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762 lines
18 KiB
C
762 lines
18 KiB
C
/* handling of writes to regular files and writing back to the server
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/backing-dev.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/writeback.h>
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#include <linux/pagevec.h>
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#include <linux/aio.h>
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#include "internal.h"
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static int afs_write_back_from_locked_page(struct afs_writeback *wb,
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struct page *page);
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/*
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* mark a page as having been made dirty and thus needing writeback
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*/
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int afs_set_page_dirty(struct page *page)
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{
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_enter("");
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return __set_page_dirty_nobuffers(page);
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}
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/*
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* unlink a writeback record because its usage has reached zero
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* - must be called with the wb->vnode->writeback_lock held
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*/
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static void afs_unlink_writeback(struct afs_writeback *wb)
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{
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struct afs_writeback *front;
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struct afs_vnode *vnode = wb->vnode;
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list_del_init(&wb->link);
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if (!list_empty(&vnode->writebacks)) {
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/* if an fsync rises to the front of the queue then wake it
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* up */
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front = list_entry(vnode->writebacks.next,
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struct afs_writeback, link);
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if (front->state == AFS_WBACK_SYNCING) {
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_debug("wake up sync");
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front->state = AFS_WBACK_COMPLETE;
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wake_up(&front->waitq);
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}
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}
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}
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/*
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* free a writeback record
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*/
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static void afs_free_writeback(struct afs_writeback *wb)
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{
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_enter("");
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key_put(wb->key);
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kfree(wb);
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}
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/*
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* dispose of a reference to a writeback record
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*/
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void afs_put_writeback(struct afs_writeback *wb)
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{
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struct afs_vnode *vnode = wb->vnode;
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_enter("{%d}", wb->usage);
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spin_lock(&vnode->writeback_lock);
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if (--wb->usage == 0)
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afs_unlink_writeback(wb);
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else
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wb = NULL;
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spin_unlock(&vnode->writeback_lock);
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if (wb)
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afs_free_writeback(wb);
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}
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/*
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* partly or wholly fill a page that's under preparation for writing
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*/
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static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
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loff_t pos, struct page *page)
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{
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loff_t i_size;
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int ret;
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int len;
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_enter(",,%llu", (unsigned long long)pos);
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i_size = i_size_read(&vnode->vfs_inode);
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if (pos + PAGE_CACHE_SIZE > i_size)
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len = i_size - pos;
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else
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len = PAGE_CACHE_SIZE;
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ret = afs_vnode_fetch_data(vnode, key, pos, len, page);
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if (ret < 0) {
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if (ret == -ENOENT) {
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_debug("got NOENT from server"
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" - marking file deleted and stale");
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set_bit(AFS_VNODE_DELETED, &vnode->flags);
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ret = -ESTALE;
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}
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}
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* prepare to perform part of a write to a page
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*/
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int afs_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata)
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{
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struct afs_writeback *candidate, *wb;
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struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
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struct page *page;
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struct key *key = file->private_data;
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unsigned from = pos & (PAGE_CACHE_SIZE - 1);
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unsigned to = from + len;
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pgoff_t index = pos >> PAGE_CACHE_SHIFT;
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int ret;
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_enter("{%x:%u},{%lx},%u,%u",
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vnode->fid.vid, vnode->fid.vnode, index, from, to);
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candidate = kzalloc(sizeof(*candidate), GFP_KERNEL);
