117 строки
3.2 KiB
C
117 строки
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Cache data I/O routines
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*
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* Copyright (C) 2021 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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#define FSCACHE_DEBUG_LEVEL PAGE
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#include <linux/module.h>
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#define FSCACHE_USE_NEW_IO_API
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#include <linux/fscache-cache.h>
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#include <linux/slab.h>
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#include <linux/netfs.h>
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#include "internal.h"
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/*
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* Start a cache read operation.
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* - we return:
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* -ENOMEM - out of memory, some pages may be being read
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* -ERESTARTSYS - interrupted, some pages may be being read
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* -ENOBUFS - no backing object or space available in which to cache any
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* pages not being read
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* -ENODATA - no data available in the backing object for some or all of
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* the pages
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* 0 - dispatched a read on all pages
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*/
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int __fscache_begin_read_operation(struct netfs_read_request *rreq,
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struct fscache_cookie *cookie)
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{
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struct fscache_retrieval *op;
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struct fscache_object *object;
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bool wake_cookie = false;
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int ret;
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_enter("rr=%08x", rreq->debug_id);
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fscache_stat(&fscache_n_retrievals);
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if (hlist_empty(&cookie->backing_objects))
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goto nobufs;
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if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
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_leave(" = -ENOBUFS [invalidating]");
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return -ENOBUFS;
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}
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ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
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if (fscache_wait_for_deferred_lookup(cookie) < 0)
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return -ERESTARTSYS;
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op = fscache_alloc_retrieval(cookie, NULL, NULL, NULL);
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if (!op)
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return -ENOMEM;
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trace_fscache_page_op(cookie, NULL, &op->op, fscache_page_op_retr_multi);
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spin_lock(&cookie->lock);
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if (!fscache_cookie_enabled(cookie) ||
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hlist_empty(&cookie->backing_objects))
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goto nobufs_unlock;
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object = hlist_entry(cookie->backing_objects.first,
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struct fscache_object, cookie_link);
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__fscache_use_cookie(cookie);
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atomic_inc(&object->n_reads);
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__set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
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if (fscache_submit_op(object, &op->op) < 0)
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goto nobufs_unlock_dec;
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spin_unlock(&cookie->lock);
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fscache_stat(&fscache_n_retrieval_ops);
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/* we wait for the operation to become active, and then process it
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* *here*, in this thread, and not in the thread pool */
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ret = fscache_wait_for_operation_activation(
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object, &op->op,
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__fscache_stat(&fscache_n_retrieval_op_waits),
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__fscache_stat(&fscache_n_retrievals_object_dead));
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if (ret < 0)
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goto error;
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/* ask the cache to honour the operation */
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ret = object->cache->ops->begin_read_operation(rreq, op);
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error:
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if (ret == -ENOMEM)
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fscache_stat(&fscache_n_retrievals_nomem);
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else if (ret == -ERESTARTSYS)
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fscache_stat(&fscache_n_retrievals_intr);
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else if (ret == -ENODATA)
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fscache_stat(&fscache_n_retrievals_nodata);
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else if (ret < 0)
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fscache_stat(&fscache_n_retrievals_nobufs);
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else
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fscache_stat(&fscache_n_retrievals_ok);
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fscache_put_retrieval(op);
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_leave(" = %d", ret);
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return ret;
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nobufs_unlock_dec:
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atomic_dec(&object->n_reads);
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wake_cookie = __fscache_unuse_cookie(cookie);
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nobufs_unlock:
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spin_unlock(&cookie->lock);
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fscache_put_retrieval(op);
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if (wake_cookie)
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__fscache_wake_unused_cookie(cookie);
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nobufs:
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fscache_stat(&fscache_n_retrievals_nobufs);
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_leave(" = -ENOBUFS");
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return -ENOBUFS;
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}
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EXPORT_SYMBOL(__fscache_begin_read_operation);
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