Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752336AbbBVScX (ORCPT ); Sun, 22 Feb 2015 13:32:23 -0500 Received: from mx2.parallels.com ([199.115.105.18]:46194 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752284AbbBVScU (ORCPT ); Sun, 22 Feb 2015 13:32:20 -0500 From: Vladimir Davydov To: Andrew Morton CC: Konrad Rzeszutek Wilk , Boris Ostrovsky , David Vrabel , Mark Fasheh , Joel Becker , Stefan Hengelein , Florian Schmaus , Andor Daam , Dan Magenheimer , Bob Liu , , Subject: [PATCH 4/4] cleancache: remove limit on the number of cleancache enabled filesystems Date: Sun, 22 Feb 2015 21:31:55 +0300 Message-ID: <59565910773bb5f9ba380b8ceb9de9a6c68180f1.1424628280.git.vdavydov@parallels.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [81.5.99.36] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 15701 Lines: 468 The limit equals 32 and is imposed by the number of entries in the fs_poolid_map and shared_fs_poolid_map. Nowadays it is insufficient, because with containers on board a Linux host can have hundreds of active fs mounts. These maps were introduced by commit 49a9ab815acb8 ("mm: cleancache: lazy initialization to allow tmem backends to build/run as modules") in order to allow compiling cleancache drivers as modules. Real pool ids are stored in these maps while super_block->cleancache_poolid points to an entry in the map, so that on cleancache registration we can walk over all (if there are <= 32 of them, of course) cleancache-enabled super blocks and assign real pool ids. Actually, there is absolutely no need in these maps, because we can iterate over all super blocks immediately using iterate_supers. This is not racy, because cleancache_init_ops is called from mount_fs with super_block->s_umount held for writing, while iterate_supers takes this semaphore for reading, so if we call iterate_supers after setting cleancache_ops, all super blocks that had been created before cleancache_register_ops was called will be assigned pool ids by the action function of iterate_supers while all newer super blocks will receive it in cleancache_init_fs. This patch therefore removes the maps and hence the artificial limit on the number of cleancache enabled filesystems. Signed-off-by: Vladimir Davydov --- fs/super.c | 2 +- include/linux/cleancache.h | 4 + mm/cleancache.c | 260 +++++++++++--------------------------------- 3 files changed, 71 insertions(+), 195 deletions(-) diff --git a/fs/super.c b/fs/super.c index 65a53efc1cf4..ed5a9b9c3206 100644 --- a/fs/super.c +++ b/fs/super.c @@ -224,7 +224,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags) s->s_maxbytes = MAX_NON_LFS; s->s_op = &default_op; s->s_time_gran = 1000000000; - s->cleancache_poolid = -1; + s->cleancache_poolid = CLEANCACHE_NO_POOL; s->s_shrink.seeks = DEFAULT_SEEKS; s->s_shrink.scan_objects = super_cache_scan; diff --git a/include/linux/cleancache.h b/include/linux/cleancache.h index b23611f43cfb..bda5ec0b4b4d 100644 --- a/include/linux/cleancache.h +++ b/include/linux/cleancache.h @@ -5,6 +5,10 @@ #include #include +#define CLEANCACHE_NO_POOL -1 +#define CLEANCACHE_NO_BACKEND -2 +#define CLEANCACHE_NO_BACKEND_SHARED -3 + #define CLEANCACHE_KEY_MAX 6 /* diff --git a/mm/cleancache.c b/mm/cleancache.c index aa10f9a3bc88..5e357a3cd897 100644 --- a/mm/cleancache.c +++ b/mm/cleancache.c @@ -12,6 +12,7 @@ */ #include +#include #include #include #include @@ -19,10 +20,11 @@ #include /* - * cleancache_ops is set by cleancache_ops_register to contain the pointers + * cleancache_ops is set by cleancache_register_ops to contain the pointers * to the cleancache "backend" implementation functions. */ static struct cleancache_ops *cleancache_ops __read_mostly; +static DEFINE_SPINLOCK(cleancache_ops_lock); /* * Counters available via /sys/kernel/debug/cleancache (if debugfs is @@ -34,104 +36,32 @@ static u64 cleancache_failed_gets; static u64 cleancache_puts; static u64 cleancache_invalidates; -/* - * When