dir.c

Go to the documentation of this file.

#include <linux/ceph/ceph_debug.h>

#include <linux/spinlock.h>
#include <linux/fs_struct.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/sched.h>

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

/*
 * Directory operations: readdir, lookup, create, link, unlink,
 * rename, etc.
 */

/*
 * Ceph MDS operations are specified in terms of a base ino and
 * relative path.  Thus, the client can specify an operation on a
 * specific inode (e.g., a getattr due to fstat(2)), or as a path
 * relative to, say, the root directory.
 *
 * Normally, we limit ourselves to strict inode ops (no path component)
 * or dentry operations (a single path component relative to an ino).  The
 * exception to this is open_root_dentry(), which will open the mount
 * point by name.
 */

const struct inode_operations ceph_dir_iops;
const struct file_operations ceph_dir_fops;
const struct dentry_operations ceph_dentry_ops;

/*
 * Initialize ceph dentry state.
 */
int ceph_init_dentry(struct dentry *dentry)
{
    struct ceph_dentry_info *di;

    if (dentry->d_fsdata)
        return 0;

    di = kmem_cache_alloc(ceph_dentry_cachep, GFP_NOFS | __GFP_ZERO);
    if (!di)
        return -ENOMEM;          /* oh well */

    spin_lock(&dentry->d_lock);
    if (dentry->d_fsdata) {
        /* lost a race */
        kmem_cache_free(ceph_dentry_cachep, di);
        goto out_unlock;
    }

    if (ceph_snap(dentry->d_parent->d_inode) == CEPH_NOSNAP)
        d_set_d_op(dentry, &ceph_dentry_ops);
    else if (ceph_snap(dentry->d_parent->d_inode) == CEPH_SNAPDIR)
        d_set_d_op(dentry, &ceph_snapdir_dentry_ops);
    else
        d_set_d_op(dentry, &ceph_snap_dentry_ops);

    di->dentry = dentry;
    di->lease_session = NULL;
    dentry->d_time = jiffies;
    /* avoid reordering d_fsdata setup so that the check above is safe */
    smp_mb();
    dentry->d_fsdata = di;
    ceph_dentry_lru_add(dentry);
out_unlock:
    spin_unlock(&dentry->d_lock);
    return 0;
}

struct inode *ceph_get_dentry_parent_inode(struct dentry *dentry)
{
    struct inode *inode = NULL;

    if (!dentry)
        return NULL;

    spin_lock(&dentry->d_lock);
    if (!IS_ROOT(dentry)) {
        inode = dentry->d_parent->d_inode;
        ihold(inode);
    }
    spin_unlock(&dentry->d_lock);
    return inode;
}


/*
 * for readdir, we encode the directory frag and offset within that
 * frag into f_pos.
 */
static unsigned fpos_frag(loff_t p)
{
    return p >> 32;
}
static unsigned fpos_off(loff_t p)
{
    return p & 0xffffffff;
}

/*
 * When possible, we try to satisfy a readdir by peeking at the
 * dcache.  We make this work by carefully ordering dentries on
 * d_u.d_child when we initially get results back from the MDS, and
 * falling back to a "normal" sync readdir if any dentries in the dir
 * are dropped.
 *
 * D_COMPLETE tells indicates we have all dentries in the dir.  It is
 * defined IFF we hold CEPH_CAP_FILE_SHARED (which will be revoked by
 * the MDS if/when the directory is modified).
 */
static int __dcache_readdir(struct file *filp,
                void *dirent, filldir_t filldir)
{
    struct ceph_file_info *fi = filp->private_data;
    struct dentry *parent = filp->f_dentry;
    struct inode *dir = parent->d_inode;
    struct list_head *p;
    struct dentry *dentry, *last;
    struct ceph_dentry_info *di;
    int err = 0;

    /* claim ref on last dentry we returned */
    last = fi->dentry;
    fi->dentry = NULL;

    dout("__dcache_readdir %p at %llu (last %p)\n", dir, filp->f_pos,
         last);

    spin_lock(&parent->d_lock);

    /* start at beginning? */
    if (filp->f_pos == 2 || last == NULL ||
        filp->f_pos < ceph_dentry(last)->offset) {
        if (list_empty(&parent->d_subdirs))
            goto out_unlock;
        p = parent->d_subdirs.prev;
        dout(" initial p %p/%p\n", p->prev, p->next);
    } else {
        p = last->d_u.d_child.prev;
    }

more:
    dentry = list_entry(p, struct dentry, d_u.d_child);
    di = ceph_dentry(dentry);
    while (1) {
        dout(" p %p/%p %s d_subdirs %p/%p\n", p->prev, p->next,
             d_unhashed(dentry) ? "!hashed" : "hashed",
             parent->d_subdirs.prev, parent->d_subdirs.next);
        if (p == &parent->d_subdirs) {
            fi->flags |= CEPH_F_ATEND;
            goto out_unlock;
        }
        spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
        if (!d_unhashed(dentry) && dentry->d_inode &&
            ceph_snap(dentry->d_inode) != CEPH_SNAPDIR &&
            ceph_ino(dentry->d_inode) != CEPH_INO_CEPH &&
            filp->f_pos <= di->offset)
            break;
        dout(" skipping %p %.*s at %llu (%llu)%s%s\n", dentry,
             dentry->d_name.len, dentry->d_name.name, di->offset,
             filp->f_pos, d_unhashed(dentry) ? " unhashed" : "",
             !dentry->d_inode ? " null" : "");
        spin_unlock(&dentry->d_lock);
        p = p->prev;
        dentry = list_entry(p, struct dentry, d_u.d_child);
        di = ceph_dentry(dentry);
    }

    dget_dlock(dentry);
    spin_unlock(&dentry->d_lock);
    spin_unlock(&parent->d_lock);

    dout(" %llu (%llu) dentry %p %.*s %p\n", di->offset, filp->f_pos,
         dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
    filp->f_pos = di->offset;
    err = filldir(dirent, dentry->d_name.name,
              dentry->d_name.len, di->offset,
              ceph_translate_ino(dentry->d_sb, dentry->d_inode->i_ino),
              dentry->d_inode->i_mode >> 12);

    if (last) {
        if (err < 0) {
            /* remember our position */
            fi->dentry = last;
            fi->next_offset = di->offset;
        } else {
            dput(last);
        }
    }
    last = dentry;

    if (err < 0)
        goto out;

    filp->f_pos++;

