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afs: Implement shared-writeable mmap

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Implement shared-writeable mmap for AFS.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells
2017-11-02 15:27:52 +00:00
parent 4343d00872
commit 1cf7a1518a
3 changed files with 54 additions and 9 deletions
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40
fs/afs/write.c
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@@ -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;
}
/*