![Colin Ian King](/assets/img/avatar_default.png)
Variable 'cache' is being assigned but is never used hence it is redundant and can be removed. Cleans up clang warning: warning: variable 'cache' set but not used [-Wunused-but-set-variable] Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: David Howells <dhowells@redhat.com>
978 lines
24 KiB
C
978 lines
24 KiB
C
/* Storage object read/write
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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 Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/mount.h>
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#include <linux/slab.h>
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#include <linux/file.h>
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#include <linux/swap.h>
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#include "internal.h"
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/*
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* detect wake up events generated by the unlocking of pages in which we're
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* interested
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* - we use this to detect read completion of backing pages
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* - the caller holds the waitqueue lock
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*/
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static int cachefiles_read_waiter(wait_queue_entry_t *wait, unsigned mode,
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int sync, void *_key)
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{
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struct cachefiles_one_read *monitor =
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container_of(wait, struct cachefiles_one_read, monitor);
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struct cachefiles_object *object;
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struct fscache_retrieval *op = monitor->op;
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struct wait_bit_key *key = _key;
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struct page *page = wait->private;
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ASSERT(key);
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_enter("{%lu},%u,%d,{%p,%u}",
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monitor->netfs_page->index, mode, sync,
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key->flags, key->bit_nr);
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if (key->flags != &page->flags ||
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key->bit_nr != PG_locked)
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return 0;
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_debug("--- monitor %p %lx ---", page, page->flags);
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if (!PageUptodate(page) && !PageError(page)) {
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/* unlocked, not uptodate and not erronous? */
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_debug("page probably truncated");
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}
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/* remove from the waitqueue */
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list_del(&wait->entry);
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/* move onto the action list and queue for FS-Cache thread pool */
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ASSERT(op);
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/* We need to temporarily bump the usage count as we don't own a ref
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* here otherwise cachefiles_read_copier() may free the op between the
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* monitor being enqueued on the op->to_do list and the op getting
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* enqueued on the work queue.
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*/
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fscache_get_retrieval(op);
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object = container_of(op->op.object, struct cachefiles_object, fscache);
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spin_lock(&object->work_lock);
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list_add_tail(&monitor->op_link, &op->to_do);
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spin_unlock(&object->work_lock);
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fscache_enqueue_retrieval(op);
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fscache_put_retrieval(op);
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return 0;
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}
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/*
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* handle a probably truncated page
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* - check to see if the page is still relevant and reissue the read if
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* possible
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* - return -EIO on error, -ENODATA if the page is gone, -EINPROGRESS if we
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* must wait again and 0 if successful
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*/
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static int cachefiles_read_reissue(struct cachefiles_object *object,
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struct cachefiles_one_read *monitor)
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{
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struct address_space *bmapping = d_backing_inode(object->backer)->i_mapping;
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struct page *backpage = monitor->back_page, *backpage2;
