Messages in this thread Patch in this message | | | Date | Tue, 09 Dec 2008 23:48:45 +0100 | From | Eric Dumazet <> | Subject | [PATCH] fs: filp_cachep can be static in fs/file_table.c |
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Hi Andrew
Please find two cleanups before patch re-submission to use SLAB_DESTROY_BY_RCU for "struct file".
Thank you
[PATCH] fs: filp_cachep can be static in fs/file_table.c
1) Documentation cleanup
Documentation/filesystems/files.txt was not updated when f_count became an atomic_long_t. atomic_long_inc_not_zero() is now used instead of atomic_inc_not_zero()
2) filp_cachep can be static to fs/file_table.c
Instead of creating the "filp" kmem_cache in vfs_caches_init(), we can do it a litle be later in files_init(), so that filp_cachep is static to fs/file_table.c
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> --- Documentation/filesystems/files.txt | 6 +++--- fs/dcache.c | 6 ------ fs/file_table.c | 10 +++++++++- include/linux/fdtable.h | 2 -- 4 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/Documentation/filesystems/files.txt b/Documentation/filesystems/files.txt index bb0142f..ac2facc 100644 --- a/Documentation/filesystems/files.txt +++ b/Documentation/filesystems/files.txt @@ -76,13 +76,13 @@ the fdtable structure - 5. Handling of the file structures is special. Since the look-up of the fd (fget()/fget_light()) are lock-free, it is possible that look-up may race with the last put() operation on the - file structure. This is avoided using atomic_inc_not_zero() + file structure. This is avoided using atomic_long_inc_not_zero() on ->f_count : rcu_read_lock(); file = fcheck_files(files, fd); if (file) { - if (atomic_inc_not_zero(&file->f_count)) + if (atomic_long_inc_not_zero(&file->f_count)) *fput_needed = 1; else /* Didn't get the reference, someone's freed */ @@ -92,7 +92,7 @@ the fdtable structure - .... return file; - atomic_inc_not_zero() detects if refcounts is already zero or + atomic_long_inc_not_zero() detects if refcounts is already zero or goes to zero during increment. If it does, we fail fget()/fget_light(). diff --git a/fs/dcache.c b/fs/dcache.c index a1d86c7..fa1ba03 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2313,9 +2313,6 @@ static void __init dcache_init(void) /* SLAB cache for __getname() consumers */ struct kmem_cache *names_cachep __read_mostly; -/* SLAB cache for file structures */ -struct kmem_cache *filp_cachep __read_mostly; - EXPORT_SYMBOL(d_genocide); void __init vfs_caches_init_early(void) @@ -2337,9 +2334,6 @@ void __init vfs_caches_init(unsigned long mempages) names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); - filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, - SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); - dcache_init(); inode_init(); files_init(mempages); diff --git a/fs/file_table.c b/fs/file_table.c index 5ad0eca..a46e880 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -32,6 +32,9 @@ struct files_stat_struct files_stat = { /* public. Not pretty! */ __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); +/* SLAB cache for file structures */ +static struct kmem_cache *filp_cachep __read_mostly; + static struct percpu_counter nr_files __cacheline_aligned_in_smp; static inline void file_free_rcu(struct rcu_head *head) @@ -397,7 +400,12 @@ too_bad: void __init files_init(unsigned long mempages) { int n; - /* One file with associated inode and dcache is very roughly 1K. + + filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, + SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); + + /* + * One file with associated inode and dcache is very roughly 1K. * Per default don't use more than 10% of our memory for files. */ diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index 4aab6f1..09d6c5b 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -57,8 +57,6 @@ struct files_struct { #define files_fdtable(files) (rcu_dereference((files)->fdt)) -extern struct kmem_cache *filp_cachep; - struct file_operations; struct vfsmount; struct dentry;
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