
> 
> big-1544  [006] ....    48.153479: dax_pmd_fault: shared mapping write
> address 0x10505000 vm_start 0x10200000 vm_end 0x10700000 pgoff 0x200
> max_pgoff 0x1400
> 
> big-1544  [006] ....    48.155230: dax_pmd_insert_mapping: shared mapping
> write address 0x10505000 length 0x200000 pfn 0x100600 DEV|MAP radix_entry
> 0xc000e
> 
> big-1544  [006] ....    48.155266: dax_pmd_fault_done: shared mapping write
> address 0x10505000 vm_start 0x10200000 vm_end 0x10700000 pgoff 0x200
> max_pgoff 0x1400 NOPAGE
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/dax.c                      | 10 +++++++---
>  include/linux/pfn_t.h         |  6 ++++++
>  include/trace/events/fs_dax.h | 42 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 55 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 2824414..d6ba4a3 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1236,10 +1236,10 @@ static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
>  		.size = PMD_SIZE,
>  	};
>  	long length = dax_map_atomic(bdev, &dax);
> -	void *ret;
> +	void *ret = NULL;
>  
>  	if (length < 0) /* dax_map_atomic() failed */
> -		return VM_FAULT_FALLBACK;
> +		goto fallback;
>  	if (length < PMD_SIZE)
>  		goto unmap_fallback;
>  	if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)
> @@ -1252,13 +1252,17 @@ static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
>  	ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector,
>  			RADIX_DAX_PMD);
>  	if (IS_ERR(ret))
> -		return VM_FAULT_FALLBACK;
> +		goto fallback;
>  	*entryp = ret;
>  
> +	trace_dax_pmd_insert_mapping(vma, address, write, length, dax.pfn, ret);
>  	return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
>  
>  unmap_fallback:
>  	dax_unmap_atomic(bdev, &dax);
> +fallback:
> +	trace_dax_pmd_insert_mapping_fallback(vma, address, write, length,
> +			dax.pfn, ret);
>  	return VM_FAULT_FALLBACK;
>  }
>  
> diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
> index a3d90b9..033fc7b 100644
> --- a/include/linux/pfn_t.h
> +++ b/include/linux/pfn_t.h
> @@ -15,6 +15,12 @@
>  #define PFN_DEV (1ULL << (BITS_PER_LONG_LONG - 3))
>  #define PFN_MAP (1ULL << (BITS_PER_LONG_LONG - 4))
>  
> +#define PFN_FLAGS_TRACE \
> +	{ PFN_SG_CHAIN,	"SG_CHAIN" }, \
> +	{ PFN_SG_LAST,	"SG_LAST" }, \
> +	{ PFN_DEV,	"DEV" }, \
> +	{ PFN_MAP,	"MAP" }
> +
>  static inline pfn_t __pfn_to_pfn_t(unsigned long pfn, u64 flags)
>  {
>  	pfn_t pfn_t = { .val = pfn | (flags & PFN_FLAGS_MASK), };
> diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
> index 8814b1a..a03f820 100644
> --- a/include/trace/events/fs_dax.h
> +++ b/include/trace/events/fs_dax.h
> @@ -87,6 +87,48 @@ DEFINE_EVENT(dax_pmd_load_hole_class, name, \
>  DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole);
>  DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole_fallback);
>  
> +DECLARE_EVENT_CLASS(dax_pmd_insert_mapping_class,
> +	TP_PROTO(struct vm_area_struct *vma, unsigned long address, int write,
> +		long length, pfn_t pfn, void *radix_entry),
> +	TP_ARGS(vma, address, write, length, pfn, radix_entry),
> +	TP_STRUCT__entry(
> +		__field(unsigned long, vm_flags)
> +		__field(unsigned long, address)
> +		__field(int, write)
> +		__field(long, length)
> +		__field(u64, pfn_val)
> +		__field(void *, radix_entry)
> +	),
> +	TP_fast_assign(
> +		__entry->vm_flags = vma->vm_flags;
> +		__entry->address = address;
> +		__entry->write = write;
> +		__entry->length = length;
> +		__entry->pfn_val = pfn.val;
> +		__entry->radix_entry = radix_entry;
> +	),
> +	TP_printk("%s mapping %s address %#lx length %#lx pfn %#llx %s"
> +		" radix_entry %#lx",
> +		__entry->vm_flags & VM_SHARED ? "shared" : "private",
> +		__entry->write ? "write" : "read",
> +		__entry->address,
> +		__entry->length,
> +		__entry->pfn_val & ~PFN_FLAGS_MASK,
> +		__print_flags(__entry->pfn_val & PFN_FLAGS_MASK, "|",
> +			PFN_FLAGS_TRACE),
> +		(unsigned long)__entry->radix_entry
> +	)
> +)
> +
> +#define DEFINE_PMD_INSERT_MAPPING_EVENT(name) \
> +DEFINE_EVENT(dax_pmd_insert_mapping_class, name, \
> +	TP_PROTO(struct vm_area_struct *vma, unsigned long address, \
> +		int write, long length, pfn_t pfn, void *radix_entry), \
> +	TP_ARGS(vma, address, write, length, pfn, radix_entry))
> +
> +DEFINE_PMD_INSERT_MAPPING_EVENT(dax_pmd_insert_mapping);
> +DEFINE_PMD_INSERT_MAPPING_EVENT(dax_pmd_insert_mapping_fallback);
> +
>  #endif /* _TRACE_FS_DAX_H */
>  
>  /* This part must be outside protection */
> -- 
> 2.7.4
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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#1528687 — [PATCH 4/6] dax: update MAINTAINERS entries for FS DAX

