inode.c

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#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 "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
 */
static int ceph_set_ino_cb(struct inode *inode, void *data)
{
    ceph_inode(inode)->i_vino = *(struct ceph_vino *)data;
    inode->i_ino = ceph_vino_to_ino(*(struct ceph_vino *)data);
    return 0;
}

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);

    spin_lock_init(&ci->i_ceph_lock);

    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_wb_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);

    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 = 0, implemented;
    int updating_inode = 0;
    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(&ci->i_ceph_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;
    
    updating_inode = 1;
    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)
        set_nlink(inode, 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) {
            u32 symlen = iinfo->symlink_len;
            char *sym;

            spin_unlock(&ci->i_ceph_lock);

            err = -EINVAL;
            if (WARN_ON(symlen != inode->i_size))
                goto out;

            err = -ENOMEM;
            sym = kstrndup(iinfo->symlink, symlen, GFP_NOFS);
            if (!sym)
                goto out;

            spin_lock(&ci->i_ceph_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);
        break;
    default:
        pr_err("fill_inode %llx.%llx BAD mode 0%o\n",
               ceph_vinop(inode), inode->i_mode);
    }

no_change:
    spin_unlock(&ci->i_ceph_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(&ci->i_ceph_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(&ci->i_ceph_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);
    }

    /* set dir completion flag? */
    if (S_ISDIR(inode->i_mode) &&
        updating_inode &&                 /* didn't jump to no_change */
        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 &&
        !ceph_dir_test_complete(inode)) {
        dout(" marking %p complete (empty)\n", inode);
        ceph_dir_set_complete(inode);
        ci->i_max_offset = 2;
    }

    /* 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 duration %lu ms ttl %lu\n",
         dentry, 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 (duration == 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.
 *
 * Always called under directory's i_mutex.
 */
static void ceph_set_dentry_offset(struct dentry *dn)
{
    struct dentry *dir = dn->d_parent;
    struct inode *inode = dir->d_inode;
    struct ceph_inode_info *ci;
    struct ceph_dentry_info *di;

    BUG_ON(!inode);

    ci = ceph_inode(inode);
    di = ceph_dentry(dn);

    spin_lock(&ci->i_ceph_lock);
    if (!ceph_dir_test_complete(inode)) {
        spin_unlock(&ci->i_ceph_lock);
        return;
    }
    di->offset = ceph_inode(inode)->i_max_offset++;
    spin_unlock(&ci->i_ceph_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;

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

    /*
     * 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 &&
        req->r_locked_dir &&
        (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 ||
            le32_to_cpu(rinfo->dlease->duration_ms);
        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(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);

            /*
             * d_move() puts the renamed dentry at the end of
             * d_subdirs.  We need to assign it an appropriate
             * directory offset so we can behave when holding
             * D_COMPLETE.
             */
            ceph_set_dentry_offset(req->r_old_dentry);
            dout("dn %p gets new offset %lld\n", req->r_old_dentry, 
                 ceph_dentry(req->r_old_dentry)->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_drop(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 */
            ihold(in);
        } else if (ceph_ino(in) == vino.ino &&
               ceph_snap(in) == vino.snap) {
            ihold(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 */
        ihold(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_drop(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(&ci->i_ceph_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(&ci->i_ceph_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)
{
    ihold(inode);
    if (queue_work(ceph_inode_to_client(inode)->wb_wq,
               &ceph_inode(inode)->i_wb_work)) {
        dout("ceph_queue_writeback %p\n", inode);
    } else {
        dout("ceph_queue_writeback %p failed\n", inode);
        iput(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)
{
    ihold(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);
    } else {
        dout("ceph_queue_invalidate %p failed\n", inode);
        iput(inode);
    }
}

/*
 * 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(&ci->i_ceph_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(&ci->i_ceph_lock);
        goto out;
    }
    orig_gen = ci->i_rdcache_gen;
    spin_unlock(&ci->i_ceph_lock);

    truncate_inode_pages(&inode->i_data, 0);

    spin_lock(&ci->i_ceph_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(&ci->i_ceph_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);

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

/*
 * 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(&ci->i_ceph_lock);
    if (ci->i_truncate_pending == 0) {
        dout("__do_pending_vmtruncate %p none pending\n", inode);
        spin_unlock(&ci->i_ceph_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(&ci->i_ceph_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(&ci->i_ceph_lock);

    truncate_inode_pages(inode->i_mapping, to);

    spin_lock(&ci->i_ceph_lock);
    ci->i_truncate_pending--;
    if (ci->i_truncate_pending == 0)
        wake = 1;
    spin_unlock(&ci->i_ceph_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;
    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;
    int inode_dirty_flags = 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(&ci->i_ceph_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) {
        inode_dirty_flags = __ceph_mark_dirty_caps(ci, dirtied);
        inode->i_ctime = CURRENT_TIME;
    }

    release &= issued;
    spin_unlock(&ci->i_ceph_lock);

    if (inode_dirty_flags)
        __mark_inode_dirty(inode, inode_dirty_flags);

    if (mask) {
        req->r_inode = inode;
        ihold(inode);
        req->r_inode_drop = release;
        req->r_args.setattr.mask = cpu_to_le32(mask);
        req->r_num_caps = 1;
        parent_inode = ceph_get_dentry_parent_inode(dentry);
        err = ceph_mdsc_do_request(mdsc, parent_inode, req);
        iput(parent_inode);
    }
    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(&ci->i_ceph_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 = inode;
    ihold(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)
{
    int err;

    if (mask & MAY_NOT_BLOCK)
        return -ECHILD;

    err = ceph_do_getattr(inode, CEPH_CAP_AUTH_SHARED);

    if (!err)
        err = generic_permission(inode, mask);
    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 = ceph_translate_ino(inode->i_sb, 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;
}