@@ -210,8 +210,9 @@ prototypes:
int (*launder_page)(struct page *);
int (*is_partially_uptodate)(struct page *, unsigned long, unsigned long);
int (*error_remove_page)(struct address_space *, struct page *);
- int (*swap_activate)(struct file *);
- int (*swap_deactivate)(struct file *);
+ int (*swap_activate)(struct swap_info_struct *, struct file *,
+ sector_t *);
+ void (*swap_deactivate)(struct file *);
locking rules:
All except set_page_dirty and freepage may block
@@ -235,8 +236,8 @@ putback_page: yes
launder_page: yes
is_partially_uptodate: yes
error_remove_page: yes
-swap_activate: no
-swap_deactivate: no
+swap_activate: yes
+swap_deactivate: no
->write_begin(), ->write_end() and ->readpage() may be called from
the request handler (/dev/loop).
@@ -333,14 +334,10 @@ cleaned, or an error value if not. Note that in order to prevent the page
getting mapped back in and redirtied, it needs to be kept locked
across the entire operation.
- ->swap_activate will be called with a non-zero argument on
-files backing (non block device backed) swapfiles. A return value
-of zero indicates success, in which case this file can be used for
-backing swapspace. The swapspace operations will be proxied to the
-address space operations.
+ ->swap_activate is called from sys_swapon() with the inode locked.
->swap_deactivate() will be called in the sys_swapoff()
-path after ->swap_activate() returned success.
+path after ->swap_activate() returned success. The inode is not locked.
----------------------- file_lock_operations ------------------------------
prototypes:
@@ -652,8 +652,9 @@ struct address_space_operations {
unsigned long);
void (*is_dirty_writeback) (struct page *, bool *, bool *);
int (*error_remove_page) (struct mapping *mapping, struct page *page);
- int (*swap_activate)(struct file *);
- int (*swap_deactivate)(struct file *);
+ int (*swap_activate)(struct swap_info_struct *, struct file *,
+ sector_t *);
+ void (*swap_deactivate)(struct file *);
};
writepage: called by the VM to write a dirty page to backing store.
@@ -830,8 +831,11 @@ struct address_space_operations {
swap_activate: Called when swapon is used on a file to allocate
space if necessary and pin the block lookup information in
- memory. A return value of zero indicates success,
- in which case this file can be used to back swapspace.
+ memory. If this returns zero, the swap system will call the address
+ space operations ->readpage() and ->direct_IO(). Alternatively, this
+ may call add_swap_extent() and return the number of extents added, in
+ which case the swap system will use the provided blocks directly
+ instead of going through the filesystem.
swap_deactivate: Called during swapoff on files where swap_activate
was successful.