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authorNeilBrown <neilb@suse.de>2022-05-10 04:20:48 +0300
committerakpm <akpm@linux-foundation.org>2022-05-10 04:20:48 +0300
commitcba738f6490953e154d163b2980ad6d7f06307aa (patch)
tree356ca9d01361a81151f257ddde45d57be4c13c6d /Documentation/filesystems/vfs.rst
parent7eadabc05d45ecedc0e8906d1db46bc8cfeb02af (diff)
downloadlinux-cba738f6490953e154d163b2980ad6d7f06307aa.tar.xz
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swap_activate() has been out-of-date for a long time.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@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: David Howells <dhowells@redhat.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems/vfs.rst')
-rw-r--r--Documentation/filesystems/vfs.rst17
1 files changed, 12 insertions, 5 deletions
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index 794bd1a66bfb..d4bd213d215b 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -749,8 +749,9 @@ cache in your filesystem. The following members are defined:
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 members are defined:
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
===============