loader: ptable_close should check for NULL argument

[unleashed.git] / kernel / fs / gfs.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/* Portions Copyright 2007 Shivakumar GN */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright (c) 2017 by Delphix. All rights reserved.
 */

#include <sys/types.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/dirent.h>
#include <sys/kmem.h>
#include <sys/mman.h>
#include <sys/mutex.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/sunddi.h>
#include <sys/uio.h>
#include <sys/vmsystm.h>
#include <sys/vfs.h>
#include <sys/vnode.h>

#include <vm/as.h>
#include <vm/seg_vn.h>

#include <sys/gfs.h>

/*
 * Generic pseudo-filesystem routines.
 *
 * There are significant similarities between the implementation of certain file
 * system entry points across different filesystems.  While one could attempt to
 * "choke up on the bat" and incorporate common functionality into a VOP
 * preamble or postamble, such an approach is limited in the benefit it can
 * provide.  In this file we instead define a toolkit of routines which can be
 * called from a filesystem (with in-kernel pseudo-filesystems being the focus
 * of the exercise) in a more component-like fashion.
 *
 * There are three basic classes of routines:
 *
 * 1) Lowlevel support routines
 *
 *    These routines are designed to play a support role for existing
 *    pseudo-filesystems (such as procfs).  They simplify common tasks,
 *    without forcing the filesystem to hand over management to GFS.  The
 *    routines covered are:
 *
 *      gfs_readdir_init()
 *      gfs_readdir_emit()
 *      gfs_readdir_emitn()
 *      gfs_readdir_pred()
 *      gfs_readdir_fini()
 *      gfs_lookup_dot()
 *
 * 2) Complete GFS management
 *
 *    These routines take a more active role in management of the
 *    pseudo-filesystem.  They handle the relationship between vnode private
 *    data and VFS data, as well as the relationship between vnodes in the
 *    directory hierarchy.
 *
 *    In order to use these interfaces, the first member of every private
 *    v_data must be a gfs_file_t or a gfs_dir_t.  This hands over all control
 *    to GFS.
 *
 *      gfs_file_create()
 *      gfs_dir_create()
 *      gfs_root_create()
 *
 *      gfs_file_inactive()
 *      gfs_dir_inactive()
 *      gfs_dir_lookup()
 *      gfs_dir_readdir()
 *
 *      gfs_vop_inactive()
 *      gfs_vop_lookup()
 *      gfs_vop_readdir()
 *      gfs_vop_map()
 *
 * 3) Single File pseudo-filesystems
 *
 *    This routine creates a rooted file to be overlayed ontop of another
 *    file in the physical filespace.
 *
 *    Note that the parent is NULL (actually the vfs), but there is nothing
 *    technically keeping such a file from utilizing the "Complete GFS
 *    management" set of routines.
 *
 *      gfs_root_create_file()
 */

/*
 * Low level directory routines
 *
 * These routines provide some simple abstractions for reading directories.
 * They are designed to be used by existing pseudo filesystems (namely procfs)
 * that already have a complicated management infrastructure.
 */

/*
 * gfs_get_parent_ino: used to obtain a parent inode number and the
 * inode number of the given vnode in preparation for calling gfs_readdir_init.
 */
int
gfs_get_parent_ino(vnode_t *dvp, cred_t *cr, caller_context_t *ct,
    ino64_t *pino, ino64_t *ino)
{
        vnode_t *parent;
        gfs_dir_t *dp = dvp->v_data;
        int error;

        *ino = dp->gfsd_file.gfs_ino;
        parent = dp->gfsd_file.gfs_parent;

        if (parent == NULL) {
                *pino = *ino;           /* root of filesystem */
        } else if (dvp->v_flag & V_XATTRDIR) {
                vattr_t va;

                va.va_mask = AT_NODEID;
                error = fop_getattr(parent, &va, 0, cr, ct);
                if (error)
                        return (error);
                *pino = va.va_nodeid;
        } else {
                *pino = ((gfs_file_t *)(parent->v_data))->gfs_ino;
        }

