The patch titled
Subject: mm: move responsibility for setting SWP_FS_OPS to ->swap_activate
has been added to the -mm tree. Its filename is
mm-move-responsibility-for-setting-swp_fs_ops-to-swap_activate.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-move-responsibility-for-setting-swp_fs_ops-to-swap_activate.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-move-responsibility-for-setting-swp_fs_ops-to-swap_activate.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: NeilBrown <neilb@xxxxxxx>
Subject: mm: move responsibility for setting SWP_FS_OPS to ->swap_activate
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@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/cifs/file.c | 3 ++-
fs/nfs/file.c | 14 ++++++++++++--
include/linux/swap.h | 6 ++++++
mm/swapfile.c | 10 +++-------
4 files changed, 23 insertions(+), 10 deletions(-)
--- a/fs/cifs/file.c~mm-move-responsibility-for-setting-swp_fs_ops-to-swap_activate
+++ a/fs/cifs/file.c
@@ -4927,7 +4927,8 @@ static int cifs_swap_activate(struct swa
* from reading or writing the file
*/
- return 0;
+ sis->flags |= SWP_FS_OPS;
+ return add_swap_extent(sis, 0, sis->max, 0);
}
static void cifs_swap_deactivate(struct file *file)
--- a/fs/nfs/file.c~mm-move-responsibility-for-setting-swp_fs_ops-to-swap_activate
+++ a/fs/nfs/file.c
@@ -483,6 +483,7 @@ static int nfs_swap_activate(struct swap
{
unsigned long blocks;
long long isize;
+ int ret;
struct inode *inode = file_inode(file);
struct rpc_clnt *clnt = NFS_CLIENT(inode);
struct nfs_client *cl = NFS_SERVER(inode)->nfs_client;
@@ -496,13 +497,22 @@ static int nfs_swap_activate(struct swap
return -EINVAL;
}
- *span = sis->pages;
+ ret = rpc_clnt_swap_activate(clnt);
+ if (ret)
+ return ret;
+ ret = add_swap_extent(sis, 0, sis->max, 0);
+ if (ret < 0) {
+ rpc_clnt_swap_deactivate(clnt);
+ return ret;
+ }
+ *span = sis->pages;
if (cl->rpc_ops->enable_swap)
cl->rpc_ops->enable_swap(inode);
- return rpc_clnt_swap_activate(clnt);
+ sis->flags |= SWP_FS_OPS;
+ return ret;
}
static void nfs_swap_deactivate(struct file *file)
--- a/include/linux/swap.h~mm-move-responsibility-for-setting-swp_fs_ops-to-swap_activate
+++ a/include/linux/swap.h
@@ -570,6 +570,12 @@ static inline swp_entry_t get_swap_page(
return entry;
}
+static inline int add_swap_extent(struct swap_info_struct *sis,
+ unsigned long start_page,
+ unsigned long nr_pages, sector_t start_block)
+{
+ return -EINVAL;
+}
#endif /* CONFIG_SWAP */
#ifdef CONFIG_THP_SWAP
--- a/mm/swapfile.c~mm-move-responsibility-for-setting-swp_fs_ops-to-swap_activate
+++ a/mm/swapfile.c
@@ -2244,13 +2244,9 @@ static int setup_swap_extents(struct swa
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;
}
_
Patches currently in -mm which might be from neilb@xxxxxxx are
mm-create-new-mm-swaph-header-file.patch
mm-drop-swap_dirty_folio.patch
mm-move-responsibility-for-setting-swp_fs_ops-to-swap_activate.patch
mm-reclaim-mustnt-enter-fs-for-swp_fs_ops-swap-space.patch
mm-introduce-swap_rw-and-use-it-for-reads-from-swp_fs_ops-swap-space.patch
mm-perform-async-writes-to-swp_fs_ops-swap-space-using-swap_rw.patch
doc-update-documentation-for-swap_activate-and-swap_rw.patch
mm-submit-multipage-reads-for-swp_fs_ops-swap-space.patch
mm-submit-multipage-write-for-swp_fs_ops-swap-space.patch
vfs-add-fmode_can_odirect-file-flag.patch
mm-discard-__gfp_atomic.patch
