ceph: ref counted buffer

struct ceph_buffer is a simple ref-counted buffer.  We transparently
choose between kmalloc for small buffers and vmalloc for large ones.

This is currently used only for allocating memory for xattr data.

Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Sage Weil 2009-10-06 11:31:07 -07:00
parent de57606c23
commit c30dbb9cc7
2 changed files with 89 additions and 0 deletions

34
fs/ceph/buffer.c Normal file
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#include "ceph_debug.h"
#include "buffer.h"
struct ceph_buffer *ceph_buffer_new(gfp_t gfp)
{
struct ceph_buffer *b;
b = kmalloc(sizeof(*b), gfp);
if (!b)
return NULL;
atomic_set(&b->nref, 1);
b->vec.iov_base = NULL;
b->vec.iov_len = 0;
b->alloc_len = 0;
return b;
}
int ceph_buffer_alloc(struct ceph_buffer *b, int len, gfp_t gfp)
{
b->vec.iov_base = kmalloc(len, gfp | __GFP_NOWARN);
if (b->vec.iov_base) {
b->is_vmalloc = false;
} else {
b->vec.iov_base = __vmalloc(len, gfp, PAGE_KERNEL);
b->is_vmalloc = true;
}
if (!b->vec.iov_base)
return -ENOMEM;
b->alloc_len = len;
b->vec.iov_len = len;
return 0;
}

55
fs/ceph/buffer.h Normal file
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#ifndef __FS_CEPH_BUFFER_H
#define __FS_CEPH_BUFFER_H
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/types.h>
#include <linux/uio.h>
/*
* a simple reference counted buffer.
*
* use kmalloc for small sizes (<= one page), vmalloc for larger
* sizes.
*/
struct ceph_buffer {
atomic_t nref;
struct kvec vec;
size_t alloc_len;
bool is_vmalloc;
};
struct ceph_buffer *ceph_buffer_new(gfp_t gfp);
int ceph_buffer_alloc(struct ceph_buffer *b, int len, gfp_t gfp);
static inline struct ceph_buffer *ceph_buffer_get(struct ceph_buffer *b)
{
atomic_inc(&b->nref);
return b;
}
static inline void ceph_buffer_put(struct ceph_buffer *b)
{
if (b && atomic_dec_and_test(&b->nref)) {
if (b->vec.iov_base) {
if (b->is_vmalloc)
vfree(b->vec.iov_base);
else
kfree(b->vec.iov_base);
}
kfree(b);
}
}
static inline struct ceph_buffer *ceph_buffer_new_alloc(int len, gfp_t gfp)
{
struct ceph_buffer *b = ceph_buffer_new(gfp);
if (b && ceph_buffer_alloc(b, len, gfp) < 0) {
ceph_buffer_put(b);
b = NULL;
}
return b;
}
#endif