| David Howells | 26aaeff | 2021-02-22 11:39:47 +0000 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* Cache data I/O routines |
| 3 | * |
| 4 | * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. |
| 5 | * Written by David Howells (dhowells@redhat.com) |
| 6 | */ |
| 7 | |
| 8 | #define FSCACHE_DEBUG_LEVEL PAGE |
| 9 | #include <linux/module.h> |
| 10 | #define FSCACHE_USE_NEW_IO_API |
| 11 | #include <linux/fscache-cache.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <linux/netfs.h> |
| 14 | #include "internal.h" |
| 15 | |
| 16 | /* |
| 17 | * Start a cache read operation. |
| 18 | * - we return: |
| 19 | * -ENOMEM - out of memory, some pages may be being read |
| 20 | * -ERESTARTSYS - interrupted, some pages may be being read |
| 21 | * -ENOBUFS - no backing object or space available in which to cache any |
| 22 | * pages not being read |
| 23 | * -ENODATA - no data available in the backing object for some or all of |
| 24 | * the pages |
| 25 | * 0 - dispatched a read on all pages |
| 26 | */ |
| 27 | int __fscache_begin_read_operation(struct netfs_read_request *rreq, |
| 28 | struct fscache_cookie *cookie) |
| 29 | { |
| 30 | struct fscache_retrieval *op; |
| 31 | struct fscache_object *object; |
| 32 | bool wake_cookie = false; |
| 33 | int ret; |
| 34 | |
| 35 | _enter("rr=%08x", rreq->debug_id); |
| 36 | |
| 37 | fscache_stat(&fscache_n_retrievals); |
| 38 | |
| 39 | if (hlist_empty(&cookie->backing_objects)) |
| 40 | goto nobufs; |
| 41 | |
| 42 | if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { |
| 43 | _leave(" = -ENOBUFS [invalidating]"); |
| 44 | return -ENOBUFS; |
| 45 | } |
| 46 | |
| 47 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); |
| 48 | |
| 49 | if (fscache_wait_for_deferred_lookup(cookie) < 0) |
| 50 | return -ERESTARTSYS; |
| 51 | |
| 52 | op = fscache_alloc_retrieval(cookie, NULL, NULL, NULL); |
| 53 | if (!op) |
| 54 | return -ENOMEM; |
| 55 | trace_fscache_page_op(cookie, NULL, &op->op, fscache_page_op_retr_multi); |
| 56 | |
| 57 | spin_lock(&cookie->lock); |
| 58 | |
| 59 | if (!fscache_cookie_enabled(cookie) || |
| 60 | hlist_empty(&cookie->backing_objects)) |
| 61 | goto nobufs_unlock; |
| 62 | object = hlist_entry(cookie->backing_objects.first, |
| 63 | struct fscache_object, cookie_link); |
| 64 | |
| 65 | __fscache_use_cookie(cookie); |
| 66 | atomic_inc(&object->n_reads); |
| 67 | __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); |
| 68 | |
| 69 | if (fscache_submit_op(object, &op->op) < 0) |
| 70 | goto nobufs_unlock_dec; |
| 71 | spin_unlock(&cookie->lock); |
| 72 | |
| 73 | fscache_stat(&fscache_n_retrieval_ops); |
| 74 | |
| 75 | /* we wait for the operation to become active, and then process it |
| 76 | * *here*, in this thread, and not in the thread pool */ |
| 77 | ret = fscache_wait_for_operation_activation( |
| 78 | object, &op->op, |
| 79 | __fscache_stat(&fscache_n_retrieval_op_waits), |
| 80 | __fscache_stat(&fscache_n_retrievals_object_dead)); |
| 81 | if (ret < 0) |
| 82 | goto error; |
| 83 | |
| 84 | /* ask the cache to honour the operation */ |
| 85 | ret = object->cache->ops->begin_read_operation(rreq, op); |
| 86 | |
| 87 | error: |
| 88 | if (ret == -ENOMEM) |
| 89 | fscache_stat(&fscache_n_retrievals_nomem); |
| 90 | else if (ret == -ERESTARTSYS) |
| 91 | fscache_stat(&fscache_n_retrievals_intr); |
| 92 | else if (ret == -ENODATA) |
| 93 | fscache_stat(&fscache_n_retrievals_nodata); |
| 94 | else if (ret < 0) |
| 95 | fscache_stat(&fscache_n_retrievals_nobufs); |
| 96 | else |
| 97 | fscache_stat(&fscache_n_retrievals_ok); |
| 98 | |
| 99 | fscache_put_retrieval(op); |
| 100 | _leave(" = %d", ret); |
| 101 | return ret; |
| 102 | |
| 103 | nobufs_unlock_dec: |
| 104 | atomic_dec(&object->n_reads); |
| 105 | wake_cookie = __fscache_unuse_cookie(cookie); |
| 106 | nobufs_unlock: |
| 107 | spin_unlock(&cookie->lock); |
| 108 | fscache_put_retrieval(op); |
| 109 | if (wake_cookie) |
| 110 | __fscache_wake_unused_cookie(cookie); |
| 111 | nobufs: |
| 112 | fscache_stat(&fscache_n_retrievals_nobufs); |
| 113 | _leave(" = -ENOBUFS"); |
| 114 | return -ENOBUFS; |
| 115 | } |
| 116 | EXPORT_SYMBOL(__fscache_begin_read_operation); |