The quilt patch titled
Subject: doc: update documentation for swap_activate and swap_rw
has been removed from the -mm tree. Its filename was
doc-update-documentation-for-swap_activate-and-swap_rw.patch
This patch was dropped because it was merged into mm-stable
------------------------------------------------------
From: NeilBrown <neilb@xxxxxxx>
Subject: doc: update documentation for swap_activate and swap_rw
This documentation for ->swap_activate() has been out-of-date for a long
time. This patch updates it to match recent changes, and adds
documentation for the associated ->swap_rw()
Link: https://lkml.kernel.org/r/164859778126.29473.6778751233552859461.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Tested-by: David Howells <dhowells@xxxxxxxxxx>
Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/locking.rst | 18 ++++++++++++------
Documentation/filesystems/vfs.rst | 17 ++++++++++++-----
2 files changed, 24 insertions(+), 11 deletions(-)
--- a/Documentation/filesystems/locking.rst~doc-update-documentation-for-swap_activate-and-swap_rw
+++ a/Documentation/filesystems/locking.rst
@@ -258,8 +258,9 @@ prototypes::
int (*launder_folio)(struct folio *);
bool (*is_partially_uptodate)(struct folio *, size_t from, size_t count);
int (*error_remove_page)(struct address_space *, struct page *);
- int (*swap_activate)(struct file *);
+ int (*swap_activate)(struct swap_info_struct *sis, struct file *f, sector_t *span)
int (*swap_deactivate)(struct file *);
+ int (*swap_rw)(struct kiocb *iocb, struct iov_iter *iter);
locking rules:
All except dirty_folio and freepage may block
@@ -287,6 +288,7 @@ is_partially_uptodate: yes
error_remove_page: yes
swap_activate: no
swap_deactivate: no
+swap_rw: yes, unlocks
====================== ======================== ========= ===============
->write_begin(), ->write_end() and ->readpage() may be called from
@@ -386,15 +388,19 @@ cleaned, or an error value if not. Note
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() will be called to prepare the given file for swap. It
+should perform any validation and preparation necessary to ensure that
+writes can be performed with minimal memory allocation. It should call
+add_swap_extent(), or the helper iomap_swapfile_activate(), and return
+the number of extents added. If IO should be submitted through
+->swap_rw(), it should set SWP_FS_OPS, otherwise IO will be submitted
+directly to the block device ``sis->bdev``.
->swap_deactivate() will be called in the sys_swapoff()
path after ->swap_activate() returned success.
+->swap_rw will be called for swap IO if SWP_FS_OPS was set by ->swap_activate().
+
file_lock_operations
====================
--- a/Documentation/filesystems/vfs.rst~doc-update-documentation-for-swap_activate-and-swap_rw
+++ a/Documentation/filesystems/vfs.rst
@@ -749,8 +749,9 @@ cache in your filesystem. The following
size_t count);
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_activate)(struct swap_info_struct *sis, struct file *f, sector_t *span)
int (*swap_deactivate)(struct file *);
+ int (*swap_rw)(struct kiocb *iocb, struct iov_iter *iter);
};
``writepage``
@@ -952,15 +953,21 @@ cache in your filesystem. The following
unless you have them locked or reference counts increased.
``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.
+
+ Called to prepare the given file for swap. It should perform
+ any validation and preparation necessary to ensure that writes
+ can be performed with minimal memory allocation. It should call
+ add_swap_extent(), or the helper iomap_swapfile_activate(), and
+ return the number of extents added. If IO should be submitted
+ through ->swap_rw(), it should set SWP_FS_OPS, otherwise IO will
+ be submitted directly to the block device ``sis->bdev``.
``swap_deactivate``
Called during swapoff on files where swap_activate was
successful.
+``swap_rw``
+ Called to read or write swap pages when SWP_FS_OPS is set.
The File Object
===============
_
Patches currently in -mm which might be from neilb@xxxxxxx are
mm-discard-__gfp_atomic.patch