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int ret;
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_enter("{ino=%lx},{%lx,%lx}",
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d_backing_inode(object->backer)->i_ino,
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backpage->index, backpage->flags);
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/* skip if the page was truncated away completely */
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if (backpage->mapping != bmapping) {
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_leave(" = -ENODATA [mapping]");
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return -ENODATA;
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}
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backpage2 = find_get_page(bmapping, backpage->index);
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if (!backpage2) {
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_leave(" = -ENODATA [gone]");
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return -ENODATA;
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}
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if (backpage != backpage2) {
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put_page(backpage2);
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_leave(" = -ENODATA [different]");
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return -ENODATA;
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}
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/* the page is still there and we already have a ref on it, so we don't
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* need a second */
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put_page(backpage2);
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INIT_LIST_HEAD(&monitor->op_link);
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add_page_wait_queue(backpage, &monitor->monitor);
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if (trylock_page(backpage)) {
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ret = -EIO;
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if (PageError(backpage))
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goto unlock_discard;
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ret = 0;
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if (PageUptodate(backpage))
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goto unlock_discard;
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_debug("reissue read");
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ret = bmapping->a_ops->readpage(NULL, backpage);
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if (ret < 0)
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goto unlock_discard;
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}
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/* but the page may have been read before the monitor was installed, so
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* the monitor may miss the event - so we have to ensure that we do get
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* one in such a case */
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if (trylock_page(backpage)) {
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_debug("jumpstart %p {%lx}", backpage, backpage->flags);
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unlock_page(backpage);
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}
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/* it'll reappear on the todo list */
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_leave(" = -EINPROGRESS");
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return -EINPROGRESS;
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unlock_discard:
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unlock_page(backpage);
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spin_lock_irq(&object->work_lock);
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list_del(&monitor->op_link);
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spin_unlock_irq(&object->work_lock);
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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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* copy data from backing pages to netfs pages to complete a read operation
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* - driven by FS-Cache's thread pool
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*/
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static void cachefiles_read_copier(struct fscache_operation *_op)
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{
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struct cachefiles_one_read *monitor;
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struct cachefiles_object *object;
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struct fscache_retrieval *op;
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int error, max;
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op = container_of(_op, struct fscache_retrieval, op);
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object = container_of(op->op.object,
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struct cachefiles_object, fscache);
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_enter("{ino=%lu}", d_backing_inode(object->backer)->i_ino);
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max = 8;
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spin_lock_irq(&object->work_lock);
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while (!list_empty(&op->to_do)) {
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monitor = list_entry(op->to_do.next,
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struct cachefiles_one_read, op_link);
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list_del(&monitor->op_link);
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spin_unlock_irq(&object->work_lock);
