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Subject[PATCH] fs: filp_cachep can be static in fs/file_table.c
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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