        return (0);
}

/*
 * gfs_readdir_init: initiate a generic readdir
 *   st         - a pointer to an uninitialized gfs_readdir_state_t structure
 *   name_max   - the directory's maximum file name length
 *   ureclen    - the exported file-space record length (1 for non-legacy FSs)
 *   uiop       - the uiop passed to readdir
 *   parent     - the parent directory's inode
 *   self       - this directory's inode
 *   flags      - flags from fop_readdir
 *
 * Returns 0 or a non-zero errno.
 *
 * Typical fop_readdir usage of gfs_readdir_*:
 *
 *      if ((error = gfs_readdir_init(...)) != 0)
 *              return (error);
 *      eof = 0;
 *      while ((error = gfs_readdir_pred(..., &voffset)) != 0) {
 *              if (!consumer_entry_at(voffset))
 *                      voffset = consumer_next_entry(voffset);
 *              if (consumer_eof(voffset)) {
 *                      eof = 1
 *                      break;
 *              }
 *              if ((error = gfs_readdir_emit(..., voffset,
 *                  consumer_ino(voffset), consumer_name(voffset))) != 0)
 *                      break;
 *      }
 *      return (gfs_readdir_fini(..., error, eofp, eof));
 *
 * As you can see, a zero result from gfs_readdir_pred() or
 * gfs_readdir_emit() indicates that processing should continue,
 * whereas a non-zero result indicates that the loop should terminate.
 * Most consumers need do nothing more than let gfs_readdir_fini()
 * determine what the cause of failure was and return the appropriate
 * value.
 */
int
gfs_readdir_init(gfs_readdir_state_t *st, int name_max, int ureclen,
    uio_t *uiop, ino64_t parent, ino64_t self, int flags)
{
        size_t dirent_size;

        if (uiop->uio_loffset < 0 || uiop->uio_resid <= 0 ||
            (uiop->uio_loffset % ureclen) != 0)
                return (EINVAL);

        st->grd_ureclen = ureclen;
        st->grd_oresid = uiop->uio_resid;
        st->grd_namlen = name_max;
        if (flags & V_RDDIR_ENTFLAGS)
                dirent_size = EDIRENT_RECLEN(st->grd_namlen);
        else
                dirent_size = DIRENT64_RECLEN(st->grd_namlen);
        st->grd_dirent = kmem_zalloc(dirent_size, KM_SLEEP);
        st->grd_parent = parent;
        st->grd_self = self;
        st->grd_flags = flags;

        return (0);
}

/*
 * gfs_readdir_emit_int: internal routine to emit directory entry
 *
 *   st         - the current readdir state, which must have d_ino/ed_ino
 *                and d_name/ed_name set
 *   uiop       - caller-supplied uio pointer
 *   next       - the offset of the next entry
 */
static int
gfs_readdir_emit_int(gfs_readdir_state_t *st, uio_t *uiop, offset_t next)
{
        int reclen;
        dirent64_t *dp;
        edirent_t *edp;

        if (st->grd_flags & V_RDDIR_ENTFLAGS) {
                edp = st->grd_dirent;
                reclen = EDIRENT_RECLEN(strlen(edp->ed_name));
        } else {
                dp = st->grd_dirent;
                reclen = DIRENT64_RECLEN(strlen(dp->d_name));
        }

        if (reclen > uiop->uio_resid) {
                /*
                 * Error if no entries were returned yet
                 */
                if (uiop->uio_resid == st->grd_oresid)
                        return (EINVAL);
                return (-1);
        }

        if (st->grd_flags & V_RDDIR_ENTFLAGS) {
                edp->ed_off = next;
                edp->ed_reclen = (ushort_t)reclen;
        } else {
                dp->d_off = next;
                dp->d_reclen = (ushort_t)reclen;
        }

        if (uiomove((caddr_t)st->grd_dirent, reclen, UIO_READ, uiop))
                return (EFAULT);

        uiop->uio_loffset = next;

        return (0);
}

/*
 * gfs_readdir_emit: emit a directory entry
 *   voff       - the virtual offset (obtained from gfs_readdir_pred)
 *   ino        - the entry's inode
 *   name       - the entry's name
 *   eflags     - value for ed_eflags (if processing edirent_t)
 *
 * Returns a 0 on success, a non-zero errno on failure, or -1 if the
 * readdir loop should terminate.  A non-zero result (either errno or
 * -1) from this function is typically passed directly to
 * gfs_readdir_fini().
 */
int
gfs_readdir_emit(gfs_readdir_state_t *st, uio_t *uiop, offset_t voff,
    ino64_t ino, const char *name, int eflags)
{
        offset_t off = (voff + 2) * st->grd_ureclen;

        if (st->grd_flags & V_RDDIR_ENTFLAGS) {
                edirent_t *edp = st->grd_dirent;

                edp->ed_ino = ino;
                (void) strncpy(edp->ed_name, name, st->grd_namlen);
                edp->ed_eflags = eflags;
        } else {
                dirent64_t *dp = st->grd_dirent;

                dp->d_ino = ino;
                (void) strncpy(dp->d_name, name, st->grd_namlen);
        }

        /*
         * Inter-entry offsets are invalid, so we assume a record size of
         * grd_ureclen and explicitly set the offset appropriately.
         */
        return (gfs_readdir_emit_int(st, uiop, off + st->grd_ureclen));
}

