Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

[linux-stable.git] / fs / ceph / super.c

// SPDX-License-Identifier: GPL-2.0-only

#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/fs_context.h>
#include <linux/fs_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 "cache.h"
#include "crypto.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>

#include <uapi/linux/magic.h>

static DEFINE_SPINLOCK(ceph_fsc_lock);
static LIST_HEAD(ceph_fsc_list);

/*
 * 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_fs_client(s);

        doutc(fsc->client, "begin\n");
        ceph_fscrypt_free_dummy_policy(fsc);
        ceph_mdsc_close_sessions(fsc->mdsc);
        doutc(fsc->client, "done\n");
}

static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf)
{
        struct ceph_fs_client *fsc = ceph_inode_to_fs_client(d_inode(dentry));
        struct ceph_mon_client *monc = &fsc->client->monc;
        struct ceph_statfs st;
        int i, err;
        u64 data_pool;

        doutc(fsc->client, "begin\n");
        if (fsc->mdsc->mdsmap->m_num_data_pg_pools == 1) {
                data_pool = fsc->mdsc->mdsmap->m_data_pg_pools[0];
        } else {
                data_pool = CEPH_NOPOOL;
        }

        err = ceph_monc_do_statfs(monc, data_pool, &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_frsize = 1 << CEPH_BLOCK_SHIFT;

        /*
         * By default use root quota for stats; fallback to overall filesystem
         * usage if using 'noquotadf' mount option or if the root dir doesn't
         * have max_bytes quota set.
         */
        if (ceph_test_mount_opt(fsc, NOQUOTADF) ||
            !ceph_quota_update_statfs(fsc, buf)) {
                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);
        }

        /*
         * NOTE: for the time being, we make bsize == frsize to humor
         * not-yet-ancient versions of glibc that are broken.
         * Someday, we will probably want to report a real block
         * size...  whatever that may mean for a network file system!
         */
        buf->f_bsize = buf->f_frsize;

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

        /* Must convert the fsid, for consistent values across arches */
        buf->f_fsid.val[0] = 0;
        mutex_lock(&monc->mutex);
        for (i = 0 ; i < sizeof(monc->monmap->fsid) / sizeof(__le32) ; ++i)
                buf->f_fsid.val[0] ^= le32_to_cpu(((__le32 *)&monc->monmap->fsid)[i]);
        mutex_unlock(&monc->mutex);

        /* fold the fs_cluster_id into the upper bits */
        buf->f_fsid.val[1] = monc->fs_cluster_id;

        doutc(fsc->client, "done\n");
        return 0;
}

static int ceph_sync_fs(struct super_block *sb, int wait)
{
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);
        struct ceph_client *cl = fsc->client;

        if (!wait) {
                doutc(cl, "(non-blocking)\n");
                ceph_flush_dirty_caps(fsc->mdsc);
                ceph_flush_cap_releases(fsc->mdsc);
                doutc(cl, "(non-blocking) done\n");
                return 0;
        }

        doutc(cl, "(blocking)\n");
        ceph_osdc_sync(&fsc->client->osdc);
        ceph_mdsc_sync(fsc->mdsc);
        doutc(cl, "(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_caps_max,
        Opt_readdir_max_entries,
        Opt_readdir_max_bytes,
        Opt_congestion_kb,
        /* int args above */
        Opt_snapdirname,
        Opt_mds_namespace,
        Opt_recover_session,
        Opt_source,
        Opt_mon_addr,
        Opt_test_dummy_encryption,
        /* string args above */
        Opt_dirstat,
        Opt_rbytes,
        Opt_asyncreaddir,
        Opt_dcache,
        Opt_ino32,
        Opt_fscache,
        Opt_poolperm,
        Opt_require_active_mds,
        Opt_acl,
        Opt_quotadf,
        Opt_copyfrom,
        Opt_wsync,
        Opt_pagecache,
        Opt_sparseread,
};

enum ceph_recover_session_mode {
        ceph_recover_session_no,
        ceph_recover_session_clean
};

static const struct constant_table ceph_param_recover[] = {
        { "no",         ceph_recover_session_no },
        { "clean",      ceph_recover_session_clean },
        {}
};

static const struct fs_parameter_spec ceph_mount_parameters[] = {
        fsparam_flag_no ("acl",                         Opt_acl),
        fsparam_flag_no ("asyncreaddir",                Opt_asyncreaddir),
        fsparam_s32     ("caps_max",                    Opt_caps_max),
        fsparam_u32     ("caps_wanted_delay_max",       Opt_caps_wanted_delay_max),
        fsparam_u32     ("caps_wanted_delay_min",       Opt_caps_wanted_delay_min),
        fsparam_u32     ("write_congestion_kb",         Opt_congestion_kb),
        fsparam_flag_no ("copyfrom",                    Opt_copyfrom),
        fsparam_flag_no ("dcache",                      Opt_dcache),
        fsparam_flag_no ("dirstat",                     Opt_dirstat),
        fsparam_flag_no ("fsc",                         Opt_fscache), // fsc|nofsc
        fsparam_string  ("fsc",                         Opt_fscache), // fsc=...
        fsparam_flag_no ("ino32",                       Opt_ino32),
        fsparam_string  ("mds_namespace",               Opt_mds_namespace),
        fsparam_string  ("mon_addr",                    Opt_mon_addr),
        fsparam_flag_no ("poolperm",                    Opt_poolperm),
        fsparam_flag_no ("quotadf",                     Opt_quotadf),
        fsparam_u32     ("rasize",                      Opt_rasize),
        fsparam_flag_no ("rbytes",                      Opt_rbytes),
        fsparam_u32     ("readdir_max_bytes",           Opt_readdir_max_bytes),
        fsparam_u32     ("readdir_max_entries",         Opt_readdir_max_entries),
        fsparam_enum    ("recover_session",             Opt_recover_session, ceph_param_recover),
        fsparam_flag_no ("require_active_mds",          Opt_require_active_mds),
        fsparam_u32     ("rsize",                       Opt_rsize),
        fsparam_string  ("snapdirname",                 Opt_snapdirname),
        fsparam_string  ("source",                      Opt_source),
        fsparam_flag    ("test_dummy_encryption",       Opt_test_dummy_encryption),
        fsparam_string  ("test_dummy_encryption",       Opt_test_dummy_encryption),
        fsparam_u32     ("wsize",                       Opt_wsize),
        fsparam_flag_no ("wsync",                       Opt_wsync),
        fsparam_flag_no ("pagecache",                   Opt_pagecache),
        fsparam_flag_no ("sparseread",                  Opt_sparseread),
        {}
};

struct ceph_parse_opts_ctx {
        struct ceph_options             *copts;
        struct ceph_mount_options       *opts;
};