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_debug("- copy {%lu}", monitor->back_page->index);
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recheck:
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if (test_bit(FSCACHE_COOKIE_INVALIDATING,
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&object->fscache.cookie->flags)) {
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error = -ESTALE;
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} else if (PageUptodate(monitor->back_page)) {
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copy_highpage(monitor->netfs_page, monitor->back_page);
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fscache_mark_page_cached(monitor->op,
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monitor->netfs_page);
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error = 0;
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} else if (!PageError(monitor->back_page)) {
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/* the page has probably been truncated */
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error = cachefiles_read_reissue(object, monitor);
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if (error == -EINPROGRESS)
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goto next;
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goto recheck;
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} else {
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cachefiles_io_error_obj(
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object,
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"Readpage failed on backing file %lx",
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(unsigned long) monitor->back_page->flags);
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error = -EIO;
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}
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put_page(monitor->back_page);
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fscache_end_io(op, monitor->netfs_page, error);
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put_page(monitor->netfs_page);
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fscache_retrieval_complete(op, 1);
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fscache_put_retrieval(op);
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kfree(monitor);
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next:
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/* let the thread pool have some air occasionally */
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max--;
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if (max < 0 || need_resched()) {
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if (!list_empty(&op->to_do))
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fscache_enqueue_retrieval(op);
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_leave(" [maxed out]");
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return;
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}
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spin_lock_irq(&object->work_lock);
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}
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spin_unlock_irq(&object->work_lock);
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_leave("");
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}
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/*
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* read the corresponding page to the given set from the backing file
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* - an uncertain page is simply discarded, to be tried again another time
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*/
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static int cachefiles_read_backing_file_one(struct cachefiles_object *object,
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struct fscache_retrieval *op,
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struct page *netpage)
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{
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struct cachefiles_one_read *monitor;
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struct address_space *bmapping;
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struct page *newpage, *backpage;
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int ret;
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_enter("");
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_debug("read back %p{%lu,%d}",
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netpage, netpage->index, page_count(netpage));
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monitor = kzalloc(sizeof(*monitor), cachefiles_gfp);
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if (!monitor)
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goto nomem;
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monitor->netfs_page = netpage;
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monitor->op = fscache_get_retrieval(op);
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init_waitqueue_func_entry(&monitor->monitor, cachefiles_read_waiter);
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/* attempt to get hold of the backing page */
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bmapping = d_backing_inode(object->backer)->i_mapping;
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newpage = NULL;
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for (;;) {
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backpage = find_get_page(bmapping, netpage->index);
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if (backpage)
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goto backing_page_already_present;
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if (!newpage) {