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if (!candidate)
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return -ENOMEM;
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candidate->vnode = vnode;
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candidate->first = candidate->last = index;
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candidate->offset_first = from;
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candidate->to_last = to;
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INIT_LIST_HEAD(&candidate->link);
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candidate->usage = 1;
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candidate->state = AFS_WBACK_PENDING;
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init_waitqueue_head(&candidate->waitq);
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page = grab_cache_page_write_begin(mapping, index, flags);
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if (!page) {
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kfree(candidate);
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return -ENOMEM;
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}
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*pagep = page;
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/* page won't leak in error case: it eventually gets cleaned off LRU */
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if (!PageUptodate(page) && len != PAGE_CACHE_SIZE) {
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ret = afs_fill_page(vnode, key, index << PAGE_CACHE_SHIFT, page);
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if (ret < 0) {
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kfree(candidate);
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_leave(" = %d [prep]", ret);
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return ret;
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}
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SetPageUptodate(page);
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}
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try_again:
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spin_lock(&vnode->writeback_lock);
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/* see if this page is already pending a writeback under a suitable key
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* - if so we can just join onto that one */
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wb = (struct afs_writeback *) page_private(page);
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if (wb) {
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if (wb->key == key && wb->state == AFS_WBACK_PENDING)
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goto subsume_in_current_wb;
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goto flush_conflicting_wb;
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}
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if (index > 0) {
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/* see if we can find an already pending writeback that we can
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* append this page to */
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list_for_each_entry(wb, &vnode->writebacks, link) {
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if (wb->last == index - 1 && wb->key == key &&
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wb->state == AFS_WBACK_PENDING)
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goto append_to_previous_wb;
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}
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}
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list_add_tail(&candidate->link, &vnode->writebacks);
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candidate->key = key_get(key);
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spin_unlock(&vnode->writeback_lock);
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SetPagePrivate(page);
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set_page_private(page, (unsigned long) candidate);
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_leave(" = 0 [new]");
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return 0;
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subsume_in_current_wb:
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_debug("subsume");
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ASSERTRANGE(wb->first, <=, index, <=, wb->last);
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if (index == wb->first && from < wb->offset_first)
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wb->offset_first = from;
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if (index == wb->last && to > wb->to_last)
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wb->to_last = to;
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spin_unlock(&vnode->writeback_lock);
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kfree(candidate);
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_leave(" = 0 [sub]");
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return 0;
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append_to_previous_wb:
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_debug("append into %lx-%lx", wb->first, wb->last);
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wb->usage++;
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wb->last++;
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wb->to_last = to;
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spin_unlock(&vnode->writeback_lock);
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SetPagePrivate(page);
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set_page_private(page, (unsigned long) wb);
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kfree(candidate);
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_leave(" = 0 [app]");
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return 0;
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/* the page is currently bound to another context, so if it's dirty we
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* need to flush it before we can use the new context */
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flush_conflicting_wb:
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_debug("flush conflict");
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if (wb->state == AFS_WBACK_PENDING)
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wb->state = AFS_WBACK_CONFLICTING;
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spin_unlock(&vnode->writeback_lock);
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if (PageDirty(page)) {
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ret = afs_write_back_from_locked_page(wb, page);
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if (ret < 0) {
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afs_put_writeback(candidate);
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_leave(" = %d", ret);
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return ret;
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}
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}
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/* the page holds a ref on the writeback record */
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afs_put_writeback(wb);
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set_page_private(page, 0);
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ClearPagePrivate(page);
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goto try_again;
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}
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/*
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* finalise part of a write to a page
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*/
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int afs_write_end(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned copied,