/*
 * Remove adjacent slashes and then the trailing slash, unless it is
 * the only remaining character.
 *
 * E.g. "//dir1////dir2///" --> "/dir1/dir2", "///" --> "/".
 */
static void canonicalize_path(char *path)
{
        int i, j = 0;

        for (i = 0; path[i] != '\0'; i++) {
                if (path[i] != '/' || j < 1 || path[j - 1] != '/')
                        path[j++] = path[i];
        }

        if (j > 1 && path[j - 1] == '/')
                j--;
        path[j] = '\0';
}

/*
 * Check if the mds namespace in ceph_mount_options matches
 * the passed in namespace string. First time match (when
 * ->mds_namespace is NULL) is treated specially, since
 * ->mds_namespace needs to be initialized by the caller.
 */
static int namespace_equals(struct ceph_mount_options *fsopt,
                            const char *namespace, size_t len)
{
        return !(fsopt->mds_namespace &&
                 (strlen(fsopt->mds_namespace) != len ||
                  strncmp(fsopt->mds_namespace, namespace, len)));
}

static int ceph_parse_old_source(const char *dev_name, const char *dev_name_end,
                                 struct fs_context *fc)
{
        int r;
        struct ceph_parse_opts_ctx *pctx = fc->fs_private;
        struct ceph_mount_options *fsopt = pctx->opts;

        if (*dev_name_end != ':')
                return invalfc(fc, "separator ':' missing in source");

        r = ceph_parse_mon_ips(dev_name, dev_name_end - dev_name,
                               pctx->copts, fc->log.log, ',');
        if (r)
                return r;

        fsopt->new_dev_syntax = false;
        return 0;
}

static int ceph_parse_new_source(const char *dev_name, const char *dev_name_end,
                                 struct fs_context *fc)
{
        size_t len;
        struct ceph_fsid fsid;
        struct ceph_parse_opts_ctx *pctx = fc->fs_private;
        struct ceph_options *opts = pctx->copts;
        struct ceph_mount_options *fsopt = pctx->opts;
        const char *name_start = dev_name;
        const char *fsid_start, *fs_name_start;

        if (*dev_name_end != '=') {
                dout("separator '=' missing in source");
                return -EINVAL;
        }

        fsid_start = strchr(dev_name, '@');
        if (!fsid_start)
                return invalfc(fc, "missing cluster fsid");
        len = fsid_start - name_start;
        kfree(opts->name);
        opts->name = kstrndup(name_start, len, GFP_KERNEL);
        if (!opts->name)
                return -ENOMEM;
        dout("using %s entity name", opts->name);

        ++fsid_start; /* start of cluster fsid */
        fs_name_start = strchr(fsid_start, '.');
        if (!fs_name_start)
                return invalfc(fc, "missing file system name");

        if (ceph_parse_fsid(fsid_start, &fsid))
                return invalfc(fc, "Invalid FSID");

        ++fs_name_start; /* start of file system name */
        len = dev_name_end - fs_name_start;

        if (!namespace_equals(fsopt, fs_name_start, len))
                return invalfc(fc, "Mismatching mds_namespace");
        kfree(fsopt->mds_namespace);
        fsopt->mds_namespace = kstrndup(fs_name_start, len, GFP_KERNEL);
        if (!fsopt->mds_namespace)
                return -ENOMEM;
        dout("file system (mds namespace) '%s'\n", fsopt->mds_namespace);

        fsopt->new_dev_syntax = true;
        return 0;
}

/*
 * Parse the source parameter for new device format. Distinguish the device
 * spec from the path. Try parsing new device format and fallback to old
 * format if needed.
 *
 * New device syntax will looks like:
 *     <device_spec>=/<path>
 * where
 *     <device_spec> is name@fsid.fsname
 *     <path> is optional, but if present must begin with '/'
 * (monitor addresses are passed via mount option)
 *
 * Old device syntax is:
 *     <server_spec>[,<server_spec>...]:[<path>]
 * where
 *     <server_spec> is <ip>[:<port>]
 *     <path> is optional, but if present must begin with '/'
 */
static int ceph_parse_source(struct fs_parameter *param, struct fs_context *fc)
{
        struct ceph_parse_opts_ctx *pctx = fc->fs_private;
        struct ceph_mount_options *fsopt = pctx->opts;
        char *dev_name = param->string, *dev_name_end;
        int ret;

        dout("'%s'\n", dev_name);
        if (!dev_name || !*dev_name)
                return invalfc(fc, "Empty source");

        dev_name_end = strchr(dev_name, '/');
        if (dev_name_end) {
                /*
                 * The server_path will include the whole chars from userland
                 * including the leading '/'.
                 */
                kfree(fsopt->server_path);
                fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL);
                if (!fsopt->server_path)
                        return -ENOMEM;

                canonicalize_path(fsopt->server_path);
        } else {
                dev_name_end = dev_name + strlen(dev_name);
        }

        dev_name_end--;         /* back up to separator */
        if (dev_name_end < dev_name)
                return invalfc(fc, "Path missing in source");

        dout("device name '%.*s'\n", (int)(dev_name_end - dev_name), dev_name);
        if (fsopt->server_path)
                dout("server path '%s'\n", fsopt->server_path);

        dout("trying new device syntax");
        ret = ceph_parse_new_source(dev_name, dev_name_end, fc);
        if (ret) {
                if (ret != -EINVAL)
                        return ret;
                dout("trying old device syntax");
                ret = ceph_parse_old_source(dev_name, dev_name_end, fc);
                if (ret)
                        return ret;
        }

        fc->source = param->string;
        param->string = NULL;
        return 0;
}

static int ceph_parse_mon_addr(struct fs_parameter *param,
                               struct fs_context *fc)
{
        struct ceph_parse_opts_ctx *pctx = fc->fs_private;
        struct ceph_mount_options *fsopt = pctx->opts;

        kfree(fsopt->mon_addr);
        fsopt->mon_addr = param->string;
        param->string = NULL;

        return ceph_parse_mon_ips(fsopt->mon_addr, strlen(fsopt->mon_addr),
                                  pctx->copts, fc->log.log, '/');
}

static int ceph_parse_mount_param(struct fs_context *fc,
                                  struct fs_parameter *param)
{
        struct ceph_parse_opts_ctx *pctx = fc->fs_private;
        struct ceph_mount_options *fsopt = pctx->opts;
        struct fs_parse_result result;
        unsigned int mode;
        int token, ret;

        ret = ceph_parse_param(param, pctx->copts, fc->log.log);
        if (ret != -ENOPARAM)
                return ret;

        token = fs_parse(fc, ceph_mount_parameters, param, &result);
        dout("%s: fs_parse '%s' token %d\n",__func__, param->key, token);
        if (token < 0)
                return token;

