#include <linux/ceph/ceph_debug.h>

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/namei.h>
#include <linux/writeback.h>
#include <linux/vmalloc.h>
#include <linux/pagevec.h>

#include "super.h"
#include "mds_client.h"
#include <linux/ceph/decode.h>

/*
 * Ceph inode operations
 *
 * Implement basic inode helpers (get, alloc) and inode ops (getattr,
 * setattr, etc.), xattr helpers, and helpers for assimilating
 * metadata returned by the MDS into our cache.
 *
 * Also define helpers for doing asynchronous writeback, invalidation,
 * and truncation for the benefit of those who can't afford to block
 * (typically because they are in the message handler path).
 */

static const struct inode_operations ceph_symlink_iops;

static void ceph_invalidate_work(struct work_struct *work);
static void ceph_writeback_work(struct work_struct *work);
static void ceph_vmtruncate_work(struct work_struct *work);

/*
 * find or create an inode, given the ceph ino number
 */
struct inode *ceph_get_inode(struct super_block *sb, struct ceph_vino vino)
{
        struct inode *inode;
        ino_t t = ceph_vino_to_ino(vino);

        inode = iget5_locked(sb, t, ceph_ino_compare, ceph_set_ino_cb, &vino);
        if (inode == NULL)
                return ERR_PTR(-ENOMEM);
        if (inode->i_state & I_NEW) {
                dout("get_inode created new inode %p %llx.%llx ino %llx\n",
                     inode, ceph_vinop(inode), (u64)inode->i_ino);
                unlock_new_inode(inode);
        }

        dout("get_inode on %lu=%llx.%llx got %p\n", inode->i_ino, vino.ino,
             vino.snap, inode);
        return inode;
}

/*
 * get/constuct snapdir inode for a given directory
 */
struct inode *ceph_get_snapdir(struct inode *parent)
{
        struct ceph_vino vino = {
                .ino = ceph_ino(parent),
                .snap = CEPH_SNAPDIR,
        };
        struct inode *inode = ceph_get_inode(parent->i_sb, vino);
        struct ceph_inode_info *ci = ceph_inode(inode);

        BUG_ON(!S_ISDIR(parent->i_mode));
        if (IS_ERR(inode))
                return inode;
        inode->i_mode = parent->i_mode;
        inode->i_uid = parent->i_uid;
        inode->i_gid = parent->i_gid;
        inode->i_op = &ceph_dir_iops;
        inode->i_fop = &ceph_dir_fops;
        ci->i_snap_caps = CEPH_CAP_PIN; /* so we can open */
        ci->i_rbytes = 0;
        return inode;
}

const struct inode_operations ceph_file_iops = {
        .permission = ceph_permission,
        .setattr = ceph_setattr,
        .getattr = ceph_getattr,
        .setxattr = ceph_setxattr,
        .getxattr = ceph_getxattr,
        .listxattr = ceph_listxattr,
        .removexattr = ceph_removexattr,
};


/*
 * We use a 'frag tree' to keep track of the MDS's directory fragments
 * for a given inode (usually there is just a single fragment).  We
 * need to know when a child frag is delegated to a new MDS, or when
 * it is flagged as replicated, so we can direct our requests
 * accordingly.
 */

/*
 * find/create a frag in the tree
 */
static struct ceph_inode_frag *__get_or_create_frag(struct ceph_inode_info *ci,
                                                    u32 f)
{
        struct rb_node **p;
        struct rb_node *parent = NULL;
        struct ceph_inode_frag *frag;
        int c;

        p = &ci->i_fragtree.rb_node;
        while (*p) {
                parent = *p;
                frag = rb_entry(parent, struct ceph_inode_frag, node);
                c = ceph_frag_compare(f, frag->frag);
                if (c < 0)
                        p = &(*p)->rb_left;
                else if (c > 0)
                        p = &(*p)->rb_right;
                else
                        return frag;
        }

        frag = kmalloc(sizeof(*frag), GFP_NOFS);
        if (!frag) {
                pr_err("__get_or_create_frag ENOMEM on %p %llx.%llx "
                       "frag %x\n", &ci->vfs_inode,
                       ceph_vinop(&ci->vfs_inode), f);
                return ERR_PTR(-ENOMEM);
        }
        frag->frag = f;
        frag->split_by = 0;
        frag->mds = -1;
        frag->ndist = 0;

        rb_link_node(&frag->node, parent, p);
        rb_insert_color(&frag->node, &ci->i_fragtree);

        dout("get_or_create_frag added %llx.%llx frag %x\n",
             ceph_vinop(&ci->vfs_inode), f);
        return frag;
}

/*
 * find a specific frag @f
 */
struct ceph_inode_frag *__ceph_find_frag(struct ceph_inode_info *ci, u32 f)
{
        struct rb_node *n = ci->i_fragtree.rb_node;

        while (n) {
                struct ceph_inode_frag *frag =
                        rb_entry(n, struct ceph_inode_frag, node);
                int c = ceph_frag_compare(f, frag->frag);
                if (c < 0)
                        n = n->rb_left;
                else if (c > 0)
                        n = n->rb_right;
                else
                        return frag;
        }
        return NULL;
}

/*
 * Choose frag containing the given value @v.  If @pfrag is
 * specified, copy the frag delegation info to the caller if
 * it is present.
 */
u32 ceph_choose_frag(struct ceph_inode_info *ci, u32 v,
                     struct ceph_inode_frag *pfrag,
                     int *found)
{
        u32 t = ceph_frag_make(0, 0);
        struct ceph_inode_frag *frag;
        unsigned nway, i;
        u32 n;

        if (found)
                *found = 0;

        mutex_lock(&ci->i_fragtree_mutex);
        while (1) {
                WARN_ON(!ceph_frag_contains_value(t, v));
                frag = __ceph_find_frag(ci, t);
                if (!frag)
                        break; /* t is a leaf */
                if (frag->split_by == 0) {
                        if (pfrag)
                                memcpy(pfrag, frag, sizeof(*pfrag));
                        if (found)
                                *found = 1;
                        break;
                }

                /* choose child */
                nway = 1 << frag->split_by;
                dout("choose_frag(%x) %x splits by %d (%d ways)\n", v, t,
                     frag->split_by, nway);
                for (i = 0; i < nway; i++) {
                        n = ceph_frag_make_child(t, frag->split_by, i);
                        if (ceph_frag_contains_value(n, v)) {
                                t = n;
                                break;
                        }
                }
                BUG_ON(i == nway);
        }
        dout("choose_frag(%x) = %x\n", v, t);

        mutex_unlock(&ci->i_fragtree_mutex);
        return t;
}

/*
 * Process dirfrag (delegation) info from the mds.  Include leaf
 * fragment in tree ONLY if ndist > 0.  Otherwise, only
 * branches/splits are included in i_fragtree)
 */
static int ceph_fill_dirfrag(struct inode *inode,
                             struct ceph_mds_reply_dirfrag *dirinfo)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_inode_frag *frag;
        u32 id = le32_to_cpu(dirinfo->frag);
        int mds = le32_to_cpu(dirinfo->auth);
        int ndist = le32_to_cpu(dirinfo->ndist);
        int i;
        int err = 0;

        mutex_lock(&ci->i_fragtree_mutex);
        if (ndist == 0) {
                /* no delegation info needed. */
                frag = __ceph_find_frag(ci, id);
                if (!frag)
                        goto out;
                if (frag->split_by == 0) {
                        /* tree leaf, remove */
                        dout("fill_dirfrag removed %llx.%llx frag %x"
                             " (no ref)\n", ceph_vinop(inode), id);
                        rb_erase(&frag->node, &ci->i_fragtree);
                        kfree(frag);
                } else {
                        /* tree branch, keep and clear */
                        dout("fill_dirfrag cleared %llx.%llx frag %x"
                             " referral\n", ceph_vinop(inode), id);
                        frag->mds = -1;
                        frag->ndist = 0;
                }
                goto out;
        }