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struct page *page, void *fsdata)
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{
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struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
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loff_t i_size, maybe_i_size;
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_enter("{%x:%u},{%lx}",
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vnode->fid.vid, vnode->fid.vnode, page->index);
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maybe_i_size = pos + copied;
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i_size = i_size_read(&vnode->vfs_inode);
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if (maybe_i_size > i_size) {
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spin_lock(&vnode->writeback_lock);
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i_size = i_size_read(&vnode->vfs_inode);
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if (maybe_i_size > i_size)
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i_size_write(&vnode->vfs_inode, maybe_i_size);
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spin_unlock(&vnode->writeback_lock);
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}
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set_page_dirty(page);
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if (PageDirty(page))
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_debug("dirtied");
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unlock_page(page);
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page_cache_release(page);
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return copied;
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}
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/*
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* kill all the pages in the given range
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*/
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static void afs_kill_pages(struct afs_vnode *vnode, bool error,
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pgoff_t first, pgoff_t last)
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{
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struct pagevec pv;
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unsigned count, loop;
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_enter("{%x:%u},%lx-%lx",
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vnode->fid.vid, vnode->fid.vnode, first, last);
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pagevec_init(&pv, 0);
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do {
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_debug("kill %lx-%lx", first, last);
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count = last - first + 1;
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if (count > PAGEVEC_SIZE)
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count = PAGEVEC_SIZE;
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pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
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first, count, pv.pages);
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ASSERTCMP(pv.nr, ==, count);
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for (loop = 0; loop < count; loop++) {
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ClearPageUptodate(pv.pages[loop]);
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if (error)
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SetPageError(pv.pages[loop]);
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end_page_writeback(pv.pages[loop]);
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}
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__pagevec_release(&pv);
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} while (first < last);
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_leave("");
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}
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/*
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* synchronously write back the locked page and any subsequent non-locked dirty
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* pages also covered by the same writeback record
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*/
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static int afs_write_back_from_locked_page(struct afs_writeback *wb,
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struct page *primary_page)
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{
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struct page *pages[8], *page;
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unsigned long count;
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unsigned n, offset, to;
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pgoff_t start, first, last;
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int loop, ret;
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_enter(",%lx", primary_page->index);
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count = 1;
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if (!clear_page_dirty_for_io(primary_page))
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BUG();
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if (test_set_page_writeback(primary_page))
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BUG();
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/* find all consecutive lockable dirty pages, stopping when we find a
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* page that is not immediately lockable, is not dirty or is missing,
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* or we reach the end of the range */
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start = primary_page->index;
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if (start >= wb->last)
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goto no_more;
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start++;
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do {
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_debug("more %lx [%lx]", start, count);
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n = wb->last - start + 1;
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if (n > ARRAY_SIZE(pages))
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n = ARRAY_SIZE(pages);
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n = find_get_pages_contig(wb->vnode->vfs_inode.i_mapping,
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start, n, pages);
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_debug("fgpc %u", n);
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if (n == 0)
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goto no_more;
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if (pages[0]->index != start) {
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do {
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put_page(pages[--n]);
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} while (n > 0);
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goto no_more;
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}
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for (loop = 0; loop < n; loop++) {
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page = pages[loop];
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if (page->index > wb->last)
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break;
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if (!trylock_page(page))
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break;
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if (!PageDirty(page) ||
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page_private(page) != (unsigned long) wb) {
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unlock_page(page);
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break;