/*
 * gfs_readdir_emitn: like gfs_readdir_emit(), but takes an integer
 * instead of a string for the entry's name.
 */
int
gfs_readdir_emitn(gfs_readdir_state_t *st, uio_t *uiop, offset_t voff,
    ino64_t ino, unsigned long num)
{
        char buf[40];

        numtos(num, buf);
        return (gfs_readdir_emit(st, uiop, voff, ino, buf, 0));
}

/*
 * gfs_readdir_pred: readdir loop predicate
 *   voffp - a pointer in which the next virtual offset should be stored
 *
 * Returns a 0 on success, a non-zero errno on failure, or -1 if the
 * readdir loop should terminate.  A non-zero result (either errno or
 * -1) from this function is typically passed directly to
 * gfs_readdir_fini().
 */
int
gfs_readdir_pred(gfs_readdir_state_t *st, uio_t *uiop, offset_t *voffp)
{
        offset_t off, voff;
        int error;

top:
        if (uiop->uio_resid <= 0)
                return (-1);

        off = uiop->uio_loffset / st->grd_ureclen;
        voff = off - 2;
        if (off == 0) {
                if ((error = gfs_readdir_emit(st, uiop, voff, st->grd_self,
                    ".", 0)) == 0)
                        goto top;
        } else if (off == 1) {
                if ((error = gfs_readdir_emit(st, uiop, voff, st->grd_parent,
                    "..", 0)) == 0)
                        goto top;
        } else {
                *voffp = voff;
                return (0);
        }

        return (error);
}

/*
 * gfs_readdir_fini: generic readdir cleanup
 *   error      - if positive, an error to return
 *   eofp       - the eofp passed to readdir
 *   eof        - the eof value
 *
 * Returns a 0 on success, a non-zero errno on failure.  This result
 * should be returned from readdir.
 */
int
gfs_readdir_fini(gfs_readdir_state_t *st, int error, int *eofp, int eof)
{
        size_t dirent_size;

        if (st->grd_flags & V_RDDIR_ENTFLAGS)
                dirent_size = EDIRENT_RECLEN(st->grd_namlen);
        else
                dirent_size = DIRENT64_RECLEN(st->grd_namlen);
        kmem_free(st->grd_dirent, dirent_size);
        if (error > 0)
                return (error);
        if (eofp)
                *eofp = eof;
        return (0);
}

/*
 * gfs_lookup_dot
 *
 * Performs a basic check for "." and ".." directory entries.
 */
int
gfs_lookup_dot(vnode_t **vpp, vnode_t *dvp, vnode_t *pvp, const char *nm)
{
        if (*nm == '\0' || strcmp(nm, ".") == 0) {
                VN_HOLD(dvp);
                *vpp = dvp;
                return (0);
        } else if (strcmp(nm, "..") == 0) {
                if (pvp == NULL) {
                        ASSERT(dvp->v_flag & VROOT);
                        VN_HOLD(dvp);
                        *vpp = dvp;
                } else {
                        VN_HOLD(pvp);
                        *vpp = pvp;
                }
                return (0);
        }

        return (-1);
}

/*
 * gfs_file_create(): create a new GFS file
 *
 *   size       - size of private data structure (v_data)
 *   pvp        - parent vnode (GFS directory)
 *   ops        - vnode operations vector
 *
 * In order to use this interface, the parent vnode must have been created by
 * gfs_dir_create(), and the private data stored in v_data must have a
 * 'gfs_file_t' as its first field.
 *
 * Given these constraints, this routine will automatically:
 *
 *      - Allocate v_data for the vnode
 *      - Initialize necessary fields in the vnode
 *      - Hold the parent
 */
struct vnode *
gfs_file_create(size_t size, struct vnode *pvp, const struct vnodeops *ops)
{
        gfs_file_t *fp;
        struct vnode *vp;

        /*
         * Allocate vnode and internal data structure
         */
        fp = kmem_zalloc(size, KM_SLEEP);
        vp = vn_alloc(KM_SLEEP);

        /*
         * Set up various pointers
         */
        fp->gfs_vnode = vp;
        fp->gfs_parent = pvp;
        vp->v_data = fp;
        fp->gfs_size = size;
        fp->gfs_type = GFS_FILE;

