litmus-rt.git - The LITMUS^RT kernel.

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Commits per author per week (path 'arch/arm/mach-realview/include/mach/debug-macro.S')

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/* FS-Cache cache handling * * Copyright (C) 2007 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 CACHE #include <linux/module.h> #include <linux/slab.h> #include "internal.h" LIST_HEAD(fscache_cache_list); DECLARE_RWSEM(fscache_addremove_sem); DECLARE_WAIT_QUEUE_HEAD(fscache_cache_cleared_wq); EXPORT_SYMBOL(fscache_cache_cleared_wq); static LIST_HEAD(fscache_cache_tag_list); /* * look up a cache tag */ struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *name) { struct fscache_cache_tag *tag, *xtag; /* firstly check for the existence of the tag under read lock */ down_read(&fscache_addremove_sem); list_for_each_entry(tag, &fscache_cache_tag_list, link) { if (strcmp(tag->name, name) == 0) { atomic_inc(&tag->usage); up_read(&fscache_addremove_sem); return tag; } } up_read(&fscache_addremove_sem); /* the tag does not exist - create a candidate */ xtag = kzalloc(sizeof(*xtag) + strlen(name) + 1, GFP_KERNEL); if (!xtag) /* return a dummy tag if out of memory */ return ERR_PTR(-ENOMEM); atomic_set(&xtag->usage, 1); strcpy(xtag->name, name); /* write lock, search again and add if still not present */ down_write(&fscache_addremove_sem); list_for_each_entry(tag, &fscache_cache_tag_list, link) { if (strcmp(tag->name, name) == 0) { atomic_inc(&tag->usage); up_write(&fscache_addremove_sem); kfree(xtag); return tag; } } list_add_tail(&xtag->link, &fscache_cache_tag_list); up_write(&fscache_addremove_sem); return xtag; } /* * release a reference to a cache tag */ void __fscache_release_cache_tag(struct fscache_cache_tag *tag) { if (tag != ERR_PTR(-ENOMEM)) { down_write(&fscache_addremove_sem); if (atomic_dec_and_test(&tag->usage)) list_del_init(&tag->link); else tag = NULL; up_write(&fscache_addremove_sem); kfree(tag); } } /* * select a cache in which to store an object * - the cache addremove semaphore must be at least read-locked by the caller * - the object will never be an index */ struct fscache_cache *fscache_select_cache_for_object( struct fscache_cookie *cookie) { struct fscache_cache_tag *tag; struct fscache_object *object; struct fscache_cache *cache; _enter(""); if (list_empty(&fscache_cache_list)) { _leave(" = NULL [no cache]"); return NULL; } /* we check the parent to determine the cache to use */ spin_lock(&cookie->lock); /* the first in the parent's backing list should be the preferred * cache */ if (!hlist_empty(&cookie->backing_objects)) { object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); cache = object->cache; if (object->state >= FSCACHE_OBJECT_DYING || test_bit(FSCACHE_IOERROR, &cache->flags)) cache = NULL; spin_unlock(&cookie->lock); _leave(" = %p [parent]", cache); return cache; } /* the parent is unbacked */ if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) { /* cookie not an index and is unbacked */ spin_unlock(&cookie->lock); _leave(" = NULL [cookie ub,ni]"); return NULL; } spin_unlock(&cookie->lock); if (!cookie->def->select_cache) goto no_preference; /* ask the netfs for its preference */ tag = cookie->def->select_cache(cookie->parent->netfs_data, cookie->netfs_data); if (!tag) goto no_preference; if (tag == ERR_PTR(-ENOMEM)) { _leave(" = NULL [nomem tag]"); return NULL; } if (!tag->cache) { _leave(" = NULL [unbacked tag]"); return NULL; } if (test_bit(FSCACHE_IOERROR, &tag->cache->flags)) return NULL; _leave(" = %p [specific]", tag->cache); return tag->cache; no_preference: /* netfs has no preference - just select first cache */ cache = list_entry(fscache_cache_list.next, struct fscache_cache, link); _leave(" = %p [first]", cache); return cache; } /** * fscache_init_cache - Initialise a cache record * @cache: The cache record to be initialised * @ops: The cache operations to be installed in that record * @idfmt: Format string to define identifier * @...: sprintf-style arguments * * Initialise a record of a cache and fill in the name. * * See Documentation/filesystems/caching/backend-api.txt for a complete * description. */ void fscache_init_cache(struct fscache_cache *cache, const struct fscache_cache_ops *ops, const char *idfmt, ...) { va_list va; memset(cache, 0, sizeof(*cache)); cache->ops = ops; va_start(va, idfmt); vsnprintf(cache->identifier, sizeof(cache->identifier), idfmt, va); va_end(va); INIT_WORK(&cache->op_gc, fscache_operation_gc); INIT_LIST_HEAD(&cache->link); INIT_LIST_HEAD(&cache->object_list); INIT_LIST_HEAD(&cache->op_gc_list); spin_lock_init(&cache->object_list_lock); spin_lock_init(&cache->op_gc_list_lock); } EXPORT_SYMBOL(fscache_init_cache); /** * fscache_add_cache - Declare a cache as being open for business * @cache: The record describing the cache * @ifsdef: The record of the cache object describing the top-level index * @tagname: The tag describing this cache * * Add a cache to the system, making it available for netfs's to use. * * See Documentation/filesystems/caching/backend-api.txt for a complete * description. */ int fscache_add_cache(struct fscache_cache *cache, struct fscache_object *ifsdef, const char *tagname) { struct fscache_cache_tag *tag; BUG_ON(!cache->ops); BUG_ON(!ifsdef);


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