        /* find/add this frag to store mds delegation info */
        frag = __get_or_create_frag(ci, id);
        if (IS_ERR(frag)) {
                /* this is not the end of the world; we can continue
                   with bad/inaccurate delegation info */
                pr_err("fill_dirfrag ENOMEM on mds ref %llx.%llx fg %x\n",
                       ceph_vinop(inode), le32_to_cpu(dirinfo->frag));
                err = -ENOMEM;
                goto out;
        }

        frag->mds = mds;
        frag->ndist = min_t(u32, ndist, CEPH_MAX_DIRFRAG_REP);
        for (i = 0; i < frag->ndist; i++)
                frag->dist[i] = le32_to_cpu(dirinfo->dist[i]);
        dout("fill_dirfrag %llx.%llx frag %x ndist=%d\n",
             ceph_vinop(inode), frag->frag, frag->ndist);

out:
        mutex_unlock(&ci->i_fragtree_mutex);
        return err;
}


/*
 * initialize a newly allocated inode.
 */
struct inode *ceph_alloc_inode(struct super_block *sb)
{
        struct ceph_inode_info *ci;
        int i;

        ci = kmem_cache_alloc(ceph_inode_cachep, GFP_NOFS);
        if (!ci)
                return NULL;

        dout("alloc_inode %p\n", &ci->vfs_inode);

        ci->i_version = 0;
        ci->i_time_warp_seq = 0;
        ci->i_ceph_flags = 0;
        ci->i_release_count = 0;
        ci->i_symlink = NULL;

        memset(&ci->i_dir_layout, 0, sizeof(ci->i_dir_layout));

        ci->i_fragtree = RB_ROOT;
        mutex_init(&ci->i_fragtree_mutex);

        ci->i_xattrs.blob = NULL;
        ci->i_xattrs.prealloc_blob = NULL;
        ci->i_xattrs.dirty = false;
        ci->i_xattrs.index = RB_ROOT;
        ci->i_xattrs.count = 0;
        ci->i_xattrs.names_size = 0;
        ci->i_xattrs.vals_size = 0;
        ci->i_xattrs.version = 0;
        ci->i_xattrs.index_version = 0;

        ci->i_caps = RB_ROOT;
        ci->i_auth_cap = NULL;
        ci->i_dirty_caps = 0;
        ci->i_flushing_caps = 0;
        INIT_LIST_HEAD(&ci->i_dirty_item);
        INIT_LIST_HEAD(&ci->i_flushing_item);
        ci->i_cap_flush_seq = 0;
        ci->i_cap_flush_last_tid = 0;
        memset(&ci->i_cap_flush_tid, 0, sizeof(ci->i_cap_flush_tid));
        init_waitqueue_head(&ci->i_cap_wq);
        ci->i_hold_caps_min = 0;
        ci->i_hold_caps_max = 0;
        INIT_LIST_HEAD(&ci->i_cap_delay_list);
        ci->i_cap_exporting_mds = 0;
        ci->i_cap_exporting_mseq = 0;
        ci->i_cap_exporting_issued = 0;
        INIT_LIST_HEAD(&ci->i_cap_snaps);
        ci->i_head_snapc = NULL;
        ci->i_snap_caps = 0;

        for (i = 0; i < CEPH_FILE_MODE_NUM; i++)
                ci->i_nr_by_mode[i] = 0;

        ci->i_truncate_seq = 0;
        ci->i_truncate_size = 0;
        ci->i_truncate_pending = 0;

        ci->i_max_size = 0;
        ci->i_reported_size = 0;
        ci->i_wanted_max_size = 0;
        ci->i_requested_max_size = 0;

        ci->i_pin_ref = 0;
        ci->i_rd_ref = 0;
        ci->i_rdcache_ref = 0;
        ci->i_wr_ref = 0;
        ci->i_wrbuffer_ref = 0;
        ci->i_wrbuffer_ref_head = 0;
        ci->i_shared_gen = 0;
        ci->i_rdcache_gen = 0;
        ci->i_rdcache_revoking = 0;

        INIT_LIST_HEAD(&ci->i_unsafe_writes);
        INIT_LIST_HEAD(&ci->i_unsafe_dirops);
        spin_lock_init(&ci->i_unsafe_lock);

        ci->i_snap_realm = NULL;
        INIT_LIST_HEAD(&ci->i_snap_realm_item);
        INIT_LIST_HEAD(&ci->i_snap_flush_item);

        INIT_WORK(&ci->i_wb_work, ceph_writeback_work);
        INIT_WORK(&ci->i_pg_inv_work, ceph_invalidate_work);

        INIT_WORK(&ci->i_vmtruncate_work, ceph_vmtruncate_work);

        return &ci->vfs_inode;
}

static void ceph_i_callback(struct rcu_head *head)
{
        struct inode *inode = container_of(head, struct inode, i_rcu);
        struct ceph_inode_info *ci = ceph_inode(inode);

        INIT_LIST_HEAD(&inode->i_dentry);
        kmem_cache_free(ceph_inode_cachep, ci);
}

void ceph_destroy_inode(struct inode *inode)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct ceph_inode_frag *frag;
        struct rb_node *n;

        dout("destroy_inode %p ino %llx.%llx\n", inode, ceph_vinop(inode));

        ceph_queue_caps_release(inode);

        /*
         * we may still have a snap_realm reference if there are stray
         * caps in i_cap_exporting_issued or i_snap_caps.
         */
        if (ci->i_snap_realm) {
                struct ceph_mds_client *mdsc =
                        ceph_sb_to_client(ci->vfs_inode.i_sb)->mdsc;
                struct ceph_snap_realm *realm = ci->i_snap_realm;

                dout(" dropping residual ref to snap realm %p\n", realm);
                spin_lock(&realm->inodes_with_caps_lock);
                list_del_init(&ci->i_snap_realm_item);
                spin_unlock(&realm->inodes_with_caps_lock);
                ceph_put_snap_realm(mdsc, realm);
        }

        kfree(ci->i_symlink);
        while ((n = rb_first(&ci->i_fragtree)) != NULL) {
                frag = rb_entry(n, struct ceph_inode_frag, node);
                rb_erase(n, &ci->i_fragtree);
                kfree(frag);
        }

        __ceph_destroy_xattrs(ci);
        if (ci->i_xattrs.blob)
                ceph_buffer_put(ci->i_xattrs.blob);
        if (ci->i_xattrs.prealloc_blob)
                ceph_buffer_put(ci->i_xattrs.prealloc_blob);

        call_rcu(&inode->i_rcu, ceph_i_callback);
}


/*
 * Helpers to fill in size, ctime, mtime, and atime.  We have to be
 * careful because either the client or MDS may have more up to date
 * info, depending on which capabilities are held, and whether
 * time_warp_seq or truncate_seq have increased.  (Ordinarily, mtime
 * and size are monotonically increasing, except when utimes() or
 * truncate() increments the corresponding _seq values.)
 */
int ceph_fill_file_size(struct inode *inode, int issued,
                        u32 truncate_seq, u64 truncate_size, u64 size)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        int queue_trunc = 0;

        if (ceph_seq_cmp(truncate_seq, ci->i_truncate_seq) > 0 ||
            (truncate_seq == ci->i_truncate_seq && size > inode->i_size)) {
                dout("size %lld -> %llu\n", inode->i_size, size);
                inode->i_size = size;
                inode->i_blocks = (size + (1<<9) - 1) >> 9;
                ci->i_reported_size = size;
                if (truncate_seq != ci->i_truncate_seq) {
                        dout("truncate_seq %u -> %u\n",
                             ci->i_truncate_seq, truncate_seq);
                        ci->i_truncate_seq = truncate_seq;
                        /*
                         * If we hold relevant caps, or in the case where we're
                         * not the only client referencing this file and we
                         * don't hold those caps, then we need to check whether
                         * the file is either opened or mmaped
                         */
                        if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_RD|
                                       CEPH_CAP_FILE_WR|CEPH_CAP_FILE_BUFFER|
                                       CEPH_CAP_FILE_EXCL|
                                       CEPH_CAP_FILE_LAZYIO)) ||
                            mapping_mapped(inode->i_mapping) ||
                            __ceph_caps_file_wanted(ci)) {
                                ci->i_truncate_pending++;
                                queue_trunc = 1;
                        }
                }
        }
        if (ceph_seq_cmp(truncate_seq, ci->i_truncate_seq) >= 0 &&
            ci->i_truncate_size != truncate_size) {
                dout("truncate_size %lld -> %llu\n", ci->i_truncate_size,
                     truncate_size);
                ci->i_truncate_size = truncate_size;
        }
        return queue_trunc;
}

void ceph_fill_file_time(struct inode *inode, int issued,
                         u64 time_warp_seq, struct timespec *ctime,
                         struct timespec *mtime, struct timespec *atime)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        int warn = 0;

        if (issued & (CEPH_CAP_FILE_EXCL|
                      CEPH_CAP_FILE_WR|
                      CEPH_CAP_FILE_BUFFER|
                      CEPH_CAP_AUTH_EXCL|
                      CEPH_CAP_XATTR_EXCL)) {
                if (timespec_compare(ctime, &inode->i_ctime) > 0) {
                        dout("ctime %ld.%09ld -> %ld.%09ld inc w/ cap\n",
                             inode->i_ctime.tv_sec, inode->i_ctime.tv_nsec,
                             ctime->tv_sec, ctime->tv_nsec);
                        inode->i_ctime = *ctime;
                }
                if (ceph_seq_cmp(time_warp_seq, ci->i_time_warp_seq) > 0) {
                        /* the MDS did a utimes() */
                        dout("mtime %ld.%09ld -> %ld.%09ld "
                             "tw %d -> %d\n",
                             inode->i_mtime.tv_sec, inode->i_mtime.tv_nsec,
                             mtime->tv_sec, mtime->tv_nsec,
                             ci->i_time_warp_seq, (int)time_warp_seq);