        /*
         * Initialize vnode and hold parent.
         */
        vn_setops(vp, ops);
        if (pvp) {
                VN_SET_VFS_TYPE_DEV(vp, pvp->v_vfsp, VREG, 0);
                VN_HOLD(pvp);
        }

        return (vp);
}

/*
 * gfs_dir_create: creates a new directory in the parent
 *
 *   size       - size of private data structure (v_data)
 *   pvp        - parent vnode (GFS directory)
 *   ops        - vnode operations vector
 *   entries    - NULL-terminated list of static entries (if any)
 *   maxlen     - maximum length of a directory entry
 *   readdir_cb - readdir callback (see gfs_dir_readdir)
 *   inode_cb   - inode callback (see gfs_dir_readdir)
 *   lookup_cb  - lookup callback (see gfs_dir_lookup)
 *
 * In order to use this function, the first member of the private vnode
 * structure (v_data) must be a gfs_dir_t.  For each directory, there are
 * static entries, defined when the structure is initialized, and dynamic
 * entries, retrieved through callbacks.
 *
 * If a directory has static entries, then it must supply a inode callback,
 * which will compute the inode number based on the parent and the index.
 * For a directory with dynamic entries, the caller must supply a readdir
 * callback and a lookup callback.  If a static lookup fails, we fall back to
 * the supplied lookup callback, if any.
 *
 * This function also performs the same initialization as gfs_file_create().
 */
struct vnode *
gfs_dir_create(size_t struct_size, struct vnode *pvp,
    const struct vnodeops *ops,
    gfs_dirent_t *entries, gfs_inode_cb inode_cb, int maxlen,
    gfs_readdir_cb readdir_cb, gfs_lookup_cb lookup_cb)
{
        vnode_t *vp;
        gfs_dir_t *dp;
        gfs_dirent_t *de;

        vp = gfs_file_create(struct_size, pvp, ops);
        vp->v_type = VDIR;

        dp = vp->v_data;
        dp->gfsd_file.gfs_type = GFS_DIR;
        dp->gfsd_maxlen = maxlen;

        if (entries != NULL) {
                for (de = entries; de->gfse_name != NULL; de++)
                        dp->gfsd_nstatic++;

                dp->gfsd_static = kmem_alloc(
                    dp->gfsd_nstatic * sizeof (gfs_dirent_t), KM_SLEEP);
                bcopy(entries, dp->gfsd_static,
                    dp->gfsd_nstatic * sizeof (gfs_dirent_t));
        }

        dp->gfsd_readdir = readdir_cb;
        dp->gfsd_lookup = lookup_cb;
        dp->gfsd_inode = inode_cb;

        mutex_init(&dp->gfsd_lock, NULL, MUTEX_DEFAULT, NULL);

        return (vp);
}

/*
 * gfs_root_create(): create a root vnode for a GFS filesystem
 *
 * Similar to gfs_dir_create(), this creates a root vnode for a filesystem.  The
 * only difference is that it takes a vfs_t instead of a vnode_t as its parent.
 */
struct vnode *
gfs_root_create(size_t size, struct vfs *vfsp,
    const struct vnodeops *ops, ino64_t ino,
    gfs_dirent_t *entries, gfs_inode_cb inode_cb, int maxlen,
    gfs_readdir_cb readdir_cb, gfs_lookup_cb lookup_cb)
{
        struct vnode *vp = gfs_dir_create(size, NULL, ops, entries, inode_cb,
            maxlen, readdir_cb, lookup_cb);

        /* Manually set the inode */
        ((gfs_file_t *)vp->v_data)->gfs_ino = ino;

        VFS_HOLD(vfsp);
        VN_SET_VFS_TYPE_DEV(vp, vfsp, VDIR, 0);
        vp->v_flag |= VROOT | VNOCACHE | VNOMAP | VNOSWAP | VNOMOUNT;

        return (vp);
}

/*
 * gfs_root_create_file(): create a root vnode for a GFS file as a filesystem
 *
 * Similar to gfs_root_create(), this creates a root vnode for a file to
 * be the pseudo-filesystem.
 */
struct vnode *
gfs_root_create_file(size_t size, struct vfs *vfsp,
    const struct vnodeops *ops, ino64_t ino)
{
        struct vnode *vp = gfs_file_create(size, NULL, ops);

        ((gfs_file_t *)vp->v_data)->gfs_ino = ino;

        VFS_HOLD(vfsp);
        VN_SET_VFS_TYPE_DEV(vp, vfsp, VREG, 0);
        vp->v_flag |= VROOT | VNOCACHE | VNOMAP | VNOSWAP | VNOMOUNT;

        return (vp);
}

/*
 * gfs_file_inactive()
 *
 * Called from the fop_inactive() routine.  If necessary, this routine will
 * remove the given vnode from the parent directory and clean up any references
 * in the VFS layer.
 *
 * If the vnode was not removed (due to a race with vget), then NULL is
 * returned.  Otherwise, a pointer to the private data is returned.
 */
void *
gfs_file_inactive(vnode_t *vp)
{
        int i;
        gfs_dirent_t *ge = NULL;
        gfs_file_t *fp = vp->v_data;
        gfs_dir_t *dp = NULL;
        void *data;

        if (fp->gfs_parent == NULL || (vp->v_flag & V_XATTRDIR))
                goto found;

        dp = fp->gfs_parent->v_data;