    /* make sure a dentry wasn't dropped while we didn't have parent lock */
    if (!ceph_dir_test_complete(dir)) {
        dout(" lost D_COMPLETE on %p; falling back to mds\n", dir);
        err = -EAGAIN;
        goto out;
    }

    spin_lock(&parent->d_lock);
    p = p->prev;    /* advance to next dentry */
    goto more;

out_unlock:
    spin_unlock(&parent->d_lock);
out:
    if (last)
        dput(last);
    return err;
}

/*
 * make note of the last dentry we read, so we can
 * continue at the same lexicographical point,
 * regardless of what dir changes take place on the
 * server.
 */
static int note_last_dentry(struct ceph_file_info *fi, const char *name,
                int len)
{
    kfree(fi->last_name);
    fi->last_name = kmalloc(len+1, GFP_NOFS);
    if (!fi->last_name)
        return -ENOMEM;
    memcpy(fi->last_name, name, len);
    fi->last_name[len] = 0;
    dout("note_last_dentry '%s'\n", fi->last_name);
    return 0;
}

static int ceph_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
    struct ceph_file_info *fi = filp->private_data;
    struct inode *inode = filp->f_dentry->d_inode;
    struct ceph_inode_info *ci = ceph_inode(inode);
    struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    unsigned frag = fpos_frag(filp->f_pos);
    int off = fpos_off(filp->f_pos);
    int err;
    u32 ftype;
    struct ceph_mds_reply_info_parsed *rinfo;
    const int max_entries = fsc->mount_options->max_readdir;
    const int max_bytes = fsc->mount_options->max_readdir_bytes;

    dout("readdir %p filp %p frag %u off %u\n", inode, filp, frag, off);
    if (fi->flags & CEPH_F_ATEND)
        return 0;

    /* always start with . and .. */
    if (filp->f_pos == 0) {
        /* note dir version at start of readdir so we can tell
         * if any dentries get dropped */
        fi->dir_release_count = ci->i_release_count;

        dout("readdir off 0 -> '.'\n");
        if (filldir(dirent, ".", 1, ceph_make_fpos(0, 0),
                ceph_translate_ino(inode->i_sb, inode->i_ino),
                inode->i_mode >> 12) < 0)
            return 0;
        filp->f_pos = 1;
        off = 1;
    }
    if (filp->f_pos == 1) {
        ino_t ino = parent_ino(filp->f_dentry);
        dout("readdir off 1 -> '..'\n");
        if (filldir(dirent, "..", 2, ceph_make_fpos(0, 1),
                ceph_translate_ino(inode->i_sb, ino),
                inode->i_mode >> 12) < 0)
            return 0;
        filp->f_pos = 2;
        off = 2;
    }

    /* can we use the dcache? */
    spin_lock(&ci->i_ceph_lock);
    if ((filp->f_pos == 2 || fi->dentry) &&
        !ceph_test_mount_opt(fsc, NOASYNCREADDIR) &&
        ceph_snap(inode) != CEPH_SNAPDIR &&
        ceph_dir_test_complete(inode) &&
        __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1)) {
        spin_unlock(&ci->i_ceph_lock);
        err = __dcache_readdir(filp, dirent, filldir);
        if (err != -EAGAIN)
            return err;
    } else {
        spin_unlock(&ci->i_ceph_lock);
    }
    if (fi->dentry) {
        err = note_last_dentry(fi, fi->dentry->d_name.name,
                       fi->dentry->d_name.len);
        if (err)
            return err;
        dput(fi->dentry);
        fi->dentry = NULL;
    }

    /* proceed with a normal readdir */

more:
    /* do we have the correct frag content buffered? */
    if (fi->frag != frag || fi->last_readdir == NULL) {
        struct ceph_mds_request *req;
        int op = ceph_snap(inode) == CEPH_SNAPDIR ?
            CEPH_MDS_OP_LSSNAP : CEPH_MDS_OP_READDIR;

        /* discard old result, if any */
        if (fi->last_readdir) {
            ceph_mdsc_put_request(fi->last_readdir);
            fi->last_readdir = NULL;
        }

        /* requery frag tree, as the frag topology may have changed */
        frag = ceph_choose_frag(ceph_inode(inode), frag, NULL, NULL);

        dout("readdir fetching %llx.%llx frag %x offset '%s'\n",
             ceph_vinop(inode), frag, fi->last_name);
        req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
        if (IS_ERR(req))
            return PTR_ERR(req);
        req->r_inode = inode;
        ihold(inode);
        req->r_dentry = dget(filp->f_dentry);
        /* hints to request -> mds selection code */
        req->r_direct_mode = USE_AUTH_MDS;
        req->r_direct_hash = ceph_frag_value(frag);
        req->r_direct_is_hash = true;
        req->r_path2 = kstrdup(fi->last_name, GFP_NOFS);
        req->r_readdir_offset = fi->next_offset;
        req->r_args.readdir.frag = cpu_to_le32(frag);
        req->r_args.readdir.max_entries = cpu_to_le32(max_entries);
        req->r_args.readdir.max_bytes = cpu_to_le32(max_bytes);
        req->r_num_caps = max_entries + 1;
        err = ceph_mdsc_do_request(mdsc, NULL, req);
        if (err < 0) {
            ceph_mdsc_put_request(req);
            return err;
        }
        dout("readdir got and parsed readdir result=%d"
             " on frag %x, end=%d, complete=%d\n", err, frag,
             (int)req->r_reply_info.dir_end,
             (int)req->r_reply_info.dir_complete);

        if (!req->r_did_prepopulate) {
            dout("readdir !did_prepopulate");
            fi->dir_release_count--;    /* preclude D_COMPLETE */
        }