                        inode->i_mtime = *mtime;
                        inode->i_atime = *atime;
                        ci->i_time_warp_seq = time_warp_seq;
                } else if (time_warp_seq == ci->i_time_warp_seq) {
                        /* nobody did utimes(); take the max */
                        if (timespec_compare(mtime, &inode->i_mtime) > 0) {
                                dout("mtime %ld.%09ld -> %ld.%09ld inc\n",
                                     inode->i_mtime.tv_sec,
                                     inode->i_mtime.tv_nsec,
                                     mtime->tv_sec, mtime->tv_nsec);
                                inode->i_mtime = *mtime;
                        }
                        if (timespec_compare(atime, &inode->i_atime) > 0) {
                                dout("atime %ld.%09ld -> %ld.%09ld inc\n",
                                     inode->i_atime.tv_sec,
                                     inode->i_atime.tv_nsec,
                                     atime->tv_sec, atime->tv_nsec);
                                inode->i_atime = *atime;
                        }
                } else if (issued & CEPH_CAP_FILE_EXCL) {
                        /* we did a utimes(); ignore mds values */
                } else {
                        warn = 1;
                }
        } else {
                /* we have no write|excl caps; whatever the MDS says is true */
                if (ceph_seq_cmp(time_warp_seq, ci->i_time_warp_seq) >= 0) {
                        inode->i_ctime = *ctime;
                        inode->i_mtime = *mtime;
                        inode->i_atime = *atime;
                        ci->i_time_warp_seq = time_warp_seq;
                } else {
                        warn = 1;
                }
        }
        if (warn) /* time_warp_seq shouldn't go backwards */
                dout("%p mds time_warp_seq %llu < %u\n",
                     inode, time_warp_seq, ci->i_time_warp_seq);
}

/*
 * Populate an inode based on info from mds.  May be called on new or
 * existing inodes.
 */
static int fill_inode(struct inode *inode,
                      struct ceph_mds_reply_info_in *iinfo,
                      struct ceph_mds_reply_dirfrag *dirinfo,
                      struct ceph_mds_session *session,
                      unsigned long ttl_from, int cap_fmode,
                      struct ceph_cap_reservation *caps_reservation)
{
        struct ceph_mds_reply_inode *info = iinfo->in;
        struct ceph_inode_info *ci = ceph_inode(inode);
        int i;
        int issued, implemented;
        struct timespec mtime, atime, ctime;
        u32 nsplits;
        struct ceph_buffer *xattr_blob = NULL;
        int err = 0;
        int queue_trunc = 0;

        dout("fill_inode %p ino %llx.%llx v %llu had %llu\n",
             inode, ceph_vinop(inode), le64_to_cpu(info->version),
             ci->i_version);

        /*
         * prealloc xattr data, if it looks like we'll need it.  only
         * if len > 4 (meaning there are actually xattrs; the first 4
         * bytes are the xattr count).
         */
        if (iinfo->xattr_len > 4) {
                xattr_blob = ceph_buffer_new(iinfo->xattr_len, GFP_NOFS);
                if (!xattr_blob)
                        pr_err("fill_inode ENOMEM xattr blob %d bytes\n",
                               iinfo->xattr_len);
        }

        spin_lock(&inode->i_lock);

        /*
         * provided version will be odd if inode value is projected,
         * even if stable.  skip the update if we have newer stable
         * info (ours>=theirs, e.g. due to racing mds replies), unless
         * we are getting projected (unstable) info (in which case the
         * version is odd, and we want ours>theirs).
         *   us   them
         *   2    2     skip
         *   3    2     skip
         *   3    3     update
         */
        if (le64_to_cpu(info->version) > 0 &&
            (ci->i_version & ~1) >= le64_to_cpu(info->version))
                goto no_change;

        issued = __ceph_caps_issued(ci, &implemented);
        issued |= implemented | __ceph_caps_dirty(ci);

        /* update inode */
        ci->i_version = le64_to_cpu(info->version);
        inode->i_version++;
        inode->i_rdev = le32_to_cpu(info->rdev);

        if ((issued & CEPH_CAP_AUTH_EXCL) == 0) {
                inode->i_mode = le32_to_cpu(info->mode);
                inode->i_uid = le32_to_cpu(info->uid);
                inode->i_gid = le32_to_cpu(info->gid);
                dout("%p mode 0%o uid.gid %d.%d\n", inode, inode->i_mode,
                     inode->i_uid, inode->i_gid);
        }

        if ((issued & CEPH_CAP_LINK_EXCL) == 0)
                inode->i_nlink = le32_to_cpu(info->nlink);

        /* be careful with mtime, atime, size */
        ceph_decode_timespec(&atime, &info->atime);
        ceph_decode_timespec(&mtime, &info->mtime);
        ceph_decode_timespec(&ctime, &info->ctime);
        queue_trunc = ceph_fill_file_size(inode, issued,
                                          le32_to_cpu(info->truncate_seq),
                                          le64_to_cpu(info->truncate_size),
                                          le64_to_cpu(info->size));
        ceph_fill_file_time(inode, issued,
                            le32_to_cpu(info->time_warp_seq),
                            &ctime, &mtime, &atime);

        /* only update max_size on auth cap */
        if ((info->cap.flags & CEPH_CAP_FLAG_AUTH) &&
            ci->i_max_size != le64_to_cpu(info->max_size)) {
                dout("max_size %lld -> %llu\n", ci->i_max_size,
                     le64_to_cpu(info->max_size));
                ci->i_max_size = le64_to_cpu(info->max_size);
        }

        ci->i_layout = info->layout;
        inode->i_blkbits = fls(le32_to_cpu(info->layout.fl_stripe_unit)) - 1;

        /* xattrs */
        /* note that if i_xattrs.len <= 4, i_xattrs.data will still be NULL. */
        if ((issued & CEPH_CAP_XATTR_EXCL) == 0 &&
            le64_to_cpu(info->xattr_version) > ci->i_xattrs.version) {
                if (ci->i_xattrs.blob)
                        ceph_buffer_put(ci->i_xattrs.blob);
                ci->i_xattrs.blob = xattr_blob;
                if (xattr_blob)
                        memcpy(ci->i_xattrs.blob->vec.iov_base,
                               iinfo->xattr_data, iinfo->xattr_len);
                ci->i_xattrs.version = le64_to_cpu(info->xattr_version);
                xattr_blob = NULL;
        }

        inode->i_mapping->a_ops = &ceph_aops;
        inode->i_mapping->backing_dev_info =
                &ceph_sb_to_client(inode->i_sb)->backing_dev_info;

        switch (inode->i_mode & S_IFMT) {
        case S_IFIFO:
        case S_IFBLK:
        case S_IFCHR:
        case S_IFSOCK:
                init_special_inode(inode, inode->i_mode, inode->i_rdev);
                inode->i_op = &ceph_file_iops;
                break;
        case S_IFREG:
                inode->i_op = &ceph_file_iops;
                inode->i_fop = &ceph_file_fops;
                break;
        case S_IFLNK:
                inode->i_op = &ceph_symlink_iops;
                if (!ci->i_symlink) {
                        int symlen = iinfo->symlink_len;
                        char *sym;

                        BUG_ON(symlen != inode->i_size);
                        spin_unlock(&inode->i_lock);