        /*
         * First, see if this vnode is cached in the parent.
         */
        gfs_dir_lock(dp);

        /*
         * Find it in the set of static entries.
         */
        for (i = 0; i < dp->gfsd_nstatic; i++)  {
                ge = &dp->gfsd_static[i];

                if (ge->gfse_vnode == vp)
                        goto found;
        }

        /*
         * If 'ge' is NULL, then it is a dynamic entry.
         */
        ge = NULL;

found:
        if (vp->v_flag & V_XATTRDIR) {
                mutex_enter(&fp->gfs_parent->v_lock);
        }
        mutex_enter(&vp->v_lock);
        if (vp->v_count == 1) {
                /*
                 * Really remove this vnode
                 */
                data = vp->v_data;
                if (ge != NULL) {
                        /*
                         * If this was a statically cached entry, simply set the
                         * cached vnode to NULL.
                         */
                        ge->gfse_vnode = NULL;
                }
                if (vp->v_flag & V_XATTRDIR) {
                        fp->gfs_parent->v_xattrdir = NULL;
                        mutex_exit(&fp->gfs_parent->v_lock);
                }
                mutex_exit(&vp->v_lock);

                /*
                 * Free vnode and release parent
                 */
                if (fp->gfs_parent) {
                        if (dp) {
                                gfs_dir_unlock(dp);
                        }
                        VN_RELE(fp->gfs_parent);
                } else {
                        ASSERT(vp->v_vfsp != NULL);
                        VFS_RELE(vp->v_vfsp);
                }
                vn_free(vp);
        } else {
                VN_RELE_LOCKED(vp);
                data = NULL;
                mutex_exit(&vp->v_lock);
                if (vp->v_flag & V_XATTRDIR) {
                        mutex_exit(&fp->gfs_parent->v_lock);
                }
                if (dp)
                        gfs_dir_unlock(dp);
        }

        return (data);
}

/*
 * gfs_dir_inactive()
 *
 * Same as above, but for directories.
 */
void *
gfs_dir_inactive(vnode_t *vp)
{
        gfs_dir_t *dp;

        ASSERT(vp->v_type == VDIR);

        if ((dp = gfs_file_inactive(vp)) != NULL) {
                mutex_destroy(&dp->gfsd_lock);
                if (dp->gfsd_nstatic)
                        kmem_free(dp->gfsd_static,
                            dp->gfsd_nstatic * sizeof (gfs_dirent_t));
        }

        return (dp);
}

/*
 * gfs_dir_lookup_dynamic()
 *
 * This routine looks up the provided name amongst the dynamic entries
 * in the gfs directory and returns the corresponding vnode, if found.
 *
 * The gfs directory is expected to be locked by the caller prior to
 * calling this function.  The directory will be unlocked during the
 * execution of this function, but will be locked upon return from the
 * function.  This function returns 0 on success, non-zero on error.
 *
 * The dynamic lookups are performed by invoking the lookup
 * callback, which is passed to this function as the first argument.
 * The arguments to the callback are:
 *
 * int gfs_lookup_cb(vnode_t *pvp, const char *nm, vnode_t **vpp, cred_t *cr,
 *     int flags, int *deflgs, pathname_t *rpnp);
 *
 *      pvp     - parent vnode
 *      nm      - name of entry
 *      vpp     - pointer to resulting vnode
 *      cr      - pointer to cred
 *      flags   - flags value from lookup request
 *              ignored here; currently only used to request
 *              insensitive lookups
 *      direntflgs - output parameter, directory entry flags
 *              ignored here; currently only used to indicate a lookup
 *              has more than one possible match when case is not considered
 *      realpnp - output parameter, real pathname
 *              ignored here; when lookup was performed case-insensitively,
 *              this field contains the "real" name of the file.
 *
 *      Returns 0 on success, non-zero on error.
 */
static int
gfs_dir_lookup_dynamic(gfs_lookup_cb callback, gfs_dir_t *dp,
    const char *nm, vnode_t *dvp, vnode_t **vpp, cred_t *cr, int flags,
    int *direntflags, pathname_t *realpnp)
{
        gfs_file_t *fp;
        ino64_t ino;
        int ret;

        ASSERT(GFS_DIR_LOCKED(dp));

