From ee1462458cb543bbcfd379176bbba0d4bd052b7f Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Wed, 15 Apr 2015 16:14:11 -0700 Subject: [PATCH] fs, jfs: remove slab object constructor Mempools based on slab caches with object constructors are risky because element allocation can happen either from the slab cache itself, meaning the constructor is properly called before returning, or from the mempool reserve pool, meaning the constructor is not called before returning, depending on the allocation context. For this reason, we should disallow creating mempools based on slab caches that have object constructors. Callers of mempool_alloc() will be responsible for properly initializing the returned element. Then, it doesn't matter if the element came from the slab cache or the mempool reserved pool. The only occurrence of a mempool being based on a slab cache with an object constructor in the tree is in fs/jfs/jfs_metapage.c. Remove it and properly initialize the element in alloc_metapage(). At the same time, META_free is never used, so remove it as well. Signed-off-by: David Rientjes Acked-by: Dave Kleikamp Cc: Christoph Hellwig Cc: Sebastian Ott Cc: Mikulas Patocka Cc: Catalin Marinas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/jfs/jfs_metapage.c | 31 ++++++++++++------------------- fs/jfs/jfs_metapage.h | 1 - 2 files changed, 12 insertions(+), 20 deletions(-) diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c index 49ba7ff1bbb9..16a0922beb59 100644 --- a/fs/jfs/jfs_metapage.c +++ b/fs/jfs/jfs_metapage.c @@ -183,30 +183,23 @@ static inline void remove_metapage(struct page *page, struct metapage *mp) #endif -static void init_once(void *foo) -{ - struct metapage *mp = (struct metapage *)foo; - - mp->lid = 0; - mp->lsn = 0; - mp->flag = 0; - mp->data = NULL; - mp->clsn = 0; - mp->log = NULL; - set_bit(META_free, &mp->flag); - init_waitqueue_head(&mp->wait); -} - static inline struct metapage *alloc_metapage(gfp_t gfp_mask) { - return mempool_alloc(metapage_mempool, gfp_mask); + struct metapage *mp = mempool_alloc(metapage_mempool, gfp_mask); + + if (mp) { + mp->lid = 0; + mp->lsn = 0; + mp->data = NULL; + mp->clsn = 0; + mp->log = NULL; + init_waitqueue_head(&mp->wait); + } + return mp; } static inline void free_metapage(struct metapage *mp) { - mp->flag = 0; - set_bit(META_free, &mp->flag); - mempool_free(mp, metapage_mempool); } @@ -216,7 +209,7 @@ int __init metapage_init(void) * Allocate the metapage structures */ metapage_cache = kmem_cache_create("jfs_mp", sizeof(struct metapage), - 0, 0, init_once); + 0, 0, NULL); if (metapage_cache == NULL) return -ENOMEM; diff --git a/fs/jfs/jfs_metapage.h b/fs/jfs/jfs_metapage.h index a78beda85f68..337e9e51ac06 100644 --- a/fs/jfs/jfs_metapage.h +++ b/fs/jfs/jfs_metapage.h @@ -48,7 +48,6 @@ struct metapage { /* metapage flag */ #define META_locked 0 -#define META_free 1 #define META_dirty 2 #define META_sync 3 #define META_discard 4