Add the new include/trace/events/fs_dax.h tracepoint header, update
Matthew's email address and add myself as a maintainer for filesystem DAX.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Matthew Wilcox <mawilcox@microsoft.com>
---
 MAINTAINERS | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 2a58eea..8fef4bf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3855,10 +3855,12 @@ S:	Maintained
 F:	drivers/i2c/busses/i2c-diolan-u2c.c
 
 DIRECT ACCESS (DAX)
-M:	Matthew Wilcox <willy@linux.intel.com>
+M:	Matthew Wilcox <mawilcox@microsoft.com>
+M:	Ross Zwisler <ross.zwisler@linux.intel.com>
 L:	linux-fsdevel@vger.kernel.org
 S:	Supported
 F:	fs/dax.c
+F:	include/trace/events/fs_dax.h
 
 DIRECTORY NOTIFICATION (DNOTIFY)
 M:	Eric Paris <eparis@parisplace.org>
-- 
2.7.4

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#1528691 — [PATCH 2/6] dax: remove leading space from labels

No functional change.

As of this commit:

commit 218dd85887da (".gitattributes: set git diff driver for C source code
files")

git-diff and git-format-patch both generate diffs whose hunks are correctly
prefixed by function names instead of labels, even if those labels aren't
indented with spaces.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/dax.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index d8fe3eb..cc8a069 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -422,7 +422,7 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
 		return page;
 	}
 	entry = lock_slot(mapping, slot);
- out_unlock:
+out_unlock:
 	spin_unlock_irq(&mapping->tree_lock);
 	return entry;
 }
@@ -557,7 +557,7 @@ static int dax_load_hole(struct address_space *mapping, void **entry,
 				   vmf->gfp_mask | __GFP_ZERO);
 	if (!page)
 		return VM_FAULT_OOM;
- out:
+out:
 	vmf->page = page;
 	ret = finish_fault(vmf);
 	vmf->page = NULL;
@@ -659,7 +659,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
 	}
 	if (vmf->flags & FAULT_FLAG_WRITE)
 		radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
- unlock:
+unlock:
 	spin_unlock_irq(&mapping->tree_lock);
 	if (hole_fill) {
 		radix_tree_preload_end();
@@ -812,12 +812,12 @@ static int dax_writeback_one(struct block_device *bdev,
 	spin_lock_irq(&mapping->tree_lock);
 	radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
 	spin_unlock_irq(&mapping->tree_lock);
- unmap:
+unmap:
 	dax_unmap_atomic(bdev, &dax);
 	put_locked_mapping_entry(mapping, index, entry);
 	return ret;
 