        /*
         * Drop the directory lock, as the lookup routine
         * will need to allocate memory, or otherwise deadlock on this
         * directory.
         */
        gfs_dir_unlock(dp);
        ret = callback(dvp, nm, vpp, &ino, cr, flags, direntflags, realpnp);
        gfs_dir_lock(dp);

        /*
         * The callback for extended attributes returns a vnode
         * with v_data from an underlying fs.
         */
        if (ret == 0 && !IS_XATTRDIR(dvp)) {
                fp = (gfs_file_t *)((*vpp)->v_data);
                fp->gfs_index = -1;
                fp->gfs_ino = ino;
        }

        return (ret);
}

/*
 * gfs_dir_lookup_static()
 *
 * This routine looks up the provided name amongst the static entries
 * in the gfs directory and returns the corresponding vnode, if found.
 * The first argument to the function is a pointer to the comparison
 * function this function should use to decide if names are a match.
 *
 * If a match is found, and GFS_CACHE_VNODE is set and the vnode
 * exists, we simply return the existing vnode.  Otherwise, we call
 * the static entry's callback routine, caching the result if
 * necessary.  If the idx pointer argument is non-NULL, we use it to
 * return the index of the matching static entry.
 *
 * The gfs directory is expected to be locked by the caller prior to calling
 * this function.  The directory may be unlocked during the execution of
 * this function, but will be locked upon return from the function.
 *
 * This function returns 0 if a match is found, ENOENT if not.
 */
static int
gfs_dir_lookup_static(int (*compare)(const char *, const char *),
    gfs_dir_t *dp, const char *nm, vnode_t *dvp, int *idx,
    vnode_t **vpp, pathname_t *rpnp)
{
        gfs_dirent_t *ge;
        vnode_t *vp = NULL;
        int i;

        ASSERT(GFS_DIR_LOCKED(dp));

        /*
         * Search static entries.
         */
        for (i = 0; i < dp->gfsd_nstatic; i++) {
                ge = &dp->gfsd_static[i];

                if (compare(ge->gfse_name, nm) == 0) {
                        if (rpnp)
                                (void) strlcpy(rpnp->pn_buf, ge->gfse_name,
                                    rpnp->pn_bufsize);

                        if (ge->gfse_vnode) {
                                ASSERT(ge->gfse_flags & GFS_CACHE_VNODE);
                                vp = ge->gfse_vnode;
                                VN_HOLD(vp);
                                break;
                        }

                        /*
                         * We drop the directory lock, as the constructor will
                         * need to do KM_SLEEP allocations.  If we return from
                         * the constructor only to find that a parallel
                         * operation has completed, and GFS_CACHE_VNODE is set
                         * for this entry, we discard the result in favor of
                         * the cached vnode.
                         */
                        gfs_dir_unlock(dp);
                        vp = ge->gfse_ctor(dvp);
                        gfs_dir_lock(dp);

                        ((gfs_file_t *)vp->v_data)->gfs_index = i;

                        /* Set the inode according to the callback. */
                        ((gfs_file_t *)vp->v_data)->gfs_ino =
                            dp->gfsd_inode(dvp, i);

                        if (ge->gfse_flags & GFS_CACHE_VNODE) {
                                if (ge->gfse_vnode == NULL) {
                                        ge->gfse_vnode = vp;
                                } else {
                                        /*
                                         * A parallel constructor beat us to it;
                                         * return existing vnode.  We have to be
                                         * careful because we can't release the
                                         * current vnode while holding the
                                         * directory lock; its inactive routine
                                         * will try to lock this directory.
                                         */
                                        vnode_t *oldvp = vp;
                                        vp = ge->gfse_vnode;
                                        VN_HOLD(vp);

                                        gfs_dir_unlock(dp);
                                        VN_RELE(oldvp);
                                        gfs_dir_lock(dp);
                                }
                        }
                        break;
                }
        }

        if (vp == NULL)
                return (ENOENT);
        else if (idx)
                *idx = i;
        *vpp = vp;
        return (0);
}

/*
 * gfs_dir_lookup()
 *
 * Looks up the given name in the directory and returns the corresponding
 * vnode, if found.
 *
 * First, we search statically defined entries, if any, with a call to
 * gfs_dir_lookup_static().  If no static entry is found, and we have
 * a callback function we try a dynamic lookup via gfs_dir_lookup_dynamic().
 *
 * This function returns 0 on success, non-zero on error.
 */
int
gfs_dir_lookup(vnode_t *dvp, const char *nm, vnode_t **vpp, cred_t *cr,
    int flags, int *direntflags, pathname_t *realpnp)
{
        gfs_dir_t *dp = dvp->v_data;
        boolean_t casecheck;
        vnode_t *dynvp = NULL;
        vnode_t *vp = NULL;
        int (*compare)(const char *, const char *);
        int error, idx;

