From: NeilBrown 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 Reviewed-by: Christoph Hellwig Tested-by: David Howells Tested-by: Geert Uytterhoeven Cc: Hugh Dickins Cc: Mel Gorman Cc: Trond Myklebust Signed-off-by: Andrew Morton --- 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 @@ -4933,7 +4933,8 @@ 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 @@ -577,6 +577,12 @@ 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 @@ -2259,13 +2259,9 @@ 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; } _