        switch (token) {
        case Opt_snapdirname:
                if (strlen(param->string) > NAME_MAX)
                        return invalfc(fc, "snapdirname too long");
                kfree(fsopt->snapdir_name);
                fsopt->snapdir_name = param->string;
                param->string = NULL;
                break;
        case Opt_mds_namespace:
                if (!namespace_equals(fsopt, param->string, strlen(param->string)))
                        return invalfc(fc, "Mismatching mds_namespace");
                kfree(fsopt->mds_namespace);
                fsopt->mds_namespace = param->string;
                param->string = NULL;
                break;
        case Opt_recover_session:
                mode = result.uint_32;
                if (mode == ceph_recover_session_no)
                        fsopt->flags &= ~CEPH_MOUNT_OPT_CLEANRECOVER;
                else if (mode == ceph_recover_session_clean)
                        fsopt->flags |= CEPH_MOUNT_OPT_CLEANRECOVER;
                else
                        BUG();
                break;
        case Opt_source:
                if (fc->source)
                        return invalfc(fc, "Multiple sources specified");
                return ceph_parse_source(param, fc);
        case Opt_mon_addr:
                return ceph_parse_mon_addr(param, fc);
        case Opt_wsize:
                if (result.uint_32 < PAGE_SIZE ||
                    result.uint_32 > CEPH_MAX_WRITE_SIZE)
                        goto out_of_range;
                fsopt->wsize = ALIGN(result.uint_32, PAGE_SIZE);
                break;
        case Opt_rsize:
                if (result.uint_32 < PAGE_SIZE ||
                    result.uint_32 > CEPH_MAX_READ_SIZE)
                        goto out_of_range;
                fsopt->rsize = ALIGN(result.uint_32, PAGE_SIZE);
                break;
        case Opt_rasize:
                fsopt->rasize = ALIGN(result.uint_32, PAGE_SIZE);
                break;
        case Opt_caps_wanted_delay_min:
                if (result.uint_32 < 1)
                        goto out_of_range;
                fsopt->caps_wanted_delay_min = result.uint_32;
                break;
        case Opt_caps_wanted_delay_max:
                if (result.uint_32 < 1)
                        goto out_of_range;
                fsopt->caps_wanted_delay_max = result.uint_32;
                break;
        case Opt_caps_max:
                if (result.int_32 < 0)
                        goto out_of_range;
                fsopt->caps_max = result.int_32;
                break;
        case Opt_readdir_max_entries:
                if (result.uint_32 < 1)
                        goto out_of_range;
                fsopt->max_readdir = result.uint_32;
                break;
        case Opt_readdir_max_bytes:
                if (result.uint_32 < PAGE_SIZE && result.uint_32 != 0)
                        goto out_of_range;
                fsopt->max_readdir_bytes = result.uint_32;
                break;
        case Opt_congestion_kb:
                if (result.uint_32 < 1024) /* at least 1M */
                        goto out_of_range;
                fsopt->congestion_kb = result.uint_32;
                break;
        case Opt_dirstat:
                if (!result.negated)
                        fsopt->flags |= CEPH_MOUNT_OPT_DIRSTAT;
                else
                        fsopt->flags &= ~CEPH_MOUNT_OPT_DIRSTAT;
                break;
        case Opt_rbytes:
                if (!result.negated)
                        fsopt->flags |= CEPH_MOUNT_OPT_RBYTES;
                else
                        fsopt->flags &= ~CEPH_MOUNT_OPT_RBYTES;
                break;
        case Opt_asyncreaddir:
                if (!result.negated)
                        fsopt->flags &= ~CEPH_MOUNT_OPT_NOASYNCREADDIR;
                else
                        fsopt->flags |= CEPH_MOUNT_OPT_NOASYNCREADDIR;
                break;
        case Opt_dcache:
                if (!result.negated)
                        fsopt->flags |= CEPH_MOUNT_OPT_DCACHE;
                else
                        fsopt->flags &= ~CEPH_MOUNT_OPT_DCACHE;
                break;
        case Opt_ino32:
                if (!result.negated)
                        fsopt->flags |= CEPH_MOUNT_OPT_INO32;
                else
                        fsopt->flags &= ~CEPH_MOUNT_OPT_INO32;
                break;

        case Opt_fscache:
#ifdef CONFIG_CEPH_FSCACHE
                kfree(fsopt->fscache_uniq);
                fsopt->fscache_uniq = NULL;
                if (result.negated) {
                        fsopt->flags &= ~CEPH_MOUNT_OPT_FSCACHE;
                } else {
                        fsopt->flags |= CEPH_MOUNT_OPT_FSCACHE;
                        fsopt->fscache_uniq = param->string;
                        param->string = NULL;
                }
                break;
#else
                return invalfc(fc, "fscache support is disabled");
#endif
        case Opt_poolperm:
                if (!result.negated)
                        fsopt->flags &= ~CEPH_MOUNT_OPT_NOPOOLPERM;
                else
                        fsopt->flags |= CEPH_MOUNT_OPT_NOPOOLPERM;
                break;
        case Opt_require_active_mds:
                if (!result.negated)
                        fsopt->flags &= ~CEPH_MOUNT_OPT_MOUNTWAIT;
                else
                        fsopt->flags |= CEPH_MOUNT_OPT_MOUNTWAIT;
                break;
        case Opt_quotadf:
                if (!result.negated)
                        fsopt->flags &= ~CEPH_MOUNT_OPT_NOQUOTADF;
                else
                        fsopt->flags |= CEPH_MOUNT_OPT_NOQUOTADF;
                break;
        case Opt_copyfrom:
                if (!result.negated)
                        fsopt->flags &= ~CEPH_MOUNT_OPT_NOCOPYFROM;
                else
                        fsopt->flags |= CEPH_MOUNT_OPT_NOCOPYFROM;
                break;
        case Opt_acl:
                if (!result.negated) {
#ifdef CONFIG_CEPH_FS_POSIX_ACL
                        fc->sb_flags |= SB_POSIXACL;
#else
                        return invalfc(fc, "POSIX ACL support is disabled");
#endif
                } else {
                        fc->sb_flags &= ~SB_POSIXACL;
                }
                break;
        case Opt_wsync:
                if (!result.negated)
                        fsopt->flags &= ~CEPH_MOUNT_OPT_ASYNC_DIROPS;
                else
                        fsopt->flags |= CEPH_MOUNT_OPT_ASYNC_DIROPS;
                break;
        case Opt_pagecache:
                if (result.negated)
                        fsopt->flags |= CEPH_MOUNT_OPT_NOPAGECACHE;
                else
                        fsopt->flags &= ~CEPH_MOUNT_OPT_NOPAGECACHE;
                break;
        case Opt_sparseread:
                if (result.negated)
                        fsopt->flags &= ~CEPH_MOUNT_OPT_SPARSEREAD;
                else
                        fsopt->flags |= CEPH_MOUNT_OPT_SPARSEREAD;
                break;
        case Opt_test_dummy_encryption:
#ifdef CONFIG_FS_ENCRYPTION
                fscrypt_free_dummy_policy(&fsopt->dummy_enc_policy);
                ret = fscrypt_parse_test_dummy_encryption(param,
                                                &fsopt->dummy_enc_policy);
                if (ret == -EINVAL) {
                        warnfc(fc, "Value of option \"%s\" is unrecognized",
                               param->key);
                } else if (ret == -EEXIST) {
                        warnfc(fc, "Conflicting test_dummy_encryption options");
                        ret = -EINVAL;
                }
#else
                warnfc(fc,
                       "FS encryption not supported: test_dummy_encryption mount option ignored");
#endif
                break;
        default:
                BUG();
        }
        return 0;

