super.c

Go to the documentation of this file.

#include <linux/ceph/ceph_debug.h>

#include <linux/backing-dev.h>
#include <linux/ctype.h>
#include <linux/fs.h>
#include <linux/inet.h>
#include <linux/in6.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/parser.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/statfs.h>
#include <linux/string.h>

#include "super.h"
#include "mds_client.h"

#include <linux/ceph/ceph_features.h>
#include <linux/ceph/decode.h>
#include <linux/ceph/mon_client.h>
#include <linux/ceph/auth.h>
#include <linux/ceph/debugfs.h>

/*
 * Ceph superblock operations
 *
 * Handle the basics of mounting, unmounting.
 */

/*
 * super ops
 */
static void ceph_put_super(struct super_block *s)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(s);

    dout("put_super\n");
    ceph_mdsc_close_sessions(fsc->mdsc);

    /*
     * ensure we release the bdi before put_anon_super releases
     * the device name.
     */
    if (s->s_bdi == &fsc->backing_dev_info) {
        bdi_unregister(&fsc->backing_dev_info);
        s->s_bdi = NULL;
    }

    return;
}

static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct ceph_fs_client *fsc = ceph_inode_to_client(dentry->d_inode);
    struct ceph_monmap *monmap = fsc->client->monc.monmap;
    struct ceph_statfs st;
    u64 fsid;
    int err;

    dout("statfs\n");
    err = ceph_monc_do_statfs(&fsc->client->monc, &st);
    if (err < 0)
        return err;

    /* fill in kstatfs */
    buf->f_type = CEPH_SUPER_MAGIC;  /* ?? */

    /*
     * express utilization in terms of large blocks to avoid
     * overflow on 32-bit machines.
     */
    buf->f_bsize = 1 << CEPH_BLOCK_SHIFT;
    buf->f_blocks = le64_to_cpu(st.kb) >> (CEPH_BLOCK_SHIFT-10);
    buf->f_bfree = le64_to_cpu(st.kb_avail) >> (CEPH_BLOCK_SHIFT-10);
    buf->f_bavail = le64_to_cpu(st.kb_avail) >> (CEPH_BLOCK_SHIFT-10);

    buf->f_files = le64_to_cpu(st.num_objects);
    buf->f_ffree = -1;
    buf->f_namelen = NAME_MAX;
    buf->f_frsize = PAGE_CACHE_SIZE;

    /* leave fsid little-endian, regardless of host endianness */
    fsid = *(u64 *)(&monmap->fsid) ^ *((u64 *)&monmap->fsid + 1);
    buf->f_fsid.val[0] = fsid & 0xffffffff;
    buf->f_fsid.val[1] = fsid >> 32;

    return 0;
}


static int ceph_sync_fs(struct super_block *sb, int wait)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(sb);

    if (!wait) {
        dout("sync_fs (non-blocking)\n");
        ceph_flush_dirty_caps(fsc->mdsc);
        dout("sync_fs (non-blocking) done\n");
        return 0;
    }

    dout("sync_fs (blocking)\n");
    ceph_osdc_sync(&fsc->client->osdc);
    ceph_mdsc_sync(fsc->mdsc);
    dout("sync_fs (blocking) done\n");
    return 0;
}

/*
 * mount options
 */
enum {
    Opt_wsize,
    Opt_rsize,
    Opt_rasize,
    Opt_caps_wanted_delay_min,
    Opt_caps_wanted_delay_max,
    Opt_cap_release_safety,
    Opt_readdir_max_entries,
    Opt_readdir_max_bytes,
    Opt_congestion_kb,
    Opt_last_int,
    /* int args above */
    Opt_snapdirname,
    Opt_last_string,
    /* string args above */
    Opt_dirstat,
    Opt_nodirstat,
    Opt_rbytes,
    Opt_norbytes,
    Opt_asyncreaddir,
    Opt_noasyncreaddir,
    Opt_dcache,
    Opt_nodcache,
    Opt_ino32,
    Opt_noino32,
};

