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| author | Vladimir Davydov <vdavydov@parallels.com> | 2015-04-14 15:46:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-14 16:49:03 -0700 |
| commit | 3cb29d11174f29b76addcba4374884b14f8ea4b1 (patch) | |
| tree | d73223beced01147ddeebf3a78ccc6ab4f8ffe15 /include | |
| parent | 53d85c98566535d7bc69470f008d7dcb09a0fec9 (diff) | |
| download | linux-3cb29d11174f29b76addcba4374884b14f8ea4b1.tar.bz2 | |
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 <vdavydov@parallels.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Bob Liu <lliubbo@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cleancache.h | 4 |
1 files changed, 4 insertions, 0 deletions
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 <linux/exportfs.h> #include <linux/mm.h> +#define CLEANCACHE_NO_POOL -1 +#define CLEANCACHE_NO_BACKEND -2 +#define CLEANCACHE_NO_BACKEND_SHARED -3 + #define CLEANCACHE_KEY_MAX 6 /* |