        /* note next offset and last dentry name */
        fi->offset = fi->next_offset;
        fi->last_readdir = req;

        if (req->r_reply_info.dir_end) {
            kfree(fi->last_name);
            fi->last_name = NULL;
            if (ceph_frag_is_rightmost(frag))
                fi->next_offset = 2;
            else
                fi->next_offset = 0;
        } else {
            rinfo = &req->r_reply_info;
            err = note_last_dentry(fi,
                       rinfo->dir_dname[rinfo->dir_nr-1],
                       rinfo->dir_dname_len[rinfo->dir_nr-1]);
            if (err)
                return err;
            fi->next_offset += rinfo->dir_nr;
        }
    }

    rinfo = &fi->last_readdir->r_reply_info;
    dout("readdir frag %x num %d off %d chunkoff %d\n", frag,
         rinfo->dir_nr, off, fi->offset);
    while (off >= fi->offset && off - fi->offset < rinfo->dir_nr) {
        u64 pos = ceph_make_fpos(frag, off);
        struct ceph_mds_reply_inode *in =
            rinfo->dir_in[off - fi->offset].in;
        struct ceph_vino vino;
        ino_t ino;

        dout("readdir off %d (%d/%d) -> %lld '%.*s' %p\n",
             off, off - fi->offset, rinfo->dir_nr, pos,
             rinfo->dir_dname_len[off - fi->offset],
             rinfo->dir_dname[off - fi->offset], in);
        BUG_ON(!in);
        ftype = le32_to_cpu(in->mode) >> 12;
        vino.ino = le64_to_cpu(in->ino);
        vino.snap = le64_to_cpu(in->snapid);
        ino = ceph_vino_to_ino(vino);
        if (filldir(dirent,
                rinfo->dir_dname[off - fi->offset],
                rinfo->dir_dname_len[off - fi->offset],
                pos,
                ceph_translate_ino(inode->i_sb, ino), ftype) < 0) {
            dout("filldir stopping us...\n");
            return 0;
        }
        off++;
        filp->f_pos = pos + 1;
    }

    if (fi->last_name) {
        ceph_mdsc_put_request(fi->last_readdir);
        fi->last_readdir = NULL;
        goto more;
    }

    /* more frags? */
    if (!ceph_frag_is_rightmost(frag)) {
        frag = ceph_frag_next(frag);
        off = 0;
        filp->f_pos = ceph_make_fpos(frag, off);
        dout("readdir next frag is %x\n", frag);
        goto more;
    }
    fi->flags |= CEPH_F_ATEND;

    /*
     * if dir_release_count still matches the dir, no dentries
     * were released during the whole readdir, and we should have
     * the complete dir contents in our cache.
     */
    spin_lock(&ci->i_ceph_lock);
    if (ci->i_release_count == fi->dir_release_count) {
        ceph_dir_set_complete(inode);
        ci->i_max_offset = filp->f_pos;
    }
    spin_unlock(&ci->i_ceph_lock);

    dout("readdir %p filp %p done.\n", inode, filp);
    return 0;
}

static void reset_readdir(struct ceph_file_info *fi)
{
    if (fi->last_readdir) {
        ceph_mdsc_put_request(fi->last_readdir);
        fi->last_readdir = NULL;
    }
    kfree(fi->last_name);
    fi->last_name = NULL;
    fi->next_offset = 2;  /* compensate for . and .. */
    if (fi->dentry) {
        dput(fi->dentry);
        fi->dentry = NULL;
    }
    fi->flags &= ~CEPH_F_ATEND;
}

static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int origin)
{
    struct ceph_file_info *fi = file->private_data;
    struct inode *inode = file->f_mapping->host;
    loff_t old_offset = offset;
    loff_t retval;

    mutex_lock(&inode->i_mutex);
    retval = -EINVAL;
    switch (origin) {
    case SEEK_END:
        offset += inode->i_size + 2;   /* FIXME */
        break;
    case SEEK_CUR:
        offset += file->f_pos;
    case SEEK_SET:
        break;
    default:
        goto out;
    }

    if (offset >= 0 && offset <= inode->i_sb->s_maxbytes) {
        if (offset != file->f_pos) {
            file->f_pos = offset;
            file->f_version = 0;
            fi->flags &= ~CEPH_F_ATEND;
        }
        retval = offset;

        /*
         * discard buffered readdir content on seekdir(0), or
         * seek to new frag, or seek prior to current chunk.
         */
        if (offset == 0 ||
            fpos_frag(offset) != fpos_frag(old_offset) ||
            fpos_off(offset) < fi->offset) {
            dout("dir_llseek dropping %p content\n", file);
            reset_readdir(fi);
        }

        /* bump dir_release_count if we did a forward seek */
        if (offset > old_offset)
            fi->dir_release_count--;
    }
out:
    mutex_unlock(&inode->i_mutex);
    return retval;
}

/*
 * Handle lookups for the hidden .snap directory.
 */
int ceph_handle_snapdir(struct ceph_mds_request *req,
            struct dentry *dentry, int err)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb);
    struct inode *parent = dentry->d_parent->d_inode; /* we hold i_mutex */