static match_table_t fsopt_tokens = {
    {Opt_wsize, "wsize=%d"},
    {Opt_rsize, "rsize=%d"},
    {Opt_rasize, "rasize=%d"},
    {Opt_caps_wanted_delay_min, "caps_wanted_delay_min=%d"},
    {Opt_caps_wanted_delay_max, "caps_wanted_delay_max=%d"},
    {Opt_cap_release_safety, "cap_release_safety=%d"},
    {Opt_readdir_max_entries, "readdir_max_entries=%d"},
    {Opt_readdir_max_bytes, "readdir_max_bytes=%d"},
    {Opt_congestion_kb, "write_congestion_kb=%d"},
    /* int args above */
    {Opt_snapdirname, "snapdirname=%s"},
    /* string args above */
    {Opt_dirstat, "dirstat"},
    {Opt_nodirstat, "nodirstat"},
    {Opt_rbytes, "rbytes"},
    {Opt_norbytes, "norbytes"},
    {Opt_asyncreaddir, "asyncreaddir"},
    {Opt_noasyncreaddir, "noasyncreaddir"},
    {Opt_dcache, "dcache"},
    {Opt_nodcache, "nodcache"},
    {Opt_ino32, "ino32"},
    {Opt_noino32, "noino32"},
    {-1, NULL}
};

static int parse_fsopt_token(char *c, void *private)
{
    struct ceph_mount_options *fsopt = private;
    substring_t argstr[MAX_OPT_ARGS];
    int token, intval, ret;

    token = match_token((char *)c, fsopt_tokens, argstr);
    if (token < 0)
        return -EINVAL;

    if (token < Opt_last_int) {
        ret = match_int(&argstr[0], &intval);
        if (ret < 0) {
            pr_err("bad mount option arg (not int) "
                   "at '%s'\n", c);
            return ret;
        }
        dout("got int token %d val %d\n", token, intval);
    } else if (token > Opt_last_int && token < Opt_last_string) {
        dout("got string token %d val %s\n", token,
             argstr[0].from);
    } else {
        dout("got token %d\n", token);
    }

    switch (token) {
    case Opt_snapdirname:
        kfree(fsopt->snapdir_name);
        fsopt->snapdir_name = kstrndup(argstr[0].from,
                           argstr[0].to-argstr[0].from,
                           GFP_KERNEL);
        if (!fsopt->snapdir_name)
            return -ENOMEM;
        break;

        /* misc */
    case Opt_wsize:
        fsopt->wsize = intval;
        break;
    case Opt_rsize:
        fsopt->rsize = intval;
        break;
    case Opt_rasize:
        fsopt->rasize = intval;
        break;
    case Opt_caps_wanted_delay_min:
        fsopt->caps_wanted_delay_min = intval;
        break;
    case Opt_caps_wanted_delay_max:
        fsopt->caps_wanted_delay_max = intval;
        break;
    case Opt_readdir_max_entries:
        fsopt->max_readdir = intval;
        break;
    case Opt_readdir_max_bytes:
        fsopt->max_readdir_bytes = intval;
        break;
    case Opt_congestion_kb:
        fsopt->congestion_kb = intval;
        break;
    case Opt_dirstat:
        fsopt->flags |= CEPH_MOUNT_OPT_DIRSTAT;
        break;
    case Opt_nodirstat:
        fsopt->flags &= ~CEPH_MOUNT_OPT_DIRSTAT;
        break;
    case Opt_rbytes:
        fsopt->flags |= CEPH_MOUNT_OPT_RBYTES;
        break;
    case Opt_norbytes:
        fsopt->flags &= ~CEPH_MOUNT_OPT_RBYTES;
        break;
    case Opt_asyncreaddir:
        fsopt->flags &= ~CEPH_MOUNT_OPT_NOASYNCREADDIR;
        break;
    case Opt_noasyncreaddir:
        fsopt->flags |= CEPH_MOUNT_OPT_NOASYNCREADDIR;
        break;
    case Opt_dcache:
        fsopt->flags |= CEPH_MOUNT_OPT_DCACHE;
        break;
    case Opt_nodcache:
        fsopt->flags &= ~CEPH_MOUNT_OPT_DCACHE;
        break;
    case Opt_ino32:
        fsopt->flags |= CEPH_MOUNT_OPT_INO32;
        break;
    case Opt_noino32:
        fsopt->flags &= ~CEPH_MOUNT_OPT_INO32;
        break;
    default:
        BUG_ON(token);
    }
    return 0;
}

