/* Cache page management and data I/O routines * * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #define FSCACHE_DEBUG_LEVEL PAGE #include <linux/module.h> #include <linux/fscache-cache.h> #include <linux/buffer_head.h> #include <linux/pagevec.h> #include <linux/slab.h> #include "internal.h" /* * check to see if a page is being written to the cache */ bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page) { void *val; rcu_read_lock(); val = radix_tree_lookup(&cookie->stores, page->index); rcu_read_unlock(); return val != NULL; } EXPORT_SYMBOL(__fscache_check_page_write); /* * wait for a page to finish being written to the cache */ void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page) { wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0); wait_event(*wq, !__fscache_check_page_write(cookie, page)); } EXPORT_SYMBOL(__fscache_wait_on_page_write); /* * decide whether a page can be released, possibly by cancelling a store to it * - we're allowed to sleep if __GFP_WAIT is flagged */ bool __fscache_maybe_release_page(struct fscache_cookie *cookie, struct page *page, gfp_t gfp) { struct page *xpage; void *val; _enter("%p,%p,%x", cookie, page, gfp); try_again: rcu_read_lock(); val = radix_tree_lookup(&cookie->stores, page->index); if (!val) { rcu_read_unlock(); fscache_stat(&fscache_n_store_vmscan_not_storing); __fscache_uncache_page(cookie, page); return true; } /* see if the page is actually undergoing storage - if so we can't get * rid of it till the cache has finished with it */ if (radix_tree_tag_get(&cookie->stores, page->index, FSCACHE_COOKIE_STORING_TAG)) { rcu_read_unlock(); goto page_busy; } /* the page is pending storage, so we attempt to cancel the store and * discard the store request so that the page can be reclaimed */ spin_lock(&cookie->stores_lock); rcu_read_unlock(); if (radix_tree_tag_get(&cookie->stores, page->index, FSCACHE_COOKIE_STORING_TAG)) { /* the page started to undergo storage whilst we were looking, * so now we can only wait or return */ spin_unlock(&cookie->stores_lock); goto page_busy; } xpage = radix_tree_delete(&cookie->stores, page->index); spin_unlock(&cookie->stores_lock); if (xpage) { fscache_stat(&fscache_n_store_vmscan_cancelled); fscache_stat(&fscache_n_store_radix_deletes); ASSERTCMP(xpage, ==, page); } else { fscache_stat(&fscache_n_store_vmscan_gone); } wake_up_bit(&cookie->flags, 0); if (xpage) page_cache_release(xpage); __fscache_uncache_page(cookie, page); return true; page_busy: /* We will wait here if we're allowed to, but that could deadlock the * allocator as the work threads writing to the cache may all end up * sleeping on memory allocation, so we may need to impose a timeout * too. */ if (!(gfp & __GFP_WAIT) || !(gfp & __GFP_FS)) { fscache_stat(&fscache_n_store_vmscan_busy); return false; } fscache_stat(&fscache_n_store_vmscan_wait); __fscache_wait_on_page_write(cookie, page); gfp &= ~__GFP_WAIT; goto try_again; } EXPORT_SYMBOL(__fscache_maybe_release_page); /* * note that a page has finished being written to the cache */ static void fscache_end_page_write(struct fscache_object *object, struct page *page) { struct fscache_cookie *cookie; struct page *xpage = NULL; spin_lock(&object->lock); cookie = object->cookie; if (cookie) { /* delete the page from the tree if it is now no longer * pending */ spin_lock(&cookie->stores_lock); radix_tree_tag_clear(&cookie->stores, page->index, FSCACHE_COOKIE_STORING_TAG); if (!radix_tree_tag_get(&cookie->stores, page->index, FSCACHE_COOKIE_PENDING_TAG)) { fscache_stat(&fscache_n_store_radix_deletes); xpage = radix_tree_delete(&cookie->stores, page->index); } spin_unlock(&cookie->stores_lock); wake_up_bit(&cookie->flags, 0); } spin_unlock(&object->lock); if (xpage) page_cache_release(xpage); } /* * actually apply the changed attributes to a cache object */ static void fscache_attr_changed_op(struct fscache_operation *op) { struct fscache_object *object = op->object; int ret; _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id); fscache_stat(&fscache_n_attr_changed_calls); if (fscache_object_is_active(object) && fscache_use_cookie(object)) { fscache_stat(&fscache_n_cop_attr_changed); ret = object->cache->ops->attr_changed(object); fscache_stat_d(&fscache_n_cop_attr_changed); fscache_unuse_cookie(object); if (ret < 0) fscache_abort_object(object); } fscache_op_complete(op, true); _leave(""); } /* * notification that the attributes on an object have changed */ int __fscache_attr_changed(struct fscache_cookie *cookie) { struct fscache_operation *op; struct fscache_object *object; _enter("%p", cookie); ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); fscache_stat(&fscache_n_attr_changed); op = kzalloc(sizeof(*op), GFP_KERNEL); if (!op) { fscache_stat(&fscache_n_attr_changed_nomem); _leave(" = -ENOMEM"); return -ENOMEM; } fscache_operation_init(op, fscache_attr_changed_op, NULL); op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE); spin_lock(&cookie->lock); if (hlist_empty(&cookie->backing_objects)) goto nobufs; object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); if (fscache_submit_exclusive_op(object, op) < 0) goto nobufs; spin_unlock(&cookie->lock); fscache_stat(&fscache_n_attr_changed_ok); fscache_put_operation(op); _leave(" = 0"); return 0; nobufs: spin_unlock(&cookie->lock); kfree(op); fscache_stat(&fscache_n_attr_changed_nobufs); _leave(" = %d", -ENOBUFS); return -ENOBUFS; } EXPORT_SYMBOL(__fscache_attr_changed); /* * release a retrieval op reference */ static void fscache_release_retrieval_op(struct fscache_operation *_op) { struct fscache_retrieval *op = container_of(_op, struct fscache_retrieval, op); _enter("{OP%x}", op->op.debug_id); ASSERTCMP(atomic_read(&op->n_pages), ==, 0); fscache_hist(fscache_retrieval_histogram, op->start_time); if (op->context) fscache_put_context(op->op.object->cookie, op->context); _leave(""); } /* * allocate a retrieval op */ static struct fscache_retrieval *fscache_alloc_retrieval( struct fscache_cookie *cookie, struct address_space *mapping, fscache_rw_complete_t end_io_func, void *context) { struct fscache_retrieval *op; /* allocate a retrieval operation and attempt to submit it */ op = kzalloc(sizeof(*op), GFP_NOIO); if (!op) { fscache_stat(&fscache_n_retrievals_nomem); return NULL; } fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op); atomic_inc(&cookie->n_active); op->op.flags = FSCACHE_OP_MYTHREAD | (1UL << FSCACHE_OP_WAITING) | (1UL << FSCACHE_OP_UNUSE_COOKIE); op->mapping = mapping; op->end_io_func = end_io_func; op->context = context; op->start_time = jiffies; INIT_LIST_HEAD(&op->to_do); return op; } /* * wait for a deferred lookup to complete */ int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie) { unsigned long jif; _enter(""); if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) { _leave(" = 0 [imm]"); return 0; } fscache_stat(&fscache_n_retrievals_wait); jif = jiffies; if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP, fscache_wait_bit_interruptible, TASK_INTERRUPTIBLE) != 0) { fscache_stat(&fscache_n_retrievals_intr); _leave(" = -ERESTARTSYS"); return -ERESTARTSYS; } ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)); smp_rmb(); fscache_hist(fscache_retrieval_delay_histogram, jif); _leave(" = 0 [dly]"); return 0; } /* * Handle cancellation of a pending retrieval op */ static void fscache_do_cancel_retrieval(struct fscache_operation *_op) { struct fscache_retrieval *op = container_of(_op, struct fscache_retrieval, op); atomic_set(&op->n_pages, 0); } /* * wait for an object to become active (or dead) */ int fscache_wait_for_operation_activation(struct fscache_object *object, struct fscache_operation *op, atomic_t *stat_op_waits, atomic_t *stat_object_dead, void (*do_cancel)(struct fscache_operation *)) { int ret; if (!test_bit(FSCACHE_OP_WAITING, &op->flags)) goto check_if_dead; _debug(">>> WT"); if (stat_op_waits) fscache_stat(stat_op_waits); if (wait_on_bit(&op->flags, FSCACHE_OP_WAITING, fscache_wait_bit_interruptible, TASK_INTERRUPTIBLE) != 0) { ret = fscache_cancel_op(op, do_cancel); if (ret == 0) return -ERESTARTSYS; /* it's been removed from the pending queue by another party, * so we should get to run shortly */ wait_on_bit(&op->flags, FSCACHE_OP_WAITING, fscache_wait_bit, TASK_UNINTERRUPTIBLE); } _debug("<<< GO"); check_if_dead: if (op->state == FSCACHE_OP_ST_CANCELLED) { if (stat_object_dead) fscache_stat(stat_object_dead); _leave(" = -ENOBUFS [cancelled]"); return -ENOBUFS; } if (unlikely(fscache_object_is_dead(object))) { pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->state); fscache_cancel_op(op, do_cancel); if (stat_object_dead) fscache_stat(stat_object_dead); return -ENOBUFS; } return 0; } /* * read a page from the cache or allocate a block in which to store it * - we return: * -ENOMEM - out of memory, nothing done * -ERESTARTSYS - interrupted * -ENOBUFS - no backing object available in which to cache the block * -ENODATA - no data available in the backing object for this block * 0 - dispatched a read - it'll call end_io_func() when finished */ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, struct page *page, fscache_rw_complete_t end_io_func, void *context, gfp_t gfp) { struct fscache_retrieval *op; struct fscache_object *object; int ret; _enter("%p,%p,,,", cookie, page); fscache_stat(&fscache_n_retrievals); if (hlist_empty(&cookie->backing_objects)) goto nobufs; if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { _leave(" = -ENOBUFS [invalidating]"); return -ENOBUFS; } ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); ASSERTCMP(page, !=, NULL); if (fscache_wait_for_deferred_lookup(cookie) < 0) return -ERESTARTSYS; op = fscache_alloc_retrieval(cookie, page->mapping, end_io_func,context); if (!op) { _leave(" = -ENOMEM"); return -ENOMEM; } atomic_set(&op->n_pages, 1); spin_lock(&cookie->lock); if (hlist_empty(&cookie->backing_objects)) goto nobufs_unlock; object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); ASSERT(test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)); atomic_inc(&object->n_reads); __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); if (fscache_submit_op(object, &op->op) < 0) goto nobufs_unlock_dec; spin_unlock(&cookie->lock); fscache_stat(&fscache_n_retrieval_ops); /* pin the netfs read context in case we need to do the actual netfs * read because we've encountered a cache read failure */ fscache_get_context(object->cookie, op->context); /* we wait for the operation to become active, and then process it * *here*, in this thread, and not in the thread pool */ ret = fscache_wait_for_operation_activation( object, &op->op, __fscache_stat(&fscache_n_retrieval_op_waits), __fscache_stat(&fscache_n_retrievals_object_dead), fscache_do_cancel_retrieval); if (ret < 0) goto error; /* ask the cache to honour the operation */ if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) { fscache_stat(&fscache_n_cop_allocate_page); ret = object->cache->ops->allocate_page(op, page, gfp); fscache_stat_d(&fscache_n_cop_allocate_page); if (ret == 0) ret = -ENODATA; } else { fscache_stat(&fscache_n_cop_read_or_alloc_page); ret = object->cache->ops->read_or_alloc_page(op, page, gfp); fscache_stat_d(&fscache_n_cop_read_or_alloc_page); } error: if (ret == -ENOMEM) fscache_stat(&fscache_n_retrievals_nomem); else if (ret == -ERESTARTSYS) fscache_stat(&fscache_n_retrievals_intr); else if (ret == -ENODATA) fscache_stat(&fscache_n_retrievals_nodata); else if (ret < 0) fscache_stat(&fscache_n_retrievals_nobufs); else fscache_stat(&fscache_n_retrievals_ok); fscache_put_retrieval(op); _leave(" = %d", ret); return ret; nobufs_unlock_dec: atomic_dec(&object->n_reads); nobufs_unlock: spin_unlock(&cookie->lock); atomic_dec(&cookie->n_active); kfree(op); nobufs: fscache_stat(&fscache_n_retrievals_nobufs); _leave(" = -ENOBUFS"); return -ENOBUFS; } EXPORT_SYMBOL(__fscache_read_or_alloc_page); /* * read a list of page from the cache or allocate a block in which to store * them * - we return: * -ENOMEM - out of memory, some pages may be being read * -ERESTARTSYS - interrupted, some pages may be being read * -ENOBUFS - no