    /* .snap dir? */
    if (err == -ENOENT &&
        ceph_snap(parent) == CEPH_NOSNAP &&
        strcmp(dentry->d_name.name,
           fsc->mount_options->snapdir_name) == 0) {
        struct inode *inode = ceph_get_snapdir(parent);
        dout("ENOENT on snapdir %p '%.*s', linking to snapdir %p\n",
             dentry, dentry->d_name.len, dentry->d_name.name, inode);
        BUG_ON(!d_unhashed(dentry));
        d_add(dentry, inode);
        err = 0;
    }
    return err;
}

/*
 * Figure out final result of a lookup/open request.
 *
 * Mainly, make sure we return the final req->r_dentry (if it already
 * existed) in place of the original VFS-provided dentry when they
 * differ.
 *
 * Gracefully handle the case where the MDS replies with -ENOENT and
 * no trace (which it may do, at its discretion, e.g., if it doesn't
 * care to issue a lease on the negative dentry).
 */
struct dentry *ceph_finish_lookup(struct ceph_mds_request *req,
                  struct dentry *dentry, int err)
{
    if (err == -ENOENT) {
        /* no trace? */
        err = 0;
        if (!req->r_reply_info.head->is_dentry) {
            dout("ENOENT and no trace, dentry %p inode %p\n",
                 dentry, dentry->d_inode);
            if (dentry->d_inode) {
                d_drop(dentry);
                err = -ENOENT;
            } else {
                d_add(dentry, NULL);
            }
        }
    }
    if (err)
        dentry = ERR_PTR(err);
    else if (dentry != req->r_dentry)
        dentry = dget(req->r_dentry);   /* we got spliced */
    else
        dentry = NULL;
    return dentry;
}

static int is_root_ceph_dentry(struct inode *inode, struct dentry *dentry)
{
    return ceph_ino(inode) == CEPH_INO_ROOT &&
        strncmp(dentry->d_name.name, ".ceph", 5) == 0;
}

/*
 * Look up a single dir entry.  If there is a lookup intent, inform
 * the MDS so that it gets our 'caps wanted' value in a single op.
 */
static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
                  unsigned int flags)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct ceph_mds_request *req;
    int op;
    int err;

    dout("lookup %p dentry %p '%.*s'\n",
         dir, dentry, dentry->d_name.len, dentry->d_name.name);

    if (dentry->d_name.len > NAME_MAX)
        return ERR_PTR(-ENAMETOOLONG);

    err = ceph_init_dentry(dentry);
    if (err < 0)
        return ERR_PTR(err);

    /* can we conclude ENOENT locally? */
    if (dentry->d_inode == NULL) {
        struct ceph_inode_info *ci = ceph_inode(dir);
        struct ceph_dentry_info *di = ceph_dentry(dentry);

        spin_lock(&ci->i_ceph_lock);
        dout(" dir %p flags are %d\n", dir, ci->i_ceph_flags);
        if (strncmp(dentry->d_name.name,
                fsc->mount_options->snapdir_name,
                dentry->d_name.len) &&
            !is_root_ceph_dentry(dir, dentry) &&
            ceph_dir_test_complete(dir) &&
            (__ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1))) {
            spin_unlock(&ci->i_ceph_lock);
            dout(" dir %p complete, -ENOENT\n", dir);
            d_add(dentry, NULL);
            di->lease_shared_gen = ci->i_shared_gen;
            return NULL;
        }
        spin_unlock(&ci->i_ceph_lock);
    }

    op = ceph_snap(dir) == CEPH_SNAPDIR ?
        CEPH_MDS_OP_LOOKUPSNAP : CEPH_MDS_OP_LOOKUP;
    req = ceph_mdsc_create_request(mdsc, op, USE_ANY_MDS);
    if (IS_ERR(req))
        return ERR_CAST(req);
    req->r_dentry = dget(dentry);
    req->r_num_caps = 2;
    /* we only need inode linkage */
    req->r_args.getattr.mask = cpu_to_le32(CEPH_STAT_CAP_INODE);
    req->r_locked_dir = dir;
    err = ceph_mdsc_do_request(mdsc, NULL, req);
    err = ceph_handle_snapdir(req, dentry, err);
    dentry = ceph_finish_lookup(req, dentry, err);
    ceph_mdsc_put_request(req);  /* will dput(dentry) */
    dout("lookup result=%p\n", dentry);
    return dentry;
}

/*
 * If we do a create but get no trace back from the MDS, follow up with
 * a lookup (the VFS expects us to link up the provided dentry).
 */
int ceph_handle_notrace_create(struct inode *dir, struct dentry *dentry)
{
    struct dentry *result = ceph_lookup(dir, dentry, 0);

    if (result && !IS_ERR(result)) {
        /*
         * We created the item, then did a lookup, and found
         * it was already linked to another inode we already
         * had in our cache (and thus got spliced).  Link our
         * dentry to that inode, but don't hash it, just in
         * case the VFS wants to dereference it.
         */
        BUG_ON(!result->d_inode);
        d_instantiate(dentry, result->d_inode);
        return 0;
    }
    return PTR_ERR(result);
}

static int ceph_mknod(struct inode *dir, struct dentry *dentry,
              umode_t mode, dev_t rdev)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct ceph_mds_request *req;
    int err;