        ASSERT(dvp->v_type == VDIR);

        if (gfs_lookup_dot(vpp, dvp, dp->gfsd_file.gfs_parent, nm) == 0)
                return (0);

        casecheck = (flags & FIGNORECASE) != 0 && direntflags != NULL;
        if (vfs_has_feature(dvp->v_vfsp, VFSFT_NOCASESENSITIVE) ||
            (flags & FIGNORECASE))
                compare = strcasecmp;
        else
                compare = strcmp;

        gfs_dir_lock(dp);

        error = gfs_dir_lookup_static(compare, dp, nm, dvp, &idx, &vp, realpnp);

        if (vp && casecheck) {
                gfs_dirent_t *ge;
                int i;

                for (i = idx + 1; i < dp->gfsd_nstatic; i++) {
                        ge = &dp->gfsd_static[i];

                        if (strcasecmp(ge->gfse_name, nm) == 0) {
                                *direntflags |= ED_CASE_CONFLICT;
                                goto out;
                        }
                }
        }

        if ((error || casecheck) && dp->gfsd_lookup)
                error = gfs_dir_lookup_dynamic(dp->gfsd_lookup, dp, nm, dvp,
                    &dynvp, cr, flags, direntflags, vp ? NULL : realpnp);

        if (vp && dynvp) {
                /* static and dynamic entries are case-insensitive conflict */
                ASSERT(casecheck);
                *direntflags |= ED_CASE_CONFLICT;
                VN_RELE(dynvp);
        } else if (vp == NULL) {
                vp = dynvp;
        } else if (error == ENOENT) {
                error = 0;
        } else if (error) {
                VN_RELE(vp);
                vp = NULL;
        }

out:
        gfs_dir_unlock(dp);

        *vpp = vp;
        return (error);
}

/*
 * gfs_dir_readdir: does a readdir() on the given directory
 *
 *    dvp       - directory vnode
 *    uiop      - uio structure
 *    eofp      - eof pointer
 *    data      - arbitrary data passed to readdir callback
 *
 * This routine does all the readdir() dirty work.  Even so, the caller must
 * supply two callbacks in order to get full compatibility.
 *
 * If the directory contains static entries, an inode callback must be
 * specified.  This avoids having to create every vnode and call fop_getattr()
 * when reading the directory.  This function has the following arguments:
 *
 *      ino_t gfs_inode_cb(vnode_t *vp, int index);
 *
 *      vp      - vnode for the directory
 *      index   - index in original gfs_dirent_t array
 *
 *      Returns the inode number for the given entry.
 *
 * For directories with dynamic entries, a readdir callback must be provided.
 * This is significantly more complex, thanks to the particulars of
 * fop_readdir().
 *
 *      int gfs_readdir_cb(vnode_t *vp, void *dp, int *eofp,
 *          offset_t *off, offset_t *nextoff, void *data, int flags)
 *
 *      vp      - directory vnode
 *      dp      - directory entry, sized according to maxlen given to
 *                gfs_dir_create().  callback must fill in d_name and
 *                d_ino (if a dirent64_t), or ed_name, ed_ino, and ed_eflags
 *                (if an edirent_t). edirent_t is used if V_RDDIR_ENTFLAGS
 *                is set in 'flags'.
 *      eofp    - callback must set to 1 when EOF has been reached
 *      off     - on entry, the last offset read from the directory.  Callback
 *                must set to the offset of the current entry, typically left
 *                untouched.
 *      nextoff - callback must set to offset of next entry.  Typically
 *                (off + 1)
 *      data    - caller-supplied data
 *      flags   - fop_readdir flags
 *
 *      Return 0 on success, or error on failure.
 */
int
gfs_dir_readdir(vnode_t *dvp, uio_t *uiop, int *eofp, void *data, cred_t *cr,
    caller_context_t *ct, int flags)
{
        gfs_readdir_state_t gstate;
        int error, eof = 0;
        ino64_t ino, pino;
        offset_t off, next;
        gfs_dir_t *dp = dvp->v_data;

        error = gfs_get_parent_ino(dvp, cr, ct, &pino, &ino);
        if (error)
                return (error);

        if ((error = gfs_readdir_init(&gstate, dp->gfsd_maxlen, 1, uiop,
            pino, ino, flags)) != 0)
                return (error);

        while ((error = gfs_readdir_pred(&gstate, uiop, &off)) == 0 &&
            !eof) {

                if (off >= 0 && off < dp->gfsd_nstatic) {
                        ino = dp->gfsd_inode(dvp, off);

                        if ((error = gfs_readdir_emit(&gstate, uiop,
                            off, ino, dp->gfsd_static[off].gfse_name, 0))
                            != 0)
                                break;