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newpage = __page_cache_alloc(cachefiles_gfp);
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if (!newpage)
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goto nomem_monitor;
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}
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ret = add_to_page_cache_lru(newpage, bmapping,
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netpage->index, cachefiles_gfp);
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if (ret == 0)
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goto installed_new_backing_page;
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if (ret != -EEXIST)
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goto nomem_page;
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}
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/* we've installed a new backing page, so now we need to start
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* it reading */
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installed_new_backing_page:
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_debug("- new %p", newpage);
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backpage = newpage;
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newpage = NULL;
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read_backing_page:
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ret = bmapping->a_ops->readpage(NULL, backpage);
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if (ret < 0)
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goto read_error;
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/* set the monitor to transfer the data across */
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monitor_backing_page:
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_debug("- monitor add");
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/* install the monitor */
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get_page(monitor->netfs_page);
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get_page(backpage);
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monitor->back_page = backpage;
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monitor->monitor.private = backpage;
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add_page_wait_queue(backpage, &monitor->monitor);
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monitor = NULL;
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/* but the page may have been read before the monitor was installed, so
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* the monitor may miss the event - so we have to ensure that we do get
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* one in such a case */
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if (trylock_page(backpage)) {
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_debug("jumpstart %p {%lx}", backpage, backpage->flags);
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unlock_page(backpage);
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}
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goto success;
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/* if the backing page is already present, it can be in one of
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* three states: read in progress, read failed or read okay */
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backing_page_already_present:
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_debug("- present");
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if (newpage) {
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put_page(newpage);
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newpage = NULL;
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}
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if (PageError(backpage))
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goto io_error;
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if (PageUptodate(backpage))
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goto backing_page_already_uptodate;
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if (!trylock_page(backpage))
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goto monitor_backing_page;
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_debug("read %p {%lx}", backpage, backpage->flags);
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goto read_backing_page;
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/* the backing page is already up to date, attach the netfs
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* page to the pagecache and LRU and copy the data across */
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backing_page_already_uptodate:
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_debug("- uptodate");
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fscache_mark_page_cached(op, netpage);
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copy_highpage(netpage, backpage);
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fscache_end_io(op, netpage, 0);
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fscache_retrieval_complete(op, 1);
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success:
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_debug("success");
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ret = 0;
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out:
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if (backpage)
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put_page(backpage);
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if (monitor) {
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fscache_put_retrieval(monitor->op);
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kfree(monitor);
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}
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_leave(" = %d", ret);