static void destroy_mount_options(struct ceph_mount_options *args)
{
    dout("destroy_mount_options %p\n", args);
    kfree(args->snapdir_name);
    kfree(args);
}

static int strcmp_null(const char *s1, const char *s2)
{
    if (!s1 && !s2)
        return 0;
    if (s1 && !s2)
        return -1;
    if (!s1 && s2)
        return 1;
    return strcmp(s1, s2);
}

static int compare_mount_options(struct ceph_mount_options *new_fsopt,
                 struct ceph_options *new_opt,
                 struct ceph_fs_client *fsc)
{
    struct ceph_mount_options *fsopt1 = new_fsopt;
    struct ceph_mount_options *fsopt2 = fsc->mount_options;
    int ofs = offsetof(struct ceph_mount_options, snapdir_name);
    int ret;

    ret = memcmp(fsopt1, fsopt2, ofs);
    if (ret)
        return ret;

    ret = strcmp_null(fsopt1->snapdir_name, fsopt2->snapdir_name);
    if (ret)
        return ret;

    return ceph_compare_options(new_opt, fsc->client);
}

static int parse_mount_options(struct ceph_mount_options **pfsopt,
                   struct ceph_options **popt,
                   int flags, char *options,
                   const char *dev_name,
                   const char **path)
{
    struct ceph_mount_options *fsopt;
    const char *dev_name_end;
    int err;

    if (!dev_name || !*dev_name)
        return -EINVAL;

    fsopt = kzalloc(sizeof(*fsopt), GFP_KERNEL);
    if (!fsopt)
        return -ENOMEM;

    dout("parse_mount_options %p, dev_name '%s'\n", fsopt, dev_name);

    fsopt->sb_flags = flags;
    fsopt->flags = CEPH_MOUNT_OPT_DEFAULT;

    fsopt->rsize = CEPH_RSIZE_DEFAULT;
    fsopt->rasize = CEPH_RASIZE_DEFAULT;
    fsopt->snapdir_name = kstrdup(CEPH_SNAPDIRNAME_DEFAULT, GFP_KERNEL);
    fsopt->caps_wanted_delay_min = CEPH_CAPS_WANTED_DELAY_MIN_DEFAULT;
    fsopt->caps_wanted_delay_max = CEPH_CAPS_WANTED_DELAY_MAX_DEFAULT;
    fsopt->cap_release_safety = CEPH_CAP_RELEASE_SAFETY_DEFAULT;
    fsopt->max_readdir = CEPH_MAX_READDIR_DEFAULT;
    fsopt->max_readdir_bytes = CEPH_MAX_READDIR_BYTES_DEFAULT;
    fsopt->congestion_kb = default_congestion_kb();

    /*
     * Distinguish the server list from the path in "dev_name".
     * Internally we do not include the leading '/' in the path.
     *
     * "dev_name" will look like:
     *     <server_spec>[,<server_spec>...]:[<path>]
     * where
     *     <server_spec> is <ip>[:<port>]
     *     <path> is optional, but if present must begin with '/'
     */
    dev_name_end = strchr(dev_name, '/');
    if (dev_name_end) {
        /* skip over leading '/' for path */
        *path = dev_name_end + 1;
    } else {
        /* path is empty */
        dev_name_end = dev_name + strlen(dev_name);
        *path = dev_name_end;
    }
    err = -EINVAL;
    dev_name_end--;     /* back up to ':' separator */
    if (*dev_name_end != ':') {
        pr_err("device name is missing path (no : separator in %s)\n",
                dev_name);
        goto out;
    }
    dout("device name '%.*s'\n", (int)(dev_name_end - dev_name), dev_name);
    dout("server path '%s'\n", *path);

    *popt = ceph_parse_options(options, dev_name, dev_name_end,
                 parse_fsopt_token, (void *)fsopt);
    if (IS_ERR(*popt)) {
        err = PTR_ERR(*popt);
        goto out;
    }