                        err = -ENOMEM;
                        sym = kmalloc(symlen+1, GFP_NOFS);
                        if (!sym)
                                goto out;
                        memcpy(sym, iinfo->symlink, symlen);
                        sym[symlen] = 0;

                        spin_lock(&inode->i_lock);
                        if (!ci->i_symlink)
                                ci->i_symlink = sym;
                        else
                                kfree(sym); /* lost a race */
                }
                break;
        case S_IFDIR:
                inode->i_op = &ceph_dir_iops;
                inode->i_fop = &ceph_dir_fops;

                ci->i_dir_layout = iinfo->dir_layout;

                ci->i_files = le64_to_cpu(info->files);
                ci->i_subdirs = le64_to_cpu(info->subdirs);
                ci->i_rbytes = le64_to_cpu(info->rbytes);
                ci->i_rfiles = le64_to_cpu(info->rfiles);
                ci->i_rsubdirs = le64_to_cpu(info->rsubdirs);
                ceph_decode_timespec(&ci->i_rctime, &info->rctime);

                /* set dir completion flag? */
                if (ci->i_files == 0 && ci->i_subdirs == 0 &&
                    ceph_snap(inode) == CEPH_NOSNAP &&
                    (le32_to_cpu(info->cap.caps) & CEPH_CAP_FILE_SHARED) &&
                    (issued & CEPH_CAP_FILE_EXCL) == 0 &&
                    (ci->i_ceph_flags & CEPH_I_COMPLETE) == 0) {
                        dout(" marking %p complete (empty)\n", inode);
                        /* ci->i_ceph_flags |= CEPH_I_COMPLETE; */
                        ci->i_max_offset = 2;
                }
                break;
        default:
                pr_err("fill_inode %llx.%llx BAD mode 0%o\n",
                       ceph_vinop(inode), inode->i_mode);
        }

no_change:
        spin_unlock(&inode->i_lock);

        /* queue truncate if we saw i_size decrease */
        if (queue_trunc)
                ceph_queue_vmtruncate(inode);

        /* populate frag tree */
        /* FIXME: move me up, if/when version reflects fragtree changes */
        nsplits = le32_to_cpu(info->fragtree.nsplits);
        mutex_lock(&ci->i_fragtree_mutex);
        for (i = 0; i < nsplits; i++) {
                u32 id = le32_to_cpu(info->fragtree.splits[i].frag);
                struct ceph_inode_frag *frag = __get_or_create_frag(ci, id);

                if (IS_ERR(frag))
                        continue;
                frag->split_by = le32_to_cpu(info->fragtree.splits[i].by);
                dout(" frag %x split by %d\n", frag->frag, frag->split_by);
        }
        mutex_unlock(&ci->i_fragtree_mutex);

        /* were we issued a capability? */
        if (info->cap.caps) {
                if (ceph_snap(inode) == CEPH_NOSNAP) {
                        ceph_add_cap(inode, session,
                                     le64_to_cpu(info->cap.cap_id),
                                     cap_fmode,
                                     le32_to_cpu(info->cap.caps),
                                     le32_to_cpu(info->cap.wanted),
                                     le32_to_cpu(info->cap.seq),
                                     le32_to_cpu(info->cap.mseq),
                                     le64_to_cpu(info->cap.realm),
                                     info->cap.flags,
                                     caps_reservation);
                } else {
                        spin_lock(&inode->i_lock);
                        dout(" %p got snap_caps %s\n", inode,
                             ceph_cap_string(le32_to_cpu(info->cap.caps)));
                        ci->i_snap_caps |= le32_to_cpu(info->cap.caps);
                        if (cap_fmode >= 0)
                                __ceph_get_fmode(ci, cap_fmode);
                        spin_unlock(&inode->i_lock);
                }
        } else if (cap_fmode >= 0) {
                pr_warning("mds issued no caps on %llx.%llx\n",
                           ceph_vinop(inode));
                __ceph_get_fmode(ci, cap_fmode);
        }

        /* update delegation info? */
        if (dirinfo)
                ceph_fill_dirfrag(inode, dirinfo);

        err = 0;

out:
        if (xattr_blob)
                ceph_buffer_put(xattr_blob);
        return err;
}

/*
 * caller should hold session s_mutex.
 */
static void update_dentry_lease(struct dentry *dentry,
                                struct ceph_mds_reply_lease *lease,
                                struct ceph_mds_session *session,
                                unsigned long from_time)
{
        struct ceph_dentry_info *di = ceph_dentry(dentry);
        long unsigned duration = le32_to_cpu(lease->duration_ms);
        long unsigned ttl = from_time + (duration * HZ) / 1000;
        long unsigned half_ttl = from_time + (duration * HZ / 2) / 1000;
        struct inode *dir;

        /* only track leases on regular dentries */
        if (dentry->d_op != &ceph_dentry_ops)
                return;

        spin_lock(&dentry->d_lock);
        dout("update_dentry_lease %p mask %d duration %lu ms ttl %lu\n",
             dentry, le16_to_cpu(lease->mask), duration, ttl);

        /* make lease_rdcache_gen match directory */
        dir = dentry->d_parent->d_inode;
        di->lease_shared_gen = ceph_inode(dir)->i_shared_gen;

        if (lease->mask == 0)
                goto out_unlock;

        if (di->lease_gen == session->s_cap_gen &&
            time_before(ttl, dentry->d_time))
                goto out_unlock;  /* we already have a newer lease. */

        if (di->lease_session && di->lease_session != session)
                goto out_unlock;

        ceph_dentry_lru_touch(dentry);

        if (!di->lease_session)
                di->lease_session = ceph_get_mds_session(session);
        di->lease_gen = session->s_cap_gen;
        di->lease_seq = le32_to_cpu(lease->seq);
        di->lease_renew_after = half_ttl;
        di->lease_renew_from = 0;
        dentry->d_time = ttl;
out_unlock:
        spin_unlock(&dentry->d_lock);
        return;
}

/*
 * Set dentry's directory position based on the current dir's max, and
 * order it in d_subdirs, so that dcache_readdir behaves.
 */
static void ceph_set_dentry_offset(struct dentry *dn)
{
        struct dentry *dir = dn->d_parent;
        struct inode *inode = dn->d_parent->d_inode;
        struct ceph_dentry_info *di;

        BUG_ON(!inode);

        di = ceph_dentry(dn);

        spin_lock(&inode->i_lock);
        if ((ceph_inode(inode)->i_ceph_flags & CEPH_I_COMPLETE) == 0) {
                spin_unlock(&inode->i_lock);
                return;
        }
        di->offset = ceph_inode(inode)->i_max_offset++;
        spin_unlock(&inode->i_lock);

        spin_lock(&dir->d_lock);
        spin_lock_nested(&dn->d_lock, DENTRY_D_LOCK_NESTED);
        list_move(&dn->d_u.d_child, &dir->d_subdirs);
        dout("set_dentry_offset %p %lld (%p %p)\n", dn, di->offset,
             dn->d_u.d_child.prev, dn->d_u.d_child.next);
        spin_unlock(&dn->d_lock);
        spin_unlock(&dir->d_lock);
}

/*
 * splice a dentry to an inode.
 * caller must hold directory i_mutex for this to be safe.
 *
 * we will only rehash the resulting dentry if @prehash is
 * true; @prehash will be set to false (for the benefit of
 * the caller) if we fail.
 */
static struct dentry *splice_dentry(struct dentry *dn, struct inode *in,
                                    bool *prehash, bool set_offset)
{
        struct dentry *realdn;

        BUG_ON(dn->d_inode);

        /* dn must be unhashed */
        if (!d_unhashed(dn))
                d_drop(dn);
        realdn = d_materialise_unique(dn, in);
        if (IS_ERR(realdn)) {
                pr_err("splice_dentry error %ld %p inode %p ino %llx.%llx\n",
                       PTR_ERR(realdn), dn, in, ceph_vinop(in));
                if (prehash)
                        *prehash = false; /* don't rehash on error */
                dn = realdn; /* note realdn contains the error */
                goto out;
        } else if (realdn) {
                dout("dn %p (%d) spliced with %p (%d) "
                     "inode %p ino %llx.%llx\n",
                     dn, dn->d_count,
                     realdn, realdn->d_count,
                     realdn->d_inode, ceph_vinop(realdn->d_inode));
                dput(dn);
                dn = realdn;
        } else {
                BUG_ON(!ceph_dentry(dn));
                dout("dn %p attached to %p ino %llx.%llx\n",
                     dn, dn->d_inode, ceph_vinop(dn->d_inode));
        }
        if ((!prehash || *prehash) && d_unhashed(dn))
                d_rehash(dn);
        if (set_offset)
                ceph_set_dentry_offset(dn);
out:
        return dn;
}

