Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-pa0-f51.google.com ([209.85.220.51]:39707 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758233AbaKUKJN (ORCPT ); Fri, 21 Nov 2014 05:09:13 -0500 Received: by mail-pa0-f51.google.com with SMTP id ey11so4546502pad.24 for ; Fri, 21 Nov 2014 02:09:12 -0800 (PST) From: Omar Sandoval To: Alexander Viro , Andrew Morton , Chris Mason , Josef Bacik , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, Trond Myklebust , Mel Gorman Cc: Omar Sandoval Subject: [PATCH v2 5/5] btrfs: enable swap file support Date: Fri, 21 Nov 2014 02:08:31 -0800 Message-Id: In-Reply-To: References: In-Reply-To: References: Sender: linux-nfs-owner@vger.kernel.org List-ID: Implement the swap file a_ops on btrfs. Activation simply checks for a usable swap file: it must be fully allocated (no holes), support direct I/O (so no compressed or inline extents) and should be nocow (I'm not sure about that last one). Signed-off-by: Omar Sandoval --- fs/btrfs/inode.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index d23362f..b8fd36b 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -9442,6 +9442,75 @@ out_inode: } +static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file, + sector_t *span) +{ + struct inode *inode = file_inode(file); + struct btrfs_inode *ip = BTRFS_I(inode); + int ret = 0; + u64 isize = inode->i_size; + struct extent_state *cached_state = NULL; + struct extent_map *em; + u64 start, len; + + if (ip->flags & BTRFS_INODE_COMPRESS) { + /* Can't do direct I/O on a compressed file. */ + pr_err("BTRFS: swapfile is compressed"); + return -EINVAL; + } + if (!(ip->flags & BTRFS_INODE_NODATACOW)) { + /* The swap file can't be copy-on-write. */ + pr_err("BTRFS: swapfile is copy-on-write"); + return -EINVAL; + } + + lock_extent_bits(&ip->io_tree, 0, isize - 1, 0, &cached_state); + + /* + * All of the extents must be allocated and support direct I/O. Inline + * extents and compressed extents fall back to buffered I/O, so those + * are no good. + */ + start = 0; + while (start < isize) { + len = isize - start; + em = btrfs_get_extent(inode, NULL, 0, start, len, 0); + if (IS_ERR(em)) { + ret = PTR_ERR(em); + goto out; + } + + if (test_bit(EXTENT_FLAG_VACANCY, &em->flags) || + em->block_start == EXTENT_MAP_HOLE) { + pr_err("BTRFS: swapfile has holes"); + ret = -EINVAL; + goto out; + } + if (em->block_start == EXTENT_MAP_INLINE) { + pr_err("BTRFS: swapfile is inline"); + ret = -EINVAL; + goto out; + } + if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) { + pr_err("BTRFS: swapfile is compresed"); + ret = -EINVAL; + goto out; + } + + start = extent_map_end(em); + free_extent_map(em); + } + +out: + unlock_extent_cached(&ip->io_tree, 0, isize - 1, &cached_state, + GFP_NOFS); + return ret; +} + +static void btrfs_swap_deactivate(struct file *file) +{ +} + static const struct inode_operations btrfs_dir_inode_operations = { .getattr = btrfs_getattr, .lookup = btrfs_lookup, @@ -9519,6 +9588,8 @@ static const struct address_space_operations btrfs_aops = { .releasepage = btrfs_releasepage, .set_page_dirty = btrfs_set_page_dirty, .error_remove_page = generic_error_remove_page, + .swap_activate = btrfs_swap_activate, + .swap_deactivate = btrfs_swap_deactivate, }; static const struct address_space_operations btrfs_symlink_aops = { -- 2.1.3