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116 lines
3.2 KiB
116 lines
3.2 KiB
// 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 ([email protected]) |
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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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