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@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>
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@ -4933,7 +4933,8 @@ static int cifs_swap_activate(struct swap_info_struct *sis,
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* from reading or writing the file
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*/
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return 0;
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sis->flags |= SWP_FS_OPS;
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return add_swap_extent(sis, 0, sis->max, 0);
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}
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static void cifs_swap_deactivate(struct file *file)
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@ -483,6 +483,7 @@ static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
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{
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unsigned long blocks;
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long long isize;
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int ret;
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struct inode *inode = file_inode(file);
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struct rpc_clnt *clnt = NFS_CLIENT(inode);
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struct nfs_client *cl = NFS_SERVER(inode)->nfs_client;
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@ -496,13 +497,22 @@ static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
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return -EINVAL;
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}
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*span = sis->pages;
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ret = rpc_clnt_swap_activate(clnt);
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if (ret)
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return ret;
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ret = add_swap_extent(sis, 0, sis->max, 0);
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if (ret < 0) {
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rpc_clnt_swap_deactivate(clnt);
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return ret;
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}
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*span = sis->pages;
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if (cl->rpc_ops->enable_swap)
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cl->rpc_ops->enable_swap(inode);
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return rpc_clnt_swap_activate(clnt);
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sis->flags |= SWP_FS_OPS;
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return ret;
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}
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static void nfs_swap_deactivate(struct file *file)
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@ -577,6 +577,12 @@ static inline swp_entry_t get_swap_page(struct page *page)
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return entry;
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}
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static inline int add_swap_extent(struct swap_info_struct *sis,
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unsigned long start_page,
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unsigned long nr_pages, sector_t start_block)
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{
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return -EINVAL;
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}
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#endif /* CONFIG_SWAP */
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#ifdef CONFIG_THP_SWAP
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@ -2259,13 +2259,9 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
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if (mapping->a_ops->swap_activate) {
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ret = mapping->a_ops->swap_activate(sis, swap_file, span);
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if (ret >= 0)
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sis->flags |= SWP_ACTIVATED;
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if (!ret) {
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sis->flags |= SWP_FS_OPS;
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ret = add_swap_extent(sis, 0, sis->max, 0);
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*span = sis->pages;
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}
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if (ret < 0)
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return ret;
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sis->flags |= SWP_ACTIVATED;
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return ret;
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}
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