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}
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if (!clear_page_dirty_for_io(page))
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BUG();
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if (test_set_page_writeback(page))
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BUG();
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unlock_page(page);
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put_page(page);
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}
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count += loop;
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if (loop < n) {
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for (; loop < n; loop++)
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put_page(pages[loop]);
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goto no_more;
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}
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start += loop;
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} while (start <= wb->last && count < 65536);
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no_more:
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/* we now have a contiguous set of dirty pages, each with writeback set
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* and the dirty mark cleared; the first page is locked and must remain
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* so, all the rest are unlocked */
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first = primary_page->index;
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last = first + count - 1;
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offset = (first == wb->first) ? wb->offset_first : 0;
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to = (last == wb->last) ? wb->to_last : PAGE_SIZE;
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_debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
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ret = afs_vnode_store_data(wb, first, last, offset, to);
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if (ret < 0) {
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switch (ret) {
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case -EDQUOT:
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case -ENOSPC:
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set_bit(AS_ENOSPC,
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&wb->vnode->vfs_inode.i_mapping->flags);
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break;
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case -EROFS:
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case -EIO:
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case -EREMOTEIO:
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case -EFBIG:
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case -ENOENT:
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case -ENOMEDIUM:
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case -ENXIO:
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afs_kill_pages(wb->vnode, true, first, last);
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set_bit(AS_EIO, &wb->vnode->vfs_inode.i_mapping->flags);
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break;
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case -EACCES:
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case -EPERM:
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case -ENOKEY:
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case -EKEYEXPIRED:
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case -EKEYREJECTED:
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case -EKEYREVOKED:
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afs_kill_pages(wb->vnode, false, first, last);
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break;
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default:
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break;
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}
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} else {
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ret = count;
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}
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* write a page back to the server
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* - the caller locked the page for us
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*/
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int afs_writepage(struct page *page, struct writeback_control *wbc)
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{
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struct afs_writeback *wb;
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int ret;
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_enter("{%lx},", page->index);
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wb = (struct afs_writeback *) page_private(page);
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ASSERT(wb != NULL);
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ret = afs_write_back_from_locked_page(wb, page);
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unlock_page(page);
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if (ret < 0) {
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_leave(" = %d", ret);
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return 0;
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}
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wbc->nr_to_write -= ret;
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_leave(" = 0");
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return 0;
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}
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/*
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* write a region of pages back to the server
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*/
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static int afs_writepages_region(struct address_space *mapping,
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struct writeback_control *wbc,
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pgoff_t index, pgoff_t end, pgoff_t *_next)
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{
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struct afs_writeback *wb;
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struct page *page;
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int ret, n;
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_enter(",,%lx,%lx,", index, end);
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do {
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n = find_get_pages_tag(mapping, &index, PAGECACHE_TAG_DIRTY,
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1, &page);
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if (!n)
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break;
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_debug("wback %lx", page->index);
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if (page->index > end) {
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*_next = index;
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page_cache_release(page);
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_leave(" = 0 [%lx]", *_next);
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return 0;
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}
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/* at this point we hold neither mapping->tree_lock nor lock on
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* the page itself: the page may be truncated or invalidated
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* (changing page->mapping to NULL), or even swizzled back from
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* swapper_space to tmpfs file mapping
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*/