- put_unlocked:
+put_unlocked:
 	put_unlocked_mapping_entry(mapping, index, entry2);
 	spin_unlock_irq(&mapping->tree_lock);
 	return ret;
@@ -1193,11 +1193,11 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 		break;
 	}
 
- error_unlock_entry:
+error_unlock_entry:
 	vmf_ret = dax_fault_return(error) | major;
- unlock_entry:
+unlock_entry:
 	put_locked_mapping_entry(mapping, vmf->pgoff, entry);
- finish_iomap:
+finish_iomap:
 	if (ops->iomap_end) {
 		int copied = PAGE_SIZE;
 
@@ -1254,7 +1254,7 @@ static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
 
 	return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
 
- unmap_fallback:
+unmap_fallback:
 	dax_unmap_atomic(bdev, &dax);
 	return VM_FAULT_FALLBACK;
 }
@@ -1378,9 +1378,9 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		break;
 	}
 
- unlock_entry:
+unlock_entry:
 	put_locked_mapping_entry(mapping, pgoff, entry);
- finish_iomap:
+finish_iomap:
 	if (ops->iomap_end) {
 		int copied = PMD_SIZE;
 
@@ -1395,7 +1395,7 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags,
 				&iomap);
 	}
- fallback:
+fallback:
 	if (result == VM_FAULT_FALLBACK) {
 		split_huge_pmd(vma, pmd, address);
 		count_vm_event(THP_FAULT_FALLBACK);
-- 
2.7.4

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#1529085 — Re: [PATCH 2/6] dax: remove leading space from labels

On Wed 23-11-16 11:44:18, Ross Zwisler wrote:
> No functional change.
> 
> As of this commit:
> 
> commit 218dd85887da (".gitattributes: set git diff driver for C source code
> files")
> 
> git-diff and git-format-patch both generate diffs whose hunks are correctly
> prefixed by function names instead of labels, even if those labels aren't
> indented with spaces.

Fine by me. I just have some 4 remaining DAX patches (will send them out
today) and they will clash with this. So I'd prefer if this happened after
they are merged...

								Honza
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> ---
>  fs/dax.c | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index d8fe3eb..cc8a069 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -422,7 +422,7 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
>  		return page;
>  	}
>  	entry = lock_slot(mapping, slot);
> - out_unlock:
> +out_unlock:
>  	spin_unlock_irq(&mapping->tree_lock);
>  	return entry;
>  }
> @@ -557,7 +557,7 @@ static int dax_load_hole(struct address_space *mapping, void **entry,
>  				   vmf->gfp_mask | __GFP_ZERO);
>  	if (!page)
>  		return VM_FAULT_OOM;
> - out:
> +out:
>  	vmf->page = page;
>  	ret = finish_fault(vmf);
>  	vmf->page = NULL;
> @@ -659,7 +659,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
>  	}
>  	if (vmf->flags & FAULT_FLAG_WRITE)
>  		radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
> - unlock:
> +unlock:
>  	spin_unlock_irq(&mapping->tree_lock);
>  	if (hole_fill) {
>  		radix_tree_preload_end();
> @@ -812,12 +812,12 @@ static int dax_writeback_one(struct block_device *bdev,
>  	spin_lock_irq(&mapping->tree_lock);
>  	radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
>  	spin_unlock_irq(&mapping->tree_lock);
> - unmap:
> +unmap:
>  	dax_unmap_atomic(bdev, &dax);
>  	put_locked_mapping_entry(mapping, index, entry);
>  	return ret;
>  
> - put_unlocked:
> +put_unlocked:
>  	put_unlocked_mapping_entry(mapping, index, entry2);
>  	spin_unlock_irq(&mapping->tree_lock);
>  	return ret;
> @@ -1193,11 +1193,11 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
>  		break;
>  	}
>  
> - error_unlock_entry:
> +error_unlock_entry:
>  	vmf_ret = dax_fault_return(error) | major;
> - unlock_entry:
> +unlock_entry:
>  	put_locked_mapping_entry(mapping, vmf->pgoff, entry);
> - finish_iomap:
> +finish_iomap:
>  	if (ops->iomap_end) {
>  		int copied = PAGE_SIZE;
>  
> @@ -1254,7 +1254,7 @@ static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
>  
>  	return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
>  
> - unmap_fallback:
> +unmap_fallback:
>  	dax_unmap_atomic(bdev, &dax);
>  	return VM_FAULT_FALLBACK;
>  }
> @@ -1378,9 +1378,9 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
>  		break;
>  	}
>  
> - unlock_entry:
> +unlock_entry:
>  	put_locked_mapping_entry(mapping, pgoff, entry);
> - finish_iomap:
> +finish_iomap:
>  	if (ops->iomap_end) {
>  		int copied = PMD_SIZE;
>  
> @@ -1395,7 +1395,7 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
>  		ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags,
>  				&iomap);
>  	}
> - fallback:
> +fallback:
>  	if (result == VM_FAULT_FALLBACK) {
>  		split_huge_pmd(vma, pmd, address);
>  		count_vm_event(THP_FAULT_FALLBACK);
> -- 
> 2.7.4
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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#1529654 — Re: [PATCH 2/6] dax: remove leading space from labels