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

    dout("mknod in dir %p dentry %p mode 0%ho rdev %d\n",
         dir, dentry, mode, rdev);
    req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_MKNOD, USE_AUTH_MDS);
    if (IS_ERR(req)) {
        d_drop(dentry);
        return PTR_ERR(req);
    }
    req->r_dentry = dget(dentry);
    req->r_num_caps = 2;
    req->r_locked_dir = dir;
    req->r_args.mknod.mode = cpu_to_le32(mode);
    req->r_args.mknod.rdev = cpu_to_le32(rdev);
    req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
    req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
    err = ceph_mdsc_do_request(mdsc, dir, req);
    if (!err && !req->r_reply_info.head->is_dentry)
        err = ceph_handle_notrace_create(dir, dentry);
    ceph_mdsc_put_request(req);
    if (err)
        d_drop(dentry);
    return err;
}

static int ceph_create(struct inode *dir, struct dentry *dentry, umode_t mode,
               bool excl)
{
    return ceph_mknod(dir, dentry, mode, 0);
}

static int ceph_symlink(struct inode *dir, struct dentry *dentry,
                const char *dest)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct ceph_mds_request *req;
    int err;

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

    dout("symlink in dir %p dentry %p to '%s'\n", dir, dentry, dest);
    req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SYMLINK, USE_AUTH_MDS);
    if (IS_ERR(req)) {
        d_drop(dentry);
        return PTR_ERR(req);
    }
    req->r_dentry = dget(dentry);
    req->r_num_caps = 2;
    req->r_path2 = kstrdup(dest, GFP_NOFS);
    req->r_locked_dir = dir;
    req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
    req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
    err = ceph_mdsc_do_request(mdsc, dir, req);
    if (!err && !req->r_reply_info.head->is_dentry)
        err = ceph_handle_notrace_create(dir, dentry);
    ceph_mdsc_put_request(req);
    if (err)
        d_drop(dentry);
    return err;
}

static int ceph_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct ceph_mds_request *req;
    int err = -EROFS;
    int op;

    if (ceph_snap(dir) == CEPH_SNAPDIR) {
        /* mkdir .snap/foo is a MKSNAP */
        op = CEPH_MDS_OP_MKSNAP;
        dout("mksnap dir %p snap '%.*s' dn %p\n", dir,
             dentry->d_name.len, dentry->d_name.name, dentry);
    } else if (ceph_snap(dir) == CEPH_NOSNAP) {
        dout("mkdir dir %p dn %p mode 0%ho\n", dir, dentry, mode);
        op = CEPH_MDS_OP_MKDIR;
    } else {
        goto out;
    }
    req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
    if (IS_ERR(req)) {
        err = PTR_ERR(req);
        goto out;
    }

    req->r_dentry = dget(dentry);
    req->r_num_caps = 2;
    req->r_locked_dir = dir;
    req->r_args.mkdir.mode = cpu_to_le32(mode);
    req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
    req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
    err = ceph_mdsc_do_request(mdsc, dir, req);
    if (!err && !req->r_reply_info.head->is_dentry)
        err = ceph_handle_notrace_create(dir, dentry);
    ceph_mdsc_put_request(req);
out:
    if (err < 0)
        d_drop(dentry);
    return err;
}

static int ceph_link(struct dentry *old_dentry, struct inode *dir,
             struct dentry *dentry)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct ceph_mds_request *req;
    int err;

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

    dout("link in dir %p old_dentry %p dentry %p\n", dir,
         old_dentry, dentry);
    req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LINK, USE_AUTH_MDS);
    if (IS_ERR(req)) {
        d_drop(dentry);
        return PTR_ERR(req);
    }
    req->r_dentry = dget(dentry);
    req->r_num_caps = 2;
    req->r_old_dentry = dget(old_dentry); /* or inode? hrm. */
    req->r_old_dentry_dir = ceph_get_dentry_parent_inode(old_dentry);
    req->r_locked_dir = dir;
    req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
    req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
    err = ceph_mdsc_do_request(mdsc, dir, req);
    if (err) {
        d_drop(dentry);
    } else if (!req->r_reply_info.head->is_dentry) {
        ihold(old_dentry->d_inode);
        d_instantiate(dentry, old_dentry->d_inode);
    }
    ceph_mdsc_put_request(req);
    return err;
}

/*
 * For a soon-to-be unlinked file, drop the AUTH_RDCACHE caps.  If it
 * looks like the link count will hit 0, drop any other caps (other
 * than PIN) we don't specifically want (due to the file still being
 * open).
 */
static int drop_caps_for_unlink(struct inode *inode)
{
    struct ceph_inode_info *ci = ceph_inode(inode);
    int drop = CEPH_CAP_LINK_SHARED | CEPH_CAP_LINK_EXCL;

    spin_lock(&ci->i_ceph_lock);
    if (inode->i_nlink == 1) {
        drop |= ~(__ceph_caps_wanted(ci) | CEPH_CAP_PIN);
        ci->i_ceph_flags |= CEPH_I_NODELAY;
    }
    spin_unlock(&ci->i_ceph_lock);
    return drop;
}

/*
 * rmdir and unlink are differ only by the metadata op code
 */
static int ceph_unlink(struct inode *dir, struct dentry *dentry)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct inode *inode = dentry->d_inode;
    struct ceph_mds_request *req;
    int err = -EROFS;
    int op;

    if (ceph_snap(dir) == CEPH_SNAPDIR) {
        /* rmdir .snap/foo is RMSNAP */
        dout("rmsnap dir %p '%.*s' dn %p\n", dir, dentry->d_name.len,
             dentry->d_name.name, dentry);
        op = CEPH_MDS_OP_RMSNAP;
    } else if (ceph_snap(dir) == CEPH_NOSNAP) {
        dout("unlink/rmdir dir %p dn %p inode %p\n",
             dir, dentry, inode);
        op = S_ISDIR(dentry->d_inode->i_mode) ?
            CEPH_MDS_OP_RMDIR : CEPH_MDS_OP_UNLINK;
    } else
        goto out;
    req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
    if (IS_ERR(req)) {
        err = PTR_ERR(req);
        goto out;
    }
    req->r_dentry = dget(dentry);
    req->r_num_caps = 2;
    req->r_locked_dir = dir;
    req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
    req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
    req->r_inode_drop = drop_caps_for_unlink(inode);
    err = ceph_mdsc_do_request(mdsc, dir, req);
    if (!err && !req->r_reply_info.head->is_dentry)
        d_delete(dentry);
    ceph_mdsc_put_request(req);
out:
    return err;
}