out_of_range:
        return invalfc(fc, "%s out of range", param->key);
}

static void destroy_mount_options(struct ceph_mount_options *args)
{
        dout("destroy_mount_options %p\n", args);
        if (!args)
                return;

        kfree(args->snapdir_name);
        kfree(args->mds_namespace);
        kfree(args->server_path);
        kfree(args->fscache_uniq);
        kfree(args->mon_addr);
        fscrypt_free_dummy_policy(&args->dummy_enc_policy);
        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;

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

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

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

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

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

/**
 * ceph_show_options - Show mount options in /proc/mounts
 * @m: seq_file to write to
 * @root: root of that (sub)tree
 */
static int ceph_show_options(struct seq_file *m, struct dentry *root)
{
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(root->d_sb);
        struct ceph_mount_options *fsopt = fsc->mount_options;
        size_t pos;
        int ret;

        /* a comma between MNT/MS and client options */
        seq_putc(m, ',');
        pos = m->count;

        ret = ceph_print_client_options(m, fsc->client, false);
        if (ret)
                return ret;

        /* retract our comma if no client options */
        if (m->count == pos)
                m->count--;

        if (fsopt->flags & CEPH_MOUNT_OPT_DIRSTAT)
                seq_puts(m, ",dirstat");
        if ((fsopt->flags & CEPH_MOUNT_OPT_RBYTES))
                seq_puts(m, ",rbytes");
        if (fsopt->flags & CEPH_MOUNT_OPT_NOASYNCREADDIR)
                seq_puts(m, ",noasyncreaddir");
        if ((fsopt->flags & CEPH_MOUNT_OPT_DCACHE) == 0)
                seq_puts(m, ",nodcache");
        if (fsopt->flags & CEPH_MOUNT_OPT_INO32)
                seq_puts(m, ",ino32");
        if (fsopt->flags & CEPH_MOUNT_OPT_FSCACHE) {
                seq_show_option(m, "fsc", fsopt->fscache_uniq);
        }
        if (fsopt->flags & CEPH_MOUNT_OPT_NOPOOLPERM)
                seq_puts(m, ",nopoolperm");
        if (fsopt->flags & CEPH_MOUNT_OPT_NOQUOTADF)
                seq_puts(m, ",noquotadf");

#ifdef CONFIG_CEPH_FS_POSIX_ACL
        if (root->d_sb->s_flags & SB_POSIXACL)
                seq_puts(m, ",acl");
        else
                seq_puts(m, ",noacl");
#endif

        if ((fsopt->flags & CEPH_MOUNT_OPT_NOCOPYFROM) == 0)
                seq_puts(m, ",copyfrom");

        /* dump mds_namespace when old device syntax is in use */
        if (fsopt->mds_namespace && !fsopt->new_dev_syntax)
                seq_show_option(m, "mds_namespace", fsopt->mds_namespace);

        if (fsopt->mon_addr)
                seq_printf(m, ",mon_addr=%s", fsopt->mon_addr);

        if (fsopt->flags & CEPH_MOUNT_OPT_CLEANRECOVER)
                seq_show_option(m, "recover_session", "clean");

        if (!(fsopt->flags & CEPH_MOUNT_OPT_ASYNC_DIROPS))
                seq_puts(m, ",wsync");
        if (fsopt->flags & CEPH_MOUNT_OPT_NOPAGECACHE)
                seq_puts(m, ",nopagecache");
        if (fsopt->flags & CEPH_MOUNT_OPT_SPARSEREAD)
                seq_puts(m, ",sparseread");

        fscrypt_show_test_dummy_encryption(m, ',', root->d_sb);

        if (fsopt->wsize != CEPH_MAX_WRITE_SIZE)
                seq_printf(m, ",wsize=%u", fsopt->wsize);
        if (fsopt->rsize != CEPH_MAX_READ_SIZE)
                seq_printf(m, ",rsize=%u", fsopt->rsize);
        if (fsopt->rasize != CEPH_RASIZE_DEFAULT)
                seq_printf(m, ",rasize=%u", fsopt->rasize);
        if (fsopt->congestion_kb != default_congestion_kb())
                seq_printf(m, ",write_congestion_kb=%u", fsopt->congestion_kb);
        if (fsopt->caps_max)
                seq_printf(m, ",caps_max=%d", fsopt->caps_max);
        if (fsopt->caps_wanted_delay_min != CEPH_CAPS_WANTED_DELAY_MIN_DEFAULT)
                seq_printf(m, ",caps_wanted_delay_min=%u",
                         fsopt->caps_wanted_delay_min);
        if (fsopt->caps_wanted_delay_max != CEPH_CAPS_WANTED_DELAY_MAX_DEFAULT)
                seq_printf(m, ",caps_wanted_delay_max=%u",
                           fsopt->caps_wanted_delay_max);
        if (fsopt->max_readdir != CEPH_MAX_READDIR_DEFAULT)
                seq_printf(m, ",readdir_max_entries=%u", fsopt->max_readdir);
        if (fsopt->max_readdir_bytes != CEPH_MAX_READDIR_BYTES_DEFAULT)
                seq_printf(m, ",readdir_max_bytes=%u", fsopt->max_readdir_bytes);
        if (strcmp(fsopt->snapdir_name, CEPH_SNAPDIRNAME_DEFAULT))
                seq_show_option(m, "snapdirname", 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_mdsmap(fsc->mdsc, msg);
                return 0;
        case CEPH_MSG_FS_MAP_USER:
                ceph_mdsc_handle_fsmap(fsc->mdsc, msg);
                return 0;
        default:
                return -1;
        }
}