On Thu, Nov 24, 2016 at 1:11 AM, Jan Kara <jack@suse.cz> wrote:
> On Wed 23-11-16 11:44:18, Ross Zwisler wrote:
>> No functional change.
>>
>> As of this commit:
>>
>> commit 218dd85887da (".gitattributes: set git diff driver for C source code
>> files")
>>
>> git-diff and git-format-patch both generate diffs whose hunks are correctly
>> prefixed by function names instead of labels, even if those labels aren't
>> indented with spaces.
>
> Fine by me. I just have some 4 remaining DAX patches (will send them out
> today) and they will clash with this. So I'd prefer if this happened after
> they are merged...

Let's just leave them alone, it's not like this thrash buys us
anything at this point.  We can just stop including spaces in new
code.

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#1528692 — [PATCH 1/6] dax: fix build breakage with ext4, dax and !iomap

With the current Kconfig setup it is possible to have the following:

CONFIG_EXT4_FS=y
CONFIG_FS_DAX=y
CONFIG_FS_IOMAP=n	# this is in fs/Kconfig & isn't user accessible

With this config we get build failures in ext4_dax_fault() because the
iomap functions in fs/dax.c are missing:

fs/built-in.o: In function `ext4_dax_fault':
file.c:(.text+0x7f3ac): undefined reference to `dax_iomap_fault'
file.c:(.text+0x7f404): undefined reference to `dax_iomap_fault'
fs/built-in.o: In function `ext4_file_read_iter':
file.c:(.text+0x7fc54): undefined reference to `dax_iomap_rw'
fs/built-in.o: In function `ext4_file_write_iter':
file.c:(.text+0x7fe9a): undefined reference to `dax_iomap_rw'
file.c:(.text+0x7feed): undefined reference to `dax_iomap_rw'
fs/built-in.o: In function `ext4_block_zero_page_range':
inode.c:(.text+0x85c0d): undefined reference to `iomap_zero_range'

Now that the struct buffer_head based DAX fault paths and I/O path have
been removed we really depend on iomap support being present for DAX.  Make
this explicit by selecting FS_IOMAP if we compile in DAX support.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/Kconfig      | 1 +
 fs/dax.c        | 2 --
 fs/ext2/Kconfig | 1 -
 3 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/Kconfig b/fs/Kconfig
index 8e9e5f41..18024bf 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -38,6 +38,7 @@ config FS_DAX
 	bool "Direct Access (DAX) support"
 	depends on MMU
 	depends on !(ARM || MIPS || SPARC)
+	select FS_IOMAP
 	help
 	  Direct Access (DAX) can be used on memory-backed block devices.
 	  If the block device supports DAX and the filesystem supports DAX,
diff --git a/fs/dax.c b/fs/dax.c
index be39633..d8fe3eb 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -968,7 +968,6 @@ int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
 }
 EXPORT_SYMBOL_GPL(__dax_zero_page_range);
 