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return ret;
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read_error:
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_debug("read error %d", ret);
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if (ret == -ENOMEM) {
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fscache_retrieval_complete(op, 1);
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goto out;
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}
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io_error:
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cachefiles_io_error_obj(object, "Page read error on backing file");
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fscache_retrieval_complete(op, 1);
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ret = -ENOBUFS;
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goto out;
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nomem_page:
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put_page(newpage);
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nomem_monitor:
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fscache_put_retrieval(monitor->op);
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kfree(monitor);
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nomem:
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fscache_retrieval_complete(op, 1);
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_leave(" = -ENOMEM");
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return -ENOMEM;
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}
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/*
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* read a page from the cache or allocate a block in which to store it
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* - cache withdrawal is prevented by the caller
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* - returns -EINTR if interrupted
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* - returns -ENOMEM if ran out of memory
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* - returns -ENOBUFS if no buffers can be made available
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* - returns -ENOBUFS if page is beyond EOF
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* - if the page is backed by a block in the cache:
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* - a read will be started which will call the callback on completion
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* - 0 will be returned
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* - else if the page is unbacked:
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* - the metadata will be retained
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* - -ENODATA will be returned
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*/
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int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
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struct page *page,
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gfp_t gfp)
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{
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struct cachefiles_object *object;
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struct cachefiles_cache *cache;
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struct inode *inode;
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sector_t block0, block;
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unsigned shift;
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int ret;
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object = container_of(op->op.object,
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struct cachefiles_object, fscache);
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cache = container_of(object->fscache.cache,
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struct cachefiles_cache, cache);
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_enter("{%p},{%lx},,,", object, page->index);
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if (!object->backer)
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goto enobufs;
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inode = d_backing_inode(object->backer);
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ASSERT(S_ISREG(inode->i_mode));
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ASSERT(inode->i_mapping->a_ops->bmap);
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ASSERT(inode->i_mapping->a_ops->readpages);
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/* calculate the shift required to use bmap */
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shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
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op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
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op->op.flags |= FSCACHE_OP_ASYNC;
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op->op.processor = cachefiles_read_copier;
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/* we assume the absence or presence of the first block is a good
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* enough indication for the page as a whole
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* - TODO: don't use bmap() for this as it is _not_ actually good
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* enough for this as it doesn't indicate errors, but it's all we've
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* got for the moment
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*/
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block0 = page->index;
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block0 <<= shift;
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block = inode->i_mapping->a_ops->bmap(inode->i_mapping, block0);
