linux/fs/ceph/export.c
Julia Lawall 7e34bc524e fs/ceph: Use ERR_CAST
Use ERR_CAST(x) rather than ERR_PTR(PTR_ERR(x)).  The former makes more
clear what is the purpose of the operation, which otherwise looks like a
no-op.

In the case of fs/ceph/inode.c, ERR_CAST is not needed, because the type of
the returned value is the same as the type of the enclosing function.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
type T;
T x;
identifier f;
@@

T f (...) { <+...
- ERR_PTR(PTR_ERR(x))
+ x
 ...+> }

@@
expression x;
@@

- ERR_PTR(PTR_ERR(x))
+ ERR_CAST(x)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-29 09:12:41 -07:00

224 lines
5.4 KiB
C

#include "ceph_debug.h"
#include <linux/exportfs.h>
#include <linux/slab.h>
#include <asm/unaligned.h>
#include "super.h"
/*
* NFS export support
*
* NFS re-export of a ceph mount is, at present, only semireliable.
* The basic issue is that the Ceph architectures doesn't lend itself
* well to generating filehandles that will remain valid forever.
*
* So, we do our best. If you're lucky, your inode will be in the
* client's cache. If it's not, and you have a connectable fh, then
* the MDS server may be able to find it for you. Otherwise, you get
* ESTALE.
*
* There are ways to this more reliable, but in the non-connectable fh
* case, we won't every work perfectly, and in the connectable case,
* some changes are needed on the MDS side to work better.
*/
/*
* Basic fh
*/
struct ceph_nfs_fh {
u64 ino;
} __attribute__ ((packed));
/*
* Larger 'connectable' fh that includes parent ino and name hash.
* Use this whenever possible, as it works more reliably.
*/
struct ceph_nfs_confh {
u64 ino, parent_ino;
u32 parent_name_hash;
} __attribute__ ((packed));
static int ceph_encode_fh(struct dentry *dentry, u32 *rawfh, int *max_len,
int connectable)
{
struct ceph_nfs_fh *fh = (void *)rawfh;
struct ceph_nfs_confh *cfh = (void *)rawfh;
struct dentry *parent = dentry->d_parent;
struct inode *inode = dentry->d_inode;
int type;
/* don't re-export snaps */
if (ceph_snap(inode) != CEPH_NOSNAP)
return -EINVAL;
if (*max_len >= sizeof(*cfh)) {
dout("encode_fh %p connectable\n", dentry);
cfh->ino = ceph_ino(dentry->d_inode);
cfh->parent_ino = ceph_ino(parent->d_inode);
cfh->parent_name_hash = parent->d_name.hash;
*max_len = sizeof(*cfh);
type = 2;
} else if (*max_len > sizeof(*fh)) {
if (connectable)
return -ENOSPC;
dout("encode_fh %p\n", dentry);
fh->ino = ceph_ino(dentry->d_inode);
*max_len = sizeof(*fh);
type = 1;
} else {
return -ENOSPC;
}
return type;
}
/*
* convert regular fh to dentry
*
* FIXME: we should try harder by querying the mds for the ino.
*/
static struct dentry *__fh_to_dentry(struct super_block *sb,
struct ceph_nfs_fh *fh)
{
struct inode *inode;
struct dentry *dentry;
struct ceph_vino vino;
int err;
dout("__fh_to_dentry %llx\n", fh->ino);
vino.ino = fh->ino;
vino.snap = CEPH_NOSNAP;
inode = ceph_find_inode(sb, vino);
if (!inode)
return ERR_PTR(-ESTALE);
dentry = d_obtain_alias(inode);
if (IS_ERR(dentry)) {
pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n",
fh->ino, inode);
iput(inode);
return dentry;
}
err = ceph_init_dentry(dentry);
if (err < 0) {
iput(inode);
return ERR_PTR(err);
}
dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry);
return dentry;
}
/*
* convert connectable fh to dentry
*/
static struct dentry *__cfh_to_dentry(struct super_block *sb,
struct ceph_nfs_confh *cfh)
{
struct ceph_mds_client *mdsc = &ceph_sb_to_client(sb)->mdsc;
struct inode *inode;
struct dentry *dentry;
struct ceph_vino vino;
int err;
dout("__cfh_to_dentry %llx (%llx/%x)\n",
cfh->ino, cfh->parent_ino, cfh->parent_name_hash);
vino.ino = cfh->ino;
vino.snap = CEPH_NOSNAP;
inode = ceph_find_inode(sb, vino);
if (!inode) {
struct ceph_mds_request *req;
req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPHASH,
USE_ANY_MDS);
if (IS_ERR(req))
return ERR_CAST(req);
req->r_ino1 = vino;
req->r_ino2.ino = cfh->parent_ino;
req->r_ino2.snap = CEPH_NOSNAP;
req->r_path2 = kmalloc(16, GFP_NOFS);
snprintf(req->r_path2, 16, "%d", cfh->parent_name_hash);
req->r_num_caps = 1;
err = ceph_mdsc_do_request(mdsc, NULL, req);
ceph_mdsc_put_request(req);
inode = ceph_find_inode(sb, vino);
if (!inode)
return ERR_PTR(err ? err : -ESTALE);
}
dentry = d_obtain_alias(inode);
if (IS_ERR(dentry)) {
pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n",
cfh->ino, inode);
iput(inode);
return dentry;
}
err = ceph_init_dentry(dentry);
if (err < 0) {
iput(inode);
return ERR_PTR(err);
}
dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry);
return dentry;
}
static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
if (fh_type == 1)
return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw);
else
return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw);
}
/*
* get parent, if possible.
*
* FIXME: we could do better by querying the mds to discover the
* parent.
*/
static struct dentry *ceph_fh_to_parent(struct super_block *sb,
struct fid *fid,
int fh_len, int fh_type)
{
struct ceph_nfs_confh *cfh = (void *)fid->raw;
struct ceph_vino vino;
struct inode *inode;
struct dentry *dentry;
int err;
if (fh_type == 1)
return ERR_PTR(-ESTALE);
pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino,
cfh->parent_name_hash);
vino.ino = cfh->ino;
vino.snap = CEPH_NOSNAP;
inode = ceph_find_inode(sb, vino);
if (!inode)
return ERR_PTR(-ESTALE);
dentry = d_obtain_alias(inode);
if (IS_ERR(dentry)) {
pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n",
cfh->ino, inode);
iput(inode);
return dentry;
}
err = ceph_init_dentry(dentry);
if (err < 0) {
iput(inode);
return ERR_PTR(err);
}
dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry);
return dentry;
}
const struct export_operations ceph_export_ops = {
.encode_fh = ceph_encode_fh,
.fh_to_dentry = ceph_fh_to_dentry,
.fh_to_parent = ceph_fh_to_parent,
};