/*
 * create a new fs client
 *
 * Success or not, this function consumes @fsopt and @opt.
 */
static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
                                        struct ceph_options *opt)
{
        struct ceph_fs_client *fsc;
        int err;

        fsc = kzalloc(sizeof(*fsc), GFP_KERNEL);
        if (!fsc) {
                err = -ENOMEM;
                goto fail;
        }

        fsc->client = ceph_create_client(opt, fsc);
        if (IS_ERR(fsc->client)) {
                err = PTR_ERR(fsc->client);
                goto fail;
        }
        opt = NULL; /* fsc->client now owns this */

        fsc->client->extra_mon_dispatch = extra_mon_dispatch;
        ceph_set_opt(fsc->client, ABORT_ON_FULL);

        if (!fsopt->mds_namespace) {
                ceph_monc_want_map(&fsc->client->monc, CEPH_SUB_MDSMAP,
                                   0, true);
        } else {
                ceph_monc_want_map(&fsc->client->monc, CEPH_SUB_FSMAP,
                                   0, false);
        }

        fsc->mount_options = fsopt;

        fsc->sb = NULL;
        fsc->mount_state = CEPH_MOUNT_MOUNTING;
        fsc->filp_gen = 1;
        fsc->have_copy_from2 = true;

        atomic_long_set(&fsc->writeback_count, 0);
        fsc->write_congested = false;

        err = -ENOMEM;
        /*
         * The number of concurrent works can be high but they don't need
         * to be processed in parallel, limit concurrency.
         */
        fsc->inode_wq = alloc_workqueue("ceph-inode", WQ_UNBOUND, 0);
        if (!fsc->inode_wq)
                goto fail_client;
        fsc->cap_wq = alloc_workqueue("ceph-cap", 0, 1);
        if (!fsc->cap_wq)
                goto fail_inode_wq;

        hash_init(fsc->async_unlink_conflict);
        spin_lock_init(&fsc->async_unlink_conflict_lock);

        spin_lock(&ceph_fsc_lock);
        list_add_tail(&fsc->metric_wakeup, &ceph_fsc_list);
        spin_unlock(&ceph_fsc_lock);

        return fsc;

fail_inode_wq:
        destroy_workqueue(fsc->inode_wq);
fail_client:
        ceph_destroy_client(fsc->client);
fail:
        kfree(fsc);
        if (opt)
                ceph_destroy_options(opt);
        destroy_mount_options(fsopt);
        return ERR_PTR(err);
}

static void flush_fs_workqueues(struct ceph_fs_client *fsc)
{
        flush_workqueue(fsc->inode_wq);
        flush_workqueue(fsc->cap_wq);
}

static void destroy_fs_client(struct ceph_fs_client *fsc)
{
        doutc(fsc->client, "%p\n", fsc);

        spin_lock(&ceph_fsc_lock);
        list_del(&fsc->metric_wakeup);
        spin_unlock(&ceph_fsc_lock);

        ceph_mdsc_destroy(fsc);
        destroy_workqueue(fsc->inode_wq);
        destroy_workqueue(fsc->cap_wq);

        destroy_mount_options(fsc->mount_options);

        ceph_destroy_client(fsc->client);

        kfree(fsc);
        dout("%s: %p done\n", __func__, fsc);
}

/*
 * caches
 */
struct kmem_cache *ceph_inode_cachep;
struct kmem_cache *ceph_cap_cachep;
struct kmem_cache *ceph_cap_snap_cachep;
struct kmem_cache *ceph_cap_flush_cachep;
struct kmem_cache *ceph_dentry_cachep;
struct kmem_cache *ceph_file_cachep;
struct kmem_cache *ceph_dir_file_cachep;
struct kmem_cache *ceph_mds_request_cachep;
mempool_t *ceph_wb_pagevec_pool;

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

static int __init init_caches(void)
{
        int error = -ENOMEM;

        ceph_inode_cachep = kmem_cache_create("ceph_inode_info",
                                      sizeof(struct ceph_inode_info),
                                      __alignof__(struct ceph_inode_info),
                                      SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT,
                                      ceph_inode_init_once);
        if (!ceph_inode_cachep)
                return -ENOMEM;

        ceph_cap_cachep = KMEM_CACHE(ceph_cap, 0);
        if (!ceph_cap_cachep)
                goto bad_cap;
        ceph_cap_snap_cachep = KMEM_CACHE(ceph_cap_snap, 0);
        if (!ceph_cap_snap_cachep)
                goto bad_cap_snap;
        ceph_cap_flush_cachep = KMEM_CACHE(ceph_cap_flush,
                                           SLAB_RECLAIM_ACCOUNT);
        if (!ceph_cap_flush_cachep)
                goto bad_cap_flush;

        ceph_dentry_cachep = KMEM_CACHE(ceph_dentry_info,
                                        SLAB_RECLAIM_ACCOUNT);
        if (!ceph_dentry_cachep)
                goto bad_dentry;

        ceph_file_cachep = KMEM_CACHE(ceph_file_info, 0);
        if (!ceph_file_cachep)
                goto bad_file;

        ceph_dir_file_cachep = KMEM_CACHE(ceph_dir_file_info, 0);
        if (!ceph_dir_file_cachep)
                goto bad_dir_file;

        ceph_mds_request_cachep = KMEM_CACHE(ceph_mds_request, 0);
        if (!ceph_mds_request_cachep)
                goto bad_mds_req;

        ceph_wb_pagevec_pool = mempool_create_kmalloc_pool(10,
            (CEPH_MAX_WRITE_SIZE >> PAGE_SHIFT) * sizeof(struct page *));
        if (!ceph_wb_pagevec_pool)
                goto bad_pagevec_pool;

        return 0;

bad_pagevec_pool:
        kmem_cache_destroy(ceph_mds_request_cachep);
bad_mds_req:
        kmem_cache_destroy(ceph_dir_file_cachep);
bad_dir_file:
        kmem_cache_destroy(ceph_file_cachep);
bad_file:
        kmem_cache_destroy(ceph_dentry_cachep);
bad_dentry:
        kmem_cache_destroy(ceph_cap_flush_cachep);
bad_cap_flush:
        kmem_cache_destroy(ceph_cap_snap_cachep);
bad_cap_snap:
        kmem_cache_destroy(ceph_cap_cachep);
bad_cap:
        kmem_cache_destroy(ceph_inode_cachep);
        return error;
}

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_cap_snap_cachep);
        kmem_cache_destroy(ceph_cap_flush_cachep);
        kmem_cache_destroy(ceph_dentry_cachep);
        kmem_cache_destroy(ceph_file_cachep);
        kmem_cache_destroy(ceph_dir_file_cachep);
        kmem_cache_destroy(ceph_mds_request_cachep);
        mempool_destroy(ceph_wb_pagevec_pool);
}

static void __ceph_umount_begin(struct ceph_fs_client *fsc)
{
        ceph_osdc_abort_requests(&fsc->client->osdc, -EIO);
        ceph_mdsc_force_umount(fsc->mdsc);
        fsc->filp_gen++; // invalidate open files
}

