diff mbox series

[v2,4/8] fsdax,xfs: set the shared flag when file extent is shared

Message ID 1669908538-55-5-git-send-email-ruansy.fnst@fujitsu.com (mailing list archive)
State Accepted
Commit c6f0b395b2110aa26a134a9a395875b1ec0a5aae
Headers show
Series fsdax,xfs: fix warning messages | expand

Commit Message

Shiyang Ruan Dec. 1, 2022, 3:28 p.m. UTC 
If a dax page is shared, mapread at different offsets can also trigger
page fault on same dax page.  So, change the flag from "cow" to
"shared".  And get the shared flag from filesystem when read.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
 fs/dax.c           | 19 +++++++------------
 fs/xfs/xfs_iomap.c |  2 +-
 2 files changed, 8 insertions(+), 13 deletions(-)

Comments

Darrick J. Wong Dec. 2, 2022, 12:05 a.m. UTC | #1 
On Thu, Dec 01, 2022 at 03:28:54PM +0000, Shiyang Ruan wrote:
> If a dax page is shared, mapread at different offsets can also trigger
> page fault on same dax page.  So, change the flag from "cow" to
> "shared".  And get the shared flag from filesystem when read.
> 
> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>

Makes sense.
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/dax.c           | 19 +++++++------------
>  fs/xfs/xfs_iomap.c |  2 +-
>  2 files changed, 8 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 6b6e07ad8d80..f1eb59bee0b5 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -846,12 +846,6 @@ static bool dax_fault_is_synchronous(const struct iomap_iter *iter,
>  		(iter->iomap.flags & IOMAP_F_DIRTY);
>  }
>  
> -static bool dax_fault_is_cow(const struct iomap_iter *iter)
> -{
> -	return (iter->flags & IOMAP_WRITE) &&
> -		(iter->iomap.flags & IOMAP_F_SHARED);
> -}
> -
>  /*
>   * By this point grab_mapping_entry() has ensured that we have a locked entry
>   * of the appropriate size so we don't have to worry about downgrading PMDs to
> @@ -865,13 +859,14 @@ static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
>  {
>  	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
>  	void *new_entry = dax_make_entry(pfn, flags);
> -	bool dirty = !dax_fault_is_synchronous(iter, vmf->vma);
> -	bool cow = dax_fault_is_cow(iter);
> +	bool write = iter->flags & IOMAP_WRITE;
> +	bool dirty = write && !dax_fault_is_synchronous(iter, vmf->vma);
> +	bool shared = iter->iomap.flags & IOMAP_F_SHARED;
>  
>  	if (dirty)
>  		__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
>  
> -	if (cow || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) {
> +	if (shared || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) {
>  		unsigned long index = xas->xa_index;
>  		/* we are replacing a zero page with block mapping */
>  		if (dax_is_pmd_entry(entry))
> @@ -883,12 +878,12 @@ static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
>  
>  	xas_reset(xas);
>  	xas_lock_irq(xas);
> -	if (cow || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
> +	if (shared || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
>  		void *old;
>  
>  		dax_disassociate_entry(entry, mapping, false);
>  		dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address,
> -				cow);
> +				shared);
>  		/*
>  		 * Only swap our new entry into the page cache if the current
>  		 * entry is a zero page or an empty entry.  If a normal PTE or
> @@ -908,7 +903,7 @@ static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
>  	if (dirty)
>  		xas_set_mark(xas, PAGECACHE_TAG_DIRTY);
>  
> -	if (cow)
> +	if (write && shared)
>  		xas_set_mark(xas, PAGECACHE_TAG_TOWRITE);
>  
>  	xas_unlock_irq(xas);
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 07da03976ec1..881de99766ca 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1215,7 +1215,7 @@ xfs_read_iomap_begin(
>  		return error;
>  	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
>  			       &nimaps, 0);
> -	if (!error && (flags & IOMAP_REPORT))
> +	if (!error && ((flags & IOMAP_REPORT) || IS_DAX(inode)))
>  		error = xfs_reflink_trim_around_shared(ip, &imap, &shared);
>  	xfs_iunlock(ip, lockmode);
>  
> -- 
> 2.38.1
>
diff mbox series

Patch

diff --git a/fs/dax.c b/fs/dax.c
index 6b6e07ad8d80..f1eb59bee0b5 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -846,12 +846,6 @@  static bool dax_fault_is_synchronous(const struct iomap_iter *iter,
 		(iter->iomap.flags & IOMAP_F_DIRTY);
 }
 
-static bool dax_fault_is_cow(const struct iomap_iter *iter)
-{
-	return (iter->flags & IOMAP_WRITE) &&
-		(iter->iomap.flags & IOMAP_F_SHARED);
-}
-
 /*
  * By this point grab_mapping_entry() has ensured that we have a locked entry
  * of the appropriate size so we don't have to worry about downgrading PMDs to
@@ -865,13 +859,14 @@  static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
 {
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
 	void *new_entry = dax_make_entry(pfn, flags);
-	bool dirty = !dax_fault_is_synchronous(iter, vmf->vma);
-	bool cow = dax_fault_is_cow(iter);
+	bool write = iter->flags & IOMAP_WRITE;
+	bool dirty = write && !dax_fault_is_synchronous(iter, vmf->vma);
+	bool shared = iter->iomap.flags & IOMAP_F_SHARED;
 
 	if (dirty)
 		__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 
-	if (cow || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) {
+	if (shared || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) {
 		unsigned long index = xas->xa_index;
 		/* we are replacing a zero page with block mapping */
 		if (dax_is_pmd_entry(entry))
@@ -883,12 +878,12 @@  static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
 
 	xas_reset(xas);
 	xas_lock_irq(xas);
-	if (cow || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
+	if (shared || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
 		void *old;
 
 		dax_disassociate_entry(entry, mapping, false);
 		dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address,
-				cow);
+				shared);
 		/*
 		 * Only swap our new entry into the page cache if the current
 		 * entry is a zero page or an empty entry.  If a normal PTE or
@@ -908,7 +903,7 @@  static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
 	if (dirty)
 		xas_set_mark(xas, PAGECACHE_TAG_DIRTY);
 
-	if (cow)
+	if (write && shared)
 		xas_set_mark(xas, PAGECACHE_TAG_TOWRITE);
 
 	xas_unlock_irq(xas);
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 07da03976ec1..881de99766ca 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1215,7 +1215,7 @@  xfs_read_iomap_begin(
 		return error;
 	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
 			       &nimaps, 0);
-	if (!error && (flags & IOMAP_REPORT))
+	if (!error && ((flags & IOMAP_REPORT) || IS_DAX(inode)))
 		error = xfs_reflink_trim_around_shared(ip, &imap, &shared);
 	xfs_iunlock(ip, lockmode);