    /* success */
    *pfsopt = fsopt;
    return 0;

out:
    destroy_mount_options(fsopt);
    return err;
}

static int ceph_show_options(struct seq_file *m, struct dentry *root)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(root->d_sb);
    struct ceph_mount_options *fsopt = fsc->mount_options;
    struct ceph_options *opt = fsc->client->options;

    if (opt->flags & CEPH_OPT_FSID)
        seq_printf(m, ",fsid=%pU", &opt->fsid);
    if (opt->flags & CEPH_OPT_NOSHARE)
        seq_puts(m, ",noshare");
    if (opt->flags & CEPH_OPT_NOCRC)
        seq_puts(m, ",nocrc");

    if (opt->name)
        seq_printf(m, ",name=%s", opt->name);
    if (opt->key)
        seq_puts(m, ",secret=<hidden>");

    if (opt->mount_timeout != CEPH_MOUNT_TIMEOUT_DEFAULT)
        seq_printf(m, ",mount_timeout=%d", opt->mount_timeout);
    if (opt->osd_idle_ttl != CEPH_OSD_IDLE_TTL_DEFAULT)
        seq_printf(m, ",osd_idle_ttl=%d", opt->osd_idle_ttl);
    if (opt->osd_timeout != CEPH_OSD_TIMEOUT_DEFAULT)
        seq_printf(m, ",osdtimeout=%d", opt->osd_timeout);
    if (opt->osd_keepalive_timeout != CEPH_OSD_KEEPALIVE_DEFAULT)
        seq_printf(m, ",osdkeepalivetimeout=%d",
               opt->osd_keepalive_timeout);

    if (fsopt->flags & CEPH_MOUNT_OPT_DIRSTAT)
        seq_puts(m, ",dirstat");
    if ((fsopt->flags & CEPH_MOUNT_OPT_RBYTES) == 0)
        seq_puts(m, ",norbytes");
    if (fsopt->flags & CEPH_MOUNT_OPT_NOASYNCREADDIR)
        seq_puts(m, ",noasyncreaddir");
    if (fsopt->flags & CEPH_MOUNT_OPT_DCACHE)
        seq_puts(m, ",dcache");
    else
        seq_puts(m, ",nodcache");

    if (fsopt->wsize)
        seq_printf(m, ",wsize=%d", fsopt->wsize);
    if (fsopt->rsize != CEPH_RSIZE_DEFAULT)
        seq_printf(m, ",rsize=%d", fsopt->rsize);
    if (fsopt->rasize != CEPH_RASIZE_DEFAULT)
        seq_printf(m, ",rasize=%d", fsopt->rasize);
    if (fsopt->congestion_kb != default_congestion_kb())
        seq_printf(m, ",write_congestion_kb=%d", fsopt->congestion_kb);
    if (fsopt->caps_wanted_delay_min != CEPH_CAPS_WANTED_DELAY_MIN_DEFAULT)
        seq_printf(m, ",caps_wanted_delay_min=%d",
             fsopt->caps_wanted_delay_min);
    if (fsopt->caps_wanted_delay_max != CEPH_CAPS_WANTED_DELAY_MAX_DEFAULT)
        seq_printf(m, ",caps_wanted_delay_max=%d",
               fsopt->caps_wanted_delay_max);
    if (fsopt->cap_release_safety != CEPH_CAP_RELEASE_SAFETY_DEFAULT)
        seq_printf(m, ",cap_release_safety=%d",
               fsopt->cap_release_safety);
    if (fsopt->max_readdir != CEPH_MAX_READDIR_DEFAULT)
        seq_printf(m, ",readdir_max_entries=%d", fsopt->max_readdir);
    if (fsopt->max_readdir_bytes != CEPH_MAX_READDIR_BYTES_DEFAULT)
        seq_printf(m, ",readdir_max_bytes=%d", fsopt->max_readdir_bytes);
    if (strcmp(fsopt->snapdir_name, CEPH_SNAPDIRNAME_DEFAULT))
        seq_printf(m, ",snapdirname=%s", fsopt->snapdir_name);
    return 0;
}