-#ifdef CONFIG_FS_IOMAP
 static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
 {
 	return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
@@ -1405,4 +1404,3 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 }
 EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault);
 #endif /* CONFIG_FS_DAX_PMD */
-#endif /* CONFIG_FS_IOMAP */
diff --git a/fs/ext2/Kconfig b/fs/ext2/Kconfig
index 36bea5a..c634874e 100644
--- a/fs/ext2/Kconfig
+++ b/fs/ext2/Kconfig
@@ -1,6 +1,5 @@
 config EXT2_FS
 	tristate "Second extended fs support"
-	select FS_IOMAP if FS_DAX
 	help
 	  Ext2 is a standard Linux file system for hard disks.
 
-- 
2.7.4

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#1529090 — Re: [PATCH 1/6] dax: fix build breakage with ext4, dax and !iomap

On Wed 23-11-16 11:44:17, Ross Zwisler wrote:
> With the current Kconfig setup it is possible to have the following:
> 
> CONFIG_EXT4_FS=y
> CONFIG_FS_DAX=y
> CONFIG_FS_IOMAP=n	# this is in fs/Kconfig & isn't user accessible
> 
> With this config we get build failures in ext4_dax_fault() because the
> iomap functions in fs/dax.c are missing:
> 
> fs/built-in.o: In function `ext4_dax_fault':
> file.c:(.text+0x7f3ac): undefined reference to `dax_iomap_fault'
> file.c:(.text+0x7f404): undefined reference to `dax_iomap_fault'
> fs/built-in.o: In function `ext4_file_read_iter':
> file.c:(.text+0x7fc54): undefined reference to `dax_iomap_rw'
> fs/built-in.o: In function `ext4_file_write_iter':
> file.c:(.text+0x7fe9a): undefined reference to `dax_iomap_rw'
> file.c:(.text+0x7feed): undefined reference to `dax_iomap_rw'
> fs/built-in.o: In function `ext4_block_zero_page_range':
> inode.c:(.text+0x85c0d): undefined reference to `iomap_zero_range'
> 
> Now that the struct buffer_head based DAX fault paths and I/O path have
> been removed we really depend on iomap support being present for DAX.  Make
> this explicit by selecting FS_IOMAP if we compile in DAX support.
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>

I've sent the same patch to Ted yesterday and he will probably queue it on
top of ext4 iomap patches. If it doesn't happen for some reason, feel free
to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/Kconfig      | 1 +
>  fs/dax.c        | 2 --
>  fs/ext2/Kconfig | 1 -
>  3 files changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 8e9e5f41..18024bf 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -38,6 +38,7 @@ config FS_DAX
>  	bool "Direct Access (DAX) support"
>  	depends on MMU
>  	depends on !(ARM || MIPS || SPARC)
> +	select FS_IOMAP
>  	help
>  	  Direct Access (DAX) can be used on memory-backed block devices.
>  	  If the block device supports DAX and the filesystem supports DAX,
> diff --git a/fs/dax.c b/fs/dax.c
> index be39633..d8fe3eb 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -968,7 +968,6 @@ int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
>  }
>  EXPORT_SYMBOL_GPL(__dax_zero_page_range);
>  
> -#ifdef CONFIG_FS_IOMAP
>  static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
>  {
>  	return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
> @@ -1405,4 +1404,3 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
>  }
>  EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault);
>  #endif /* CONFIG_FS_DAX_PMD */
> -#endif /* CONFIG_FS_IOMAP */
> diff --git a/fs/ext2/Kconfig b/fs/ext2/Kconfig
> index 36bea5a..c634874e 100644
> --- a/fs/ext2/Kconfig
> +++ b/fs/ext2/Kconfig
> @@ -1,6 +1,5 @@
>  config EXT2_FS
>  	tristate "Second extended fs support"
> -	select FS_IOMAP if FS_DAX
>  	help
>  	  Ext2 is a standard Linux file system for hard disks.
>  
> -- 
> 2.7.4
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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