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    Subject[PATCH 04/20] ceph: ref counted buffer
    Date
    struct ceph_buffer is a simple ref-counted buffer.  We transparently
    choose between kmalloc for small buffers and vmalloc for large ones.

    This is used for allocating memory for xattr data, among other things.

    Signed-off-by: Sage Weil <sage@newdream.net>
    ---
    fs/ceph/buffer.h | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 93 insertions(+), 0 deletions(-)
    create mode 100644 fs/ceph/buffer.h

    diff --git a/fs/ceph/buffer.h b/fs/ceph/buffer.h
    new file mode 100644
    index 0000000..b4ccb94
    --- /dev/null
    +++ b/fs/ceph/buffer.h
    @@ -0,0 +1,93 @@
    +#ifndef __FS_CEPH_BUFFER_H
    +#define __FS_CEPH_BUFFER_H
    +
    +#include <linux/mm.h>
    +#include <linux/types.h>
    +#include <linux/vmalloc.h>
    +
    +#include "ceph_debug.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_static, is_vmalloc;
    +};
    +
    +static inline void ceph_buffer_init_static(struct ceph_buffer *b)
    +{
    + atomic_set(&b->nref, 1);
    + b->vec.iov_base = NULL;
    + b->vec.iov_len = 0;
    + b->alloc_len = 0;
    + b->is_static = true;
    +}
    +
    +static inline 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;
    + b->is_static = false;
    + return b;
    +}
    +
    +static inline int ceph_buffer_alloc(struct ceph_buffer *b, int len, gfp_t gfp)
    +{
    + if (len <= PAGE_SIZE) {
    + b->vec.iov_base = kmalloc(len, gfp);
    + 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;
    +}
    +
    +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
    --
    1.5.6.5


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