From 1cf7a1518aefa69ac6ba0c3f9206073e4221e3c8 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 2 Nov 2017 15:27:52 +0000 Subject: afs: Implement shared-writeable mmap Implement shared-writeable mmap for AFS. Signed-off-by: David Howells --- fs/afs/write.c | 40 ++++++++++++++++++++++++++++++++-------- 1 file changed, 32 insertions(+), 8 deletions(-) (limited to 'fs/afs/write.c') diff --git a/fs/afs/write.c b/fs/afs/write.c index 4c131371005b..6807277ef956 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -749,21 +749,45 @@ int afs_flush(struct file *file, fl_owner_t id) * notification that a previously read-only page is about to become writable * - if it returns an error, the caller will deliver a bus error signal */ -int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page) +int afs_page_mkwrite(struct vm_fault *vmf) { - struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host); + struct file *file = vmf->vma->vm_file; + struct inode *inode = file_inode(file); + struct afs_vnode *vnode = AFS_FS_I(inode); + unsigned long priv; _enter("{{%x:%u}},{%lx}", - vnode->fid.vid, vnode->fid.vnode, page->index); + vnode->fid.vid, vnode->fid.vnode, vmf->page->index); - /* wait for the page to be written to the cache before we allow it to - * be modified */ + sb_start_pagefault(inode->i_sb); + + /* Wait for the page to be written to the cache before we allow it to + * be modified. We then assume the entire page will need writing back. + */ #ifdef CONFIG_AFS_FSCACHE - fscache_wait_on_page_write(vnode->cache, page); + fscache_wait_on_page_write(vnode->cache, vmf->page); #endif - _leave(" = 0"); - return 0; + if (PageWriteback(vmf->page) && + wait_on_page_bit_killable(vmf->page, PG_writeback) < 0) + return VM_FAULT_RETRY; + + if (lock_page_killable(vmf->page) < 0) + return VM_FAULT_RETRY; + + /* We mustn't change page->private until writeback is complete as that + * details the portion of the page we need to write back and we might + * need to redirty the page if there's a problem. + */ + wait_on_page_writeback(vmf->page); + + priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */ + priv |= 0; /* From */ + SetPagePrivate(vmf->page); + set_page_private(vmf->page, priv); + + sb_end_pagefault(inode->i_sb); + return VM_FAULT_LOCKED; } /* -- cgit v1.2.3-59-g8ed1b