/*
 * handle any mon messages the standard library doesn't understand.
 * return error if we don't either.
 */
static int extra_mon_dispatch(struct ceph_client *client, struct ceph_msg *msg)
{
    struct ceph_fs_client *fsc = client->private;
    int type = le16_to_cpu(msg->hdr.type);

    switch (type) {
    case CEPH_MSG_MDS_MAP:
        ceph_mdsc_handle_map(fsc->mdsc, msg);
        return 0;

    default:
        return -1;
    }
}

/*
 * create a new fs client
 */
static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
                    struct ceph_options *opt)
{
    struct ceph_fs_client *fsc;
    const unsigned supported_features =
        CEPH_FEATURE_FLOCK |
        CEPH_FEATURE_DIRLAYOUTHASH;
    const unsigned required_features = 0;
    int err = -ENOMEM;

    fsc = kzalloc(sizeof(*fsc), GFP_KERNEL);
    if (!fsc)
        return ERR_PTR(-ENOMEM);

    fsc->client = ceph_create_client(opt, fsc, supported_features,
                     required_features);
    if (IS_ERR(fsc->client)) {
        err = PTR_ERR(fsc->client);
        goto fail;
    }
    fsc->client->extra_mon_dispatch = extra_mon_dispatch;
    fsc->client->monc.want_mdsmap = 1;

    fsc->mount_options = fsopt;

    fsc->sb = NULL;
    fsc->mount_state = CEPH_MOUNT_MOUNTING;

    atomic_long_set(&fsc->writeback_count, 0);

    err = bdi_init(&fsc->backing_dev_info);
    if (err < 0)
        goto fail_client;

    err = -ENOMEM;
    /*
     * The number of concurrent works can be high but they don't need
     * to be processed in parallel, limit concurrency.
     */
    fsc->wb_wq = alloc_workqueue("ceph-writeback", 0, 1);
    if (fsc->wb_wq == NULL)
        goto fail_bdi;
    fsc->pg_inv_wq = alloc_workqueue("ceph-pg-invalid", 0, 1);
    if (fsc->pg_inv_wq == NULL)
        goto fail_wb_wq;
    fsc->trunc_wq = alloc_workqueue("ceph-trunc", 0, 1);
    if (fsc->trunc_wq == NULL)
        goto fail_pg_inv_wq;

    /* set up mempools */
    err = -ENOMEM;
    fsc->wb_pagevec_pool = mempool_create_kmalloc_pool(10,
                  fsc->mount_options->wsize >> PAGE_CACHE_SHIFT);
    if (!fsc->wb_pagevec_pool)
        goto fail_trunc_wq;

    /* caps */
    fsc->min_caps = fsopt->max_readdir;

    return fsc;

fail_trunc_wq:
    destroy_workqueue(fsc->trunc_wq);
fail_pg_inv_wq:
    destroy_workqueue(fsc->pg_inv_wq);
fail_wb_wq:
    destroy_workqueue(fsc->wb_wq);
fail_bdi:
    bdi_destroy(&fsc->backing_dev_info);
fail_client:
    ceph_destroy_client(fsc->client);
fail:
    kfree(fsc);
    return ERR_PTR(err);
}

static void destroy_fs_client(struct ceph_fs_client *fsc)
{
    dout("destroy_fs_client %p\n", fsc);

    destroy_workqueue(fsc->wb_wq);
    destroy_workqueue(fsc->pg_inv_wq);
    destroy_workqueue(fsc->trunc_wq);

    bdi_destroy(&fsc->backing_dev_info);

    mempool_destroy(fsc->wb_pagevec_pool);

    destroy_mount_options(fsc->mount_options);

    ceph_fs_debugfs_cleanup(fsc);

    ceph_destroy_client(fsc->client);

    kfree(fsc);
    dout("destroy_fs_client %p done\n", fsc);
}

/*
 * caches
 */
struct kmem_cache *ceph_inode_cachep;
struct kmem_cache *ceph_cap_cachep;
struct kmem_cache *ceph_dentry_cachep;
struct kmem_cache *ceph_file_cachep;