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_debug("%llx -> %llx",
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(unsigned long long) block0,
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(unsigned long long) block);
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if (block) {
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/* submit the apparently valid page to the backing fs to be
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* read from disk */
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ret = cachefiles_read_backing_file_one(object, op, page);
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} else if (cachefiles_has_space(cache, 0, 1) == 0) {
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/* there's space in the cache we can use */
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fscache_mark_page_cached(op, page);
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fscache_retrieval_complete(op, 1);
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ret = -ENODATA;
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} else {
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goto enobufs;
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}
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_leave(" = %d", ret);
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return ret;
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enobufs:
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fscache_retrieval_complete(op, 1);
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_leave(" = -ENOBUFS");
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return -ENOBUFS;
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}
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/*
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* read the corresponding pages to the given set from the backing file
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* - any uncertain pages are simply discarded, to be tried again another time
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*/
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static int cachefiles_read_backing_file(struct cachefiles_object *object,
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struct fscache_retrieval *op,
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struct list_head *list)
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{
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struct cachefiles_one_read *monitor = NULL;
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struct address_space *bmapping = d_backing_inode(object->backer)->i_mapping;
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struct page *newpage = NULL, *netpage, *_n, *backpage = NULL;
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int ret = 0;
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_enter("");
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list_for_each_entry_safe(netpage, _n, list, lru) {
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list_del(&netpage->lru);
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_debug("read back %p{%lu,%d}",
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netpage, netpage->index, page_count(netpage));
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if (!monitor) {
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monitor = kzalloc(sizeof(*monitor), cachefiles_gfp);
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if (!monitor)
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goto nomem;
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monitor->op = fscache_get_retrieval(op);
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init_waitqueue_func_entry(&monitor->monitor,
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cachefiles_read_waiter);
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}
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for (;;) {
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backpage = find_get_page(bmapping, netpage->index);
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if (backpage)
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goto backing_page_already_present;
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if (!newpage) {
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newpage = __page_cache_alloc(cachefiles_gfp);
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if (!newpage)
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goto nomem;
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}
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ret = add_to_page_cache_lru(newpage, bmapping,
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netpage->index,
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cachefiles_gfp);
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if (ret == 0)
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goto installed_new_backing_page;
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if (ret != -EEXIST)
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goto nomem;
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}
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/* we've installed a new backing page, so now we need
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* to start it reading */
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installed_new_backing_page:
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_debug("- new %p", newpage);
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backpage = newpage;
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newpage = NULL;
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reread_backing_page:
|
|
ret = bmapping->a_ops->readpage(NULL, backpage);
|
|
if (ret < 0)
|
|
goto read_error;
|
|
|
|
/* add the netfs page to the pagecache and LRU, and set the
|
|
