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mm: move responsibility for setting SWP_FS_OPS to ->swap_activate

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If a filesystem wishes to handle all swap IO itself (via ->direct_IO and
->readpage), rather than just providing devices addresses for
submit_bio(), SWP_FS_OPS must be set.

Currently the protocol for setting this it to have ->swap_activate return
zero.  In that case SWP_FS_OPS is set, and add_swap_extent() is called for
the entire file.

This is a little clumsy as different return values for ->swap_activate
have quite different meanings, and it makes it hard to search for which
filesystems require SWP_FS_OPS to be set.

So remove the special meaning of a zero return, and require the filesystem
to set SWP_FS_OPS if it so desires, and to always call add_swap_extent()
as required.

Currently only NFS and CIFS return zero for add_swap_extent().

Link: https://lkml.kernel.org/r/164859778123.29473.17908205846599043598.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>
This commit is contained in:
NeilBrown
2022-05-09 18:20:48 -07:00
committed by akpm
parent 4c4a763406
commit 4b60c0ff2f
4 changed files with 23 additions and 10 deletions
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10
mm/swapfile.c
View File

@ -2259,13 +2259,9 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
if (mapping->a_ops->swap_activate) {
ret = mapping->a_ops->swap_activate(sis, swap_file, span);
if (ret >= 0)
sis->flags |= SWP_ACTIVATED;
if (!ret) {
sis->flags |= SWP_FS_OPS;
ret = add_swap_extent(sis, 0, sis->max, 0);
*span = sis->pages;
}
if (ret < 0)
return ret;
sis->flags |= SWP_ACTIVATED;
return ret;
}