From 9de1626290eaa7d921413ddc83544bc3bae27283 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Tue, 14 Apr 2015 15:46:42 -0700 Subject: cleancache: zap uuid arg of cleancache_init_shared_fs Use super_block->s_uuid instead. Every shared filesystem using cleancache must now initialize super_block->s_uuid before calling cleancache_init_shared_fs. The only one on the tree, ocfs2, already meets this requirement. Signed-off-by: Vladimir Davydov Cc: Konrad Rzeszutek Wilk Cc: Boris Ostrovsky Cc: David Vrabel Cc: Mark Fasheh Cc: Joel Becker Cc: Stefan Hengelein Cc: Florian Schmaus Cc: Andor Daam Cc: Dan Magenheimer Cc: Bob Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cleancache.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux/cleancache.h') diff --git a/include/linux/cleancache.h b/include/linux/cleancache.h index 4ce9056..29657d1 100644 --- a/include/linux/cleancache.h +++ b/include/linux/cleancache.h @@ -36,7 +36,7 @@ struct cleancache_ops { extern struct cleancache_ops * cleancache_register_ops(struct cleancache_ops *ops); extern void __cleancache_init_fs(struct super_block *); -extern void __cleancache_init_shared_fs(char *, struct super_block *); +extern void __cleancache_init_shared_fs(struct super_block *); extern int __cleancache_get_page(struct page *); extern void __cleancache_put_page(struct page *); extern void __cleancache_invalidate_page(struct address_space *, struct page *); @@ -78,10 +78,10 @@ static inline void cleancache_init_fs(struct super_block *sb) __cleancache_init_fs(sb); } -static inline void cleancache_init_shared_fs(char *uuid, struct super_block *sb) +static inline void cleancache_init_shared_fs(struct super_block *sb) { if (cleancache_enabled) - __cleancache_init_shared_fs(uuid, sb); + __cleancache_init_shared_fs(sb); } static inline int cleancache_get_page(struct page *page) -- cgit v1.1 From 53d85c98566535d7bc69470f008d7dcb09a0fec9 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Tue, 14 Apr 2015 15:46:45 -0700 Subject: cleancache: forbid overriding cleancache_ops Currently, cleancache_register_ops returns the previous value of cleancache_ops to allow chaining. However, chaining, as it is implemented now, is extremely dangerous due to possible pool id collisions. Suppose, a new cleancache driver is registered after the previous one assigned an id to a super block. If the new driver assigns the same id to another super block, which is perfectly possible, we will have two different filesystems using the same id. No matter if the new driver implements chaining or not, we are likely to get data corruption with such a configuration eventually. This patch therefore disables the ability to override cleancache_ops altogether as potentially dangerous. If there is already cleancache driver registered, all further calls to cleancache_register_ops will return EBUSY. Since no user of cleancache implements chaining, we only need to make minor changes to the code outside the cleancache core. Signed-off-by: Vladimir Davydov Cc: Konrad Rzeszutek Wilk Cc: Boris Ostrovsky Cc: David Vrabel Cc: Mark Fasheh Cc: Joel Becker Cc: Stefan Hengelein Cc: Florian Schmaus Cc: Andor Daam Cc: Dan Magenheimer Cc: Bob Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cleancache.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include/linux/cleancache.h') diff --git a/include/linux/cleancache.h b/include/linux/cleancache.h index 29657d1..b23611f 100644 --- a/include/linux/cleancache.h +++ b/include/linux/cleancache.h @@ -33,8 +33,7 @@ struct cleancache_ops { void (*invalidate_fs)(int); }; -extern struct cleancache_ops * - cleancache_register_ops(struct cleancache_ops *ops); +extern int cleancache_register_ops(struct cleancache_ops *ops); extern void __cleancache_init_fs(struct super_block *); extern void __cleancache_init_shared_fs(struct super_block *); extern int __cleancache_get_page(struct page *); -- cgit v1.1 From 3cb29d11174f29b76addcba4374884b14f8ea4b1 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Tue, 14 Apr 2015 15:46:48 -0700 Subject: cleancache: remove limit on the number of cleancache enabled filesystems 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 Cc: Konrad Rzeszutek Wilk Cc: Boris Ostrovsky Cc: David Vrabel Cc: Mark Fasheh Cc: Joel Becker Cc: Stefan Hengelein Cc: Florian Schmaus Cc: Andor Daam Cc: Dan Magenheimer Cc: Bob Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cleancache.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/cleancache.h') diff --git a/include/linux/cleancache.h b/include/linux/cleancache.h index b23611f..bda5ec0b4 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 /* -- cgit v1.1