diff mbox series

[04/14] mm: Add functions to lock invalidate_lock for two mappings

Message ID 20210607145236.31852-4-jack@suse.cz (mailing list archive)
State Superseded
Headers show
Series fs: Hole punch vs page cache filling races | expand

Commit Message

Jan Kara June 7, 2021, 2:52 p.m. UTC
Some operations such as reflinking blocks among files will need to lock
invalidate_lock for two mappings. Add helper functions to do that.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 include/linux/fs.h |  6 ++++++
 mm/filemap.c       | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

Comments

Darrick J. Wong June 7, 2021, 3:46 p.m. UTC | #1
On Mon, Jun 07, 2021 at 04:52:14PM +0200, Jan Kara wrote:
> Some operations such as reflinking blocks among files will need to lock
> invalidate_lock for two mappings. Add helper functions to do that.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>

Straightforward lift from xfs, though now with vfs lock ordering
rules...

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

--D

> ---
>  include/linux/fs.h |  6 ++++++
>  mm/filemap.c       | 38 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 44 insertions(+)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index d8afbc9661d7..ddc11bafc183 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -849,6 +849,12 @@ static inline void filemap_invalidate_unlock_shared(
>  void lock_two_nondirectories(struct inode *, struct inode*);
>  void unlock_two_nondirectories(struct inode *, struct inode*);
>  
> +void filemap_invalidate_lock_two(struct address_space *mapping1,
> +				 struct address_space *mapping2);
> +void filemap_invalidate_unlock_two(struct address_space *mapping1,
> +				   struct address_space *mapping2);
> +
> +
>  /*
>   * NOTE: in a 32bit arch with a preemptable kernel and
>   * an UP compile the i_size_read/write must be atomic
> diff --git a/mm/filemap.c b/mm/filemap.c
> index c8e7e451d81e..b8e9bccecd9f 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1009,6 +1009,44 @@ struct page *__page_cache_alloc(gfp_t gfp)
>  EXPORT_SYMBOL(__page_cache_alloc);
>  #endif
>  
> +/*
> + * filemap_invalidate_lock_two - lock invalidate_lock for two mappings
> + *
> + * Lock exclusively invalidate_lock of any passed mapping that is not NULL.
> + *
> + * @mapping1: the first mapping to lock
> + * @mapping2: the second mapping to lock
> + */
> +void filemap_invalidate_lock_two(struct address_space *mapping1,
> +				 struct address_space *mapping2)
> +{
> +	if (mapping1 > mapping2)
> +		swap(mapping1, mapping2);
> +	if (mapping1)
> +		down_write(&mapping1->invalidate_lock);
> +	if (mapping2 && mapping1 != mapping2)
> +		down_write_nested(&mapping2->invalidate_lock, 1);
> +}
> +EXPORT_SYMBOL(filemap_invalidate_lock_two);
> +
> +/*
> + * filemap_invalidate_unlock_two - unlock invalidate_lock for two mappings
> + *
> + * Unlock exclusive invalidate_lock of any passed mapping that is not NULL.
> + *
> + * @mapping1: the first mapping to unlock
> + * @mapping2: the second mapping to unlock
> + */
> +void filemap_invalidate_unlock_two(struct address_space *mapping1,
> +				   struct address_space *mapping2)
> +{
> +	if (mapping1)
> +		up_write(&mapping1->invalidate_lock);
> +	if (mapping2 && mapping1 != mapping2)
> +		up_write(&mapping2->invalidate_lock);
> +}
> +EXPORT_SYMBOL(filemap_invalidate_unlock_two);
> +
>  /*
>   * In order to wait for pages to become available there must be
>   * waitqueues associated with pages. By using a hash table of
> -- 
> 2.26.2
>
diff mbox series

Patch

diff --git a/include/linux/fs.h b/include/linux/fs.h
index d8afbc9661d7..ddc11bafc183 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -849,6 +849,12 @@  static inline void filemap_invalidate_unlock_shared(
 void lock_two_nondirectories(struct inode *, struct inode*);
 void unlock_two_nondirectories(struct inode *, struct inode*);
 
+void filemap_invalidate_lock_two(struct address_space *mapping1,
+				 struct address_space *mapping2);
+void filemap_invalidate_unlock_two(struct address_space *mapping1,
+				   struct address_space *mapping2);
+
+
 /*
  * NOTE: in a 32bit arch with a preemptable kernel and
  * an UP compile the i_size_read/write must be atomic
diff --git a/mm/filemap.c b/mm/filemap.c
index c8e7e451d81e..b8e9bccecd9f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1009,6 +1009,44 @@  struct page *__page_cache_alloc(gfp_t gfp)
 EXPORT_SYMBOL(__page_cache_alloc);
 #endif
 
+/*
+ * filemap_invalidate_lock_two - lock invalidate_lock for two mappings
+ *
+ * Lock exclusively invalidate_lock of any passed mapping that is not NULL.
+ *
+ * @mapping1: the first mapping to lock
+ * @mapping2: the second mapping to lock
+ */
+void filemap_invalidate_lock_two(struct address_space *mapping1,
+				 struct address_space *mapping2)
+{
+	if (mapping1 > mapping2)
+		swap(mapping1, mapping2);
+	if (mapping1)
+		down_write(&mapping1->invalidate_lock);
+	if (mapping2 && mapping1 != mapping2)
+		down_write_nested(&mapping2->invalidate_lock, 1);
+}
+EXPORT_SYMBOL(filemap_invalidate_lock_two);
+
+/*
+ * filemap_invalidate_unlock_two - unlock invalidate_lock for two mappings
+ *
+ * Unlock exclusive invalidate_lock of any passed mapping that is not NULL.
+ *
+ * @mapping1: the first mapping to unlock
+ * @mapping2: the second mapping to unlock
+ */
+void filemap_invalidate_unlock_two(struct address_space *mapping1,
+				   struct address_space *mapping2)
+{
+	if (mapping1)
+		up_write(&mapping1->invalidate_lock);
+	if (mapping2 && mapping1 != mapping2)
+		up_write(&mapping2->invalidate_lock);
+}
+EXPORT_SYMBOL(filemap_invalidate_unlock_two);
+
 /*
  * In order to wait for pages to become available there must be
  * waitqueues associated with pages. By using a hash table of