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

        doutc(fsc->client, "starting forced umount\n");
        if (!fsc)
                return;
        fsc->mount_state = CEPH_MOUNT_SHUTDOWN;
        __ceph_umount_begin(fsc);
}

static const struct super_operations ceph_super_ops = {
        .alloc_inode    = ceph_alloc_inode,
        .free_inode     = ceph_free_inode,
        .write_inode    = ceph_write_inode,
        .drop_inode     = generic_delete_inode,
        .evict_inode    = ceph_evict_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_client *cl = fsc->client;
        struct ceph_mds_client *mdsc = fsc->mdsc;
        struct ceph_mds_request *req = NULL;
        int err;
        struct dentry *root;

        /* open dir */
        doutc(cl, "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);
        if (!req->r_path1) {
                root = ERR_PTR(-ENOMEM);
                goto out;
        }

        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;
        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;
                doutc(cl, "success\n");
                root = d_make_root(inode);
                if (!root) {
                        root = ERR_PTR(-ENOMEM);
                        goto out;
                }
                doutc(cl, "success, root dentry is %p\n", root);
        } else {
                root = ERR_PTR(err);
        }
out:
        ceph_mdsc_put_request(req);
        return root;
}

#ifdef CONFIG_FS_ENCRYPTION
static int ceph_apply_test_dummy_encryption(struct super_block *sb,
                                            struct fs_context *fc,
                                            struct ceph_mount_options *fsopt)
{
        struct ceph_fs_client *fsc = sb->s_fs_info;

        if (!fscrypt_is_dummy_policy_set(&fsopt->dummy_enc_policy))
                return 0;

        /* No changing encryption context on remount. */
        if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE &&
            !fscrypt_is_dummy_policy_set(&fsc->fsc_dummy_enc_policy)) {
                if (fscrypt_dummy_policies_equal(&fsopt->dummy_enc_policy,
                                                 &fsc->fsc_dummy_enc_policy))
                        return 0;
                errorfc(fc, "Can't set test_dummy_encryption on remount");
                return -EINVAL;
        }

        /* Also make sure fsopt doesn't contain a conflicting value. */
        if (fscrypt_is_dummy_policy_set(&fsc->fsc_dummy_enc_policy)) {
                if (fscrypt_dummy_policies_equal(&fsopt->dummy_enc_policy,
                                                 &fsc->fsc_dummy_enc_policy))
                        return 0;
                errorfc(fc, "Conflicting test_dummy_encryption options");
                return -EINVAL;
        }

        fsc->fsc_dummy_enc_policy = fsopt->dummy_enc_policy;
        memset(&fsopt->dummy_enc_policy, 0, sizeof(fsopt->dummy_enc_policy));

        warnfc(fc, "test_dummy_encryption mode enabled");
        return 0;
}
#else
static int ceph_apply_test_dummy_encryption(struct super_block *sb,
                                            struct fs_context *fc,
                                            struct ceph_mount_options *fsopt)
{
        return 0;
}
#endif

/*
 * mount: join the ceph cluster, and open root directory.
 */
static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc,
                                      struct fs_context *fc)
{
        struct ceph_client *cl = fsc->client;
        int err;
        unsigned long started = jiffies;  /* note the start time */
        struct dentry *root;

        doutc(cl, "mount start %p\n", fsc);
        mutex_lock(&fsc->client->mount_mutex);

        if (!fsc->sb->s_root) {
                const char *path = fsc->mount_options->server_path ?
                                     fsc->mount_options->server_path + 1 : "";

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

                /* setup fscache */
                if (fsc->mount_options->flags & CEPH_MOUNT_OPT_FSCACHE) {
                        err = ceph_fscache_register_fs(fsc, fc);
                        if (err < 0)
                                goto out;
                }

                err = ceph_apply_test_dummy_encryption(fsc->sb, fc,
                                                       fsc->mount_options);
                if (err)
                        goto out;

                doutc(cl, "mount opening path '%s'\n", path);

                ceph_fs_debugfs_init(fsc);

                root = open_root_dentry(fsc, path, started);
                if (IS_ERR(root)) {
                        err = PTR_ERR(root);
                        goto out;
                }
                fsc->sb->s_root = dget(root);
        } else {
                root = dget(fsc->sb->s_root);
        }

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

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

static int ceph_set_super(struct super_block *s, struct fs_context *fc)
{
        struct ceph_fs_client *fsc = s->s_fs_info;
        struct ceph_client *cl = fsc->client;
        int ret;

        doutc(cl, "%p\n", s);

        s->s_maxbytes = MAX_LFS_FILESIZE;

        s->s_xattr = ceph_xattr_handlers;
        fsc->sb = s;
        fsc->max_file_size = 1ULL << 40; /* temp value until we get mdsmap */

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

        s->s_time_gran = 1;
        s->s_time_min = 0;
        s->s_time_max = U32_MAX;
        s->s_flags |= SB_NODIRATIME | SB_NOATIME;

        ceph_fscrypt_set_ops(s);

        ret = set_anon_super_fc(s, fc);
        if (ret != 0)
                fsc->sb = NULL;
        return ret;
}

/*
 * share superblock if same fs AND options
 */
static int ceph_compare_super(struct super_block *sb, struct fs_context *fc)
{
        struct ceph_fs_client *new = fc->s_fs_info;
        struct ceph_mount_options *fsopt = new->mount_options;
        struct ceph_options *opt = new->client->options;
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);
        struct ceph_client *cl = fsc->client;

        doutc(cl, "%p\n", sb);

        if (compare_mount_options(fsopt, opt, fsc)) {
                doutc(cl, "monitor(s)/mount options don't match\n");
                return 0;
        }
        if ((opt->flags & CEPH_OPT_FSID) &&
            ceph_fsid_compare(&opt->fsid, &fsc->client->fsid)) {
                doutc(cl, "fsid doesn't match\n");
                return 0;
        }
        if (fc->sb_flags != (sb->s_flags & ~SB_BORN)) {
                doutc(cl, "flags differ\n");
                return 0;
        }

        if (fsc->blocklisted && !ceph_test_mount_opt(fsc, CLEANRECOVER)) {
                doutc(cl, "client is blocklisted (and CLEANRECOVER is not set)\n");
                return 0;
        }

        if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {
                doutc(cl, "client has been forcibly unmounted\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_setup_bdi(struct super_block *sb, struct ceph_fs_client *fsc)
{
        int err;

        err = super_setup_bdi_name(sb, "ceph-%ld",
                                   atomic_long_inc_return(&bdi_seq));
        if (err)
                return err;