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lock_page(page);
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if (page->mapping != mapping) {
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unlock_page(page);
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page_cache_release(page);
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continue;
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}
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if (wbc->sync_mode != WB_SYNC_NONE)
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wait_on_page_writeback(page);
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if (PageWriteback(page) || !PageDirty(page)) {
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unlock_page(page);
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continue;
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}
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wb = (struct afs_writeback *) page_private(page);
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ASSERT(wb != NULL);
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spin_lock(&wb->vnode->writeback_lock);
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wb->state = AFS_WBACK_WRITING;
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spin_unlock(&wb->vnode->writeback_lock);
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ret = afs_write_back_from_locked_page(wb, page);
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unlock_page(page);
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page_cache_release(page);
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if (ret < 0) {
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_leave(" = %d", ret);
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return ret;
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}
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wbc->nr_to_write -= ret;
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cond_resched();
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} while (index < end && wbc->nr_to_write > 0);
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|
|
*_next = index;
|
|
_leave(" = 0 [%lx]", *_next);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* write some of the pending data back to the server
|
|
*/
|
|
int afs_writepages(struct address_space *mapping,
|
|
struct writeback_control *wbc)
|
|
{
|
|
pgoff_t start, end, next;
|
|
int ret;
|
|
|
|
_enter("");
|
|
|
|
if (wbc->range_cyclic) {
|
|
start = mapping->writeback_index;
|
|
end = -1;
|
|
ret = afs_writepages_region(mapping, wbc, start, end, &next);
|
|
if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
|
|
ret = afs_writepages_region(mapping, wbc, 0, start,
|
|
&next);
|
|
mapping->writeback_index = next;
|
|
} else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
|
|
end = (pgoff_t)(LLONG_MAX >> PAGE_CACHE_SHIFT);
|
|
ret = afs_writepages_region(mapping, wbc, 0, end, &next);
|
|
if (wbc->nr_to_write > 0)
|
|
mapping->writeback_index = next;
|
|
} else {
|
|
start = wbc->range_start >> PAGE_CACHE_SHIFT;
|
|
end = wbc->range_end >> PAGE_CACHE_SHIFT;
|
|
ret = afs_writepages_region(mapping, wbc, start, end, &next);
|
|
}
|
|
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* completion of write to server
|
|
*/
|
|
void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
|
|
{
|
|
struct afs_writeback *wb = call->wb;
|
|
struct pagevec pv;
|
|
unsigned count, loop;
|
|
pgoff_t first = call->first, last = call->last;
|
|
bool free_wb;
|
|
|
|
_enter("{%x:%u},{%lx-%lx}",
|
|
vnode->fid.vid, vnode->fid.vnode, first, last);
|
|
|
|
ASSERT(wb != NULL);
|
|
|
|
pagevec_init(&pv, 0);
|
|
|
|
do {
|
|
_debug("done %lx-%lx", first, last);
|
|
|
|
count = last - first + 1;
|
|
if (count > PAGEVEC_SIZE)
|
|
count = PAGEVEC_SIZE;
|
|
pv.nr = find_get_pages_contig(call->mapping, first, count,
|
|
pv.pages);
|
|
ASSERTCMP(pv.nr, ==, count);
|
|
|
|
spin_lock(&vnode->writeback_lock);
|
|
for (loop = 0; loop < count; loop++) {
|
|
struct page *page = pv.pages[loop];
|
|
end_page_writeback(page);
|
|
if (page_private(page) == (unsigned long) wb) {
|
|
set_page_private(page, 0);
|
|
ClearPagePrivate(page);
|
|
wb->usage--;
|
|
}
|
|
}
|
|
free_wb = false;
|
|
if (wb->usage == 0) {
|
|
afs_unlink_writeback(wb);
|
|
free_wb = true;
|
|
}
|
|
spin_unlock(&vnode->writeback_lock);
|
|
first += count;
|
|
if (free_wb) {
|
|
afs_free_writeback(wb);
|
|
wb = NULL;
|
|
}
|
|
|
|
__pagevec_release(&pv);
|
|
} while (first <= last);
|
|
|
|
_leave("");
|
|
}
|
|
|
|
/*
|
|
* write to an AFS file
|
|
*/
|
|
ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
|
|
{
|
|
struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
|
|
ssize_t result;
|
|
size_t count = iov_iter_count(from);
|
|
|
|
_enter("{%x.%u},{%zu},",
|
|
vnode->fid.vid, vnode->fid.vnode, count);
|
|
|
|
if (IS_SWAPFILE(&vnode->vfs_inode)) {
|
|
printk(KERN_INFO
|
|
"AFS: Attempt to write to active swap file!\n");
|
|
return -EBUSY;
|
|
}
|
|
|
|
if (!count)
|
|
return 0;
|
|
|
|
result = generic_file_write_iter(iocb, from);
|
|
if (IS_ERR_VALUE(result)) {
|
|
_leave(" = %zd", result);
|
|
return result;
|
|
}
|
|
|
|
_leave(" = %zd", result);
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* flush the vnode to the fileserver
|
|
*/
|
|
int afs_writeback_all(struct afs_vnode *vnode)
|
|
{
|
|
struct address_space *mapping = vnode->vfs_inode.i_mapping;
|
|
struct writeback_control wbc = {
|
|
.sync_mode = WB_SYNC_ALL,
|
|
.nr_to_write = LONG_MAX,
|
|
.range_cyclic = 1,
|
|
};
|
|
int ret;
|
|
|
|
_enter("");
|
|
|
|
ret = mapping->a_ops->writepages(mapping, &wbc);
|
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
|
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* flush any dirty pages for this process, and check for write errors.
|
|
* - the return status from this call provides a reliable indication of
|
|
* whether any write errors occurred for this process.
|
|
*/
|
|
int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
|
|
{
|
|
struct inode *inode = file_inode(file);
|
|
struct afs_writeback *wb, *xwb;
|
|
struct afs_vnode *vnode = AFS_FS_I(inode);
|
|
int ret;
|
|
|
|
_enter("{%x:%u},{n=%pD},%d",
|
|
vnode->fid.vid, vnode->fid.vnode, file,
|
|
datasync);
|
|
|
|
ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
|
|
if (ret)
|
|
return ret;
|
|
mutex_lock(&inode->i_mutex);
|
|
|
|
/* use a writeback record as a marker in the queue - when this reaches
|
|
* the front of the queue, all the outstanding writes are either
|
|
* completed or rejected */
|
|
wb = kzalloc(sizeof(*wb), GFP_KERNEL);
|
|
if (!wb) {
|
|
ret = -ENOMEM;
|
|
goto out;
|
|
}
|
|
wb->vnode = vnode;
|
|
wb->first = 0;
|
|
wb->last = -1;
|
|
wb->offset_first = 0;
|
|
wb->to_last = PAGE_SIZE;
|
|
wb->usage = 1;
|
|
wb->state = AFS_WBACK_SYNCING;
|
|
init_waitqueue_head(&wb->waitq);
|
|
|
|
spin_lock(&vnode->writeback_lock);
|
|
list_for_each_entry(xwb, &vnode->writebacks, link) {
|
|
if (xwb->state == AFS_WBACK_PENDING)
|
|
xwb->state = AFS_WBACK_CONFLICTING;
|
|
}
|
|
list_add_tail(&wb->link, &vnode->writebacks);
|
|
spin_unlock(&vnode->writeback_lock);
|
|
|
|
/* push all the outstanding writebacks to the server */
|
|
ret = afs_writeback_all(vnode);
|
|
if (ret < 0) {
|
|
afs_put_writeback(wb);
|
|
_leave(" = %d [wb]", ret);
|
|
goto out;
|
|
}
|
|
|
|
/* wait for the preceding writes to actually complete */
|
|
ret = wait_event_interruptible(wb->waitq,
|
|
wb->state == AFS_WBACK_COMPLETE ||
|
|
vnode->writebacks.next == &wb->link);
|
|
afs_put_writeback(wb);
|
|
_leave(" = %d", ret);
|
|
out:
|
|
mutex_unlock(&inode->i_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
|
|
|
|
_enter("{{%x:%u}},{%lx}",
|
|
vnode->fid.vid, vnode->fid.vnode, page->index);
|
|
|
|
/* wait for the page to be written to the cache before we allow it to
|
|
* be modified */
|
|
#ifdef CONFIG_AFS_FSCACHE
|
|
fscache_wait_on_page_write(vnode->cache, page);
|
|
#endif
|
|
|
|
_leave(" = 0");
|
|
return 0;
|
|
}
|