/*
 * Incorporate results into the local cache.  This is either just
 * one inode, or a directory, dentry, and possibly linked-to inode (e.g.,
 * after a lookup).
 *
 * A reply may contain
 *         a directory inode along with a dentry.
 *  and/or a target inode
 *
 * Called with snap_rwsem (read).
 */
int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
                    struct ceph_mds_session *session)
{
        struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
        struct inode *in = NULL;
        struct ceph_mds_reply_inode *ininfo;
        struct ceph_vino vino;
        struct ceph_fs_client *fsc = ceph_sb_to_client(sb);
        int i = 0;
        int err = 0;

        dout("fill_trace %p is_dentry %d is_target %d\n", req,
             rinfo->head->is_dentry, rinfo->head->is_target);

#if 0
        /*
         * Debugging hook:
         *
         * If we resend completed ops to a recovering mds, we get no
         * trace.  Since that is very rare, pretend this is the case
         * to ensure the 'no trace' handlers in the callers behave.
         *
         * Fill in inodes unconditionally to avoid breaking cap
         * invariants.
         */
        if (rinfo->head->op & CEPH_MDS_OP_WRITE) {
                pr_info("fill_trace faking empty trace on %lld %s\n",
                        req->r_tid, ceph_mds_op_name(rinfo->head->op));
                if (rinfo->head->is_dentry) {
                        rinfo->head->is_dentry = 0;
                        err = fill_inode(req->r_locked_dir,
                                         &rinfo->diri, rinfo->dirfrag,
                                         session, req->r_request_started, -1);
                }
                if (rinfo->head->is_target) {
                        rinfo->head->is_target = 0;
                        ininfo = rinfo->targeti.in;
                        vino.ino = le64_to_cpu(ininfo->ino);
                        vino.snap = le64_to_cpu(ininfo->snapid);
                        in = ceph_get_inode(sb, vino);
                        err = fill_inode(in, &rinfo->targeti, NULL,
                                         session, req->r_request_started,
                                         req->r_fmode);
                        iput(in);
                }
        }
#endif

        if (!rinfo->head->is_target && !rinfo->head->is_dentry) {
                dout("fill_trace reply is empty!\n");
                if (rinfo->head->result == 0 && req->r_locked_dir)
                        ceph_invalidate_dir_request(req);
                return 0;
        }

        if (rinfo->head->is_dentry) {
                struct inode *dir = req->r_locked_dir;

                err = fill_inode(dir, &rinfo->diri, rinfo->dirfrag,
                                 session, req->r_request_started, -1,
                                 &req->r_caps_reservation);
                if (err < 0)
                        return err;
        }

        /*
         * ignore null lease/binding on snapdir ENOENT, or else we
         * will have trouble splicing in the virtual snapdir later
         */
        if (rinfo->head->is_dentry && !req->r_aborted &&
            (rinfo->head->is_target || strncmp(req->r_dentry->d_name.name,
                                               fsc->mount_options->snapdir_name,
                                               req->r_dentry->d_name.len))) {
                /*
                 * lookup link rename   : null -> possibly existing inode
                 * mknod symlink mkdir  : null -> new inode
                 * unlink               : linked -> null
                 */
                struct inode *dir = req->r_locked_dir;
                struct dentry *dn = req->r_dentry;
                bool have_dir_cap, have_lease;

                BUG_ON(!dn);
                BUG_ON(!dir);
                BUG_ON(dn->d_parent->d_inode != dir);
                BUG_ON(ceph_ino(dir) !=
                       le64_to_cpu(rinfo->diri.in->ino));
                BUG_ON(ceph_snap(dir) !=
                       le64_to_cpu(rinfo->diri.in->snapid));

                /* do we have a lease on the whole dir? */
                have_dir_cap =
                        (le32_to_cpu(rinfo->diri.in->cap.caps) &
                         CEPH_CAP_FILE_SHARED);

                /* do we have a dn lease? */
                have_lease = have_dir_cap ||
                        (le16_to_cpu(rinfo->dlease->mask) &
                         CEPH_LOCK_DN);

                if (!have_lease)
                        dout("fill_trace  no dentry lease or dir cap\n");

                /* rename? */
                if (req->r_old_dentry && req->r_op == CEPH_MDS_OP_RENAME) {
                        dout(" src %p '%.*s' dst %p '%.*s'\n",
                             req->r_old_dentry,
                             req->r_old_dentry->d_name.len,
                             req->r_old_dentry->d_name.name,
                             dn, dn->d_name.len, dn->d_name.name);
                        dout("fill_trace doing d_move %p -> %p\n",
                             req->r_old_dentry, dn);

                        /* d_move screws up d_subdirs order */
                        ceph_i_clear(dir, CEPH_I_COMPLETE);

                        d_move(req->r_old_dentry, dn);
                        dout(" src %p '%.*s' dst %p '%.*s'\n",
                             req->r_old_dentry,
                             req->r_old_dentry->d_name.len,
                             req->r_old_dentry->d_name.name,
                             dn, dn->d_name.len, dn->d_name.name);

                        /* ensure target dentry is invalidated, despite
                           rehashing bug in vfs_rename_dir */
                        ceph_invalidate_dentry_lease(dn);

                        /* take overwritten dentry's readdir offset */
                        dout("dn %p gets %p offset %lld (old offset %lld)\n",
                             req->r_old_dentry, dn, ceph_dentry(dn)->offset,
                             ceph_dentry(req->r_old_dentry)->offset);
                        ceph_dentry(req->r_old_dentry)->offset =
                                ceph_dentry(dn)->offset;

                        dn = req->r_old_dentry;  /* use old_dentry */
                        in = dn->d_inode;
                }

                /* null dentry? */
                if (!rinfo->head->is_target) {
                        dout("fill_trace null dentry\n");
                        if (dn->d_inode) {
                                dout("d_delete %p\n", dn);
                                d_delete(dn);
                        } else {
                                dout("d_instantiate %p NULL\n", dn);
                                d_instantiate(dn, NULL);
                                if (have_lease && d_unhashed(dn))
                                        d_rehash(dn);
                                update_dentry_lease(dn, rinfo->dlease,
                                                    session,
                                                    req->r_request_started);
                        }
                        goto done;
                }

                /* attach proper inode */
                ininfo = rinfo->targeti.in;
                vino.ino = le64_to_cpu(ininfo->ino);
                vino.snap = le64_to_cpu(ininfo->snapid);
                in = dn->d_inode;
                if (!in) {
                        in = ceph_get_inode(sb, vino);
                        if (IS_ERR(in)) {
                                pr_err("fill_trace bad get_inode "
                                       "%llx.%llx\n", vino.ino, vino.snap);
                                err = PTR_ERR(in);
                                d_delete(dn);
                                goto done;
                        }
                        dn = splice_dentry(dn, in, &have_lease, true);
                        if (IS_ERR(dn)) {
                                err = PTR_ERR(dn);
                                goto done;
                        }
                        req->r_dentry = dn;  /* may have spliced */
                        igrab(in);
                } else if (ceph_ino(in) == vino.ino &&
                           ceph_snap(in) == vino.snap) {
                        igrab(in);
                } else {
                        dout(" %p links to %p %llx.%llx, not %llx.%llx\n",
                             dn, in, ceph_ino(in), ceph_snap(in),
                             vino.ino, vino.snap);
                        have_lease = false;
                        in = NULL;
                }

                if (have_lease)
                        update_dentry_lease(dn, rinfo->dlease, session,
                                            req->r_request_started);
                dout(" final dn %p\n", dn);
                i++;
        } else if (req->r_op == CEPH_MDS_OP_LOOKUPSNAP ||
                   req->r_op == CEPH_MDS_OP_MKSNAP) {
                struct dentry *dn = req->r_dentry;