static int ceph_rename(struct inode *old_dir, struct dentry *old_dentry,
               struct inode *new_dir, struct dentry *new_dentry)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(old_dir->i_sb);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct ceph_mds_request *req;
    int err;

    if (ceph_snap(old_dir) != ceph_snap(new_dir))
        return -EXDEV;
    if (ceph_snap(old_dir) != CEPH_NOSNAP ||
        ceph_snap(new_dir) != CEPH_NOSNAP)
        return -EROFS;
    dout("rename dir %p dentry %p to dir %p dentry %p\n",
         old_dir, old_dentry, new_dir, new_dentry);
    req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_RENAME, USE_AUTH_MDS);
    if (IS_ERR(req))
        return PTR_ERR(req);
    req->r_dentry = dget(new_dentry);
    req->r_num_caps = 2;
    req->r_old_dentry = dget(old_dentry);
    req->r_old_dentry_dir = ceph_get_dentry_parent_inode(old_dentry);
    req->r_locked_dir = new_dir;
    req->r_old_dentry_drop = CEPH_CAP_FILE_SHARED;
    req->r_old_dentry_unless = CEPH_CAP_FILE_EXCL;
    req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
    req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
    /* release LINK_RDCACHE on source inode (mds will lock it) */
    req->r_old_inode_drop = CEPH_CAP_LINK_SHARED;
    if (new_dentry->d_inode)
        req->r_inode_drop = drop_caps_for_unlink(new_dentry->d_inode);
    err = ceph_mdsc_do_request(mdsc, old_dir, req);
    if (!err && !req->r_reply_info.head->is_dentry) {
        /*
         * Normally d_move() is done by fill_trace (called by
         * do_request, above).  If there is no trace, we need
         * to do it here.
         */

        /* d_move screws up d_subdirs order */
        ceph_dir_clear_complete(new_dir);

        d_move(old_dentry, new_dentry);

        /* ensure target dentry is invalidated, despite
           rehashing bug in vfs_rename_dir */
        ceph_invalidate_dentry_lease(new_dentry);
    }
    ceph_mdsc_put_request(req);
    return err;
}

/*
 * Ensure a dentry lease will no longer revalidate.
 */
void ceph_invalidate_dentry_lease(struct dentry *dentry)
{
    spin_lock(&dentry->d_lock);
    dentry->d_time = jiffies;
    ceph_dentry(dentry)->lease_shared_gen = 0;
    spin_unlock(&dentry->d_lock);
}

/*
 * Check if dentry lease is valid.  If not, delete the lease.  Try to
 * renew if the least is more than half up.
 */
static int dentry_lease_is_valid(struct dentry *dentry)
{
    struct ceph_dentry_info *di;
    struct ceph_mds_session *s;
    int valid = 0;
    u32 gen;
    unsigned long ttl;
    struct ceph_mds_session *session = NULL;
    struct inode *dir = NULL;
    u32 seq = 0;

    spin_lock(&dentry->d_lock);
    di = ceph_dentry(dentry);
    if (di->lease_session) {
        s = di->lease_session;
        spin_lock(&s->s_gen_ttl_lock);
        gen = s->s_cap_gen;
        ttl = s->s_cap_ttl;
        spin_unlock(&s->s_gen_ttl_lock);

        if (di->lease_gen == gen &&
            time_before(jiffies, dentry->d_time) &&
            time_before(jiffies, ttl)) {
            valid = 1;
            if (di->lease_renew_after &&
                time_after(jiffies, di->lease_renew_after)) {
                /* we should renew */
                dir = dentry->d_parent->d_inode;
                session = ceph_get_mds_session(s);
                seq = di->lease_seq;
                di->lease_renew_after = 0;
                di->lease_renew_from = jiffies;
            }
        }
    }
    spin_unlock(&dentry->d_lock);

    if (session) {
        ceph_mdsc_lease_send_msg(session, dir, dentry,
                     CEPH_MDS_LEASE_RENEW, seq);
        ceph_put_mds_session(session);
    }
    dout("dentry_lease_is_valid - dentry %p = %d\n", dentry, valid);
    return valid;
}

/*
 * Check if directory-wide content lease/cap is valid.
 */
static int dir_lease_is_valid(struct inode *dir, struct dentry *dentry)
{
    struct ceph_inode_info *ci = ceph_inode(dir);
    struct ceph_dentry_info *di = ceph_dentry(dentry);
    int valid = 0;

    spin_lock(&ci->i_ceph_lock);
    if (ci->i_shared_gen == di->lease_shared_gen)
        valid = __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1);
    spin_unlock(&ci->i_ceph_lock);
    dout("dir_lease_is_valid dir %p v%u dentry %p v%u = %d\n",
         dir, (unsigned)ci->i_shared_gen, dentry,
         (unsigned)di->lease_shared_gen, valid);
    return valid;
}

/*
 * Check if cached dentry can be trusted.
 */
static int ceph_d_revalidate(struct dentry *dentry, unsigned int flags)
{
    int valid = 0;
    struct inode *dir;

    if (flags & LOOKUP_RCU)
        return -ECHILD;

    dout("d_revalidate %p '%.*s' inode %p offset %lld\n", dentry,
         dentry->d_name.len, dentry->d_name.name, dentry->d_inode,
         ceph_dentry(dentry)->offset);

    dir = ceph_get_dentry_parent_inode(dentry);