static void ceph_inode_init_once(void *foo)
{
    struct ceph_inode_info *ci = foo;
    inode_init_once(&ci->vfs_inode);
}

static int __init init_caches(void)
{
    ceph_inode_cachep = kmem_cache_create("ceph_inode_info",
                      sizeof(struct ceph_inode_info),
                      __alignof__(struct ceph_inode_info),
                      (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD),
                      ceph_inode_init_once);
    if (ceph_inode_cachep == NULL)
        return -ENOMEM;

    ceph_cap_cachep = KMEM_CACHE(ceph_cap,
                     SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD);
    if (ceph_cap_cachep == NULL)
        goto bad_cap;

    ceph_dentry_cachep = KMEM_CACHE(ceph_dentry_info,
                    SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD);
    if (ceph_dentry_cachep == NULL)
        goto bad_dentry;

    ceph_file_cachep = KMEM_CACHE(ceph_file_info,
                      SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD);
    if (ceph_file_cachep == NULL)
        goto bad_file;

    return 0;

bad_file:
    kmem_cache_destroy(ceph_dentry_cachep);
bad_dentry:
    kmem_cache_destroy(ceph_cap_cachep);
bad_cap:
    kmem_cache_destroy(ceph_inode_cachep);
    return -ENOMEM;
}

static void destroy_caches(void)
{
    /*
     * Make sure all delayed rcu free inodes are flushed before we
     * destroy cache.
     */
    rcu_barrier();
    kmem_cache_destroy(ceph_inode_cachep);
    kmem_cache_destroy(ceph_cap_cachep);
    kmem_cache_destroy(ceph_dentry_cachep);
    kmem_cache_destroy(ceph_file_cachep);
}


/*
 * ceph_umount_begin - initiate forced umount.  Tear down down the
 * mount, skipping steps that may hang while waiting for server(s).
 */
static void ceph_umount_begin(struct super_block *sb)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(sb);

    dout("ceph_umount_begin - starting forced umount\n");
    if (!fsc)
        return;
    fsc->mount_state = CEPH_MOUNT_SHUTDOWN;
    return;
}

static const struct super_operations ceph_super_ops = {
    .alloc_inode    = ceph_alloc_inode,
    .destroy_inode  = ceph_destroy_inode,
    .write_inode    = ceph_write_inode,
    .sync_fs        = ceph_sync_fs,
    .put_super  = ceph_put_super,
    .show_options   = ceph_show_options,
    .statfs     = ceph_statfs,
    .umount_begin   = ceph_umount_begin,
};

/*
 * Bootstrap mount by opening the root directory.  Note the mount
 * @started time from caller, and time out if this takes too long.
 */
static struct dentry *open_root_dentry(struct ceph_fs_client *fsc,
                       const char *path,
                       unsigned long started)
{
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct ceph_mds_request *req = NULL;
    int err;
    struct dentry *root;

    /* open dir */
    dout("open_root_inode opening '%s'\n", path);
    req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_GETATTR, USE_ANY_MDS);
    if (IS_ERR(req))
        return ERR_CAST(req);
    req->r_path1 = kstrdup(path, GFP_NOFS);
    req->r_ino1.ino = CEPH_INO_ROOT;
    req->r_ino1.snap = CEPH_NOSNAP;
    req->r_started = started;
    req->r_timeout = fsc->client->options->mount_timeout * HZ;
    req->r_args.getattr.mask = cpu_to_le32(CEPH_STAT_CAP_INODE);
    req->r_num_caps = 2;
    err = ceph_mdsc_do_request(mdsc, NULL, req);
    if (err == 0) {
        struct inode *inode = req->r_target_inode;
        req->r_target_inode = NULL;
        dout("open_root_inode success\n");
        if (ceph_ino(inode) == CEPH_INO_ROOT &&
            fsc->sb->s_root == NULL) {
            root = d_make_root(inode);
            if (!root) {
                root = ERR_PTR(-ENOMEM);
                goto out;
            }
        } else {
            root = d_obtain_alias(inode);
        }
        ceph_init_dentry(root);
        dout("open_root_inode success, root dentry is %p\n", root);
    } else {
        root = ERR_PTR(err);
    }
out:
    ceph_mdsc_put_request(req);
    return root;
}