backing object or space available in which to cache any * pages not being read * -ENODATA - no data available in the backing object for some or all of * the pages * 0 - dispatched a read on all pages * * end_io_func() will be called for each page read from the cache as it is * finishes being read * * any pages for which a read is dispatched will be removed from pages and * nr_pages */ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, struct address_space *mapping, struct list_head *pages, unsigned *nr_pages, fscache_rw_complete_t end_io_func, void *context, gfp_t gfp) { struct fscache_retrieval *op; struct fscache_object *object; int ret; _enter("%p,,%d,,,", cookie, *nr_pages); fscache_stat(&fscache_n_retrievals); if (hlist_empty(&cookie->backing_objects)) goto nobufs; if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { _leave(" = -ENOBUFS [invalidating]"); return -ENOBUFS; } ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); ASSERTCMP(*nr_pages, >, 0); ASSERT(!list_empty(pages)); if (fscache_wait_for_deferred_lookup(cookie) < 0) return -ERESTARTSYS; op = fscache_alloc_retrieval(cookie, mapping, end_io_func, context); if (!op) return -ENOMEM; atomic_set(&op->n_pages, *nr_pages); spin_lock(&cookie->lock); if (hlist_empty(&cookie->backing_objects)) goto nobufs_unlock; object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); atomic_inc(&object->n_reads); __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); if (fscache_submit_op(object, &op->op) < 0) goto nobufs_unlock_dec; spin_unlock(&cookie->lock); fscache_stat(&fscache_n_retrieval_ops); /* pin the netfs read context in case we need to do the actual netfs * read because we've encountered a cache read failure */ fscache_get_context(object->cookie, op->context); /* we wait for the operation to become active, and then process it * *here*, in this thread, and not in the thread pool */ ret = fscache_wait_for_operation_activation( object, &op->op, __fscache_stat(&fscache_n_retrieval_op_waits), __fscache_stat(&fscache_n_retrievals_object_dead), fscache_do_cancel_retrieval); if (ret < 0) goto error; /* ask the cache to honour the operation */ if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) { fscache_stat(&fscache_n_cop_allocate_pages); ret = object->cache->ops->allocate_pages( op, pages, nr_pages, gfp); fscache_stat_d(&fscache_n_cop_allocate_pages); } else { fscache_stat(&fscache_n_cop_read_or_alloc_pages); ret = object->cache->ops->read_or_alloc_pages( op, pages, nr_pages, gfp); fscache_stat_d(&fscache_n_cop_read_or_alloc_pages); } error: if (ret == -ENOMEM) fscache_stat(&fscache_n_retrievals_nomem); else if (ret == -ERESTARTSYS) fscache_stat(&fscache_n_retrievals_intr); else if (ret == -ENODATA) fscache_stat(&fscache_n_retrievals_nodata); else if (ret < 0) fscache_stat(&fscache_n_retrievals_nobufs); else fscache_stat(&fscache_n_retrievals_ok); fscache_put_retrieval(op); _leave(" = %d", ret); return ret; nobufs_unlock_dec: atomic_dec(&object->n_reads); nobufs_unlock: spin_unlock(&cookie->lock); atomic_dec(&cookie->n_active); kfree(op); nobufs: fscache_stat(&fscache_n_retrievals_nobufs); _leave(" = -ENOBUFS"); return -ENOBUFS; } EXPORT_SYMBOL(__fscache_read_or_alloc_pages); /* * allocate a block in the cache on which to store a page * - we return: * -ENOMEM - out of memory, nothing done * -ERESTARTSYS - interrupted * -ENOBUFS - no backing object available in which to cache the block * 0 - block allocated */ int __fscache_alloc_page(struct fscache_cookie *cookie, struct page *page, gfp_t gfp) { struct fscache_retrieval *op; struct fscache_object *object; int ret; _enter("%p,%p,,,", cookie, page); fscache_stat(&fscache_n_allocs); if (hlist_empty(&cookie->backing_objects)) goto nobufs; ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); ASSERTCMP(page, !