    /* always trust cached snapped dentries, snapdir dentry */
    if (ceph_snap(dir) != CEPH_NOSNAP) {
        dout("d_revalidate %p '%.*s' inode %p is SNAPPED\n", dentry,
             dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
        valid = 1;
    } else if (dentry->d_inode &&
           ceph_snap(dentry->d_inode) == CEPH_SNAPDIR) {
        valid = 1;
    } else if (dentry_lease_is_valid(dentry) ||
           dir_lease_is_valid(dir, dentry)) {
        valid = 1;
    }

    dout("d_revalidate %p %s\n", dentry, valid ? "valid" : "invalid");
    if (valid)
        ceph_dentry_lru_touch(dentry);
    else
        d_drop(dentry);
    iput(dir);
    return valid;
}

/*
 * Release our ceph_dentry_info.
 */
static void ceph_d_release(struct dentry *dentry)
{
    struct ceph_dentry_info *di = ceph_dentry(dentry);

    dout("d_release %p\n", dentry);
    ceph_dentry_lru_del(dentry);
    if (di->lease_session)
        ceph_put_mds_session(di->lease_session);
    kmem_cache_free(ceph_dentry_cachep, di);
    dentry->d_fsdata = NULL;
}

static int ceph_snapdir_d_revalidate(struct dentry *dentry,
                      unsigned int flags)
{
    /*
     * Eventually, we'll want to revalidate snapped metadata
     * too... probably...
     */
    return 1;
}

/*
 * Set/clear/test dir complete flag on the dir's dentry.
 */
void ceph_dir_set_complete(struct inode *inode)
{
    struct dentry *dentry = d_find_any_alias(inode);
    
    if (dentry && ceph_dentry(dentry) &&
        ceph_test_mount_opt(ceph_sb_to_client(dentry->d_sb), DCACHE)) {
        dout(" marking %p (%p) complete\n", inode, dentry);
        set_bit(CEPH_D_COMPLETE, &ceph_dentry(dentry)->flags);
    }
    dput(dentry);
}

void ceph_dir_clear_complete(struct inode *inode)
{
    struct dentry *dentry = d_find_any_alias(inode);

    if (dentry && ceph_dentry(dentry)) {
        dout(" marking %p (%p) complete\n", inode, dentry);
        set_bit(CEPH_D_COMPLETE, &ceph_dentry(dentry)->flags);
    }
    dput(dentry);
}

bool ceph_dir_test_complete(struct inode *inode)
{
    struct dentry *dentry = d_find_any_alias(inode);

    if (dentry && ceph_dentry(dentry)) {
        dout(" marking %p (%p) NOT complete\n", inode, dentry);
        clear_bit(CEPH_D_COMPLETE, &ceph_dentry(dentry)->flags);
    }
    dput(dentry);
    return false;
}

/*
 * When the VFS prunes a dentry from the cache, we need to clear the
 * complete flag on the parent directory.
 *
 * Called under dentry->d_lock.
 */
static void ceph_d_prune(struct dentry *dentry)
{
    struct ceph_dentry_info *di;

    dout("ceph_d_prune %p\n", dentry);

    /* do we have a valid parent? */
    if (IS_ROOT(dentry))
        return;

    /* if we are not hashed, we don't affect D_COMPLETE */
    if (d_unhashed(dentry))
        return;

    /*
     * we hold d_lock, so d_parent is stable, and d_fsdata is never
     * cleared until d_release
     */
    di = ceph_dentry(dentry->d_parent);
    clear_bit(CEPH_D_COMPLETE, &di->flags);
}

/*
 * read() on a dir.  This weird interface hack only works if mounted
 * with '-o dirstat'.
 */
static ssize_t ceph_read_dir(struct file *file, char __user *buf, size_t size,
                 loff_t *ppos)
{
    struct ceph_file_info *cf = file->private_data;
    struct inode *inode = file->f_dentry->d_inode;
    struct ceph_inode_info *ci = ceph_inode(inode);
    int left;
    const int bufsize = 1024;

    if (!ceph_test_mount_opt(ceph_sb_to_client(inode->i_sb), DIRSTAT))
        return -EISDIR;

    if (!cf->dir_info) {
        cf->dir_info = kmalloc(bufsize, GFP_NOFS);
        if (!cf->dir_info)
            return -ENOMEM;
        cf->dir_info_len =
            snprintf(cf->dir_info, bufsize,
                "entries:   %20lld\n"
                " files:    %20lld\n"
                " subdirs:  %20lld\n"
                "rentries:  %20lld\n"
                " rfiles:   %20lld\n"
                " rsubdirs: %20lld\n"
                "rbytes:    %20lld\n"
                "rctime:    %10ld.%09ld\n",
                ci->i_files + ci->i_subdirs,
                ci->i_files,
                ci->i_subdirs,
                ci->i_rfiles + ci->i_rsubdirs,
                ci->i_rfiles,
                ci->i_rsubdirs,
                ci->i_rbytes,
                (long)ci->i_rctime.tv_sec,
                (long)ci->i_rctime.tv_nsec);
    }

    if (*ppos >= cf->dir_info_len)
        return 0;
    size = min_t(unsigned, size, cf->dir_info_len-*ppos);
    left = copy_to_user(buf, cf->dir_info + *ppos, size);
    if (left == size)
        return -EFAULT;
    *ppos += (size - left);
    return size - left;
}