                /* fill out a snapdir LOOKUPSNAP dentry */
                BUG_ON(!dn);
                BUG_ON(!req->r_locked_dir);
                BUG_ON(ceph_snap(req->r_locked_dir) != CEPH_SNAPDIR);
                ininfo = rinfo->targeti.in;
                vino.ino = le64_to_cpu(ininfo->ino);
                vino.snap = le64_to_cpu(ininfo->snapid);
                in = ceph_get_inode(sb, vino);
                if (IS_ERR(in)) {
                        pr_err("fill_inode get_inode badness %llx.%llx\n",
                               vino.ino, vino.snap);
                        err = PTR_ERR(in);
                        d_delete(dn);
                        goto done;
                }
                dout(" linking snapped dir %p to dn %p\n", in, dn);
                dn = splice_dentry(dn, in, NULL, true);
                if (IS_ERR(dn)) {
                        err = PTR_ERR(dn);
                        goto done;
                }
                req->r_dentry = dn;  /* may have spliced */
                igrab(in);
                rinfo->head->is_dentry = 1;  /* fool notrace handlers */
        }

        if (rinfo->head->is_target) {
                vino.ino = le64_to_cpu(rinfo->targeti.in->ino);
                vino.snap = le64_to_cpu(rinfo->targeti.in->snapid);

                if (in == NULL || ceph_ino(in) != vino.ino ||
                    ceph_snap(in) != vino.snap) {
                        in = ceph_get_inode(sb, vino);
                        if (IS_ERR(in)) {
                                err = PTR_ERR(in);
                                goto done;
                        }
                }
                req->r_target_inode = in;

                err = fill_inode(in,
                                 &rinfo->targeti, NULL,
                                 session, req->r_request_started,
                                 (le32_to_cpu(rinfo->head->result) == 0) ?
                                 req->r_fmode : -1,
                                 &req->r_caps_reservation);
                if (err < 0) {
                        pr_err("fill_inode badness %p %llx.%llx\n",
                               in, ceph_vinop(in));
                        goto done;
                }
        }

done:
        dout("fill_trace done err=%d\n", err);
        return err;
}

/*
 * Prepopulate our cache with readdir results, leases, etc.
 */
int ceph_readdir_prepopulate(struct ceph_mds_request *req,
                             struct ceph_mds_session *session)
{
        struct dentry *parent = req->r_dentry;
        struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
        struct qstr dname;
        struct dentry *dn;
        struct inode *in;
        int err = 0, i;
        struct inode *snapdir = NULL;
        struct ceph_mds_request_head *rhead = req->r_request->front.iov_base;
        u64 frag = le32_to_cpu(rhead->args.readdir.frag);
        struct ceph_dentry_info *di;

        if (le32_to_cpu(rinfo->head->op) == CEPH_MDS_OP_LSSNAP) {
                snapdir = ceph_get_snapdir(parent->d_inode);
                parent = d_find_alias(snapdir);
                dout("readdir_prepopulate %d items under SNAPDIR dn %p\n",
                     rinfo->dir_nr, parent);
        } else {
                dout("readdir_prepopulate %d items under dn %p\n",
                     rinfo->dir_nr, parent);
                if (rinfo->dir_dir)
                        ceph_fill_dirfrag(parent->d_inode, rinfo->dir_dir);
        }

        for (i = 0; i < rinfo->dir_nr; i++) {
                struct ceph_vino vino;

                dname.name = rinfo->dir_dname[i];
                dname.len = rinfo->dir_dname_len[i];
                dname.hash = full_name_hash(dname.name, dname.len);

                vino.ino = le64_to_cpu(rinfo->dir_in[i].in->ino);
                vino.snap = le64_to_cpu(rinfo->dir_in[i].in->snapid);

retry_lookup:
                dn = d_lookup(parent, &dname);
                dout("d_lookup on parent=%p name=%.*s got %p\n",
                     parent, dname.len, dname.name, dn);

                if (!dn) {
                        dn = d_alloc(parent, &dname);
                        dout("d_alloc %p '%.*s' = %p\n", parent,
                             dname.len, dname.name, dn);
                        if (dn == NULL) {
                                dout("d_alloc badness\n");
                                err = -ENOMEM;
                                goto out;
                        }
                        err = ceph_init_dentry(dn);
                        if (err < 0) {
                                dput(dn);
                                goto out;
                        }
                } else if (dn->d_inode &&
                           (ceph_ino(dn->d_inode) != vino.ino ||
                            ceph_snap(dn->d_inode) != vino.snap)) {
                        dout(" dn %p points to wrong inode %p\n",
                             dn, dn->d_inode);
                        d_delete(dn);
                        dput(dn);
                        goto retry_lookup;
                } else {
                        /* reorder parent's d_subdirs */
                        spin_lock(&parent->d_lock);
                        spin_lock_nested(&dn->d_lock, DENTRY_D_LOCK_NESTED);
                        list_move(&dn->d_u.d_child, &parent->d_subdirs);
                        spin_unlock(&dn->d_lock);
                        spin_unlock(&parent->d_lock);
                }

                di = dn->d_fsdata;
                di->offset = ceph_make_fpos(frag, i + req->r_readdir_offset);

                /* inode */
                if (dn->d_inode) {
                        in = dn->d_inode;
                } else {
                        in = ceph_get_inode(parent->d_sb, vino);
                        if (IS_ERR(in)) {
                                dout("new_inode badness\n");
                                d_delete(dn);
                                dput(dn);
                                err = PTR_ERR(in);
                                goto out;
                        }
                        dn = splice_dentry(dn, in, NULL, false);
                        if (IS_ERR(dn))
                                dn = NULL;
                }

                if (fill_inode(in, &rinfo->dir_in[i], NULL, session,
                               req->r_request_started, -1,
                               &req->r_caps_reservation) < 0) {
                        pr_err("fill_inode badness on %p\n", in);
                        goto next_item;
                }
                if (dn)
                        update_dentry_lease(dn, rinfo->dir_dlease[i],
                                            req->r_session,
                                            req->r_request_started);
next_item:
                if (dn)
                        dput(dn);
        }
        req->r_did_prepopulate = true;

out:
        if (snapdir) {
                iput(snapdir);
                dput(parent);
        }
        dout("readdir_prepopulate done\n");
        return err;
}

int ceph_inode_set_size(struct inode *inode, loff_t size)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        int ret = 0;

        spin_lock(&inode->i_lock);
        dout("set_size %p %llu -> %llu\n", inode, inode->i_size, size);
        inode->i_size = size;
        inode->i_blocks = (size + (1 << 9) - 1) >> 9;

        /* tell the MDS if we are approaching max_size */
        if ((size << 1) >= ci->i_max_size &&
            (ci->i_reported_size << 1) < ci->i_max_size)
                ret = 1;

        spin_unlock(&inode->i_lock);
        return ret;
}

/*
 * Write back inode data in a worker thread.  (This can't be done
 * in the message handler context.)
 */
void ceph_queue_writeback(struct inode *inode)
{
        if (queue_work(ceph_inode_to_client(inode)->wb_wq,
                       &ceph_inode(inode)->i_wb_work)) {
                dout("ceph_queue_writeback %p\n", inode);
                igrab(inode);
        } else {
                dout("ceph_queue_writeback %p failed\n", inode);
        }
}

static void ceph_writeback_work(struct work_struct *work)
{
        struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
                                                  i_wb_work);
        struct inode *inode = &ci->vfs_inode;

        dout("writeback %p\n", inode);
        filemap_fdatawrite(&inode->i_data);
        iput(inode);
}

/*
 * queue an async invalidation
 */
void ceph_queue_invalidate(struct inode *inode)
{
        if (queue_work(ceph_inode_to_client(inode)->pg_inv_wq,
                       &ceph_inode(inode)->i_pg_inv_work)) {
                dout("ceph_queue_invalidate %p\n", inode);
                igrab(inode);
        } else {
                dout("ceph_queue_invalidate %p failed\n", inode);
        }
}

/*
 * invalidate any pages that are not dirty or under writeback.  this
 * includes pages that are clean and mapped.
 */
static void ceph_invalidate_nondirty_pages(struct address_space *mapping)
{
        struct pagevec pvec;
        pgoff_t next = 0;
        int i;

        pagevec_init(&pvec, 0);
        while (pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
                for (i = 0; i < pagevec_count(&pvec); i++) {
                        struct page *page = pvec.pages[i];
                        pgoff_t index;
                        int skip_page =
                                (PageDirty(page) || PageWriteback(page));

                        if (!skip_page)
                                skip_page = !trylock_page(page);

                        /*
                         * We really shouldn't be looking at the ->index of an
                         * unlocked page.  But we're not allowed to lock these
                         * pages.  So we rely upon nobody altering the ->index
                         * of this (pinned-by-us) page.
                         */
                        index = page->index;
                        if (index > next)
                                next = index;
                        next++;