=, NULL); if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { _leave(" = -ENOBUFS [invalidating]"); return -ENOBUFS; } if (fscache_wait_for_deferred_lookup(cookie) < 0) return -ERESTARTSYS; op = fscache_alloc_retrieval(cookie, page->mapping, NULL, NULL); if (!op) return -ENOMEM; atomic_set(&op->n_pages, 1); spin_lock(&cookie->lock); if (hlist_empty(&cookie->backing_objects)) goto nobufs_unlock; object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); if (fscache_submit_op(object, &op->op) < 0) goto nobufs_unlock; spin_unlock(&cookie->lock); fscache_stat(&fscache_n_alloc_ops); ret = fscache_wait_for_operation_activation( object, &op->op, __fscache_stat(&fscache_n_alloc_op_waits), __fscache_stat(&fscache_n_allocs_object_dead), fscache_do_cancel_retrieval); if (ret < 0) goto error; /* ask the cache to honour the operation */ fscache_stat(&fscache_n_cop_allocate_page); ret = object->cache->ops->allocate_page(op, page, gfp); fscache_stat_d(&fscache_n_cop_allocate_page); error: if (ret == -ERESTARTSYS) fscache_stat(&fscache_n_allocs_intr); else if (ret < 0) fscache_stat(&fscache_n_allocs_nobufs); else fscache_stat(&fscache_n_allocs_ok); fscache_put_retrieval(op); _leave(" = %d", ret); return ret; nobufs_unlock: spin_unlock(&cookie->lock); atomic_dec(&cookie->n_active); kfree(op); nobufs: fscache_stat(&fscache_n_allocs_nobufs); _leave(" = -ENOBUFS"); return -ENOBUFS; } EXPORT_SYMBOL(__fscache_alloc_page); /* * Unmark pages allocate in the readahead code path (via: * fscache_readpages_or_alloc) after delegating to the base filesystem */ void __fscache_readpages_cancel(struct fscache_cookie *cookie, struct list_head *pages) { struct page *page; list_for_each_entry(page, pages, lru) { if (PageFsCache(page)) __fscache_uncache_page(cookie, page); } } EXPORT_SYMBOL(__fscache_readpages_cancel); /* * release a write op reference */ static void fscache_release_write_op(struct fscache_operation *_op) { _enter("{OP%x}", _op->debug_id); } /* * perform the background storage of a page into the cache */ static void fscache_write_op(struct fscache_operation *_op) { struct fscache_storage *op = container_of(_op, struct fscache_storage, op); struct fscache_object *object = op->op.object; struct fscache_cookie *cookie; struct page *page; unsigned n; void *results[1]; int ret; _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage)); spin_lock(&object->lock); cookie = object->cookie; if (!fscache_object_is_active(object)) { /* If we get here, then the on-disk cache object likely longer * exists, so we should just cancel this write operation. */ spin_unlock(&object->lock); fscache_op_complete(&op->op, false); _leave(" [inactive]"); return; } if (!cookie) { /* If we get here, then the cookie belonging to the object was * detached, probably by the cookie being withdrawn due to * memory pressure, which means that the pages we might write * to the cache from no longer exist - therefore, we can just * cancel this write operation. */ spin_unlock(&object->lock); fscache_op_complete(&op->op, false); _leave(" [cancel] op{f=%lx s=%u} obj{s=%s f=%lx}", _op->flags, _op->state, object->state->short_name, object->flags); return; } spin_lock(&cookie->stores_lock); fscache_stat(&fscache_n_store_calls); /* find a page to store */ page = NULL; n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1, FSCACHE_COOKIE_PENDING_TAG); if (n != 1) goto superseded; page = results[0]; _debug("gang %d [%lx]", n, page->index); if (page->index > op->store_limit) { fscache_stat(&fscache_n_store_pages_over_limit); goto superseded; } radix_tree_tag_set(&cookie->stores, page->index, FSCACHE_COOKIE_STORING_TAG); radix_tree_tag_clear(&cookie->stores, page->index, FSCACHE_COOKIE_PENDING_TAG); spin_unlock(&cookie->stores_lock); spin_unlock(&object->lock); fscache_stat(&fscache_n_store_pages); fscache_stat(&fscache_n_cop_write_page); ret = object->cache->ops->write_page(op, page); fscache_stat_d(&fscache_n_cop_write_page); fscache_end_page_write(object, page); if (ret < 0) { fscache_abort_object(object); fscache_op_complete(&op->op, true); } else { fscache_enqueue_operation(&op->op); } _leave(""); return; superseded: /* this writer is going away and there aren't any more things to * write */ _debug("cease"); spin_unlock(&cookie->stores_lock); clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); spin_unlock(&object->lock); fscache_op_complete(&op->op, true); _leave(""); } /* * Clear the pages pending writing for invalidation */ void fscache_invalidate_writes(struct fscache_cookie *cookie) { struct page *page; void *results[16]; int n, i; _enter(""); for (;;) { spin_lock(&cookie->stores_lock); n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, ARRAY_SIZE(results), FSCACHE_COOKIE_PENDING_TAG); if (n == 0) { spin_unlock(&cookie->stores_lock); break; } for (i = n - 1; i >= 0; i--) { page = results[i]; radix_tree_delete(&cookie->stores, page->index); } spin_unlock(&cookie->stores_lock); for (i = n - 1; i >= 0; i--) page_cache_release(results[i]); } _leave(""); } /* * request a page be stored in the cache * - returns: * -ENOMEM - out of memory, nothing done * -ENOBUFS - no backing object available in which to cache the page * 0 - dispatched a write - it'll call end_io_func() when finished * * if the cookie still has a backing object at this point, that object can be * in one of a few states with respect to storage processing: * * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is * set) * * (a) no writes yet * * (b) writes deferred till post-creation (mark page for writing and * return immediately) * * (2) negative lookup, object created, initial fill being made from netfs * * (a) fill point not yet reached this page (mark page for writing and * return) * * (b) fill point passed this page (queue op to store this page) * * (3) object extant (queue op to store this page) * * any other state is invalid */ int __fscache_write_page(struct fscache_cookie *cookie, struct page *page, gfp_t gfp) { struct fscache_storage *op; struct fscache_object *object; int ret; _enter("%p,%x,", cookie, (u32) page->flags); ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); ASSERT(PageFsCache(page)); fscache_stat(&fscache_n_stores); if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { _leave(" = -ENOBUFS [invalidating]"); return -ENOBUFS; } op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY); if (!op) goto nomem; fscache_operation_init(&op->op, fscache_write_op, fscache_release_write_op); op->op.flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_WAITING) | (1 << FSCACHE_OP_UNUSE_COOKIE); ret = radix_tree_maybe_preload(gfp & ~__GFP_HIGHMEM); if (ret < 0) goto nomem_free; ret = -ENOBUFS; spin_lock(&cookie->lock); if (hlist_empty(&cookie->backing_objects)) goto nobufs; object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); if (test_bit(FSCACHE_IOERROR, &object->cache->flags)) goto nobufs; /* add the page to the pending-storage radix tree on the backing * object */ spin_lock(&object->lock); spin_lock(&cookie->stores_lock); _debug("store limit %llx", (unsigned long long) object->store_limit); ret = radix_tree_insert(&cookie->stores, page->index, page); if (ret < 0) { if (ret == -EEXIST) goto already_queued; _debug("insert failed %d", ret); goto nobufs_unlock_obj; } radix_tree_tag_set(&cookie->stores, page->index, FSCACHE_COOKIE_PENDING_TAG); page_cache_get(page); /* we only want one writer at a time, but we do need to queue new * writers after exclusive ops */ if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags)) goto already_pending; spin_unlock(&cookie->stores_lock); spin_unlock(&object->lock); op->op.debug_id = atomic_inc_return(&fscache_op_debug_id); op->store_limit = object->store_limit; atomic_inc(&cookie->n_active); if (fscache_submit_op(object, &op->op) < 0) goto submit_failed; spin_unlock(&cookie->lock); radix_tree_preload_end(); fscache_stat(&fscache_n_store_ops); fscache_stat(&fscache_n_stores_ok); /* the work queue now carries its own ref on the object */ fscache_put_operation(&op->op); _leave(" = 0"); return 0; already_queued: fscache_stat(&fscache_n_stores_again); already_pending: spin_unlock(&cookie->stores_lock); spin_unlock(&object->lock); spin_unlock(&cookie->lock); radix_tree_preload_end(); kfree(op); fscache_stat(&fscache_n_stores_ok); _leave(" = 0"); return 