no backend is registered all calls to init_fs and init_shared_fs - * are registered and fake poolids (FAKE_FS_POOLID_OFFSET or - * FAKE_SHARED_FS_POOLID_OFFSET, plus offset in the respective array - * [shared_|]fs_poolid_map) are given to the respective super block - * (sb->cleancache_poolid) and no tmem_pools are created. When a backend - * registers with cleancache the previous calls to init_fs and init_shared_fs - * are executed to create tmem_pools and set the respective poolids. While no - * backend is registered all "puts", "gets" and "flushes" are ignored or failed. - */ -#define MAX_INITIALIZABLE_FS 32 -#define FAKE_FS_POOLID_OFFSET 1000 -#define FAKE_SHARED_FS_POOLID_OFFSET 2000 - -#define FS_NO_BACKEND (-1) -#define FS_UNKNOWN (-2) -static int fs_poolid_map[MAX_INITIALIZABLE_FS]; -static int shared_fs_poolid_map[MAX_INITIALIZABLE_FS]; -static char *uuids[MAX_INITIALIZABLE_FS]; -/* - * Mutex for the [shared_|]fs_poolid_map to guard against multiple threads - * invoking umount (and ending in __cleancache_invalidate_fs) and also multiple - * threads calling mount (and ending up in __cleancache_init_[shared|]fs). - */ -static DEFINE_MUTEX(poolid_mutex); -/* - * When set to false (default) all calls to the cleancache functions, except - * the __cleancache_invalidate_fs and __cleancache_init_[shared|]fs are guarded - * by the if (!cleancache_ops) return. This means multiple threads (from - * different filesystems) will be checking cleancache_ops. The usage of a - * bool instead of a atomic_t or a bool guarded by a spinlock is OK - we are - * OK if the time between the backend's have been initialized (and - * cleancache_ops has been set to not NULL) and when the filesystems start - * actually calling the backends. The inverse (when unloading) is obviously - * not good - but this shim does not do that (yet). - */ - -/* - * The backends and filesystems work all asynchronously. This is b/c the - * backends can be built as modules. - * The usual sequence of events is: - * a) mount / -> __cleancache_init_fs is called. We set the - * [shared_|]fs_poolid_map and uuids for. - * - * b). user does I/Os -> we call the rest of __cleancache_* functions - * which return immediately as cleancache_ops is false. - * - * c). modprobe zcache -> cleancache_register_ops. We init the backend - * and set cleancache_ops to true, and for any fs_poolid_map - * (which is set by __cleancache_init_fs) we initialize the poolid. - * - * d). user does I/Os -> now that cleancache_ops is true all the - * __cleancache_* functions can call the backend. They all check - * that fs_poolid_map is valid and if so invoke the backend. - * - * e). umount / -> __cleancache_invalidate_fs, the fs_poolid_map is - * reset (which is the second check in the __cleancache_* ops - * to call the backend). - * - * The sequence of event could also be c), followed by a), and d). and e). The - * c) would not happen anymore. There is also the chance of c), and one thread - * doing a) + d), and another doing e). For that case we depend on the - * filesystem calling __cleancache_invalidate_fs in the proper sequence (so - * that it handles all I/Os before it invalidates the fs (which is last part - * of unmounting process). - * - * Note: The acute reader will notice that there is no "rmmod zcache" case. - * This is b/c the functionality for that is not yet implemented and when - * done, will require some extra locking not yet devised. - */ +static void cleancache_register_ops_sb(struct super_block *sb, void *unused) +{ + switch (sb->cleancache_poolid) { + case CLEANCACHE_NO_BACKEND: + __cleancache_init_fs(sb); + break; + case CLEANCACHE_NO_BACKEND_SHARED: + __cleancache_init_shared_fs(sb); + break; + } +} /* * Register operations for cleancache. Returns 0 on success. */ int cleancache_register_ops(struct cleancache_ops *ops) { - int i; - - mutex_lock(&poolid_mutex); + spin_lock(&cleancache_ops_lock); if (cleancache_ops) { - mutex_unlock(&poolid_mutex); + spin_unlock(&cleancache_ops_lock); return -EBUSY; } - for (i = 0; i < MAX_INITIALIZABLE_FS; i++) { - if (fs_poolid_map[i] == FS_NO_BACKEND) - fs_poolid_map[i] = ops->init_fs(PAGE_SIZE); - if (shared_fs_poolid_map[i] == FS_NO_BACKEND) - shared_fs_poolid_map[i] = ops->init_shared_fs - (uuids[i], PAGE_SIZE); - } - /* - * We MUST set cleancache_ops _after_ we have called the backends - * init_fs or init_shared_fs functions. Otherwise the compiler might - * re-order where cleancache_ops is set in this function. - */ - barrier(); cleancache_ops = ops; - mutex_unlock(&poolid_mutex); + spin_unlock(&cleancache_ops_lock); + + iterate_supers(cleancache_register_ops_sb, NULL); return 0; } EXPORT_SYMBOL(cleancache_register_ops); @@ -139,42 +69,28 @@ EXPORT_SYMBOL(cleancache_register_ops); /* Called by a cleancache-enabled filesystem at time of mount */ void __cleancache_init_fs(struct super_block *sb) { - int i; - - mutex_lock(&poolid_mutex); - for (i = 0; i < MAX_INITIALIZABLE_FS; i++) { - if (fs_poolid_map[i] == FS_UNKNOWN) { - sb->cleancache_poolid = i + FAKE_FS_POOLID_OFFSET; - if (cleancache_ops) - fs_poolid_map[i] = cleancache_ops->init_fs(PAGE_SIZE); - else - fs_poolid_map[i] = FS_NO_BACKEND; - break; - } + int pool_id = CLEANCACHE_NO_BACKEND; + + if (cleancache_ops) { + pool_id = cleancache_ops->init_fs(PAGE_SIZE); + if (pool_id < 0) + pool_id = CLEANCACHE_NO_POOL; } - mutex_unlock(&poolid_mutex); + sb->cleancache_poolid = pool_id; } EXPORT_SYMBOL(__cleancache_init_fs); /* Called by a cleancache-enabled clustered filesystem at time of mount */ void __cleancache_init_shared_fs(struct super_block *sb) { - int i; - - mutex_lock(&poolid_mutex); - for (i = 0; i < MAX_INITIALIZABLE_FS; i++) { - if (shared_fs_poolid_map[i] == FS_UNKNOWN) { - sb->cleancache_poolid = i + FAKE_SHARED_FS_POOLID_OFFSET; - uuids[i] = sb->s_uuid; - if (cleancache_ops) - shared_fs_poolid_map[i] = cleancache_ops->init_shared_fs - (sb->s_uuid, PAGE_SIZE); - else - shared_fs_poolid_map[i] = FS_NO_BACKEND; - break; - } + int pool_id = CLEANCACHE_NO_BACKEND_SHARED; + + if (cleancache_ops) { + pool_id = cleancache_ops->init_shared_fs(sb->s_uuid, PAGE_SIZE); + if (pool_id < 0) + pool_id = CLEANCACHE_NO_POOL; } - mutex_unlock(&poolid_mutex); + sb->cleancache_poolid = pool_id; } EXPORT_SYMBOL(__cleancache_init_shared_fs); @@ -204,19 +120,6 @@ static int cleancache_get_key(struct inode *inode, } /* - * Returns a pool_id that is associated with a given fake poolid. - */ -static int get_poolid_from_fake(int fake_pool_id) -{ - if (fake_pool_id >= FAKE_SHARED_FS_POOLID_OFFSET) - return shared_fs_poolid_map[fake_pool_id - - FAKE_SHARED_FS_POOLID_OFFSET]; - else if (fake_pool_id >= FAKE_FS_POOLID_OFFSET) - return fs_poolid_map[fake_pool_id - FAKE_FS_POOLID_OFFSET]; - return FS_NO_BACKEND; -} - -/* * "Get" data from cleancache associated with the poolid/inode/index * that were specified when the data was put to cleanache and, if * successful, use it to fill the specified page with data and return 0. @@ -231,26 +134,20 @@ int __cleancache_get_page(struct page *page) { int ret = -1; int pool_id; - int fake_pool_id; struct cleancache_filekey key = { .u.key = { 0 } }; - if (!cleancache_ops) { - cleancache_failed_gets++; + if (!cleancache_ops) goto out; - } VM_BUG_ON_PAGE(!PageLocked(page), page); - fake_pool_id = page->mapping->host->i_sb->cleancache_poolid; - if (fake_pool_id < 0) + pool_id = page->mapping->host->i_sb->cleancache_poolid; + if (pool_id < 0) goto out; - pool_id = get_poolid_from_fake(fake_pool_id); if (cleancache_get_key(page->mapping->host, &key) < 0) goto out; - if (pool_id >= 0) - ret = cleancache_ops->get_page(pool_id, - key, page->index, page); + ret = cleancache_ops->get_page(pool_id, key, page->index, page); if (ret == 0) cleancache_succ_gets++; else @@ -273,26 +170,21 @@ EXPORT_SYMBOL(__cleancache_get_page); void __cleancache_put_page(struct page *page) { int