* monitor to transfer the data across */
|
|
monitor_backing_page:
|
|
_debug("- monitor add");
|
|
|
|
ret = add_to_page_cache_lru(netpage, op->mapping,
|
|
netpage->index, cachefiles_gfp);
|
|
if (ret < 0) {
|
|
if (ret == -EEXIST) {
|
|
put_page(backpage);
|
|
backpage = NULL;
|
|
put_page(netpage);
|
|
netpage = NULL;
|
|
fscache_retrieval_complete(op, 1);
|
|
continue;
|
|
}
|
|
goto nomem;
|
|
}
|
|
|
|
/* install a monitor */
|
|
get_page(netpage);
|
|
monitor->netfs_page = netpage;
|
|
|
|
get_page(backpage);
|
|
monitor->back_page = backpage;
|
|
monitor->monitor.private = backpage;
|
|
add_page_wait_queue(backpage, &monitor->monitor);
|
|
monitor = NULL;
|
|
|
|
/* but the page may have been read before the monitor was
|
|
* installed, so the monitor may miss the event - so we have to
|
|
* ensure that we do get one in such a case */
|
|
if (trylock_page(backpage)) {
|
|
_debug("2unlock %p {%lx}", backpage, backpage->flags);
|
|
unlock_page(backpage);
|
|
}
|
|
|
|
put_page(backpage);
|
|
backpage = NULL;
|
|
|
|
put_page(netpage);
|
|
netpage = NULL;
|
|
continue;
|
|
|
|
/* if the backing page is already present, it can be in one of
|
|
* three states: read in progress, read failed or read okay */
|
|
backing_page_already_present:
|
|
_debug("- present %p", backpage);
|
|
|
|
if (PageError(backpage))
|
|
goto io_error;
|
|
|
|
if (PageUptodate(backpage))
|
|
goto backing_page_already_uptodate;
|
|
|
|
_debug("- not ready %p{%lx}", backpage, backpage->flags);
|
|
|
|
if (!trylock_page(backpage))
|
|
goto monitor_backing_page;
|
|
|
|
if (PageError(backpage)) {
|
|
_debug("error %lx", backpage->flags);
|
|
unlock_page(backpage);
|
|
goto io_error;
|
|
}
|
|
|
|
if (PageUptodate(backpage))
|
|
goto backing_page_already_uptodate_unlock;
|
|
|
|
/* we've locked a page that's neither up to date nor erroneous,
|
|
* so we need to attempt to read it again */
|
|
goto reread_backing_page;
|
|
|
|
/* the backing page is already up to date, attach the netfs
|
|
* page to the pagecache and LRU and copy the data across */
|
|
backing_page_already_uptodate_unlock:
|
|
_debug("uptodate %lx", backpage->flags);
|
|
unlock_page(backpage);
|
|
backing_page_already_uptodate:
|
|
_debug("- uptodate");
|
|
|
|
ret = add_to_page_cache_lru(netpage, op->mapping,
|
|
netpage->index, cachefiles_gfp);
|
|
if (ret < 0) {
|
|
if (ret == -EEXIST) {
|
|
put_page(backpage);
|
|
backpage = NULL;
|
|
put_page(netpage);
|
|
netpage = NULL;
|
|
fscache_retrieval_complete(op, 1);
|
|
continue;
|
|
}
|
|
goto nomem;
|
|
}
|
|
|
|
copy_highpage(netpage, backpage);
|
|
|
|
put_page(backpage);
|
|
backpage = NULL;
|
|
|
|
fscache_mark_page_cached(op, netpage);
|
|
|
|
/* the netpage is unlocked and marked up to date here */
|
|
fscache_end_io(op, netpage, 0);
|
|
put_page(netpage);
|
|
netpage = NULL;
|
|
fscache_retrieval_complete(op, 1);
|
|
continue;
|
|
}
|
|
|
|
netpage = NULL;
|
|
|
|
_debug("out");
|
|
|
|
out:
|
|
/* tidy up */
|
|
if (newpage)
|
|
put_page(newpage);
|
|
if (netpage)
|
|
put_page(netpage);
|
|
if (backpage)
|
|
put_page(backpage);
|
|
if (monitor) {
|
|
fscache_put_retrieval(op);
|
|
kfree(monitor);
|
|
}
|
|
|
|
list_for_each_entry_safe(netpage, _n, list, lru) {
|
|
list_del(&netpage->lru);
|
|
put_page(netpage);
|
|
fscache_retrieval_complete(op, 1);
|
|
}
|
|
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
|
|
nomem:
|
|
_debug("nomem");
|
|
ret = -ENOMEM;
|
|
goto record_page_complete;
|
|
|
|
read_error:
|
|
_debug("read error %d", ret);
|
|
if (ret == -ENOMEM)
|
|
goto record_page_complete;
|
|
io_error:
|
|
cachefiles_io_error_obj(object, "Page read error on backing file");
|
|
ret = -ENOBUFS;
|
|
record_page_complete:
|
|
fscache_retrieval_complete(op, 1);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* read a list of pages from the cache or allocate blocks in which to store
|
|
* them
|
|
*/
|
|
int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
|
|
struct list_head *pages,
|
|
unsigned *nr_pages,
|
|
gfp_t gfp)
|
|
{
|
|
struct cachefiles_object *object;
|
|
struct cachefiles_cache *cache;
|
|
struct list_head backpages;
|
|
struct pagevec pagevec;
|
|
struct inode *inode;
|
|
struct page *page, *_n;
|
|
unsigned shift, nrbackpages;
|
|
int ret, ret2, space;
|
|
|
|
object = container_of(op->op.object,
|
|
struct cachefiles_object, fscache);
|
|
cache = container_of(object->fscache.cache,
|
|
struct cachefiles_cache, cache);
|
|
|
|
_enter("{OBJ%x,%d},,%d,,",
|
|
object->fscache.debug_id, atomic_read(&op->op.usage),
|
|
*nr_pages);
|
|
|
|
if (!object->backer)
|
|
goto all_enobufs;
|
|
|
|
space = 1;
|
|
if (cachefiles_has_space(cache, 0, *nr_pages) < 0)
|
|
space = 0;
|
|
|
|
inode = d_backing_inode(object->backer);
|
|
ASSERT(S_ISREG(inode->i_mode));
|
|
ASSERT(inode->i_mapping->a_ops->bmap);
|
|
ASSERT(inode->i_mapping->a_ops->readpages);
|
|
|
|
/* calculate the shift required to use bmap */
|
|
shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
|
|
|
|
pagevec_init(&pagevec);
|
|
|
|
op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
|
|
op->op.flags |= FSCACHE_OP_ASYNC;
|
|
op->op.processor = cachefiles_read_copier;
|
|
|
|
INIT_LIST_HEAD(&backpages);
|
|
nrbackpages = 0;
|
|
|
|
ret = space ? -ENODATA : -ENOBUFS;
|
|
list_for_each_entry_safe(page, _n, pages, lru) {
|
|
sector_t block0, block;
|
|
|
|
/* we assume the absence or presence of the first block is a
|
|
* good enough indication for the page as a whole
|
|
* - TODO: don't use bmap() for this as it is _not_ actually
|
|
* good enough for this as it doesn't indicate errors, but
|
|
* it's all we've got for the moment
|
|
*/
|
|
block0 = page->index;
|
|
block0 <<= shift;
|
|
|
|
block = inode->i_mapping->a_ops->bmap(inode->i_mapping,
|
|
block0);
|
|
_debug("%llx -> %llx",
|
|
(unsigned long long) block0,
|
|
(unsigned long long) block);
|
|
|
|
if (block) {
|
|
/* we have data - add it to the list to give to the
|
|
* backing fs */
|
|