                        if (skip_page)
                                continue;

                        generic_error_remove_page(mapping, page);
                        unlock_page(page);
                }
                pagevec_release(&pvec);
                cond_resched();
        }
}

/*
 * Invalidate inode pages in a worker thread.  (This can't be done
 * in the message handler context.)
 */
static void ceph_invalidate_work(struct work_struct *work)
{
        struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
                                                  i_pg_inv_work);
        struct inode *inode = &ci->vfs_inode;
        u32 orig_gen;
        int check = 0;

        spin_lock(&inode->i_lock);
        dout("invalidate_pages %p gen %d revoking %d\n", inode,
             ci->i_rdcache_gen, ci->i_rdcache_revoking);
        if (ci->i_rdcache_revoking != ci->i_rdcache_gen) {
                /* nevermind! */
                spin_unlock(&inode->i_lock);
                goto out;
        }
        orig_gen = ci->i_rdcache_gen;
        spin_unlock(&inode->i_lock);

        ceph_invalidate_nondirty_pages(inode->i_mapping);

        spin_lock(&inode->i_lock);
        if (orig_gen == ci->i_rdcache_gen &&
            orig_gen == ci->i_rdcache_revoking) {
                dout("invalidate_pages %p gen %d successful\n", inode,
                     ci->i_rdcache_gen);
                ci->i_rdcache_revoking--;
                check = 1;
        } else {
                dout("invalidate_pages %p gen %d raced, now %d revoking %d\n",
                     inode, orig_gen, ci->i_rdcache_gen,
                     ci->i_rdcache_revoking);
        }
        spin_unlock(&inode->i_lock);

        if (check)
                ceph_check_caps(ci, 0, NULL);
out:
        iput(inode);
}


/*
 * called by trunc_wq; take i_mutex ourselves
 *
 * We also truncate in a separate thread as well.
 */
static void ceph_vmtruncate_work(struct work_struct *work)
{
        struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
                                                  i_vmtruncate_work);
        struct inode *inode = &ci->vfs_inode;

        dout("vmtruncate_work %p\n", inode);
        mutex_lock(&inode->i_mutex);
        __ceph_do_pending_vmtruncate(inode);
        mutex_unlock(&inode->i_mutex);
        iput(inode);
}

/*
 * Queue an async vmtruncate.  If we fail to queue work, we will handle
 * the truncation the next time we call __ceph_do_pending_vmtruncate.
 */
void ceph_queue_vmtruncate(struct inode *inode)
{
        struct ceph_inode_info *ci = ceph_inode(inode);

        if (queue_work(ceph_sb_to_client(inode->i_sb)->trunc_wq,
                       &ci->i_vmtruncate_work)) {
                dout("ceph_queue_vmtruncate %p\n", inode);
                igrab(inode);
        } else {
                dout("ceph_queue_vmtruncate %p failed, pending=%d\n",
                     inode, ci->i_truncate_pending);
        }
}

/*
 * called with i_mutex held.
 *
 * Make sure any pending truncation is applied before doing anything
 * that may depend on it.
 */
void __ceph_do_pending_vmtruncate(struct inode *inode)
{
        struct ceph_inode_info *ci = ceph_inode(inode);
        u64 to;
        int wrbuffer_refs, wake = 0;

retry:
        spin_lock(&inode->i_lock);
        if (ci->i_truncate_pending == 0) {
                dout("__do_pending_vmtruncate %p none pending\n", inode);
                spin_unlock(&inode->i_lock);
                return;
        }

        /*
         * make sure any dirty snapped pages are flushed before we
         * possibly truncate them.. so write AND block!
         */
        if (ci->i_wrbuffer_ref_head < ci->i_wrbuffer_ref) {
                dout("__do_pending_vmtruncate %p flushing snaps first\n",
                     inode);
                spin_unlock(&inode->i_lock);
                filemap_write_and_wait_range(&inode->i_data, 0,
                                             inode->i_sb->s_maxbytes);
                goto retry;
        }

        to = ci->i_truncate_size;
        wrbuffer_refs = ci->i_wrbuffer_ref;
        dout("__do_pending_vmtruncate %p (%d) to %lld\n", inode,
             ci->i_truncate_pending, to);
        spin_unlock(&inode->i_lock);

        truncate_inode_pages(inode->i_mapping, to);

        spin_lock(&inode->i_lock);
        ci->i_truncate_pending--;
        if (ci->i_truncate_pending == 0)
                wake = 1;
        spin_unlock(&inode->i_lock);

        if (wrbuffer_refs == 0)
                ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
        if (wake)
                wake_up_all(&ci->i_cap_wq);
}


/*
 * symlinks
 */
static void *ceph_sym_follow_link(struct dentry *dentry, struct nameidata *nd)
{
        struct ceph_inode_info *ci = ceph_inode(dentry->d_inode);
        nd_set_link(nd, ci->i_symlink);
        return NULL;
}

static const struct inode_operations ceph_symlink_iops = {
        .readlink = generic_readlink,
        .follow_link = ceph_sym_follow_link,
};

/*
 * setattr
 */
int ceph_setattr(struct dentry *dentry, struct iattr *attr)
{
        struct inode *inode = dentry->d_inode;
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct inode *parent_inode = dentry->d_parent->d_inode;
        const unsigned int ia_valid = attr->ia_valid;
        struct ceph_mds_request *req;
        struct ceph_mds_client *mdsc = ceph_sb_to_client(dentry->d_sb)->mdsc;
        int issued;
        int release = 0, dirtied = 0;
        int mask = 0;
        int err = 0;

        if (ceph_snap(inode) != CEPH_NOSNAP)
                return -EROFS;

        __ceph_do_pending_vmtruncate(inode);

        err = inode_change_ok(inode, attr);
        if (err != 0)
                return err;

        req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETATTR,
                                       USE_AUTH_MDS);
        if (IS_ERR(req))
                return PTR_ERR(req);

        spin_lock(&inode->i_lock);
        issued = __ceph_caps_issued(ci, NULL);
        dout("setattr %p issued %s\n", inode, ceph_cap_string(issued));

        if (ia_valid & ATTR_UID) {
                dout("setattr %p uid %d -> %d\n", inode,
                     inode->i_uid, attr->ia_uid);
                if (issued & CEPH_CAP_AUTH_EXCL) {
                        inode->i_uid = attr->ia_uid;
                        dirtied |= CEPH_CAP_AUTH_EXCL;
                } else if ((issued & CEPH_CAP_AUTH_SHARED) == 0 ||
                           attr->ia_uid != inode->i_uid) {
                        req->r_args.setattr.uid = cpu_to_le32(attr->ia_uid);
                        mask |= CEPH_SETATTR_UID;
                        release |= CEPH_CAP_AUTH_SHARED;
                }
        }
        if (ia_valid & ATTR_GID) {
                dout("setattr %p gid %d -> %d\n", inode,
                     inode->i_gid, attr->ia_gid);
                if (issued & CEPH_CAP_AUTH_EXCL) {
                        inode->i_gid = attr->ia_gid;
                        dirtied |= CEPH_CAP_AUTH_EXCL;
                } else if ((issued & CEPH_CAP_AUTH_SHARED) == 0 ||
                           attr->ia_gid != inode->i_gid) {
                        req->r_args.setattr.gid = cpu_to_le32(attr->ia_gid);
                        mask |= CEPH_SETATTR_GID;
                        release |= CEPH_CAP_AUTH_SHARED;
                }
        }
        if (ia_valid & ATTR_MODE) {
                dout("setattr %p mode 0%o -> 0%o\n", inode, inode->i_mode,
                     attr->ia_mode);
                if (issued & CEPH_CAP_AUTH_EXCL) {
                        inode->i_mode = attr->ia_mode;
                        dirtied |= CEPH_CAP_AUTH_EXCL;
                } else if ((issued & CEPH_CAP_AUTH_SHARED) == 0 ||
                           attr->ia_mode != inode->i_mode) {
                        req->r_args.setattr.mode = cpu_to_le32(attr->ia_mode);
                        mask |= CEPH_SETATTR_MODE;
                        release |= CEPH_CAP_AUTH_SHARED;
                }
        }