0; submit_failed: atomic_dec(&cookie->n_active); spin_lock(&cookie->stores_lock); radix_tree_delete(&cookie->stores, page->index); spin_unlock(&cookie->stores_lock); page_cache_release(page); ret = -ENOBUFS; goto nobufs; nobufs_unlock_obj: spin_unlock(&cookie->stores_lock); spin_unlock(&object->lock); nobufs: spin_unlock(&cookie->lock); radix_tree_preload_end(); kfree(op); fscache_stat(&fscache_n_stores_nobufs); _leave(" = -ENOBUFS"); return -ENOBUFS; nomem_free: kfree(op); nomem: fscache_stat(&fscache_n_stores_oom); _leave(" = -ENOMEM"); return -ENOMEM; } EXPORT_SYMBOL(__fscache_write_page); /* * remove a page from the cache */ void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page) { struct fscache_object *object; _enter(",%p", page); ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); ASSERTCMP(page, !=, NULL); fscache_stat(&fscache_n_uncaches); /* cache withdrawal may beat us to it */ if (!PageFsCache(page)) goto done; /* get the object */ spin_lock(&cookie->lock); if (hlist_empty(&cookie->backing_objects)) { ClearPageFsCache(page); goto done_unlock; } object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); /* there might now be stuff on disk we could read */ clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); /* only invoke the cache backend if we managed to mark the page * uncached here; this deals with synchronisation vs withdrawal */ if (TestClearPageFsCache(page) && object->cache->ops->uncache_page) { /* the cache backend releases the cookie lock */ fscache_stat(&fscache_n_cop_uncache_page); object->cache->ops->uncache_page(object, page); fscache_stat_d(&fscache_n_cop_uncache_page); goto done; } done_unlock: spin_unlock(&cookie->lock); done: _leave(""); } EXPORT_SYMBOL(__fscache_uncache_page); /** * fscache_mark_page_cached - Mark a page as being cached * @op: The retrieval op pages are being marked for * @page: The page to be marked * * Mark a netfs page as being cached. After this is called, the netfs * must call fscache_uncache_page() to remove the mark. */ void fscache_mark_page_cached(struct fscache_retrieval *op, struct page *page) { struct fscache_cookie *cookie = op->op.object->cookie; #ifdef CONFIG_FSCACHE_STATS atomic_inc(&fscache_n_marks); #endif _debug("- mark %p{%lx}", page, page->index); if (TestSetPageFsCache(page)) { static bool once_only; if (!once_only) { once_only = true; printk(KERN_WARNING "FS-Cache:" " Cookie type %s marked page %lx" " multiple times\n", cookie->def->name, page->index); } } if (cookie->def->mark_page_cached) cookie->def->mark_page_cached(cookie->netfs_data, op->mapping, page); } EXPORT_SYMBOL(fscache_mark_page_cached); /** * fscache_mark_pages_cached - Mark pages as being cached * @op: The retrieval op pages are being marked for * @pagevec: The pages to be marked * * Mark a bunch of netfs pages as being cached. After this is called, * the netfs must call fscache_uncache_page() to remove the mark. */ void fscache_mark_pages_cached(struct fscache_retrieval *op, struct pagevec *pagevec) { unsigned long loop; for (loop = 0; loop < pagevec->nr; loop++) fscache_mark_page_cached(op, pagevec->pages[loop]); pagevec_reinit(pagevec); } EXPORT_SYMBOL(fscache_mark_pages_cached); /* * Uncache all the pages in an inode that are marked PG_fscache, assuming them * to be associated with the given cookie. */ void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie, struct inode *inode) { struct address_space *mapping = inode->i_mapping; struct pagevec pvec; pgoff_t next; int i; _enter("%p,%p", cookie, inode); if (!mapping || mapping->nrpages == 0) { _leave(" [no pages]"); return; } pagevec_init(&pvec, 0); next = 0; do { if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) break; for (i = 0; i < pagevec_count(&pvec); i++) { struct page *page = pvec.pages[i]; next = page->index; if (PageFsCache(page)) { __fscache_wait_on_page_write(cookie, page); __fscache_uncache_page(cookie, page); } } pagevec_release(&pvec); cond_resched(); } while (++next); _leave(""); } EXPORT_SYMBOL(__fscache_uncache_all_inode_pages);