        /* set ra_pages based on rasize mount option? */
        sb->s_bdi->ra_pages = fsc->mount_options->rasize >> PAGE_SHIFT;

        /* set io_pages based on max osd read size */
        sb->s_bdi->io_pages = fsc->mount_options->rsize >> PAGE_SHIFT;

        return 0;
}

static int ceph_get_tree(struct fs_context *fc)
{
        struct ceph_parse_opts_ctx *pctx = fc->fs_private;
        struct ceph_mount_options *fsopt = pctx->opts;
        struct super_block *sb;
        struct ceph_fs_client *fsc;
        struct dentry *res;
        int (*compare_super)(struct super_block *, struct fs_context *) =
                ceph_compare_super;
        int err;

        dout("ceph_get_tree\n");

        if (!fc->source)
                return invalfc(fc, "No source");
        if (fsopt->new_dev_syntax && !fsopt->mon_addr)
                return invalfc(fc, "No monitor address");

        /* create client (which we may/may not use) */
        fsc = create_fs_client(pctx->opts, pctx->copts);
        pctx->opts = NULL;
        pctx->copts = NULL;
        if (IS_ERR(fsc)) {
                err = PTR_ERR(fsc);
                goto out_final;
        }

        err = ceph_mdsc_init(fsc);
        if (err < 0)
                goto out;

        if (ceph_test_opt(fsc->client, NOSHARE))
                compare_super = NULL;

        fc->s_fs_info = fsc;
        sb = sget_fc(fc, compare_super, ceph_set_super);
        fc->s_fs_info = NULL;
        if (IS_ERR(sb)) {
                err = PTR_ERR(sb);
                goto out;
        }

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

        res = ceph_real_mount(fsc, fc);
        if (IS_ERR(res)) {
                err = PTR_ERR(res);
                goto out_splat;
        }

        doutc(fsc->client, "root %p inode %p ino %llx.%llx\n", res,
                    d_inode(res), ceph_vinop(d_inode(res)));
        fc->root = fsc->sb->s_root;
        return 0;

out_splat:
        if (!ceph_mdsmap_is_cluster_available(fsc->mdsc->mdsmap)) {
                pr_info("No mds server is up or the cluster is laggy\n");
                err = -EHOSTUNREACH;
        }

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

out:
        destroy_fs_client(fsc);
out_final:
        dout("ceph_get_tree fail %d\n", err);
        return err;
}

static void ceph_free_fc(struct fs_context *fc)
{
        struct ceph_parse_opts_ctx *pctx = fc->fs_private;

        if (pctx) {
                destroy_mount_options(pctx->opts);
                ceph_destroy_options(pctx->copts);
                kfree(pctx);
        }
}

static int ceph_reconfigure_fc(struct fs_context *fc)
{
        int err;
        struct ceph_parse_opts_ctx *pctx = fc->fs_private;
        struct ceph_mount_options *fsopt = pctx->opts;
        struct super_block *sb = fc->root->d_sb;
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);

        err = ceph_apply_test_dummy_encryption(sb, fc, fsopt);
        if (err)
                return err;

        if (fsopt->flags & CEPH_MOUNT_OPT_ASYNC_DIROPS)
                ceph_set_mount_opt(fsc, ASYNC_DIROPS);
        else
                ceph_clear_mount_opt(fsc, ASYNC_DIROPS);

        if (fsopt->flags & CEPH_MOUNT_OPT_SPARSEREAD)
                ceph_set_mount_opt(fsc, SPARSEREAD);
        else
                ceph_clear_mount_opt(fsc, SPARSEREAD);

        if (strcmp_null(fsc->mount_options->mon_addr, fsopt->mon_addr)) {
                kfree(fsc->mount_options->mon_addr);
                fsc->mount_options->mon_addr = fsopt->mon_addr;
                fsopt->mon_addr = NULL;
                pr_notice_client(fsc->client,
                        "monitor addresses recorded, but not used for reconnection");
        }

        sync_filesystem(sb);
        return 0;
}

static const struct fs_context_operations ceph_context_ops = {
        .free           = ceph_free_fc,
        .parse_param    = ceph_parse_mount_param,
        .get_tree       = ceph_get_tree,
        .reconfigure    = ceph_reconfigure_fc,
};

/*
 * Set up the filesystem mount context.
 */
static int ceph_init_fs_context(struct fs_context *fc)
{
        struct ceph_parse_opts_ctx *pctx;
        struct ceph_mount_options *fsopt;

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

        pctx->copts = ceph_alloc_options();
        if (!pctx->copts)
                goto nomem;

        pctx->opts = kzalloc(sizeof(*pctx->opts), GFP_KERNEL);
        if (!pctx->opts)
                goto nomem;

        fsopt = pctx->opts;
        fsopt->flags = CEPH_MOUNT_OPT_DEFAULT;

        fsopt->wsize = CEPH_MAX_WRITE_SIZE;
        fsopt->rsize = CEPH_MAX_READ_SIZE;
        fsopt->rasize = CEPH_RASIZE_DEFAULT;
        fsopt->snapdir_name = kstrdup(CEPH_SNAPDIRNAME_DEFAULT, GFP_KERNEL);
        if (!fsopt->snapdir_name)
                goto nomem;

        fsopt->caps_wanted_delay_min = CEPH_CAPS_WANTED_DELAY_MIN_DEFAULT;
        fsopt->caps_wanted_delay_max = CEPH_CAPS_WANTED_DELAY_MAX_DEFAULT;
        fsopt->max_readdir = CEPH_MAX_READDIR_DEFAULT;
        fsopt->max_readdir_bytes = CEPH_MAX_READDIR_BYTES_DEFAULT;
        fsopt->congestion_kb = default_congestion_kb();

#ifdef CONFIG_CEPH_FS_POSIX_ACL
        fc->sb_flags |= SB_POSIXACL;
#endif

        fc->fs_private = pctx;
        fc->ops = &ceph_context_ops;
        return 0;

nomem:
        destroy_mount_options(pctx->opts);
        ceph_destroy_options(pctx->copts);
        kfree(pctx);
        return -ENOMEM;
}