/*
 * mount: join the ceph cluster, and open root directory.
 */
static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc,
              const char *path)
{
    int err;
    unsigned long started = jiffies;  /* note the start time */
    struct dentry *root;
    int first = 0;   /* first vfsmount for this super_block */

    dout("mount start\n");
    mutex_lock(&fsc->client->mount_mutex);

    err = __ceph_open_session(fsc->client, started);
    if (err < 0)
        goto out;

    dout("mount opening root\n");
    root = open_root_dentry(fsc, "", started);
    if (IS_ERR(root)) {
        err = PTR_ERR(root);
        goto out;
    }
    if (fsc->sb->s_root) {
        dput(root);
    } else {
        fsc->sb->s_root = root;
        first = 1;

        err = ceph_fs_debugfs_init(fsc);
        if (err < 0)
            goto fail;
    }

    if (path[0] == 0) {
        dget(root);
    } else {
        dout("mount opening base mountpoint\n");
        root = open_root_dentry(fsc, path, started);
        if (IS_ERR(root)) {
            err = PTR_ERR(root);
            goto fail;
        }
    }

    fsc->mount_state = CEPH_MOUNT_MOUNTED;
    dout("mount success\n");
    mutex_unlock(&fsc->client->mount_mutex);
    return root;

out:
    mutex_unlock(&fsc->client->mount_mutex);
    return ERR_PTR(err);

fail:
    if (first) {
        dput(fsc->sb->s_root);
        fsc->sb->s_root = NULL;
    }
    goto out;
}

static int ceph_set_super(struct super_block *s, void *data)
{
    struct ceph_fs_client *fsc = data;
    int ret;

    dout("set_super %p data %p\n", s, data);

    s->s_flags = fsc->mount_options->sb_flags;
    s->s_maxbytes = 1ULL << 40;  /* temp value until we get mdsmap */

    s->s_fs_info = fsc;
    fsc->sb = s;

    s->s_op = &ceph_super_ops;
    s->s_export_op = &ceph_export_ops;

    s->s_time_gran = 1000;  /* 1000 ns == 1 us */

    ret = set_anon_super(s, NULL);  /* what is that second arg for? */
    if (ret != 0)
        goto fail;

    return ret;

fail:
    s->s_fs_info = NULL;
    fsc->sb = NULL;
    return ret;
}

/*
 * share superblock if same fs AND options
 */
static int ceph_compare_super(struct super_block *sb, void *data)
{
    struct ceph_fs_client *new = data;
    struct ceph_mount_options *fsopt = new->mount_options;
    struct ceph_options *opt = new->client->options;
    struct ceph_fs_client *other = ceph_sb_to_client(sb);

    dout("ceph_compare_super %p\n", sb);

    if (compare_mount_options(fsopt, opt, other)) {
        dout("monitor(s)/mount options don't match\n");
        return 0;
    }
    if ((opt->flags & CEPH_OPT_FSID) &&
        ceph_fsid_compare(&opt->fsid, &other->client->fsid)) {
        dout("fsid doesn't match\n");
        return 0;
    }
    if (fsopt->sb_flags != other->mount_options->sb_flags) {
        dout("flags differ\n");
        return 0;
    }
    return 1;
}

/*
 * construct our own bdi so we can control readahead, etc.
 */
static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);

static int ceph_register_bdi(struct super_block *sb,
                 struct ceph_fs_client *fsc)
{
    int err;