                } else if (dp->gfsd_readdir) {
                        off -= dp->gfsd_nstatic;

                        if ((error = dp->gfsd_readdir(dvp,
                            gstate.grd_dirent, &eof, &off, &next,
                            data, flags)) != 0 || eof)
                                break;

                        off += dp->gfsd_nstatic + 2;
                        next += dp->gfsd_nstatic + 2;

                        if ((error = gfs_readdir_emit_int(&gstate, uiop,
                            next)) != 0)
                                break;
                } else {
                        /*
                         * Offset is beyond the end of the static entries, and
                         * we have no dynamic entries.  Set EOF.
                         */
                        eof = 1;
                }
        }

        return (gfs_readdir_fini(&gstate, error, eofp, eof));
}


/*
 * gfs_vop_lookup: fop_lookup() entry point
 *
 * For use directly in vnode ops table.  Given a GFS directory, calls
 * gfs_dir_lookup() as necessary.
 */
/* ARGSUSED */
int
gfs_vop_lookup(vnode_t *dvp, char *nm, vnode_t **vpp, pathname_t *pnp,
    int flags, vnode_t *rdir, cred_t *cr, caller_context_t *ct,
    int *direntflags, pathname_t *realpnp)
{
        return (gfs_dir_lookup(dvp, nm, vpp, cr, flags, direntflags, realpnp));
}

/*
 * gfs_vop_readdir: fop_readdir() entry point
 *
 * For use directly in vnode ops table.  Given a GFS directory, calls
 * gfs_dir_readdir() as necessary.
 */
/* ARGSUSED */
int
gfs_vop_readdir(vnode_t *vp, uio_t *uiop, cred_t *cr, int *eofp,
    caller_context_t *ct, int flags)
{
        return (gfs_dir_readdir(vp, uiop, eofp, NULL, cr, ct, flags));
}


/*
 * gfs_vop_map: fop_map() entry point
 *
 * Convenient routine for handling pseudo-files that wish to allow mmap() calls.
 * This function only works for readonly files, and uses the read function for
 * the vnode to fill in the data.  The mapped data is immediately faulted in and
 * filled with the necessary data during this call; there are no getpage() or
 * putpage() routines.
 */
/* ARGSUSED */
int
gfs_vop_map(vnode_t *vp, offset_t off, struct as *as, caddr_t *addrp,
    size_t len, uchar_t prot, uchar_t maxprot, uint_t flags, cred_t *cred,
    caller_context_t *ct)
{
        int rv;
        ssize_t resid = len;

        /*
         * Check for bad parameters
         */
#ifdef _ILP32
        if (len > MAXOFF_T)
                return (ENOMEM);
#endif
        if (vp->v_flag & VNOMAP)
                return (ENOTSUP);
        if (off > MAXOFF_T)
                return (EFBIG);
        if ((long)off < 0 || (long)(off + len) < 0)
                return (EINVAL);
        if (vp->v_type != VREG)
                return (ENODEV);
        if ((prot & (PROT_EXEC | PROT_WRITE)) != 0)
                return (EACCES);

        /*
         * Find appropriate address if needed, otherwise clear address range.
         */
        as_rangelock(as);
        rv = choose_addr(as, addrp, len, off, ADDR_VACALIGN, flags);
        if (rv != 0) {
                as_rangeunlock(as);
                return (rv);
        }

        /*
         * Create mapping
         */
        rv = as_map(as, *addrp, len, segvn_create, zfod_argsp);
        as_rangeunlock(as);
        if (rv != 0)
                return (rv);

        /*
         * Fill with data from read()
         */
        rv = vn_rdwr(UIO_READ, vp, *addrp, len, off, UIO_USERSPACE,
            0, 0, cred, &resid);

        if (rv == 0 && resid != 0)
                rv = ENXIO;

        if (rv != 0) {
                as_rangelock(as);
                (void) as_unmap(as, *addrp, len);
                as_rangeunlock(as);
        }

        return (rv);
}

/*
 * gfs_vop_inactive: fop_inactive() entry point
 *
 * Given a vnode that is a GFS file or directory, call gfs_file_inactive() or
 * gfs_dir_inactive() as necessary, and kmem_free()s associated private data.
 */
/* ARGSUSED */
void
gfs_vop_inactive(vnode_t *vp, cred_t *cr, caller_context_t *ct)
{
        gfs_file_t *fp = vp->v_data;
        void *data;

        if (fp->gfs_type == GFS_DIR)
                data = gfs_dir_inactive(vp);
        else
                data = gfs_file_inactive(vp);

        if (data != NULL)
                kmem_free(data, fp->gfs_size);
}