pool_id; - int fake_pool_id; struct cleancache_filekey key = { .u.key = { 0 } }; - if (!cleancache_ops) { - cleancache_puts++; + if (!cleancache_ops) return; - } VM_BUG_ON_PAGE(!PageLocked(page), page); - fake_pool_id = page->mapping->host->i_sb->cleancache_poolid; - if (fake_pool_id < 0) + pool_id = page->mapping->host->i_sb->cleancache_poolid; + if (pool_id < 0) return; - pool_id = get_poolid_from_fake(fake_pool_id); + if (cleancache_get_key(page->mapping->host, &key) < 0) + return; - if (pool_id >= 0 && - cleancache_get_key(page->mapping->host, &key) >= 0) { - cleancache_ops->put_page(pool_id, key, page->index, page); - cleancache_puts++; - } + cleancache_ops->put_page(pool_id, key, page->index, page); + cleancache_puts++; } EXPORT_SYMBOL(__cleancache_put_page); @@ -309,24 +201,21 @@ void __cleancache_invalidate_page(struct address_space *mapping, { /* careful... page->mapping is NULL sometimes when this is called */ int pool_id; - int fake_pool_id = mapping->host->i_sb->cleancache_poolid; struct cleancache_filekey key = { .u.key = { 0 } }; if (!cleancache_ops) return; - if (fake_pool_id >= 0) { - pool_id = get_poolid_from_fake(fake_pool_id); - if (pool_id < 0) - return; + VM_BUG_ON_PAGE(!PageLocked(page), page); + pool_id = mapping->host->i_sb->cleancache_poolid; + if (pool_id < 0) + return; - VM_BUG_ON_PAGE(!PageLocked(page), page); - if (cleancache_get_key(mapping->host, &key) >= 0) { - cleancache_ops->invalidate_page(pool_id, - key, page->index); - cleancache_invalidates++; - } - } + if (cleancache_get_key(mapping->host, &key) < 0) + return; + + cleancache_ops->invalidate_page(pool_id, key, page->index); + cleancache_invalidates++; } EXPORT_SYMBOL(__cleancache_invalidate_page); @@ -342,19 +231,19 @@ EXPORT_SYMBOL(__cleancache_invalidate_page); void __cleancache_invalidate_inode(struct address_space *mapping) { int pool_id; - int fake_pool_id = mapping->host->i_sb->cleancache_poolid; struct cleancache_filekey key = { .u.key = { 0 } }; if (!cleancache_ops) return; - if (fake_pool_id < 0) + pool_id = mapping->host->i_sb->cleancache_poolid; + if (pool_id < 0) return; - pool_id = get_poolid_from_fake(fake_pool_id); + if (cleancache_get_key(mapping->host, &key) < 0) + return; - if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0) - cleancache_ops->invalidate_inode(pool_id, key); + cleancache_ops->invalidate_inode(pool_id, key); } EXPORT_SYMBOL(__cleancache_invalidate_inode); @@ -365,32 +254,19 @@ EXPORT_SYMBOL(__cleancache_invalidate_inode); */ void __cleancache_invalidate_fs(struct super_block *sb) { - int index; - int fake_pool_id = sb->cleancache_poolid; - int old_poolid = fake_pool_id; - - mutex_lock(&poolid_mutex); - if (fake_pool_id >= FAKE_SHARED_FS_POOLID_OFFSET) { - index = fake_pool_id - FAKE_SHARED_FS_POOLID_OFFSET; - old_poolid = shared_fs_poolid_map[index]; - shared_fs_poolid_map[index] = FS_UNKNOWN; - uuids[index] = NULL; - } else if (fake_pool_id >= FAKE_FS_POOLID_OFFSET) { - index = fake_pool_id - FAKE_FS_POOLID_OFFSET; - old_poolid = fs_poolid_map[index]; - fs_poolid_map[index] = FS_UNKNOWN; - } - sb->cleancache_poolid = -1; - if (cleancache_ops) - cleancache_ops->invalidate_fs(old_poolid); - mutex_unlock(&poolid_mutex); + int pool_id; + + pool_id = sb->cleancache_poolid; + if (pool_id < 0) + return; + + sb->cleancache_poolid = CLEANCACHE_NO_POOL; + cleancache_ops->invalidate_fs(pool_id); } EXPORT_SYMBOL(__cleancache_invalidate_fs); static int __init init_cleancache(void) { - int i; - #ifdef CONFIG_DEBUG_FS struct dentry *root = debugfs_create_dir("cleancache", NULL); if (root == NULL) @@ -402,10 +278,6 @@ static int __init init_cleancache(void) debugfs_create_u64("invalidates", S_IRUGO, root, &cleancache_invalidates); #endif - for (i = 0; i < MAX_INITIALIZABLE_FS; i++) { - fs_poolid_map[i] = FS_UNKNOWN; - shared_fs_poolid_map[i] = FS_UNKNOWN; - } return 0; } module_init(init_cleancache) -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/