/*
 * Return true if it successfully increases the blocker counter,
 * or false if the mdsc is in stopping and flushed state.
 */
static bool __inc_stopping_blocker(struct ceph_mds_client *mdsc)
{
        spin_lock(&mdsc->stopping_lock);
        if (mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHING) {
                spin_unlock(&mdsc->stopping_lock);
                return false;
        }
        atomic_inc(&mdsc->stopping_blockers);
        spin_unlock(&mdsc->stopping_lock);
        return true;
}

static void __dec_stopping_blocker(struct ceph_mds_client *mdsc)
{
        spin_lock(&mdsc->stopping_lock);
        if (!atomic_dec_return(&mdsc->stopping_blockers) &&
            mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHING)
                complete_all(&mdsc->stopping_waiter);
        spin_unlock(&mdsc->stopping_lock);
}

/* For metadata IO requests */
bool ceph_inc_mds_stopping_blocker(struct ceph_mds_client *mdsc,
                                   struct ceph_mds_session *session)
{
        mutex_lock(&session->s_mutex);
        inc_session_sequence(session);
        mutex_unlock(&session->s_mutex);

        return __inc_stopping_blocker(mdsc);
}

void ceph_dec_mds_stopping_blocker(struct ceph_mds_client *mdsc)
{
        __dec_stopping_blocker(mdsc);
}

/* For data IO requests */
bool ceph_inc_osd_stopping_blocker(struct ceph_mds_client *mdsc)
{
        return __inc_stopping_blocker(mdsc);
}

void ceph_dec_osd_stopping_blocker(struct ceph_mds_client *mdsc)
{
        __dec_stopping_blocker(mdsc);
}

static void ceph_kill_sb(struct super_block *s)
{
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(s);
        struct ceph_client *cl = fsc->client;
        struct ceph_mds_client *mdsc = fsc->mdsc;
        bool wait;

        doutc(cl, "%p\n", s);

        ceph_mdsc_pre_umount(mdsc);
        flush_fs_workqueues(fsc);

        /*
         * Though the kill_anon_super() will finally trigger the
         * sync_filesystem() anyway, we still need to do it here and
         * then bump the stage of shutdown. This will allow us to
         * drop any further message, which will increase the inodes'
         * i_count reference counters but makes no sense any more,
         * from MDSs.
         *
         * Without this when evicting the inodes it may fail in the
         * kill_anon_super(), which will trigger a warning when
         * destroying the fscrypt keyring and then possibly trigger
         * a further crash in ceph module when the iput() tries to
         * evict the inodes later.
         */
        sync_filesystem(s);

        spin_lock(&mdsc->stopping_lock);
        mdsc->stopping = CEPH_MDSC_STOPPING_FLUSHING;
        wait = !!atomic_read(&mdsc->stopping_blockers);
        spin_unlock(&mdsc->stopping_lock);

        if (wait && atomic_read(&mdsc->stopping_blockers)) {
                long timeleft = wait_for_completion_killable_timeout(
                                        &mdsc->stopping_waiter,
                                        fsc->client->options->mount_timeout);
                if (!timeleft) /* timed out */
                        pr_warn_client(cl, "umount timed out, %ld\n", timeleft);
                else if (timeleft < 0) /* killed */
                        pr_warn_client(cl, "umount was killed, %ld\n", timeleft);
        }

        mdsc->stopping = CEPH_MDSC_STOPPING_FLUSHED;
        kill_anon_super(s);

        fsc->client->extra_mon_dispatch = NULL;
        ceph_fs_debugfs_cleanup(fsc);

        ceph_fscache_unregister_fs(fsc);

        destroy_fs_client(fsc);
}

static struct file_system_type ceph_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "ceph",
        .init_fs_context = ceph_init_fs_context,
        .kill_sb        = ceph_kill_sb,
        .fs_flags       = FS_RENAME_DOES_D_MOVE | FS_ALLOW_IDMAP,
};
MODULE_ALIAS_FS("ceph");

int ceph_force_reconnect(struct super_block *sb)
{
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);
        int err = 0;

        fsc->mount_state = CEPH_MOUNT_RECOVER;
        __ceph_umount_begin(fsc);

        /* Make sure all page caches get invalidated.
         * see remove_session_caps_cb() */
        flush_workqueue(fsc->inode_wq);

        /* In case that we were blocklisted. This also reset
         * all mon/osd connections */
        ceph_reset_client_addr(fsc->client);

        ceph_osdc_clear_abort_err(&fsc->client->osdc);

        fsc->blocklisted = false;
        fsc->mount_state = CEPH_MOUNT_MOUNTED;

        if (sb->s_root) {
                err = __ceph_do_getattr(d_inode(sb->s_root), NULL,
                                        CEPH_STAT_CAP_INODE, true);
        }
        return err;
}

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

        ceph_flock_init();
        ret = register_filesystem(&ceph_fs_type);
        if (ret)
                goto out_caches;

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

        return 0;

out_caches:
        destroy_caches();
out:
        return ret;
}

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

static int param_set_metrics(const char *val, const struct kernel_param *kp)
{
        struct ceph_fs_client *fsc;
        int ret;

        ret = param_set_bool(val, kp);
        if (ret) {
                pr_err("Failed to parse sending metrics switch value '%s'\n",
                       val);
                return ret;
        } else if (!disable_send_metrics) {
                // wake up all the mds clients
                spin_lock(&ceph_fsc_lock);
                list_for_each_entry(fsc, &ceph_fsc_list, metric_wakeup) {
                        metric_schedule_delayed(&fsc->mdsc->metric);
                }
                spin_unlock(&ceph_fsc_lock);
        }

        return 0;
}

static const struct kernel_param_ops param_ops_metrics = {
        .set = param_set_metrics,
        .get = param_get_bool,
};

bool disable_send_metrics = false;
module_param_cb(disable_send_metrics, &param_ops_metrics, &disable_send_metrics, 0644);
MODULE_PARM_DESC(disable_send_metrics, "Enable sending perf metrics to ceph cluster (default: on)");

/* for both v1 and v2 syntax */
static bool mount_support = true;
static const struct kernel_param_ops param_ops_mount_syntax = {
        .get = param_get_bool,
};
module_param_cb(mount_syntax_v1, &param_ops_mount_syntax, &mount_support, 0444);
module_param_cb(mount_syntax_v2, &param_ops_mount_syntax, &mount_support, 0444);

bool enable_unsafe_idmap = false;
module_param(enable_unsafe_idmap, bool, 0644);
MODULE_PARM_DESC(enable_unsafe_idmap,
                 "Allow to use idmapped mounts with MDS without CEPHFS_FEATURE_HAS_OWNER_UIDGID");

module_init(init_ceph);
module_exit(exit_ceph);

MODULE_AUTHOR("Sage Weil <sage@newdream.net>");
MODULE_AUTHOR("Yehuda Sadeh <yehuda@hq.newdream.net>");
MODULE_AUTHOR("Patience Warnick <patience@newdream.net>");
MODULE_DESCRIPTION("Ceph filesystem for Linux");
MODULE_LICENSE("GPL");