/*
 * an fsync() on a dir will wait for any uncommitted directory
 * operations to commit.
 */
static int ceph_dir_fsync(struct file *file, loff_t start, loff_t end,
              int datasync)
{
    struct inode *inode = file->f_path.dentry->d_inode;
    struct ceph_inode_info *ci = ceph_inode(inode);
    struct list_head *head = &ci->i_unsafe_dirops;
    struct ceph_mds_request *req;
    u64 last_tid;
    int ret = 0;

    dout("dir_fsync %p\n", inode);
    ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
    if (ret)
        return ret;
    mutex_lock(&inode->i_mutex);

    spin_lock(&ci->i_unsafe_lock);
    if (list_empty(head))
        goto out;

    req = list_entry(head->prev,
             struct ceph_mds_request, r_unsafe_dir_item);
    last_tid = req->r_tid;

    do {
        ceph_mdsc_get_request(req);
        spin_unlock(&ci->i_unsafe_lock);

        dout("dir_fsync %p wait on tid %llu (until %llu)\n",
             inode, req->r_tid, last_tid);
        if (req->r_timeout) {
            ret = wait_for_completion_timeout(
                &req->r_safe_completion, req->r_timeout);
            if (ret > 0)
                ret = 0;
            else if (ret == 0)
                ret = -EIO;  /* timed out */
        } else {
            wait_for_completion(&req->r_safe_completion);
        }
        ceph_mdsc_put_request(req);

        spin_lock(&ci->i_unsafe_lock);
        if (ret || list_empty(head))
            break;
        req = list_entry(head->next,
                 struct ceph_mds_request, r_unsafe_dir_item);
    } while (req->r_tid < last_tid);
out:
    spin_unlock(&ci->i_unsafe_lock);
    mutex_unlock(&inode->i_mutex);

    return ret;
}

/*
 * We maintain a private dentry LRU.
 *
 * FIXME: this needs to be changed to a per-mds lru to be useful.
 */
void ceph_dentry_lru_add(struct dentry *dn)
{
    struct ceph_dentry_info *di = ceph_dentry(dn);
    struct ceph_mds_client *mdsc;

    dout("dentry_lru_add %p %p '%.*s'\n", di, dn,
         dn->d_name.len, dn->d_name.name);
    mdsc = ceph_sb_to_client(dn->d_sb)->mdsc;
    spin_lock(&mdsc->dentry_lru_lock);
    list_add_tail(&di->lru, &mdsc->dentry_lru);
    mdsc->num_dentry++;
    spin_unlock(&mdsc->dentry_lru_lock);
}

void ceph_dentry_lru_touch(struct dentry *dn)
{
    struct ceph_dentry_info *di = ceph_dentry(dn);
    struct ceph_mds_client *mdsc;

    dout("dentry_lru_touch %p %p '%.*s' (offset %lld)\n", di, dn,
         dn->d_name.len, dn->d_name.name, di->offset);
    mdsc = ceph_sb_to_client(dn->d_sb)->mdsc;
    spin_lock(&mdsc->dentry_lru_lock);
    list_move_tail(&di->lru, &mdsc->dentry_lru);
    spin_unlock(&mdsc->dentry_lru_lock);
}

void ceph_dentry_lru_del(struct dentry *dn)
{
    struct ceph_dentry_info *di = ceph_dentry(dn);
    struct ceph_mds_client *mdsc;

    dout("dentry_lru_del %p %p '%.*s'\n", di, dn,
         dn->d_name.len, dn->d_name.name);
    mdsc = ceph_sb_to_client(dn->d_sb)->mdsc;
    spin_lock(&mdsc->dentry_lru_lock);
    list_del_init(&di->lru);
    mdsc->num_dentry--;
    spin_unlock(&mdsc->dentry_lru_lock);
}

/*
 * Return name hash for a given dentry.  This is dependent on
 * the parent directory's hash function.
 */
unsigned ceph_dentry_hash(struct inode *dir, struct dentry *dn)
{
    struct ceph_inode_info *dci = ceph_inode(dir);

    switch (dci->i_dir_layout.dl_dir_hash) {
    case 0: /* for backward compat */
    case CEPH_STR_HASH_LINUX:
        return dn->d_name.hash;

    default:
        return ceph_str_hash(dci->i_dir_layout.dl_dir_hash,
                     dn->d_name.name, dn->d_name.len);
    }
}

const struct file_operations ceph_dir_fops = {
    .read = ceph_read_dir,
    .readdir = ceph_readdir,
    .llseek = ceph_dir_llseek,
    .open = ceph_open,
    .release = ceph_release,
    .unlocked_ioctl = ceph_ioctl,
    .fsync = ceph_dir_fsync,
};

const struct inode_operations ceph_dir_iops = {
    .lookup = ceph_lookup,
    .permission = ceph_permission,
    .getattr = ceph_getattr,
    .setattr = ceph_setattr,
    .setxattr = ceph_setxattr,
    .getxattr = ceph_getxattr,
    .listxattr = ceph_listxattr,
    .removexattr = ceph_removexattr,
    .mknod = ceph_mknod,
    .symlink = ceph_symlink,
    .mkdir = ceph_mkdir,
    .link = ceph_link,
    .unlink = ceph_unlink,
    .rmdir = ceph_unlink,
    .rename = ceph_rename,
    .create = ceph_create,
    .atomic_open = ceph_atomic_open,
};

const struct dentry_operations ceph_dentry_ops = {
    .d_revalidate = ceph_d_revalidate,
    .d_release = ceph_d_release,
    .d_prune = ceph_d_prune,
};

const struct dentry_operations ceph_snapdir_dentry_ops = {
    .d_revalidate = ceph_snapdir_d_revalidate,
    .d_release = ceph_d_release,
};

const struct dentry_operations ceph_snap_dentry_ops = {
    .d_release = ceph_d_release,
    .d_prune = ceph_d_prune,
};