        if (ia_valid & ATTR_ATIME) {
                dout("setattr %p atime %ld.%ld -> %ld.%ld\n", inode,
                     inode->i_atime.tv_sec, inode->i_atime.tv_nsec,
                     attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec);
                if (issued & CEPH_CAP_FILE_EXCL) {
                        ci->i_time_warp_seq++;
                        inode->i_atime = attr->ia_atime;
                        dirtied |= CEPH_CAP_FILE_EXCL;
                } else if ((issued & CEPH_CAP_FILE_WR) &&
                           timespec_compare(&inode->i_atime,
                                            &attr->ia_atime) < 0) {
                        inode->i_atime = attr->ia_atime;
                        dirtied |= CEPH_CAP_FILE_WR;
                } else if ((issued & CEPH_CAP_FILE_SHARED) == 0 ||
                           !timespec_equal(&inode->i_atime, &attr->ia_atime)) {
                        ceph_encode_timespec(&req->r_args.setattr.atime,
                                             &attr->ia_atime);
                        mask |= CEPH_SETATTR_ATIME;
                        release |= CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_RD |
                                CEPH_CAP_FILE_WR;
                }
        }
        if (ia_valid & ATTR_MTIME) {
                dout("setattr %p mtime %ld.%ld -> %ld.%ld\n", inode,
                     inode->i_mtime.tv_sec, inode->i_mtime.tv_nsec,
                     attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec);
                if (issued & CEPH_CAP_FILE_EXCL) {
                        ci->i_time_warp_seq++;
                        inode->i_mtime = attr->ia_mtime;
                        dirtied |= CEPH_CAP_FILE_EXCL;
                } else if ((issued & CEPH_CAP_FILE_WR) &&
                           timespec_compare(&inode->i_mtime,
                                            &attr->ia_mtime) < 0) {
                        inode->i_mtime = attr->ia_mtime;
                        dirtied |= CEPH_CAP_FILE_WR;
                } else if ((issued & CEPH_CAP_FILE_SHARED) == 0 ||
                           !timespec_equal(&inode->i_mtime, &attr->ia_mtime)) {
                        ceph_encode_timespec(&req->r_args.setattr.mtime,
                                             &attr->ia_mtime);
                        mask |= CEPH_SETATTR_MTIME;
                        release |= CEPH_CAP_FILE_SHARED | CEPH_CAP_FILE_RD |
                                CEPH_CAP_FILE_WR;
                }
        }
        if (ia_valid & ATTR_SIZE) {
                dout("setattr %p size %lld -> %lld\n", inode,
                     inode->i_size, attr->ia_size);
                if (attr->ia_size > inode->i_sb->s_maxbytes) {
                        err = -EINVAL;
                        goto out;
                }
                if ((issued & CEPH_CAP_FILE_EXCL) &&
                    attr->ia_size > inode->i_size) {
                        inode->i_size = attr->ia_size;
                        inode->i_blocks =
                                (attr->ia_size + (1 << 9) - 1) >> 9;
                        inode->i_ctime = attr->ia_ctime;
                        ci->i_reported_size = attr->ia_size;
                        dirtied |= CEPH_CAP_FILE_EXCL;
                } else if ((issued & CEPH_CAP_FILE_SHARED) == 0 ||
                           attr->ia_size != inode->i_size) {
                        req->r_args.setattr.size = cpu_to_le64(attr->ia_size);
                        req->r_args.setattr.old_size =
                                cpu_to_le64(inode->i_size);
                        mask |= CEPH_SETATTR_SIZE;
                        release |= CEPH_CAP_FILE_SHARED | CEPH_CAP_FILE_RD |
                                CEPH_CAP_FILE_WR;
                }
        }

        /* these do nothing */
        if (ia_valid & ATTR_CTIME) {
                bool only = (ia_valid & (ATTR_SIZE|ATTR_MTIME|ATTR_ATIME|
                                         ATTR_MODE|ATTR_UID|ATTR_GID)) == 0;
                dout("setattr %p ctime %ld.%ld -> %ld.%ld (%s)\n", inode,
                     inode->i_ctime.tv_sec, inode->i_ctime.tv_nsec,
                     attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec,
                     only ? "ctime only" : "ignored");
                inode->i_ctime = attr->ia_ctime;
                if (only) {
                        /*
                         * if kernel wants to dirty ctime but nothing else,
                         * we need to choose a cap to dirty under, or do
                         * a almost-no-op setattr
                         */
                        if (issued & CEPH_CAP_AUTH_EXCL)
                                dirtied |= CEPH_CAP_AUTH_EXCL;
                        else if (issued & CEPH_CAP_FILE_EXCL)
                                dirtied |= CEPH_CAP_FILE_EXCL;
                        else if (issued & CEPH_CAP_XATTR_EXCL)
                                dirtied |= CEPH_CAP_XATTR_EXCL;
                        else
                                mask |= CEPH_SETATTR_CTIME;
                }
        }
        if (ia_valid & ATTR_FILE)
                dout("setattr %p ATTR_FILE ... hrm!\n", inode);

        if (dirtied) {
                __ceph_mark_dirty_caps(ci, dirtied);
                inode->i_ctime = CURRENT_TIME;
        }

        release &= issued;
        spin_unlock(&inode->i_lock);

        if (mask) {
                req->r_inode = igrab(inode);
                req->r_inode_drop = release;
                req->r_args.setattr.mask = cpu_to_le32(mask);
                req->r_num_caps = 1;
                err = ceph_mdsc_do_request(mdsc, parent_inode, req);
        }
        dout("setattr %p result=%d (%s locally, %d remote)\n", inode, err,
             ceph_cap_string(dirtied), mask);

        ceph_mdsc_put_request(req);
        __ceph_do_pending_vmtruncate(inode);
        return err;
out:
        spin_unlock(&inode->i_lock);
        ceph_mdsc_put_request(req);
        return err;
}

/*
 * Verify that we have a lease on the given mask.  If not,
 * do a getattr against an mds.
 */
int ceph_do_getattr(struct inode *inode, int mask)
{
        struct ceph_fs_client *fsc = ceph_sb_to_client(inode->i_sb);
        struct ceph_mds_client *mdsc = fsc->mdsc;
        struct ceph_mds_request *req;
        int err;

        if (ceph_snap(inode) == CEPH_SNAPDIR) {
                dout("do_getattr inode %p SNAPDIR\n", inode);
                return 0;
        }

        dout("do_getattr inode %p mask %s mode 0%o\n", inode, ceph_cap_string(mask), inode->i_mode);
        if (ceph_caps_issued_mask(ceph_inode(inode), mask, 1))
                return 0;

        req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_GETATTR, USE_ANY_MDS);
        if (IS_ERR(req))
                return PTR_ERR(req);
        req->r_inode = igrab(inode);
        req->r_num_caps = 1;
        req->r_args.getattr.mask = cpu_to_le32(mask);
        err = ceph_mdsc_do_request(mdsc, NULL, req);
        ceph_mdsc_put_request(req);
        dout("do_getattr result=%d\n", err);
        return err;
}


/*
 * Check inode permissions.  We verify we have a valid value for
 * the AUTH cap, then call the generic handler.
 */
int ceph_permission(struct inode *inode, int mask, unsigned int flags)
{
        int err;

        if (flags & IPERM_FLAG_RCU)
                return -ECHILD;

        err = ceph_do_getattr(inode, CEPH_CAP_AUTH_SHARED);

        if (!err)
                err = generic_permission(inode, mask, flags, NULL);
        return err;
}

/*
 * Get all attributes.  Hopefully somedata we'll have a statlite()
 * and can limit the fields we require to be accurate.
 */
int ceph_getattr(struct vfsmount *mnt, struct dentry *dentry,
                 struct kstat *stat)
{
        struct inode *inode = dentry->d_inode;
        struct ceph_inode_info *ci = ceph_inode(inode);
        int err;

        err = ceph_do_getattr(inode, CEPH_STAT_CAP_INODE_ALL);
        if (!err) {
                generic_fillattr(inode, stat);
                stat->ino = inode->i_ino;
                if (ceph_snap(inode) != CEPH_NOSNAP)
                        stat->dev = ceph_snap(inode);
                else
                        stat->dev = 0;
                if (S_ISDIR(inode->i_mode)) {
                        if (ceph_test_mount_opt(ceph_sb_to_client(inode->i_sb),
                                                RBYTES))
                                stat->size = ci->i_rbytes;
                        else
                                stat->size = ci->i_files + ci->i_subdirs;
                        stat->blocks = 0;
                        stat->blksize = 65536;
                }
        }
        return err;
}