From a8e63b7d51cce4557ee7bcd8f51be5cae8547d20 Mon Sep 17 00:00:00 2001 From: Sage Weil Date: Tue, 6 Oct 2009 11:31:13 -0700 Subject: ceph: nfs re-export support Basic NFS re-export support is included. This mostly works. However, Ceph's MDS design precludes the ability to generate a (small) filehandle that will be valid forever, so this is of limited utility. Signed-off-by: Sage Weil --- fs/ceph/export.c | 223 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 223 insertions(+) create mode 100644 fs/ceph/export.c (limited to 'fs/ceph/export.c') diff --git a/fs/ceph/export.c b/fs/ceph/export.c new file mode 100644 index 000000000000..fc68e39cbad6 --- /dev/null +++ b/fs/ceph/export.c @@ -0,0 +1,223 @@ +#include "ceph_debug.h" + +#include +#include + +#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 (!dentry) { + pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n", + fh->ino, inode); + iput(inode); + return ERR_PTR(-ENOMEM); + } + 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_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_PTR(PTR_ERR(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 (!dentry) { + pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n", + cfh->ino, inode); + iput(inode); + return ERR_PTR(-ENOMEM); + } + 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 (!dentry) { + pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n", + cfh->ino, inode); + iput(inode); + return ERR_PTR(-ENOMEM); + } + 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, +}; -- cgit