list_move(&page->lru, &backpages);
|
|
(*nr_pages)--;
|
|
nrbackpages++;
|
|
} else if (space && pagevec_add(&pagevec, page) == 0) {
|
|
fscache_mark_pages_cached(op, &pagevec);
|
|
fscache_retrieval_complete(op, 1);
|
|
ret = -ENODATA;
|
|
} else {
|
|
fscache_retrieval_complete(op, 1);
|
|
}
|
|
}
|
|
|
|
if (pagevec_count(&pagevec) > 0)
|
|
fscache_mark_pages_cached(op, &pagevec);
|
|
|
|
if (list_empty(pages))
|
|
ret = 0;
|
|
|
|
/* submit the apparently valid pages to the backing fs to be read from
|
|
* disk */
|
|
if (nrbackpages > 0) {
|
|
ret2 = cachefiles_read_backing_file(object, op, &backpages);
|
|
if (ret2 == -ENOMEM || ret2 == -EINTR)
|
|
ret = ret2;
|
|
}
|
|
|
|
_leave(" = %d [nr=%u%s]",
|
|
ret, *nr_pages, list_empty(pages) ? " empty" : "");
|
|
return ret;
|
|
|
|
all_enobufs:
|
|
fscache_retrieval_complete(op, *nr_pages);
|
|
return -ENOBUFS;
|
|
}
|
|
|
|
/*
|
|
* allocate a block in the cache in which to store a page
|
|
* - cache withdrawal is prevented by the caller
|
|
* - returns -EINTR if interrupted
|
|
* - returns -ENOMEM if ran out of memory
|
|
* - returns -ENOBUFS if no buffers can be made available
|
|
* - returns -ENOBUFS if page is beyond EOF
|
|
* - otherwise:
|
|
* - the metadata will be retained
|
|
* - 0 will be returned
|
|
*/
|
|
int cachefiles_allocate_page(struct fscache_retrieval *op,
|
|
struct page *page,
|
|
gfp_t gfp)
|
|
{
|
|
struct cachefiles_object *object;
|
|
struct cachefiles_cache *cache;
|
|
int ret;
|
|
|
|
object = container_of(op->op.object,
|
|
struct cachefiles_object, fscache);
|
|
cache = container_of(object->fscache.cache,
|
|
struct cachefiles_cache, cache);
|
|
|
|
_enter("%p,{%lx},", object, page->index);
|
|
|
|
ret = cachefiles_has_space(cache, 0, 1);
|
|
if (ret == 0)
|
|
fscache_mark_page_cached(op, page);
|
|
else
|
|
ret = -ENOBUFS;
|
|
|
|
fscache_retrieval_complete(op, 1);
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* allocate blocks in the cache in which to store a set of pages
|
|
* - cache withdrawal is prevented by the caller
|
|
* - returns -EINTR if interrupted
|
|
* - returns -ENOMEM if ran out of memory
|
|
* - returns -ENOBUFS if some buffers couldn't be made available
|
|
* - returns -ENOBUFS if some pages are beyond EOF
|
|
* - otherwise:
|
|
* - -ENODATA will be returned
|
|
* - metadata will be retained for any page marked
|
|
*/
|
|
int cachefiles_allocate_pages(struct fscache_retrieval *op,
|
|
struct list_head *pages,
|
|
unsigned *nr_pages,
|
|
gfp_t gfp)
|
|
{
|
|
struct cachefiles_object *object;
|
|
struct cachefiles_cache *cache;
|
|
struct pagevec pagevec;
|
|
struct page *page;
|
|
int ret;
|
|
|
|
object = container_of(op->op.object,
|
|
struct cachefiles_object, fscache);
|
|
cache = container_of(object->fscache.cache,
|
|
struct cachefiles_cache, cache);
|
|
|
|
_enter("%p,,,%d,", object, *nr_pages);
|
|
|
|
ret = cachefiles_has_space(cache, 0, *nr_pages);
|
|
if (ret == 0) {
|
|
pagevec_init(&pagevec);
|
|
|
|
list_for_each_entry(page, pages, lru) {
|
|
if (pagevec_add(&pagevec, page) == 0)
|
|
fscache_mark_pages_cached(op, &pagevec);
|
|
}
|
|
|
|
if (pagevec_count(&pagevec) > 0)
|
|
fscache_mark_pages_cached(op, &pagevec);
|
|
ret = -ENODATA;
|
|
} else {
|
|
ret = -ENOBUFS;
|
|
}
|
|
|
|
fscache_retrieval_complete(op, *nr_pages);
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* request a page be stored in the cache
|
|
* - cache withdrawal is prevented by the caller
|
|
* - this request may be ignored if there's no cache block available, in which
|
|
* case -ENOBUFS will be returned
|
|
* - if the op is in progress, 0 will be returned
|
|
*/
|
|
int cachefiles_write_page(struct fscache_storage *op, struct page *page)
|
|
{
|
|
struct cachefiles_object *object;
|
|
struct cachefiles_cache *cache;
|
|
struct file *file;
|
|
struct path path;
|
|
loff_t pos, eof;
|
|
size_t len;
|
|
void *data;
|
|
int ret = -ENOBUFS;
|
|
|
|
ASSERT(op != NULL);
|
|
ASSERT(page != NULL);
|
|
|
|
object = container_of(op->op.object,
|
|
struct cachefiles_object, fscache);
|
|
|
|
_enter("%p,%p{%lx},,,", object, page, page->index);
|
|
|
|
if (!object->backer) {
|
|
_leave(" = -ENOBUFS");
|
|
return -ENOBUFS;
|
|
}
|
|
|
|
ASSERT(d_is_reg(object->backer));
|
|
|
|
cache = container_of(object->fscache.cache,
|
|
struct cachefiles_cache, cache);
|
|
|
|
pos = (loff_t)page->index << PAGE_SHIFT;
|
|
|
|
/* We mustn't write more data than we have, so we have to beware of a
|
|
* partial page at EOF.
|
|
*/
|
|
eof = object->fscache.store_limit_l;
|
|
if (pos >= eof)
|
|
goto error;
|
|
|
|
/* write the page to the backing filesystem and let it store it in its
|
|
* own time */
|
|
path.mnt = cache->mnt;
|
|
path.dentry = object->backer;
|
|
file = dentry_open(&path, O_RDWR | O_LARGEFILE, cache->cache_cred);
|
|
if (IS_ERR(file)) {
|
|
ret = PTR_ERR(file);
|
|
goto error_2;
|
|
}
|
|
|
|
len = PAGE_SIZE;
|
|
if (eof & ~PAGE_MASK) {
|
|
if (eof - pos < PAGE_SIZE) {
|
|
_debug("cut short %llx to %llx",
|
|
pos, eof);
|
|
len = eof - pos;
|
|
ASSERTCMP(pos + len, ==, eof);
|
|
}
|
|
}
|
|
|
|
data = kmap(page);
|
|
ret = __kernel_write(file, data, len, &pos);
|
|
kunmap(page);
|
|
fput(file);
|
|
if (ret != len)
|
|
goto error_eio;
|
|
|
|
_leave(" = 0");
|
|
return 0;
|
|
|
|
error_eio:
|
|
ret = -EIO;
|
|
error_2:
|
|
if (ret == -EIO)
|
|
cachefiles_io_error_obj(object,
|
|
"Write page to backing file failed");
|
|
error:
|
|
_leave(" = -ENOBUFS [%d]", ret);
|
|
return -ENOBUFS;
|
|
}
|
|
|
|
/*
|
|
* detach a backing block from a page
|
|
* - cache withdrawal is prevented by the caller
|
|
*/
|
|
void cachefiles_uncache_page(struct fscache_object *_object, struct page *page)
|
|
__releases(&object->fscache.cookie->lock)
|
|
{
|
|
struct cachefiles_object *object;
|
|
|
|
object = container_of(_object, struct cachefiles_object, fscache);
|
|
|
|
_enter("%p,{%lu}", object, page->index);
|
|
|
|
spin_unlock(&object->fscache.cookie->lock);
|
|
}
|