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Subject[PATCH] Use slab in pipe code
Hi Linus,

this patch makes the pipe code use the slab allocator instead of
kmalloc/kfree. The changes are pretty small, so I think it's ok
for the stable series.

Christoph

--
Of course it doesn't work. We've performed a software upgrade.


--- linux-2.4.2-pre3/fs/pipe.c Sat Feb 10 20:03:33 2001
+++ linux/fs/pipe.c Sat Feb 10 20:36:57 2001
@@ -21,8 +21,13 @@
*
* Reads with count = 0 should always return 0.
* -- Julian Bradfield 1999-06-07.
+ *
+ * Use slab allocator instead of kmalloc/kfree.
+ * -- Christoph Hellwig 2001-02-07
*/

+static kmem_cache_t * pipe_cachep;
+
/* Drop the inode semaphore and wait for a pipe event, atomically */
void pipe_wait(struct inode * inode)
{
@@ -448,7 +453,7 @@
if (!page)
return NULL;

- inode->i_pipe = kmalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
+ inode->i_pipe = kmem_cache_alloc(pipe_cachep, SLAB_KERNEL);
if (!inode->i_pipe)
goto fail_page;

@@ -578,7 +583,7 @@
put_unused_fd(i);
close_f12_inode:
free_page((unsigned long) PIPE_BASE(*inode));
- kfree(inode->i_pipe);
+ kmem_cache_free(pipe_cachep, inode->i_pipe);
inode->i_pipe = NULL;
iput(inode);
close_f12:
@@ -635,15 +640,28 @@

static int __init init_pipe_fs(void)
{
- int err = register_filesystem(&pipe_fs_type);
- if (!err) {
- pipe_mnt = kern_mount(&pipe_fs_type);
- err = PTR_ERR(pipe_mnt);
- if (IS_ERR(pipe_mnt))
- unregister_filesystem(&pipe_fs_type);
- else
- err = 0;
- }
+ int err = -ENOMEM;
+
+ pipe_cachep = kmem_cache_create("pipe_cache",
+ sizeof(struct pipe_inode_info), 0,
+ SLAB_HWCACHE_ALIGN, NULL, NULL);
+ if (pipe_cachep == NULL)
+ goto err_out;
+
+ err = register_filesystem(&pipe_fs_type);
+ if (err)
+ goto err_out;
+
+ pipe_mnt = kern_mount(&pipe_fs_type);
+
+ err = PTR_ERR(pipe_mnt);
+ if (!IS_ERR(pipe_mnt))
+ return 0;
+
+ unregister_filesystem(&pipe_fs_type);
+
+err_out:
+ kmem_cache_destroy(pipe_cachep);
return err;
}

@@ -651,6 +669,7 @@
{
unregister_filesystem(&pipe_fs_type);
kern_umount(pipe_mnt);
+ kmem_cache_destroy(pipe_cachep);
}

module_init(init_pipe_fs)
-
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