    /* set ra_pages based on rasize mount option? */
    if (fsc->mount_options->rasize >= PAGE_CACHE_SIZE)
        fsc->backing_dev_info.ra_pages =
            (fsc->mount_options->rasize + PAGE_CACHE_SIZE - 1)
            >> PAGE_SHIFT;
    else
        fsc->backing_dev_info.ra_pages =
            default_backing_dev_info.ra_pages;

    err = bdi_register(&fsc->backing_dev_info, NULL, "ceph-%d",
               atomic_long_inc_return(&bdi_seq));
    if (!err)
        sb->s_bdi = &fsc->backing_dev_info;
    return err;
}

static struct dentry *ceph_mount(struct file_system_type *fs_type,
               int flags, const char *dev_name, void *data)
{
    struct super_block *sb;
    struct ceph_fs_client *fsc;
    struct dentry *res;
    int err;
    int (*compare_super)(struct super_block *, void *) = ceph_compare_super;
    const char *path = NULL;
    struct ceph_mount_options *fsopt = NULL;
    struct ceph_options *opt = NULL;

    dout("ceph_mount\n");
    err = parse_mount_options(&fsopt, &opt, flags, data, dev_name, &path);
    if (err < 0) {
        res = ERR_PTR(err);
        goto out_final;
    }

    /* create client (which we may/may not use) */
    fsc = create_fs_client(fsopt, opt);
    if (IS_ERR(fsc)) {
        res = ERR_CAST(fsc);
        destroy_mount_options(fsopt);
        ceph_destroy_options(opt);
        goto out_final;
    }

    err = ceph_mdsc_init(fsc);
    if (err < 0) {
        res = ERR_PTR(err);
        goto out;
    }

    if (ceph_test_opt(fsc->client, NOSHARE))
        compare_super = NULL;
    sb = sget(fs_type, compare_super, ceph_set_super, flags, fsc);
    if (IS_ERR(sb)) {
        res = ERR_CAST(sb);
        goto out;
    }

    if (ceph_sb_to_client(sb) != fsc) {
        ceph_mdsc_destroy(fsc);
        destroy_fs_client(fsc);
        fsc = ceph_sb_to_client(sb);
        dout("get_sb got existing client %p\n", fsc);
    } else {
        dout("get_sb using new client %p\n", fsc);
        err = ceph_register_bdi(sb, fsc);
        if (err < 0) {
            res = ERR_PTR(err);
            goto out_splat;
        }
    }

    res = ceph_real_mount(fsc, path);
    if (IS_ERR(res))
        goto out_splat;
    dout("root %p inode %p ino %llx.%llx\n", res,
         res->d_inode, ceph_vinop(res->d_inode));
    return res;

out_splat:
    ceph_mdsc_close_sessions(fsc->mdsc);
    deactivate_locked_super(sb);
    goto out_final;

out:
    ceph_mdsc_destroy(fsc);
    destroy_fs_client(fsc);
out_final:
    dout("ceph_mount fail %ld\n", PTR_ERR(res));
    return res;
}

static void ceph_kill_sb(struct super_block *s)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(s);
    dout("kill_sb %p\n", s);
    ceph_mdsc_pre_umount(fsc->mdsc);
    kill_anon_super(s);    /* will call put_super after sb is r/o */
    ceph_mdsc_destroy(fsc);
    destroy_fs_client(fsc);
}

static struct file_system_type ceph_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "ceph",
    .mount      = ceph_mount,
    .kill_sb    = ceph_kill_sb,
    .fs_flags   = FS_RENAME_DOES_D_MOVE,
};

#define _STRINGIFY(x) #x
#define STRINGIFY(x) _STRINGIFY(x)

static int __init init_ceph(void)
{
    int ret = init_caches();
    if (ret)
        goto out;

    ceph_xattr_init();
    ret = register_filesystem(&ceph_fs_type);
    if (ret)
        goto out_icache;

    pr_info("loaded (mds proto %d)\n", CEPH_MDSC_PROTOCOL);

    return 0;

out_icache:
    ceph_xattr_exit();
    destroy_caches();
out:
    return ret;
}

static void __exit exit_ceph(void)
{
    dout("exit_ceph\n");
    unregister_filesystem(&ceph_fs_type);
    ceph_xattr_exit();
    destroy_caches();
}

module_init(init_ceph);
module_exit(exit_ceph);

MODULE_AUTHOR("Sage Weil <[email protected]>");
MODULE_AUTHOR("Yehuda Sadeh <[email protected]>");
MODULE_AUTHOR("Patience Warnick <[email protected]>");
MODULE_DESCRIPTION("Ceph filesystem for Linux");
MODULE_LICENSE("GPL");